Accuracy and calibration of integrated radiation output indicators in diagnostic radiology: A report of the AAPM Imaging Physics Committee Task Group 190

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lin, Pei-Jan P., E-mail: Pei-Jan.Lin@vcuhealth.org; Schueler, Beth A.; Balter, Stephen

2015-12-15

Due to the proliferation of disciplines employing fluoroscopy as their primary imaging tool and the prolonged extensive use of fluoroscopy in interventional and cardiovascular angiography procedures, “dose-area-product” (DAP) meters were installed to monitor and record the radiation dose delivered to patients. In some cases, the radiation dose or the output value is calculated, rather than measured, using the pertinent radiological parameters and geometrical information. The AAPM Task Group 190 (TG-190) was established to evaluate the accuracy of the DAP meter in 2008. Since then, the term “DAP-meter” has been revised to air kerma-area product (KAP) meter. The charge of TGmore » 190 (Accuracy and Calibration of Integrated Radiation Output Indicators in Diagnostic Radiology) has also been realigned to investigate the “Accuracy and Calibration of Integrated Radiation Output Indicators” which is reflected in the title of the task group, to include situations where the KAP may be acquired with or without the presence of a physical “meter.” To accomplish this goal, validation test protocols were developed to compare the displayed radiation output value to an external measurement. These test protocols were applied to a number of clinical systems to collect information on the accuracy of dose display values in the field.« less

Development and testing of a database of NIH research funding of AAPM members: A report from the AAPM Working Group for the Development of a Research Database (WGDRD).

PubMed

Whelan, Brendan; Moros, Eduardo G; Fahrig, Rebecca; Deye, James; Yi, Thomas; Woodward, Michael; Keall, Paul; Siewerdsen, Jeff H

2017-04-01

To produce and maintain a database of National Institutes of Health (NIH) funding of the American Association of Physicists in Medicine (AAPM) members, to perform a top-level analysis of these data, and to make these data (hereafter referred to as the AAPM research database) available for the use of the AAPM and its members. NIH-funded research dating back to 1985 is available for public download through the NIH exporter website, and AAPM membership information dating back to 2002 was supplied by the AAPM. To link these two sources of data, a data mining algorithm was developed in Matlab. The false-positive rate was manually estimated based on a random sample of 100 records, and the false-negative rate was assessed by comparing against 99 member-supplied PI_ID numbers. The AAPM research database was queried to produce an analysis of trends and demographics in research funding dating from 2002 to 2015. A total of 566 PI_ID numbers were matched to AAPM members. False-positive and -negative rates were respectively 4% (95% CI: 1-10%, N = 100) and 10% (95% CI: 5-18%, N = 99). Based on analysis of the AAPM research database, in 2015 the NIH awarded $USD 110M to members of the AAPM. The four NIH institutes which historically awarded the most funding to AAPM members were the National Cancer Institute, National Institute of Biomedical Imaging and Bioengineering, National Heart Lung and Blood Institute, and National Institute of Neurological Disorders and Stroke. In 2015, over 85% of the total NIH research funding awarded to AAPM members was via these institutes, representing 1.1% of their combined budget. In the same year, 2.0% of AAPM members received NIH funding for a total of $116M, which is lower than the historic mean of $120M (in 2015 USD). A database of NIH-funded research awarded to AAPM members has been developed and tested using a data mining approach, and a top-level analysis of funding trends has been performed. Current funding of AAPM members is lower than the historic mean. The database will be maintained by members of the Working group for the development of a research database (WGDRD) on an annual basis, and is available to the AAPM, its committees, working groups, and members for download through the AAPM electronic content website. A wide range of questions regarding financial and demographic funding trends can be addressed by these data. This report has been approved for publication by the AAPM Science Council. © 2017 American Association of Physicists in Medicine.

Essentials and guidelines for clinical medical physics residency training programs: executive summary of AAPM Report Number 249.

PubMed

Prisciandaro, Joann I; Willis, Charles E; Burmeister, Jay W; Clarke, Geoffrey D; Das, Rupak K; Esthappan, Jacqueline; Gerbi, Bruce J; Harkness, Beth A; Patton, James A; Peck, Donald J; Pizzutiello, Robert J; Sandison, George A; White, Sharon L; Wichman, Brian D; Ibbott, Geoffrey S; Both, Stefan

2014-05-08

There is a clear need for established standards for medical physics residency training. The complexity of techniques in imaging, nuclear medicine, and radiation oncology continues to increase with each passing year. It is therefore imperative that training requirements and competencies are routinely reviewed and updated to reflect the changing environment in hospitals and clinics across the country. In 2010, the AAPM Work Group on Periodic Review of Medical Physics Residency Training was formed and charged with updating AAPM Report Number 90. This work group includes AAPM members with extensive experience in clinical, professional, and educational aspects of medical physics. The resulting report, AAPM Report Number 249, concentrates on the clinical and professional knowledge needed to function independently as a practicing medical physicist in the areas of radiation oncology, imaging, and nuclear medicine, and constitutes a revision to AAPM Report Number 90. This manuscript presents an executive summary of AAPM Report Number 249.

Essentials and guidelines for clinical medical physics residency training programs: executive summary of AAPM Report Number 249

PubMed Central

Willis, Charles E.; Burmeister, Jay W.; Clarke, Geoffrey D.; Das, Rupak K.; Esthappan, Jacqueline; Gerbi, Bruce J.; Harkness, Beth A.; Patton, James A.; Peck, Donald J.; Pizzutiello, Robert J.; Sandison, George A.; White, Sharon L.; Wichman, Brian D.; Ibbott, Geoffrey S.; Both, Stefan

2014-01-01

There is a clear need for established standards for medical physics residency training. The complexity of techniques in imaging, nuclear medicine, and radiation oncology continues to increase with each passing year. It is therefore imperative that training requirements and competencies are routinely reviewed and updated to reflect the changing environment in hospitals and clinics across the country. In 2010, the AAPM Work Group on Periodic Review of Medical Physics Residency Training was formed and charged with updating AAPM Report Number 90. This work group includes AAPM members with extensive experience in clinical, professional, and educational aspects of medical physics. The resulting report, AAPM Report Number 249, concentrates on the clinical and professional knowledge needed to function independently as a practicing medical physicist in the areas of radiation oncology, imaging, and nuclear medicine, and constitutes a revision to AAPM Report Number 90. This manuscript presents an executive summary of AAPM Report Number 249. PACS number: 87.10.‐e PMID:24892354

Dose comparison between CTDI and the AAPM Report No. 111 methodology in adult, adolescent, and child head phantom

NASA Astrophysics Data System (ADS)

Li, Celina L.; Thakur, Yogesh; Ford, Nancy L.

2017-03-01

The standard computed tomography dose index (CTDI) metric tends to underestimate scatter radiation in cone beam computed tomography (CBCT) acquisition; therefore, the American Association of Physicists in Medicine (AAPM) Task Group 111 proposed a new dosimetry methodology to measure equilibrium dose at the center of a phantom (z = 0) using a 2-cm thimble ionization chamber. In this study, we implement the CTDI and the AAPM method with a thimble chamber on adult, adolescent, and child head phantoms using the Toshiba Aquilion One CBCT and compare the results to the CTDI measured with a 10-cm pencil chamber. Following the AAPM protocol, the normalized (100 mAs) equilibrium doses (Deq) computed using dose measurements taken in the central hole of the phantom (Deq,c), the peripheral hole of the phantom, (Deq,p), and by the CTDIw equation (Deq,w) are 20.13 +/- 0.19, 21.53 +/- 0.48, and 20.93 +/- 0.40 mGy for adult; 21.55 +/- 0.40, 21.14 +/- 0.43, and 21.08 +/- 0.45 mGy for adolescent; and 24.58 +/- 0.40, 24.92 +/- 0.85, and 24.77 +/- 0.72 mGy for child, respectively. The CTDIw, which measured 17.70, 19.86, and 22.43 mGy for adult, adolescent and child respectively, is about 10% lower than their corresponding Deq's. The extended AAPM method proposed by Deman et al., which estimates the dose profile along the rotational axis (z axis), has demonstrated consistency between theoretical and experimental results for all phantoms. With the introduction of the child and the adolescent head phantoms, we not only have emphasized the practical aspects including relative convenience of the CTDI method and accuracy of the AAPM method, but also proposed a method to approximate Deq for different sized patients.

Evaluation of dose from kV cone-beam computed tomography during radiotherapy: a comparison of methodologies

NASA Astrophysics Data System (ADS)

Buckley, J.; Wilkinson, D.; Malaroda, A.; Metcalfe, P.

2017-01-01

Three alternative methodologies to the Computed-Tomography Dose Index for the evaluation of Cone-Beam Computed Tomography dose are compared, the Cone-Beam Dose Index, IAEA Human Health Report No. 5 recommended methodology and the AAPM Task Group 111 recommended methodology. The protocols were evaluated for Pelvis and Thorax scan modes on Varian® On-Board Imager and Truebeam kV XI imaging systems. The weighted planar average dose was highest for the AAPM methodology across all scans, with the CBDI being the second highest overall. A 17.96% and 1.14% decrease from the TG-111 protocol to the IAEA and CBDI protocols for the Pelvis mode and 18.15% and 13.10% decrease for the Thorax mode were observed for the XI system. For the OBI system, the variation was 16.46% and 7.14% for Pelvis mode and 15.93% to the CBDI protocol in Thorax mode respectively.

AAPM Task Group 103 report on peer review in clinical radiation oncology physics

PubMed Central

Halvorsen, Per H.; Das, Indra J.; Fraser, Martin; Freedman, D. Jay; Rice, Robert E.; Ibbott, Geoffrey S.; Parsai, E. Ishmael; Robin, T. Tydings; Thomadsen, Bruce R.

2005-01-01

This report provides guidelines for a peer review process between two clinical radiation oncology physicists. While the Task Group's work was primarily focused on ensuring timely and productive independent reviews for physicists in solo practice, these guidelines may also be appropriate for physicists in a group setting, particularly when dispersed over multiple separate clinic locations. To ensure that such reviews enable a collegial exchange of professional ideas and productive critique of the entire clinical physics program, the reviews should not be used as an employee evaluation instrument by the employer. Such use is neither intended nor supported by this Task Group. Detailed guidelines are presented on the minimum content of such reviews, as well as a recommended format for reporting the findings of a review. In consideration of the full schedules faced by most clinical physicists, the process outlined herein was designed to be completed in one working day. PACS numbers: 87.53.Xd, 87.90.+y PMID:16421500

AAPM and GEC-ESTRO guidelines for image-guided robotic brachytherapy: report of Task Group 192.

PubMed

Podder, Tarun K; Beaulieu, Luc; Caldwell, Barrett; Cormack, Robert A; Crass, Jostin B; Dicker, Adam P; Fenster, Aaron; Fichtinger, Gabor; Meltsner, Michael A; Moerland, Marinus A; Nath, Ravinder; Rivard, Mark J; Salcudean, Tim; Song, Danny Y; Thomadsen, Bruce R; Yu, Yan

2014-10-01

In the last decade, there have been significant developments into integration of robots and automation tools with brachytherapy delivery systems. These systems aim to improve the current paradigm by executing higher precision and accuracy in seed placement, improving calculation of optimal seed locations, minimizing surgical trauma, and reducing radiation exposure to medical staff. Most of the applications of this technology have been in the implantation of seeds in patients with early-stage prostate cancer. Nevertheless, the techniques apply to any clinical site where interstitial brachytherapy is appropriate. In consideration of the rapid developments in this area, the American Association of Physicists in Medicine (AAPM) commissioned Task Group 192 to review the state-of-the-art in the field of robotic interstitial brachytherapy. This is a joint Task Group with the Groupe Européen de Curiethérapie-European Society for Radiotherapy & Oncology (GEC-ESTRO). All developed and reported robotic brachytherapy systems were reviewed. Commissioning and quality assurance procedures for the safe and consistent use of these systems are also provided. Manual seed placement techniques with a rigid template have an estimated in vivo accuracy of 3-6 mm. In addition to the placement accuracy, factors such as tissue deformation, needle deviation, and edema may result in a delivered dose distribution that differs from the preimplant or intraoperative plan. However, real-time needle tracking and seed identification for dynamic updating of dosimetry may improve the quality of seed implantation. The AAPM and GEC-ESTRO recommend that robotic systems should demonstrate a spatial accuracy of seed placement ≤1.0 mm in a phantom. This recommendation is based on the current performance of existing robotic brachytherapy systems and propagation of uncertainties. During clinical commissioning, tests should be conducted to ensure that this level of accuracy is achieved. These tests should mimic the real operating procedure as closely as possible. Additional recommendations on robotic brachytherapy systems include display of the operational state; capability of manual override; documented policies for independent check and data verification; intuitive interface displaying the implantation plan and visualization of needle positions and seed locations relative to the target anatomy; needle insertion in a sequential order; robot-clinician and robot-patient interactions robustness, reliability, and safety while delivering the correct dose at the correct site for the correct patient; avoidance of excessive force on radioactive sources; delivery confirmation of the required number or position of seeds; incorporation of a collision avoidance system; system cleaning, decontamination, and sterilization procedures. These recommendations are applicable to end users and manufacturers of robotic brachytherapy systems.

Stopping-power and mass energy-absorption coefficient ratios for Solid Water.

PubMed

Ho, A K; Paliwal, B R

1986-01-01

The AAPM Task Group 21 protocol provides tables of ratios of average restricted stopping powers and ratios of mean energy-absorption coefficients for different materials. These values were based on the work of Cunningham and Schulz. We have calculated these quantities for Solid Water (manufactured by RMI), using the same x-ray spectra and method as that used by Cunningham and Schulz. These values should be useful to people who are using Solid Water for high-energy photon calibration.

WE-E-213AB-01: Medical Physics Challenges for Implementation of New Technologies in External Beam Radiotherapy.

PubMed

Boiras, C; Bourland, J; Gonzalez, L Brualla; Bulychkin, P; Ford, E; Kazantsev, P; Krylova, T; Medina, A Lopez; Prusova, M; Romanov, D; Ferrando, J Rosello; Willoughby, T; Yan, D; Yu, C; Zvereva, A

2012-06-01

The AAPM has signed two formal Educational Exchange Agreements with the Spanish (SEFM) and the Russian (AMPR) medical physics societies. While the primary purpose of the Agreements is to provide educational opportunities for young medical physicists, the Agreements also contemplate holding joint sessions at scientific congresses. The purpose of this professional AAPM/SEFM/AMPR Joint Symposium is to explore the challenges that medical physicists in the three countries face when new external beam radiotherapy technologies are introduced in their facilities and to suggest potential solutions to limitations in testing equipment and lack of familiarity with protocols. Speakers from the three societies will present reviews of the technical aspects of IMRT, Arc EVIRT (IMAT/VMAT/Rapid Arc), SRS/SRBT, and IGRT/Adaptive radiotherapy, and will describe the status of these technologies in their countries, including the challenges found in tasks such as developing anatomical and biological dose optimization techniques and implementing QA management, risk assessment and patient safety programs. The SEFM will offer AAPM and AMPR members the possibility to participate in collaborative proposals for future research bids in UE and USA based on an ongoing Spanish project for adaptive radiotherapy using functional imaging. A targeted discussion will debate three propositions: the cost/benefit ratio of IGRT, whether IMRT requires IGRT, and the use of non-ionizing radiation technologies for realtime monitoring of prostate IGRT. For these debates, each society has designated one speaker to present and defend either "For" or "Against" the proposition, followed by discussion by all participants. The Symposium presentations and the country-tailored recommendations drawn will be made available to each society for inclusion in their websites. The WGNIMP, the AAPM Work Group charged with executing the AAPM/SEFM and AAPM/AMPR Agreements, will follow up on the commitments made by the AAPM.Di Yan's research on adaptive radiotherapy has been financially supported by: 1) NIH Research Grants, 2) Elekta Research Grants 3) Philips Research GrantConflicts of interest for Cedric X Yu: 1) Board Member of Prowess, Inc., 2) Shareholder of Xcision Medical Systems, LLC, 3) Inventor on patents licensed by Varian Medical Systems, Inc. 1. Describe fundamental aspects for four advanced radiotherapy techniques: IMRT, IGRT, SBRT, and adaptive radiotherapy. 2. Review technical and professional challenges for implementation of advanced techniques as a function of resources and capabilities available within each scientific society: AAPM, SEFM, and AMPR. 3. Discuss and plan a proposal for an international trial on IMRT/IGRT based on functional imaging. 4. Debate important implementation aspects of IMRT and IGRT according to country-specific resources. © 2012 American Association of Physicists in Medicine.

TU-EF-210-01: HIFU, Drug Delivery, and Immunotherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ferrara, K.

The use of therapeutic ultrasound to provide targeted therapy is an active research area that has a broad application scope. The invited talks in this session will address currently implemented strategies and protocols for both hyperthermia and ablation applications using therapeutic ultrasound. The role of both ultrasound and MRI in the monitoring and assessment of these therapies will be explored in both pre-clinical and clinical applications. Katherine Ferrara: High Intensity Focused Ultrasound, Drug Delivery, and Immunotherapy Rajiv Chopra: Translating Localized Doxorubicin Delivery to Pediatric Oncology using MRI-guided HIFU Elisa Konofagou: Real-time Ablation Monitoring and Lesion Quantification using Harmonic Motion Imagingmore » Keyvan Farahani: AAPM Task Groups in Interventional Ultrasound Imaging and Therapy Learning Objectives: Understand the role of ultrasound in localized drug delivery and the effects of immunotherapy when used in conjunction with ultrasound therapy. Understand potential targeted drug delivery clinical applications including pediatric oncology. Understand the technical requirements for performing targeted drug delivery. Understand how radiation-force approaches can be used to both monitor and assess high intensity focused ultrasound ablation therapy. Understand the role of AAPM task groups in ultrasound imaging and therapies. Chopra: Funding from Cancer Prevention and Research Initiative of Texas (CPRIT), Award R1308 Evelyn and M.R. Hudson Foundation; Research Support from Research Contract with Philips Healthcare; COI are Co-founder of FUS Instruments Inc Ferrara: Supported by NIH, UCDavis and California (CIRM and BHCE) Farahani: In-kind research support from Philips Healthcare.« less

TU-EF-210-03: Real-Time Ablation Monitoring and Lesion Quantification Using Harmonic Motion Imaging

DOE Office of Scientific and Technical Information (OSTI.GOV)

Konofagou, E.

2015-06-15

The use of therapeutic ultrasound to provide targeted therapy is an active research area that has a broad application scope. The invited talks in this session will address currently implemented strategies and protocols for both hyperthermia and ablation applications using therapeutic ultrasound. The role of both ultrasound and MRI in the monitoring and assessment of these therapies will be explored in both pre-clinical and clinical applications. Katherine Ferrara: High Intensity Focused Ultrasound, Drug Delivery, and Immunotherapy Rajiv Chopra: Translating Localized Doxorubicin Delivery to Pediatric Oncology using MRI-guided HIFU Elisa Konofagou: Real-time Ablation Monitoring and Lesion Quantification using Harmonic Motion Imagingmore » Keyvan Farahani: AAPM Task Groups in Interventional Ultrasound Imaging and Therapy Learning Objectives: Understand the role of ultrasound in localized drug delivery and the effects of immunotherapy when used in conjunction with ultrasound therapy. Understand potential targeted drug delivery clinical applications including pediatric oncology. Understand the technical requirements for performing targeted drug delivery. Understand how radiation-force approaches can be used to both monitor and assess high intensity focused ultrasound ablation therapy. Understand the role of AAPM task groups in ultrasound imaging and therapies. Chopra: Funding from Cancer Prevention and Research Initiative of Texas (CPRIT), Award R1308 Evelyn and M.R. Hudson Foundation; Research Support from Research Contract with Philips Healthcare; COI are Co-founder of FUS Instruments Inc Ferrara: Supported by NIH, UCDavis and California (CIRM and BHCE) Farahani: In-kind research support from Philips Healthcare.« less

TU-EF-210-00: Therapeutic Strategies and Image Guidance

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

2015-06-15

The use of therapeutic ultrasound to provide targeted therapy is an active research area that has a broad application scope. The invited talks in this session will address currently implemented strategies and protocols for both hyperthermia and ablation applications using therapeutic ultrasound. The role of both ultrasound and MRI in the monitoring and assessment of these therapies will be explored in both pre-clinical and clinical applications. Katherine Ferrara: High Intensity Focused Ultrasound, Drug Delivery, and Immunotherapy Rajiv Chopra: Translating Localized Doxorubicin Delivery to Pediatric Oncology using MRI-guided HIFU Elisa Konofagou: Real-time Ablation Monitoring and Lesion Quantification using Harmonic Motion Imagingmore » Keyvan Farahani: AAPM Task Groups in Interventional Ultrasound Imaging and Therapy Learning Objectives: Understand the role of ultrasound in localized drug delivery and the effects of immunotherapy when used in conjunction with ultrasound therapy. Understand potential targeted drug delivery clinical applications including pediatric oncology. Understand the technical requirements for performing targeted drug delivery. Understand how radiation-force approaches can be used to both monitor and assess high intensity focused ultrasound ablation therapy. Understand the role of AAPM task groups in ultrasound imaging and therapies. Chopra: Funding from Cancer Prevention and Research Initiative of Texas (CPRIT), Award R1308 Evelyn and M.R. Hudson Foundation; Research Support from Research Contract with Philips Healthcare; COI are Co-founder of FUS Instruments Inc Ferrara: Supported by NIH, UCDavis and California (CIRM and BHCE) Farahani: In-kind research support from Philips Healthcare.« less

TU-EF-210-02: MRg Hyperthermia

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chopra, R.

2015-06-15

The use of therapeutic ultrasound to provide targeted therapy is an active research area that has a broad application scope. The invited talks in this session will address currently implemented strategies and protocols for both hyperthermia and ablation applications using therapeutic ultrasound. The role of both ultrasound and MRI in the monitoring and assessment of these therapies will be explored in both pre-clinical and clinical applications. Katherine Ferrara: High Intensity Focused Ultrasound, Drug Delivery, and Immunotherapy Rajiv Chopra: Translating Localized Doxorubicin Delivery to Pediatric Oncology using MRI-guided HIFU Elisa Konofagou: Real-time Ablation Monitoring and Lesion Quantification using Harmonic Motion Imagingmore » Keyvan Farahani: AAPM Task Groups in Interventional Ultrasound Imaging and Therapy Learning Objectives: Understand the role of ultrasound in localized drug delivery and the effects of immunotherapy when used in conjunction with ultrasound therapy. Understand potential targeted drug delivery clinical applications including pediatric oncology. Understand the technical requirements for performing targeted drug delivery. Understand how radiation-force approaches can be used to both monitor and assess high intensity focused ultrasound ablation therapy. Understand the role of AAPM task groups in ultrasound imaging and therapies. Chopra: Funding from Cancer Prevention and Research Initiative of Texas (CPRIT), Award R1308 Evelyn and M.R. Hudson Foundation; Research Support from Research Contract with Philips Healthcare; COI are Co-founder of FUS Instruments Inc Ferrara: Supported by NIH, UCDavis and California (CIRM and BHCE) Farahani: In-kind research support from Philips Healthcare.« less

Monitor unit calculations for external photon and electron beams: Report of the AAPM Therapy Physics Committee Task Group No. 71

PubMed Central

Gibbons, John P.; Antolak, John A.; Followill, David S.; Huq, M. Saiful; Klein, Eric E.; Lam, Kwok L.; Palta, Jatinder R.; Roback, Donald M.; Reid, Mark; Khan, Faiz M.

2014-01-01

A protocol is presented for the calculation of monitor units (MU) for photon and electron beams, delivered with and without beam modifiers, for constant source-surface distance (SSD) and source-axis distance (SAD) setups. This protocol was written by Task Group 71 of the Therapy Physics Committee of the American Association of Physicists in Medicine (AAPM) and has been formally approved by the AAPM for clinical use. The protocol defines the nomenclature for the dosimetric quantities used in these calculations, along with instructions for their determination and measurement. Calculations are made using the dose per MU under normalization conditions, \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{upgreek} \\usepackage{mathrsfs} \\setlength{\\oddsidemargin}{-69pt} \\begin{document} }{}$D_0^\\prime $\\end{document}D0′, that is determined for each user's photon and electron beams. For electron beams, the depth of normalization is taken to be the depth of maximum dose along the central axis for the same field incident on a water phantom at the same SSD, where \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{upgreek} \\usepackage{mathrsfs} \\setlength{\\oddsidemargin}{-69pt} \\begin{document} }{}$D_0^\\prime $\\end{document}D0′ = 1 cGy/MU. For photon beams, this task group recommends that a normalization depth of 10 cm be selected, where an energy-dependent \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{upgreek} \\usepackage{mathrsfs} \\setlength{\\oddsidemargin}{-69pt} \\begin{document} }{}$D_0^\\prime $\\end{document}D0′ ≤ 1 cGy/MU is required. This recommendation differs from the more common approach of a normalization depth of dm, with \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{upgreek} \\usepackage{mathrsfs} \\setlength{\\oddsidemargin}{-69pt} \\begin{document} }{}$D_0^\\prime $\\end{document}D0′ = 1 cGy/MU, although both systems are acceptable within the current protocol. For photon beams, the formalism includes the use of blocked fields, physical or dynamic wedges, and (static) multileaf collimation. No formalism is provided for intensity modulated radiation therapy calculations, although some general considerations and a review of current calculation techniques are included. For electron beams, the formalism provides for calculations at the standard and extended SSDs using either an effective SSD or an air-gap correction factor. Example tables and problems are included to illustrate the basic concepts within the presented formalism. PMID:24593704

AAPM and GEC-ESTRO guidelines for image-guided robotic brachytherapy: Report of Task Group 192

DOE Office of Scientific and Technical Information (OSTI.GOV)

Podder, Tarun K., E-mail: tarun.podder@uhhospitals.org; Beaulieu, Luc; Caldwell, Barrett

In the last decade, there have been significant developments into integration of robots and automation tools with brachytherapy delivery systems. These systems aim to improve the current paradigm by executing higher precision and accuracy in seed placement, improving calculation of optimal seed locations, minimizing surgical trauma, and reducing radiation exposure to medical staff. Most of the applications of this technology have been in the implantation of seeds in patients with early-stage prostate cancer. Nevertheless, the techniques apply to any clinical site where interstitial brachytherapy is appropriate. In consideration of the rapid developments in this area, the American Association of Physicistsmore » in Medicine (AAPM) commissioned Task Group 192 to review the state-of-the-art in the field of robotic interstitial brachytherapy. This is a joint Task Group with the Groupe Européen de Curiethérapie-European Society for Radiotherapy and Oncology (GEC-ESTRO). All developed and reported robotic brachytherapy systems were reviewed. Commissioning and quality assurance procedures for the safe and consistent use of these systems are also provided. Manual seed placement techniques with a rigid template have an estimated in vivo accuracy of 3–6 mm. In addition to the placement accuracy, factors such as tissue deformation, needle deviation, and edema may result in a delivered dose distribution that differs from the preimplant or intraoperative plan. However, real-time needle tracking and seed identification for dynamic updating of dosimetry may improve the quality of seed implantation. The AAPM and GEC-ESTRO recommend that robotic systems should demonstrate a spatial accuracy of seed placement ≤1.0 mm in a phantom. This recommendation is based on the current performance of existing robotic brachytherapy systems and propagation of uncertainties. During clinical commissioning, tests should be conducted to ensure that this level of accuracy is achieved. These tests should mimic the real operating procedure as closely as possible. Additional recommendations on robotic brachytherapy systems include display of the operational state; capability of manual override; documented policies for independent check and data verification; intuitive interface displaying the implantation plan and visualization of needle positions and seed locations relative to the target anatomy; needle insertion in a sequential order; robot–clinician and robot–patient interactions robustness, reliability, and safety while delivering the correct dose at the correct site for the correct patient; avoidance of excessive force on radioactive sources; delivery confirmation of the required number or position of seeds; incorporation of a collision avoidance system; system cleaning, decontamination, and sterilization procedures. These recommendations are applicable to end users and manufacturers of robotic brachytherapy systems.« less

WE-E-19A-01: Globalization of Medical Physics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rehani, M; Meghzifene, A; Tsapaki, V

Following successful 2012–2013 International Professional Symposiums as a part of Annual AAPM meetings, representatives of AAPM and International Organization of Medical Physics (IOMP) suggested to make this tradiational Symposium a permanent part of Annual AAPM meetings in future. Following the tradition, this session includes presentations of representatives of AAPM, IOMP, European Federation of Medical Physics (EFOMP), International Atomic Energy Agency (IAEA) and International Center for Theoretical Physics (ICTP). The speakers will cover various aspects of International collaboration such as educational, professional, and scientific issues, as well as help to developing countries. With further developments of medicine and technology and increasedmore » communication with our colleagues overseas, Medical Physics becomes more and more global profession. Use of the same technology, significant progress in medical physics research and developing practical regulations worldwide makes it increasingly useful to organize global collaboration of medical physicists. Several international organizations are tasked to promote such collaboration and provide help to developing countries. Not all AAPM members are fully aware of these international efforts. It is very useful for medical physicists to know about success of our profession in other countries. Different schools present different approaches to the same problem, which allows to find the best solution. By communicating with colleagues overseas, one can learn more than from just reading scientific publications. At this session the attendees will receive a glimpse of International Medical Physics activities. Learning Objectives: Understand the globalization of Medical Physics profession and advantages of collaboration with foreign colleagues. See what role AAPM is playing in establishing contacts with colleagues overseas. Understand the role of IOMP and main directions of its activity. Learn about IAEA and how it helps developing countries. Learn about activity of EFOMP and how can help the global development of Medical Physics. Find out about ICTP and its educational programs.« less

SRT and SBRT: Current practices for QA dosimetry and 3D

NASA Astrophysics Data System (ADS)

Benedict, S. H.; Cai, J.; Libby, B.; Lovelock, M.; Schlesinger, D.; Sheng, K.; Yang, W.

2010-11-01

The major feature that separates stereotactic radiation therapy (cranial SRT) and stereotactic body radiation therapy (SBRT) from conventional radiation treatment is the delivery of large doses in a few fractions which results in a high biological effective dose (BED). In order to minimize the normal tissue toxicity, quality assurance of the conformation of high doses to the target and rapid fall off doses away from the target is critical. The practice of SRT and SBRT therefore requires a high-level of confidence in the accuracy of the entire treatment delivery process. In SRT and SBRT confidence in this accuracy is accomplished by the integration of modern imaging, simulation, treatment planning and delivery technologies into all phases of the treatment process; from treatment simulation and planning and continuing throughout beam delivery. In this report some of the findings of Task group 101 of the AAPM will be presented which outlines the best-practice guidelines for SBRT. The task group report includes a review of the literature to identify reported clinical findings and expected outcomes for this treatment modality. Information in this task group is provided for establishing an SBRT program, including protocols, equipment, resources, and QA procedures.

SU-F-E-15: Initial Experience Implementing a Case Method Teaching Approach to Radiation Oncology Physics Residents, Graduate Students and Doctorate of Medical Physics Students

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gutierrez, A

Purpose: Case Method Teaching approach is a teaching tool used commonly in business school to challenge students with real-world situations—i.e. cases. The students are placed in the role of the decision maker and have to provide a solution based on the multitude of information provided. Specifically, students must develop an ability to quickly make sense of a complex problem, provide a solution incorporating all of the objectives (at time conflicting) and constraints, and communicate that solution in a succinct, professional and effective manner. The validity of the solution is highly dependent on the auxiliary information provided in the case andmore » the basic didactic knowledge of the student. A Case Method Teaching approach was developed and implemented into an on-going course focused on AAPM Task Group reports at UTHSCSA. Methods: A current course at UTHSCSA reviews and discusses 15 AAPM Task Group reports per semester. The course is structured into three topic modules: Imaging QA, Stereotactic Radiotherapy, and Special Patient Measurements—i.e. pacemakers, fetal dose. After a topic module is complete, the students are divided into groups (2–3 people) and are asked to review a case study related to the module topic. Students then provide a solution presented in an executive summary and class presentation. Results: Case studies were created to address each module topic. Through team work and whole-class discussion, a collaborative learning environment was established. Students additionally learned concepts such vendor relations, financial negotiations, capital project management, and competitive strategy. Conclusion: Case Method Teaching approach is an effective teaching tool to further enhance the learning experience of radiation oncology physics students by presenting them with though-provoking dilemmas that require students to distinguish pertinent from peripheral information, formulate strategies and recommendations for action, and confront obstacles to implementation.« less

An Evaluation of Performance Characteristics of Primary Display Devices.

PubMed

Ekpo, Ernest U; McEntee, Mark F

2016-04-01

The aim of this study was to complete a full evaluation of the new EIZO RX850 liquid crystal display and compare it to two currently used medical displays in Australia (EIZO GS510 and Barco MDCG 5121). The American Association of Physicists in Medicine (AAPM) Task Group 18 Quality Control test pattern was used to assess the performance of three high-resolution primary medical displays: EIZO RX850, EIZO GS510, and Barco MDCG 5121. A Konica Minolta spectroradiometer (CS-2000) was used to assess luminance response, non-uniformity, veiling glare, and color uniformity. Qualitative evaluation of noise was also performed. Seven breast lesions were displayed on each monitor and photographed with a calibrated 5.5-MP Olympus E-1 digital SLR camera. ImageJ software was used to sample pixel information from each lesion and surrounding background to calculate their conspicuity index on each of the displays. All monitor fulfilled all AAPM acceptance criteria. The performance characteristics for EIZO RX850, Barco MDCG 5121, and EIZO GS510 respectively were as follows: maximum luminance (490, 500.5, and 413 cd/m(2)), minimum luminance (0.724, 1.170, and 0.92 cd/m(2)), contrast ratio (675:1, 428:1, 449:1), just-noticeable difference index (635, 622, 609), non-uniformity (20, 5.92, and 8.5 %), veiling glare (GR = 2465.6, 720.4, 1249.8), and color uniformity (Δu'v' = +0.003, +0.002, +0.002). All monitors demonstrated low noise levels. The conspicuity index (χ) of the lesions was slightly higher in the EIZO RX850 display. All medical displays fulfilled AAPM performance criteria, and performance characteristics of EIZO RX850 are equal to or better than those of the Barco MDCG 5121 and EIZO GS510 displays.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schiefer, H., E-mail: johann.schiefer@kssg.ch; Peters, S.; Plasswilm, L.

Purpose: For stereotactic radiosurgery, the AAPM Report No. 54 [AAPM Task Group 42 (AAPM, 1995)] requires the overall stability of the isocenter (couch, gantry, and collimator) to be within a 1 mm radius. In reality, a rotating system has no rigid axis and thus no isocenter point which is fixed in space. As a consequence, the isocenter concept is reviewed here. It is the aim to develop a measurement method following the revised definitions. Methods: The mechanical isocenter is defined here by the point which rotates on the shortest path in the room coordinate system. The path is labeled asmore » “isocenter path.” Its center of gravity is assumed to be the mechanical isocenter. Following this definition, an image-based and radiation-free measurement method was developed. Multiple marker pairs in a plane perpendicular to the assumed gantry rotation axis of a linear accelerator are imaged with a smartphone application from several rotation angles. Each marker pair represents an independent measuring system. The room coordinates of the isocenter path and the mechanical isocenter are calculated based on the marker coordinates. The presented measurement method is by this means strictly focused on the mechanical isocenter. Results: The measurement result is available virtually immediately following completion of measurement. When 12 independent measurement systems are evaluated, the standard deviations of the isocenter path points and mechanical isocenter coordinates are 0.02 and 0.002 mm, respectively. Conclusions: The measurement is highly accurate, time efficient, and simple to adapt. It is therefore suitable for regular checks of the mechanical isocenter characteristics of the gantry and collimator rotation axis. When the isocenter path is reproducible and its extent is in the range of the needed geometrical accuracy, it should be taken into account in the planning process. This is especially true for stereotactic treatments and radiosurgery.« less

Toward a standard for the evaluation of PET-Auto-Segmentation methods following the recommendations of AAPM task group No. 211: Requirements and implementation.

PubMed

Berthon, Beatrice; Spezi, Emiliano; Galavis, Paulina; Shepherd, Tony; Apte, Aditya; Hatt, Mathieu; Fayad, Hadi; De Bernardi, Elisabetta; Soffientini, Chiara D; Ross Schmidtlein, C; El Naqa, Issam; Jeraj, Robert; Lu, Wei; Das, Shiva; Zaidi, Habib; Mawlawi, Osama R; Visvikis, Dimitris; Lee, John A; Kirov, Assen S

2017-08-01

The aim of this paper is to define the requirements and describe the design and implementation of a standard benchmark tool for evaluation and validation of PET-auto-segmentation (PET-AS) algorithms. This work follows the recommendations of Task Group 211 (TG211) appointed by the American Association of Physicists in Medicine (AAPM). The recommendations published in the AAPM TG211 report were used to derive a set of required features and to guide the design and structure of a benchmarking software tool. These items included the selection of appropriate representative data and reference contours obtained from established approaches and the description of available metrics. The benchmark was designed in a way that it could be extendable by inclusion of bespoke segmentation methods, while maintaining its main purpose of being a standard testing platform for newly developed PET-AS methods. An example of implementation of the proposed framework, named PETASset, was built. In this work, a selection of PET-AS methods representing common approaches to PET image segmentation was evaluated within PETASset for the purpose of testing and demonstrating the capabilities of the software as a benchmark platform. A selection of clinical, physical, and simulated phantom data, including "best estimates" reference contours from macroscopic specimens, simulation template, and CT scans was built into the PETASset application database. Specific metrics such as Dice Similarity Coefficient (DSC), Positive Predictive Value (PPV), and Sensitivity (S), were included to allow the user to compare the results of any given PET-AS algorithm to the reference contours. In addition, a tool to generate structured reports on the evaluation of the performance of PET-AS algorithms against the reference contours was built. The variation of the metric agreement values with the reference contours across the PET-AS methods evaluated for demonstration were between 0.51 and 0.83, 0.44 and 0.86, and 0.61 and 1.00 for DSC, PPV, and the S metric, respectively. Examples of agreement limits were provided to show how the software could be used to evaluate a new algorithm against the existing state-of-the art. PETASset provides a platform that allows standardizing the evaluation and comparison of different PET-AS methods on a wide range of PET datasets. The developed platform will be available to users willing to evaluate their PET-AS methods and contribute with more evaluation datasets. © 2017 The Authors. Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of Physicists in Medicine.

TU-B-19A-01: Image Registration II: TG132-Quality Assurance for Image Registration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brock, K; Mutic, S

2014-06-15

AAPM Task Group 132 was charged with a review of the current approaches and solutions for image registration in radiotherapy and to provide recommendations for quality assurance and quality control of these clinical processes. As the results of image registration are always used as the input of another process for planning or delivery, it is important for the user to understand and document the uncertainty associate with the algorithm in general and the Result of a specific registration. The recommendations of this task group, which at the time of abstract submission are currently being reviewed by the AAPM, include themore » following components. The user should understand the basic image registration techniques and methods of visualizing image fusion. The disclosure of basic components of the image registration by commercial vendors is critical in this respect. The physicists should perform end-to-end tests of imaging, registration, and planning/treatment systems if image registration is performed on a stand-alone system. A comprehensive commissioning process should be performed and documented by the physicist prior to clinical use of the system. As documentation is important to the safe implementation of this process, a request and report system should be integrated into the clinical workflow. Finally, a patient specific QA practice should be established for efficient evaluation of image registration results. The implementation of these recommendations will be described and illustrated during this educational session. Learning Objectives: Highlight the importance of understanding the image registration techniques used in their clinic. Describe the end-to-end tests needed for stand-alone registration systems. Illustrate a comprehensive commissioning program using both phantom data and clinical images. Describe a request and report system to ensure communication and documentation. Demonstrate an clinically-efficient patient QA practice for efficient evaluation of image registration.« less

Intraoperative radiation therapy using mobile electron linear accelerators: report of AAPM Radiation Therapy Committee Task Group No. 72.

PubMed

Beddar, A Sam; Biggs, Peter J; Chang, Sha; Ezzell, Gary A; Faddegon, Bruce A; Hensley, Frank W; Mills, Michael D

2006-05-01

Intraoperative radiation therapy (IORT) has been customarily performed either in a shielded operating suite located in the operating room (OR) or in a shielded treatment room located within the Department of Radiation Oncology. In both cases, this cancer treatment modality uses stationary linear accelerators. With the development of new technology, mobile linear accelerators have recently become available for IORT. Mobility offers flexibility in treatment location and is leading to a renewed interest in IORT. These mobile accelerator units, which can be transported any day of use to almost any location within a hospital setting, are assembled in a nondedicated environment and used to deliver IORT. Numerous aspects of the design of these new units differ from that of conventional linear accelerators. The scope of this Task Group (TG-72) will focus on items that particularly apply to mobile IORT electron systems. More specifically, the charges to this Task Group are to (i) identify the key differences between stationary and mobile electron linear accelerators used for IORT, (ii) describe and recommend the implementation of an IORT program within the OR environment, (iii) present and discuss radiation protection issues and consequences of working within a nondedicated radiotherapy environment, (iv) describe and recommend the acceptance and machine commissioning of items that are specific to mobile electron linear accelerators, and (v) design and recommend an efficient quality assurance program for mobile systems.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rivard, M.

With the recent introduction of heterogeneity correction algorithms for brachytherapy, the AAPM community is still unclear on how to commission and implement these into clinical practice. The recently-published AAPM TG-186 report discusses important issues for clinical implementation of these algorithms. A charge of the AAPM-ESTRO-ABG Working Group on MBDCA in Brachytherapy (WGMBDCA) is the development of a set of well-defined test case plans, available as references in the software commissioning process to be performed by clinical end-users. In this practical medical physics course, specific examples on how to perform the commissioning process are presented, as well as descriptions of themore » clinical impact from recent literature reporting comparisons of TG-43 and heterogeneity-based dosimetry. Learning Objectives: Identify key clinical applications needing advanced dose calculation in brachytherapy. Review TG-186 and WGMBDCA guidelines, commission process, and dosimetry benchmarks. Evaluate clinical cases using commercially available systems and compare to TG-43 dosimetry.« less

Comparison of AAPM Addendum to TG-51, IAEA TRS-398, and JSMP 12: Calibration of photon beams in water.

PubMed

Kinoshita, Naoki; Oguchi, Hiroshi; Nishimoto, Yasuhiro; Adachi, Toshiki; Shioura, Hiroki; Kimura, Hirohiko; Doi, Kunio

2017-09-01

The American Association of Physicists in Medicine (AAPM) Working Group on TG-51 published an Addendum to the AAPM's TG-51 protocol (Addendum to TG-51) in 2014, and the Japan Society of Medical Physics (JSMP) published a new dosimetry protocol JSMP 12 in 2012. In this study, we compared the absorbed dose to water determined at the reference depth for high-energy photon beams following the recommendations given in AAPM TG-51 and the Addendum to TG-51, IAEA TRS-398, and JSMP 12. This study was performed using measurements with flattened photon beams with nominal energies of 6 and 10 MV. Three widely used ionization chambers with different compositions, Exradin A12, PTW 30013, and IBA FC65-P, were employed. Fully corrected charge readings obtained for the three chambers according to AAPM TG-51 and the Addendum to TG-51, which included the correction for the radiation beam profile (P rp ), showed variations of 0.2% and 0.3% at 6 and 10 MV, respectively, from the readings corresponding to IAEA TRS-398 and JSMP 12. The values for the beam quality conversion factor k Q obtained according to the three protocols agreed within 0.5%; the only exception was a 0.6% difference between the results obtained at 10 MV for Exradin A12 according to IAEA TRS-398 and AAPM TG-51 and the Addendum to TG-51. Consequently, the values for the absorbed dose to water obtained for the three protocols agreed within 0.4%; the only exception was a 0.6% difference between the values obtained at 10 MV for PTW 30013 according to AAPM TG-51 and the Addendum to TG-51, and JSMP 12. While the difference in the absorbed dose to water determined by the three protocols depends on the k Q and P rp values, the absorbed dose to water obtained according to the three protocols agrees within the relative uncertainties for the three protocols. © 2017 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of Physicists in Medicine.

MO-FG-BRB-00: AAPM Presidential Debate [medical physics education

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

Building on the energy and excitement of Washington DC in a presidential election year, AAPM will host its own Presidential Debate to better understand the views of the AAPM membership! Past presidents of the AAPM, Drs. Bayouth, Hazle, Herman, and Seibert, will debate hot topics in medical physics including issues facing education, professional practice, and the advancement of science. The moderators, Drs. Brock and Stern, will also draw in topics from Point-Counterpoint articles from the Medical Physics Journals. Wrapping up the debate, the audience will have the opportunity to question the candidates in a town hall format. At the conclusionmore » of this lively debate, the winner will be decided by the audience, so bring your Audience Response Units! Be part of Medical Physics - Decision 2016! Learning Objectives: Understand AAPM members’ views and opinions on issues facing medical physics education Learn AAPM members’ views and opinions on issues facing professional practice Identify AAPM members’ view and opinions on issues facing the advancement of science in medical physics J. Bayouth, Funding support from NCI;Scientific Advisory Board member - ViewRay.« less

WE-F-201-00: Practical Guidelines for Commissioning Advanced Brachytherapy Dose Calculation Algorithms

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

2015-06-15

With the recent introduction of heterogeneity correction algorithms for brachytherapy, the AAPM community is still unclear on how to commission and implement these into clinical practice. The recently-published AAPM TG-186 report discusses important issues for clinical implementation of these algorithms. A charge of the AAPM-ESTRO-ABG Working Group on MBDCA in Brachytherapy (WGMBDCA) is the development of a set of well-defined test case plans, available as references in the software commissioning process to be performed by clinical end-users. In this practical medical physics course, specific examples on how to perform the commissioning process are presented, as well as descriptions of themore » clinical impact from recent literature reporting comparisons of TG-43 and heterogeneity-based dosimetry. Learning Objectives: Identify key clinical applications needing advanced dose calculation in brachytherapy. Review TG-186 and WGMBDCA guidelines, commission process, and dosimetry benchmarks. Evaluate clinical cases using commercially available systems and compare to TG-43 dosimetry.« less

WE-F-201-03: Evaluate Clinical Cases Using Commercially Available Systems and Compare to TG-43 Dosimetry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Beaulieu, L.

With the recent introduction of heterogeneity correction algorithms for brachytherapy, the AAPM community is still unclear on how to commission and implement these into clinical practice. The recently-published AAPM TG-186 report discusses important issues for clinical implementation of these algorithms. A charge of the AAPM-ESTRO-ABG Working Group on MBDCA in Brachytherapy (WGMBDCA) is the development of a set of well-defined test case plans, available as references in the software commissioning process to be performed by clinical end-users. In this practical medical physics course, specific examples on how to perform the commissioning process are presented, as well as descriptions of themore » clinical impact from recent literature reporting comparisons of TG-43 and heterogeneity-based dosimetry. Learning Objectives: Identify key clinical applications needing advanced dose calculation in brachytherapy. Review TG-186 and WGMBDCA guidelines, commission process, and dosimetry benchmarks. Evaluate clinical cases using commercially available systems and compare to TG-43 dosimetry.« less

Antiangiogenic effects of AA-PMe on HUVECs in vitro and zebrafish in vivo

PubMed Central

Xiao, Qi; Zhou, Yachun; Wei, Yingjie; Gong, Zhunan

2018-01-01

Angiogenesis plays a vital role in many physiological and pathological processes and several diseases are connected with its dysregulation. Asiatic acid (AA) has demonstrated anticancer properties and we suspect this might be attributable to an effect on angio-genesis. A modified derivative of AA, N-(2α,3β,23-acetoxyurs-12-en-28-oyl)-L-proline methyl ester (AA-PMe), has improved efficacy over its parent compound, but its effect on blood vessel development remains unclear. Methods In this study, we investigated the antiangiogenic activity of AA and AA-PMe in zebrafish embryos and human umbilical vein endothelial cells (HUVECs). First of all, we treated HUVECs with increasing concentrations of AA-PMe or AA, with or without vascular endothelial growth factor (VEGF) present, and assessed cell viability, tube formation, and cell migration and invasion. Quantitative real-time polymerase chain reaction and Western blot analysis were later used to determine the role of vascular endothelial growth factor receptor 2 (VEGFR2)-mediated signaling in AA-PMe inhibition of angiogenesis. We extended these studies to follow angiogenesis using Tg(fli:EGFP) transgenic zebrafish embryos. For these experiments, embryos were treated with varying concentrations of AA-PMe or AA from 24 to 72 hours postfertilization prior to morphological observation, angiogenesis assessment, and endogenous alkaline phosphatase assay. VEGFR2 expression in whole embryos following AA-PMe treatment was also determined. Results We found AA-PMe decreased cell viability and inhibited migration and tube formation in a dose-dependent manner in HUVECs. Similarly, AA-PMe disrupted the formation of intersegmental vessels, the dorsal aorta, and the posterior cardinal vein in zebrafish embryos. Both in vitro and in vivo AA-PMe surpassed AA in its ability to block angiogenesis by suppressing VEGF-induced phosphorylation of VEGFR2 and disrupting downstream extracellular regulated protein kinase and AKT signaling. Conclusion For the first time, this study reveals that AA-PMe acts as a potent VEGFR2 kinase inhibitor and exerts powerful antiangiogenic activity, suggesting it to be a promising therapeutic candidate for further research. PMID:29670362

Antiangiogenic effects of AA-PMe on HUVECs in vitro and zebrafish in vivo.

PubMed

Jing, Yue; Wang, Gang; Xiao, Qi; Zhou, Yachun; Wei, Yingjie; Gong, Zhunan

2018-01-01

Angiogenesis plays a vital role in many physiological and pathological processes and several diseases are connected with its dysregulation. Asiatic acid (AA) has demonstrated anticancer properties and we suspect this might be attributable to an effect on angio-genesis. A modified derivative of AA, N-(2α,3β,23-acetoxyurs-12-en-28-oyl)-L-proline methyl ester (AA-PMe), has improved efficacy over its parent compound, but its effect on blood vessel development remains unclear. In this study, we investigated the antiangiogenic activity of AA and AA-PMe in zebrafish embryos and human umbilical vein endothelial cells (HUVECs). First of all, we treated HUVECs with increasing concentrations of AA-PMe or AA, with or without vascular endothelial growth factor (VEGF) present, and assessed cell viability, tube formation, and cell migration and invasion. Quantitative real-time polymerase chain reaction and Western blot analysis were later used to determine the role of vascular endothelial growth factor receptor 2 (VEGFR2)-mediated signaling in AA-PMe inhibition of angiogenesis. We extended these studies to follow angiogenesis using Tg(fli:EGFP) transgenic zebrafish embryos. For these experiments, embryos were treated with varying concentrations of AA-PMe or AA from 24 to 72 hours postfertilization prior to morphological observation, angiogenesis assessment, and endogenous alkaline phosphatase assay. VEGFR2 expression in whole embryos following AA-PMe treatment was also determined. We found AA-PMe decreased cell viability and inhibited migration and tube formation in a dose-dependent manner in HUVECs. Similarly, AA-PMe disrupted the formation of intersegmental vessels, the dorsal aorta, and the posterior cardinal vein in zebrafish embryos. Both in vitro and in vivo AA-PMe surpassed AA in its ability to block angiogenesis by suppressing VEGF-induced phosphorylation of VEGFR2 and disrupting downstream extracellular regulated protein kinase and AKT signaling. For the first time, this study reveals that AA-PMe acts as a potent VEGFR2 kinase inhibitor and exerts powerful antiangiogenic activity, suggesting it to be a promising therapeutic candidate for further research.

Evaluation of cassette-based digital radiography detectors using standardized image quality metrics: AAPM TG-150 Draft Image Detector Tests.

PubMed

Li, Guang; Greene, Travis C; Nishino, Thomas K; Willis, Charles E

2016-09-08

The purpose of this study was to evaluate several of the standardized image quality metrics proposed by the American Association of Physics in Medicine (AAPM) Task Group 150. The task group suggested region-of-interest (ROI)-based techniques to measure nonuniformity, minimum signal-to-noise ratio (SNR), number of anomalous pixels, and modulation transfer function (MTF). This study evaluated the effects of ROI size and layout on the image metrics by using four different ROI sets, assessed result uncertainty by repeating measurements, and compared results with two commercially available quality control tools, namely the Carestream DIRECTVIEW Total Quality Tool (TQT) and the GE Healthcare Quality Assurance Process (QAP). Seven Carestream DRX-1C (CsI) detectors on mobile DR systems and four GE FlashPad detectors in radiographic rooms were tested. Images were analyzed using MATLAB software that had been previously validated and reported. Our values for signal and SNR nonuniformity and MTF agree with values published by other investigators. Our results show that ROI size affects nonuniformity and minimum SNR measurements, but not detection of anomalous pixels. Exposure geometry affects all tested image metrics except for the MTF. TG-150 metrics in general agree with the TQT, but agree with the QAP only for local and global signal nonuniformity. The difference in SNR nonuniformity and MTF values between the TG-150 and QAP may be explained by differences in the calculation of noise and acquisition beam quality, respectively. TG-150's SNR nonuniformity metrics are also more sensitive to detector nonuniformity compared to the QAP. Our results suggest that fixed ROI size should be used for consistency because nonuniformity metrics depend on ROI size. Ideally, detector tests should be performed at the exact calibration position. If not feasible, a baseline should be established from the mean of several repeated measurements. Our study indicates that the TG-150 tests can be used as an independent standardized procedure for detector performance assessment. © 2016 The Authors.

Evaluation of cassette‐based digital radiography detectors using standardized image quality metrics: AAPM TG‐150 Draft Image Detector Tests

PubMed Central

Greene, Travis C.; Nishino, Thomas K.; Willis, Charles E.

2016-01-01

The purpose of this study was to evaluate several of the standardized image quality metrics proposed by the American Association of Physics in Medicine (AAPM) Task Group 150. The task group suggested region‐of‐interest (ROI)‐based techniques to measure nonuniformity, minimum signal‐to‐noise ratio (SNR), number of anomalous pixels, and modulation transfer function (MTF). This study evaluated the effects of ROI size and layout on the image metrics by using four different ROI sets, assessed result uncertainty by repeating measurements, and compared results with two commercially available quality control tools, namely the Carestream DIRECTVIEW Total Quality Tool (TQT) and the GE Healthcare Quality Assurance Process (QAP). Seven Carestream DRX‐1C (CsI) detectors on mobile DR systems and four GE FlashPad detectors in radiographic rooms were tested. Images were analyzed using MATLAB software that had been previously validated and reported. Our values for signal and SNR nonuniformity and MTF agree with values published by other investigators. Our results show that ROI size affects nonuniformity and minimum SNR measurements, but not detection of anomalous pixels. Exposure geometry affects all tested image metrics except for the MTF. TG‐150 metrics in general agree with the TQT, but agree with the QAP only for local and global signal nonuniformity. The difference in SNR nonuniformity and MTF values between the TG‐150 and QAP may be explained by differences in the calculation of noise and acquisition beam quality, respectively. TG‐150's SNR nonuniformity metrics are also more sensitive to detector nonuniformity compared to the QAP. Our results suggest that fixed ROI size should be used for consistency because nonuniformity metrics depend on ROI size. Ideally, detector tests should be performed at the exact calibration position. If not feasible, a baseline should be established from the mean of several repeated measurements. Our study indicates that the TG‐150 tests can be used as an independent standardized procedure for detector performance assessment. PACS number(s): 87.57.‐s, 87.57.C PMID:27685102

Off-label use of medical products in radiation therapy: Summary of the Report of AAPM Task Group No. 121

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thomadsen, Bruce R.; Thompson, Heaton H. II; Jani, Shirish K.

Medical products (devices, drugs, or biologics) contain information in their labeling regarding the manner in which the manufacturer has determined that the products can be used in a safe and effective manner. The Food and Drug Administration (FDA) approves medical products for use for these specific indications which are part of the medical product's labeling. When medical products are used in a manner not specified in the labeling, it is commonly referred to as off-label use. The practice of medicine allows for this off-label use to treat individual patients, but the ethical and legal implications for such unapproved use canmore » be confusing. Although the responsibility and, ultimately, the liability for off-label use often rests with the prescribing physician, medical physicists and others are also responsible for the safe and proper use of the medical products. When these products are used for purposes other than which they were approved, it is important for medical physicists to understand their responsibilities. In the United States, medical products can only be marketed if officially cleared, approved, or licensed by the FDA; they can be used if they are not subject to or specifically exempt from FDA regulations, or if they are being used in research with the appropriate regulatory safeguards. Medical devices are either cleared or approved by FDA's Center for Devices and Radiological Health. Drugs are approved by FDA's Center for Drug Evaluation and Research, and biological products such as vaccines or blood are licensed under a biologics license agreement by FDA's Center for Biologics Evaluation and Research. For the purpose of this report, the process by which the FDA eventually clears, approves, or licenses such products for marketing in the United States will be referred to as approval. This report summarizes the various ways medical products, primarily medical devices, can legally be brought to market in the United States, and includes a discussion of the approval process, along with manufacturers' responsibilities, labeling, marketing and promotion, and off-label use. This is an educational and descriptive report and does not contain prescriptive recommendations. This report addresses the role of the medical physicist in clinical situations involving off-label use. Case studies in radiation therapy are presented. Any mention of commercial products is for identification only; it does not imply recommendations or endorsements of any of the authors or the AAPM. The full report, containing extensive background on off-label use with several appendices, is available on the AAPM website (http://www.aapm.org/pubs/reports/).« less

Ongoing quality control in digital radiography: Report of AAPM Imaging Physics Committee Task Group 151.

PubMed

Jones, A Kyle; Heintz, Philip; Geiser, William; Goldman, Lee; Jerjian, Khachig; Martin, Melissa; Peck, Donald; Pfeiffer, Douglas; Ranger, Nicole; Yorkston, John

2015-11-01

Quality control (QC) in medical imaging is an ongoing process and not just a series of infrequent evaluations of medical imaging equipment. The QC process involves designing and implementing a QC program, collecting and analyzing data, investigating results that are outside the acceptance levels for the QC program, and taking corrective action to bring these results back to an acceptable level. The QC process involves key personnel in the imaging department, including the radiologist, radiologic technologist, and the qualified medical physicist (QMP). The QMP performs detailed equipment evaluations and helps with oversight of the QC program, the radiologic technologist is responsible for the day-to-day operation of the QC program. The continued need for ongoing QC in digital radiography has been highlighted in the scientific literature. The charge of this task group was to recommend consistency tests designed to be performed by a medical physicist or a radiologic technologist under the direction of a medical physicist to identify problems with an imaging system that need further evaluation by a medical physicist, including a fault tree to define actions that need to be taken when certain fault conditions are identified. The focus of this final report is the ongoing QC process, including rejected image analysis, exposure analysis, and artifact identification. These QC tasks are vital for the optimal operation of a department performing digital radiography.

Ongoing quality control in digital radiography: Report of AAPM Imaging Physics Committee Task Group 151

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jones, A. Kyle, E-mail: kyle.jones@mdanderson.org; Geiser, William; Heintz, Philip

Quality control (QC) in medical imaging is an ongoing process and not just a series of infrequent evaluations of medical imaging equipment. The QC process involves designing and implementing a QC program, collecting and analyzing data, investigating results that are outside the acceptance levels for the QC program, and taking corrective action to bring these results back to an acceptable level. The QC process involves key personnel in the imaging department, including the radiologist, radiologic technologist, and the qualified medical physicist (QMP). The QMP performs detailed equipment evaluations and helps with oversight of the QC program, the radiologic technologist ismore » responsible for the day-to-day operation of the QC program. The continued need for ongoing QC in digital radiography has been highlighted in the scientific literature. The charge of this task group was to recommend consistency tests designed to be performed by a medical physicist or a radiologic technologist under the direction of a medical physicist to identify problems with an imaging system that need further evaluation by a medical physicist, including a fault tree to define actions that need to be taken when certain fault conditions are identified. The focus of this final report is the ongoing QC process, including rejected image analysis, exposure analysis, and artifact identification. These QC tasks are vital for the optimal operation of a department performing digital radiography.« less

AA-PMe, a novel asiatic acid derivative, induces apoptosis and suppresses proliferation, migration, and invasion of gastric cancer cells.

PubMed

Jing, Yue; Wang, Gang; Ge, Ying; Xu, Minjie; Tang, Shuainan; Gong, Zhunan

2016-01-01

Asiatic acid (AA; 2α,3β,23-trihydroxyurs-12-ene-28-oic acid) is widely used for medicinal purposes in many Asian countries due to its various bioactivities. A series of AA derivatives has been synthesized in attempts to improve its therapeutic potencies. Herein we investigated the anti-tumor activities of N-(2α,3β,23-acetoxyurs-12-en-28-oyl)-l-proline methyl ester (AA-PMe), a novel AA derivative. AA-PMe exhibited a stronger anti-cancer activity than its parent compound AA. AA-PMe inhibited the proliferation of SGC7901 and HGC27 human gastric cancer cells in a dose-dependent manner but had no significant toxicity in human gastric mucosa epithelial cells (GES-1). AA-PMe induced cell cycle arrest in G0/G1 phase and blocked G1-S transition, which correlated well with marked decreases in levels of cyclin D1, cyclin-dependent kinase CKD4, and phosphorylated retinoblastoma protein, and increase in cyclin-dependent kinase inhibitor P15. Further, AA-PMe induced apoptosis of human gastric cancer cells by affecting Bcl-2, Bax, c-Myc, and caspase-3. Moreover, AA-PMe suppressed the migration and invasion of human gastric cancer cells (SGC7901 and HGC27) cells by downregulating the expression of MMP-2 and MMP-9. Overall, this study investigated the potential anti-cancer activities of AA-PMe including inducing apoptosis and suppressing proliferation, migration and invasion of gastric cancer cells, as well as the underlying mechanisms, suggesting that AA-PMe is a promising anti-cancer drug candidate in gastric cancer therapy.

AA-PMe, a novel asiatic acid derivative, induces apoptosis and suppresses proliferation, migration, and invasion of gastric cancer cells

PubMed Central

Jing, Yue; Wang, Gang; Ge, Ying; Xu, Minjie; Tang, Shuainan; Gong, Zhunan

2016-01-01

Asiatic acid (AA; 2α,3β,23-trihydroxyurs-12-ene-28-oic acid) is widely used for medicinal purposes in many Asian countries due to its various bioactivities. A series of AA derivatives has been synthesized in attempts to improve its therapeutic potencies. Herein we investigated the anti-tumor activities of N-(2α,3β,23-acetoxyurs-12-en-28-oyl)-l-proline methyl ester (AA-PMe), a novel AA derivative. AA-PMe exhibited a stronger anti-cancer activity than its parent compound AA. AA-PMe inhibited the proliferation of SGC7901 and HGC27 human gastric cancer cells in a dose-dependent manner but had no significant toxicity in human gastric mucosa epithelial cells (GES-1). AA-PMe induced cell cycle arrest in G0/G1 phase and blocked G1-S transition, which correlated well with marked decreases in levels of cyclin D1, cyclin-dependent kinase CKD4, and phosphorylated retinoblastoma protein, and increase in cyclin-dependent kinase inhibitor P15. Further, AA-PMe induced apoptosis of human gastric cancer cells by affecting Bcl-2, Bax, c-Myc, and caspase-3. Moreover, AA-PMe suppressed the migration and invasion of human gastric cancer cells (SGC7901 and HGC27) cells by downregulating the expression of MMP-2 and MMP-9. Overall, this study investigated the potential anti-cancer activities of AA-PMe including inducing apoptosis and suppressing proliferation, migration and invasion of gastric cancer cells, as well as the underlying mechanisms, suggesting that AA-PMe is a promising anti-cancer drug candidate in gastric cancer therapy. PMID:27073325

WE-DE-209-01: Dosimetric Benefits of DIBH

DOE Office of Scientific and Technical Information (OSTI.GOV)

Howell, R.

Breast radiation therapy is associated with some risk of lung toxicity as well as cardiac toxicity for left-sided cases. Radiation doses to the lung and heart can be reduced by using the deep inspiration breath hold (DIBH) technique, in which the patient is simulated and treated during the deep inspiration phase of the breathing cycle. During DIBH, the heart is usually displaced posteriorly, inferiorly, and to the right, effectively expanding the distance between the heart and the breast/chest wall. As a result, the distance between the medial treatment field border and heart/lung is increased. Also, in a majority of DIBHmore » patients, the air drawn into the thoracic cavity increases the total lung volume. The DIBH was discussed by an AAPM Task Group 10 years ago in the AAPM TG 76 report. However, DIBH is still not the standard of care in many clinics, which may be partially due to challenges associated with its implementation. Therefore, this seccion will focus primarily on how to clinically implement four different DIBH techniques: (1) Active Breathing Control, (2) Spirometric Motion Management, (3) 3D Surface Image-Guided, and (4) Self-held Breath Control with Respiratory Monitoring and Feedback Guidance. Learning Objectives: Describe the physical displacement of the heart and the change in lung volume during DIBH and discuss dosimetric consequences of those changes. Provide an overview of the technical aspects. Describe work flow for patient simulation and treatment. Give an overview of commissioning and routine. Provide practical tips for clinical implementation.« less

WE-DE-209-02: Active Breathing Control

DOE Office of Scientific and Technical Information (OSTI.GOV)

Comsa, D.

Breast radiation therapy is associated with some risk of lung toxicity as well as cardiac toxicity for left-sided cases. Radiation doses to the lung and heart can be reduced by using the deep inspiration breath hold (DIBH) technique, in which the patient is simulated and treated during the deep inspiration phase of the breathing cycle. During DIBH, the heart is usually displaced posteriorly, inferiorly, and to the right, effectively expanding the distance between the heart and the breast/chest wall. As a result, the distance between the medial treatment field border and heart/lung is increased. Also, in a majority of DIBHmore » patients, the air drawn into the thoracic cavity increases the total lung volume. The DIBH was discussed by an AAPM Task Group 10 years ago in the AAPM TG 76 report. However, DIBH is still not the standard of care in many clinics, which may be partially due to challenges associated with its implementation. Therefore, this seccion will focus primarily on how to clinically implement four different DIBH techniques: (1) Active Breathing Control, (2) Spirometric Motion Management, (3) 3D Surface Image-Guided, and (4) Self-held Breath Control with Respiratory Monitoring and Feedback Guidance. Learning Objectives: Describe the physical displacement of the heart and the change in lung volume during DIBH and discuss dosimetric consequences of those changes. Provide an overview of the technical aspects. Describe work flow for patient simulation and treatment. Give an overview of commissioning and routine. Provide practical tips for clinical implementation.« less

WE-DE-209-03: Spirometric Motion Management System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hadley, S.

Breast radiation therapy is associated with some risk of lung toxicity as well as cardiac toxicity for left-sided cases. Radiation doses to the lung and heart can be reduced by using the deep inspiration breath hold (DIBH) technique, in which the patient is simulated and treated during the deep inspiration phase of the breathing cycle. During DIBH, the heart is usually displaced posteriorly, inferiorly, and to the right, effectively expanding the distance between the heart and the breast/chest wall. As a result, the distance between the medial treatment field border and heart/lung is increased. Also, in a majority of DIBHmore » patients, the air drawn into the thoracic cavity increases the total lung volume. The DIBH was discussed by an AAPM Task Group 10 years ago in the AAPM TG 76 report. However, DIBH is still not the standard of care in many clinics, which may be partially due to challenges associated with its implementation. Therefore, this seccion will focus primarily on how to clinically implement four different DIBH techniques: (1) Active Breathing Control, (2) Spirometric Motion Management, (3) 3D Surface Image-Guided, and (4) Self-held Breath Control with Respiratory Monitoring and Feedback Guidance. Learning Objectives: Describe the physical displacement of the heart and the change in lung volume during DIBH and discuss dosimetric consequences of those changes. Provide an overview of the technical aspects. Describe work flow for patient simulation and treatment. Give an overview of commissioning and routine. Provide practical tips for clinical implementation.« less

42 CFR 37.10 - Standards incorporated by reference.

Code of Federal Regulations, 2013 CFR

2013-10-01

... Department, Medical Physics Publishing, 4513 Vernon Blvd., Madison, WI 53705, http://www.aapm.org/pubs... Automatic Exposure Control Devices, published by the American Institute of Physics for AAPM, January 1985... Institute of Physics, July 1990, into § 37.44(g). (4) AAPM Report No. 74, Quality Control in Diagnostic...

42 CFR 37.10 - Standards incorporated by reference.

Code of Federal Regulations, 2012 CFR

2012-10-01

... Department, Medical Physics Publishing, 4513 Vernon Blvd., Madison, WI 53705, http://www.aapm.org/pubs... Automatic Exposure Control Devices, published by the American Institute of Physics for AAPM, January 1985... Institute of Physics, July 1990, into § 37.44(g). (4) AAPM Report No. 74, Quality Control in Diagnostic...

Anniversary paper. Development of x-ray computed tomography: the role of medical physics and AAPM from the 1970s to present.

PubMed

Pan, Xiaochuan; Siewerdsen, Jeffrey; La Riviere, Patrick J; Kalender, Willi A

2008-08-01

The AAPM, through its members, meetings, and its flagship journal Medical Physics, has played an important role in the development and growth of x-ray tomography in the last 50 years. From a spate of early articles in the 1970s characterizing the first commercial computed tomography (CT) scanners through the "slice wars" of the 1990s and 2000s, the history of CT and related techniques such as tomosynthesis can readily be traced through the pages of Medical Physics and the annals of the AAPM and RSNA/AAPM Annual Meetings. In this article, the authors intend to give a brief review of the role of Medical Physics and the AAPM in CT and tomosynthesis imaging over the last few decades.

42 CFR 37.10 - Standards incorporated by reference.

Code of Federal Regulations, 2014 CFR

2014-10-01

... Association of Physicists in Medicine, Order Department, Medical Physics Publishing, 4513 Vernon Blvd... of Physics for AAPM, January 1985, into §§ 37.42(h) and 37.44(g). (3) AAPM Report No. 31... Committee, published by the American Institute of Physics, July 1990, into § 37.44(g). (4) AAPM Report No...

MO-FG-BRB-02: Debater [medical physics education

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hazle, J.

Building on the energy and excitement of Washington DC in a presidential election year, AAPM will host its own Presidential Debate to better understand the views of the AAPM membership! Past presidents of the AAPM, Drs. Bayouth, Hazle, Herman, and Seibert, will debate hot topics in medical physics including issues facing education, professional practice, and the advancement of science. The moderators, Drs. Brock and Stern, will also draw in topics from Point-Counterpoint articles from the Medical Physics Journals. Wrapping up the debate, the audience will have the opportunity to question the candidates in a town hall format. At the conclusionmore » of this lively debate, the winner will be decided by the audience, so bring your Audience Response Units! Be part of Medical Physics - Decision 2016! Learning Objectives: Understand AAPM members’ views and opinions on issues facing medical physics education Learn AAPM members’ views and opinions on issues facing professional practice Identify AAPM members’ view and opinions on issues facing the advancement of science in medical physics J. Bayouth, Funding support from NCI;Scientific Advisory Board member - ViewRay.« less

MO-FG-BRB-04: Debater [Medical physics education

DOE Office of Scientific and Technical Information (OSTI.GOV)

Seibert, J.

Building on the energy and excitement of Washington DC in a presidential election year, AAPM will host its own Presidential Debate to better understand the views of the AAPM membership! Past presidents of the AAPM, Drs. Bayouth, Hazle, Herman, and Seibert, will debate hot topics in medical physics including issues facing education, professional practice, and the advancement of science. The moderators, Drs. Brock and Stern, will also draw in topics from Point-Counterpoint articles from the Medical Physics Journals. Wrapping up the debate, the audience will have the opportunity to question the candidates in a town hall format. At the conclusionmore » of this lively debate, the winner will be decided by the audience, so bring your Audience Response Units! Be part of Medical Physics - Decision 2016! Learning Objectives: Understand AAPM members’ views and opinions on issues facing medical physics education Learn AAPM members’ views and opinions on issues facing professional practice Identify AAPM members’ view and opinions on issues facing the advancement of science in medical physics J. Bayouth, Funding support from NCI;Scientific Advisory Board member - ViewRay.« less

MO-FG-BRB-01: Debater [medical physics education

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bayouth, J.

Building on the energy and excitement of Washington DC in a presidential election year, AAPM will host its own Presidential Debate to better understand the views of the AAPM membership! Past presidents of the AAPM, Drs. Bayouth, Hazle, Herman, and Seibert, will debate hot topics in medical physics including issues facing education, professional practice, and the advancement of science. The moderators, Drs. Brock and Stern, will also draw in topics from Point-Counterpoint articles from the Medical Physics Journals. Wrapping up the debate, the audience will have the opportunity to question the candidates in a town hall format. At the conclusionmore » of this lively debate, the winner will be decided by the audience, so bring your Audience Response Units! Be part of Medical Physics - Decision 2016! Learning Objectives: Understand AAPM members’ views and opinions on issues facing medical physics education Learn AAPM members’ views and opinions on issues facing professional practice Identify AAPM members’ view and opinions on issues facing the advancement of science in medical physics J. Bayouth, Funding support from NCI;Scientific Advisory Board member - ViewRay.« less

MO-FG-BRB-03: Debater [medical physics education

DOE Office of Scientific and Technical Information (OSTI.GOV)

Herman, M.

Building on the energy and excitement of Washington DC in a presidential election year, AAPM will host its own Presidential Debate to better understand the views of the AAPM membership! Past presidents of the AAPM, Drs. Bayouth, Hazle, Herman, and Seibert, will debate hot topics in medical physics including issues facing education, professional practice, and the advancement of science. The moderators, Drs. Brock and Stern, will also draw in topics from Point-Counterpoint articles from the Medical Physics Journals. Wrapping up the debate, the audience will have the opportunity to question the candidates in a town hall format. At the conclusionmore » of this lively debate, the winner will be decided by the audience, so bring your Audience Response Units! Be part of Medical Physics - Decision 2016! Learning Objectives: Understand AAPM members’ views and opinions on issues facing medical physics education Learn AAPM members’ views and opinions on issues facing professional practice Identify AAPM members’ view and opinions on issues facing the advancement of science in medical physics J. Bayouth, Funding support from NCI;Scientific Advisory Board member - ViewRay.« less

Anniversary Paper: Development of x-ray computed tomography: The role of Medical Physics and AAPM from the 1970s to present

PubMed Central

Pan, Xiaochuan; Siewerdsen, Jeffrey; La Riviere, Patrick J.; Kalender, Willi A.

2008-01-01

The AAPM, through its members, meetings, and its flagship journal Medical Physics, has played an important role in the development and growth of x-ray tomography in the last 50 years. From a spate of early articles in the 1970s characterizing the first commercial computed tomography (CT) scanners through the “slice wars” of the 1990s and 2000s, the history of CT and related techniques such as tomosynthesis can readily be traced through the pages of Medical Physics and the annals of the AAPM and RSNA/AAPM Annual Meetings. In this article, the authors intend to give a brief review of the role of Medical Physics and the AAPM in CT and tomosynthesis imaging over the last few decades. PMID:18777932

Dose calculation for photon-emitting brachytherapy sources with average energy higher than 50 keV: report of the AAPM and ESTRO.

PubMed

Perez-Calatayud, Jose; Ballester, Facundo; Das, Rupak K; Dewerd, Larry A; Ibbott, Geoffrey S; Meigooni, Ali S; Ouhib, Zoubir; Rivard, Mark J; Sloboda, Ron S; Williamson, Jeffrey F

2012-05-01

Recommendations of the American Association of Physicists in Medicine (AAPM) and the European Society for Radiotherapy and Oncology (ESTRO) on dose calculations for high-energy (average energy higher than 50 keV) photon-emitting brachytherapy sources are presented, including the physical characteristics of specific (192)Ir, (137)Cs, and (60)Co source models. This report has been prepared by the High Energy Brachytherapy Source Dosimetry (HEBD) Working Group. This report includes considerations in the application of the TG-43U1 formalism to high-energy photon-emitting sources with particular attention to phantom size effects, interpolation accuracy dependence on dose calculation grid size, and dosimetry parameter dependence on source active length. Consensus datasets for commercially available high-energy photon sources are provided, along with recommended methods for evaluating these datasets. Recommendations on dosimetry characterization methods, mainly using experimental procedures and Monte Carlo, are established and discussed. Also included are methodological recommendations on detector choice, detector energy response characterization and phantom materials, and measurement specification methodology. Uncertainty analyses are discussed and recommendations for high-energy sources without consensus datasets are given. Recommended consensus datasets for high-energy sources have been derived for sources that were commercially available as of January 2010. Data are presented according to the AAPM TG-43U1 formalism, with modified interpolation and extrapolation techniques of the AAPM TG-43U1S1 report for the 2D anisotropy function and radial dose function.

WE-DE-209-05: Self-Held Breath Control with Respiratory Monitoring and Feedback Guidance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gifford, K.

Breast radiation therapy is associated with some risk of lung toxicity as well as cardiac toxicity for left-sided cases. Radiation doses to the lung and heart can be reduced by using the deep inspiration breath hold (DIBH) technique, in which the patient is simulated and treated during the deep inspiration phase of the breathing cycle. During DIBH, the heart is usually displaced posteriorly, inferiorly, and to the right, effectively expanding the distance between the heart and the breast/chest wall. As a result, the distance between the medial treatment field border and heart/lung is increased. Also, in a majority of DIBHmore » patients, the air drawn into the thoracic cavity increases the total lung volume. The DIBH was discussed by an AAPM Task Group 10 years ago in the AAPM TG 76 report. However, DIBH is still not the standard of care in many clinics, which may be partially due to challenges associated with its implementation. Therefore, this seccion will focus primarily on how to clinically implement four different DIBH techniques: (1) Active Breathing Control, (2) Spirometric Motion Management, (3) 3D Surface Image-Guided, and (4) Self-held Breath Control with Respiratory Monitoring and Feedback Guidance. Learning Objectives: Describe the physical displacement of the heart and the change in lung volume during DIBH and discuss dosimetric consequences of those changes. Provide an overview of the technical aspects. Describe work flow for patient simulation and treatment. Give an overview of commissioning and routine. Provide practical tips for clinical implementation.« less

WE-DE-209-04: 3D Surface Image-Guided

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tang, X.

Breast radiation therapy is associated with some risk of lung toxicity as well as cardiac toxicity for left-sided cases. Radiation doses to the lung and heart can be reduced by using the deep inspiration breath hold (DIBH) technique, in which the patient is simulated and treated during the deep inspiration phase of the breathing cycle. During DIBH, the heart is usually displaced posteriorly, inferiorly, and to the right, effectively expanding the distance between the heart and the breast/chest wall. As a result, the distance between the medial treatment field border and heart/lung is increased. Also, in a majority of DIBHmore » patients, the air drawn into the thoracic cavity increases the total lung volume. The DIBH was discussed by an AAPM Task Group 10 years ago in the AAPM TG 76 report. However, DIBH is still not the standard of care in many clinics, which may be partially due to challenges associated with its implementation. Therefore, this seccion will focus primarily on how to clinically implement four different DIBH techniques: (1) Active Breathing Control, (2) Spirometric Motion Management, (3) 3D Surface Image-Guided, and (4) Self-held Breath Control with Respiratory Monitoring and Feedback Guidance. Learning Objectives: Describe the physical displacement of the heart and the change in lung volume during DIBH and discuss dosimetric consequences of those changes. Provide an overview of the technical aspects. Describe work flow for patient simulation and treatment. Give an overview of commissioning and routine. Provide practical tips for clinical implementation.« less

WE-DE-209-00: Practical Implementation of Deep Inspiration Breath Hold Techniques for Breast Radiation Therapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

Breast radiation therapy is associated with some risk of lung toxicity as well as cardiac toxicity for left-sided cases. Radiation doses to the lung and heart can be reduced by using the deep inspiration breath hold (DIBH) technique, in which the patient is simulated and treated during the deep inspiration phase of the breathing cycle. During DIBH, the heart is usually displaced posteriorly, inferiorly, and to the right, effectively expanding the distance between the heart and the breast/chest wall. As a result, the distance between the medial treatment field border and heart/lung is increased. Also, in a majority of DIBHmore » patients, the air drawn into the thoracic cavity increases the total lung volume. The DIBH was discussed by an AAPM Task Group 10 years ago in the AAPM TG 76 report. However, DIBH is still not the standard of care in many clinics, which may be partially due to challenges associated with its implementation. Therefore, this seccion will focus primarily on how to clinically implement four different DIBH techniques: (1) Active Breathing Control, (2) Spirometric Motion Management, (3) 3D Surface Image-Guided, and (4) Self-held Breath Control with Respiratory Monitoring and Feedback Guidance. Learning Objectives: Describe the physical displacement of the heart and the change in lung volume during DIBH and discuss dosimetric consequences of those changes. Provide an overview of the technical aspects. Describe work flow for patient simulation and treatment. Give an overview of commissioning and routine. Provide practical tips for clinical implementation.« less

Monte Carlo calculated TG-60 dosimetry parameters for the {beta}{sup -} emitter {sup 153}Sm brachytherapy source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sadeghi, Mahdi; Taghdiri, Fatemeh; Hamed Hosseini, S.

Purpose: The formalism recommended by Task Group 60 (TG-60) of the American Association of Physicists in Medicine (AAPM) is applicable for {beta} sources. Radioactive biocompatible and biodegradable {sup 153}Sm glass seed without encapsulation is a {beta}{sup -} emitter radionuclide with a short half-life and delivers a high dose rate to the tumor in the millimeter range. This study presents the results of Monte Carlo calculations of the dosimetric parameters for the {sup 153}Sm brachytherapy source. Methods: Version 5 of the (MCNP) Monte Carlo radiation transport code was used to calculate two-dimensional dose distributions around the source. The dosimetric parameters ofmore » AAPM TG-60 recommendations including the reference dose rate, the radial dose function, the anisotropy function, and the one-dimensional anisotropy function were obtained. Results: The dose rate value at the reference point was estimated to be 9.21{+-}0.6 cGy h{sup -1} {mu}Ci{sup -1}. Due to the low energy beta emitted from {sup 153}Sm sources, the dose fall-off profile is sharper than the other beta emitter sources. The calculated dosimetric parameters in this study are compared to several beta and photon emitting seeds. Conclusions: The results show the advantage of the {sup 153}Sm source in comparison with the other sources because of the rapid dose fall-off of beta ray and high dose rate at the short distances of the seed. The results would be helpful in the development of the radioactive implants using {sup 153}Sm seeds for the brachytherapy treatment.« less

New head equivalent phantom for task and image performance evaluation representative for neurovascular procedures occurring in the Circle of Willis

NASA Astrophysics Data System (ADS)

Ionita, Ciprian N.; Loughran, Brendan; Jain, Amit; Swetadri Vasan, S. N.; Bednarek, Daniel R.; Levy, Elad; Siddiqui, Adnan H.; Snyder, Kenneth V.; Hopkins, L. N.; Rudin, Stephen

2012-03-01

Phantom equivalents of different human anatomical parts are routinely used for imaging system evaluation or dose calculations. The various recommendations on the generic phantom structure given by organizations such as the AAPM, are not always accurate when evaluating a very specific task. When we compared the AAPM head phantom containing 3 mm of aluminum to actual neuro-endovascular image guided interventions (neuro-EIGI) occurring in the Circle of Willis, we found that the system automatic exposure rate control (AERC) significantly underestimated the x-ray parameter selection. To build a more accurate phantom for neuro-EIGI, we reevaluated the amount of aluminum which must be included in the phantom. Human skulls were imaged at different angles, using various angiographic exposures, at kV's relevant to neuro-angiography. An aluminum step wedge was also imaged under identical conditions, and a correlation between the gray values of the imaged skulls and those of the aluminum step thicknesses was established. The average equivalent aluminum thickness for the skull samples for frontal projections in the Circle of Willis region was found to be about 13 mm. The results showed no significant changes in the average equivalent aluminum thickness with kV or mAs variation. When a uniform phantom using 13 mm aluminum and 15 cm acrylic was compared with an anthropomorphic head phantom the x-ray parameters selected by the AERC system were practically identical. These new findings indicate that for this specific task, the amount of aluminum included in the head equivalent must be increased substantially from 3 mm to a value of 13 mm.

MO-D-BRD-03: Radiobiology and Commissioning of Electronic Brachytherapy for IORT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, J.

2015-06-15

Electronic brachytherapy (eBT) has seen an insurgence of manufacturers entering the US market for use in radiation therapy. In addition to the established interstitial, intraluminary, and intracavitary applications of eBT, many centers are now using eBT to treat skin lesions. It is important for medical physicists working with electronic brachytherapy sources to understand the basic physics principles of the sources themselves as well as the variety of applications for which they are being used. The calibration of the sources is different from vendor to vendor and the traceability of calibrations has evolved as new sources came to market. In 2014,more » a new air-kerma based standard was introduced by the National Institute of Standards and Technology (NIST) to measure the output of an eBT source. Eventually commercial treatment planning systems should accommodate this new standard and provide NIST traceability to the end user. The calibration and commissioning of an eBT system is unique to its application and typically entails a list of procedural recommendations by the manufacturer. Commissioning measurements are performed using a variety of methods, some of which are modifications of existing AAPM Task Group protocols. A medical physicist should be familiar with the different AAPM Task Group recommendations for applicability to eBT and how to properly adapt them to their needs. In addition to the physical characteristics of an eBT source, the photon energy is substantially lower than from HDR Ir-192 sources. Consequently, tissue-specific dosimetry and radiobiological considerations are necessary when comparing these brachytherapy modalities and when making clinical decisions as a radiation therapy team. In this session, the physical characteristics and calibration methodologies of eBt sources will be presented as well as radiobiology considerations and other important clinical considerations. Learning Objectives: To understand the basic principles of electronic brachytherapy and the various applications for which it is being used. To understand the physics of the calibration and commissioning for electronic brachytherapy sources To understand the unique radiobiology and clinical implementation of electronic brachytherapy systems for skin and IORT techniques Xoft, Inc. contributed funding toward development of the NIST electronic brachytherapy facility (Michael Mitch).The University of Wisconsin (Wesley Culberson) has received research support funding from Xoft, Inc. Zoubir Ouhib has received partial funding from Elekta Esteya.« less

MO-D-BRD-01: Clinical Implementation of An Electronic Brachytherapy Program for the Skin

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ouhib, Z.

2015-06-15

Electronic brachytherapy (eBT) has seen an insurgence of manufacturers entering the US market for use in radiation therapy. In addition to the established interstitial, intraluminary, and intracavitary applications of eBT, many centers are now using eBT to treat skin lesions. It is important for medical physicists working with electronic brachytherapy sources to understand the basic physics principles of the sources themselves as well as the variety of applications for which they are being used. The calibration of the sources is different from vendor to vendor and the traceability of calibrations has evolved as new sources came to market. In 2014,more » a new air-kerma based standard was introduced by the National Institute of Standards and Technology (NIST) to measure the output of an eBT source. Eventually commercial treatment planning systems should accommodate this new standard and provide NIST traceability to the end user. The calibration and commissioning of an eBT system is unique to its application and typically entails a list of procedural recommendations by the manufacturer. Commissioning measurements are performed using a variety of methods, some of which are modifications of existing AAPM Task Group protocols. A medical physicist should be familiar with the different AAPM Task Group recommendations for applicability to eBT and how to properly adapt them to their needs. In addition to the physical characteristics of an eBT source, the photon energy is substantially lower than from HDR Ir-192 sources. Consequently, tissue-specific dosimetry and radiobiological considerations are necessary when comparing these brachytherapy modalities and when making clinical decisions as a radiation therapy team. In this session, the physical characteristics and calibration methodologies of eBt sources will be presented as well as radiobiology considerations and other important clinical considerations. Learning Objectives: To understand the basic principles of electronic brachytherapy and the various applications for which it is being used. To understand the physics of the calibration and commissioning for electronic brachytherapy sources To understand the unique radiobiology and clinical implementation of electronic brachytherapy systems for skin and IORT techniques Xoft, Inc. contributed funding toward development of the NIST electronic brachytherapy facility (Michael Mitch).The University of Wisconsin (Wesley Culberson) has received research support funding from Xoft, Inc. Zoubir Ouhib has received partial funding from Elekta Esteya.« less

MO-D-BRD-04: NIST Air-Kerma Standard for Electronic Brachytherapy Calibrations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mitch, M.

Electronic brachytherapy (eBT) has seen an insurgence of manufacturers entering the US market for use in radiation therapy. In addition to the established interstitial, intraluminary, and intracavitary applications of eBT, many centers are now using eBT to treat skin lesions. It is important for medical physicists working with electronic brachytherapy sources to understand the basic physics principles of the sources themselves as well as the variety of applications for which they are being used. The calibration of the sources is different from vendor to vendor and the traceability of calibrations has evolved as new sources came to market. In 2014,more » a new air-kerma based standard was introduced by the National Institute of Standards and Technology (NIST) to measure the output of an eBT source. Eventually commercial treatment planning systems should accommodate this new standard and provide NIST traceability to the end user. The calibration and commissioning of an eBT system is unique to its application and typically entails a list of procedural recommendations by the manufacturer. Commissioning measurements are performed using a variety of methods, some of which are modifications of existing AAPM Task Group protocols. A medical physicist should be familiar with the different AAPM Task Group recommendations for applicability to eBT and how to properly adapt them to their needs. In addition to the physical characteristics of an eBT source, the photon energy is substantially lower than from HDR Ir-192 sources. Consequently, tissue-specific dosimetry and radiobiological considerations are necessary when comparing these brachytherapy modalities and when making clinical decisions as a radiation therapy team. In this session, the physical characteristics and calibration methodologies of eBt sources will be presented as well as radiobiology considerations and other important clinical considerations. Learning Objectives: To understand the basic principles of electronic brachytherapy and the various applications for which it is being used. To understand the physics of the calibration and commissioning for electronic brachytherapy sources To understand the unique radiobiology and clinical implementation of electronic brachytherapy systems for skin and IORT techniques Xoft, Inc. contributed funding toward development of the NIST electronic brachytherapy facility (Michael Mitch).The University of Wisconsin (Wesley Culberson) has received research support funding from Xoft, Inc. Zoubir Ouhib has received partial funding from Elekta Esteya.« less

MO-D-BRD-00: Electronic Brachytherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

Electronic brachytherapy (eBT) has seen an insurgence of manufacturers entering the US market for use in radiation therapy. In addition to the established interstitial, intraluminary, and intracavitary applications of eBT, many centers are now using eBT to treat skin lesions. It is important for medical physicists working with electronic brachytherapy sources to understand the basic physics principles of the sources themselves as well as the variety of applications for which they are being used. The calibration of the sources is different from vendor to vendor and the traceability of calibrations has evolved as new sources came to market. In 2014,more » a new air-kerma based standard was introduced by the National Institute of Standards and Technology (NIST) to measure the output of an eBT source. Eventually commercial treatment planning systems should accommodate this new standard and provide NIST traceability to the end user. The calibration and commissioning of an eBT system is unique to its application and typically entails a list of procedural recommendations by the manufacturer. Commissioning measurements are performed using a variety of methods, some of which are modifications of existing AAPM Task Group protocols. A medical physicist should be familiar with the different AAPM Task Group recommendations for applicability to eBT and how to properly adapt them to their needs. In addition to the physical characteristics of an eBT source, the photon energy is substantially lower than from HDR Ir-192 sources. Consequently, tissue-specific dosimetry and radiobiological considerations are necessary when comparing these brachytherapy modalities and when making clinical decisions as a radiation therapy team. In this session, the physical characteristics and calibration methodologies of eBt sources will be presented as well as radiobiology considerations and other important clinical considerations. Learning Objectives: To understand the basic principles of electronic brachytherapy and the various applications for which it is being used. To understand the physics of the calibration and commissioning for electronic brachytherapy sources To understand the unique radiobiology and clinical implementation of electronic brachytherapy systems for skin and IORT techniques Xoft, Inc. contributed funding toward development of the NIST electronic brachytherapy facility (Michael Mitch).The University of Wisconsin (Wesley Culberson) has received research support funding from Xoft, Inc. Zoubir Ouhib has received partial funding from Elekta Esteya.« less

MO-D-BRD-02: Radiological Physics and Surface Lesion Treatments with Electronic Brachytherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fulkerson, R.

Electronic brachytherapy (eBT) has seen an insurgence of manufacturers entering the US market for use in radiation therapy. In addition to the established interstitial, intraluminary, and intracavitary applications of eBT, many centers are now using eBT to treat skin lesions. It is important for medical physicists working with electronic brachytherapy sources to understand the basic physics principles of the sources themselves as well as the variety of applications for which they are being used. The calibration of the sources is different from vendor to vendor and the traceability of calibrations has evolved as new sources came to market. In 2014,more » a new air-kerma based standard was introduced by the National Institute of Standards and Technology (NIST) to measure the output of an eBT source. Eventually commercial treatment planning systems should accommodate this new standard and provide NIST traceability to the end user. The calibration and commissioning of an eBT system is unique to its application and typically entails a list of procedural recommendations by the manufacturer. Commissioning measurements are performed using a variety of methods, some of which are modifications of existing AAPM Task Group protocols. A medical physicist should be familiar with the different AAPM Task Group recommendations for applicability to eBT and how to properly adapt them to their needs. In addition to the physical characteristics of an eBT source, the photon energy is substantially lower than from HDR Ir-192 sources. Consequently, tissue-specific dosimetry and radiobiological considerations are necessary when comparing these brachytherapy modalities and when making clinical decisions as a radiation therapy team. In this session, the physical characteristics and calibration methodologies of eBt sources will be presented as well as radiobiology considerations and other important clinical considerations. Learning Objectives: To understand the basic principles of electronic brachytherapy and the various applications for which it is being used. To understand the physics of the calibration and commissioning for electronic brachytherapy sources To understand the unique radiobiology and clinical implementation of electronic brachytherapy systems for skin and IORT techniques Xoft, Inc. contributed funding toward development of the NIST electronic brachytherapy facility (Michael Mitch).The University of Wisconsin (Wesley Culberson) has received research support funding from Xoft, Inc. Zoubir Ouhib has received partial funding from Elekta Esteya.« less

SU-E-T-649: Quality Assurances for Proton Therapy Delivery Equipment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Arjomandy, B; Kase, Y; Flanz, J

2015-06-15

Purpose: The number of proton therapy centers has increased dramatically over the past decade. Currently, there is no comprehensive set of guidelines that addresses quality assurance (QA) procedures for the different technologies used for proton therapy. The AAPM has charged task group 224 (TG-224) to provide recommendations for QA required for accurate and safe dose delivery, using existing and next generation proton therapy delivery equipment. Methods: A database comprised of QA procedures and tolerance limits was generated from many existing proton therapy centers in and outside of the US. These consist of proton therapy centers that possessed double scattering, uniformmore » scanning, and pencil beams delivery systems. The diversity in beam delivery systems as well as the existing devices to perform QA checks for different beam parameters is the main subject of TG-224. Based on current practice at the clinically active proton centers participating in this task group, consensus QA recommendations were developed. The methodologies and requirements of the parameters that must be verified for consistency of the performance of the proton beam delivery systems are discussed. Results: TG-224 provides procedures and QA checks for mechanical, imaging, safety and dosimetry requirements for different proton equipment. These procedures are categorized based on their importance and their required frequencies in order to deliver a safe and consistent dose. The task group provides daily, weekly, monthly, and annual QA check procedures with their tolerance limits. Conclusions: The procedures outlined in this protocol provide sufficient information to qualified medical physicists to perform QA checks for any proton delivery system. Execution of these procedures should provide confidence that proton therapy equipment is functioning as commissioned for patient treatment and delivers dose safely and accurately within the established tolerance limits. The report will be published in late 2015.« less

A dosimetric uncertainty analysis for photon-emitting brachytherapy sources: Report of AAPM Task Group No. 138 and GEC-ESTRO

DOE Office of Scientific and Technical Information (OSTI.GOV)

DeWerd, Larry A.; Ibbott, Geoffrey S.; Meigooni, Ali S.

2011-02-15

This report addresses uncertainties pertaining to brachytherapy single-source dosimetry preceding clinical use. The International Organization for Standardization (ISO) Guide to the Expression of Uncertainty in Measurement (GUM) and the National Institute of Standards and Technology (NIST) Technical Note 1297 are taken as reference standards for uncertainty formalism. Uncertainties in using detectors to measure or utilizing Monte Carlo methods to estimate brachytherapy dose distributions are provided with discussion of the components intrinsic to the overall dosimetric assessment. Uncertainties provided are based on published observations and cited when available. The uncertainty propagation from the primary calibration standard through transfer to the clinicmore » for air-kerma strength is covered first. Uncertainties in each of the brachytherapy dosimetry parameters of the TG-43 formalism are then explored, ending with transfer to the clinic and recommended approaches. Dosimetric uncertainties during treatment delivery are considered briefly but are not included in the detailed analysis. For low- and high-energy brachytherapy sources of low dose rate and high dose rate, a combined dosimetric uncertainty <5% (k=1) is estimated, which is consistent with prior literature estimates. Recommendations are provided for clinical medical physicists, dosimetry investigators, and source and treatment planning system manufacturers. These recommendations include the use of the GUM and NIST reports, a requirement of constancy of manufacturer source design, dosimetry investigator guidelines, provision of the lowest uncertainty for patient treatment dosimetry, and the establishment of an action level based on dosimetric uncertainty. These recommendations reflect the guidance of the American Association of Physicists in Medicine (AAPM) and the Groupe Europeen de Curietherapie-European Society for Therapeutic Radiology and Oncology (GEC-ESTRO) for their members and may also be used as guidance to manufacturers and regulatory agencies in developing good manufacturing practices for sources used in routine clinical treatments.« less

Tolerance limits and methodologies for IMRT measurement-based verification QA: Recommendations of AAPM Task Group No. 218.

PubMed

Miften, Moyed; Olch, Arthur; Mihailidis, Dimitris; Moran, Jean; Pawlicki, Todd; Molineu, Andrea; Li, Harold; Wijesooriya, Krishni; Shi, Jie; Xia, Ping; Papanikolaou, Nikos; Low, Daniel A

2018-04-01

Patient-specific IMRT QA measurements are important components of processes designed to identify discrepancies between calculated and delivered radiation doses. Discrepancy tolerance limits are neither well defined nor consistently applied across centers. The AAPM TG-218 report provides a comprehensive review aimed at improving the understanding and consistency of these processes as well as recommendations for methodologies and tolerance limits in patient-specific IMRT QA. The performance of the dose difference/distance-to-agreement (DTA) and γ dose distribution comparison metrics are investigated. Measurement methods are reviewed and followed by a discussion of the pros and cons of each. Methodologies for absolute dose verification are discussed and new IMRT QA verification tools are presented. Literature on the expected or achievable agreement between measurements and calculations for different types of planning and delivery systems are reviewed and analyzed. Tests of vendor implementations of the γ verification algorithm employing benchmark cases are presented. Operational shortcomings that can reduce the γ tool accuracy and subsequent effectiveness for IMRT QA are described. Practical considerations including spatial resolution, normalization, dose threshold, and data interpretation are discussed. Published data on IMRT QA and the clinical experience of the group members are used to develop guidelines and recommendations on tolerance and action limits for IMRT QA. Steps to check failed IMRT QA plans are outlined. Recommendations on delivery methods, data interpretation, dose normalization, the use of γ analysis routines and choice of tolerance limits for IMRT QA are made with focus on detecting differences between calculated and measured doses via the use of robust analysis methods and an in-depth understanding of IMRT verification metrics. The recommendations are intended to improve the IMRT QA process and establish consistent, and comparable IMRT QA criteria among institutions. © 2018 American Association of Physicists in Medicine.

The effect of time in use on the display performance of the iPad.

PubMed

Caffery, Liam J; Manthey, Kenneth L; Sim, Lawrence H

2016-07-01

The aim of this study was to evaluate changes to the luminance, luminance uniformity and conformance to the digital imaging and communication in medicine greyscale standard display function (GSDF) as a function of time in use for the iPad. Luminance measurements of the American Association of Physicists in Medicine (AAPM) Group 18 task group (TG18) luminance uniformity and luminance test patterns (TG18-UNL and TG18-LN8) were performed using a calibrated near-range luminance meter. Nine sets of measurements were taken, where the time in use of the iPad ranged from 0 to 2500 h. The maximum luminance (Lmax) of the display decreased (367-338 cdm(-2)) as a function of time. The minimum luminance remained constant. The maximum non-uniformity coefficient was 11%. Luminance uniformity decreased slightly as a function of time in use. The conformance of the iPad deviated from the GSDF curve at commencement of use. Deviation did not increase as a function of time in use. This study has demonstrated that the iPad display exhibits luminance degradation typical of liquid crystal displays. The Lmax of the iPad fell below the American College of Radiology-AAPM-Society of Imaging Informatics in Medicine recommendations for primary displays (>350 cdm(-2)) at approximately 1000 h in use. The Lmax recommendation for secondary displays (>250 cdm(-2)) was exceeded during the entire study. The maximum non-uniformity coefficient did not exceed the recommendations for either primary or secondary displays. The deviation from the GSDF exceeded the recommendations of the TG18 for use as either a primary or secondary display. The brightness, uniformity and contrast response are reasonably stable over the useful lifetime of the device; however, the device fails to meet the contrast response standard for either a primary or secondary display.

A dosimetric uncertainty analysis for photon-emitting brachytherapy sources: Report of AAPM Task Group No. 138 and GEC-ESTRO

PubMed Central

DeWerd, Larry A.; Ibbott, Geoffrey S.; Meigooni, Ali S.; Mitch, Michael G.; Rivard, Mark J.; Stump, Kurt E.; Thomadsen, Bruce R.; Venselaar, Jack L. M.

2011-01-01

This report addresses uncertainties pertaining to brachytherapy single-source dosimetry preceding clinical use. The International Organization for Standardization (ISO) Guide to the Expression of Uncertainty in Measurement (GUM) and the National Institute of Standards and Technology (NIST) Technical Note 1297 are taken as reference standards for uncertainty formalism. Uncertainties in using detectors to measure or utilizing Monte Carlo methods to estimate brachytherapy dose distributions are provided with discussion of the components intrinsic to the overall dosimetric assessment. Uncertainties provided are based on published observations and cited when available. The uncertainty propagation from the primary calibration standard through transfer to the clinic for air-kerma strength is covered first. Uncertainties in each of the brachytherapy dosimetry parameters of the TG-43 formalism are then explored, ending with transfer to the clinic and recommended approaches. Dosimetric uncertainties during treatment delivery are considered briefly but are not included in the detailed analysis. For low- and high-energy brachytherapy sources of low dose rate and high dose rate, a combined dosimetric uncertainty <5% (k=1) is estimated, which is consistent with prior literature estimates. Recommendations are provided for clinical medical physicists, dosimetry investigators, and source and treatment planning system manufacturers. These recommendations include the use of the GUM and NIST reports, a requirement of constancy of manufacturer source design, dosimetry investigator guidelines, provision of the lowest uncertainty for patient treatment dosimetry, and the establishment of an action level based on dosimetric uncertainty. These recommendations reflect the guidance of the American Association of Physicists in Medicine (AAPM) and the Groupe Européen de Curiethérapie–European Society for Therapeutic Radiology and Oncology (GEC-ESTRO) for their members and may also be used as guidance to manufacturers and regulatory agencies in developing good manufacturing practices for sources used in routine clinical treatments. PMID:21452716

A dosimetric uncertainty analysis for photon-emitting brachytherapy sources: report of AAPM Task Group No. 138 and GEC-ESTRO.

PubMed

DeWerd, Larry A; Ibbott, Geoffrey S; Meigooni, Ali S; Mitch, Michael G; Rivard, Mark J; Stump, Kurt E; Thomadsen, Bruce R; Venselaar, Jack L M

2011-02-01

This report addresses uncertainties pertaining to brachytherapy single-source dosimetry preceding clinical use. The International Organization for Standardization (ISO) Guide to the Expression of Uncertainty in Measurement (GUM) and the National Institute of Standards and Technology (NIST) Technical Note 1297 are taken as reference standards for uncertainty formalism. Uncertainties in using detectors to measure or utilizing Monte Carlo methods to estimate brachytherapy dose distributions are provided with discussion of the components intrinsic to the overall dosimetric assessment. Uncertainties provided are based on published observations and cited when available. The uncertainty propagation from the primary calibration standard through transfer to the clinic for air-kerma strength is covered first. Uncertainties in each of the brachytherapy dosimetry parameters of the TG-43 formalism are then explored, ending with transfer to the clinic and recommended approaches. Dosimetric uncertainties during treatment delivery are considered briefly but are not included in the detailed analysis. For low- and high-energy brachytherapy sources of low dose rate and high dose rate, a combined dosimetric uncertainty <5% (k=1) is estimated, which is consistent with prior literature estimates. Recommendations are provided for clinical medical physicists, dosimetry investigators, and source and treatment planning system manufacturers. These recommendations include the use of the GUM and NIST reports, a requirement of constancy of manufacturer source design, dosimetry investigator guidelines, provision of the lowest uncertainty for patient treatment dosimetry, and the establishment of an action level based on dosimetric uncertainty. These recommendations reflect the guidance of the American Association of Physicists in Medicine (AAPM) and the Groupe Européen de Curiethérapie-European Society for Therapeutic Radiology and Oncology (GEC-ESTRO) for their members and may also be used as guidance to manufacturers and regulatory agencies in developing good manufacturing practices for sources used in routine clinical treatments.

AAPM-RSS Medical Physics Practice Guideline 9.a. for SRS-SBRT.

PubMed

Halvorsen, Per H; Cirino, Eileen; Das, Indra J; Garrett, Jeffrey A; Yang, Jun; Yin, Fang-Fang; Fairobent, Lynne A

2017-09-01

The American Association of Physicists in Medicine (AAPM) is a nonprofit professional society whose primary purposes are to advance the science, education, and professional practice of medical physics. The AAPM has more than 8,000 members and is the principal organization of medical physicists in the United States. The AAPM will periodically define new practice guidelines for medical physics practice to help advance the science of medical physics and to improve the quality of service to patients throughout the United States. Existing medical physics practice guidelines will be reviewed for revision or renewal, as appropriate, on their fifth anniversary or sooner. Each medical physics practice guideline represents a policy statement by the AAPM, has undergone a thorough consensus process in which it has been subjected to extensive review, and requires the approval of the Professional Council. The medical physics practice guidelines recognize that the safe and effective use of diagnostic and therapeutic radiology requires specific training, skills, and techniques, as described in each document. Reproduction or modification of the published practice guidelines and technical standards by those entities not providing these services is not authorized. The following terms are used in the AAPM practice guidelines: Must and Must Not: Used to indicate that adherence to the recommendation is considered necessary to conform to this practice guideline. Should and Should Not: Used to indicate a prudent practice to which exceptions may occasionally be made in appropriate circumstances. Approved by AAPM Professional Council 3-31-2017 and Executive Committee 4-4-2017. © 2017 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of Physicists in Medicine.

TH-EF-204-00: AAPM-AMPR (Russia)-SEFM (Spain) Joint Course On Challenges and Advantages of Small Field Radiation Treatment Techniques

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

Joanna E. Cygler, Jan Seuntjens, J. Daniel Bourland, M. Saiful Huq, Josep Puxeu Vaque, Daniel Zucca Aparicio, Tatiana Krylova, Yuri Kirpichev, Eric Ford, Caridad Borras Stereotactic Radiation Therapy (SRT) utilizes small static and dynamic (IMRT) fields, to successfully treat malignant and benign diseases using techniques such as Stereotactic Radiosurgery (SRS) and Stereotactic Body Radiation Therapy (SBRT). SRT is characterized by sharp dose gradients for individual fields and their resultant dose distributions. For appropriate targets, small field radiotherapy offers improved treatment quality by allowing better sparing of organs at risk while delivering the prescribed target dose. Specialized small field treatment deliverymore » systems, such as robotic-controlled linear accelerators, gamma radiosurgery units, and dynamic arc linear accelerators may utilize rigid fixation, image guidance, and tumor tracking, to insure precise dose delivery to static or moving targets. However, in addition to great advantages, small field delivery techniques present special technical challenges for dose calibration due to unique geometries and small field sizes not covered by existing reference dosimetry protocols such as AAPM TG-51 or IAEA TRS 398. In recent years extensive research has been performed to understand small field dosimetry and measurement instrumentation. AAPM, IAEA and ICRU task groups are expected to provide soon recommendations on the dosimetry of small radiation fields. In this symposium we will: 1] discuss the physics, instrumentation, methodologies and challenges for small field radiation dose measurements; 2] review IAEA and ICRU recommendations on prescribing, recording and reporting of small field radiation therapy; 3] discuss selected clinical applications and technical aspects for specialized image-guided, small field, linear accelerator based treatment techniques such as IMRT and SBRT. Learning Objectives: To learn the physics of small fields in contrast to dosimetry of conventional fields To learn about detectors suitable for small fields To learn about the role of Monte Carlo simulations in determination of small field output factors To provide an overview of the IAEA small field dosimetry recommendations To provide an overview of the content of the ICRU report on Prescribing, Reporting and Recording of Small Field Radiation Therapy. To learn about special technical considerations in delivering IMRT and SBRT treatments To appreciate specific challenges of IMRT implementation J. Seuntjens, Natural Sciences and Engineering Research Council; Canadian Institutes of Health Research.« less

AAPM Medical Physics Practice Guideline 5.a.: Commissioning and QA of Treatment Planning Dose Calculations — Megavoltage Photon and Electron Beams

PubMed Central

Das, Indra J.; Feygelman, Vladimir; Fraass, Benedick A.; Kry, Stephen F.; Marshall, Ingrid R.; Mihailidis, Dimitris N.; Ouhib, Zoubir; Ritter, Timothy; Snyder, Michael G.; Fairobent, Lynne

2015-01-01

The American Association of Physicists in Medicine (AAPM) is a nonprofit professional society whose primary purposes are to advance the science, education and professional practice of medical physics. The AAPM has more than 8,000 members and is the principal organization of medical physicists in the United States. The AAPM will periodically define new practice guidelines for medical physics practice to help advance the science of medical physics and to improve the quality of service to patients throughout the United States. Existing medical physics practice guidelines will be reviewed for the purpose of revision or renewal, as appropriate, on their fifth anniversary or sooner. Each medical physics practice guideline represents a policy statement by the AAPM, has undergone a thorough consensus process in which it has been subjected to extensive review, and requires the approval of the Professional Council. The medical physics practice guidelines recognize that the safe and effective use of diagnostic and therapeutic radiology requires specific training, skills, and techniques, as described in each document. Reproduction or modification of the published practice guidelines and technical standards by those entities not providing these services is not authorized. The following terms are used in the AAPM practice guidelines: Must and Must Not: Used to indicate that adherence to the recommendation is considered necessary to conform to this practice guideline.Should and Should Not: Used to indicate a prudent practice to which exceptions may occasionally be made in appropriate circumstances. PMID:26699330

AAPM Medical Physics Practice Guideline 5.a.: Commissioning and QA of Treatment Planning Dose Calculations - Megavoltage Photon and Electron Beams.

PubMed

Smilowitz, Jennifer B; Das, Indra J; Feygelman, Vladimir; Fraass, Benedick A; Kry, Stephen F; Marshall, Ingrid R; Mihailidis, Dimitris N; Ouhib, Zoubir; Ritter, Timothy; Snyder, Michael G; Fairobent, Lynne

2015-09-08

The American Association of Physicists in Medicine (AAPM) is a nonprofit professional society whose primary purposes are to advance the science, education and professional practice of medical physics. The AAPM has more than 8,000 members and is the principal organization of medical physicists in the United States. The AAPM will periodically define new practice guidelines for medical physics practice to help advance the science of medical physics and to improve the quality of service to patients throughout the United States. Existing medical physics practice guidelines will be reviewed for the purpose of revision or renewal, as appropriate, on their fifth anniversary or sooner. Each medical physics practice guideline represents a policy statement by the AAPM, has undergone a thorough consensus process in which it has been subjected to extensive review, and requires the approval of the Professional Council. The medical physics practice guidelines recognize that the safe and effective use of diagnostic and therapeutic radiology requires specific training, skills, and techniques, as described in each document. Reproduction or modification of the published practice guidelines and technical standards by those entities not providing these services is not authorized. The following terms are used in the AAPM practice guidelines:• Must and Must Not: Used to indicate that adherence to the recommendation is considered necessary to conform to this practice guideline.• Should and Should Not: Used to indicate a prudent practice to which exceptions may occasionally be made in appropriate circumstances.

AAPM Medical Physics Practice Guideline 3.a: Levels of supervision for medical physicists in clinical training.

PubMed

Seibert, J Anthony; Clements, Jessica B; Halvorsen, Per H; Herman, Michael G; Martin, Melissa C; Palta, Jatinder; Pfeiffer, Douglas E; Pizzutiello, Robert J; Schueler, Beth A; Shepard, S Jeff; Fairobrent, Lynne A

2015-05-08

The American Association of Physicists in Medicine (AAPM) is a nonprofit professional society whose primary purposes are to advance the science, education and professional practice of medical physics. The AAPM has more than 8,000 members and is the principal organization of medical physicists in the United States.The AAPM will periodically define new practice guidelines for medical physics practice to help advance the science of medical physics and to improve the quality of service to patients throughout the United States. Existing medical physics practice guidelines will be reviewed for the purpose of revision or renewal, as appropriate, on their fifth anniversary or sooner.Each medical physics practice guideline represents a policy statement by the AAPM, has undergone a thorough consensus process in which it has been subjected to extensive review, and requires the approval of the Professional Council. The medical physics practice guidelines recognize that the safe and effective use of diagnostic and therapeutic radiology requires specific training, skills, and techniques, as described in each document. Reproduction or modification of the published practice guidelines and technical standards by those entities not providing these services is not authorized.The following terms are used in the AAPM practice guidelines:Must and Must Not: Used to indicate that adherence to the recommendation is considered necessary to conform to this practice guideline.Should and Should Not: Used to indicate a prudent practice to which exceptions may occasionally be made in appropriate circumstances.

Dosimetric evaluation of IMRT plan for homogenous and inhomogeneous medium using AAPM TG-119 protocol

NASA Astrophysics Data System (ADS)

Fatimah, L. A. N.; Wibowo, W. E.; Pawiro, S. A.

2017-05-01

The American Association of Physicists in Medicine (AAPM) TG-119 protocol has been applied for dose verification in IMRT technique. However, some criteria in the protocol need to be verified for inhomogeneous medium and small volume targets. Hence, the purpose of this study was to verify the assessment criteria of dose verification in AAPM TG-119 for inhomogeneous medium and small volume targets. The work has been conducted by dose verification for homogeneous (phantom A) and inhomogeneous phantoms (phantom B and C) on two geometrical targets: C-shape and circular targets. The targets were simulated using 7 static dMLC IMRT fields at two different depths of 5 g/cm2 and 10 g/cm2. The dose optimisation and calculation were done by using Pinnacle3 for 6 MV photons beam. The planning objectives were set according to AAPM TG-119 parameters. The plan analysis was conducted by Conformity Index and Homogeneity Index. The point dose measurements were conducted with Exradin A16, Semiflex 0.125cc, and Gafchromic EBT3. The plan results show that CI for C-shape target is in the range of 0.710-0.999 at 10 g/cm2 depth and 0.691-1.613 at 5 g/cm2. In addition, HI for C-shape and circular were in the range of 6.3%-58.7% and 5.4%-87.1% for 10 g/cm2 depth. The measurement results show that the dose measurement at inhomogeneous medium and small volume targets are much lower than the criteria in AAPM TG-119. In conclusion, the criteria in the AAPM TG-119 cannot be fully implemented for inhomogeneous medium and small volume targets.

AAPM medical physics practice guideline 6.a.: Performance characteristics of radiation dose index monitoring systems.

PubMed

Gress, Dustin A; Dickinson, Renee L; Erwin, William D; Jordan, David W; Kobistek, Robert J; Stevens, Donna M; Supanich, Mark P; Wang, Jia; Fairobent, Lynne A

2017-07-01

The American Association of Physicists in Medicine (AAPM) is a nonprofit professional society whose primary purposes are to advance the science, education and professional practice of medical physics. The AAPM has more than 8,000 members and is the principal organization of medical physicists in the United States. The AAPM will periodically define new practice guidelines for medical physics practice to help advance the science of medical physics and to improve the quality of service to patients throughout the United States. Existing medical physics practice guidelines will be reviewed for the purpose of revision or renewal, as appropriate, on their fifth anniversary or sooner. Each medical physics practice guideline represents a policy statement by the AAPM, has undergone a thorough consensus process in which it has been subjected to extensive review, and requires the approval of the Professional Council. The medical physics practice guidelines recognize that the safe and effective use of diagnostic and therapeutic radiology requires specific training, skills, and techniques, as described in each document. Reproduction or modification of the published practice guidelines and technical standards by those entities not providing these services is not authorized. The following terms are used in the AAPM practice guidelines: •Must and Must Not: Used to indicate that adherence to the recommendation is considered necessary to conform to this practice guideline. •Should and Should Not: Used to indicate a prudent practice to which exceptions may occasionally be made in appropriate circumstances. © 2017 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of Physicists in Medicine.

Medical Physics Practice Guideline 4.a: Development, implementation, use and maintenance of safety checklists

PubMed Central

de los Santos, E. Fong; Evans, Suzanne; Ford, Eric C.; Gaiser, James E.; Hayden, Sandra E.; Huffman, Kristina E.; Johnson, Jennifer L.; Mechalakos, James G.; Stern, Robin L.; Terezakis, Stephanie; Thomadsen, Bruce R.; Pronovost, Peter J.; Fairobent, Lynne A.

2015-01-01

The American Association of Physicists in Medicine (AAPM) is a nonprofit professional society whose primary purposes are to advance the science, education and professional practice of medical physics. The AAPM has more than 8,000 members and is the principal organization of medical physicists in the United States. The AAPM will periodically define new practice guidelines for medical physics practice to help advance the science of medical physics and to improve the quality of service to patients throughout the United States. Existing medical physics practice guidelines will be reviewed for the purpose of revision or renewal, as appropriate, on their fifth anniversary or sooner. Each medical physics practice guideline represents a policy statement by the AAPM, has undergone a thorough consensus process in which it has been subjected to extensive review, and requires the approval of the Professional Council. The medical physics practice guidelines recognize that the safe and effective use of diagnostic and therapeutic radiology requires specific training, skills, and techniques, as described in each document. Reproduction or modification of the published practice guidelines and technical standards by those entities not providing these services is not authorized. The following terms are used in the AAPM practice guidelines: Must and Must Not: Used to indicate that adherence to the recommendation is considered necessary to conform to this practice guideline.Should and Should Not: Used to indicate a prudent practice to which exceptions may occasionally be made in appropriate circumstances. PMID:26103502

Medical Physics Practice Guideline 4.a: Development, implementation, use and maintenance of safety checklists.

PubMed

Fong de Los Santos, Luis E; Evans, Suzanne; Ford, Eric C; Gaiser, James E; Hayden, Sandra E; Huffman, Kristina E; Johnson, Jennifer L; Mechalakos, James G; Stern, Robin L; Terezakis, Stephanie; Thomadsen, Bruce R; Pronovost, Peter J; Fairobent, Lynne A

2015-05-08

The American Association of Physicists in Medicine (AAPM) is a nonprofit professional society whose primary purposes are to advance the science, education and professional practice of medical physics. The AAPM has more than 8,000 members and is the principal organization of medical physicists in the United States.The AAPM will periodically define new practice guidelines for medical physics practice to help advance the science of medical physics and to improve the quality of service to patients throughout the United States. Existing medical physics practice guidelines will be reviewed for the purpose of revision or renewal, as appropriate, on their fifth anniversary or sooner.Each medical physics practice guideline represents a policy statement by the AAPM, has undergone a thorough consensus process in which it has been subjected to extensive review, and requires the approval of the Professional Council. The medical physics practice guidelines recognize that the safe and effective use of diagnostic and therapeutic radiology requires specific training, skills, and techniques, as described in each document. Reproduction or modification of the published practice guidelines and technical standards by those entities not providing these services is not authorized.The following terms are used in the AAPM practice guidelines:Must and Must Not: Used to indicate that adherence to the recommendation is considered necessary to conform to this practice guideline.Should and Should Not: Used to indicate a prudent practice to which exceptions may occasionally be made in appropriate circumstances.

SU-E-CAMPUS-J-04: Image Guided Radiation Therapy (IGRT): Review of Technical Standards and Credentialing in Radiotherapy Clinical Trials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Giaddui, T; Chen, W; Yu, J

2014-06-15

Purpose: To review IGRT credentialing experience and unexpected technical issues encountered in connection with advanced radiotherapy technologies as implemented in RTOG clinical trials. To update IGRT credentialing procedures with the aim of improving the quality of the process, and to increase the proportion of IGRT credentialing compliance. To develop a living disease site-specific IGRT encyclopedia. Methods: Numerous technical issues were encountered during the IGRT credentialing process. The criteria used for credentialing review were based on: image quality; anatomy included in fused data sets and shift results. Credentialing requirements have been updated according to the AAPM task group reports for IGRTmore » to ensure that all required technical items are included in the quality review process. Implementation instructions have been updated and expanded for recent protocols. Results: Technical issues observed during the credentialing review process include, but are not limited to: poor quality images; inadequate image acquisition region; poor data quality; shifts larger than acceptable; no soft tissue surrogate. The updated IGRT credentialing process will address these issues and will also include the technical items required from AAPM: TG 104; TG 142 and TG 179 reports. An instruction manual has been developed describing a remote credentialing method for reviewers. Submission requirements are updated, including images/documents as well as facility questionnaire. The review report now includes summary of the review process and the parameters that reviewers check. We have reached consensus on the minimum IGRT technical requirement for a number of disease sites. RTOG 1311(NRG-BR002A Phase 1 Study of Stereotactic Body Radiotherapy (SBRT) for the Treatment of Multiple Metastases) is an example, here; the protocol specified the minimum requirement for each anatomical sites (with/without fiducials). Conclusion: Technical issues are identified and reported. IGRT guidelines are updated, with the corresponding credentialing requirements. An IGRT encyclopedia describing site-specific implementation issues is currently in development.« less

Comparison of Head Scatter Factor for 6MV and 10MV flattened (FB) and Unflattened (FFF) Photon Beam using indigenously Designed Columnar Mini Phantom.

PubMed

Ashokkumar, Sigamani; Nambi Raj, N Arunai; Sinha, Sujit Nath; Yadav, Girigesh; Thiyagarajan, Rajesh; Raman, Kothanda; Mishra, Manindra Bhushan

2014-07-01

To measure and compare the head scatter factor for flattened (FB) and unflattened (FFF) of 6MV and 10MV photon beam using indigenously designed mini phantom. A columnar mini phantom was designed as recommended by AAPM Task Group 74 with low and high atomic number materials at 10 cm (mini phantom) and at approximately twice the depth of maximum dose water equivalent thickness (brass build-up cap). Scatter in the accelerator (Sc) values of 6MV-FFF photon beams are lesser than that of the 6MV-FB photon beams (0.66-2.8%; Clinac iX, 2300CD) and (0.47-1.74%; True beam) for field sizes ranging from 10 × 10 cm(2) to 40 × 40 cm(2). Sc values of 10MV-FFF photon beams are lesser (0.61-2.19%; True beam) than that of the 10MV-FB photons beams for field sizes ranging from 10 × 10 cm(2) to 40 × 40 cm(2). The SSD had no influence on head scatter for both flattened and unflattened beams and irrespective of head design of the different linear accelerators. The presence of field shaping device influences the Sc values. The collimator exchange effect reveals that the opening of the upper jaw increases Sc irrespective of FB or FFF photon beams and different linear accelerators, and it is less significant in FFF beams. Sc values of 6MV-FB square field were in good agreement with that of AAPM, TG-74 published data for Varian (Clinac iX, 2300CD) accelerator. Our results confirm that the removal of flattening filter decreases in the head scatter factor compared to flattened beam. This could reduce the out-of-field dose in advanced treatment delivery techniques.

Comparison of Head Scatter Factor for 6MV and 10MV flattened (FB) and Unflattened (FFF) Photon Beam using indigenously Designed Columnar Mini Phantom

PubMed Central

Ashokkumar, Sigamani; Nambi Raj, N Arunai; Sinha, Sujit Nath; Yadav, Girigesh; Thiyagarajan, Rajesh; Raman, Kothanda; Mishra, Manindra Bhushan

2014-01-01

To measure and compare the head scatter factor for flattened (FB) and unflattened (FFF) of 6MV and 10MV photon beam using indigenously designed mini phantom. A columnar mini phantom was designed as recommended by AAPM Task Group 74 with low and high atomic number materials at 10 cm (mini phantom) and at approximately twice the depth of maximum dose water equivalent thickness (brass build-up cap). Scatter in the accelerator (Sc) values of 6MV-FFF photon beams are lesser than that of the 6MV-FB photon beams (0.66-2.8%; Clinac iX, 2300CD) and (0.47-1.74%; True beam) for field sizes ranging from 10 × 10 cm2 to 40 × 40 cm2. Sc values of 10MV-FFF photon beams are lesser (0.61-2.19%; True beam) than that of the 10MV-FB photons beams for field sizes ranging from 10 × 10 cm2 to 40 × 40 cm2. The SSD had no influence on head scatter for both flattened and unflattened beams and irrespective of head design of the different linear accelerators. The presence of field shaping device influences the Sc values. The collimator exchange effect reveals that the opening of the upper jaw increases Sc irrespective of FB or FFF photon beams and different linear accelerators, and it is less significant in FFF beams. Sc values of 6MV-FB square field were in good agreement with that of AAPM, TG-74 published data for Varian (Clinac iX, 2300CD) accelerator. Our results confirm that the removal of flattening filter decreases in the head scatter factor compared to flattened beam. This could reduce the out-of-field dose in advanced treatment delivery techniques. PMID:25190997

Process-based quality management for clinical implementation of adaptive radiotherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Noel, Camille E.; Santanam, Lakshmi; Parikh, Parag J.

Purpose: Intensity-modulated adaptive radiotherapy (ART) has been the focus of considerable research and developmental work due to its potential therapeutic benefits. However, in light of its unique quality assurance (QA) challenges, no one has described a robust framework for its clinical implementation. In fact, recent position papers by ASTRO and AAPM have firmly endorsed pretreatment patient-specific IMRT QA, which limits the feasibility of online ART. The authors aim to address these obstacles by applying failure mode and effects analysis (FMEA) to identify high-priority errors and appropriate risk-mitigation strategies for clinical implementation of intensity-modulated ART. Methods: An experienced team of twomore » clinical medical physicists, one clinical engineer, and one radiation oncologist was assembled to perform a standard FMEA for intensity-modulated ART. A set of 216 potential radiotherapy failures composed by the forthcoming AAPM task group 100 (TG-100) was used as the basis. Of the 216 failures, 127 were identified as most relevant to an ART scheme. Using the associated TG-100 FMEA values as a baseline, the team considered how the likeliness of occurrence (O), outcome severity (S), and likeliness of failure being undetected (D) would change for ART. New risk priority numbers (RPN) were calculated. Failures characterized by RPN ≥ 200 were identified as potentially critical. Results: FMEA revealed that ART RPN increased for 38% (n = 48/127) of potential failures, with 75% (n = 36/48) attributed to failures in the segmentation and treatment planning processes. Forty-three of 127 failures were identified as potentially critical. Risk-mitigation strategies include implementing a suite of quality control and decision support software, specialty QA software/hardware tools, and an increase in specially trained personnel. Conclusions: Results of the FMEA-based risk assessment demonstrate that intensity-modulated ART introduces different (but not necessarily more) risks than standard IMRT and may be safely implemented with the proper mitigations.« less

Reference Dosimetry according to the New German Protocol DIN 6800-2 and Comparison with IAEA TRS 398 and AAPM TG 51*

PubMed Central

Zakaria, A; Schuette, W; Younan, C

2011-01-01

The preceding DIN 6800-2 (1997) protocol has been revised by a German task group and its latest version was published in March 2008 as the national standard dosimetry protocol DIN 6800-2 (2008 March). Since then, in Germany the determination of absorbed dose to water for high-energy photon and electron beams has to be performed according to this new German dosimetry protocol. The IAEA Code of Practice TRS 398 (2000) and the AAPM TG-51 are the two main protocols applied internationally. The new German version has widely adapted the methodology and dosimetric data of TRS-398. This paper investigates systematically the DIN 6800-2 protocol and compares it with the procedures and results obtained by using the international protocols. The investigation was performed with 6 MV and 18 MV photon beams as well as with electron beams from 5 MeV to 21 MeV. While only cylindrical chambers were used for photon beams, the measurements of electron beams were performed by using cylindrical and plane-parallel chambers. It was found that the discrepancies in the determination of absorbed dose to water among the three protocols were 0.23% for photon beams and 1.2% for electron beams. The determination of water absorbed dose was also checked by a national audit procedure using TLDs. The comparison between the measurements following the DIN 6800-2 protocol and the TLD audit-procedure confirmed a difference of less than 2%. The advantage of the new German protocol DIN 6800-2 lies in the renouncement on the cross calibration procedure as well as its clear presentation of formulas and parameters. In the past, the different protocols evoluted differently from time to time. Fortunately today, a good convergence has been obtained in concepts and methods. PMID:22287987

Reference Dosimetry according to the New German Protocol DIN 6800-2 and Comparison with IAEA TRS 398 and AAPM TG 51.

PubMed

Zakaria, A; Schuette, W; Younan, C

2011-04-01

The preceding DIN 6800-2 (1997) protocol has been revised by a German task group and its latest version was published in March 2008 as the national standard dosimetry protocol DIN 6800-2 (2008 March). Since then, in Germany the determination of absorbed dose to water for high-energy photon and electron beams has to be performed according to this new German dosimetry protocol. The IAEA Code of Practice TRS 398 (2000) and the AAPM TG-51 are the two main protocols applied internationally. The new German version has widely adapted the methodology and dosimetric data of TRS-398. This paper investigates systematically the DIN 6800-2 protocol and compares it with the procedures and results obtained by using the international protocols. The investigation was performed with 6 MV and 18 MV photon beams as well as with electron beams from 5 MeV to 21 MeV. While only cylindrical chambers were used for photon beams, the measurements of electron beams were performed by using cylindrical and plane-parallel chambers. It was found that the discrepancies in the determination of absorbed dose to water among the three protocols were 0.23% for photon beams and 1.2% for electron beams. The determination of water absorbed dose was also checked by a national audit procedure using TLDs. The comparison between the measurements following the DIN 6800-2 protocol and the TLD audit-procedure confirmed a difference of less than 2%. The advantage of the new German protocol DIN 6800-2 lies in the renouncement on the cross calibration procedure as well as its clear presentation of formulas and parameters. In the past, the different protocols evoluted differently from time to time. Fortunately today, a good convergence has been obtained in concepts and methods.

Process-based quality management for clinical implementation of adaptive radiotherapy

PubMed Central

Noel, Camille E.; Santanam, Lakshmi; Parikh, Parag J.; Mutic, Sasa

2014-01-01

Purpose: Intensity-modulated adaptive radiotherapy (ART) has been the focus of considerable research and developmental work due to its potential therapeutic benefits. However, in light of its unique quality assurance (QA) challenges, no one has described a robust framework for its clinical implementation. In fact, recent position papers by ASTRO and AAPM have firmly endorsed pretreatment patient-specific IMRT QA, which limits the feasibility of online ART. The authors aim to address these obstacles by applying failure mode and effects analysis (FMEA) to identify high-priority errors and appropriate risk-mitigation strategies for clinical implementation of intensity-modulated ART. Methods: An experienced team of two clinical medical physicists, one clinical engineer, and one radiation oncologist was assembled to perform a standard FMEA for intensity-modulated ART. A set of 216 potential radiotherapy failures composed by the forthcoming AAPM task group 100 (TG-100) was used as the basis. Of the 216 failures, 127 were identified as most relevant to an ART scheme. Using the associated TG-100 FMEA values as a baseline, the team considered how the likeliness of occurrence (O), outcome severity (S), and likeliness of failure being undetected (D) would change for ART. New risk priority numbers (RPN) were calculated. Failures characterized by RPN ≥ 200 were identified as potentially critical. Results: FMEA revealed that ART RPN increased for 38% (n = 48/127) of potential failures, with 75% (n = 36/48) attributed to failures in the segmentation and treatment planning processes. Forty-three of 127 failures were identified as potentially critical. Risk-mitigation strategies include implementing a suite of quality control and decision support software, specialty QA software/hardware tools, and an increase in specially trained personnel. Conclusions: Results of the FMEA-based risk assessment demonstrate that intensity-modulated ART introduces different (but not necessarily more) risks than standard IMRT and may be safely implemented with the proper mitigations. PMID:25086527

A quantitative three-dimensional dose attenuation analysis around Fletcher-Suit-Delclos due to stainless steel tube for high-dose-rate brachytherapy by Monte Carlo calculations.

PubMed

Parsai, E Ishmael; Zhang, Zhengdong; Feldmeier, John J

2009-01-01

The commercially available brachytherapy treatment-planning systems today, usually neglects the attenuation effect from stainless steel (SS) tube when Fletcher-Suit-Delclos (FSD) is used in treatment of cervical and endometrial cancers. This could lead to potential inaccuracies in computing dwell times and dose distribution. A more accurate analysis quantifying the level of attenuation for high-dose-rate (HDR) iridium 192 radionuclide ((192)Ir) source is presented through Monte Carlo simulation verified by measurement. In this investigation a general Monte Carlo N-Particles (MCNP) transport code was used to construct a typical geometry of FSD through simulation and compare the doses delivered to point A in Manchester System with and without the SS tubing. A quantitative assessment of inaccuracies in delivered dose vs. the computed dose is presented. In addition, this investigation expanded to examine the attenuation-corrected radial and anisotropy dose functions in a form parallel to the updated AAPM Task Group No. 43 Report (AAPM TG-43) formalism. This will delineate quantitatively the inaccuracies in dose distributions in three-dimensional space. The changes in dose deposition and distribution caused by increased attenuation coefficient resulted from presence of SS are quantified using MCNP Monte Carlo simulations in coupled photon/electron transport. The source geometry was that of the Vari Source wire model VS2000. The FSD was that of the Varian medical system. In this model, the bending angles of tandem and colpostats are 15 degrees and 120 degrees , respectively. We assigned 10 dwell positions to the tandem and 4 dwell positions to right and left colpostats or ovoids to represent a typical treatment case. Typical dose delivered to point A was determined according to Manchester dosimetry system. Based on our computations, the reduction of dose to point A was shown to be at least 3%. So this effect presented by SS-FSD systems on patient dose is of concern.

Process-based quality management for clinical implementation of adaptive radiotherapy.

PubMed

Noel, Camille E; Santanam, Lakshmi; Parikh, Parag J; Mutic, Sasa

2014-08-01

Intensity-modulated adaptive radiotherapy (ART) has been the focus of considerable research and developmental work due to its potential therapeutic benefits. However, in light of its unique quality assurance (QA) challenges, no one has described a robust framework for its clinical implementation. In fact, recent position papers by ASTRO and AAPM have firmly endorsed pretreatment patient-specific IMRT QA, which limits the feasibility of online ART. The authors aim to address these obstacles by applying failure mode and effects analysis (FMEA) to identify high-priority errors and appropriate risk-mitigation strategies for clinical implementation of intensity-modulated ART. An experienced team of two clinical medical physicists, one clinical engineer, and one radiation oncologist was assembled to perform a standard FMEA for intensity-modulated ART. A set of 216 potential radiotherapy failures composed by the forthcoming AAPM task group 100 (TG-100) was used as the basis. Of the 216 failures, 127 were identified as most relevant to an ART scheme. Using the associated TG-100 FMEA values as a baseline, the team considered how the likeliness of occurrence (O), outcome severity (S), and likeliness of failure being undetected (D) would change for ART. New risk priority numbers (RPN) were calculated. Failures characterized by RPN ≥ 200 were identified as potentially critical. FMEA revealed that ART RPN increased for 38% (n = 48/127) of potential failures, with 75% (n = 36/48) attributed to failures in the segmentation and treatment planning processes. Forty-three of 127 failures were identified as potentially critical. Risk-mitigation strategies include implementing a suite of quality control and decision support software, specialty QA software/hardware tools, and an increase in specially trained personnel. Results of the FMEA-based risk assessment demonstrate that intensity-modulated ART introduces different (but not necessarily more) risks than standard IMRT and may be safely implemented with the proper mitigations.

Optimization of permanent breast seed implant dosimetry incorporating tissue heterogeneity

NASA Astrophysics Data System (ADS)

Mashouf, Shahram

Seed brachytherapy is currently used for adjuvant radiotherapy of early stage prostate and breast cancer patients. The current standard for calculation of dose around brachytherapy sources is based on the AAPM TG43 formalism, which generates the dose in homogeneous water medium. Recently, AAPM task group no. 186 (TG186) emphasized the importance of accounting for heterogeneities. In this work we introduce an analytical dose calculation algorithm in heterogeneous media using CT images. The advantages over other methods are computational efficiency and the ease of integration into clinical use. An Inhomogeneity Correction Factor (ICF) is introduced as the ratio of absorbed dose in tissue to that in water medium. ICF is a function of tissue properties and independent of the source structure. The ICF is extracted using CT images and the absorbed dose in tissue can then be calculated by multiplying the dose as calculated by the TG43 formalism times ICF. To evaluate the methodology, we compared our results with Monte Carlo simulations as well as experiments in phantoms with known density and atomic compositions. The dose distributions obtained through applying ICF to TG43 protocol agreed very well with those of Monte Carlo simulations and experiments in all phantoms. In all cases, the mean relative error was reduced by at least a factor of two when ICF correction factor was applied to the TG43 protocol. In conclusion we have developed a new analytical dose calculation method, which enables personalized dose calculations in heterogeneous media using CT images. The methodology offers several advantages including the use of standard TG43 formalism, fast calculation time and extraction of the ICF parameters directly from Hounsfield Units. The methodology was implemented into our clinical treatment planning system where a cohort of 140 patients were processed to study the clinical benefits of a heterogeneity corrected dose.

The ACTTION–APS–AAPM Pain Taxonomy (AAAPT) Multidimensional Approach to Classifying Acute Pain Conditions

PubMed Central

Kent, Michael L.; Tighe, Patrick J.; Belfer, Inna; Brennan, Timothy J.; Bruehl, Stephen; Brummett, Chad M.; Buckenmaier, Chester C.; Buvanendran, Asokumar; Cohen, Robert I.; Desjardins, Paul; Edwards, David; Fillingim, Roger; Gewandter, Jennifer; Gordon, Debra B.; Hurley, Robert W.; Kehlet, Henrik; Loeser, John D.; Mackey, Sean; McLean, Samuel A.; Polomano, Rosemary; Rahman, Siamak; Raja, Srinivasa; Rowbotham, Michael; Suresh, Santhanam; Schachtel, Bernard; Schreiber, Kristin; Schumacher, Mark; Stacey, Brett; Stanos, Steven; Todd, Knox; Turk, Dennis C.; Weisman, Steven J.; Wu, Christopher; Carr, Daniel B.; Dworkin, Robert H.; Terman, Gregory

2017-01-01

Objective. With the increasing societal awareness of the prevalence and impact of acute pain, there is a need to develop an acute pain classification system that both reflects contemporary mechanistic insights and helps guide future research and treatment. Existing classifications of acute pain conditions are limiting, with a predominant focus on the sensory experience (e.g., pain intensity) and pharmacologic consumption. Consequently, there is a need to more broadly characterize and classify the multidimensional experience of acute pain. Setting. Consensus report following expert panel involving the Analgesic, Anesthetic, and Addiction Clinical Trial Translations, Innovations, Opportunities, and Networks (ACTTION), American Pain Society (APS), and American Academy of Pain Medicine (AAPM). Methods. As a complement to a taxonomy recently developed for chronic pain, the ACTTION public-private partnership with the US Food and Drug Administration, the APS, and the AAPM convened a consensus meeting of experts to develop an acute pain taxonomy using prevailing evidence. Key issues pertaining to the distinct nature of acute pain are presented followed by the agreed-upon taxonomy. The ACTTION-APS-AAPM Acute Pain Taxonomy will include the following dimensions: 1) core criteria, 2) common features, 3) modulating factors, 4) impact/functional consequences, and 5) putative pathophysiologic pain mechanisms. Future efforts will consist of working groups utilizing this taxonomy to develop diagnostic criteria for a comprehensive set of acute pain conditions. Perspective. The ACTTION-APS-AAPM Acute Pain Taxonomy (AAAPT) is a multidimensional acute pain classification system designed to classify acute pain along the following dimensions: 1) core criteria, 2) common features, 3) modulating factors, 4) impact/functional consequences, and 5) putative pathophysiologic pain mechanisms. Conclusions. Significant numbers of patients still suffer from significant acute pain, despite the advent of modern multimodal analgesic strategies. Mismanaged acute pain has a broad societal impact as significant numbers of patients may progress to suffer from chronic pain. An acute pain taxonomy provides a much-needed standardization of clinical diagnostic criteria, which benefits clinical care, research, education, and public policy. For the purposes of the present taxonomy, acute pain is considered to last up to seven days, with prolongation to 30 days being common. The current understanding of acute pain mechanisms poorly differentiates between acute and chronic pain and is often insufficient to distinguish among many types of acute pain conditions. Given the usefulness of the AAPT multidimensional framework, the AAAPT undertook a similar approach to organizing various acute pain conditions. PMID:28482098

The ACTTION-APS-AAPM Pain Taxonomy (AAAPT) Multidimensional Approach to Classifying Acute Pain Conditions.

PubMed

Kent, Michael L; Tighe, Patrick J; Belfer, Inna; Brennan, Timothy J; Bruehl, Stephen; Brummett, Chad M; Buckenmaier, Chester C; Buvanendran, Asokumar; Cohen, Robert I; Desjardins, Paul; Edwards, David; Fillingim, Roger; Gewandter, Jennifer; Gordon, Debra B; Hurley, Robert W; Kehlet, Henrik; Loeser, John D; Mackey, Sean; McLean, Samuel A; Polomano, Rosemary; Rahman, Siamak; Raja, Srinivasa; Rowbotham, Michael; Suresh, Santhanam; Schachtel, Bernard; Schreiber, Kristin; Schumacher, Mark; Stacey, Brett; Stanos, Steven; Todd, Knox; Turk, Dennis C; Weisman, Steven J; Wu, Christopher; Carr, Daniel B; Dworkin, Robert H; Terman, Gregory

2017-05-01

With the increasing societal awareness of the prevalence and impact of acute pain, there is a need to develop an acute pain classification system that both reflects contemporary mechanistic insights and helps guide future research and treatment. Existing classifications of acute pain conditions are limiting, with a predominant focus on the sensory experience (eg, pain intensity) and pharmacologic consumption. Consequently, there is a need to more broadly characterize and classify the multidimensional experience of acute pain. Consensus report following expert panel involving the Analgesic, Anesthetic, and Addiction Clinical Trial Translations, Innovations, Opportunities, and Networks (ACTTION), American Pain Society (APS), and American Academy of Pain Medicine (AAPM). As a complement to a taxonomy recently developed for chronic pain, the ACTTION public-private partnership with the US Food and Drug Administration, the APS, and the AAPM convened a consensus meeting of experts to develop an acute pain taxonomy using prevailing evidence. Key issues pertaining to the distinct nature of acute pain are presented followed by the agreed-upon taxonomy. The ACTTION-APS-AAPM Acute Pain Taxonomy will include the following dimensions: 1) core criteria, 2) common features, 3) modulating factors, 4) impact/functional consequences, and 5) putative pathophysiologic pain mechanisms. Future efforts will consist of working groups utilizing this taxonomy to develop diagnostic criteria for a comprehensive set of acute pain conditions. The ACTTION-APS-AAPM Acute Pain Taxonomy (AAAPT) is a multidimensional acute pain classification system designed to classify acute pain along the following dimensions: 1) core criteria, 2) common features, 3) modulating factors, 4) impact/functional consequences, and 5) putative pathophysiologic pain mechanisms. Significant numbers of patients still suffer from significant acute pain, despite the advent of modern multimodal analgesic strategies. Mismanaged acute pain has a broad societal impact as significant numbers of patients may progress to suffer from chronic pain. An acute pain taxonomy provides a much-needed standardization of clinical diagnostic criteria, which benefits clinical care, research, education, and public policy. For the purposes of the present taxonomy, acute pain is considered to last up to seven days, with prolongation to 30 days being common. The current understanding of acute pain mechanisms poorly differentiates between acute and chronic pain and is often insufficient to distinguish among many types of acute pain conditions. Given the usefulness of the AAPT multidimensional framework, the AAAPT undertook a similar approach to organizing various acute pain conditions. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

Image guidance doses delivered during radiotherapy: Quantification, management, and reduction: Report of the AAPM Therapy Physics Committee Task Group 180.

PubMed

Ding, George X; Alaei, Parham; Curran, Bruce; Flynn, Ryan; Gossman, Michael; Mackie, T Rock; Miften, Moyed; Morin, Richard; Xu, X George; Zhu, Timothy C

2018-05-01

With radiotherapy having entered the era of image guidance, or image-guided radiation therapy (IGRT), imaging procedures are routinely performed for patient positioning and target localization. The imaging dose delivered may result in excessive dose to sensitive organs and potentially increase the chance of secondary cancers and, therefore, needs to be managed. This task group was charged with: a) providing an overview on imaging dose, including megavoltage electronic portal imaging (MV EPI), kilovoltage digital radiography (kV DR), Tomotherapy MV-CT, megavoltage cone-beam CT (MV-CBCT) and kilovoltage cone-beam CT (kV-CBCT), and b) providing general guidelines for commissioning dose calculation methods and managing imaging dose to patients. We briefly review the dose to radiotherapy (RT) patients resulting from different image guidance procedures and list typical organ doses resulting from MV and kV image acquisition procedures. We provide recommendations for managing the imaging dose, including different methods for its calculation, and techniques for reducing it. The recommended threshold beyond which imaging dose should be considered in the treatment planning process is 5% of the therapeutic target dose. Although the imaging dose resulting from current kV acquisition procedures is generally below this threshold, the ALARA principle should always be applied in practice. Medical physicists should make radiation oncologists aware of the imaging doses delivered to patients under their care. Balancing ALARA with the requirement for effective target localization requires that imaging dose be managed based on the consideration of weighing risks and benefits to the patient. © 2018 American Association of Physicists in Medicine.

Verification of monitor unit calculations for non-IMRT clinical radiotherapy: report of AAPM Task Group 114.

PubMed

Stern, Robin L; Heaton, Robert; Fraser, Martin W; Goddu, S Murty; Kirby, Thomas H; Lam, Kwok Leung; Molineu, Andrea; Zhu, Timothy C

2011-01-01

The requirement of an independent verification of the monitor units (MU) or time calculated to deliver the prescribed dose to a patient has been a mainstay of radiation oncology quality assurance. The need for and value of such a verification was obvious when calculations were performed by hand using look-up tables, and the verification was achieved by a second person independently repeating the calculation. However, in a modern clinic using CT/MR/PET simulation, computerized 3D treatment planning, heterogeneity corrections, and complex calculation algorithms such as convolution/superposition and Monte Carlo, the purpose of and methodology for the MU verification have come into question. In addition, since the verification is often performed using a simpler geometrical model and calculation algorithm than the primary calculation, exact or almost exact agreement between the two can no longer be expected. Guidelines are needed to help the physicist set clinically reasonable action levels for agreement. This report addresses the following charges of the task group: (1) To re-evaluate the purpose and methods of the "independent second check" for monitor unit calculations for non-IMRT radiation treatment in light of the complexities of modern-day treatment planning. (2) To present recommendations on how to perform verification of monitor unit calculations in a modern clinic. (3) To provide recommendations on establishing action levels for agreement between primary calculations and verification, and to provide guidance in addressing discrepancies outside the action levels. These recommendations are to be used as guidelines only and shall not be interpreted as requirements.

RECORDS: improved Reporting of montE CarlO RaDiation transport Studies: Report of the AAPM Research Committee Task Group 268.

PubMed

Sechopoulos, Ioannis; Rogers, D W O; Bazalova-Carter, Magdalena; Bolch, Wesley E; Heath, Emily C; McNitt-Gray, Michael F; Sempau, Josep; Williamson, Jeffrey F

2018-01-01

Studies involving Monte Carlo simulations are common in both diagnostic and therapy medical physics research, as well as other fields of basic and applied science. As with all experimental studies, the conditions and parameters used for Monte Carlo simulations impact their scope, validity, limitations, and generalizability. Unfortunately, many published peer-reviewed articles involving Monte Carlo simulations do not provide the level of detail needed for the reader to be able to properly assess the quality of the simulations. The American Association of Physicists in Medicine Task Group #268 developed guidelines to improve reporting of Monte Carlo studies in medical physics research. By following these guidelines, manuscripts submitted for peer-review will include a level of relevant detail that will increase the transparency, the ability to reproduce results, and the overall scientific value of these studies. The guidelines include a checklist of the items that should be included in the Methods, Results, and Discussion sections of manuscripts submitted for peer-review. These guidelines do not attempt to replace the journal reviewer, but rather to be a tool during the writing and review process. Given the varied nature of Monte Carlo studies, it is up to the authors and the reviewers to use this checklist appropriately, being conscious of how the different items apply to each particular scenario. It is envisioned that this list will be useful both for authors and for reviewers, to help ensure the adequate description of Monte Carlo studies in the medical physics literature. © 2017 American Association of Physicists in Medicine.

Calculations of two new dose metrics proposed by AAPM Task Group 111 using the measurements with standard CT dosimetry phantoms

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Xinhua; Zhang, Da; Liu, Bob

2013-08-15

Purpose: AAPM Task Group 111 proposed to measure the equilibrium dose-pitch product D-caret{sub eq} for scan modes involving table translation and the midpoint dose D{sub L}(0) for stationary-table modes on the central and peripheral axes of sufficiently long (e.g., at least 40 cm) phantoms. This paper presents an alternative approach to calculate both metrics using the measurements of scanning the standard computed tomographic (CT) dosimetry phantoms on CT scanners.Methods: D-caret{sub eq} was calculated from CTDI{sub 100} and ε(CTDI{sub 100}) (CTDI{sub 100} efficiency), and D{sub L}(0) was calculated from D-caret{sub eq} and the approach to equilibrium function H(L) =D{sub L}(0)/D{sub eq},more » where D{sub eq} was the equilibrium dose. CTDI{sub 100} may be directly obtained from several sources (such as medical physicist's CT scanner performance evaluation or the IMPACT CT patient dosimetry calculator), or be derived from CTDI{sub Vol} using the central to peripheral CTDI{sub 100} ratio (R{sub 100}). The authors have provided the required ε(CTDI{sub 100}) and H(L) data in two previous papers [X. Li, D. Zhang, and B. Liu, Med. Phys. 39, 901–905 (2012); and ibid. 40, 031903 (10pp.) (2013)]. R{sub 100} was assessed for a series of GE, Siemens, Philips, and Toshiba CT scanners with multiple settings of scan field of view, tube voltage, and bowtie filter.Results: The calculated D{sub L}(0) and D{sub L}(0)/D{sub eq} in PMMA and water cylinders were consistent with the measurements on two GE CT scanners (LightSpeed 16 and VCT) by Dixon and Ballard [Med. Phys. 34, 3399–3413 (2007)], the measurements on a Siemens CT scanner (SOMATOM Spirit Power) by Descamps et al. [J. Appl. Clin. Med. Phys. 13, 293–302 (2012)], and the Monte Carlo simulations by Boone [Med. Phys. 36, 4547–4554 (2009)].Conclusions: D-caret{sub eq} and D{sub L}(0) can be calculated using the alternative approach. The authors have provided the required ε(CTDI{sub 100}) and H(L) data in two previous papers. R{sub 100} is presented for a majority of multidetector CT scanners currently on the market, and can be easily assessed for other CT scanners or operating conditions not covered in this study. The central to peripheral D{sub eq} ratio is about 1.50 and 1.12 times of R{sub 100} for the 32- and 16-cm diameter PMMA phantom, respectively.« less

TU-E-BRB-03: Overview of Proposed TG-132 Recommendations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brock, K.

2015-06-15

Deformable image registration (DIR) is developing rapidly and is poised to substantially improve dose fusion accuracy for adaptive and retreatment planning and motion management and PET fusion to enhance contour delineation for treatment planning. However, DIR dose warping accuracy is difficult to quantify, in general, and particularly difficult to do so on a patient-specific basis. As clinical DIR options become more widely available, there is an increased need to understand the implications of incorporating DIR into clinical workflow. Several groups have assessed DIR accuracy in clinically relevant scenarios, but no comprehensive review material is yet available. This session will alsomore » discuss aspects of the AAPM Task Group 132 on the Use of Image Registration and Data Fusion Algorithms and Techniques in Radiotherapy Treatment Planning official report, which provides recommendations for DIR clinical use. We will summarize and compare various commercial DIR software options, outline successful clinical techniques, show specific examples with discussion of appropriate and inappropriate applications of DIR, discuss the clinical implications of DIR, provide an overview of current DIR error analysis research, review QA options and research phantom development and present TG-132 recommendations. Learning Objectives: Compare/contrast commercial DIR software and QA options Overview clinical DIR workflow for retreatment To understand uncertainties introduced by DIR Review TG-132 proposed recommendations.« less

TU-G-BRD-04: A Round Robin Dosimetry Intercomparison of Gamma Stereotactic Radiosurgery Calibration Protocols

DOE Office of Scientific and Technical Information (OSTI.GOV)

Drzymala, R; Alvarez, P; Bednarz, G

2015-06-15

Purpose: The purpose of this multi-institutional study was to compare two new gamma stereotactic radiosurgery (GSRS) dosimetry protocols to existing calibration methods. The ultimate goal was to guide AAPM Task Group 178 in recommending a standard GSRS dosimetry protocol. Methods: Nine centers (ten GSRS units) participated in the study. Each institution made eight sets of dose rate measurements: six with two different ionization chambers in three different 160mm-diameter spherical phantoms (ABS plastic, Solid Water and liquid water), and two using the same ionization chambers with a custom in-air positioning jig. Absolute dose rates were calculated using a newly proposed formalismmore » by the IAEA working group for small and non-standard radiation fields and with a new air-kerma based protocol. The new IAEA protocol requires an in-water ionization chamber calibration and uses previously reported Monte-Carlo generated factors to account for the material composition of the phantom, the type of ionization chamber, and the unique GSRS beam configuration. Results obtained with the new dose calibration protocols were compared to dose rates determined by the AAPM TG-21 and TG-51 protocols, with TG-21 considered as the standard. Results: Averaged over all institutions, ionization chambers and phantoms, the mean dose rate determined with the new IAEA protocol relative to that determined with TG-21 in the ABS phantom was 1.000 with a standard deviation of 0.008. For TG-51, the average ratio was 0.991 with a standard deviation of 0.013, and for the new in-air formalism it was 1.008 with a standard deviation of 0.012. Conclusion: Average results with both of the new protocols agreed with TG-21 to within one standard deviation. TG-51, which does not take into account the unique GSRS beam configuration or phantom material, was not expected to perform as well as the new protocols. The new IAEA protocol showed remarkably good agreement with TG-21. Conflict of Interests: Paula Petti, Josef Novotny, Gennady Neyman and Steve Goetsch are consultants for Elekta Instrument A/B; Elekta Instrument AB, PTW Freiburg GmbH, Standard Imaging, Inc., and The Phantom Laboratory, Inc. loaned equipment for use in these experiments; The University of Wisconsin Accredited Dosimetry Calibration Laboratory provided calibration services.« less

Dose specification for radiation therapy: dose to water or dose to medium?

NASA Astrophysics Data System (ADS)

Ma, C.-M.; Li, Jinsheng

2011-05-01

The Monte Carlo method enables accurate dose calculation for radiation therapy treatment planning and has been implemented in some commercial treatment planning systems. Unlike conventional dose calculation algorithms that provide patient dose information in terms of dose to water with variable electron density, the Monte Carlo method calculates the energy deposition in different media and expresses dose to a medium. This paper discusses the differences in dose calculated using water with different electron densities and that calculated for different biological media and the clinical issues on dose specification including dose prescription and plan evaluation using dose to water and dose to medium. We will demonstrate that conventional photon dose calculation algorithms compute doses similar to those simulated by Monte Carlo using water with different electron densities, which are close (<4% differences) to doses to media but significantly different (up to 11%) from doses to water converted from doses to media following American Association of Physicists in Medicine (AAPM) Task Group 105 recommendations. Our results suggest that for consistency with previous radiation therapy experience Monte Carlo photon algorithms report dose to medium for radiotherapy dose prescription, treatment plan evaluation and treatment outcome analysis.

TU-E-BRB-00: Deformable Image Registration: Is It Right for Your Clinic

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

2015-06-15

Deformable image registration (DIR) is developing rapidly and is poised to substantially improve dose fusion accuracy for adaptive and retreatment planning and motion management and PET fusion to enhance contour delineation for treatment planning. However, DIR dose warping accuracy is difficult to quantify, in general, and particularly difficult to do so on a patient-specific basis. As clinical DIR options become more widely available, there is an increased need to understand the implications of incorporating DIR into clinical workflow. Several groups have assessed DIR accuracy in clinically relevant scenarios, but no comprehensive review material is yet available. This session will alsomore » discuss aspects of the AAPM Task Group 132 on the Use of Image Registration and Data Fusion Algorithms and Techniques in Radiotherapy Treatment Planning official report, which provides recommendations for DIR clinical use. We will summarize and compare various commercial DIR software options, outline successful clinical techniques, show specific examples with discussion of appropriate and inappropriate applications of DIR, discuss the clinical implications of DIR, provide an overview of current DIR error analysis research, review QA options and research phantom development and present TG-132 recommendations. Learning Objectives: Compare/contrast commercial DIR software and QA options Overview clinical DIR workflow for retreatment To understand uncertainties introduced by DIR Review TG-132 proposed recommendations.« less

MicroCT imaging dose to mouse organs using a validated Monte Carlo model of the small animal radiation research platform (SARRP)

NASA Astrophysics Data System (ADS)

Johnstone, Christopher Daniel; Bazalova-Carter, Magdalena

2018-06-01

The goal of this work was to establish imaging dose to mouse organs with a validated Monte Carlo (MC) model of the image-guided Small Animal Radiation Research Platform (SARRP) and to investigate the effect of scatter from the internal walls on animal therapy dose determination. A MC model of the SARRP was built in the BEAMnrc code and validated with a series of homogeneous and heterogeneous phantom measurements. A segmented microCT scan of a mouse was used in DOSXYZnrc to determine mouse organ microCT imaging doses to 15–35 g mice for the SARRP pancake (mouse lying on couch) and standard (mouse standing on couch) imaging geometries for 40–80 kVp tube voltages. Imaging dose for off-center positioning shifts and maintaining image noise across tube voltages were also calculated. Half-value layer (HVL) measurements for the 220 kVp therapy beam in the presence of the SARRP shielding cabinet were modeled in BEAMnrc and compared to the 100 cm source-to-detector distance (SDD) in the scatter free, narrow-beam geometry recommended by the American Association of Physicists in Medicine Task Group 61 (AAPM TG-61). For a 60 kVp, 0.8 mA, and 60 s scan protocol, maximum mean organ imaging doses to boney and non-boney structures were 10.5 cGy and 3.5 cGy, respectively, for an average size 20 g mouse. Current-exposure combinations above 323, 203, 147, 116, and 95 mAs for 40–80 kVp tube voltages, respectively, will increase body doses above 10 cGy. MicroCT mean body dose was 18% lower in pancake compared to standard imaging geometry. An 11% difference in measured HVL at a 50 cm SDD was found compared to MC simulated HVL for the AAPM TG-61 recommended scatter free geometry at a 100 cm SDD. This change in HVL resulted in a 0.5% change in absorbed dose to water calculations for the treatment beam.

SU-E-I-20: Comprehensive Quality Assurance Test of Second Generation Toshiba Aquilion Large Bore CT Simulator Based On AAPM TG-66 Recommendations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, D

2015-06-15

Purpose: AAPM radiation therapy committee task group No. 66 (TG-66) published a report which described a general approach to CT simulator QA. The report outlines the testing procedures and specifications for the evaluation of patient dose, radiation safety, electromechanical components, and image quality for a CT simulator. The purpose of this study is to thoroughly evaluate the performance of a second generation Toshiba Aquilion Large Bore CT simulator with 90 cm bore size (Toshiba, Nasu, JP) based on the TG-66 criteria. The testing procedures and results from this study provide baselines for a routine QA program. Methods: Different measurements andmore » analysis were performed including CTDIvol measurements, alignment and orientation of gantry lasers, orientation of the tabletop with respect to the imaging plane, table movement and indexing accuracy, Scanogram location accuracy, high contrast spatial resolution, low contrast resolution, field uniformity, CT number accuracy, mA linearity and mA reproducibility using a number of different phantoms and measuring devices, such as CTDI phantom, ACR image quality phantom, TG-66 laser QA phantom, pencil ion chamber (Fluke Victoreen) and electrometer (RTI Solidose 400). Results: The CTDI measurements were within 20% of the console displayed values. The alignment and orientation for both gantry laser and tabletop, as well as the table movement and indexing and scanogram location accuracy were within 2mm as specified in TG66. The spatial resolution, low contrast resolution, field uniformity and CT number accuracy were all within ACR’s recommended limits. The mA linearity and reproducibility were both well below the TG66 threshold. Conclusion: The 90 cm bore size second generation Toshiba Aquilion Large Bore CT simulator that comes with 70 cm true FOV can consistently meet various clinical needs. The results demonstrated that this simulator complies with the TG-66 protocol in all aspects including electromechanical component, radiation safety component, and image quality component. Employee of Toshiba America Medical Systems.« less

Quality assurance and training procedures for computer-aided detection and diagnosis systems in clinical usea)

PubMed Central

Huo, Zhimin; Summers, Ronald M.; Paquerault, Sophie; Lo, Joseph; Hoffmeister, Jeffrey; Armato, Samuel G.; Freedman, Matthew T.; Lin, Jesse; Ben Lo, Shih-Chung; Petrick, Nicholas; Sahiner, Berkman; Fryd, David; Yoshida, Hiroyuki; Chan, Heang-Ping

2013-01-01

Computer-aided detection/diagnosis (CAD) is increasingly used for decision support by clinicians for detection and interpretation of diseases. However, there are no quality assurance (QA) requirements for CAD in clinical use at present. QA of CAD is important so that end users can be made aware of changes in CAD performance both due to intentional or unintentional causes. In addition, end-user training is critical to prevent improper use of CAD, which could potentially result in lower overall clinical performance. Research on QA of CAD and user training are limited to date. The purpose of this paper is to bring attention to these issues, inform the readers of the opinions of the members of the American Association of Physicists in Medicine (AAPM) CAD subcommittee, and thus stimulate further discussion in the CAD community on these topics. The recommendations in this paper are intended to be work items for AAPM task groups that will be formed to address QA and user training issues on CAD in the future. The work items may serve as a framework for the discussion and eventual design of detailed QA and training procedures for physicists and users of CAD. Some of the recommendations are considered by the subcommittee to be reasonably easy and practical and can be implemented immediately by the end users; others are considered to be “best practice” approaches, which may require significant effort, additional tools, and proper training to implement. The eventual standardization of the requirements of QA procedures for CAD will have to be determined through consensus from members of the CAD community, and user training may require support of professional societies. It is expected that high-quality CAD and proper use of CAD could allow these systems to achieve their true potential, thus benefiting both the patients and the clinicians, and may bring about more widespread clinical use of CAD for many other diseases and applications. It is hoped that the awareness of the need for appropriate CAD QA and user training will stimulate new ideas and approaches for implementing such procedures efficiently and effectively as well as funding opportunities to fulfill such critical efforts. PMID:23822459

MO-E-9A-01: Risk Based Quality Management: TG100 In Action

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huq, M; Palta, J; Dunscombe, P

2014-06-15

One of the goals of quality management in radiation therapy is to gain high confidence that patients will receive the prescribed treatment correctly. To accomplish these goals professional societies such as the American Association of Physicists in Medicine (AAPM) has published many quality assurance (QA), quality control (QC), and quality management (QM) guidance documents. In general, the recommendations provided in these documents have emphasized on performing device-specific QA at the expense of process flow and protection of the patient against catastrophic errors. Analyses of radiation therapy incidents find that they are most often caused by flaws in the overall therapymore » process, from initial consult through final treatment, than by isolated hardware or computer failures detectable by traditional physics QA. This challenge is shared by many intrinsically hazardous industries. Risk assessment tools and analysis techniques have been developed to define, identify, and eliminate known and/or potential failures, problems, or errors, from a system, process and/or service before they reach the customer. These include, but are not limited to, process mapping, failure modes and effects analysis (FMEA), fault tree analysis (FTA), and establishment of a quality management program that best avoids the faults and risks that have been identified in the overall process. These tools can be easily adapted to radiation therapy practices because of their simplicity and effectiveness to provide efficient ways to enhance the safety and quality of treatment processes. Task group 100 (TG100) of AAPM has developed a risk-based quality management program that uses these tools. This session will be devoted to a discussion of these tools and how these tools can be used in a given radiotherapy clinic to develop a risk based QM program. Learning Objectives: Learn how to design a process map for a radiotherapy process. Learn how to perform a FMEA analysis for a given process. Learn what Fault tree analysis is all about. Learn how to design a quality management program based upon the information obtained from process mapping, FMEA and FTA.« less

WE-AB-213-01: AAPM Projects and Collaborations in Africa

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shulman, A.

AAPM projects and collaborations in Africa Adam Shulman (AA-SC Chair) The African Affairs Subcommittee (AA-SC) of the AAPM will present a multi-institutional approach to medical physics support in Africa. Current work to increase the quality of care and level of safety for the medical physics practice in Senegal, Ghana, and Zimbabwe will be presented, along with preliminary projects in Nigeria and Botswana. Because the task of addressing the needs of medical physics in countries across Africa is larger than one entity can accomplish on its own, the AA-SC has taken the approach of joining forces with multiple organizations such asmore » Radiating Hope and TreatSafely (NGO’s), the IAEA, companies like BrainLab, Varian and Elekta, medical volunteers and academic institutions such as NYU and Washington University. Elements of current projects include: 1) Distance training and evaluation of the quality of contouring and treatment planning, teaching treatment planning and other subjects, and troubleshooting using modern telecommunications technology in Senegal, Ghana, and Zimbabwe; 2) Assistance in the transition from 2D to 3D in Senegal and Zimbabwe; 3) Assistance in the transition from 3D to IMRT using in-house compensators in Senegal; 4) Modernizing the cancer center in Senegal and increasing safety and; 5) Training on on 3D techniques in Ghana; 6) Assisting a teaching and training radiation oncology center to be built in Zimbabwe; 7) Working with the ISEP Program in Sub-Saharan Africa; 8) Creating instructional videos on linac commissioning; 9) Working on a possible collaboration to train physicists in Nigeria. Building on past achievements, the subcommittee seeks to make a larger impact on the continent, as the number and size of projects increases and more human resources become available. The State of Medical Physics Collaborations and Projects in Latin America Sandra Guzman (Peru) The lack of Medical Physicists (MP) in many Latin American (LA) countries leads to recruitment of professionals with incomplete education. In most LA countries only one MP responsible for each Center is currently mandated. Currently there is a large disparity among MP training programs and there is significant debate about the standards of MP graduate education in many LA countries. There are no commonly recognized academic programs, not enough clinical training sites and clinical training is not typically considered as part of the MP work. Economic pressures and high workloads also impede the creation of more training centers. The increasing need of qualified MPs require establishing a coordinated system of national Education & Training Centers (ETC), to meet the international standards of education and training in Medical Physics. This shortfall calls for support of organizations such as the IOMP, AAPM, ALFIM, IAEA, etc. Examples from various LA countries, as well as some proposed solutions, will be presented. In particular, we will discuss the resources that the AAPM and its members can offer to support regional programs. The ‘Medical Imaging’ physicist in the emerging world: Challenges and opportunities - Caridad Borrás (WGNIMP Chair) While the role of radiation therapy physicists in the emerging world is reasonably well established, the role of medical imaging physicists is not. The only perceived needs in radiology departments are equipment quality control and radiation protection, tasks that can be done by a technologist or a service engineer. To change the situation, the International Basic Safety Standard, which is adopted/adapted world-wide as national radiation protection regulations, states: “For diagnostic radiological procedures and image guided interventional procedures, the requirements of these Standards for medical imaging, calibration, dosimetry and quality assurance, including the acceptance and commissioning of medical radiological equipment, are fulfilled by or under the oversight of, or with the documented advice of a medical physicist, whose degree of involvement is determined by the complexity of the radiological procedures and the associated radiation risks”. Details on how these requirements can be carried out in resource-limited settings will be described. IAEA support to medical physics in Africa and Latin America: achievements and challenges Ahmed Meghzifene (IAEA) Shortage of clinically qualified medical physicists in radiotherapy and imaging, insufficient and inadequate education and training programs, as well as a lack of professional recognition were identified as the main issues to be addressed by the IAEA. The IAEA developed a series of integrated projects aiming specifically at promoting the essential role of medical physicists in health care, developing harmonized guidelines on dosimetry and quality assurance, and supporting education and clinical training programs. The unique feature of the IAEA approach is support it provides for implementation of guidelines and education programs in Member States through its technical cooperation project. The presentation will summarize IAEA support to Latin America and Africa in the field of medical physics and will highlight how the new International Basic Safety Standards are expected to impact the medical physics practice in low and middle income countries. Learning Objectives: Learn about the shortage of qualified Medical Physicists in Africa and Latin America. Understand the reasons of this shortage. Learn about the ways to improve the situation and AAPM role in this process.« less

The ACTTION-APS-AAPM Pain Taxonomy (AAAPT) Multidimensional Approach to Classifying Acute Pain Conditions.

PubMed

Kent, Michael L; Tighe, Patrick J; Belfer, Inna; Brennan, Timothy J; Bruehl, Stephen; Brummett, Chad M; Buckenmaier, Chester C; Buvanendran, Asokumar; Cohen, Robert I; Desjardins, Paul; Edwards, David; Fillingim, Roger; Gewandter, Jennifer; Gordon, Debra B; Hurley, Robert W; Kehlet, Henrik; Loeser, John D; Mackey, Sean; McLean, Samuel A; Polomano, Rosemary; Rahman, Siamak; Raja, Srinivasa; Rowbotham, Michael; Suresh, Santhanam; Schachtel, Bernard; Schreiber, Kristin; Schumacher, Mark; Stacey, Brett; Stanos, Steven; Todd, Knox; Turk, Dennis C; Weisman, Steven J; Wu, Christopher; Carr, Daniel B; Dworkin, Robert H; Terman, Gregory

2017-05-01

With the increasing societal awareness of the prevalence and impact of acute pain, there is a need to develop an acute pain classification system that both reflects contemporary mechanistic insights and helps guide future research and treatment. Existing classifications of acute pain conditions are limiting, with a predominant focus on the sensory experience (e.g., pain intensity) and pharmacologic consumption. Consequently, there is a need to more broadly characterize and classify the multidimensional experience of acute pain. Consensus report following expert panel involving the Analgesic, Anesthetic, and Addiction Clinical Trial Translations, Innovations, Opportunities, and Networks (ACTTION), American Pain Society (APS), and American Academy of Pain Medicine (AAPM). As a complement to a taxonomy recently developed for chronic pain, the ACTTION public-private partnership with the US Food and Drug Administration, the APS, and the AAPM convened a consensus meeting of experts to develop an acute pain taxonomy using prevailing evidence. Key issues pertaining to the distinct nature of acute pain are presented followed by the agreed-upon taxonomy. The ACTTION-APS-AAPM Acute Pain Taxonomy will include the following dimensions: 1) core criteria, 2) common features, 3) modulating factors, 4) impact/functional consequences, and 5) putative pathophysiologic pain mechanisms. Future efforts will consist of working groups utilizing this taxonomy to develop diagnostic criteria for a comprehensive set of acute pain conditions. The ACTTION-APS-AAPM Acute Pain Taxonomy (AAAPT) is a multidimensional acute pain classification system designed to classify acute pain along the following dimensions: 1) core criteria, 2) common features, 3) modulating factors, 4) impact/functional consequences, and 5) putative pathophysiologic pain mechanisms. Significant numbers of patients still suffer from significant acute pain, despite the advent of modern multimodal analgesic strategies. Mismanaged acute pain has a broad societal impact as significant numbers of patients may progress to suffer from chronic pain. An acute pain taxonomy provides a much-needed standardization of clinical diagnostic criteria, which benefits clinical care, research, education, and public policy. For the purposes of the present taxonomy, acute pain is considered to last up to seven days, with prolongation to 30 days being common. The current understanding of acute pain mechanisms poorly differentiates between acute and chronic pain and is often insufficient to distinguish among many types of acute pain conditions. Given the usefulness of the AAPT multidimensional framework, the AAAPT undertook a similar approach to organizing various acute pain conditions. © 2017 American Academy of Pain Medicine. This article has been co-published in Pain Medicine and The Journal of Pain. This is an Open Access article distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs licence (http://creativecommons.org/licenses/by-nc-nd/4.0/), which permits non-commercial reproduction and distribution of the work, in any medium, provided the original work is not altered or transformed in any way, and that the work is properly cited. For commercial re-use, please contact journals.permissions@oup.com.

The value transformation of health care: Impact on neuromuscular and electrodiagnostic medicine.

PubMed

Narayanaswami, Pushpa; Suk, Millie; Jones, Lyell K

2017-10-01

Beginning in 2017, most physicians who participate in Medicare are subject to the Medicare Access and CHIP Reauthorization Act (MACRA), the milestone legislation that signals the US health care system's transition from volume-based to value-based care. Here we review emerging trends in development of value-based healthcare systems in the US. MACRA and the resulting Quality Payment Program create 2 participation pathways, the Merit-based Incentive Payment System (MIPS) and the Advanced Alternative Payment Model (AAPM) pathway. Although there are several program incentives for AAPM participation, to date there have been few AAPM options for specialists. MIPS and its widening bonus and penalty window will likely be the primary participation pathway in the early years of the program. Value-based payment has the potential to reshape health care delivery in the United States, with implications for neuromuscular and electrodiagnostic (EDX) specialists. Meaningful quality measures are required for neuromuscular and EDX specialists. Muscle Nerve 56: 679-683, 2017. © 2017 Wiley Periodicals, Inc.

Association of church-sponsored activity participation and prevalence of overweight and obesity in African American Protestants, National Survey of American Life, 2001-2003.

PubMed

Taylor, Jerome; Belay, Brook; Park, Sohyun; Onufrak, Stephen; Dietz, William

2013-01-01

This study examines the relationships between participation in the African American church and overweight/obesity (body mass index (BMI) > or = 25 kg/m2). This cross-sectional analysis was based on the National Survey of American Life 2001-2003 and included 2,689 African American Protestant (AAP) adults. Multivariate logistic regression was used to calculate adjusted odds ratios (aOR) and 95% confidence intervals (CI) for overweight/obesity. Two practices were examined--frequency of participation in church activities (excluding services) and frequency of church service attendance. Each practice was analyzed in separate models. Each model included the following covariates: age, marital status, education, poverty, smoking, and region of country. We also adjusted models for sex. After adjustment, African American Protestant men (AAPM) who participated in church activities at least weekly were more likely to be overweight/obese (aOR=2.17; 95% CI = 1.25, 3.77) compared to AAPM who did not participate in church activities. There was no statistically significant association between overweight/obesity and participation in church activities for AAPW. There was no association between overweight/obesity and attendance of church services for AAP men and women combined. For AAPM, participation in church activities was significantly associated with overweight/obesity. Further studies are required to determine why this association occurs in AAPM but not AAPW. Studies looking at the wider application of the several successful health initiatives targeting the AAP community should also be considered.

Estimating peak skin and eye lens dose from neuroperfusion examinations: use of Monte Carlo based simulations and comparisons to CTDIvol, AAPM Report No. 111, and ImPACT dosimetry tool values.

PubMed

Zhang, Di; Cagnon, Chris H; Villablanca, J Pablo; McCollough, Cynthia H; Cody, Dianna D; Zankl, Maria; Demarco, John J; McNitt-Gray, Michael F

2013-09-01

CT neuroperfusion examinations are capable of delivering high radiation dose to the skin or lens of the eyes of a patient and can possibly cause deterministic radiation injury. The purpose of this study is to: (a) estimate peak skin dose and eye lens dose from CT neuroperfusion examinations based on several voxelized adult patient models of different head size and (b) investigate how well those doses can be approximated by some commonly used CT dose metrics or tools, such as CTDIvol, American Association of Physicists in Medicine (AAPM) Report No. 111 style peak dose measurements, and the ImPACT organ dose calculator spreadsheet. Monte Carlo simulation methods were used to estimate peak skin and eye lens dose on voxelized patient models, including GSF's Irene, Frank, Donna, and Golem, on four scanners from the major manufacturers at the widest collimation under all available tube potentials. Doses were reported on a per 100 mAs basis. CTDIvol measurements for a 16 cm CTDI phantom, AAPM Report No. 111 style peak dose measurements, and ImPACT calculations were performed for available scanners at all tube potentials. These were then compared with results from Monte Carlo simulations. The dose variations across the different voxelized patient models were small. Dependent on the tube potential and scanner and patient model, CTDIvol values overestimated peak skin dose by 26%-65%, and overestimated eye lens dose by 33%-106%, when compared to Monte Carlo simulations. AAPM Report No. 111 style measurements were much closer to peak skin estimates ranging from a 14% underestimate to a 33% overestimate, and with eye lens dose estimates ranging from a 9% underestimate to a 66% overestimate. The ImPACT spreadsheet overestimated eye lens dose by 2%-82% relative to voxelized model simulations. CTDIvol consistently overestimates dose to eye lens and skin. The ImPACT tool also overestimated dose to eye lenses. As such they are still useful as a conservative predictor of dose for CT neuroperfusion studies. AAPM Report No. 111 style measurements are a better predictor of both peak skin and eye lens dose than CTDIvol and ImPACT for the patient models used in this study. It should be remembered that both the AAPM Report No. 111 peak dose metric and CTDIvol dose metric are dose indices and were not intended to represent actual organ doses.

Estimating peak skin and eye lens dose from neuroperfusion examinations: Use of Monte Carlo based simulations and comparisons to CTDIvol, AAPM Report No. 111, and ImPACT dosimetry tool values

PubMed Central

Zhang, Di; Cagnon, Chris H.; Villablanca, J. Pablo; McCollough, Cynthia H.; Cody, Dianna D.; Zankl, Maria; Demarco, John J.; McNitt-Gray, Michael F.

2013-01-01

Purpose: CT neuroperfusion examinations are capable of delivering high radiation dose to the skin or lens of the eyes of a patient and can possibly cause deterministic radiation injury. The purpose of this study is to: (a) estimate peak skin dose and eye lens dose from CT neuroperfusion examinations based on several voxelized adult patient models of different head size and (b) investigate how well those doses can be approximated by some commonly used CT dose metrics or tools, such as CTDIvol, American Association of Physicists in Medicine (AAPM) Report No. 111 style peak dose measurements, and the ImPACT organ dose calculator spreadsheet. Methods: Monte Carlo simulation methods were used to estimate peak skin and eye lens dose on voxelized patient models, including GSF's Irene, Frank, Donna, and Golem, on four scanners from the major manufacturers at the widest collimation under all available tube potentials. Doses were reported on a per 100 mAs basis. CTDIvol measurements for a 16 cm CTDI phantom, AAPM Report No. 111 style peak dose measurements, and ImPACT calculations were performed for available scanners at all tube potentials. These were then compared with results from Monte Carlo simulations. Results: The dose variations across the different voxelized patient models were small. Dependent on the tube potential and scanner and patient model, CTDIvol values overestimated peak skin dose by 26%–65%, and overestimated eye lens dose by 33%–106%, when compared to Monte Carlo simulations. AAPM Report No. 111 style measurements were much closer to peak skin estimates ranging from a 14% underestimate to a 33% overestimate, and with eye lens dose estimates ranging from a 9% underestimate to a 66% overestimate. The ImPACT spreadsheet overestimated eye lens dose by 2%–82% relative to voxelized model simulations. Conclusions: CTDIvol consistently overestimates dose to eye lens and skin. The ImPACT tool also overestimated dose to eye lenses. As such they are still useful as a conservative predictor of dose for CT neuroperfusion studies. AAPM Report No. 111 style measurements are a better predictor of both peak skin and eye lens dose than CTDIvol and ImPACT for the patient models used in this study. It should be remembered that both the AAPM Report No. 111 peak dose metric and CTDIvol dose metric are dose indices and were not intended to represent actual organ doses. PMID:24007152

Flattening filter-free accelerators: a report from the AAPM Therapy Emerging Technology Assessment Work Group.

PubMed

Xiao, Ying; Kry, Stephen F; Popple, Richard; Yorke, Ellen; Papanikolaou, Niko; Stathakis, Sotirios; Xia, Ping; Huq, Saiful; Bayouth, John; Galvin, James; Yin, Fang-Fang

2015-05-08

This report describes the current state of flattening filter-free (FFF) radiotherapy beams implemented on conventional linear accelerators, and is aimed primarily at practicing medical physicists. The Therapy Emerging Technology Assessment Work Group of the American Association of Physicists in Medicine (AAPM) formed a writing group to assess FFF technology. The published literature on FFF technology was reviewed, along with technical specifications provided by vendors. Based on this information, supplemented by the clinical experience of the group members, consensus guidelines and recommendations for implementation of FFF technology were developed. Areas in need of further investigation were identified. Removing the flattening filter increases beam intensity, especially near the central axis. Increased intensity reduces treatment time, especially for high-dose stereotactic radiotherapy/radiosurgery (SRT/SRS). Furthermore, removing the flattening filter reduces out-of-field dose and improves beam modeling accuracy. FFF beams are advantageous for small field (e.g., SRS) treatments and are appropriate for intensity-modulated radiotherapy (IMRT). For conventional 3D radiotherapy of large targets, FFF beams may be disadvantageous compared to flattened beams because of the heterogeneity of FFF beam across the target (unless modulation is employed). For any application, the nonflat beam characteristics and substantially higher dose rates require consideration during the commissioning and quality assurance processes relative to flattened beams, and the appropriate clinical use of the technology needs to be identified. Consideration also needs to be given to these unique characteristics when undertaking facility planning. Several areas still warrant further research and development. Recommendations pertinent to FFF technology, including acceptance testing, commissioning, quality assurance, radiation safety, and facility planning, are presented. Examples of clinical applications are provided. Several of the areas in which future research and development are needed are also indicated.

TH-E-18A-01: Developments in Monte Carlo Methods for Medical Imaging

DOE Office of Scientific and Technical Information (OSTI.GOV)

Badal, A; Zbijewski, W; Bolch, W

Monte Carlo simulation methods are widely used in medical physics research and are starting to be implemented in clinical applications such as radiation therapy planning systems. Monte Carlo simulations offer the capability to accurately estimate quantities of interest that are challenging to measure experimentally while taking into account the realistic anatomy of an individual patient. Traditionally, practical application of Monte Carlo simulation codes in diagnostic imaging was limited by the need for large computational resources or long execution times. However, recent advancements in high-performance computing hardware, combined with a new generation of Monte Carlo simulation algorithms and novel postprocessing methods,more » are allowing for the computation of relevant imaging parameters of interest such as patient organ doses and scatter-to-primaryratios in radiographic projections in just a few seconds using affordable computational resources. Programmable Graphics Processing Units (GPUs), for example, provide a convenient, affordable platform for parallelized Monte Carlo executions that yield simulation times on the order of 10{sup 7} xray/ s. Even with GPU acceleration, however, Monte Carlo simulation times can be prohibitive for routine clinical practice. To reduce simulation times further, variance reduction techniques can be used to alter the probabilistic models underlying the x-ray tracking process, resulting in lower variance in the results without biasing the estimates. Other complementary strategies for further reductions in computation time are denoising of the Monte Carlo estimates and estimating (scoring) the quantity of interest at a sparse set of sampling locations (e.g. at a small number of detector pixels in a scatter simulation) followed by interpolation. Beyond reduction of the computational resources required for performing Monte Carlo simulations in medical imaging, the use of accurate representations of patient anatomy is crucial to the virtual generation of medical images and accurate estimation of radiation dose and other imaging parameters. For this, detailed computational phantoms of the patient anatomy must be utilized and implemented within the radiation transport code. Computational phantoms presently come in one of three format types, and in one of four morphometric categories. Format types include stylized (mathematical equation-based), voxel (segmented CT/MR images), and hybrid (NURBS and polygon mesh surfaces). Morphometric categories include reference (small library of phantoms by age at 50th height/weight percentile), patient-dependent (larger library of phantoms at various combinations of height/weight percentiles), patient-sculpted (phantoms altered to match the patient's unique outer body contour), and finally, patient-specific (an exact representation of the patient with respect to both body contour and internal anatomy). The existence and availability of these phantoms represents a very important advance for the simulation of realistic medical imaging applications using Monte Carlo methods. New Monte Carlo simulation codes need to be thoroughly validated before they can be used to perform novel research. Ideally, the validation process would involve comparison of results with those of an experimental measurement, but accurate replication of experimental conditions can be very challenging. It is very common to validate new Monte Carlo simulations by replicating previously published simulation results of similar experiments. This process, however, is commonly problematic due to the lack of sufficient information in the published reports of previous work so as to be able to replicate the simulation in detail. To aid in this process, the AAPM Task Group 195 prepared a report in which six different imaging research experiments commonly performed using Monte Carlo simulations are described and their results provided. The simulation conditions of all six cases are provided in full detail, with all necessary data on material composition, source, geometry, scoring and other parameters provided. The results of these simulations when performed with the four most common publicly available Monte Carlo packages are also provided in tabular form. The Task Group 195 Report will be useful for researchers needing to validate their Monte Carlo work, and for trainees needing to learn Monte Carlo simulation methods. In this symposium we will review the recent advancements in highperformance computing hardware enabling the reduction in computational resources needed for Monte Carlo simulations in medical imaging. We will review variance reduction techniques commonly applied in Monte Carlo simulations of medical imaging systems and present implementation strategies for efficient combination of these techniques with GPU acceleration. Trade-offs involved in Monte Carlo acceleration by means of denoising and “sparse sampling” will be discussed. A method for rapid scatter correction in cone-beam CT (<5 min/scan) will be presented as an illustration of the simulation speeds achievable with optimized Monte Carlo simulations. We will also discuss the development, availability, and capability of the various combinations of computational phantoms for Monte Carlo simulation of medical imaging systems. Finally, we will review some examples of experimental validation of Monte Carlo simulations and will present the AAPM Task Group 195 Report. Learning Objectives: Describe the advances in hardware available for performing Monte Carlo simulations in high performance computing environments. Explain variance reduction, denoising and sparse sampling techniques available for reduction of computational time needed for Monte Carlo simulations of medical imaging. List and compare the computational anthropomorphic phantoms currently available for more accurate assessment of medical imaging parameters in Monte Carlo simulations. Describe experimental methods used for validation of Monte Carlo simulations in medical imaging. Describe the AAPM Task Group 195 Report and its use for validation and teaching of Monte Carlo simulations in medical imaging.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Morin, R

The Medical Physics community lost one of its prominent leaders in April, 2013 with the passing of Donald D. Tolbert, PhD. He received his Doctorate at the University of Kansas followed by post Doctoral training at Florida State University and the University of Wisconsin. He was Chief of Radiation Therapy Medical Physics at the University of Wisconsin Hospital for 7 years before relocating to Honolulu Hawaii, where he founded the consulting group Mid-Pacific Medical Physics. Don was a leader in both the AAPM and the ACR, chairing the Professional Council and the Commission on Medical Physics. He was active onmore » the AAPM Board of Directors and a member of the ACR Board of Chancellors. Dr. Tolbert's approach to the difficult problems of the times was admired and respected by colleagues in Medical Physics, Radiation Oncology, and Diagnostic Radiology. He always rose above the heated political rhetoric and led the discussion to higher ground. His wisdom was continually sought to solve complicated problems. Following retirement, he returned to homes in Kansas and Colorado, devoting his time to writing about coping with diabetes and providing support for Seniors in Beloit Kansas. Don is survived by his wife, Mattie, his 3 children and 5 grandchildren. He will be greatly missed.« less

Compliance with AAPM Practice Guideline 1.a: CT Protocol Management and Review — from the perspective of a university hospital

PubMed Central

Bour, Robert K.; Pozniak, Myron; Ranallo, Frank N.

2015-01-01

The purpose of this paper is to describe our experience with the AAPM Medical Physics Practice Guideline 1.a: “CT Protocol Management and Review Practice Guideline”. Specifically, we will share how our institution's quality management system addresses the suggestions within the AAPM practice report. We feel this paper is needed as it was beyond the scope of the AAPM practice guideline to provide specific details on fulfilling individual guidelines. Our hope is that other institutions will be able to emulate some of our practices and that this article would encourage other types of centers (e.g., community hospitals) to share their methodology for approaching CT protocol optimization and quality control. Our institution had a functioning CT protocol optimization process, albeit informal, since we began using CT. Recently, we made our protocol development and validation process compliant with a number of the ISO 9001:2008 clauses and this required us to formalize the roles of the members of our CT protocol optimization team. We rely heavily on PACS‐based IT solutions for acquiring radiologist feedback on the performance of our CT protocols and the performance of our CT scanners in terms of dose (scanner output) and the function of the automatic tube current modulation. Specific details on our quality management system covering both quality control and ongoing optimization have been provided. The roles of each CT protocol team member have been defined, and the critical role that IT solutions provides for the management of files and the monitoring of CT protocols has been reviewed. In addition, the invaluable role management provides by being a champion for the project has been explained; lack of a project champion will mitigate the efforts of a CT protocol optimization team. Meeting the guidelines set forth in the AAPM practice guideline was not inherently difficult, but did, in our case, require the cooperation of radiologists, technologists, physicists, IT, administrative staff, and hospital management. Some of the IT solutions presented in this paper are novel and currently unique to our institution. PACS number: 87.57.Q PMID:26103176

Association Of Church-Sponsored Activity Participation And Prevalence Of Overweight And Obesity In African American Protestants, National Survey Of American Life, 2001–2003

PubMed Central

Taylor, Jerome; Belay, Brook; Park, Sohyun; Onufrak, Stephen; Dietz, William

2015-01-01

Objective This study examines the relationships between participation in the African American church and overweight/obesity (body mass index (BMI) ≥25 kg/m2). Design: This cross-sectional analysis was based on the National Survey of American Life 2001–2003 and included 2,689 African American Protestant (AAP) adults. Multivariate logistic regression was used to calculate adjusted odds ratios (aOR) and 95% confidence intervals (CI) for overweight/obesity. Two practices were examined – frequency of participation in church activities (excluding services) and frequency of church service attendance. Each practice was analyzed in separate models. Each model included the following covariates: age, marital status, education, poverty, smoking, and region of country. We also adjusted models for sex. Results After adjustment, African American Protestant men (AAPM) who participated in church activities at least weekly were more likely to be overweight/obese (aOR=2.17; 95% CI=1.25, 3.77) compared to AAPM who did not participate in church activities. There was no statistically significant association between overweight/obesity and participation in church activities for AAPW. There was no association between overweight/obesity and attendance of church services for AAP men and women combined. Conclusions For AAPM, participation in church activities was significantly associated with overweight/obesity. Further studies are required to determine why this association occurs in AAPM but not AAPW. Studies looking at the wider application of the several successful health initiatives targeting the AAP community should also be considered. PMID:23914418

Medical Physicists and AAPM

NASA Astrophysics Data System (ADS)

Amols, Howard

2006-03-01

The American Association of Physicists in Medicine (AAPM), a member society of the AIP is the largest professional society of medical physicists in the world with nearly 5700 members. Members operate in medical centers, university and community hospitals, research laboratories, industry, and private practice. Medical physics specialties include radiation therapy physics, medical diagnostic and imaging physics, nuclear medicine physics, and medical radiation safety. The majority of AAPM members are based in hospital departments of radiation oncology or radiology and provide technical support for patient diagnosis and treatment in a clinical environment. Job functions include support of clinical care, calibration and quality assurance of medical devices such as linear accelerators for cancer therapy, CT, PET, MRI, and other diagnostic imaging devices, research, and teaching. Pathways into a career in medical physics require an advanced degree in medical physics, physics, engineering, or closely related field, plus clinical training in one or more medical physics specialties (radiation therapy physics, imaging physics, or radiation safety). Most clinically based medical physicists also obtain certification from the American Board of Radiology, and some states require licensure as well.

TU-AB-BRD-00: Task Group 100

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

2015-06-15

Current quality assurance and quality management guidelines provided by various professional organizations are prescriptive in nature, focusing principally on performance characteristics of planning and delivery devices. However, published analyses of events in radiation therapy show that most events are often caused by flaws in clinical processes rather than by device failures. This suggests the need for the development of a quality management program that is based on integrated approaches to process and equipment quality assurance. Industrial engineers have developed various risk assessment tools that are used to identify and eliminate potential failures from a system or a process before amore » failure impacts a customer. These tools include, but are not limited to, process mapping, failure modes and effects analysis, fault tree analysis. Task Group 100 of the American Association of Physicists in Medicine has developed these tools and used them to formulate an example risk-based quality management program for intensity-modulated radiotherapy. This is a prospective risk assessment approach that analyzes potential error pathways inherent in a clinical process and then ranks them according to relative risk, typically before implementation, followed by the design of a new process or modification of the existing process. Appropriate controls are then put in place to ensure that failures are less likely to occur and, if they do, they will more likely be detected before they propagate through the process, compromising treatment outcome and causing harm to the patient. Such a prospective approach forms the basis of the work of Task Group 100 that has recently been approved by the AAPM. This session will be devoted to a discussion of these tools and practical examples of how these tools can be used in a given radiotherapy clinic to develop a risk based quality management program. Learning Objectives: Learn how to design a process map for a radiotherapy process Learn how to perform failure modes and effects analysis analysis for a given process Learn what fault trees are all about Learn how to design a quality management program based upon the information obtained from process mapping, failure modes and effects analysis and fault tree analysis. Dunscombe: Director, TreatSafely, LLC and Center for the Assessment of Radiological Sciences; Consultant to IAEA and Varian Thomadsen: President, Center for the Assessment of Radiological Sciences Palta: Vice President of the Center for the Assessment of Radiological Sciences.« less

A simplified analytical dose calculation algorithm accounting for tissue heterogeneity for low-energy brachytherapy sources.

PubMed

Mashouf, Shahram; Lechtman, Eli; Beaulieu, Luc; Verhaegen, Frank; Keller, Brian M; Ravi, Ananth; Pignol, Jean-Philippe

2013-09-21

The American Association of Physicists in Medicine Task Group No. 43 (AAPM TG-43) formalism is the standard for seeds brachytherapy dose calculation. But for breast seed implants, Monte Carlo simulations reveal large errors due to tissue heterogeneity. Since TG-43 includes several factors to account for source geometry, anisotropy and strength, we propose an additional correction factor, called the inhomogeneity correction factor (ICF), accounting for tissue heterogeneity for Pd-103 brachytherapy. This correction factor is calculated as a function of the media linear attenuation coefficient and mass energy absorption coefficient, and it is independent of the source internal structure. Ultimately the dose in heterogeneous media can be calculated as a product of dose in water as calculated by TG-43 protocol times the ICF. To validate the ICF methodology, dose absorbed in spherical phantoms with large tissue heterogeneities was compared using the TG-43 formalism corrected for heterogeneity versus Monte Carlo simulations. The agreement between Monte Carlo simulations and the ICF method remained within 5% in soft tissues up to several centimeters from a Pd-103 source. Compared to Monte Carlo, the ICF methods can easily be integrated into a clinical treatment planning system and it does not require the detailed internal structure of the source or the photon phase-space.

Revision of the dosimetric parameters of the CSM11 LDR Cs-137 source.

PubMed

Otal, Antonio; Martínez-Fernández, Juan Manuel; Granero, Domingo

2011-03-01

The clinical use of brachytherapy sources requires the existence of dosimetric data with enough of quality for the proper application of treatments in clinical practice. It has been found that the published data for the low dose rate CSM11 Cs-137 source lacks of smoothness in some regions because the data are too noisy. The purpose of this study was to calculate the dosimetric data for this source in order to provide quality dosimetric improvement of the existing dosimetric data of Ballester et al . [1]. In order to obtain the dose rate distributions Monte Carlo simulations were done using the GEANT4 code. A spherical phantom 40 cm in radius with the Cs-137 source located at the centre of the phantom was used. The results from Monte Carlo simulations were applied to derive AAPM Task Group 43 dosimetric parameters: anisotropy function, radial dose function, air kerma strength and dose rate constant. The dose rate constant obtained was 1.094 ± 0.002 cGy h -1 U -1 . The new calculated data agrees within experimental uncertainties with the existing data of Ballester et al . but without the statistical noise of that study. The obtained data presently fulfills all the requirements of the TG-43U1 update and thus it can be used in clinical practice.

The use and QA of biologically related models for treatment planning: short report of the TG-166 of the therapy physics committee of the AAPM.

PubMed

Allen Li, X; Alber, Markus; Deasy, Joseph O; Jackson, Andrew; Ken Jee, Kyung-Wook; Marks, Lawrence B; Martel, Mary K; Mayo, Charles; Moiseenko, Vitali; Nahum, Alan E; Niemierko, Andrzej; Semenenko, Vladimir A; Yorke, Ellen D

2012-03-01

Treatment planning tools that use biologically related models for plan optimization and/or evaluation are being introduced for clinical use. A variety of dose-response models and quantities along with a series of organ-specific model parameters are included in these tools. However, due to various limitations, such as the limitations of models and available model parameters, the incomplete understanding of dose responses, and the inadequate clinical data, the use of biologically based treatment planning system (BBTPS) represents a paradigm shift and can be potentially dangerous. There will be a steep learning curve for most planners. The purpose of this task group is to address some of these relevant issues before the use of BBTPS becomes widely spread. In this report, the authors (1) discuss strategies, limitations, conditions, and cautions for using biologically based models and parameters in clinical treatment planning; (2) demonstrate the practical use of the three most commonly used commercially available BBTPS and potential dosimetric differences between biologically model based and dose-volume based treatment plan optimization and evaluation; (3) identify the desirable features and future directions in developing BBTPS; and (4) provide general guidelines and methodology for the acceptance testing, commissioning, and routine quality assurance (QA) of BBTPS.

SU-E-P-29: Testing Display Monitors for GSDF Compliance - a Practical Approach

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gauntt, D

2015-06-15

Purpose: To develop a simple technique for testing display monitors for compliance with the DICOM Grayscale Standard Display Function (GSDF), in accordance with the recommendations of AAPM Task Group 18. Methods: We have developed a spreadsheet that can be used to compare both the luminance response and contrast response of a display to the GSDF, using luminance measurements of the SMPTE test pattern. The contrast response compares the slope of the GSDF j-index as a function of pixel value to that of the GSDF function, and should lie within the range 0.85 to 1.15. Results: We present the results ofmore » measurements both of primary diagnostic displays and of ultrasound and acquisition workstations, all at a tertiary care hospital. The Barco displays in the radiographic reading rooms are GSDF compliant or nearly so, while those in the ultrasound reading rooms and at the acquisition workstations generally show significantly higher contrast at low luminance levels than they would if GSDF compliant, and lower contrast at high luminance levels. Conclusion: The spreadsheet that we developed allows a simple comparison of measured display contrast response to the GSDF. Although we used the SMPTE pattern, the same technique could be used with other grayscale patterns, such as TG18-QC and TG18-PQC.« less

Use of image registration and fusion algorithms and techniques in radiotherapy: Report of the AAPM Radiation Therapy Committee Task Group No. 132.

PubMed

Brock, Kristy K; Mutic, Sasa; McNutt, Todd R; Li, Hua; Kessler, Marc L

2017-07-01

Image registration and fusion algorithms exist in almost every software system that creates or uses images in radiotherapy. Most treatment planning systems support some form of image registration and fusion to allow the use of multimodality and time-series image data and even anatomical atlases to assist in target volume and normal tissue delineation. Treatment delivery systems perform registration and fusion between the planning images and the in-room images acquired during the treatment to assist patient positioning. Advanced applications are beginning to support daily dose assessment and enable adaptive radiotherapy using image registration and fusion to propagate contours and accumulate dose between image data taken over the course of therapy to provide up-to-date estimates of anatomical changes and delivered dose. This information aids in the detection of anatomical and functional changes that might elicit changes in the treatment plan or prescription. As the output of the image registration process is always used as the input of another process for planning or delivery, it is important to understand and communicate the uncertainty associated with the software in general and the result of a specific registration. Unfortunately, there is no standard mathematical formalism to perform this for real-world situations where noise, distortion, and complex anatomical variations can occur. Validation of the software systems performance is also complicated by the lack of documentation available from commercial systems leading to use of these systems in undesirable 'black-box' fashion. In view of this situation and the central role that image registration and fusion play in treatment planning and delivery, the Therapy Physics Committee of the American Association of Physicists in Medicine commissioned Task Group 132 to review current approaches and solutions for image registration (both rigid and deformable) in radiotherapy and to provide recommendations for quality assurance and quality control of these clinical processes. © 2017 American Association of Physicists in Medicine.

SU-E-T-477: An Efficient Dose Correction Algorithm Accounting for Tissue Heterogeneities in LDR Brachytherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mashouf, S; Lai, P; Karotki, A

2014-06-01

Purpose: Seed brachytherapy is currently used for adjuvant radiotherapy of early stage prostate and breast cancer patients. The current standard for calculation of dose surrounding the brachytherapy seeds is based on American Association of Physicist in Medicine Task Group No. 43 (TG-43 formalism) which generates the dose in homogeneous water medium. Recently, AAPM Task Group No. 186 emphasized the importance of accounting for tissue heterogeneities. This can be done using Monte Carlo (MC) methods, but it requires knowing the source structure and tissue atomic composition accurately. In this work we describe an efficient analytical dose inhomogeneity correction algorithm implemented usingmore » MIM Symphony treatment planning platform to calculate dose distributions in heterogeneous media. Methods: An Inhomogeneity Correction Factor (ICF) is introduced as the ratio of absorbed dose in tissue to that in water medium. ICF is a function of tissue properties and independent of source structure. The ICF is extracted using CT images and the absorbed dose in tissue can then be calculated by multiplying the dose as calculated by the TG-43 formalism times ICF. To evaluate the methodology, we compared our results with Monte Carlo simulations as well as experiments in phantoms with known density and atomic compositions. Results: The dose distributions obtained through applying ICF to TG-43 protocol agreed very well with those of Monte Carlo simulations as well as experiments in all phantoms. In all cases, the mean relative error was reduced by at least 50% when ICF correction factor was applied to the TG-43 protocol. Conclusion: We have developed a new analytical dose calculation method which enables personalized dose calculations in heterogeneous media. The advantages over stochastic methods are computational efficiency and the ease of integration into clinical setting as detailed source structure and tissue segmentation are not needed. University of Toronto, Natural Sciences and Engineering Research Council of Canada.« less

WE-G-213-02: The AAPM Award Eponyms: William D. Coolidge, Edith H. Quimby, and Marvin M.D. Williams - Who Were They and What Did They Do?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rothenberg, L.

Roentgen and the Birth of Modern Medical Physics – Perry Sprawls Wilhelm Roentgen is well known for his discovery of x-radiation. What is less known and appreciated is his intensive research following the discovery to determine the characteristics of the “new kind of radiation” and demonstrate its great value for medical purposes. In this presentation we will imagine ourselves in Roentgen’s mind and follow his thinking, including questions and doubts, as he designs and conducts a series of innovative experiments that provided the foundation for the rapid growth of medical physics. Learning Objectives: Become familiar with the personal characteristics andmore » work of Prof. Roentgen that establishes him as an inspiring model for the medical physics profession. Observe the thought process and experiments that determined and demonstrated the comprehensive characteristics of x-radiation. The AAPM Award Eponyms: William D. Coolidge, Edith H. Quimby, and Marvin M.D. Williams - Who were they and what did they do? – Lawrence N. Rothenberg William David Coolidge (1873–1975) William Coolidge was born in Hudson, NY in 1873. He obtained his BS at the Massacusetts Institute of Technology in 1896. Coolidge then went to the University of Leipzig, Germany for graduate study with physicists Paul Drude and Gustave Wiedemann and received a Ph.D. in 1899. While in Germany he met Wilhelm Roentgen. Coolidge returned to the US to teach at MIT where he was associated with Arthur A. Noyes of the Chemistry Department, working on the electrical conductivity of aqueous solutions. Willis R. Whitney, under whom Coolidge had worked before going to Germany, became head of the newly formed General Electric Research Laboratory and he invited Coolidge to work with him. In 1905, Coolidge joined the staff of the GE laboratory and was associated with it for the remainder of his life. He developed ductile tungsten filaments to replace fragile carbon filaments as the material for electric light bulb filaments. Until that innovation light bulbs had a notoriously short life. He later incorporated the ductile tungsten as a filament material for a hot cathode, fully evacuated x-ray tube, first described in 1912, which allowed higher current and x-ray output, and greater reliability than had previously been possible. These “Coolidge x-ray tubes” were far superior to the cold cathode, partial pressure gas x-ray tubes that had been in use since Roentgen’s discovery of x-rays in 1895. The Coolidge tube with incremental developments is now the key component for x-ray production in all of our modern x-ray imaging devices, such as CT scanners, interventional radiology systems, and mammography units. Coolidge was also involved in the development of sectional x-ray tubes for research and treatment that were initially designed to reach 800 kV. Additional improvements led to 1 MV and 2 MV devices. In 1932 Coolidge became director of the General Electric Research Laboratory, and in 1940, was made Vice-President and Director of Research. In 1945 he retired and was named Director Emeritus of the laboratory. Coolidge held 83 patents and was recognized for these and many other achievements by election to the National Academy of Engineers, a place in the Engineering Hall of Fame and the National Inventor’s Hall of Fame. The AAPM’s highest honor, the Coolidge Award, was named after him. He accepted Honorary Membership in the AAPM and was the first recipient of the AAPM Coolidge Award, which was presented to him in a special ceremony in Schenectady, NY in 1972 when he was 100 years old. Edith Hinckley Quimby (1891–1982) Edith Quimby was born in Rockford, IL in 1891. She graduated from Whitman College in Walla Walla, WA with a B.S. in 1913, and then obtained a masters degree from the University of California at Berkeley. Later in her career, after many significant achievements, Quimby was awarded honorary doctorates by Whitman College and Rutgers University. Edith Quimby was hired by Giacchino Failla as a radiation physicist at Memorial Hospital for Cancer in New York City. Failla had studied with Madame Curie and obtained his doctoral degree in her laboratory. After many groundbreaking medical physics studies from 1919 until 1942, they both moved to Columbia University. Dr. Quimby developed a widely employed dosimetry system for single plane implants with radium and radon seeds, and a dosimetry methodology for internal radionuclides. She was author of more than 75 scientific publications, and of significant textbooks including the first comprehensive physics textbook for radiologists “Physical Foundations of Radiology”, which was co-authored with Otto Glasser, Lauriston Taylor and James Weatherwax in the first edition, with Russell Morgan added for the second edition and Paul Goodwin for the fourth edition. With Sergei Feitelberg, M.D. she published two editions of “Radioactive Isotopes in Medicine and Biology: Basic Physics and Instrumentation”. Quimby became a renowned examiner for the American Board of Radiology when the third ABR examination, given in 1936, added physics. She served as President of the American Radium Society, received the RSNA Gold Medal, and also numerous prestigious awards given to women in science. Edith Quimby was a Charter Member of AAPM. The AAPM Lifetime Achievement Award was renamed the Edith H. Quimby Lifetime Achievement Award in her honor in 2011. Marvin Martin Dixon Williams (1902–1981) Marvin Williams was born in Walla Walla, WA in 1902, and attended the same college as Edith Quimby, graduating from Whitman College in 1926. He was greatly influenced to go into medical physics by her accomplishments. During his early career, Williams worked with James Weatherwax in Philadelphia while he was working toward an M.S. from the University of Pennsylvania. In 1931 Williams was awarded a Ph.D. in Biophysics from the University of Minnesota, with the work actually performed at the Mayo Clinic Graduate School of the University. While completing his Ph.D. studies, Marvin met Dr. Paul Hodges who had returned from the Peiping Union Medical College in Peiping (now Beijing), China. Hodges suggested that a physicist be sent to Peiping to install x-ray therapy equipment and a radon plant. Williams accepted the position and, in 1931, he and his wife Orpha left for China. Before going to China, Williams had spent time with the physics group at Memorial Hospital to learn about the operation of a radon plant. In China, he constructed the radon plant, employing 0.25 g of radium, and also installed the x-ray therapy unit. Williams and his wife returned to the US in 1935, and he accepted a research position at the Mayo Clinic. In 1950, he became Professor of Biophysics at Mayo, where he taught physics and biophysics until his retirement in 1967. Williams was also very active in the American Board of Radiology where, from 1944 through 1977, he examined over 3000 radiologists and 250 physicists. Marvin Williams was a Charter member of AAPM, served as the fourth President of AAPM in 1963, and was the fourth recipient the AAPM Coolidge Award in 1975. The Marvin Williams Award was originally established as the highest award of the American College of Medical Physics. When various functions of the ACMP were absorbed into the AAPM in 2012, the Marvin M D Williams Professional Achievement Award became one of the AAPM’s highest honors. Learning Objectives: Become familiar with the persons in whose honor the three major AAPM Award are named Learn about the achievements and activities which influenced the AAPM to name these awards in their honor.« less

WE-G-213-00: History Symposium: Radiological Physics Pioneers: Roentgen and the AAPM Award Eponyms - William Coolidge, Edith Quimby, and Marvin Williams - Who Were They and What Did They Do?

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

Roentgen and the Birth of Modern Medical Physics – Perry Sprawls Wilhelm Roentgen is well known for his discovery of x-radiation. What is less known and appreciated is his intensive research following the discovery to determine the characteristics of the “new kind of radiation” and demonstrate its great value for medical purposes. In this presentation we will imagine ourselves in Roentgen’s mind and follow his thinking, including questions and doubts, as he designs and conducts a series of innovative experiments that provided the foundation for the rapid growth of medical physics. Learning Objectives: Become familiar with the personal characteristics andmore » work of Prof. Roentgen that establishes him as an inspiring model for the medical physics profession. Observe the thought process and experiments that determined and demonstrated the comprehensive characteristics of x-radiation. The AAPM Award Eponyms: William D. Coolidge, Edith H. Quimby, and Marvin M.D. Williams - Who were they and what did they do? – Lawrence N. Rothenberg William David Coolidge (1873–1975) William Coolidge was born in Hudson, NY in 1873. He obtained his BS at the Massacusetts Institute of Technology in 1896. Coolidge then went to the University of Leipzig, Germany for graduate study with physicists Paul Drude and Gustave Wiedemann and received a Ph.D. in 1899. While in Germany he met Wilhelm Roentgen. Coolidge returned to the US to teach at MIT where he was associated with Arthur A. Noyes of the Chemistry Department, working on the electrical conductivity of aqueous solutions. Willis R. Whitney, under whom Coolidge had worked before going to Germany, became head of the newly formed General Electric Research Laboratory and he invited Coolidge to work with him. In 1905, Coolidge joined the staff of the GE laboratory and was associated with it for the remainder of his life. He developed ductile tungsten filaments to replace fragile carbon filaments as the material for electric light bulb filaments. Until that innovation light bulbs had a notoriously short life. He later incorporated the ductile tungsten as a filament material for a hot cathode, fully evacuated x-ray tube, first described in 1912, which allowed higher current and x-ray output, and greater reliability than had previously been possible. These “Coolidge x-ray tubes” were far superior to the cold cathode, partial pressure gas x-ray tubes that had been in use since Roentgen’s discovery of x-rays in 1895. The Coolidge tube with incremental developments is now the key component for x-ray production in all of our modern x-ray imaging devices, such as CT scanners, interventional radiology systems, and mammography units. Coolidge was also involved in the development of sectional x-ray tubes for research and treatment that were initially designed to reach 800 kV. Additional improvements led to 1 MV and 2 MV devices. In 1932 Coolidge became director of the General Electric Research Laboratory, and in 1940, was made Vice-President and Director of Research. In 1945 he retired and was named Director Emeritus of the laboratory. Coolidge held 83 patents and was recognized for these and many other achievements by election to the National Academy of Engineers, a place in the Engineering Hall of Fame and the National Inventor’s Hall of Fame. The AAPM’s highest honor, the Coolidge Award, was named after him. He accepted Honorary Membership in the AAPM and was the first recipient of the AAPM Coolidge Award, which was presented to him in a special ceremony in Schenectady, NY in 1972 when he was 100 years old. Edith Hinckley Quimby (1891–1982) Edith Quimby was born in Rockford, IL in 1891. She graduated from Whitman College in Walla Walla, WA with a B.S. in 1913, and then obtained a masters degree from the University of California at Berkeley. Later in her career, after many significant achievements, Quimby was awarded honorary doctorates by Whitman College and Rutgers University. Edith Quimby was hired by Giacchino Failla as a radiation physicist at Memorial Hospital for Cancer in New York City. Failla had studied with Madame Curie and obtained his doctoral degree in her laboratory. After many groundbreaking medical physics studies from 1919 until 1942, they both moved to Columbia University. Dr. Quimby developed a widely employed dosimetry system for single plane implants with radium and radon seeds, and a dosimetry methodology for internal radionuclides. She was author of more than 75 scientific publications, and of significant textbooks including the first comprehensive physics textbook for radiologists “Physical Foundations of Radiology”, which was co-authored with Otto Glasser, Lauriston Taylor and James Weatherwax in the first edition, with Russell Morgan added for the second edition and Paul Goodwin for the fourth edition. With Sergei Feitelberg, M.D. she published two editions of “Radioactive Isotopes in Medicine and Biology: Basic Physics and Instrumentation”. Quimby became a renowned examiner for the American Board of Radiology when the third ABR examination, given in 1936, added physics. She served as President of the American Radium Society, received the RSNA Gold Medal, and also numerous prestigious awards given to women in science. Edith Quimby was a Charter Member of AAPM. The AAPM Lifetime Achievement Award was renamed the Edith H. Quimby Lifetime Achievement Award in her honor in 2011. Marvin Martin Dixon Williams (1902–1981) Marvin Williams was born in Walla Walla, WA in 1902, and attended the same college as Edith Quimby, graduating from Whitman College in 1926. He was greatly influenced to go into medical physics by her accomplishments. During his early career, Williams worked with James Weatherwax in Philadelphia while he was working toward an M.S. from the University of Pennsylvania. In 1931 Williams was awarded a Ph.D. in Biophysics from the University of Minnesota, with the work actually performed at the Mayo Clinic Graduate School of the University. While completing his Ph.D. studies, Marvin met Dr. Paul Hodges who had returned from the Peiping Union Medical College in Peiping (now Beijing), China. Hodges suggested that a physicist be sent to Peiping to install x-ray therapy equipment and a radon plant. Williams accepted the position and, in 1931, he and his wife Orpha left for China. Before going to China, Williams had spent time with the physics group at Memorial Hospital to learn about the operation of a radon plant. In China, he constructed the radon plant, employing 0.25 g of radium, and also installed the x-ray therapy unit. Williams and his wife returned to the US in 1935, and he accepted a research position at the Mayo Clinic. In 1950, he became Professor of Biophysics at Mayo, where he taught physics and biophysics until his retirement in 1967. Williams was also very active in the American Board of Radiology where, from 1944 through 1977, he examined over 3000 radiologists and 250 physicists. Marvin Williams was a Charter member of AAPM, served as the fourth President of AAPM in 1963, and was the fourth recipient the AAPM Coolidge Award in 1975. The Marvin Williams Award was originally established as the highest award of the American College of Medical Physics. When various functions of the ACMP were absorbed into the AAPM in 2012, the Marvin M D Williams Professional Achievement Award became one of the AAPM’s highest honors. Learning Objectives: Become familiar with the persons in whose honor the three major AAPM Award are named Learn about the achievements and activities which influenced the AAPM to name these awards in their honor.« less

TH-EF-204-04: Experience of IMRT and Other Conformal Techniques in Russia

DOE Office of Scientific and Technical Information (OSTI.GOV)

Krylova, T.

Joanna E. Cygler, Jan Seuntjens, J. Daniel Bourland, M. Saiful Huq, Josep Puxeu Vaque, Daniel Zucca Aparicio, Tatiana Krylova, Yuri Kirpichev, Eric Ford, Caridad Borras Stereotactic Radiation Therapy (SRT) utilizes small static and dynamic (IMRT) fields, to successfully treat malignant and benign diseases using techniques such as Stereotactic Radiosurgery (SRS) and Stereotactic Body Radiation Therapy (SBRT). SRT is characterized by sharp dose gradients for individual fields and their resultant dose distributions. For appropriate targets, small field radiotherapy offers improved treatment quality by allowing better sparing of organs at risk while delivering the prescribed target dose. Specialized small field treatment deliverymore » systems, such as robotic-controlled linear accelerators, gamma radiosurgery units, and dynamic arc linear accelerators may utilize rigid fixation, image guidance, and tumor tracking, to insure precise dose delivery to static or moving targets. However, in addition to great advantages, small field delivery techniques present special technical challenges for dose calibration due to unique geometries and small field sizes not covered by existing reference dosimetry protocols such as AAPM TG-51 or IAEA TRS 398. In recent years extensive research has been performed to understand small field dosimetry and measurement instrumentation. AAPM, IAEA and ICRU task groups are expected to provide soon recommendations on the dosimetry of small radiation fields. In this symposium we will: 1] discuss the physics, instrumentation, methodologies and challenges for small field radiation dose measurements; 2] review IAEA and ICRU recommendations on prescribing, recording and reporting of small field radiation therapy; 3] discuss selected clinical applications and technical aspects for specialized image-guided, small field, linear accelerator based treatment techniques such as IMRT and SBRT. Learning Objectives: To learn the physics of small fields in contrast to dosimetry of conventional fields To learn about detectors suitable for small fields To learn about the role of Monte Carlo simulations in determination of small field output factors To provide an overview of the IAEA small field dosimetry recommendations To provide an overview of the content of the ICRU report on Prescribing, Reporting and Recording of Small Field Radiation Therapy. To learn about special technical considerations in delivering IMRT and SBRT treatments To appreciate specific challenges of IMRT implementation J. Seuntjens, Natural Sciences and Engineering Research Council; Canadian Institutes of Health Research.« less

TH-EF-204-02: Small Field Radiation Therapy: Physics and Recent Recommendations From IAEA and ICRU

DOE Office of Scientific and Technical Information (OSTI.GOV)

Seuntjens, J.

Joanna E. Cygler, Jan Seuntjens, J. Daniel Bourland, M. Saiful Huq, Josep Puxeu Vaque, Daniel Zucca Aparicio, Tatiana Krylova, Yuri Kirpichev, Eric Ford, Caridad Borras Stereotactic Radiation Therapy (SRT) utilizes small static and dynamic (IMRT) fields, to successfully treat malignant and benign diseases using techniques such as Stereotactic Radiosurgery (SRS) and Stereotactic Body Radiation Therapy (SBRT). SRT is characterized by sharp dose gradients for individual fields and their resultant dose distributions. For appropriate targets, small field radiotherapy offers improved treatment quality by allowing better sparing of organs at risk while delivering the prescribed target dose. Specialized small field treatment deliverymore » systems, such as robotic-controlled linear accelerators, gamma radiosurgery units, and dynamic arc linear accelerators may utilize rigid fixation, image guidance, and tumor tracking, to insure precise dose delivery to static or moving targets. However, in addition to great advantages, small field delivery techniques present special technical challenges for dose calibration due to unique geometries and small field sizes not covered by existing reference dosimetry protocols such as AAPM TG-51 or IAEA TRS 398. In recent years extensive research has been performed to understand small field dosimetry and measurement instrumentation. AAPM, IAEA and ICRU task groups are expected to provide soon recommendations on the dosimetry of small radiation fields. In this symposium we will: 1] discuss the physics, instrumentation, methodologies and challenges for small field radiation dose measurements; 2] review IAEA and ICRU recommendations on prescribing, recording and reporting of small field radiation therapy; 3] discuss selected clinical applications and technical aspects for specialized image-guided, small field, linear accelerator based treatment techniques such as IMRT and SBRT. Learning Objectives: To learn the physics of small fields in contrast to dosimetry of conventional fields To learn about detectors suitable for small fields To learn about the role of Monte Carlo simulations in determination of small field output factors To provide an overview of the IAEA small field dosimetry recommendations To provide an overview of the content of the ICRU report on Prescribing, Reporting and Recording of Small Field Radiation Therapy. To learn about special technical considerations in delivering IMRT and SBRT treatments To appreciate specific challenges of IMRT implementation J. Seuntjens, Natural Sciences and Engineering Research Council; Canadian Institutes of Health Research.« less

TH-EF-204-06: Closing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Borras, C.

2016-06-15

Joanna E. Cygler, Jan Seuntjens, J. Daniel Bourland, M. Saiful Huq, Josep Puxeu Vaque, Daniel Zucca Aparicio, Tatiana Krylova, Yuri Kirpichev, Eric Ford, Caridad Borras Stereotactic Radiation Therapy (SRT) utilizes small static and dynamic (IMRT) fields, to successfully treat malignant and benign diseases using techniques such as Stereotactic Radiosurgery (SRS) and Stereotactic Body Radiation Therapy (SBRT). SRT is characterized by sharp dose gradients for individual fields and their resultant dose distributions. For appropriate targets, small field radiotherapy offers improved treatment quality by allowing better sparing of organs at risk while delivering the prescribed target dose. Specialized small field treatment deliverymore » systems, such as robotic-controlled linear accelerators, gamma radiosurgery units, and dynamic arc linear accelerators may utilize rigid fixation, image guidance, and tumor tracking, to insure precise dose delivery to static or moving targets. However, in addition to great advantages, small field delivery techniques present special technical challenges for dose calibration due to unique geometries and small field sizes not covered by existing reference dosimetry protocols such as AAPM TG-51 or IAEA TRS 398. In recent years extensive research has been performed to understand small field dosimetry and measurement instrumentation. AAPM, IAEA and ICRU task groups are expected to provide soon recommendations on the dosimetry of small radiation fields. In this symposium we will: 1] discuss the physics, instrumentation, methodologies and challenges for small field radiation dose measurements; 2] review IAEA and ICRU recommendations on prescribing, recording and reporting of small field radiation therapy; 3] discuss selected clinical applications and technical aspects for specialized image-guided, small field, linear accelerator based treatment techniques such as IMRT and SBRT. Learning Objectives: To learn the physics of small fields in contrast to dosimetry of conventional fields To learn about detectors suitable for small fields To learn about the role of Monte Carlo simulations in determination of small field output factors To provide an overview of the IAEA small field dosimetry recommendations To provide an overview of the content of the ICRU report on Prescribing, Reporting and Recording of Small Field Radiation Therapy. To learn about special technical considerations in delivering IMRT and SBRT treatments To appreciate specific challenges of IMRT implementation J. Seuntjens, Natural Sciences and Engineering Research Council; Canadian Institutes of Health Research.« less

TH-EF-204-01: Introduction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cygler, J.

2016-06-15

Joanna E. Cygler, Jan Seuntjens, J. Daniel Bourland, M. Saiful Huq, Josep Puxeu Vaque, Daniel Zucca Aparicio, Tatiana Krylova, Yuri Kirpichev, Eric Ford, Caridad Borras Stereotactic Radiation Therapy (SRT) utilizes small static and dynamic (IMRT) fields, to successfully treat malignant and benign diseases using techniques such as Stereotactic Radiosurgery (SRS) and Stereotactic Body Radiation Therapy (SBRT). SRT is characterized by sharp dose gradients for individual fields and their resultant dose distributions. For appropriate targets, small field radiotherapy offers improved treatment quality by allowing better sparing of organs at risk while delivering the prescribed target dose. Specialized small field treatment deliverymore » systems, such as robotic-controlled linear accelerators, gamma radiosurgery units, and dynamic arc linear accelerators may utilize rigid fixation, image guidance, and tumor tracking, to insure precise dose delivery to static or moving targets. However, in addition to great advantages, small field delivery techniques present special technical challenges for dose calibration due to unique geometries and small field sizes not covered by existing reference dosimetry protocols such as AAPM TG-51 or IAEA TRS 398. In recent years extensive research has been performed to understand small field dosimetry and measurement instrumentation. AAPM, IAEA and ICRU task groups are expected to provide soon recommendations on the dosimetry of small radiation fields. In this symposium we will: 1] discuss the physics, instrumentation, methodologies and challenges for small field radiation dose measurements; 2] review IAEA and ICRU recommendations on prescribing, recording and reporting of small field radiation therapy; 3] discuss selected clinical applications and technical aspects for specialized image-guided, small field, linear accelerator based treatment techniques such as IMRT and SBRT. Learning Objectives: To learn the physics of small fields in contrast to dosimetry of conventional fields To learn about detectors suitable for small fields To learn about the role of Monte Carlo simulations in determination of small field output factors To provide an overview of the IAEA small field dosimetry recommendations To provide an overview of the content of the ICRU report on Prescribing, Reporting and Recording of Small Field Radiation Therapy. To learn about special technical considerations in delivering IMRT and SBRT treatments To appreciate specific challenges of IMRT implementation J. Seuntjens, Natural Sciences and Engineering Research Council; Canadian Institutes of Health Research.« less

TH-EF-204-03: Determination of Small Field Output Factors, Advantages and Limitations of Monte Carlo Simulation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vaque, J. Puxeu

2016-06-15

Joanna E. Cygler, Jan Seuntjens, J. Daniel Bourland, M. Saiful Huq, Josep Puxeu Vaque, Daniel Zucca Aparicio, Tatiana Krylova, Yuri Kirpichev, Eric Ford, Caridad Borras Stereotactic Radiation Therapy (SRT) utilizes small static and dynamic (IMRT) fields, to successfully treat malignant and benign diseases using techniques such as Stereotactic Radiosurgery (SRS) and Stereotactic Body Radiation Therapy (SBRT). SRT is characterized by sharp dose gradients for individual fields and their resultant dose distributions. For appropriate targets, small field radiotherapy offers improved treatment quality by allowing better sparing of organs at risk while delivering the prescribed target dose. Specialized small field treatment deliverymore » systems, such as robotic-controlled linear accelerators, gamma radiosurgery units, and dynamic arc linear accelerators may utilize rigid fixation, image guidance, and tumor tracking, to insure precise dose delivery to static or moving targets. However, in addition to great advantages, small field delivery techniques present special technical challenges for dose calibration due to unique geometries and small field sizes not covered by existing reference dosimetry protocols such as AAPM TG-51 or IAEA TRS 398. In recent years extensive research has been performed to understand small field dosimetry and measurement instrumentation. AAPM, IAEA and ICRU task groups are expected to provide soon recommendations on the dosimetry of small radiation fields. In this symposium we will: 1] discuss the physics, instrumentation, methodologies and challenges for small field radiation dose measurements; 2] review IAEA and ICRU recommendations on prescribing, recording and reporting of small field radiation therapy; 3] discuss selected clinical applications and technical aspects for specialized image-guided, small field, linear accelerator based treatment techniques such as IMRT and SBRT. Learning Objectives: To learn the physics of small fields in contrast to dosimetry of conventional fields To learn about detectors suitable for small fields To learn about the role of Monte Carlo simulations in determination of small field output factors To provide an overview of the IAEA small field dosimetry recommendations To provide an overview of the content of the ICRU report on Prescribing, Reporting and Recording of Small Field Radiation Therapy. To learn about special technical considerations in delivering IMRT and SBRT treatments To appreciate specific challenges of IMRT implementation J. Seuntjens, Natural Sciences and Engineering Research Council; Canadian Institutes of Health Research.« less

TH-EF-204-05: Application of Small-Field Treatment: The Promises and Pitfalls of SBRT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ford, E.

2016-06-15

Joanna E. Cygler, Jan Seuntjens, J. Daniel Bourland, M. Saiful Huq, Josep Puxeu Vaque, Daniel Zucca Aparicio, Tatiana Krylova, Yuri Kirpichev, Eric Ford, Caridad Borras Stereotactic Radiation Therapy (SRT) utilizes small static and dynamic (IMRT) fields, to successfully treat malignant and benign diseases using techniques such as Stereotactic Radiosurgery (SRS) and Stereotactic Body Radiation Therapy (SBRT). SRT is characterized by sharp dose gradients for individual fields and their resultant dose distributions. For appropriate targets, small field radiotherapy offers improved treatment quality by allowing better sparing of organs at risk while delivering the prescribed target dose. Specialized small field treatment deliverymore » systems, such as robotic-controlled linear accelerators, gamma radiosurgery units, and dynamic arc linear accelerators may utilize rigid fixation, image guidance, and tumor tracking, to insure precise dose delivery to static or moving targets. However, in addition to great advantages, small field delivery techniques present special technical challenges for dose calibration due to unique geometries and small field sizes not covered by existing reference dosimetry protocols such as AAPM TG-51 or IAEA TRS 398. In recent years extensive research has been performed to understand small field dosimetry and measurement instrumentation. AAPM, IAEA and ICRU task groups are expected to provide soon recommendations on the dosimetry of small radiation fields. In this symposium we will: 1] discuss the physics, instrumentation, methodologies and challenges for small field radiation dose measurements; 2] review IAEA and ICRU recommendations on prescribing, recording and reporting of small field radiation therapy; 3] discuss selected clinical applications and technical aspects for specialized image-guided, small field, linear accelerator based treatment techniques such as IMRT and SBRT. Learning Objectives: To learn the physics of small fields in contrast to dosimetry of conventional fields To learn about detectors suitable for small fields To learn about the role of Monte Carlo simulations in determination of small field output factors To provide an overview of the IAEA small field dosimetry recommendations To provide an overview of the content of the ICRU report on Prescribing, Reporting and Recording of Small Field Radiation Therapy. To learn about special technical considerations in delivering IMRT and SBRT treatments To appreciate specific challenges of IMRT implementation J. Seuntjens, Natural Sciences and Engineering Research Council; Canadian Institutes of Health Research.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mahesh, M; Borras, C; Frey, G

This workshop is jointly organized by the AAPM, the Spanish (SEFM) and the Russian (AMPR) Medical Physics Societies, as part of formal educational exchange agreements signed by the AAPM with each one of these two societies.With the rapid technological advances in radiation therapy both for treatment and imaging, it is challenging how physics is taught to medical physicists practicing in radiation therapy. The main Objectives: of this workshop is to bring forth current status, challenges and issues related to education of radiation therapy physicists here in the US, Spain and Russia. Medical physicists from each one of these countries willmore » present educational requirements of international recommendations and directives and analyze their impact on national legislations. Current and future educational models and plans for harmonization will be described. The role of universities, professional societies and examination boards, such as the American Board of Radiology, will be discussed. Minimum standards will be agreed upon. Learning Objectives: Review medical physics educational models supported by AAPM, SEFM, and AMPR. Discuss the role of governmental and non-governmental organizations in elaborating and adopting medical physics syllabi. Debate minimum educational standards for medical physics education based on country-specific resources.« less

Anniversary paper: evolution of ultrasound physics and the role of medical physicists and the AAPM and its journal in that evolution.

PubMed

Carson, Paul L; Fenster, Aaron

2009-02-01

Ultrasound has been the greatest imaging modality worldwide for many years by equipment purchase value and by number of machines and examinations. It is becoming increasingly the front end imaging modality; serving often as an extension of the physician's fingers. We believe that at the other extreme, high-end systems will continue to compete with all other imaging modalities in imaging departments to be the method of choice for various applications, particularly where safety and cost are paramount. Therapeutic ultrasound, in addition to the physiotherapy practiced for many decades, is just coming into its own as a major tool in the long progression to less invasive interventional treatment. The physics of medical ultrasound has evolved over many fronts throughout its history. For this reason, a topical review, rather than a primarily chronological one is presented. A brief review of medical ultrasound imaging and therapy is presented, with an emphasis on the contributions of medical physicists, the American Association of Physicists in Medicine (AAPM) and its publications, particularly its journal Medical Physics. The AAPM and Medical Physics have contributed substantially to training of physicists and engineers, medical practitioners, technologists, and the public.

Monte Carlo reference data sets for imaging research: Executive summary of the report of AAPM Research Committee Task Group 195.

PubMed

Sechopoulos, Ioannis; Ali, Elsayed S M; Badal, Andreu; Badano, Aldo; Boone, John M; Kyprianou, Iacovos S; Mainegra-Hing, Ernesto; McMillan, Kyle L; McNitt-Gray, Michael F; Rogers, D W O; Samei, Ehsan; Turner, Adam C

2015-10-01

The use of Monte Carlo simulations in diagnostic medical imaging research is widespread due to its flexibility and ability to estimate quantities that are challenging to measure empirically. However, any new Monte Carlo simulation code needs to be validated before it can be used reliably. The type and degree of validation required depends on the goals of the research project, but, typically, such validation involves either comparison of simulation results to physical measurements or to previously published results obtained with established Monte Carlo codes. The former is complicated due to nuances of experimental conditions and uncertainty, while the latter is challenging due to typical graphical presentation and lack of simulation details in previous publications. In addition, entering the field of Monte Carlo simulations in general involves a steep learning curve. It is not a simple task to learn how to program and interpret a Monte Carlo simulation, even when using one of the publicly available code packages. This Task Group report provides a common reference for benchmarking Monte Carlo simulations across a range of Monte Carlo codes and simulation scenarios. In the report, all simulation conditions are provided for six different Monte Carlo simulation cases that involve common x-ray based imaging research areas. The results obtained for the six cases using four publicly available Monte Carlo software packages are included in tabular form. In addition to a full description of all simulation conditions and results, a discussion and comparison of results among the Monte Carlo packages and the lessons learned during the compilation of these results are included. This abridged version of the report includes only an introductory description of the six cases and a brief example of the results of one of the cases. This work provides an investigator the necessary information to benchmark his/her Monte Carlo simulation software against the reference cases included here before performing his/her own novel research. In addition, an investigator entering the field of Monte Carlo simulations can use these descriptions and results as a self-teaching tool to ensure that he/she is able to perform a specific simulation correctly. Finally, educators can assign these cases as learning projects as part of course objectives or training programs.

I-125 seed calibration using the SeedSelectron® afterloader: a practical solution to fulfill AAPM-ESTRO recommendations

PubMed Central

Perez-Calatayud, Jose; Richart, Jose; Guirado, Damián; Pérez-García, Jordi; Rodríguez, Silvia; Santos, Manuel

2012-01-01

Purpose SeedSelectron® v1.26b (Nucletron BV, The Netherlands) is an afterloader system used in prostate interstitial permanent brachytherapy with I-125 selectSeed seeds. It contains a diode array to assay all implanted seeds. Only one or two seeds can be extracted during the surgical procedure and assayed using a well chamber to check the manufacturer air-kerma strength (SK) and to calibrate the diode array. Therefore, it is not feasible to assay 5–10% seeds as required by the AAPM-ESTRO. In this study, we present a practical solution of the SeedSelectron® users to fulfill the AAPM- ESTRO recommendations. Material and methods The method is based on: a) the SourceCheck® well ionization chamber (PTW, Germany) provided with a PTW insert; b) n = 10 selectSeed from the same batch and class as the seeds for the implant; c) the Nucletron insert to accommodate the n = 10 seeds on the SourceCheck® and to measure their averaged SK. Results for 56 implants have been studied comparing the SK value from the manufacturer with the one obtained with the n = 10 seeds using the Nucletron insert prior to the implant and with the SK of just one seed measured with the PTW insert during the implant. Results We are faced with SK deviation for individual seeds up to 7.8%. However, in the majority of cases SK is in agreement with the manufacturer value. With the method proposed using the Nucletron insert, the large deviations of SK are reduced and for 56 implants studied no deviation outside the range of the class were found. Conclusions The new Nucletron insert and the proposed procedure allow to evaluate the SK of the n = 10 seeds prior to the implant, fulfilling the AAPM-ESTRO recommendations. It has been adopted by Nucletron to be extended to seedSelectron® users under request. PMID:23346136

MO-F-16A-03: AAPM Online Learning Support of New ABR MOC Requirements

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bloch, C; Ogburn, J; Woodward, M

2014-06-15

In 2002 the American Board of Radiology (ABR) discontinued issuing lifetime board certification. After that time diplomates received a timelimited certificate and must participate in the Maintenance of Certification (MOC) program in order to maintain their certification. Initially certificates were issued with a 10 year expiration period and the MOC had requirements to be met over that 10 year period. The goal was to demonstrate continuous maintenance of clinical competency, however some diplomates were attempting to fulfill most or all of the requirements near the end of the 10 year period. This failed to meet the continuous aspect of themore » goal and so the ABR changed to a sliding 3-year window. This was done to recognize that not every year would be the same, but that diplomates should be able to maintain a reasonable average over any 3 year period.A second significant change occurred in 2013. The initial requirements included 20 selfassessment modules (SAMs) over the original 10 year term. SAMs are a special type of continuing education (CE) credit that were an addition to the 250 standard CE credits required over the 10 year period. In 2013, however, the new requirement is 75 CE credits over the previous 3 years, of which 25 must include self-assessment. Effectively this raised the self-assessment requirement from 20 in 10 years to 25 in 3 years. Previously SAMs were an interactive presentation available in limited quantities at live meetings. However, the new requirement is not for SAMs but CE-SA which includes SAMs, but also includes the online quizzes provided at the AAPM online learning center. All credits earned at the AAPM online learning center fulfill the ABR SA requirement.This talk will be an interactive demonstration of the AAPM online learning center along with a discussion of the MOC requirements.« less

SU-F-T-54: Determination of the AAPM TG-43 Brachytherapy Dosimetry Parameters for A New Titanium-Encapsulated Yb-169 Source by Monte Carlo Calculations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reynoso, F; Washington University School of Medicine, St. Louis, MO; Munro, J

2016-06-15

Purpose: To determine the AAPM TG-43 brachytherapy dosimetry parameters of a new titanium-encapsulated Yb-169 source designed to maximize the dose enhancement during gold nanoparticle-aided radiation therapy (GNRT). Methods: An existing Monte Carlo (MC) model of the titanium-encapsulated Yb-169 source, which was described in the current investigators’ published MC optimization study, was modified based on the source manufacturer’s detailed specifications, resulting in an accurate model of the titanium-encapsulated Yb-169 source that was actually manufactured. MC calculations were then performed using the MCNP5 code system and the modified source model, in order to obtain a complete set of the AAPM TG-43 parametersmore » for the new Yb-169 source. Results: The MC-calculated dose rate constant for the new titanium-encapsulated Yb-169 source was 1.05 ± 0.03 cGy per hr U, indicating about 10% decrease from the values reported for the conventional stainless steel-encapsulated Yb-169 sources. The source anisotropy and radial dose function for the new source were found similar to those reported for the conventional Yb-169 sources. Conclusion: In this study, the AAPM TG-43 brachytherapy dosimetry parameters of a new titanium-encapsulated Yb-169 source were determined by MC calculations. The current results suggested that the use of titanium, instead of stainless steel, to encapsulate the Yb-169 core would not lead to any major change in the dosimetric characteristics of the Yb-169 source, while it would allow more low energy photons being transmitted through the source filter thereby leading to an increased dose enhancement during GNRT. Supported by DOD/PCRP grant W81XWH-12-1-0198 This investigation was supported by DOD/PCRP grant W81XWH-12-1- 0198.« less

WE-AB-213-03: Challenges and Opportunities

DOE Office of Scientific and Technical Information (OSTI.GOV)

Borras, C.

AAPM projects and collaborations in Africa Adam Shulman (AA-SC Chair) The African Affairs Subcommittee (AA-SC) of the AAPM will present a multi-institutional approach to medical physics support in Africa. Current work to increase the quality of care and level of safety for the medical physics practice in Senegal, Ghana, and Zimbabwe will be presented, along with preliminary projects in Nigeria and Botswana. Because the task of addressing the needs of medical physics in countries across Africa is larger than one entity can accomplish on its own, the AA-SC has taken the approach of joining forces with multiple organizations such asmore » Radiating Hope and TreatSafely (NGO’s), the IAEA, companies like BrainLab, Varian and Elekta, medical volunteers and academic institutions such as NYU and Washington University. Elements of current projects include: 1) Distance training and evaluation of the quality of contouring and treatment planning, teaching treatment planning and other subjects, and troubleshooting using modern telecommunications technology in Senegal, Ghana, and Zimbabwe; 2) Assistance in the transition from 2D to 3D in Senegal and Zimbabwe; 3) Assistance in the transition from 3D to IMRT using in-house compensators in Senegal; 4) Modernizing the cancer center in Senegal and increasing safety and; 5) Training on on 3D techniques in Ghana; 6) Assisting a teaching and training radiation oncology center to be built in Zimbabwe; 7) Working with the ISEP Program in Sub-Saharan Africa; 8) Creating instructional videos on linac commissioning; 9) Working on a possible collaboration to train physicists in Nigeria. Building on past achievements, the subcommittee seeks to make a larger impact on the continent, as the number and size of projects increases and more human resources become available. The State of Medical Physics Collaborations and Projects in Latin America Sandra Guzman (Peru) The lack of Medical Physicists (MP) in many Latin American (LA) countries leads to recruitment of professionals with incomplete education. In most LA countries only one MP responsible for each Center is currently mandated. Currently there is a large disparity among MP training programs and there is significant debate about the standards of MP graduate education in many LA countries. There are no commonly recognized academic programs, not enough clinical training sites and clinical training is not typically considered as part of the MP work. Economic pressures and high workloads also impede the creation of more training centers. The increasing need of qualified MPs require establishing a coordinated system of national Education & Training Centers (ETC), to meet the international standards of education and training in Medical Physics. This shortfall calls for support of organizations such as the IOMP, AAPM, ALFIM, IAEA, etc. Examples from various LA countries, as well as some proposed solutions, will be presented. In particular, we will discuss the resources that the AAPM and its members can offer to support regional programs. The ‘Medical Imaging’ physicist in the emerging world: Challenges and opportunities - Caridad Borrás (WGNIMP Chair) While the role of radiation therapy physicists in the emerging world is reasonably well established, the role of medical imaging physicists is not. The only perceived needs in radiology departments are equipment quality control and radiation protection, tasks that can be done by a technologist or a service engineer. To change the situation, the International Basic Safety Standard, which is adopted/adapted world-wide as national radiation protection regulations, states: “For diagnostic radiological procedures and image guided interventional procedures, the requirements of these Standards for medical imaging, calibration, dosimetry and quality assurance, including the acceptance and commissioning of medical radiological equipment, are fulfilled by or under the oversight of, or with the documented advice of a medical physicist, whose degree of involvement is determined by the complexity of the radiological procedures and the associated radiation risks”. Details on how these requirements can be carried out in resource-limited settings will be described. IAEA support to medical physics in Africa and Latin America: achievements and challenges Ahmed Meghzifene (IAEA) Shortage of clinically qualified medical physicists in radiotherapy and imaging, insufficient and inadequate education and training programs, as well as a lack of professional recognition were identified as the main issues to be addressed by the IAEA. The IAEA developed a series of integrated projects aiming specifically at promoting the essential role of medical physicists in health care, developing harmonized guidelines on dosimetry and quality assurance, and supporting education and clinical training programs. The unique feature of the IAEA approach is support it provides for implementation of guidelines and education programs in Member States through its technical cooperation project. The presentation will summarize IAEA support to Latin America and Africa in the field of medical physics and will highlight how the new International Basic Safety Standards are expected to impact the medical physics practice in low and middle income countries. Learning Objectives: Learn about the shortage of qualified Medical Physicists in Africa and Latin America. Understand the reasons of this shortage. Learn about the ways to improve the situation and AAPM role in this process.« less

WE-AB-213-05: Closing Remarks

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pipman, Y.

AAPM projects and collaborations in Africa Adam Shulman (AA-SC Chair) The African Affairs Subcommittee (AA-SC) of the AAPM will present a multi-institutional approach to medical physics support in Africa. Current work to increase the quality of care and level of safety for the medical physics practice in Senegal, Ghana, and Zimbabwe will be presented, along with preliminary projects in Nigeria and Botswana. Because the task of addressing the needs of medical physics in countries across Africa is larger than one entity can accomplish on its own, the AA-SC has taken the approach of joining forces with multiple organizations such asmore » Radiating Hope and TreatSafely (NGO’s), the IAEA, companies like BrainLab, Varian and Elekta, medical volunteers and academic institutions such as NYU and Washington University. Elements of current projects include: 1) Distance training and evaluation of the quality of contouring and treatment planning, teaching treatment planning and other subjects, and troubleshooting using modern telecommunications technology in Senegal, Ghana, and Zimbabwe; 2) Assistance in the transition from 2D to 3D in Senegal and Zimbabwe; 3) Assistance in the transition from 3D to IMRT using in-house compensators in Senegal; 4) Modernizing the cancer center in Senegal and increasing safety and; 5) Training on on 3D techniques in Ghana; 6) Assisting a teaching and training radiation oncology center to be built in Zimbabwe; 7) Working with the ISEP Program in Sub-Saharan Africa; 8) Creating instructional videos on linac commissioning; 9) Working on a possible collaboration to train physicists in Nigeria. Building on past achievements, the subcommittee seeks to make a larger impact on the continent, as the number and size of projects increases and more human resources become available. The State of Medical Physics Collaborations and Projects in Latin America Sandra Guzman (Peru) The lack of Medical Physicists (MP) in many Latin American (LA) countries leads to recruitment of professionals with incomplete education. In most LA countries only one MP responsible for each Center is currently mandated. Currently there is a large disparity among MP training programs and there is significant debate about the standards of MP graduate education in many LA countries. There are no commonly recognized academic programs, not enough clinical training sites and clinical training is not typically considered as part of the MP work. Economic pressures and high workloads also impede the creation of more training centers. The increasing need of qualified MPs require establishing a coordinated system of national Education & Training Centers (ETC), to meet the international standards of education and training in Medical Physics. This shortfall calls for support of organizations such as the IOMP, AAPM, ALFIM, IAEA, etc. Examples from various LA countries, as well as some proposed solutions, will be presented. In particular, we will discuss the resources that the AAPM and its members can offer to support regional programs. The ‘Medical Imaging’ physicist in the emerging world: Challenges and opportunities - Caridad Borrás (WGNIMP Chair) While the role of radiation therapy physicists in the emerging world is reasonably well established, the role of medical imaging physicists is not. The only perceived needs in radiology departments are equipment quality control and radiation protection, tasks that can be done by a technologist or a service engineer. To change the situation, the International Basic Safety Standard, which is adopted/adapted world-wide as national radiation protection regulations, states: “For diagnostic radiological procedures and image guided interventional procedures, the requirements of these Standards for medical imaging, calibration, dosimetry and quality assurance, including the acceptance and commissioning of medical radiological equipment, are fulfilled by or under the oversight of, or with the documented advice of a medical physicist, whose degree of involvement is determined by the complexity of the radiological procedures and the associated radiation risks”. Details on how these requirements can be carried out in resource-limited settings will be described. IAEA support to medical physics in Africa and Latin America: achievements and challenges Ahmed Meghzifene (IAEA) Shortage of clinically qualified medical physicists in radiotherapy and imaging, insufficient and inadequate education and training programs, as well as a lack of professional recognition were identified as the main issues to be addressed by the IAEA. The IAEA developed a series of integrated projects aiming specifically at promoting the essential role of medical physicists in health care, developing harmonized guidelines on dosimetry and quality assurance, and supporting education and clinical training programs. The unique feature of the IAEA approach is support it provides for implementation of guidelines and education programs in Member States through its technical cooperation project. The presentation will summarize IAEA support to Latin America and Africa in the field of medical physics and will highlight how the new International Basic Safety Standards are expected to impact the medical physics practice in low and middle income countries. Learning Objectives: Learn about the shortage of qualified Medical Physicists in Africa and Latin America. Understand the reasons of this shortage. Learn about the ways to improve the situation and AAPM role in this process.« less

Evidence for a blockwise distribution of acetyl groups onto homogalacturonans from a commercial sugar beet (Beta vulgaris) pectin.

PubMed

Ralet, Marie-Christine; Crépeau, Marie-Jeanne; Bonnin, Estelle

2008-06-01

Commercial acid-extracted sugar beet pectin was extensively hydrolysed using an endo-polygalacturonase (AnPGI from Aspergillus niger or AnPGII from A. niger or FmPG from Fusarium moniliforme) in combination with Aspergillus aculeatus pectin methyl-esterase (AaPME). The homogalacturonan-derived oligogalacturonates released were quantified by high-performance anion-exchange chromatography and their structure determined by mass spectrometry. The different endo-polygalacturonases exhibited variable tolerance towards acetyl groups. AnPGI was the most active and FmPG the less. A hypothetical homogalacturonan was constructed using the AnPGI-recovered oligogalacturonates as building blocks and the validity of the model was checked taking into account FmPG observed requirements and hydrolysis products. A blockwise repartition of the acetyl groups onto sugar beet pectin homogalacturonan is proposed.

CT dose equilibration and energy absorption in polyethylene cylinders with diameters from 6 to 55 cm

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Xinhua; Zhang, Da; Liu, Bob, E-mail: bliu7@mgh.harvard.edu

2015-06-15

Purpose: ICRU Report No. 87 Committee and AAPM Task Group 200 designed a three-sectional polyethylene phantom of 30 cm in diameter and 60 cm in length for evaluating the midpoint dose D{sub L}(0) and its rise-to-the-equilibrium curve H(L) = D{sub L}(0)/D{sub eq} from computed tomography (CT) scanning, where D{sub eq} is the equilibrium dose. To aid the use of the phantom in radiation dose assessment and to gain an understanding of dose equilibration and energy absorption in polyethylene, the authors evaluated the short (20 cm) to long (60 cm) phantom dose ratio with a polyethylene diameter of 30 cm, assessedmore » H(L) in polyethylene cylinders of 6–55 cm in diameters, and examined energy absorption in these cylinders. Methods: A GEANT4-based Monte Carlo program was used to simulate the single axial scans of polyethylene cylinders (diameters 6–55 cm and length 90 cm, as well as diameter 30 cm and lengths 20 and 60 cm) on a clinical CT scanner (Somatom Definition dual source CT, Siemens Healthcare). Axial dose distributions were computed on the phantom central and peripheral axes. An average dose over the central 23 or 100 mm region was evaluated for modeling dose measurement using a 0.6 cm{sup 3} thimble chamber or a 10 cm long pencil ion chamber, respectively. The short (20 cm) to long (90 cm) phantom dose ratios were calculated for the 30 cm diameter polyethylene phantoms scanned at four tube voltages (80–140 kV) and a range of beam apertures (1–25 cm). H(L) was evaluated using the dose integrals computed with the 90 cm long phantoms. The resultant H(L) data were subsequently used to compute the fraction of the total energy absorbed inside or outside the scan range (E{sub in}/E or E{sub out}/E) on the phantom central and peripheral axes, where E = LD{sub eq} was the total energy absorbed along the z axis. Results: The midpoint dose in the 60 cm long polyethylene phantom was equal to that in the 90 cm long polyethylene phantom. The short-to-long phantom dose ratios changed with beam aperture and phantom axis but were insensitive to tube voltage. H(L) was insensitive to tube voltage and CT scanner model. As phantom diameter increased from 6 to 55 cm, E{sub in}/E generally decreased but asymptotically approached constant levels on the peripheral axes of large phantoms. The curve of E{sub in}/E versus scan length was almost identical to that of H(L). Similarly, E{sub out}/E increased with scan length and asymptotically approached the equilibrium for large scan lengths. E{sub out}/D{sub eq} was much less than the equilibrium length L{sub eq} where H(L) = 0.98, even with scan lengths much larger than L{sub eq}. Conclusions: The polyethylene phantom designed by ICRU Report No. 87 Committee and AAPM Task Group 200 is adequately long for assessing the midpoint dose and its equilibration in CT scanning. The short-to-long phantom dose ratios and the H(L) data provided in this paper allow easy evaluations of the midpoint dose, longitudinal dose distribution, and energy absorption in polyethylene phantoms. The results of dose equilibration and energy absorption presented herein may be insightful for the clinical CT scans with various subject sizes and scan lengths.« less

Postdoctoral Opportunities in Medical Physics

NASA Astrophysics Data System (ADS)

Hogstrom, Kenneth

2006-04-01

The medical physicist is a professional who specializes in the application of the concepts and methods of physics to the diagnosis and treatment of human disease. Medical physicists identify their primary discipline to be radiation therapy (78%), medical imaging (16%), nuclear medicine (3%), or radiation safety (2%). They state their primary responsibility to be clinical (78%), academic (9%), research (4%), etc. Correspondingly, medical physicists reveal their primarily employment to be a private hospital (42%), university hospital (32%), physicist's service group (9%), physician's service group (9%), industry (5%), and government (3%). The most frequent job of medical physicists is clinical radiation therapy physicist, whose clinical duties include: equipment acquisition, facility design, commissioning, machine maintenance, calibration and quality assurance, patient treatment planning, patient dose calculation, management of patient procedures, development of new technology, radiation safety, and regulatory compliance. The number of medical physicists in the United States can be estimated by the number of members of the American Association of Physicists in Medicine (AAPM), which has increased 5.5% annually since 1969, currently being 5,000. New positions plus retirements create a current need >300 new medical physicists per year, which exceeds supply. This is supported by the steady growth in average salaries, being 100,000 for PhDs entering the field and reaching 180,000. Graduate programs alone cannot meet demand, and physicists entering the field through postdoctoral training in medical physics remain important. Details of postdoctoral research programs and medical physics residency programs will provide direction to physics PhD graduates interested in medical physics. [The AAPM, its annual Professional Information Report, and its Public Education Committee are acknowledged for information contributing to this presentation.

WE-G-213-01: Roentgen and the Birth of Modern Medical Physics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sprawls, P.

Roentgen and the Birth of Modern Medical Physics – Perry Sprawls Wilhelm Roentgen is well known for his discovery of x-radiation. What is less known and appreciated is his intensive research following the discovery to determine the characteristics of the “new kind of radiation” and demonstrate its great value for medical purposes. In this presentation we will imagine ourselves in Roentgen’s mind and follow his thinking, including questions and doubts, as he designs and conducts a series of innovative experiments that provided the foundation for the rapid growth of medical physics. Learning Objectives: Become familiar with the personal characteristics andmore » work of Prof. Roentgen that establishes him as an inspiring model for the medical physics profession. Observe the thought process and experiments that determined and demonstrated the comprehensive characteristics of x-radiation. The AAPM Award Eponyms: William D. Coolidge, Edith H. Quimby, and Marvin M.D. Williams - Who were they and what did they do? – Lawrence N. Rothenberg William David Coolidge (1873–1975) William Coolidge was born in Hudson, NY in 1873. He obtained his BS at the Massacusetts Institute of Technology in 1896. Coolidge then went to the University of Leipzig, Germany for graduate study with physicists Paul Drude and Gustave Wiedemann and received a Ph.D. in 1899. While in Germany he met Wilhelm Roentgen. Coolidge returned to the US to teach at MIT where he was associated with Arthur A. Noyes of the Chemistry Department, working on the electrical conductivity of aqueous solutions. Willis R. Whitney, under whom Coolidge had worked before going to Germany, became head of the newly formed General Electric Research Laboratory and he invited Coolidge to work with him. In 1905, Coolidge joined the staff of the GE laboratory and was associated with it for the remainder of his life. He developed ductile tungsten filaments to replace fragile carbon filaments as the material for electric light bulb filaments. Until that innovation light bulbs had a notoriously short life. He later incorporated the ductile tungsten as a filament material for a hot cathode, fully evacuated x-ray tube, first described in 1912, which allowed higher current and x-ray output, and greater reliability than had previously been possible. These “Coolidge x-ray tubes” were far superior to the cold cathode, partial pressure gas x-ray tubes that had been in use since Roentgen’s discovery of x-rays in 1895. The Coolidge tube with incremental developments is now the key component for x-ray production in all of our modern x-ray imaging devices, such as CT scanners, interventional radiology systems, and mammography units. Coolidge was also involved in the development of sectional x-ray tubes for research and treatment that were initially designed to reach 800 kV. Additional improvements led to 1 MV and 2 MV devices. In 1932 Coolidge became director of the General Electric Research Laboratory, and in 1940, was made Vice-President and Director of Research. In 1945 he retired and was named Director Emeritus of the laboratory. Coolidge held 83 patents and was recognized for these and many other achievements by election to the National Academy of Engineers, a place in the Engineering Hall of Fame and the National Inventor’s Hall of Fame. The AAPM’s highest honor, the Coolidge Award, was named after him. He accepted Honorary Membership in the AAPM and was the first recipient of the AAPM Coolidge Award, which was presented to him in a special ceremony in Schenectady, NY in 1972 when he was 100 years old. Edith Hinckley Quimby (1891–1982) Edith Quimby was born in Rockford, IL in 1891. She graduated from Whitman College in Walla Walla, WA with a B.S. in 1913, and then obtained a masters degree from the University of California at Berkeley. Later in her career, after many significant achievements, Quimby was awarded honorary doctorates by Whitman College and Rutgers University. Edith Quimby was hired by Giacchino Failla as a radiation physicist at Memorial Hospital for Cancer in New York City. Failla had studied with Madame Curie and obtained his doctoral degree in her laboratory. After many groundbreaking medical physics studies from 1919 until 1942, they both moved to Columbia University. Dr. Quimby developed a widely employed dosimetry system for single plane implants with radium and radon seeds, and a dosimetry methodology for internal radionuclides. She was author of more than 75 scientific publications, and of significant textbooks including the first comprehensive physics textbook for radiologists “Physical Foundations of Radiology”, which was co-authored with Otto Glasser, Lauriston Taylor and James Weatherwax in the first edition, with Russell Morgan added for the second edition and Paul Goodwin for the fourth edition. With Sergei Feitelberg, M.D. she published two editions of “Radioactive Isotopes in Medicine and Biology: Basic Physics and Instrumentation”. Quimby became a renowned examiner for the American Board of Radiology when the third ABR examination, given in 1936, added physics. She served as President of the American Radium Society, received the RSNA Gold Medal, and also numerous prestigious awards given to women in science. Edith Quimby was a Charter Member of AAPM. The AAPM Lifetime Achievement Award was renamed the Edith H. Quimby Lifetime Achievement Award in her honor in 2011. Marvin Martin Dixon Williams (1902–1981) Marvin Williams was born in Walla Walla, WA in 1902, and attended the same college as Edith Quimby, graduating from Whitman College in 1926. He was greatly influenced to go into medical physics by her accomplishments. During his early career, Williams worked with James Weatherwax in Philadelphia while he was working toward an M.S. from the University of Pennsylvania. In 1931 Williams was awarded a Ph.D. in Biophysics from the University of Minnesota, with the work actually performed at the Mayo Clinic Graduate School of the University. While completing his Ph.D. studies, Marvin met Dr. Paul Hodges who had returned from the Peiping Union Medical College in Peiping (now Beijing), China. Hodges suggested that a physicist be sent to Peiping to install x-ray therapy equipment and a radon plant. Williams accepted the position and, in 1931, he and his wife Orpha left for China. Before going to China, Williams had spent time with the physics group at Memorial Hospital to learn about the operation of a radon plant. In China, he constructed the radon plant, employing 0.25 g of radium, and also installed the x-ray therapy unit. Williams and his wife returned to the US in 1935, and he accepted a research position at the Mayo Clinic. In 1950, he became Professor of Biophysics at Mayo, where he taught physics and biophysics until his retirement in 1967. Williams was also very active in the American Board of Radiology where, from 1944 through 1977, he examined over 3000 radiologists and 250 physicists. Marvin Williams was a Charter member of AAPM, served as the fourth President of AAPM in 1963, and was the fourth recipient the AAPM Coolidge Award in 1975. The Marvin Williams Award was originally established as the highest award of the American College of Medical Physics. When various functions of the ACMP were absorbed into the AAPM in 2012, the Marvin M D Williams Professional Achievement Award became one of the AAPM’s highest honors. Learning Objectives: Become familiar with the persons in whose honor the three major AAPM Award are named Learn about the achievements and activities which influenced the AAPM to name these awards in their honor.« less

10 CFR 35.630 - Dosimetry equipment.

Code of Federal Regulations, 2010 CFR

2010-01-01

... system or source traceable to the National Institute of Standards and Technology (NIST) and published... American Association of Physicists in Medicine (AAPM). The calibration must have been performed within the...

10 CFR 35.630 - Dosimetry equipment.

Code of Federal Regulations, 2011 CFR

2011-01-01

... system or source traceable to the National Institute of Standards and Technology (NIST) and published... American Association of Physicists in Medicine (AAPM). The calibration must have been performed within the...

10 CFR 35.630 - Dosimetry equipment.

Code of Federal Regulations, 2013 CFR

2013-01-01

... system or source traceable to the National Institute of Standards and Technology (NIST) and published... American Association of Physicists in Medicine (AAPM). The calibration must have been performed within the...

10 CFR 35.630 - Dosimetry equipment.

Code of Federal Regulations, 2012 CFR

2012-01-01

... system or source traceable to the National Institute of Standards and Technology (NIST) and published... American Association of Physicists in Medicine (AAPM). The calibration must have been performed within the...

10 CFR 35.630 - Dosimetry equipment.

Code of Federal Regulations, 2014 CFR

2014-01-01

... system or source traceable to the National Institute of Standards and Technology (NIST) and published... American Association of Physicists in Medicine (AAPM). The calibration must have been performed within the...

Dose verification of eye plaque brachytherapy using spectroscopic dosimetry.

PubMed

Jarema, T; Cutajar, D; Weaver, M; Petasecca, M; Lerch, M; Kejda, A; Rosenfeld, A

2016-09-01

Eye plaque brachytherapy has been developed and refined for the last 80 years, demonstrating effective results in the treatment of ocular malignancies. Current dosimetry techniques for eye plaque brachytherapy (such as TLD- and film-based techniques) are time consuming and cannot be used prior to treatment in a sterile environment. The measurement of the expected dose distribution within the eye, prior to insertion within the clinical setting, would be advantageous, as any errors in source loading will lead to an erroneous dose distribution and inferior treatment outcomes. This study investigated the use of spectroscopic dosimetry techniques for real-time quality assurance of I-125 based eye plaques, immediately prior to insertion. A silicon detector based probe, operating in spectroscopy mode was constructed, containing a small (1 mm(3)) silicon detector, mounted within a ceramic holder, all encapsulated within a rubber sheath to prevent water infiltration of the electronics. Preliminary tests of the prototype demonstrated that the depth dose distribution through the central axis of an I-125 based eye plaque may be determined from AAPM Task Group 43 recommendations to a deviation of 6 % at 3 mm depth, 7 % at 5 mm depth, 1 % at 10 mm depth and 13 % at 20 mm depth, with the deviations attributed to the construction of the probe. A new probe design aims to reduce these discrepancies, however the concept of spectroscopic dosimetry shows great promise for use in eye plaque quality assurance in the clinical setting.

An exposure indicator for digital radiography: AAPM Task Group 116 (executive summary).

PubMed

Shepard, S Jeff; Wang, Jihong; Flynn, Michael; Gingold, Eric; Goldman, Lee; Krugh, Kerry; Leong, David L; Mah, Eugene; Ogden, Kent; Peck, Donald; Samei, Ehsan; Wang, Jihong; Willis, Charles E

2009-07-01

Digital radiographic imaging systems, such as those using photostimulable storage phosphor, amorphous selenium, amorphous silicon, CCD, and MOSFET technology, can produce adequate image quality over a much broader range of exposure levels than that of screen/film imaging systems. In screen/film imaging, the final image brightness and contrast are indicative of over- and underexposure. In digital imaging, brightness and contrast are often determined entirely by digital postprocessing of the acquired image data. Overexposure and underexposures are not readily recognizable. As a result, patient dose has a tendency to gradually increase over time after a department converts from screen/film-based imaging to digital radiographic imaging. The purpose of this report is to recommend a standard indicator which reflects the radiation exposure that is incident on a detector after every exposure event and that reflects the noise levels present in the image data. The intent is to facilitate the production of consistent, high quality digital radiographic images at acceptable patient doses. This should be based not on image optical density or brightness but on feedback regarding the detector exposure provided and actively monitored by the imaging system. A standard beam calibration condition is recommended that is based on RQA5 but uses filtration materials that are commonly available and simple to use. Recommendations on clinical implementation of the indices to control image quality and patient dose are derived from historical tolerance limits and presented as guidelines.

An exposure indicator for digital radiography: AAPM Task Group 116 (Executive Summary)

PubMed Central

Shepard, S. Jeff; Wang, Jihong; Flynn, Michael; Gingold, Eric; Goldman, Lee; Krugh, Kerry; Leong, David L.; Mah, Eugene; Ogden, Kent; Peck, Donald; Samei, Ehsan; Wang, Jihong; Willis, Charles E.

2009-01-01

Digital radiographic imaging systems, such as those using photostimulable storage phosphor, amorphous selenium, amorphous silicon, CCD, and MOSFET technology, can produce adequate image quality over a much broader range of exposure levels than that of screen/film imaging systems. In screen/film imaging, the final image brightness and contrast are indicative of over- and underexposure. In digital imaging, brightness and contrast are often determined entirely by digital postprocessing of the acquired image data. Overexposure and underexposures are not readily recognizable. As a result, patient dose has a tendency to gradually increase over time after a department converts from screen/film-based imaging to digital radiographic imaging. The purpose of this report is to recommend a standard indicator which reflects the radiation exposure that is incident on a detector after every exposure event and that reflects the noise levels present in the image data. The intent is to facilitate the production of consistent, high quality digital radiographic images at acceptable patient doses. This should be based not on image optical density or brightness but on feedback regarding the detector exposure provided and actively monitored by the imaging system. A standard beam calibration condition is recommended that is based on RQA5 but uses filtration materials that are commonly available and simple to use. Recommendations on clinical implementation of the indices to control image quality and patient dose are derived from historical tolerance limits and presented as guidelines. PMID:19673189

Radiological Society of North America

MedlinePlus

... Courses Electronic Education Exhibits RSNA Journals RSNA/AAPM Physics Modules RadioGraphics ABR Diagnostic Radiology Core Exam Study ... Brain Tumor Classification System In 2016, the World Health Organization (WHO) released an update to its brain ...

WE-AB-213-02: Status of Medical Physics Collaborations, and Projects in Latin America

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guzman, S.

AAPM projects and collaborations in Africa Adam Shulman (AA-SC Chair) The African Affairs Subcommittee (AA-SC) of the AAPM will present a multi-institutional approach to medical physics support in Africa. Current work to increase the quality of care and level of safety for the medical physics practice in Senegal, Ghana, and Zimbabwe will be presented, along with preliminary projects in Nigeria and Botswana. Because the task of addressing the needs of medical physics in countries across Africa is larger than one entity can accomplish on its own, the AA-SC has taken the approach of joining forces with multiple organizations such asmore » Radiating Hope and TreatSafely (NGO’s), the IAEA, companies like BrainLab, Varian and Elekta, medical volunteers and academic institutions such as NYU and Washington University. Elements of current projects include: 1) Distance training and evaluation of the quality of contouring and treatment planning, teaching treatment planning and other subjects, and troubleshooting using modern telecommunications technology in Senegal, Ghana, and Zimbabwe; 2) Assistance in the transition from 2D to 3D in Senegal and Zimbabwe; 3) Assistance in the transition from 3D to IMRT using in-house compensators in Senegal; 4) Modernizing the cancer center in Senegal and increasing safety and; 5) Training on on 3D techniques in Ghana; 6) Assisting a teaching and training radiation oncology center to be built in Zimbabwe; 7) Working with the ISEP Program in Sub-Saharan Africa; 8) Creating instructional videos on linac commissioning; 9) Working on a possible collaboration to train physicists in Nigeria. Building on past achievements, the subcommittee seeks to make a larger impact on the continent, as the number and size of projects increases and more human resources become available. The State of Medical Physics Collaborations and Projects in Latin America Sandra Guzman (Peru) The lack of Medical Physicists (MP) in many Latin American (LA) countries leads to recruitment of professionals with incomplete education. In most LA countries only one MP responsible for each Center is currently mandated. Currently there is a large disparity among MP training programs and there is significant debate about the standards of MP graduate education in many LA countries. There are no commonly recognized academic programs, not enough clinical training sites and clinical training is not typically considered as part of the MP work. Economic pressures and high workloads also impede the creation of more training centers. The increasing need of qualified MPs require establishing a coordinated system of national Education & Training Centers (ETC), to meet the international standards of education and training in Medical Physics. This shortfall calls for support of organizations such as the IOMP, AAPM, ALFIM, IAEA, etc. Examples from various LA countries, as well as some proposed solutions, will be presented. In particular, we will discuss the resources that the AAPM and its members can offer to support regional programs. The ‘Medical Imaging’ physicist in the emerging world: Challenges and opportunities - Caridad Borrás (WGNIMP Chair) While the role of radiation therapy physicists in the emerging world is reasonably well established, the role of medical imaging physicists is not. The only perceived needs in radiology departments are equipment quality control and radiation protection, tasks that can be done by a technologist or a service engineer. To change the situation, the International Basic Safety Standard, which is adopted/adapted world-wide as national radiation protection regulations, states: “For diagnostic radiological procedures and image guided interventional procedures, the requirements of these Standards for medical imaging, calibration, dosimetry and quality assurance, including the acceptance and commissioning of medical radiological equipment, are fulfilled by or under the oversight of, or with the documented advice of a medical physicist, whose degree of involvement is determined by the complexity of the radiological procedures and the associated radiation risks”. Details on how these requirements can be carried out in resource-limited settings will be described. IAEA support to medical physics in Africa and Latin America: achievements and challenges Ahmed Meghzifene (IAEA) Shortage of clinically qualified medical physicists in radiotherapy and imaging, insufficient and inadequate education and training programs, as well as a lack of professional recognition were identified as the main issues to be addressed by the IAEA. The IAEA developed a series of integrated projects aiming specifically at promoting the essential role of medical physicists in health care, developing harmonized guidelines on dosimetry and quality assurance, and supporting education and clinical training programs. The unique feature of the IAEA approach is support it provides for implementation of guidelines and education programs in Member States through its technical cooperation project. The presentation will summarize IAEA support to Latin America and Africa in the field of medical physics and will highlight how the new International Basic Safety Standards are expected to impact the medical physics practice in low and middle income countries. Learning Objectives: Learn about the shortage of qualified Medical Physicists in Africa and Latin America. Understand the reasons of this shortage. Learn about the ways to improve the situation and AAPM role in this process.« less

WE-AB-213-04: IAEA Support to Medical Physics in Africa and Latin America: Achievements and Challenges

DOE Office of Scientific and Technical Information (OSTI.GOV)

Meghzifene, A.

AAPM projects and collaborations in Africa Adam Shulman (AA-SC Chair) The African Affairs Subcommittee (AA-SC) of the AAPM will present a multi-institutional approach to medical physics support in Africa. Current work to increase the quality of care and level of safety for the medical physics practice in Senegal, Ghana, and Zimbabwe will be presented, along with preliminary projects in Nigeria and Botswana. Because the task of addressing the needs of medical physics in countries across Africa is larger than one entity can accomplish on its own, the AA-SC has taken the approach of joining forces with multiple organizations such asmore » Radiating Hope and TreatSafely (NGO’s), the IAEA, companies like BrainLab, Varian and Elekta, medical volunteers and academic institutions such as NYU and Washington University. Elements of current projects include: 1) Distance training and evaluation of the quality of contouring and treatment planning, teaching treatment planning and other subjects, and troubleshooting using modern telecommunications technology in Senegal, Ghana, and Zimbabwe; 2) Assistance in the transition from 2D to 3D in Senegal and Zimbabwe; 3) Assistance in the transition from 3D to IMRT using in-house compensators in Senegal; 4) Modernizing the cancer center in Senegal and increasing safety and; 5) Training on on 3D techniques in Ghana; 6) Assisting a teaching and training radiation oncology center to be built in Zimbabwe; 7) Working with the ISEP Program in Sub-Saharan Africa; 8) Creating instructional videos on linac commissioning; 9) Working on a possible collaboration to train physicists in Nigeria. Building on past achievements, the subcommittee seeks to make a larger impact on the continent, as the number and size of projects increases and more human resources become available. The State of Medical Physics Collaborations and Projects in Latin America Sandra Guzman (Peru) The lack of Medical Physicists (MP) in many Latin American (LA) countries leads to recruitment of professionals with incomplete education. In most LA countries only one MP responsible for each Center is currently mandated. Currently there is a large disparity among MP training programs and there is significant debate about the standards of MP graduate education in many LA countries. There are no commonly recognized academic programs, not enough clinical training sites and clinical training is not typically considered as part of the MP work. Economic pressures and high workloads also impede the creation of more training centers. The increasing need of qualified MPs require establishing a coordinated system of national Education & Training Centers (ETC), to meet the international standards of education and training in Medical Physics. This shortfall calls for support of organizations such as the IOMP, AAPM, ALFIM, IAEA, etc. Examples from various LA countries, as well as some proposed solutions, will be presented. In particular, we will discuss the resources that the AAPM and its members can offer to support regional programs. The ‘Medical Imaging’ physicist in the emerging world: Challenges and opportunities - Caridad Borrás (WGNIMP Chair) While the role of radiation therapy physicists in the emerging world is reasonably well established, the role of medical imaging physicists is not. The only perceived needs in radiology departments are equipment quality control and radiation protection, tasks that can be done by a technologist or a service engineer. To change the situation, the International Basic Safety Standard, which is adopted/adapted world-wide as national radiation protection regulations, states: “For diagnostic radiological procedures and image guided interventional procedures, the requirements of these Standards for medical imaging, calibration, dosimetry and quality assurance, including the acceptance and commissioning of medical radiological equipment, are fulfilled by or under the oversight of, or with the documented advice of a medical physicist, whose degree of involvement is determined by the complexity of the radiological procedures and the associated radiation risks”. Details on how these requirements can be carried out in resource-limited settings will be described. IAEA support to medical physics in Africa and Latin America: achievements and challenges Ahmed Meghzifene (IAEA) Shortage of clinically qualified medical physicists in radiotherapy and imaging, insufficient and inadequate education and training programs, as well as a lack of professional recognition were identified as the main issues to be addressed by the IAEA. The IAEA developed a series of integrated projects aiming specifically at promoting the essential role of medical physicists in health care, developing harmonized guidelines on dosimetry and quality assurance, and supporting education and clinical training programs. The unique feature of the IAEA approach is support it provides for implementation of guidelines and education programs in Member States through its technical cooperation project. The presentation will summarize IAEA support to Latin America and Africa in the field of medical physics and will highlight how the new International Basic Safety Standards are expected to impact the medical physics practice in low and middle income countries. Learning Objectives: Learn about the shortage of qualified Medical Physicists in Africa and Latin America. Understand the reasons of this shortage. Learn about the ways to improve the situation and AAPM role in this process.« less

WE-H-204-02: Part 1: History and Archives Resources at AIP for AAPM and Its Members

DOE Office of Scientific and Technical Information (OSTI.GOV)

Good, G.

“William D. Coolidge, Inventor of the Modern X-ray Tube” David J. Allard, M.S., CHP - Director, PA DEP Bureau of Radiation Protection William David Coolidge 1873–1975 was a research scientist and inventor of the modern X-ray tube. Besides Roentgen, with his 1895 discovery and subsequent studies of X-rays, perhaps no other individual contributed more to the advancement of X-ray technology than did Coolidge. He was born in Hudson, MA and received his Bachelor of Science degree from MIT in 1896. That same year he went to Europe to study under renowned physicists of the time. Coolidge received his Ph.D. summamore » cum laude from the University of Leipzig in 1899 and soon after joined the staff of MIT. While studying at Leipzig, he met Roentgen. In 1905 he was asked to join the newly established General Electric Research Laboratory in Schenectady, NY. He promptly began fundamental work on the production of ductile tungsten filaments as a replacement for fragile carbon filaments used in incandescent light bulbs. This improved light bulb was brought to market by GE in 1911. It was subsequent application of his tungsten work that led Coolidge to his studies in X ray production. Circa 1910, the state-of-the-art X-ray tube was a “gas tube” or “cold cathode” type tube. These crude X-ray tubes relied on residual gas molecules as a source of electrons for bombardment of low to medium atomic number metal targets. In 1912 Coolidge described the use of tungsten as an improved anode target material for X-ray tubes. Shortly after in 1913 he published a paper in Physical Review describing “A Powerful Roentgen Ray Tube With a Pure Electron Discharge.” This tube used a tungsten filament as a thermionic source of electrons under high vacuum to bombard a tungsten anode target. Great improvements in X-ray tube stability, output and performance were obtained with the “hot cathode” or “Coolidge tube.” With some variation in filament and target geometry, this 100 year old invention is the same basic X-ray tube used today in medicine, research and industry. In 1932 Coolidge became Director of the GE Laboratory, then in 1940 Vice-President and Director of Research. In 1941 he was a member of a small committee, appointed by President Franklin D. Roosevelt, to evaluate the military importance of research on uranium. This committee’s report led to the establishment of the Manhattan Engineering District for nuclear weapons development during WWII. Coolidge lived to be over 100 years old, he had 83 patents to his credit, numerous awards and honorary degrees, and in 1975 was elected to the National Inventor’s Hall of Fame. At the time he was the only inventor to receive this honor in his lifetime. Dr. Coolidge was also the first recipient of the AAPM’s highest science award - named in his honor. From notes of a day-long interview with Coolidge’s son Lawrence in the mid-1990s, previous biographies, publications, books, GE literature, historic photographs, e.g., a wonderful 1874 photo stereoview card with 1 year old baby “Willie Coolidge”, and other artifacts in the author’s collection, this presentation will review Dr. Coolidge’s amazing life, work, accomplishments and awards. “History and Archives Resources at AIP for AAPM and its Members” Gregory A. Good, Ph.D. - Director, AIP Center for History of Physics Melanie J. Mueller, MLIS - Acting Director, AIP Niels Bohr Library & Archives The American Institute of Physics established the Center for History of Physics and the Niels Bohr Library & Archives in the 1960s. Our shared mission is: To preserve and make known the history of the physical sciences. This talk will explore the many ways that AIP’s two history programs support the historical and archival activities of AAPM. Topics will include our ongoing oral history program, web outreach through exhibits and teaching guides, and archiving for AAPM and other Member Societies. We will focus in particular on materials in our collections related to the history of medical physics and to the history of AAPM. We will unveil and demonstrate a new “Archives Portal” that we are designing specifically to be useful to AAPM and its members. Learning Objectives: Study the background of the medical physicist - William David Coolidge Examine the time-line for his success Review the publications conceptualizing his works and progressions Realize what he invented Evaluate the importance of the invention Relate the success to national prominence Uncover how he influenced medical physicists today Find out how he was celebrated by the AAPM View the AIP established Center for History of Physics Consider the significant efforts and vision to preserve the history of medical physics Learn about the Niels Bohr Library & Archives Look back in time at medical physics in the 1960s Unveil and demonstrate a new “Archives Portal” that will be useful to AAPM.« less

WE-H-204-03: Part 2: History and Archives Resources at AIP for AAPM and Its Members

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mueller, M.

“William D. Coolidge, Inventor of the Modern X-ray Tube” David J. Allard, M.S., CHP - Director, PA DEP Bureau of Radiation Protection William David Coolidge 1873–1975 was a research scientist and inventor of the modern X-ray tube. Besides Roentgen, with his 1895 discovery and subsequent studies of X-rays, perhaps no other individual contributed more to the advancement of X-ray technology than did Coolidge. He was born in Hudson, MA and received his Bachelor of Science degree from MIT in 1896. That same year he went to Europe to study under renowned physicists of the time. Coolidge received his Ph.D. summamore » cum laude from the University of Leipzig in 1899 and soon after joined the staff of MIT. While studying at Leipzig, he met Roentgen. In 1905 he was asked to join the newly established General Electric Research Laboratory in Schenectady, NY. He promptly began fundamental work on the production of ductile tungsten filaments as a replacement for fragile carbon filaments used in incandescent light bulbs. This improved light bulb was brought to market by GE in 1911. It was subsequent application of his tungsten work that led Coolidge to his studies in X ray production. Circa 1910, the state-of-the-art X-ray tube was a “gas tube” or “cold cathode” type tube. These crude X-ray tubes relied on residual gas molecules as a source of electrons for bombardment of low to medium atomic number metal targets. In 1912 Coolidge described the use of tungsten as an improved anode target material for X-ray tubes. Shortly after in 1913 he published a paper in Physical Review describing “A Powerful Roentgen Ray Tube With a Pure Electron Discharge.” This tube used a tungsten filament as a thermionic source of electrons under high vacuum to bombard a tungsten anode target. Great improvements in X-ray tube stability, output and performance were obtained with the “hot cathode” or “Coolidge tube.” With some variation in filament and target geometry, this 100 year old invention is the same basic X-ray tube used today in medicine, research and industry. In 1932 Coolidge became Director of the GE Laboratory, then in 1940 Vice-President and Director of Research. In 1941 he was a member of a small committee, appointed by President Franklin D. Roosevelt, to evaluate the military importance of research on uranium. This committee’s report led to the establishment of the Manhattan Engineering District for nuclear weapons development during WWII. Coolidge lived to be over 100 years old, he had 83 patents to his credit, numerous awards and honorary degrees, and in 1975 was elected to the National Inventor’s Hall of Fame. At the time he was the only inventor to receive this honor in his lifetime. Dr. Coolidge was also the first recipient of the AAPM’s highest science award - named in his honor. From notes of a day-long interview with Coolidge’s son Lawrence in the mid-1990s, previous biographies, publications, books, GE literature, historic photographs, e.g., a wonderful 1874 photo stereoview card with 1 year old baby “Willie Coolidge”, and other artifacts in the author’s collection, this presentation will review Dr. Coolidge’s amazing life, work, accomplishments and awards. “History and Archives Resources at AIP for AAPM and its Members” Gregory A. Good, Ph.D. - Director, AIP Center for History of Physics Melanie J. Mueller, MLIS - Acting Director, AIP Niels Bohr Library & Archives The American Institute of Physics established the Center for History of Physics and the Niels Bohr Library & Archives in the 1960s. Our shared mission is: To preserve and make known the history of the physical sciences. This talk will explore the many ways that AIP’s two history programs support the historical and archival activities of AAPM. Topics will include our ongoing oral history program, web outreach through exhibits and teaching guides, and archiving for AAPM and other Member Societies. We will focus in particular on materials in our collections related to the history of medical physics and to the history of AAPM. We will unveil and demonstrate a new “Archives Portal” that we are designing specifically to be useful to AAPM and its members. Learning Objectives: Study the background of the medical physicist - William David Coolidge Examine the time-line for his success Review the publications conceptualizing his works and progressions Realize what he invented Evaluate the importance of the invention Relate the success to national prominence Uncover how he influenced medical physicists today Find out how he was celebrated by the AAPM View the AIP established Center for History of Physics Consider the significant efforts and vision to preserve the history of medical physics Learn about the Niels Bohr Library & Archives Look back in time at medical physics in the 1960s Unveil and demonstrate a new “Archives Portal” that will be useful to AAPM.« less

TU-A-BRD-01: Outcomes of Hypofractionated Treatments - Initial Results of the WGSBRT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, X; Lee, P; Ohri, N

2014-06-15

Stereotactic Body Radiation Therapy (SBRT) has emerged in recent decades as a treatment paradigm that is becoming increasingly important in clinical practice. Clinical outcomes data are rapidly accumulating. Although published relations between outcomes and dose distributions are still sparse, the field has progressed to the point where evidence-based normal tissue dose-volume constraints, prescription strategies, and Tumor Control Probability (TCP) and Normal Tissue Complication Probability (NTCP) models can be developed. The Working Group on SBRT (WGSBRT), under the Biological Effects Subcommittee of AAPM, is a group of physicists and physicians working in the area of SBRT. It is currently performing criticalmore » literature reviews to extract and synthesize usable data and to develop guidelines and models to aid with safe and effective treatment. The group is investigating clinically relevant findings from SBRT in six anatomical regions: Cranial, Head and Neck, Thoracic, Abdominal, Pelvic, and Spinal. In this session of AAPM 2014, interim results are presented on TCP for lung and liver, NTCP for thoracic organs, and radiobiological foundations:• Lung TCP: Detailed modeling of TCP data from 118 published studies on early stage lung SBRT investigates dose response and hypothesized mechanisms to explain the improved outcomes of SBRT. This is presented from the perspective of a physicist, a physician, and a radiobiologist.• Liver TCP: For primary and metastatic liver tumors, individual patient data were extracted from published reports to examine the effects of biologically effective dose on local control.• Thoracic NTCP: Clinically significant SBRT toxicity of lung, rib / chest wall and other structures are evaluated and compared among published clinical data, in terms of risk, risk factors, and safe practice.• Improving the clinical utility of published toxicity reports from SBRT and Hypofractionated treatments. What do we want, and how do we get it? Methods and problems of synthesizing data from published reports. Learning Objectives: Common SBRT fractionation schemes and current evidence for efficacy. Evidence for normal tissue tolerances in hypofractionated treatments. Clinically relevant radiobiological effects at large fraction sizes.« less

A personal rapid transit/airport automated people mover comparison.

DOT National Transportation Integrated Search

2008-01-01

Airport automated people movers (AAPM) typically consist of driverless trains with : up to about four cars each capable of carrying 20 to 100 passengers who are mostly : standing. They have been successfully used for surface transportation in airport...

The relationship between organ dose and patient size in tube current modulated adult thoracic CT scans

NASA Astrophysics Data System (ADS)

Khatonabadi, Maryam; Zhang, Di; Yang, Jeffrey; DeMarco, John J.; Cagnon, Chris C.; McNitt-Gray, Michael F.

2012-03-01

Recently published AAPM Task Group 204 developed conversion coefficients that use scanner reported CTDIvol to estimate dose to the center of patient undergoing fixed tube current body exam. However, most performed CT exams use TCM to reduce dose to patients. Therefore, the purpose of this study was to investigate the correlation between organ dose and a variety of patient size metrics in adult chest CT scans that use tube current modulation (TCM). Monte Carlo simulations were performed for 32 voxelized models with contoured lungs and glandular breasts tissue, consisting of females and males. These simulations made use of patient's actual TCM data to estimate organ dose. Using image data, different size metrics were calculated, these measurements were all performed on one slice, at the level of patient's nipple. Estimated doses were normalized by scanner-reported CTDIvol and plotted versus different metrics. CTDIvol values were plotted versus different metrics to look at scanner's output versus size. The metrics performed similarly in terms of correlating with organ dose. Looking at each gender separately, for male models normalized lung dose showed a better linear correlation (r2=0.91) with effective diameter, while female models showed higher correlation (r2=0.59) with the anterior-posterior measurement. There was essentially no correlation observed between size and CTDIvol-normalized breast dose. However, a linear relationship was observed between absolute breast dose and size. Dose to lungs and breasts were consistently higher in females with similar size as males which could be due to shape and composition differences between genders in the thoracic region.

TU-F-201-00: Radiochromic Film Dosimetry Update

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

Since the introduction of radiochromic films (RCF) for radiation dosimetry, the scope of RCF dosimetry has expanded steadily to include many medical applications, such as radiation therapy and diagnostic radiology. The AAPM Task Group (TG) 55 published a report on the recommendations for RCF dosimetry in 1998. As the technology is advancing rapidly, and its routine clinical use is expanding, TG 235 has been formed to provide an update to TG-55 on radiochromic film dosimetry. RCF dosimetry applications in clinical radiotherapy have become even more widespread, expanding from primarily brachytherapy and radiosurgery applications, and gravitating towards (but not limited to)more » external beam therapy (photon, electron and protons), such as quality assurance for IMRT, VMAT, Tomotherapy, SRS/SRT, and SBRT. In addition, RCF applications now extend to measurements of radiation dose in particle beams and patients undergoing medical exams, especially fluoroscopically guided interventional procedures and CT. The densitometers/scanners used for RCF dosimetry have also evolved from the He-Ne laser scanner to CCD-based scanners, including roller-based scanner, light box-based digital camera, and flatbed color scanner. More recently, multichannel RCF dosimetry introduced a new paradigm for external beam dose QA for its high accuracy and efficiency. This course covers in detail the recent advancements in RCF dosimetry. Learning Objectives: Introduce the paradigm shift on multichannel film dosimetry Outline the procedures to achieve accurate dosimetry with a RCF dosimetry system Provide comprehensive guidelines on RCF dosimetry for various clinical applications One of the speakers has a research agreement from Ashland Inc., the manufacturer of Gafchromic film.« less

TU-F-201-01: General Aspects of Radiochromic Film Dosimetry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Niroomand-Rad, A.

Since the introduction of radiochromic films (RCF) for radiation dosimetry, the scope of RCF dosimetry has expanded steadily to include many medical applications, such as radiation therapy and diagnostic radiology. The AAPM Task Group (TG) 55 published a report on the recommendations for RCF dosimetry in 1998. As the technology is advancing rapidly, and its routine clinical use is expanding, TG 235 has been formed to provide an update to TG-55 on radiochromic film dosimetry. RCF dosimetry applications in clinical radiotherapy have become even more widespread, expanding from primarily brachytherapy and radiosurgery applications, and gravitating towards (but not limited to)more » external beam therapy (photon, electron and protons), such as quality assurance for IMRT, VMAT, Tomotherapy, SRS/SRT, and SBRT. In addition, RCF applications now extend to measurements of radiation dose in particle beams and patients undergoing medical exams, especially fluoroscopically guided interventional procedures and CT. The densitometers/scanners used for RCF dosimetry have also evolved from the He-Ne laser scanner to CCD-based scanners, including roller-based scanner, light box-based digital camera, and flatbed color scanner. More recently, multichannel RCF dosimetry introduced a new paradigm for external beam dose QA for its high accuracy and efficiency. This course covers in detail the recent advancements in RCF dosimetry. Learning Objectives: Introduce the paradigm shift on multichannel film dosimetry Outline the procedures to achieve accurate dosimetry with a RCF dosimetry system Provide comprehensive guidelines on RCF dosimetry for various clinical applications One of the speakers has a research agreement from Ashland Inc., the manufacturer of Gafchromic film.« less

Performance assessment of a programmable five degrees-of-freedom motion platform for quality assurance of motion management techniques in radiotherapy.

PubMed

Huang, Chen-Yu; Keall, Paul; Rice, Adam; Colvill, Emma; Ng, Jin Aun; Booth, Jeremy T

2017-09-01

Inter-fraction and intra-fraction motion management methods are increasingly applied clinically and require the development of advanced motion platforms to facilitate testing and quality assurance program development. The aim of this study was to assess the performance of a 5 degrees-of-freedom (DoF) programmable motion platform HexaMotion (ScandiDos, Uppsala, Sweden) towards clinically observed tumor motion range, velocity, acceleration and the accuracy requirements of SABR prescribed in AAPM Task Group 142. Performance specifications for the motion platform were derived from literature regarding the motion characteristics of prostate and lung tumor targets required for real time motion management. The performance of the programmable motion platform was evaluated against (1) maximum range, velocity and acceleration (5 DoF), (2) static position accuracy (5 DoF) and (3) dynamic position accuracy using patient-derived prostate and lung tumor motion traces (3 DoF). Translational motion accuracy was compared against electromagnetic transponder measurements. Rotation was benchmarked with a digital inclinometer. The static accuracy and reproducibility for translation and rotation was <0.1 mm or <0.1°, respectively. The accuracy of reproducing dynamic patient motion was <0.3 mm. The motion platform's range met the need to reproduce clinically relevant translation and rotation ranges and its accuracy met the TG 142 requirements for SABR. The range, velocity and acceleration of the motion platform are sufficient to reproduce lung and prostate tumor motion for motion management. Programmable motion platforms are valuable tools in the investigation, quality assurance and commissioning of motion management systems in radiation oncology.

Evaluation of a Proposed Biodegradable 188Re Source for Brachytherapy Application

PubMed Central

Khorshidi, Abdollah; Ahmadinejad, Marjan; Hamed Hosseini, S.

2015-01-01

Abstract This study aimed to evaluate dosimetric characteristics based on Monte Carlo (MC) simulations for a proposed beta emitter bioglass 188Re seed for internal radiotherapy applications. The bioactive glass seed has been developed using the sol-gel technique. The simulations were performed for the seed using MC radiation transport code to investigate the dosimetric factors recommended by the AAPM Task Group 60 (TG-60). Dose distributions due to the beta and photon radiation were predicted at different radial distances surrounding the source. The dose rate in water at the reference point was calculated to be 7.43 ± 0.5 cGy/h/μCi. The dosimetric factors consisting of the reference point dose rate, D(r0,θ0), the radial dose function, g(r), the 2-dimensional anisotropy function, F(r,θ), the 1-dimensional anisotropy function, φan(r), and the R90 quantity were estimated and compared with several available beta-emitting sources. The element 188Re incorporated in bioactive glasses produced by the sol-gel technique provides a suitable solution for producing new materials for seed implants applied to brachytherapy applications in prostate and liver cancers treatment. Dose distribution of 188Re seed was greater isotropic than other commercially attainable encapsulated seeds, since it has no end weld to attenuate radiation. The beta radiation-emitting 188Re source provides high doses of local radiation to the tumor tissue and the short range of the beta particles limit damage to the adjacent normal tissue. PMID:26181543

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chiu-Tsao, S.

Since the introduction of radiochromic films (RCF) for radiation dosimetry, the scope of RCF dosimetry has expanded steadily to include many medical applications, such as radiation therapy and diagnostic radiology. The AAPM Task Group (TG) 55 published a report on the recommendations for RCF dosimetry in 1998. As the technology is advancing rapidly, and its routine clinical use is expanding, TG 235 has been formed to provide an update to TG-55 on radiochromic film dosimetry. RCF dosimetry applications in clinical radiotherapy have become even more widespread, expanding from primarily brachytherapy and radiosurgery applications, and gravitating towards (but not limited to)more » external beam therapy (photon, electron and protons), such as quality assurance for IMRT, VMAT, Tomotherapy, SRS/SRT, and SBRT. In addition, RCF applications now extend to measurements of radiation dose in particle beams and patients undergoing medical exams, especially fluoroscopically guided interventional procedures and CT. The densitometers/scanners used for RCF dosimetry have also evolved from the He-Ne laser scanner to CCD-based scanners, including roller-based scanner, light box-based digital camera, and flatbed color scanner. More recently, multichannel RCF dosimetry introduced a new paradigm for external beam dose QA for its high accuracy and efficiency. This course covers in detail the recent advancements in RCF dosimetry. Learning Objectives: Introduce the paradigm shift on multichannel film dosimetry Outline the procedures to achieve accurate dosimetry with a RCF dosimetry system Provide comprehensive guidelines on RCF dosimetry for various clinical applications One of the speakers has a research agreement from Ashland Inc., the manufacturer of Gafchromic film.« less

TU-AB-BRD-03: Fault Tree Analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dunscombe, P.

2015-06-15

Current quality assurance and quality management guidelines provided by various professional organizations are prescriptive in nature, focusing principally on performance characteristics of planning and delivery devices. However, published analyses of events in radiation therapy show that most events are often caused by flaws in clinical processes rather than by device failures. This suggests the need for the development of a quality management program that is based on integrated approaches to process and equipment quality assurance. Industrial engineers have developed various risk assessment tools that are used to identify and eliminate potential failures from a system or a process before amore » failure impacts a customer. These tools include, but are not limited to, process mapping, failure modes and effects analysis, fault tree analysis. Task Group 100 of the American Association of Physicists in Medicine has developed these tools and used them to formulate an example risk-based quality management program for intensity-modulated radiotherapy. This is a prospective risk assessment approach that analyzes potential error pathways inherent in a clinical process and then ranks them according to relative risk, typically before implementation, followed by the design of a new process or modification of the existing process. Appropriate controls are then put in place to ensure that failures are less likely to occur and, if they do, they will more likely be detected before they propagate through the process, compromising treatment outcome and causing harm to the patient. Such a prospective approach forms the basis of the work of Task Group 100 that has recently been approved by the AAPM. This session will be devoted to a discussion of these tools and practical examples of how these tools can be used in a given radiotherapy clinic to develop a risk based quality management program. Learning Objectives: Learn how to design a process map for a radiotherapy process Learn how to perform failure modes and effects analysis analysis for a given process Learn what fault trees are all about Learn how to design a quality management program based upon the information obtained from process mapping, failure modes and effects analysis and fault tree analysis. Dunscombe: Director, TreatSafely, LLC and Center for the Assessment of Radiological Sciences; Consultant to IAEA and Varian Thomadsen: President, Center for the Assessment of Radiological Sciences Palta: Vice President of the Center for the Assessment of Radiological Sciences.« less

TU-AB-BRD-01: Process Mapping

DOE Office of Scientific and Technical Information (OSTI.GOV)

Palta, J.

2015-06-15

Current quality assurance and quality management guidelines provided by various professional organizations are prescriptive in nature, focusing principally on performance characteristics of planning and delivery devices. However, published analyses of events in radiation therapy show that most events are often caused by flaws in clinical processes rather than by device failures. This suggests the need for the development of a quality management program that is based on integrated approaches to process and equipment quality assurance. Industrial engineers have developed various risk assessment tools that are used to identify and eliminate potential failures from a system or a process before amore » failure impacts a customer. These tools include, but are not limited to, process mapping, failure modes and effects analysis, fault tree analysis. Task Group 100 of the American Association of Physicists in Medicine has developed these tools and used them to formulate an example risk-based quality management program for intensity-modulated radiotherapy. This is a prospective risk assessment approach that analyzes potential error pathways inherent in a clinical process and then ranks them according to relative risk, typically before implementation, followed by the design of a new process or modification of the existing process. Appropriate controls are then put in place to ensure that failures are less likely to occur and, if they do, they will more likely be detected before they propagate through the process, compromising treatment outcome and causing harm to the patient. Such a prospective approach forms the basis of the work of Task Group 100 that has recently been approved by the AAPM. This session will be devoted to a discussion of these tools and practical examples of how these tools can be used in a given radiotherapy clinic to develop a risk based quality management program. Learning Objectives: Learn how to design a process map for a radiotherapy process Learn how to perform failure modes and effects analysis analysis for a given process Learn what fault trees are all about Learn how to design a quality management program based upon the information obtained from process mapping, failure modes and effects analysis and fault tree analysis. Dunscombe: Director, TreatSafely, LLC and Center for the Assessment of Radiological Sciences; Consultant to IAEA and Varian Thomadsen: President, Center for the Assessment of Radiological Sciences Palta: Vice President of the Center for the Assessment of Radiological Sciences.« less

TU-AB-BRD-04: Development of Quality Management Program

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thomadsen, B.

2015-06-15

Current quality assurance and quality management guidelines provided by various professional organizations are prescriptive in nature, focusing principally on performance characteristics of planning and delivery devices. However, published analyses of events in radiation therapy show that most events are often caused by flaws in clinical processes rather than by device failures. This suggests the need for the development of a quality management program that is based on integrated approaches to process and equipment quality assurance. Industrial engineers have developed various risk assessment tools that are used to identify and eliminate potential failures from a system or a process before amore » failure impacts a customer. These tools include, but are not limited to, process mapping, failure modes and effects analysis, fault tree analysis. Task Group 100 of the American Association of Physicists in Medicine has developed these tools and used them to formulate an example risk-based quality management program for intensity-modulated radiotherapy. This is a prospective risk assessment approach that analyzes potential error pathways inherent in a clinical process and then ranks them according to relative risk, typically before implementation, followed by the design of a new process or modification of the existing process. Appropriate controls are then put in place to ensure that failures are less likely to occur and, if they do, they will more likely be detected before they propagate through the process, compromising treatment outcome and causing harm to the patient. Such a prospective approach forms the basis of the work of Task Group 100 that has recently been approved by the AAPM. This session will be devoted to a discussion of these tools and practical examples of how these tools can be used in a given radiotherapy clinic to develop a risk based quality management program. Learning Objectives: Learn how to design a process map for a radiotherapy process Learn how to perform failure modes and effects analysis analysis for a given process Learn what fault trees are all about Learn how to design a quality management program based upon the information obtained from process mapping, failure modes and effects analysis and fault tree analysis. Dunscombe: Director, TreatSafely, LLC and Center for the Assessment of Radiological Sciences; Consultant to IAEA and Varian Thomadsen: President, Center for the Assessment of Radiological Sciences Palta: Vice President of the Center for the Assessment of Radiological Sciences.« less

TU-AB-BRD-02: Failure Modes and Effects Analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huq, M.

2015-06-15

Current quality assurance and quality management guidelines provided by various professional organizations are prescriptive in nature, focusing principally on performance characteristics of planning and delivery devices. However, published analyses of events in radiation therapy show that most events are often caused by flaws in clinical processes rather than by device failures. This suggests the need for the development of a quality management program that is based on integrated approaches to process and equipment quality assurance. Industrial engineers have developed various risk assessment tools that are used to identify and eliminate potential failures from a system or a process before amore » failure impacts a customer. These tools include, but are not limited to, process mapping, failure modes and effects analysis, fault tree analysis. Task Group 100 of the American Association of Physicists in Medicine has developed these tools and used them to formulate an example risk-based quality management program for intensity-modulated radiotherapy. This is a prospective risk assessment approach that analyzes potential error pathways inherent in a clinical process and then ranks them according to relative risk, typically before implementation, followed by the design of a new process or modification of the existing process. Appropriate controls are then put in place to ensure that failures are less likely to occur and, if they do, they will more likely be detected before they propagate through the process, compromising treatment outcome and causing harm to the patient. Such a prospective approach forms the basis of the work of Task Group 100 that has recently been approved by the AAPM. This session will be devoted to a discussion of these tools and practical examples of how these tools can be used in a given radiotherapy clinic to develop a risk based quality management program. Learning Objectives: Learn how to design a process map for a radiotherapy process Learn how to perform failure modes and effects analysis analysis for a given process Learn what fault trees are all about Learn how to design a quality management program based upon the information obtained from process mapping, failure modes and effects analysis and fault tree analysis. Dunscombe: Director, TreatSafely, LLC and Center for the Assessment of Radiological Sciences; Consultant to IAEA and Varian Thomadsen: President, Center for the Assessment of Radiological Sciences Palta: Vice President of the Center for the Assessment of Radiological Sciences.« less

MO-DE-304-01: The Abt Study of Medical Physicist Work Values for Radiation Oncology Physics Services: Round IV

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mills, M.

The Abt study of medical physicist work values for radiation oncology physics services, Round IV is completed. It supersedes the Abt III study of 2008. The 2015 Abt study measured qualified medical physicist (QMP) work associated with routine radiation oncology procedures as well as some special procedures. As before, a work model was created to allow the medical physicist to defend QMP work based on both routine and special procedures service mix. The work model can be used to develop a cost justification report for setting charges for radiation oncology physics services. The Abt study Round IV was designed tomore » empower the medical physicist to negotiate a service or employment contract with providers based on measured national QMP workforce and staffing data. For a variety of reasons, the diagnostic imaging contingent of AAPM has had a more difficult time trying estimate workforce requirements than their therapy counterparts. Over the past several years, the Diagnostic Work and Workforce Study Subcommittee (DWWSS) has collected survey data from AAPM members, but the data have been very difficult to interpret. The DWWSS has reached out to include more AAPM volunteers to create a more full and accurate representation of actual clinical practice models on the subcommittee. Though much work remains, through hours of discussion and brainstorming, the DWWSS has somewhat of a clear path forward. This talk will provide attendees with an update on the efforts of the subcommittee. Learning Objectives: Understand the new information documented in the Abt studies. Understand how to use the Abt studies to justify medical physicist staffing. Learn relevant historical information on imaging physicist workforce. Understand the process of the DWWSS in 2014. Understand the intended path forward for the DWWSS.« less

MO-DE-304-02: Diagnostic Workforce Subcommittee Status and Direction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gress, D.

2015-06-15

The Abt study of medical physicist work values for radiation oncology physics services, Round IV is completed. It supersedes the Abt III study of 2008. The 2015 Abt study measured qualified medical physicist (QMP) work associated with routine radiation oncology procedures as well as some special procedures. As before, a work model was created to allow the medical physicist to defend QMP work based on both routine and special procedures service mix. The work model can be used to develop a cost justification report for setting charges for radiation oncology physics services. The Abt study Round IV was designed tomore » empower the medical physicist to negotiate a service or employment contract with providers based on measured national QMP workforce and staffing data. For a variety of reasons, the diagnostic imaging contingent of AAPM has had a more difficult time trying estimate workforce requirements than their therapy counterparts. Over the past several years, the Diagnostic Work and Workforce Study Subcommittee (DWWSS) has collected survey data from AAPM members, but the data have been very difficult to interpret. The DWWSS has reached out to include more AAPM volunteers to create a more full and accurate representation of actual clinical practice models on the subcommittee. Though much work remains, through hours of discussion and brainstorming, the DWWSS has somewhat of a clear path forward. This talk will provide attendees with an update on the efforts of the subcommittee. Learning Objectives: Understand the new information documented in the Abt studies. Understand how to use the Abt studies to justify medical physicist staffing. Learn relevant historical information on imaging physicist workforce. Understand the process of the DWWSS in 2014. Understand the intended path forward for the DWWSS.« less

MO-DE-304-00: Workforce Assessment Committee Update

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

2015-06-15

The Abt study of medical physicist work values for radiation oncology physics services, Round IV is completed. It supersedes the Abt III study of 2008. The 2015 Abt study measured qualified medical physicist (QMP) work associated with routine radiation oncology procedures as well as some special procedures. As before, a work model was created to allow the medical physicist to defend QMP work based on both routine and special procedures service mix. The work model can be used to develop a cost justification report for setting charges for radiation oncology physics services. The Abt study Round IV was designed tomore » empower the medical physicist to negotiate a service or employment contract with providers based on measured national QMP workforce and staffing data. For a variety of reasons, the diagnostic imaging contingent of AAPM has had a more difficult time trying estimate workforce requirements than their therapy counterparts. Over the past several years, the Diagnostic Work and Workforce Study Subcommittee (DWWSS) has collected survey data from AAPM members, but the data have been very difficult to interpret. The DWWSS has reached out to include more AAPM volunteers to create a more full and accurate representation of actual clinical practice models on the subcommittee. Though much work remains, through hours of discussion and brainstorming, the DWWSS has somewhat of a clear path forward. This talk will provide attendees with an update on the efforts of the subcommittee. Learning Objectives: Understand the new information documented in the Abt studies. Understand how to use the Abt studies to justify medical physicist staffing. Learn relevant historical information on imaging physicist workforce. Understand the process of the DWWSS in 2014. Understand the intended path forward for the DWWSS.« less

MO-D-16A-01: International Day of Medical Physics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cheung, K; Damilakis, J

International Organization for Medical Physics (IOMP) which represents medical physicists in more than 80 countries decided to celebrate 7th November, birth date of the Polish and naturalized-French physicist Marie Sklodowska-Curie, as International Day of Medical Physics (IDMP). The main purpose of the initiative is to raise the visibility and awareness of medical physicist in the global community, to introduce ourselves to the general public, and bring a message to the community that a group of health professionals, the medical physicists are there to help the patients and other health professionals. First celebration was done in 2013 and now IDMP willmore » be celebrated every year. The theme of IDMP will be different each year. The theme for 2013 was ‘Radiation exposure from medical procedures, ask the Medical Physicist’. The inaugural event was celebrated in 23 countries and the amount of attention gained was remarkable. Main IDMP events were held in Poland, birthplace of Marie Curie, and France, workplace of Marie Curie. This year IOMP celebrates the 2nd IDMP and theme will be ‘Looking into the body-Advancement in Imaging through Medical Physics’ to draw attention to the profound contributions Medical Physics has made to the use of ionizing and non-ionizing radiation for the imaging of human body. A number of countries have informed about events that they are going to organize on IDMP. This gives wide attention to medical physics globally. AAPM is a major and important member of IOMP. It is hoped that AAPM will join in organizing activities. Learning Objectives: To learn about International Day of Medical Physics To become familiar with how first IDMP was celebrated in 2013 and learning achieved To understand on future plans for IDMPs.« less

Dosimetric characterization of the (60)Co BEBIG Co0.A86 high dose rate brachytherapy source using PENELOPE.

PubMed

Guerrero, Rafael; Almansa, Julio F; Torres, Javier; Lallena, Antonio M

2014-12-01

(60)Co sources are being used as an alternative to (192)Ir sources in high dose rate brachytherapy treatments. In a recent document from AAPM and ESTRO, a consensus dataset for the (60)Co BEBIG (model Co0.A86) high dose rate source was prepared by using results taken from different publications due to discrepancies observed among them. The aim of the present work is to provide a new calculation of the dosimetric characteristics of that (60)Co source according to the recommendations of the AAPM and ESTRO report. Radial dose function, anisotropy function, air-kerma strength, dose rate constant and absorbed dose rate in water have been calculated and compared to the results of previous works. Simulations using the two different geometries considered by other authors have been carried out and the effect of the cable density and length has been studied. Copyright © 2014 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

Procedures for establishing and maintaining consistent air-kerma strength standards for low-energy, photon-emitting brachytherapy sources: recommendations of the Calibration Laboratory Accreditation Subcommittee of the American Association of Physicists in Medicine.

PubMed

DeWerd, Larry A; Huq, M Saiful; Das, Indra J; Ibbott, Geoffrey S; Hanson, William F; Slowey, Thomas W; Williamson, Jeffrey F; Coursey, Bert M

2004-03-01

Low dose rate brachytherapy is being used extensively for the treatment of prostate cancer. As of September 2003, there are a total of thirteen 125I and seven 103Pd sources that have calibrations from the National Institute of Standards and Technology (NIST) and the Accredited Dosimetry Calibration Laboratories (ADCLs) of the American Association of Physicists in Medicine (AAPM). The dosimetry standards for these sources are traceable to the NIST wide-angle free-air chamber. Procedures have been developed by the AAPM Calibration Laboratory Accreditation Subcommittee to standardize quality assurance and calibration, and to maintain the dosimetric traceability of these sources to ensure accurate clinical dosimetry. A description of these procedures is provided to the clinical users for traceability purposes as well as to provide guidance to the manufacturers of brachytherapy sources and ADCLs with regard to these procedures.

Radiation Oncology Physics and Medical Physics Education

NASA Astrophysics Data System (ADS)

Bourland, Dan

2011-10-01

Medical physics, an applied field of physics, is the applications of physics in medicine. Medical physicists are essential professionals in contemporary healthcare, contributing primarily to the diagnosis and treatment of diseases through numerous inventions, advances, and improvements in medical imaging and cancer treatment. Clinical service, research, and teaching by medical physicists benefits thousands of patients and other individuals every day. This talk will cover three main topics. First, exciting current research and development areas in the medical physics sub-specialty of radiation oncology physics will be described, including advanced oncology imaging for treatment simulation, image-guided radiation therapy, and biologically-optimized radiation treatment. Challenges in patient safety in high-technology radiation treatments will be briefly reviewed. Second, the educational path to becoming a medical physicist will be reviewed, including undergraduate foundations, graduate training, residency, board certification, and career opportunities. Third, I will introduce the American Association of Physicists in Medicine (AAPM), which is the professional society that represents, advocates, and advances the field of medical physics (www.aapm.org).

Development of independent MU/treatment time verification algorithm for non-IMRT treatment planning: A clinical experience

NASA Astrophysics Data System (ADS)

Tatli, Hamza; Yucel, Derya; Yilmaz, Sercan; Fayda, Merdan

2018-02-01

The aim of this study is to develop an algorithm for independent MU/treatment time (TT) verification for non-IMRT treatment plans, as a part of QA program to ensure treatment delivery accuracy. Two radiotherapy delivery units and their treatment planning systems (TPS) were commissioned in Liv Hospital Radiation Medicine Center, Tbilisi, Georgia. Beam data were collected according to vendors' collection guidelines, and AAPM reports recommendations, and processed by Microsoft Excel during in-house algorithm development. The algorithm is designed and optimized for calculating SSD and SAD treatment plans, based on AAPM TG114 dose calculation recommendations, coded and embedded in MS Excel spreadsheet, as a preliminary verification algorithm (VA). Treatment verification plans were created by TPSs based on IAEA TRS 430 recommendations, also calculated by VA, and point measurements were collected by solid water phantom, and compared. Study showed that, in-house VA can be used for non-IMRT plans MU/TT verifications.

MO-FG-209-05: Towards a Feature-Based Anthropomorphic Model Observer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Avanaki, A.

2016-06-15

This symposium will review recent advances in the simulation methods for evaluation of novel breast imaging systems – the subject of AAPM Task Group TG234. Our focus will be on the various approaches to development and validation of software anthropomorphic phantoms and their use in the statistical assessment of novel imaging systems using such phantoms along with computational models for the x-ray image formation process. Due to the dynamic development and complex design of modern medical imaging systems, the simulation of anatomical structures, image acquisition modalities, and the image perception and analysis offers substantial benefits of reduced cost, duration, andmore » radiation exposure, as well as the known ground-truth and wide variability in simulated anatomies. For these reasons, Virtual Clinical Trials (VCTs) have been increasingly accepted as a viable tool for preclinical assessment of x-ray and other breast imaging methods. Activities of TG234 have encompassed the optimization of protocols for simulation studies, including phantom specifications, the simulated data representation, models of the imaging process, and statistical assessment of simulated images. The symposium will discuss the state-of-the-science of VCTs for novel breast imaging systems, emphasizing recent developments and future directions. Presentations will discuss virtual phantoms for intermodality breast imaging performance comparisons, extension of the breast anatomy simulation to the cellular level, optimized integration of the simulated imaging chain, and the novel directions in the observer models design. Learning Objectives: Review novel results in developing and applying virtual phantoms for inter-modality breast imaging performance comparisons; Discuss the efforts to extend the computer simulation of breast anatomy and pathology to the cellular level; Summarize the state of the science in optimized integration of modules in the simulated imaging chain; Compare novel directions in the design of observer models for task based validation of imaging systems. PB: Research funding support from the NIH, NSF, and Komen for the Cure; NIH funded collaboration with Barco, Inc. and Hologic, Inc.; Consultant to Delaware State Univ. and NCCPM, UK. AA: Employed at Barco Healthcare.; P. Bakic, NIH: (NIGMS P20 #GM103446, NCI R01 #CA154444); M. Das, NIH Research grants.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Graff, C.

This symposium will review recent advances in the simulation methods for evaluation of novel breast imaging systems – the subject of AAPM Task Group TG234. Our focus will be on the various approaches to development and validation of software anthropomorphic phantoms and their use in the statistical assessment of novel imaging systems using such phantoms along with computational models for the x-ray image formation process. Due to the dynamic development and complex design of modern medical imaging systems, the simulation of anatomical structures, image acquisition modalities, and the image perception and analysis offers substantial benefits of reduced cost, duration, andmore » radiation exposure, as well as the known ground-truth and wide variability in simulated anatomies. For these reasons, Virtual Clinical Trials (VCTs) have been increasingly accepted as a viable tool for preclinical assessment of x-ray and other breast imaging methods. Activities of TG234 have encompassed the optimization of protocols for simulation studies, including phantom specifications, the simulated data representation, models of the imaging process, and statistical assessment of simulated images. The symposium will discuss the state-of-the-science of VCTs for novel breast imaging systems, emphasizing recent developments and future directions. Presentations will discuss virtual phantoms for intermodality breast imaging performance comparisons, extension of the breast anatomy simulation to the cellular level, optimized integration of the simulated imaging chain, and the novel directions in the observer models design. Learning Objectives: Review novel results in developing and applying virtual phantoms for inter-modality breast imaging performance comparisons; Discuss the efforts to extend the computer simulation of breast anatomy and pathology to the cellular level; Summarize the state of the science in optimized integration of modules in the simulated imaging chain; Compare novel directions in the design of observer models for task based validation of imaging systems. PB: Research funding support from the NIH, NSF, and Komen for the Cure; NIH funded collaboration with Barco, Inc. and Hologic, Inc.; Consultant to Delaware State Univ. and NCCPM, UK. AA: Employed at Barco Healthcare.; P. Bakic, NIH: (NIGMS P20 #GM103446, NCI R01 #CA154444); M. Das, NIH Research grants.« less

76 FR 32409 - Medicare Program; Five-Year Review of Work Relative Value Units Under the Physician Fee Schedule

Federal Register 2010, 2011, 2012, 2013, 2014

2011-06-06

... Electrodiagnostic Medicine AAFP American Academy of Family Physicians AAGP American Association for Geriatric... American Academy of Pediatrics AAPM American Academy of Pain Medicine AAPMR American Academy of Physical... Gastroenterological Association AGS American Geriatric Society AK Actinic keratoses AMA American Medical Association...

WE-AB-213-00: Developments in International Medical Physics Collaborations in Africa and Latin America

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

The African Affairs Subcommittee (AA-SC) of the AAPM will present a multi-institutional approach to medical physics support in Africa. Current work to increase the quality of care and level of safety for the medical physics practice in Senegal, Ghana, and Zimbabwe will be presented, along with preliminary projects in Nigeria and Botswana. Because the task of addressing the needs of medical physics in countries across Africa is larger than one entity can accomplish on its own, the AA-SC has taken the approach of joining forces with multiple organizations such as Radiating Hope and TreatSafely (NGO’s), the IAEA, companies like BrainLab,more » Varian and Elekta, medical volunteers and academic institutions such as NYU and Washington University. Elements of current projects include: 1) Distance training and evaluation of the quality of contouring and treatment planning, teaching treatment planning and other subjects, and troubleshooting using modern telecommunications technology in Senegal, Ghana, and Zimbabwe; 2) Assistance in the transition from 2D to 3D in Senegal and Zimbabwe; 3) Assistance in the transition from 3D to IMRT using in-house compensators in Senegal; 4) Modernizing the cancer center in Senegal and increasing safety and; 5) Training on on 3D techniques in Ghana; 6) Assisting a teaching and training radiation oncology center to be built in Zimbabwe; 7) Working with the ISEP Program in Sub-Saharan Africa; 8) Creating instructional videos on linac commissioning; 9) Working on a possible collaboration to train physicists in Nigeria. Building on past achievements, the subcommittee seeks to make a larger impact on the continent, as the number and size of projects increases and more human resources become available. The State of Medical Physics Collaborations and Projects in Latin America Sandra Guzman (Peru) The lack of Medical Physicists (MP) in many Latin American (LA) countries leads to recruitment of professionals with incomplete education. In most LA countries only one MP responsible for each Center is currently mandated. Currently there is a large disparity among MP training programs and there is significant debate about the standards of MP graduate education in many LA countries. There are no commonly recognized academic programs, not enough clinical training sites and clinical training is not typically considered as part of the MP work. Economic pressures and high workloads also impede the creation of more training centers. The increasing need of qualified MPs require establishing a coordinated system of national Education & Training Centers (ETC), to meet the international standards of education and training in Medical Physics. This shortfall calls for support of organizations such as the IOMP, AAPM, ALFIM, IAEA, etc. Examples from various LA countries, as well as some proposed solutions, will be presented. In particular, we will discuss the resources that the AAPM and its members can offer to support regional programs. The ‘Medical Imaging’ physicist in the emerging world: Challenges and opportunities - Caridad Borrás (WGNIMP Chair) While the role of radiation therapy physicists in the emerging world is reasonably well established, the role of medical imaging physicists is not. The only perceived needs in radiology departments are equipment quality control and radiation protection, tasks that can be done by a technologist or a service engineer. To change the situation, the International Basic Safety Standard, which is adopted/adapted world-wide as national radiation protection regulations, states: “For diagnostic radiological procedures and image guided interventional procedures, the requirements of these Standards for medical imaging, calibration, dosimetry and quality assurance, including the acceptance and commissioning of medical radiological equipment, are fulfilled by or under the oversight of, or with the documented advice of a medical physicist, whose degree of involvement is determined by the complexity of the radiological procedures and the associated radiation risks”. Details on how these requirements can be carried out in resource-limited settings will be described. IAEA support to medical physics in Africa and Latin America: achievements and challenges Ahmed Meghzifene (IAEA) Shortage of clinically qualified medical physicists in radiotherapy and imaging, insufficient and inadequate education and training programs, as well as a lack of professional recognition were identified as the main issues to be addressed by the IAEA. The IAEA developed a series of integrated projects aiming specifically at promoting the essential role of medical physicists in health care, developing harmonized guidelines on dosimetry and quality assurance, and supporting education and clinical training programs. The unique feature of the IAEA approach is support it provides for implementation of guidelines and education programs in Member States through its technical cooperation project. The presentation will summarize IAEA support to Latin America and Africa in the field of medical physics and will highlight how the new International Basic Safety Standards are expected to impact the medical physics practice in low and middle income countries. Learning Objectives: Learn about the shortage of qualified Medical Physicists in Africa and Latin America. Understand the reasons of this shortage. Learn about the ways to improve the situation and AAPM role in this process.« less

WE-G-BRC-02: Risk Assessment for HDR Brachytherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mayadev, J.

2016-06-15

Failure Mode and Effects Analysis (FMEA) originated as an industrial engineering technique used for risk management and safety improvement of complex processes. In the context of radiotherapy, the AAPM Task Group 100 advocates FMEA as the framework of choice for establishing clinical quality management protocols. However, there is concern that widespread adoption of FMEA in radiation oncology will be hampered by the perception that implementation of the tool will have a steep learning curve, be extremely time consuming and labor intensive, and require additional resources. To overcome these preconceptions and facilitate the introduction of the tool into clinical practice, themore » medical physics community must be educated in the use of this tool and the ease in which it can be implemented. Organizations with experience in FMEA should share their knowledge with others in order to increase the implementation, effectiveness and productivity of the tool. This session will include a brief, general introduction to FMEA followed by a focus on practical aspects of implementing FMEA for specific clinical procedures including HDR brachytherapy, physics plan review and radiosurgery. A description of common equipment and devices used in these procedures and how to characterize new devices for safe use in patient treatments will be presented. This will be followed by a discussion of how to customize FMEA techniques and templates to one’s own clinic. Finally, cases of common failure modes for specific procedures (described previously) will be shown and recommended intervention methodologies and outcomes reviewed. Learning Objectives: Understand the general concept of failure mode and effect analysis Learn how to characterize new equipment for safety Be able to identify potential failure modes for specific procedures and learn mitigation techniques Be able to customize FMEA examples and templates for use in any clinic.« less

WE-G-BRC-01: Risk Assessment for Radiosurgery

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, G.

2016-06-15

Failure Mode and Effects Analysis (FMEA) originated as an industrial engineering technique used for risk management and safety improvement of complex processes. In the context of radiotherapy, the AAPM Task Group 100 advocates FMEA as the framework of choice for establishing clinical quality management protocols. However, there is concern that widespread adoption of FMEA in radiation oncology will be hampered by the perception that implementation of the tool will have a steep learning curve, be extremely time consuming and labor intensive, and require additional resources. To overcome these preconceptions and facilitate the introduction of the tool into clinical practice, themore » medical physics community must be educated in the use of this tool and the ease in which it can be implemented. Organizations with experience in FMEA should share their knowledge with others in order to increase the implementation, effectiveness and productivity of the tool. This session will include a brief, general introduction to FMEA followed by a focus on practical aspects of implementing FMEA for specific clinical procedures including HDR brachytherapy, physics plan review and radiosurgery. A description of common equipment and devices used in these procedures and how to characterize new devices for safe use in patient treatments will be presented. This will be followed by a discussion of how to customize FMEA techniques and templates to one’s own clinic. Finally, cases of common failure modes for specific procedures (described previously) will be shown and recommended intervention methodologies and outcomes reviewed. Learning Objectives: Understand the general concept of failure mode and effect analysis Learn how to characterize new equipment for safety Be able to identify potential failure modes for specific procedures and learn mitigation techniques Be able to customize FMEA examples and templates for use in any clinic.« less

WE-G-BRC-03: Risk Assessment for Physics Plan Review

DOE Office of Scientific and Technical Information (OSTI.GOV)

Parker, S.

2016-06-15

Failure Mode and Effects Analysis (FMEA) originated as an industrial engineering technique used for risk management and safety improvement of complex processes. In the context of radiotherapy, the AAPM Task Group 100 advocates FMEA as the framework of choice for establishing clinical quality management protocols. However, there is concern that widespread adoption of FMEA in radiation oncology will be hampered by the perception that implementation of the tool will have a steep learning curve, be extremely time consuming and labor intensive, and require additional resources. To overcome these preconceptions and facilitate the introduction of the tool into clinical practice, themore » medical physics community must be educated in the use of this tool and the ease in which it can be implemented. Organizations with experience in FMEA should share their knowledge with others in order to increase the implementation, effectiveness and productivity of the tool. This session will include a brief, general introduction to FMEA followed by a focus on practical aspects of implementing FMEA for specific clinical procedures including HDR brachytherapy, physics plan review and radiosurgery. A description of common equipment and devices used in these procedures and how to characterize new devices for safe use in patient treatments will be presented. This will be followed by a discussion of how to customize FMEA techniques and templates to one’s own clinic. Finally, cases of common failure modes for specific procedures (described previously) will be shown and recommended intervention methodologies and outcomes reviewed. Learning Objectives: Understand the general concept of failure mode and effect analysis Learn how to characterize new equipment for safety Be able to identify potential failure modes for specific procedures and learn mitigation techniques Be able to customize FMEA examples and templates for use in any clinic.« less

A feasibility study to calculate unshielded fetal doses to pregnant patients in 6-MV photon treatments using Monte Carlo methods and anatomically realistic phantoms

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bednarz, Bryan; Xu, X. George

2008-07-15

A Monte Carlo-based procedure to assess fetal doses from 6-MV external photon beam radiation treatments has been developed to improve upon existing techniques that are based on AAPM Task Group Report 36 published in 1995 [M. Stovall et al., Med. Phys. 22, 63-82 (1995)]. Anatomically realistic models of the pregnant patient representing 3-, 6-, and 9-month gestational stages were implemented into the MCNPX code together with a detailed accelerator model that is capable of simulating scattered and leakage radiation from the accelerator head. Absorbed doses to the fetus were calculated for six different treatment plans for sites above the fetusmore » and one treatment plan for fibrosarcoma in the knee. For treatment plans above the fetus, the fetal doses tended to increase with increasing stage of gestation. This was due to the decrease in distance between the fetal body and field edge with increasing stage of gestation. For the treatment field below the fetus, the absorbed doses tended to decrease with increasing gestational stage of the pregnant patient, due to the increasing size of the fetus and relative constant distance between the field edge and fetal body for each stage. The absorbed doses to the fetus for all treatment plans ranged from a maximum of 30.9 cGy to the 9-month fetus to 1.53 cGy to the 3-month fetus. The study demonstrates the feasibility to accurately determine the absorbed organ doses in the mother and fetus as part of the treatment planning and eventually in risk management.« less

Air kerma strength characterization of a GZP6 Cobalt-60 brachytherapy source

PubMed Central

Toossi, Mohammad Taghi Bahreyni; Ghorbani, Mahdi; Mowlavi, Ali Asghar; Taheri, Mojtaba; Layegh, Mohsen; Makhdoumi, Yasha; Meigooni, Ali Soleimani

2010-01-01

Background Task group number 40 (TG-40) of the American Association of Physicists in Medicine (AAPM) has recommended calibration of any brachytherapy source before its clinical use. GZP6 afterloading brachytherapy unit is a 60Co high dose rate (HDR) system recently being used in some of the Iranian radiotherapy centers. Aim In this study air kerma strength (AKS) of 60Co source number three of this unit was estimated by Monte Carlo simulation and in air measurements. Materials and methods Simulation was performed by employing the MCNP-4C Monte Carlo code. Self-absorption of the source core and its capsule were taken into account when calculating air kerma strength. In-air measurements were performed according to the multiple distance method; where a specially designed jig and a 0.6 cm3 Farmer type ionization chamber were used for the measurements. Monte Carlo simulation, in air measurement and GZP6 treatment planning results were compared for primary air kerma strength (as for November 8th 2005). Results Monte Carlo calculated and in air measured air kerma strength were respectively equal to 17240.01 μGym2 h−1 and 16991.83 μGym2 h−1. The value provided by the GZP6 treatment planning system (TPS) was “15355 μGym2 h−1”. Conclusion The calculated and measured AKS values are in good agreement. Calculated-TPS and measured-TPS AKS values are also in agreement within the uncertainties related to our calculation, measurements and those certified by the GZP6 manufacturer. Considering the uncertainties, the TPS value for AKS is validated by our calculations and measurements, however, it is incorporated with a large uncertainty. PMID:24376948

SU-F-T-246: Evaluation of Healthcare Failure Mode And Effect Analysis For Risk Assessment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Harry, T; University of California, San Diego, La Jolla, CA; Manger, R

Purpose: To evaluate the differences between the Veteran Affairs Healthcare Failure Modes and Effect Analysis (HFMEA) and the AAPM Task Group 100 Failure and Effect Analysis (FMEA) risk assessment techniques in the setting of a stereotactic radiosurgery (SRS) procedure were compared respectively. Understanding the differences in the techniques methodologies and outcomes will provide further insight into the applicability and utility of risk assessments exercises in radiation therapy. Methods: HFMEA risk assessment analysis was performed on a stereotactic radiosurgery procedure. A previous study from our institution completed a FMEA of our SRS procedure and the process map generated from this workmore » was used for the HFMEA. The process of performing the HFMEA scoring was analyzed, and the results from both analyses were compared. Results: The key differences between the two risk assessments are the scoring criteria for failure modes and identifying critical failure modes for potential hazards. The general consensus among the team performing the analyses was that scoring for the HFMEA was simpler and more intuitive then the FMEA. The FMEA identified 25 critical failure modes while the HFMEA identified 39. Seven of the FMEA critical failure modes were not identified by the HFMEA and 21 of the HFMEA critical failure modes were not identified by the FMEA. HFMEA as described by the Veteran Affairs provides guidelines on which failure modes to address first. Conclusion: HFMEA is a more efficient model for identifying gross risks in a process than FMEA. Clinics with minimal staff, time and resources can benefit from this type of risk assessment to eliminate or mitigate high risk hazards with nominal effort. FMEA can provide more in depth details but at the cost of elevated effort.« less

SU-F-T-486: A Simple Approach to Performing Light Versus Radiation Field Coincidence Quality Assurance Using An Electronic Portal Imaging Device (EPID)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Herchko, S; Ding, G

2016-06-15

Purpose: To develop an accurate, straightforward, and user-independent method for performing light versus radiation field coincidence quality assurance utilizing EPID images, a simple phantom made of readily-accessible materials, and a free software program. Methods: A simple phantom consisting of a blocking tray, graph paper, and high-density wire was constructed. The phantom was used to accurately set the size of a desired light field and imaged on the electronic portal imaging device (EPID). A macro written for use in ImageJ, a free image processing software, was then use to determine the radiation field size utilizing the high density wires on themore » phantom for a pixel to distance calibration. The macro also performs an analysis on the measured radiation field utilizing the tolerances recommended in the AAPM Task Group #142. To verify the accuracy of this method, radiochromic film was used to qualitatively demonstrate agreement between the film and EPID results, and an additional ImageJ macro was used to quantitatively compare the radiation field sizes measured both with the EPID and film images. Results: The results of this technique were benchmarked against film measurements, which have been the gold standard for testing light versus radiation field coincidence. The agreement between this method and film measurements were within 0.5 mm. Conclusion: Due to the operator dependency associated with tracing light fields and measuring radiation fields by hand when using film, this method allows for a more accurate comparison between the light and radiation fields with minimal operator dependency. Removing the need for radiographic or radiochromic film also eliminates a reoccurring cost and increases procedural efficiency.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

Failure Mode and Effects Analysis (FMEA) originated as an industrial engineering technique used for risk management and safety improvement of complex processes. In the context of radiotherapy, the AAPM Task Group 100 advocates FMEA as the framework of choice for establishing clinical quality management protocols. However, there is concern that widespread adoption of FMEA in radiation oncology will be hampered by the perception that implementation of the tool will have a steep learning curve, be extremely time consuming and labor intensive, and require additional resources. To overcome these preconceptions and facilitate the introduction of the tool into clinical practice, themore » medical physics community must be educated in the use of this tool and the ease in which it can be implemented. Organizations with experience in FMEA should share their knowledge with others in order to increase the implementation, effectiveness and productivity of the tool. This session will include a brief, general introduction to FMEA followed by a focus on practical aspects of implementing FMEA for specific clinical procedures including HDR brachytherapy, physics plan review and radiosurgery. A description of common equipment and devices used in these procedures and how to characterize new devices for safe use in patient treatments will be presented. This will be followed by a discussion of how to customize FMEA techniques and templates to one’s own clinic. Finally, cases of common failure modes for specific procedures (described previously) will be shown and recommended intervention methodologies and outcomes reviewed. Learning Objectives: Understand the general concept of failure mode and effect analysis Learn how to characterize new equipment for safety Be able to identify potential failure modes for specific procedures and learn mitigation techniques Be able to customize FMEA examples and templates for use in any clinic.« less

WE-H-204-00: History Committee Symposium

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

“William D. Coolidge, Inventor of the Modern X-ray Tube” David J. Allard, M.S., CHP - Director, PA DEP Bureau of Radiation Protection William David Coolidge 1873–1975 was a research scientist and inventor of the modern X-ray tube. Besides Roentgen, with his 1895 discovery and subsequent studies of X-rays, perhaps no other individual contributed more to the advancement of X-ray technology than did Coolidge. He was born in Hudson, MA and received his Bachelor of Science degree from MIT in 1896. That same year he went to Europe to study under renowned physicists of the time. Coolidge received his Ph.D. summamore » cum laude from the University of Leipzig in 1899 and soon after joined the staff of MIT. While studying at Leipzig, he met Roentgen. In 1905 he was asked to join the newly established General Electric Research Laboratory in Schenectady, NY. He promptly began fundamental work on the production of ductile tungsten filaments as a replacement for fragile carbon filaments used in incandescent light bulbs. This improved light bulb was brought to market by GE in 1911. It was subsequent application of his tungsten work that led Coolidge to his studies in X ray production. Circa 1910, the state-of-the-art X-ray tube was a “gas tube” or “cold cathode” type tube. These crude X-ray tubes relied on residual gas molecules as a source of electrons for bombardment of low to medium atomic number metal targets. In 1912 Coolidge described the use of tungsten as an improved anode target material for X-ray tubes. Shortly after in 1913 he published a paper in Physical Review describing “A Powerful Roentgen Ray Tube With a Pure Electron Discharge.” This tube used a tungsten filament as a thermionic source of electrons under high vacuum to bombard a tungsten anode target. Great improvements in X-ray tube stability, output and performance were obtained with the “hot cathode” or “Coolidge tube.” With some variation in filament and target geometry, this 100 year old invention is the same basic X-ray tube used today in medicine, research and industry. In 1932 Coolidge became Director of the GE Laboratory, then in 1940 Vice-President and Director of Research. In 1941 he was a member of a small committee, appointed by President Franklin D. Roosevelt, to evaluate the military importance of research on uranium. This committee’s report led to the establishment of the Manhattan Engineering District for nuclear weapons development during WWII. Coolidge lived to be over 100 years old, he had 83 patents to his credit, numerous awards and honorary degrees, and in 1975 was elected to the National Inventor’s Hall of Fame. At the time he was the only inventor to receive this honor in his lifetime. Dr. Coolidge was also the first recipient of the AAPM’s highest science award - named in his honor. From notes of a day-long interview with Coolidge’s son Lawrence in the mid-1990s, previous biographies, publications, books, GE literature, historic photographs, e.g., a wonderful 1874 photo stereoview card with 1 year old baby “Willie Coolidge”, and other artifacts in the author’s collection, this presentation will review Dr. Coolidge’s amazing life, work, accomplishments and awards. “History and Archives Resources at AIP for AAPM and its Members” Gregory A. Good, Ph.D. - Director, AIP Center for History of Physics Melanie J. Mueller, MLIS - Acting Director, AIP Niels Bohr Library & Archives The American Institute of Physics established the Center for History of Physics and the Niels Bohr Library & Archives in the 1960s. Our shared mission is: To preserve and make known the history of the physical sciences. This talk will explore the many ways that AIP’s two history programs support the historical and archival activities of AAPM. Topics will include our ongoing oral history program, web outreach through exhibits and teaching guides, and archiving for AAPM and other Member Societies. We will focus in particular on materials in our collections related to the history of medical physics and to the history of AAPM. We will unveil and demonstrate a new “Archives Portal” that we are designing specifically to be useful to AAPM and its members. Learning Objectives: Study the background of the medical physicist - William David Coolidge Examine the time-line for his success Review the publications conceptualizing his works and progressions Realize what he invented Evaluate the importance of the invention Relate the success to national prominence Uncover how he influenced medical physicists today Find out how he was celebrated by the AAPM View the AIP established Center for History of Physics Consider the significant efforts and vision to preserve the history of medical physics Learn about the Niels Bohr Library & Archives Look back in time at medical physics in the 1960s Unveil and demonstrate a new “Archives Portal” that will be useful to AAPM.« less

WE-H-204-01: William D. Coolidge, Inventor of the Modern X-Ray Tube

DOE Office of Scientific and Technical Information (OSTI.GOV)

Allard, D.

“William D. Coolidge, Inventor of the Modern X-ray Tube” David J. Allard, M.S., CHP - Director, PA DEP Bureau of Radiation Protection William David Coolidge 1873–1975 was a research scientist and inventor of the modern X-ray tube. Besides Roentgen, with his 1895 discovery and subsequent studies of X-rays, perhaps no other individual contributed more to the advancement of X-ray technology than did Coolidge. He was born in Hudson, MA and received his Bachelor of Science degree from MIT in 1896. That same year he went to Europe to study under renowned physicists of the time. Coolidge received his Ph.D. summamore » cum laude from the University of Leipzig in 1899 and soon after joined the staff of MIT. While studying at Leipzig, he met Roentgen. In 1905 he was asked to join the newly established General Electric Research Laboratory in Schenectady, NY. He promptly began fundamental work on the production of ductile tungsten filaments as a replacement for fragile carbon filaments used in incandescent light bulbs. This improved light bulb was brought to market by GE in 1911. It was subsequent application of his tungsten work that led Coolidge to his studies in X ray production. Circa 1910, the state-of-the-art X-ray tube was a “gas tube” or “cold cathode” type tube. These crude X-ray tubes relied on residual gas molecules as a source of electrons for bombardment of low to medium atomic number metal targets. In 1912 Coolidge described the use of tungsten as an improved anode target material for X-ray tubes. Shortly after in 1913 he published a paper in Physical Review describing “A Powerful Roentgen Ray Tube With a Pure Electron Discharge.” This tube used a tungsten filament as a thermionic source of electrons under high vacuum to bombard a tungsten anode target. Great improvements in X-ray tube stability, output and performance were obtained with the “hot cathode” or “Coolidge tube.” With some variation in filament and target geometry, this 100 year old invention is the same basic X-ray tube used today in medicine, research and industry. In 1932 Coolidge became Director of the GE Laboratory, then in 1940 Vice-President and Director of Research. In 1941 he was a member of a small committee, appointed by President Franklin D. Roosevelt, to evaluate the military importance of research on uranium. This committee’s report led to the establishment of the Manhattan Engineering District for nuclear weapons development during WWII. Coolidge lived to be over 100 years old, he had 83 patents to his credit, numerous awards and honorary degrees, and in 1975 was elected to the National Inventor’s Hall of Fame. At the time he was the only inventor to receive this honor in his lifetime. Dr. Coolidge was also the first recipient of the AAPM’s highest science award - named in his honor. From notes of a day-long interview with Coolidge’s son Lawrence in the mid-1990s, previous biographies, publications, books, GE literature, historic photographs, e.g., a wonderful 1874 photo stereoview card with 1 year old baby “Willie Coolidge”, and other artifacts in the author’s collection, this presentation will review Dr. Coolidge’s amazing life, work, accomplishments and awards. “History and Archives Resources at AIP for AAPM and its Members” Gregory A. Good, Ph.D. - Director, AIP Center for History of Physics Melanie J. Mueller, MLIS - Acting Director, AIP Niels Bohr Library & Archives The American Institute of Physics established the Center for History of Physics and the Niels Bohr Library & Archives in the 1960s. Our shared mission is: To preserve and make known the history of the physical sciences. This talk will explore the many ways that AIP’s two history programs support the historical and archival activities of AAPM. Topics will include our ongoing oral history program, web outreach through exhibits and teaching guides, and archiving for AAPM and other Member Societies. We will focus in particular on materials in our collections related to the history of medical physics and to the history of AAPM. We will unveil and demonstrate a new “Archives Portal” that we are designing specifically to be useful to AAPM and its members. Learning Objectives: Study the background of the medical physicist - William David Coolidge Examine the time-line for his success Review the publications conceptualizing his works and progressions Realize what he invented Evaluate the importance of the invention Relate the success to national prominence Uncover how he influenced medical physicists today Find out how he was celebrated by the AAPM View the AIP established Center for History of Physics Consider the significant efforts and vision to preserve the history of medical physics Learn about the Niels Bohr Library & Archives Look back in time at medical physics in the 1960s Unveil and demonstrate a new “Archives Portal” that will be useful to AAPM.« less

Diagnostic ultrasound exposure in man.

PubMed

Gramiak, R

1975-09-01

In his review of the AAPM statement on ultrasound, the author feels that allowing "some" research or demonstration on normal persons in the face of cautionary statements on as yet unknown side effects is an inconsistent position. The use of videotapes and the development of simulators hacked by data banks are offered in place of tissue phantoms.

Careers in Medical Physics and the American Association of Physicists in Medicine

NASA Astrophysics Data System (ADS)

Amols, Howard

2006-03-01

The American Association of Physicists in Medicine (AAPM), a member society of the AIP is the largest professional society of medical physicists in the world with nearly 5700 members. Members operate in medical centers, university and community hospitals, research laboratories, industry, and private practice. Medical physics specialties include radiation therapy physics, medical diagnostic and imaging physics, nuclear medicine physics, and medical radiation safety. The majority of AAPM members is based in hospital departments of radiation oncology or radiology and provide technical support for patient diagnosis and treatment in a clinical environment. Job functions include support of clinical care, calibration and quality assurance of medical devices such as linear accelerators for cancer therapy, CT, PET, MRI, and other diagnostic imaging devices, research, and teaching. Pathways into a career in medical physics require an advanced degree in medical physics, physics, engineering, or closely related field, plus clinical training in one or more medical physics specialties (radiation therapy physics, imaging physics, or radiation safety). Most clinically based medical physicists also obtain certification from the American Board of Radiology, and some states require licensure as well.

TU-A-17A-01: Memorial to Benjamin M. Galkin - Memorial Lecture

DOE Office of Scientific and Technical Information (OSTI.GOV)

Suntharalingam, N

2014-06-15

This past year Medical Physics lost one of its active members, Benjamin M. Galkin. Ben Galkin was a Past-Treasurer of the AAPM. During his leadership role he played an important part in Securing membership, for the AAPM, in the American Institute of physics. As Treasurer he was also a prime mover in starting the journal, Medical Physics, and served as its business manager in the formative years.Ben Galkin received his Masters Degree at Columbia University in New York, under the mentorship of Dr. Edith Quimby, one of the pioneer Hospital Radiation Physicists in the country. He started his professional careermore » at Jefferson Hospital in Philadelphia, joining Robert Gorson, and remained there until retirement. He served as the institution’s Radiation Safety Officer throughout his career. His research interest was Breast Imaging. He held joint faculty appointments in the Department of Radiology and the Department of Radiation Therapy and Nuclear Medicine, rising up to the rank of Full professor. He was a well respected teacher for the residents in Radiology.« less

Addendum to the AAPM's TG-51 protocol for clinical reference dosimetry of high-energy photon beams

DOE Office of Scientific and Technical Information (OSTI.GOV)

McEwen, Malcolm, E-mail: malcolm.mcewen@nrc-cnrc.gc.ca; DeWerd, Larry; Ibbott, Geoffrey

2014-04-15

An addendum to the AAPM's TG-51 protocol for the determination of absorbed dose to water in megavoltage photon beams is presented. This addendum continues the procedure laid out in TG-51 but new k{sub Q} data for photon beams, based on Monte Carlo simulations, are presented and recommendations are given to improve the accuracy and consistency of the protocol's implementation. The components of the uncertainty budget in determining absorbed dose to water at the reference point are introduced and the magnitude of each component discussed. Finally, the consistency of experimental determination of N{sub D,w} coefficients is discussed. It is expected thatmore » the implementation of this addendum will be straightforward, assuming that the user is already familiar with TG-51. The changes introduced by this report are generally minor, although new recommendations could result in procedural changes for individual users. It is expected that the effort on the medical physicist's part to implement this addendum will not be significant and could be done as part of the annual linac calibration.« less

Air-kerma strength determination of a new directional (103)Pd source.

PubMed

Aima, Manik; Reed, Joshua L; DeWerd, Larry A; Culberson, Wesley S

2015-12-01

A new directional (103)Pd planar source array called a CivaSheet™ has been developed by CivaTech Oncology, Inc., for potential use in low-dose-rate (LDR) brachytherapy treatments. The array consists of multiple individual polymer capsules called CivaDots, containing (103)Pd and a gold shield that attenuates the radiation on one side, thus defining a hot and cold side. This novel source requires new methods to establish a source strength metric. The presence of gold material in such close proximity to the active (103)Pd region causes the source spectrum to be significantly different than the energy spectra of seeds normally used in LDR brachytherapy treatments. In this investigation, the authors perform air-kerma strength (S(K)) measurements, develop new correction factors for these measurements based on an experimentally verified energy spectrum, and test the robustness of transferring S(K) to a well-type ionization chamber. S(K) measurements were performed with the variable-aperture free-air chamber (VAFAC) at the University of Wisconsin Medical Radiation Research Center. Subsequent measurements were then performed in a well-type ionization chamber. To realize the quantity S(K) from a directional source with gold material present, new methods and correction factors were considered. Updated correction factors were calculated using the MCNP 6 Monte Carlo code in order to determine S(K) with the presence of gold fluorescent energy lines. In addition to S(K) measurements, a low-energy high-purity germanium (HPGe) detector was used to experimentally verify the calculated spectrum, a sodium iodide (NaI) scintillating counter was used to verify the azimuthal and polar anisotropy, and a well-type ionization chamber was used to test the feasibility of disseminating S(K) values for a directional source within a cylindrically symmetric measurement volume. The UW VAFAC was successfully used to measure the S(K) of four CivaDots with reproducibilities within 0.3%. Monte Carlo methods were used to calculate the UW VAFAC correction factors and the calculated spectrum emitted from a CivaDot was experimentally verified with HPGe detector measurements. The well-type ionization chamber showed minimal variation in response (<1.5%) as a function of source positioning angle, indicating that an American Association of Physicists in Medicine (AAPM) Accredited Dosimetry Calibration Laboratory calibrated well chamber would be a suitable device to transfer an S(K)-based calibration to a clinical user. S(K) per well-chamber ionization current ratios were consistent among the four dots measured. Additionally, the measurements and predictions of anisotropy show uniform emission within the solid angle of the VAFAC, which demonstrates the robustness of the S(K) measurement approach. This characterization of a new (103)Pd directional brachytherapy source helps to establish calibration methods that could ultimately be used in the well-established AAPM Task Group 43 formalism. Monte Carlo methods accurately predict the changes in the energy spectrum caused by the fluorescent x-rays produced in the gold shield.

Air-kerma strength determination of a new directional 103Pd source

PubMed Central

Reed, Joshua L.; DeWerd, Larry A.; Culberson, Wesley S.

2015-01-01

Purpose: A new directional 103Pd planar source array called a CivaSheet™ has been developed by CivaTech Oncology, Inc., for potential use in low-dose-rate (LDR) brachytherapy treatments. The array consists of multiple individual polymer capsules called CivaDots, containing 103Pd and a gold shield that attenuates the radiation on one side, thus defining a hot and cold side. This novel source requires new methods to establish a source strength metric. The presence of gold material in such close proximity to the active 103Pd region causes the source spectrum to be significantly different than the energy spectra of seeds normally used in LDR brachytherapy treatments. In this investigation, the authors perform air-kerma strength (SK) measurements, develop new correction factors for these measurements based on an experimentally verified energy spectrum, and test the robustness of transferring SK to a well-type ionization chamber. Methods: SK measurements were performed with the variable-aperture free-air chamber (VAFAC) at the University of Wisconsin Medical Radiation Research Center. Subsequent measurements were then performed in a well-type ionization chamber. To realize the quantity SK from a directional source with gold material present, new methods and correction factors were considered. Updated correction factors were calculated using the mcnp 6 Monte Carlo code in order to determine SK with the presence of gold fluorescent energy lines. In addition to SK measurements, a low-energy high-purity germanium (HPGe) detector was used to experimentally verify the calculated spectrum, a sodium iodide (NaI) scintillating counter was used to verify the azimuthal and polar anisotropy, and a well-type ionization chamber was used to test the feasibility of disseminating SK values for a directional source within a cylindrically symmetric measurement volume. Results: The UW VAFAC was successfully used to measure the SK of four CivaDots with reproducibilities within 0.3%. Monte Carlo methods were used to calculate the UW VAFAC correction factors and the calculated spectrum emitted from a CivaDot was experimentally verified with HPGe detector measurements. The well-type ionization chamber showed minimal variation in response (<1.5%) as a function of source positioning angle, indicating that an American Association of Physicists in Medicine (AAPM) Accredited Dosimetry Calibration Laboratory calibrated well chamber would be a suitable device to transfer an SK-based calibration to a clinical user. SK per well-chamber ionization current ratios were consistent among the four dots measured. Additionally, the measurements and predictions of anisotropy show uniform emission within the solid angle of the VAFAC, which demonstrates the robustness of the SK measurement approach. Conclusions: This characterization of a new 103Pd directional brachytherapy source helps to establish calibration methods that could ultimately be used in the well-established AAPM Task Group 43 formalism. Monte Carlo methods accurately predict the changes in the energy spectrum caused by the fluorescent x-rays produced in the gold shield. PMID:26632069

A systematic evaluation of the dose-rate constant determined by photon spectrometry for 21 different models of low-energy photon-emitting brachytherapy sources.

PubMed

Chen, Zhe Jay; Nath, Ravinder

2010-10-21

The aim of this study was to perform a systematic comparison of the dose-rate constant (Λ) determined by the photon spectrometry technique (PST) with the consensus value ((CON)Λ) recommended by the American Association of Physicists in Medicine (AAPM) for 21 low-energy photon-emitting interstitial brachytherapy sources. A total of 63 interstitial brachytherapy sources (21 different models with 3 sources per model) containing either (125)I (14 models), (103)Pd (6 models) or (131)Cs (1 model) were included in this study. A PST described by Chen and Nath (2007 Med. Phys. 34 1412-30) was used to determine the dose-rate constant ((PST)Λ) for each source model. Source-dependent variations in (PST)Λ were analyzed systematically against the spectral characteristics of the emitted photons and the consensus values recommended by the AAPM brachytherapy subcommittee. The values of (PST)Λ for the encapsulated sources of (103)Pd, (125)I and (131)Cs varied from 0.661 to 0.678 cGyh(-1) U(-1), 0.959 to 1.024 cGyh(-1)U(-1) and 1.066 to 1.073 cGyh(-1)U(-1), respectively. The relative variation in (PST)Λ among the six (103)Pd source models, caused by variations in photon attenuation and in spatial distributions of radioactivity among the source models, was less than 3%. Greater variations in (PST)Λ were observed among the 14 (125)I source models; the maximum relative difference was over 6%. These variations were caused primarily by the presence of silver in some (125)I source models and, to a lesser degree, by the variations in photon attenuation and in spatial distribution of radioactivity among the source models. The presence of silver generates additional fluorescent x-rays with lower photon energies which caused the (PST)Λ value to vary from 0.959 to 1.019 cGyh(-1)U(-1) depending on the amount of silver used by a given source model. For those (125)I sources that contain no silver, their (PST)Λ was less variable and had values within 1% of 1.024 cGyh(-1)U(-1). For the 16 source models that currently have an AAPM recommended (CON)Λ value, the agreement between (PST)Λ and (CON)Λ was less than 2% for 15 models and was 2.6% for 1 (103)Pd source model. Excellent agreement between (PST)Λ and (CON)Λ was observed for all source models that currently have an AAPM recommended consensus dose-rate constant value. These results demonstrate that the PST is an accurate and robust technique for the determination of the dose-rate constant for low-energy brachytherapy sources.

A round-robin gamma stereotactic radiosurgery dosimetry interinstitution comparison of calibration protocols

DOE Office of Scientific and Technical Information (OSTI.GOV)

Drzymala, R. E., E-mail: drzymala@wustl.edu; Alvarez, P. E.; Bednarz, G.

2015-11-15

Purpose: Absorbed dose calibration for gamma stereotactic radiosurgery is challenging due to the unique geometric conditions, dosimetry characteristics, and nonstandard field size of these devices. Members of the American Association of Physicists in Medicine (AAPM) Task Group 178 on Gamma Stereotactic Radiosurgery Dosimetry and Quality Assurance have participated in a round-robin exchange of calibrated measurement instrumentation and phantoms exploring two approved and two proposed calibration protocols or formalisms on ten gamma radiosurgery units. The objectives of this study were to benchmark and compare new formalisms to existing calibration methods, while maintaining traceability to U.S. primary dosimetry calibration laboratory standards. Methods:more » Nine institutions made measurements using ten gamma stereotactic radiosurgery units in three different 160 mm diameter spherical phantoms [acrylonitrile butadiene styrene (ABS) plastic, Solid Water, and liquid water] and in air using a positioning jig. Two calibrated miniature ionization chambers and one calibrated electrometer were circulated for all measurements. Reference dose-rates at the phantom center were determined using the well-established AAPM TG-21 or TG-51 dose calibration protocols and using two proposed dose calibration protocols/formalisms: an in-air protocol and a formalism proposed by the International Atomic Energy Agency (IAEA) working group for small and nonstandard radiation fields. Each institution’s results were normalized to the dose-rate determined at that institution using the TG-21 protocol in the ABS phantom. Results: Percentages of dose-rates within 1.5% of the reference dose-rate (TG-21 + ABS phantom) for the eight chamber-protocol-phantom combinations were the following: 88% for TG-21, 70% for TG-51, 93% for the new IAEA nonstandard-field formalism, and 65% for the new in-air protocol. Averages and standard deviations for dose-rates over all measurements relative to the TG-21 + ABS dose-rate were 0.999 ± 0.009 (TG-21), 0.991 ± 0.013 (TG-51), 1.000 ± 0.009 (IAEA), and 1.009 ± 0.012 (in-air). There were no statistically significant differences (i.e., p > 0.05) between the two ionization chambers for the TG-21 protocol applied to all dosimetry phantoms. The mean results using the TG-51 protocol were notably lower than those for the other dosimetry protocols, with a standard deviation 2–3 times larger. The in-air protocol was not statistically different from TG-21 for the A16 chamber in the liquid water or ABS phantoms (p = 0.300 and p = 0.135) but was statistically different from TG-21 for the PTW chamber in all phantoms (p = 0.006 for Solid Water, 0.014 for liquid water, and 0.020 for ABS). Results of IAEA formalism were statistically different from TG-21 results only for the combination of the A16 chamber with the liquid water phantom (p = 0.017). In the latter case, dose-rates measured with the two protocols differed by only 0.4%. For other phantom-ionization-chamber combinations, the new IAEA formalism was not statistically different from TG-21. Conclusions: Although further investigation is needed to validate the new protocols for other ionization chambers, these results can serve as a reference to quantitatively compare different calibration protocols and ionization chambers if a particular method is chosen by a professional society to serve as a standardized calibration protocol.« less

Dosimetric characterization and output verification for conical brachytherapy surface applicators. Part I. Electronic brachytherapy source

PubMed Central

Fulkerson, Regina K.; Micka, John A.; DeWerd, Larry A.

2014-01-01

Purpose: Historically, treatment of malignant surface lesions has been achieved with linear accelerator based electron beams or superficial x-ray beams. Recent developments in the field of brachytherapy now allow for the treatment of surface lesions with specialized conical applicators placed directly on the lesion. Applicators are available for use with high dose rate (HDR) 192Ir sources, as well as electronic brachytherapy sources. Part I of this paper will discuss the applicators used with electronic brachytherapy sources; Part II will discuss those used with HDR 192Ir sources. Although the use of these applicators has gained in popularity, the dosimetric characteristics including depth dose and surface dose distributions have not been independently verified. Additionally, there is no recognized method of output verification for quality assurance procedures with applicators like these. Existing dosimetry protocols available from the AAPM bookend the cross-over characteristics of a traditional brachytherapy source (as described by Task Group 43) being implemented as a low-energy superficial x-ray beam (as described by Task Group 61) as observed with the surface applicators of interest. Methods: This work aims to create a cohesive method of output verification that can be used to determine the dose at the treatment surface as part of a quality assurance/commissioning process for surface applicators used with HDR electronic brachytherapy sources (Part I) and 192Ir sources (Part II). Air-kerma rate measurements for the electronic brachytherapy sources were completed with an Attix Free-Air Chamber, as well as several models of small-volume ionization chambers to obtain an air-kerma rate at the treatment surface for each applicator. Correction factors were calculated using MCNP5 and EGSnrc Monte Carlo codes in order to determine an applicator-specific absorbed dose to water at the treatment surface from the measured air-kerma rate. Additionally, relative dose measurements of the surface dose distributions and characteristic depth dose curves were completed in-phantom. Results: Theoretical dose distributions and depth dose curves were generated for each applicator and agreed well with the measured values. A method of output verification was created that allows users to determine the applicator-specific dose to water at the treatment surface based on a measured air-kerma rate. Conclusions: The novel output verification methods described in this work will reduce uncertainties in dose delivery for treatments with these kinds of surface applicators, ultimately improving patient care. PMID:24506635

TU-D-201-03: Results of a Survey On the Implementation of the TG-51 Protocol and Associated Addendum On Reference Dosimetry of External Beams

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, G; Muir, B; Culberson, W

Purpose: The working group on the review and extension of the TG-51 protocol (WGTG51) collected data from American Association of Physicists in Medicine (AAPM) members with respect to their current TG-51 and associated addendum usage in the interest of considering future protocol addenda and guidance on reference dosimetry best practices. This study reports an overview of this survey on dosimetry of external beams. Methods: Fourteen survey questions were developed by WGTG51 and released in November 2015. The questions collected information on reference dosimetry, beam quality specification, and ancillary calibration equipment. Results: Of the 190 submissions completed worldwide (U.S. 70%), 83%more » were AAPM members. Of the respondents, 33.5% implemented the TG-51 addendum, with the maximum calibration difference for any photon beam, with respect to the original TG-51 protocol, being <1% for 97.4% of responses. One major finding is that 81.8% of respondents used the same cylindrical ionization chamber for photon and electron dosimetry, implying that many clinics are foregoing the use of parallel-plate chambers. Other evidence suggests equivalent dosimetric results can be obtained with both cylindrical and parallel-plate chambers in electron beams. This, combined with users comfort with cylindrical chambers for electrons will likely impact recommendations put forward in an upcoming electron beam addendum to the TG-51 protocol. Data collected on ancillary equipment showed 58.2% (45.0%) of the thermometers (barometers) in use for beam calibration had NIST traceable calibration certificates, but 48.4% (42.7%) were never recalibrated. Conclusion: This survey provides a snapshot of TG-51 external beam reference dosimetry practice in radiotherapy centers. Findings demonstrate the rapid take-up of the TG-51 photon beam addendum and raise issues for the WGTG51 to focus on going forward, including guidelines on ancillary equipment and the choice of chamber for electron beam dosimetry.« less

Testing the quality of images for permanent magnet desktop MRI systems using specially designed phantoms.

PubMed

Qiu, Jianfeng; Wang, Guozhu; Min, Jiao; Wang, Xiaoyan; Wang, Pengcheng

2013-12-21

Our aim was to measure the performance of desktop magnetic resonance imaging (MRI) systems using specially designed phantoms, by testing imaging parameters and analysing the imaging quality. We designed multifunction phantoms with diameters of 18 and 60 mm for desktop MRI scanners in accordance with the American Association of Physicists in Medicine (AAPM) report no. 28. We scanned the phantoms with three permanent magnet 0.5 T desktop MRI systems, measured the MRI image parameters, and analysed imaging quality by comparing the data with the AAPM criteria and Chinese national standards. Image parameters included: resonance frequency, high contrast spatial resolution, low contrast object detectability, slice thickness, geometrical distortion, signal-to-noise ratio (SNR), and image uniformity. The image parameters of three desktop MRI machines could be measured using our specially designed phantoms, and most parameters were in line with MRI quality control criterion, including: resonance frequency, high contrast spatial resolution, low contrast object detectability, slice thickness, geometrical distortion, image uniformity and slice position accuracy. However, SNR was significantly lower than in some references. The imaging test and quality control are necessary for desktop MRI systems, and should be performed with the applicable phantom and corresponding standards.

Determination of the Sensibility Factors for TLD-100 Powder on the Energy of X-Ray of 50, 250 kVp; 192Ir, 137Cs and 60Co

DOE Office of Scientific and Technical Information (OSTI.GOV)

Loaiza, Sandra P.; Alvarez, Jose T.

2006-09-08

TLD-100 powder is calibrated in terms of absorbed dose to water Dw, using the protocols AAPM TG61, AAPM TG43 and IAEA-TRS 398, for the energy of RX 50, 250 kVp, 137Cs and 60Co respectively. The calibration curves, TLD Response R versus Dw, are fitted by weighted least square by a quadratic polynomials; which are validated with the lack of fit and the Anderson-Darling normality test. The slope of these curves corresponds to the sensibility factor: Fs R/DW, [Fs] = nC Gy-1. The expanded uncertainties U's for these factors are obtained from the ANOVA tables. Later, the Fs' values are interpolatedmore » using the effective energy hvefec for the 192Ir. The SSDL sent a set of capsules with powder TLD-100 for two Hospitals. These irradiated them a nominal dose of Dw = 2 Gy. The results determined at SSDL are: for the Hospital A the Dw is overestimated in order to 4.8% and the Hospital B underestimates it in the range from -1.4% to -17.5%.« less

TU-D-201-01: 2016 Economics Update

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fontenot, J; Fuss, W

The purpose of this session is to introduce attendees to the healthcare reimbursement system and how it applies to the clinical work of a medical physicist. This will include general information about the different categories of payers and payees, how work is described by CPT codes, and how various payers set values for this work in different clinical settings. 2016 is another year of significant changes to the payment system. This presentation will describe the work encompassed in these codes and will give attendees an overview of the changes for 2016 as they apply to radiation oncology. Finally, some insightmore » into what can be expected during 2017 will be presented. This includes what information is typically released by the Centers for Medicaid and Medicare Services (CMS) during the year and how we as an organization respond. This will include ways members can interact with the AAPM professional economics committee and other resources members may find helpful. Learning objectives1) Basics of how Medicare is structured and how reimbursement rates are set.2) Basic understanding of proposed changes to the 2016 Medicare rules.3) Describe economics and policy resources that are available from the AAPM and how to interact with the professional economics committee.« less

WE-A-201-02: Modern Statistical Modeling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Niemierko, A.

Chris Marshall: Memorial Introduction Donald Edmonds Herbert Jr., or Don to his colleagues and friends, exemplified the “big tent” vision of medical physics, specializing in Applied Statistics and Dynamical Systems theory. He saw, more clearly than most, that “Making models is the difference between doing science and just fooling around [ref Woodworth, 2004]”. Don developed an interest in chemistry at school by “reading a book” - a recurring theme in his story. He was awarded a Westinghouse Science scholarship and attended the Carnegie Institute of Technology (later Carnegie Mellon University) where his interest turned to physics and led to amore » BS in Physics after transfer to Northwestern University. After (voluntary) service in the Navy he earned his MS in Physics from the University of Oklahoma, which led him to Johns Hopkins University in Baltimore to pursue a PhD. The early death of his wife led him to take a salaried position in the Physics Department of Colorado College in Colorado Springs so as to better care for their young daughter. There, a chance invitation from Dr. Juan del Regato to teach physics to residents at the Penrose Cancer Hospital introduced him to Medical Physics, and he decided to enter the field. He received his PhD from the University of London (UK) under Prof. Joseph Rotblat, where I first met him, and where he taught himself statistics. He returned to Penrose as a clinical medical physicist, also largely self-taught. In 1975 he formalized an evolving interest in statistical analysis as Professor of Radiology and Head of the Division of Physics and Statistics at the College of Medicine of the University of South Alabama in Mobile, AL where he remained for the rest of his career. He also served as the first Director of their Bio-Statistics and Epidemiology Core Unit working in part on a sickle-cell disease. After retirement he remained active as Professor Emeritus. Don served for several years as a consultant to the Nuclear Regulatory Commission and may be remembered for his critique of the National Academy of Sciences BEIR III report (stating that their methodology “imposes a Delphic quality to the .. risk estimates”.) This led to his appointment as a member of the BEIR V committee. Don presented refresher courses at the AAPM, ASTRO and RSNA meetings and was active in the AAPM as a member or chair of several committees. He was the principal author of AAPM Report 43, which is essentially a critique of established clinical studies prior to 1992. He was co-editor of the Proceedings of many symposia on Time, Dose and Fractionation held in Madison, Wisconsin. He received the AAPM lifetime Achievement award in 2004. Don’s second wife of 46 years, Ann, predeceased him and he is survived by daughters Hillary and Emily, son John and two grandsons. Don was a true gentleman with a unique and erudite writing style illuminated by pithy quotations. If he had a fault it was, perhaps, that he did not realize how much smarter he was than the rest of us. This presentation draws heavily on a biography and video interview in the History and Heritage section of the AAPM website. The quote is his own. Andrzej Niemierko: Statistical modeling plays an essential role in modern medicine for quantitative evaluation of the effect of treatment. This session will feature an overview of statistical modeling techniques used for analyzing the many types of research data and an exploration of recent advances in new statistical modeling methodologies. Learning Objectives: To learn basics of statistical modeling methodology. To discuss statistical models that are frequently used in radiation oncology To discuss advanced modern statistical modeling methods and applications.« less

WE-A-201-00: Anne and Donald Herbert Distinguished Lectureship On Modern Statistical Modeling

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

Chris Marshall: Memorial Introduction Donald Edmonds Herbert Jr., or Don to his colleagues and friends, exemplified the “big tent” vision of medical physics, specializing in Applied Statistics and Dynamical Systems theory. He saw, more clearly than most, that “Making models is the difference between doing science and just fooling around [ref Woodworth, 2004]”. Don developed an interest in chemistry at school by “reading a book” - a recurring theme in his story. He was awarded a Westinghouse Science scholarship and attended the Carnegie Institute of Technology (later Carnegie Mellon University) where his interest turned to physics and led to amore » BS in Physics after transfer to Northwestern University. After (voluntary) service in the Navy he earned his MS in Physics from the University of Oklahoma, which led him to Johns Hopkins University in Baltimore to pursue a PhD. The early death of his wife led him to take a salaried position in the Physics Department of Colorado College in Colorado Springs so as to better care for their young daughter. There, a chance invitation from Dr. Juan del Regato to teach physics to residents at the Penrose Cancer Hospital introduced him to Medical Physics, and he decided to enter the field. He received his PhD from the University of London (UK) under Prof. Joseph Rotblat, where I first met him, and where he taught himself statistics. He returned to Penrose as a clinical medical physicist, also largely self-taught. In 1975 he formalized an evolving interest in statistical analysis as Professor of Radiology and Head of the Division of Physics and Statistics at the College of Medicine of the University of South Alabama in Mobile, AL where he remained for the rest of his career. He also served as the first Director of their Bio-Statistics and Epidemiology Core Unit working in part on a sickle-cell disease. After retirement he remained active as Professor Emeritus. Don served for several years as a consultant to the Nuclear Regulatory Commission and may be remembered for his critique of the National Academy of Sciences BEIR III report (stating that their methodology “imposes a Delphic quality to the .. risk estimates”.) This led to his appointment as a member of the BEIR V committee. Don presented refresher courses at the AAPM, ASTRO and RSNA meetings and was active in the AAPM as a member or chair of several committees. He was the principal author of AAPM Report 43, which is essentially a critique of established clinical studies prior to 1992. He was co-editor of the Proceedings of many symposia on Time, Dose and Fractionation held in Madison, Wisconsin. He received the AAPM lifetime Achievement award in 2004. Don’s second wife of 46 years, Ann, predeceased him and he is survived by daughters Hillary and Emily, son John and two grandsons. Don was a true gentleman with a unique and erudite writing style illuminated by pithy quotations. If he had a fault it was, perhaps, that he did not realize how much smarter he was than the rest of us. This presentation draws heavily on a biography and video interview in the History and Heritage section of the AAPM website. The quote is his own. Andrzej Niemierko: Statistical modeling plays an essential role in modern medicine for quantitative evaluation of the effect of treatment. This session will feature an overview of statistical modeling techniques used for analyzing the many types of research data and an exploration of recent advances in new statistical modeling methodologies. Learning Objectives: To learn basics of statistical modeling methodology. To discuss statistical models that are frequently used in radiation oncology To discuss advanced modern statistical modeling methods and applications.« less

WE-A-201-01: Memorial Introduction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Marshall, C.

Chris Marshall: Memorial Introduction Donald Edmonds Herbert Jr., or Don to his colleagues and friends, exemplified the “big tent” vision of medical physics, specializing in Applied Statistics and Dynamical Systems theory. He saw, more clearly than most, that “Making models is the difference between doing science and just fooling around [ref Woodworth, 2004]”. Don developed an interest in chemistry at school by “reading a book” - a recurring theme in his story. He was awarded a Westinghouse Science scholarship and attended the Carnegie Institute of Technology (later Carnegie Mellon University) where his interest turned to physics and led to amore » BS in Physics after transfer to Northwestern University. After (voluntary) service in the Navy he earned his MS in Physics from the University of Oklahoma, which led him to Johns Hopkins University in Baltimore to pursue a PhD. The early death of his wife led him to take a salaried position in the Physics Department of Colorado College in Colorado Springs so as to better care for their young daughter. There, a chance invitation from Dr. Juan del Regato to teach physics to residents at the Penrose Cancer Hospital introduced him to Medical Physics, and he decided to enter the field. He received his PhD from the University of London (UK) under Prof. Joseph Rotblat, where I first met him, and where he taught himself statistics. He returned to Penrose as a clinical medical physicist, also largely self-taught. In 1975 he formalized an evolving interest in statistical analysis as Professor of Radiology and Head of the Division of Physics and Statistics at the College of Medicine of the University of South Alabama in Mobile, AL where he remained for the rest of his career. He also served as the first Director of their Bio-Statistics and Epidemiology Core Unit working in part on a sickle-cell disease. After retirement he remained active as Professor Emeritus. Don served for several years as a consultant to the Nuclear Regulatory Commission and may be remembered for his critique of the National Academy of Sciences BEIR III report (stating that their methodology “imposes a Delphic quality to the .. risk estimates”.) This led to his appointment as a member of the BEIR V committee. Don presented refresher courses at the AAPM, ASTRO and RSNA meetings and was active in the AAPM as a member or chair of several committees. He was the principal author of AAPM Report 43, which is essentially a critique of established clinical studies prior to 1992. He was co-editor of the Proceedings of many symposia on Time, Dose and Fractionation held in Madison, Wisconsin. He received the AAPM lifetime Achievement award in 2004. Don’s second wife of 46 years, Ann, predeceased him and he is survived by daughters Hillary and Emily, son John and two grandsons. Don was a true gentleman with a unique and erudite writing style illuminated by pithy quotations. If he had a fault it was, perhaps, that he did not realize how much smarter he was than the rest of us. This presentation draws heavily on a biography and video interview in the History and Heritage section of the AAPM website. The quote is his own. Andrzej Niemierko: Statistical modeling plays an essential role in modern medicine for quantitative evaluation of the effect of treatment. This session will feature an overview of statistical modeling techniques used for analyzing the many types of research data and an exploration of recent advances in new statistical modeling methodologies. Learning Objectives: To learn basics of statistical modeling methodology. To discuss statistical models that are frequently used in radiation oncology To discuss advanced modern statistical modeling methods and applications.« less

Absorbed dose to water based dosimetry versus air kerma based dosimetry for high-energy photon beams: an experimental study.

PubMed

Palmans, Hugo; Nafaa, Laila; De, Jans Jo; Gillis, Sofie; Hoornaert, Marie-Thérèse; Martens, Chantal; Piessens, Marleen; Thierens, Hubert; Van der Plaetsen, Ann; Vynckier, Stefaan

2002-02-07

In recent years, a change has been proposed from air kerma based reference dosimetry to absorbed dose based reference dosimetry for all radiotherapy beams of ionizing radiation. In this paper, a dosimetry study is presented in which absorbed dose based dosimetry using recently developed formalisms was compared with air kerma based dosimetry using older formalisms. Three ionization chambers of each of three different types were calibrated in terms of absorbed dose to water and air kerma and sent to five hospitals. There, reference dosimetry with all the chambers was performed in a total of eight high-energy clinical photon beams. The selected chamber types were the NE2571, the PTW-30004 and the Wellhöfer-FC65G (previously Wellhöfer-IC70). Having a graphite wall, they exhibit a stable volume and the presence of an aluminium electrode ensures the robustness of these chambers. The data were analysed with the most important recommendations for clinical dosimetry: IAEA TRS-398, AAPM TG-51, IAEA TRS-277, NCS report-2 (presently recommended in Belgium) and AAPM TG-21. The necessary conversion factors were taken from those protocols, or calculated using the data in the different protocols if data for a chamber type are lacking. Polarity corrections were within 0.1% for all chambers in all beams. Recombination corrections were consistent with theoretical predictions, did not vary within a chamber type and only slightly between different chamber types. The maximum chamber-to-chamber variations of the dose obtained with the different formalisms within the same chamber type were between 0.2% and 0.6% for the NE2571, between 0.2% and 0.6% for the PTW-30004 and 0.1% and 0.3% for the Wellhöfer-FC65G for the different beams. The absorbed dose results for the NE2571 and Wellhöfer-FC65G chambers were in good agreement for all beams and all formalisms. The PTW-30004 chambers gave a small but systematically higher result compared to the result for the NE2571 chambers (on the average 0.1% for IAEA TRS-277, 0.3% for NCS report-2 and AAPM TG-21 and 0.4% for IAEA TRS-398 and AAPM TG-51). Within the air kerma based protocols, the results obtained with the TG-21 protocol were 0.4-0.8% higher mainly due to the differences in the data used. Both absorbed dose to water based formalisms resulted in consistent values within 0.3%. The change from old to new formalisms is discussed together with the traceability of calibration factors obtained at the primary absorbed dose and air kerma standards in the reference beams (60Co). For the particular situation in Belgium (calibrations at the Laboratory for Standard Dosimetry of Ghent) the change amounts to 0.1-0.6%. This is similar to the magnitude of the change determined in other countries.

Technical assessment of a cone-beam CT scanner for otolaryngology imaging: image quality, dose, and technique protocols.

PubMed

Xu, J; Reh, D D; Carey, J P; Mahesh, M; Siewerdsen, J H

2012-08-01

As cone-beam CT (CBCT) systems dedicated to various imaging specialties proliferate, technical assessment grounded in imaging physics is important to ensuring that image quality and radiation dose are quantified, understood, and justified. This paper involves technical assessment of a new CBCT scanner (CS 9300, Carestream Health, Rochester, NY) dedicated to imaging of the ear and sinuses for applications in otolaryngology-head and neck surgery (OHNS). The results guided evaluation of technique protocols to minimize radiation dose in a manner sufficient for OHNS imaging tasks. The technical assessment focused on the imaging performance and radiation dose for each of seven technique protocols recommended by the manufacturer: three sinus protocols and four ear (temporal bone) protocols. Absolute dose was measured using techniques adapted from AAPM Task Group Report No. 111, involving three stacked 16 cm diameter acrylic cylinders (CTDI phantoms) and a 0.6 cm(3) Farmer ionization chamber to measure central and peripheral dose. The central dose (D(o)) was also measured as a function of longitudinal position (z) within and beyond the primary radiation field to assess, for example, out-of-field dose to the neck. Signal-difference-to-noise ratio (SDNR) and Hounsfield unit (HU) accuracy were assessed in a commercially available quality assurance phantom (CATPHAN module CTP404, The Phantom Laboratory, Greenwich, NY) and a custom phantom with soft-tissue-simulating plastic inserts (Gammex RMI, Madison, WI). Spatial resolution was assessed both qualitatively (a line-pair pattern, CATPHAN module CTP528) and quantitatively (modulation transfer function, MTF, measured with a wire phantom). Imaging performance pertinent to various OHNS imaging tasks was qualitatively assessed using an anthropomorphic phantom as evaluated by two experienced OHNS specialists. The technical assessment motivated a variety of modifications to the manufacturer-specified protocols to provide reduced radiation dose without compromising pertinent task-based imaging performance. The revised protocols yielded D(o) ranging 2.9-5.7 mGy, representing a ∼30% reduction in dose from the original technique chart. Out-of-field dose was ∼10% of D(o) at a distance of ∼8 cm from the field edge. Soft-tissue contrast resolution was fairly limited (water-brain SDNR ∼0.4-0.7) while high-contrast performance was reasonably good (SDNR ∼2-4 for a polystyrene insert in the CATPHAN). The scanner does not demonstrate (or claim to provide) accurate HU and exhibits a systematic error in CT number that could potentially be addressed by further calibration. The spatial resolution is ∼10-16 lp∕cm as assessed in a line-pair phantom, with MTF exceeding 10% out to ∼20 lp∕cm. Qualitative assessment by expert readers suggested limited soft-tissue visibility but excellent high-contrast (bone) visualization with isotropic spatial resolution suitable to a broad spectrum of pertinent sinus and temporal bone imaging tasks. The CBCT scanner provided spatial and contrast resolution suitable to visualization of high-contrast morphology in sinus, maxillofacial, and otologic imaging applications. Rigorous technical assessment guided revision of technique protocols to reduce radiation dose while maintaining image quality sufficient for pertinent imaging tasks. The scanner appears well suited to high-contrast sinus and temporal bone imaging at doses comparable to or less than that reported for conventional diagnostic CT of the head.

SU-E-T-467: Monte Carlo Dosimetric Study of the New Flexisource Co-60 High Dose Rate Source.

PubMed

Vijande, J; Granero, D; Perez-Calatayud, J; Ballester, F

2012-06-01

Recently, a new HDR 60Co brachytherapy source, Flexisource Co-60, has been developed (Nucletron B.V.). This study aims to obtain quality dosimetric data for this source for its use in clinical practice as required by AAPM and ESTRO. Penelope2008 and GEANT4 Monte Carlo codes were used to dosimetrically characterize this source. Water composition and mass density was that recommended by AAPM. Due to the high energy of the 60Co, dose for small distances cannot be approximated by collisional kerma. Therefore, we have considered absorbed dose to water for r<0.75 cm and collisional kerma from 0.75 0.8 cm and up to 2% closer to the source. Using Penelope2008 and GEANT4, an average of Î> = 1.085±0.003 cGy/(h U) (with k = 1, Type A uncertainties) was obtained. Dose rate constant, radial dose function and anisotropy functions for the Flexisource Co-60 are compared with published data for other Co-60 sources. Dosimetric data are provided for the new Flexisource Co-60 source not studied previously in the literature. Using the data provided by this study in the treatment planning systems, it can be used in clinical practice. This project has been funded by Nucletron BV. © 2012 American Association of Physicists in Medicine.

SU-E-T-781: Using An Electronic Portal Imaging Device (EPID) for Correlating Linac Photon Beam Energies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yaddanapudi, S; Cai, B; Sun, B

2015-06-15

Purpose: Electronic portal imaging devices (EPIDs) have proven to be useful for measuring several parameters of interest in linear accelerator (linac) quality assurance (QA). The purpose of this project was to evaluate the feasibility of using EPIDs for determining linac photon beam energies. Methods: Two non-clinical Varian TrueBeam linacs (Varian Medical Systems, Palo Alto, CA) with 6MV and 10MV photon beams were used to perform the measurements. The linacs were equipped with an amorphous silicon based EPIDs (aSi1000) that were used for the measurements. We compared the use of flatness versus percent depth dose (PDD) for predicting changes in linacmore » photon beam energy. PDD was measured in 1D water tank (Sun Nuclear Corporation, Melbourne FL) and the profiles were measured using 2D ion-chamber array (IC-Profiler, Sun Nuclear) and the EPID. Energy changes were accomplished by varying the bending magnet current (BMC). The evaluated energies conformed with the AAPM TG142 tolerance of ±1% change in PDD. Results: BMC changes correlating with a ±1% change in PDD corresponded with a change in flatness of ∼1% to 2% from baseline values on the EPID. IC Profiler flatness values had the same correlation. We observed a similar trend for the 10MV beam energy changes. Our measurements indicated a strong correlation between changes in linac photon beam energy and changes in flatness. For all machines and energies, beam energy changes produced change in the uniformity (AAPM TG-142), varying from ∼1% to 2.5%. Conclusions: EPID image analysis of beam profiles can be used to determine linac photon beam energy changes. Flatness-based metrics or uniformity as defined by AAPM TG-142 were found to be more sensitive to linac photon beam energy changes than PDD. Research funding provided by Varian Medical Systems. Dr. Sasa Mutic receives compensation for providing patient safety training services from Varian Medical Systems, the sponsor of this study.« less

Air-kerma strength determination of a new directional {sup 103}Pd source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aima, Manik, E-mail: aima@wisc.edu; Reed, Joshua L.; DeWerd, Larry A.

2015-12-15

Purpose: A new directional {sup 103}Pd planar source array called a CivaSheet™ has been developed by CivaTech Oncology, Inc., for potential use in low-dose-rate (LDR) brachytherapy treatments. The array consists of multiple individual polymer capsules called CivaDots, containing {sup 103}Pd and a gold shield that attenuates the radiation on one side, thus defining a hot and cold side. This novel source requires new methods to establish a source strength metric. The presence of gold material in such close proximity to the active {sup 103}Pd region causes the source spectrum to be significantly different than the energy spectra of seeds normallymore » used in LDR brachytherapy treatments. In this investigation, the authors perform air-kerma strength (S{sub K}) measurements, develop new correction factors for these measurements based on an experimentally verified energy spectrum, and test the robustness of transferring S{sub K} to a well-type ionization chamber. Methods: S{sub K} measurements were performed with the variable-aperture free-air chamber (VAFAC) at the University of Wisconsin Medical Radiation Research Center. Subsequent measurements were then performed in a well-type ionization chamber. To realize the quantity S{sub K} from a directional source with gold material present, new methods and correction factors were considered. Updated correction factors were calculated using the MCNP 6 Monte Carlo code in order to determine S{sub K} with the presence of gold fluorescent energy lines. In addition to S{sub K} measurements, a low-energy high-purity germanium (HPGe) detector was used to experimentally verify the calculated spectrum, a sodium iodide (NaI) scintillating counter was used to verify the azimuthal and polar anisotropy, and a well-type ionization chamber was used to test the feasibility of disseminating S{sub K} values for a directional source within a cylindrically symmetric measurement volume. Results: The UW VAFAC was successfully used to measure the S{sub K} of four CivaDots with reproducibilities within 0.3%. Monte Carlo methods were used to calculate the UW VAFAC correction factors and the calculated spectrum emitted from a CivaDot was experimentally verified with HPGe detector measurements. The well-type ionization chamber showed minimal variation in response (<1.5%) as a function of source positioning angle, indicating that an American Association of Physicists in Medicine (AAPM) Accredited Dosimetry Calibration Laboratory calibrated well chamber would be a suitable device to transfer an S{sub K}-based calibration to a clinical user. S{sub K} per well-chamber ionization current ratios were consistent among the four dots measured. Additionally, the measurements and predictions of anisotropy show uniform emission within the solid angle of the VAFAC, which demonstrates the robustness of the S{sub K} measurement approach. Conclusions: This characterization of a new {sup 103}Pd directional brachytherapy source helps to establish calibration methods that could ultimately be used in the well-established AAPM Task Group 43 formalism. Monte Carlo methods accurately predict the changes in the energy spectrum caused by the fluorescent x-rays produced in the gold shield.« less

Biological risks of medical irradiations: Medical physics monograph 5

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fullerton, G.D., Kopp, D.T.; Waggener, R.G.; Webster, E.W.

1980-01-01

This book is the fifth in a series of monographs by the American Association of Physicists in Medicine (AAPM) and is a compendium of papers presented at an AAPM regional symposium conducted in San Antonio in July 1980. The book is divided into three sections: (1) biological fundamentals of ionizing radiation, (2) risk evaluation and reduction in three principle radiologic subspecialties (diagnostic radiology, nuclear medicine and radiation therapy), and (3) medical-legal implications. The first section includes a historical review of radiation biology, including a discussion of somatic and genetic effects and statistical approaches to risk estimates. The section on riskmore » evaluation and reduction includes a good review of the units of exposure and activity including the international (SI) system employing the gray, becquerel, and seivert that respectively replace the rad, Curie, and rem. The unavoidable problem of legal responsibility and liability is the subject of the third, and last, section of the monograph. A chapter summarizing the legal history of medical irradiation also includes a glossary of pertinent legal terms. Recent court decisions that impact upon the clinical use of radiation are presented and discussed as well as proposed changes in federal guidelines that could have a large impact on the practice of medicine in general and radiology in particular. (JMT)« less

Dose heterogeneity correction for low-energy brachytherapy sources using dual-energy CT images

NASA Astrophysics Data System (ADS)

Mashouf, S.; Lechtman, E.; Lai, P.; Keller, B. M.; Karotki, A.; Beachey, D. J.; Pignol, J. P.

2014-09-01

Permanent seed implant brachytherapy is currently used for adjuvant radiotherapy of early stage prostate and breast cancer patients. The current standard for calculation of dose around brachytherapy sources is based on the AAPM TG-43 formalism, which generates the dose in a homogeneous water medium. Recently, AAPM TG-186 emphasized the importance of accounting for tissue heterogeneities. We have previously reported on a methodology where the absorbed dose in tissue can be obtained by multiplying the dose, calculated by the TG-43 formalism, by an inhomogeneity correction factor (ICF). In this work we make use of dual energy CT (DECT) images to extract ICF parameters. The advantage of DECT over conventional CT is that it eliminates the need for tissue segmentation as well as assignment of population based atomic compositions. DECT images of a heterogeneous phantom were acquired and the dose was calculated using both TG-43 and TG-43 × \\text{ICF} formalisms. The results were compared to experimental measurements using Gafchromic films in the mid-plane of the phantom. For a seed implant configuration of 8 seeds spaced 1.5 cm apart in a cubic structure, the gamma passing score for 2%/2 mm criteria improved from 40.8% to 90.5% when ICF was applied to TG-43 dose distributions.

Report on the American Association of Medical Physics Undergraduate Fellowship Programs

PubMed Central

Avery, Stephen; Gueye, Paul; Sandison, George A.

2013-01-01

The American Association of Physicists in Medicine (AAPM) sponsors two summer undergraduate research programs to attract top performing undergraduate students into graduate studies in medical physics: the Summer Undergraduate Fellowship Program (SUFP) and the Minority Undergraduate Summer Experience (MUSE). Undergraduate research experience (URE) is an effective tool to encourage students to pursue graduate degrees. The SUFP and MUSE are the only medical physics URE programs. From 2001 to 2012, 148 fellowships have been awarded and a total of $608,000 has been dispersed to fellows. This paper reports on the history, participation, and status of the programs. A review of surveys of past fellows is presented. Overall, the fellows and mentors are very satisfied with the program. The efficacy of the programs is assessed by four metrics: entry into a medical physics graduate program, board certification, publications, and AAPM involvement. Sixty‐five percent of past fellow respondents decided to pursue a graduate degree in medical physics as a result of their participation in the program. Seventy percent of respondents are currently involved in some educational or professional aspect of medical physics. Suggestions for future enhancements to better track and maintain contact with past fellows, expand funding sources, and potentially combine the programs are presented. PACS number: 01.10.Hx PMID:23318397

DOE Office of Scientific and Technical Information (OSTI.GOV)

Scaduto, DA; Hu, Y-H; Zhao, W

Purpose: Spatial resolution in digital breast tomosynthesis (DBT) is affected by inherent/binned detector resolution, oblique entry of x-rays, and focal spot size/motion; the limited angular range further limits spatial resolution in the depth-direction. While DBT is being widely adopted clinically, imaging performance metrics and quality control protocols have not been standardized. AAPM Task Group 245 on Tomosynthesis Quality Control has been formed to address this deficiency. Methods: Methods of measuring spatial resolution are evaluated using two prototype quality control phantoms for DBT. Spatial resolution in the detector plane is measured in projection and reconstruction domains using edge-spread function (ESF), point-spreadmore » function (PSF) and modulation transfer function (MTF). Spatial resolution in the depth-direction and effective slice thickness are measured in the reconstruction domain using slice sensitivity profile (SSP) and artifact spread function (ASF). An oversampled PSF in the depth-direction is measured using a 50 µm angulated tungsten wire, from which the MTF is computed. Object-dependent PSF is derived and compared with ASF. Sensitivity of these measurements to phantom positioning, imaging conditions and reconstruction algorithms is evaluated. Results are compared from systems of varying acquisition geometry (9–25 projections over 15–60°). Dependence of measurements on feature size is investigated. Results: Measurements of spatial resolution using PSF and LSF are shown to depend on feature size; depth-direction spatial resolution measurements are shown to similarly depend on feature size for ASF, though deconvolution with an object function removes feature size-dependence. A slanted wire may be used to measure oversampled PSFs, from which MTFs may be computed for both in-plane and depth-direction resolution. Conclusion: Spatial resolution measured using PSF is object-independent with sufficiently small object; MTF is object-independent. Depth-direction spatial resolution may be measured directly using MTF or indirectly using ASF or SSP as surrogate measurements. While MTF is object-independent, it is invalid for nonlinear reconstructions.« less

TH-AB-201-01: A Feasibility Study of Independent Dose Verification for CyberKnife

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sato, A; Noda, T; Keduka, Y

2016-06-15

Purpose: CyberKnife irradiation is composed of tiny-size, multiple and intensity-modulated beams compared to conventional linacs. Few of the publications for Independent dose calculation verification for CyberKnife have been reported. In this study, we evaluated the feasibility of independent dose verification for CyberKnife treatment as Secondary check. Methods: The followings were measured: test plans using some static and single beams, clinical plans in a phantom and using patient’s CT. 75 patient plans were collected from several treatment sites of brain, lung, liver and bone. In the test plans and the phantom plans, a pinpoint ion-chamber measurement was performed to assess dosemore » deviation for a treatment planning system (TPS) and an independent verification program of Simple MU Analysis (SMU). In the clinical plans, dose deviation between the SMU and the TPS was performed. Results: In test plan, the dose deviations were 3.3±4.5%, and 4.1±4.4% for the TPS and the SMU, respectively. In the phantom measurements for the clinical plans, the dose deviations were −0.2±3.6% for the TPS and −2.3±4.8% for the SMU. In the clinical plans using the patient’s CT, the dose deviations were −3.0±2.1% (Mean±1SD). The systematic difference was partially derived from inverse square law and penumbra calculation. Conclusion: The independent dose calculation for CyberKnife shows −3.0±4.2% (Mean±2SD) and our study, the confidence limit was achieved within 5% of the tolerance level from AAPM task group 114 for non-IMRT treatment. Thus, it may be feasible to use independent dose calculation verification for CyberKnife treatment as the secondary check. This research is partially supported by Japan Agency for Medical Research and Development (AMED)« less

Radiotherapy dose verification on a customised head and neck perspex phantom

NASA Astrophysics Data System (ADS)

Eng, K. Y.; Kandaiya, S.; Yahaya, N. Z.

2017-05-01

IMRT dose planned for head and neck radiotherapy was verified using a customised acrylic head-and-neck phantom. The dosimeters used were calibrated Gafchromic EBT2 film and metal-oxide-semiconductor-field-effect-transistor (MOSFET). Target volumes (TV) and organs-at-risk (OAR) which were previously contoured by an oncologist on selected nasopharynx (NPC) patients were transferred to this phantom by an image fusion procedure. Three radiotherapy plans were done: Plan1 with 7-fields intensity-modulated radiotherapy (IMRT) of prescribed dose 70 Gy using 33 fractions; Plan2 with 7-fields IMRT plan at 70 Gy and 35 fractions; and Plan3 which was a mid-plane-dose (MPD) plan of 66 Gy at 33 fractions. The dose maps were first verified using MapCheck2 by SNC-PatientTM software. The passing rates from gamma analysis were 97.7% (Plan1), 93.1% (Plan2) and 100% (Plan3). Percentage difference between Treatment Planning System (TPS) calculated dose and MOSFET measured dose was comparatively higher than those from EBT2. Calculated dose and EBT2 measured doses showed differences of within the range of ±3% for TV and <±10% for OARs. However MOSFET had differences of within the range of ±6% for TV and within the range of ±10% for OARs between measured and planned doses. An overdose treatment may occur as TPS calculated doses were lower than the measured doses in these plans. This may be due to the effects of leaf leakage, leaf scatter and photon backscatter into the measuring tools (Pawlicki et al., 1999 and Ma et al., 2000). More IMRT plans have to be studied to validate this conclusion. However, the dose measurements were still within the 10% tolerance (AAPM Task Group 119). In conclusion, both GafchromicEBT2 film and MOSFET are suitable for IMRT radiotherapy dosimetry.

The first MICCAI challenge on PET tumor segmentation.

PubMed

Hatt, Mathieu; Laurent, Baptiste; Ouahabi, Anouar; Fayad, Hadi; Tan, Shan; Li, Laquan; Lu, Wei; Jaouen, Vincent; Tauber, Clovis; Czakon, Jakub; Drapejkowski, Filip; Dyrka, Witold; Camarasu-Pop, Sorina; Cervenansky, Frédéric; Girard, Pascal; Glatard, Tristan; Kain, Michael; Yao, Yao; Barillot, Christian; Kirov, Assen; Visvikis, Dimitris

2018-02-01

Automatic functional volume segmentation in PET images is a challenge that has been addressed using a large array of methods. A major limitation for the field has been the lack of a benchmark dataset that would allow direct comparison of the results in the various publications. In the present work, we describe a comparison of recent methods on a large dataset following recommendations by the American Association of Physicists in Medicine (AAPM) task group (TG) 211, which was carried out within a MICCAI (Medical Image Computing and Computer Assisted Intervention) challenge. Organization and funding was provided by France Life Imaging (FLI). A dataset of 176 images combining simulated, phantom and clinical images was assembled. A website allowed the participants to register and download training data (n = 19). Challengers then submitted encapsulated pipelines on an online platform that autonomously ran the algorithms on the testing data (n = 157) and evaluated the results. The methods were ranked according to the arithmetic mean of sensitivity and positive predictive value. Sixteen teams registered but only four provided manuscripts and pipeline(s) for a total of 10 methods. In addition, results using two thresholds and the Fuzzy Locally Adaptive Bayesian (FLAB) were generated. All competing methods except one performed with median accuracy above 0.8. The method with the highest score was the convolutional neural network-based segmentation, which significantly outperformed 9 out of 12 of the other methods, but not the improved K-Means, Gaussian Model Mixture and Fuzzy C-Means methods. The most rigorous comparative study of PET segmentation algorithms to date was carried out using a dataset that is the largest used in such studies so far. The hierarchy amongst the methods in terms of accuracy did not depend strongly on the subset of datasets or the metrics (or combination of metrics). All the methods submitted by the challengers except one demonstrated good performance with median accuracy scores above 0.8. Copyright © 2017 Elsevier B.V. All rights reserved.

Comparison between TG-51 and TG-21: Calibration of photon and electron beams in water using cylindrical chambers.

PubMed

Cho, S H; Lowenstein, J R; Balter, P A; Wells, N H; Hanson, W F

2000-01-01

A new calibration protocol, developed by the AAPM Task Group 51 (TG-51) to replace the TG-21 protocol, is based on an absorbed-dose to water standard and calibration factor (N(D,w)), while the TG-21 protocol is based on an exposure (or air-kerma) standard and calibration factor (N(x)). Because of differences between these standards and the two protocols, the results of clinical reference dosimetry based on TG-51 may be somewhat different from those based on TG-21. The Radiological Physics Center has conducted a systematic comparison between the two protocols, in which photon and electron beam outputs following both protocols were compared under identical conditions. Cylindrical chambers used in this study were selected from the list given in the TG-51 report, covering the majority of current manufacturers. Measured ratios between absorbed-dose and air-kerma calibration factors, derived from the standards traceable to the NIST, were compared with calculated values using the TG-21 protocol. The comparison suggests that there is roughly a 1% discrepancy between measured and calculated ratios. This discrepancy may provide a reasonable measure of possible changes between the absorbed-dose to water determined by TG-51 and that determined by TG-21 for photon beam calibrations. The typical change in a 6 MV photon beam calibration following the implementation of the TG-51 protocol was about 1%, regardless of the chamber used, and the change was somewhat smaller for an 18 MV photon beam. On the other hand, the results for 9 and 16 MeV electron beams show larger changes up to 2%, perhaps because of the updated electron stopping power data used for the TG-51 protocol, in addition to the inherent 1% discrepancy presented in the calibration factors. The results also indicate that the changes may be dependent on the electron energy.

MO-D-213-02: Quality Improvement Through a Failure Mode and Effects Analysis of Pediatric External Beam Radiotherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gray, J; Lukose, R; Bronson, J

2015-06-15

Purpose: To conduct a failure mode and effects analysis (FMEA) as per AAPM Task Group 100 on clinical processes associated with teletherapy, and the development of mitigations for processes with identified high risk. Methods: A FMEA was conducted on clinical processes relating to teletherapy treatment plan development and delivery. Nine major processes were identified for analysis. These steps included CT simulation, data transfer, image registration and segmentation, treatment planning, plan approval and preparation, and initial and subsequent treatments. Process tree mapping was utilized to identify the steps contained within each process. Failure modes (FM) were identified and evaluated with amore » scale of 1–10 based upon three metrics: the severity of the effect, the probability of occurrence, and the detectability of the cause. The analyzed metrics were scored as follows: severity – no harm = 1, lethal = 10; probability – not likely = 1, certainty = 10; detectability – always detected = 1, undetectable = 10. The three metrics were combined multiplicatively to determine the risk priority number (RPN) which defined the overall score for each FM and the order in which process modifications should be deployed. Results: Eighty-nine procedural steps were identified with 186 FM accompanied by 193 failure effects with 213 potential causes. Eighty-one of the FM were scored with a RPN > 10, and mitigations were developed for FM with RPN values exceeding ten. The initial treatment had the most FM (16) requiring mitigation development followed closely by treatment planning, segmentation, and plan preparation with fourteen each. The maximum RPN was 400 and involved target delineation. Conclusion: The FMEA process proved extremely useful in identifying previously unforeseen risks. New methods were developed and implemented for risk mitigation and error prevention. Similar to findings reported for adult patients, the process leading to the initial treatment has an associated high risk.« less

SU-F-T-267: A Clarkson-Based Independent Dose Verification for the Helical Tomotherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nagata, H; Juntendo University, Hongo, Tokyo; Hongo, H

2016-06-15

Purpose: There have been few reports for independent dose verification for Tomotherapy. We evaluated the accuracy and the effectiveness of an independent dose verification system for the Tomotherapy. Methods: Simple MU Analysis (SMU, Triangle Product, Ishikawa, Japan) was used as the independent verification system and the system implemented a Clarkson-based dose calculation algorithm using CT image dataset. For dose calculation in the SMU, the Tomotherapy machine-specific dosimetric parameters (TMR, Scp, OAR and MLC transmission factor) were registered as the machine beam data. Dose calculation was performed after Tomotherapy sinogram from DICOM-RT plan information was converted to the information for MUmore » and MLC location at more segmented control points. The performance of the SMU was assessed by a point dose measurement in non-IMRT and IMRT plans (simple target and mock prostate plans). Subsequently, 30 patients’ treatment plans for prostate were compared. Results: From the comparison, dose differences between the SMU and the measurement were within 3% for all cases in non-IMRT plans. In the IMRT plan for the simple target, the differences (Average±1SD) were −0.70±1.10% (SMU vs. TPS), −0.40±0.10% (measurement vs. TPS) and −1.20±1.00% (measurement vs. SMU), respectively. For the mock prostate, the differences were −0.40±0.60% (SMU vs. TPS), −0.50±0.90% (measurement vs. TPS) and −0.90±0.60% (measurement vs. SMU), respectively. For patients’ plans, the difference was −0.50±2.10% (SMU vs. TPS). Conclusion: A Clarkson-based independent dose verification for the Tomotherapy can be clinically available as a secondary check with the similar tolerance level of AAPM Task group 114. This research is partially supported by Japan Agency for Medical Research and Development (AMED)« less

Multi-institutional evaluation of end-to-end protocol for IMRT/VMAT treatment chains utilizing conventional linacs.

PubMed

Loughery, Brian; Knill, Cory; Silverstein, Evan; Zakjevskii, Viatcheslav; Masi, Kathryn; Covington, Elizabeth; Snyder, Karen; Song, Kwang; Snyder, Michael

2018-03-20

We conducted a multi-institutional assessment of a recently developed end-to-end monthly quality assurance (QA) protocol for external beam radiation therapy treatment chains. This protocol validates the entire treatment chain against a baseline to detect the presence of complex errors not easily found in standard component-based QA methods. Participating physicists from 3 institutions ran the end-to-end protocol on treatment chains that include Imaging and Radiation Oncology Core (IROC)-credentialed linacs. Results were analyzed in the form of American Association of Physicists in Medicine (AAPM) Task Group (TG)-119 so that they may be referenced by future test participants. Optically stimulated luminescent dosimeter (OSLD), EBT3 radiochromic film, and A1SL ion chamber readings were accumulated across 10 test runs. Confidence limits were calculated to determine where 95% of measurements should fall. From calculated confidence limits, 95% of measurements should be within 5% error for OSLDs, 4% error for ionization chambers, and 4% error for (96% relative gamma pass rate) radiochromic film at 3% agreement/3 mm distance to agreement. Data were separated by institution, model of linac, and treatment protocol (intensity-modulated radiation therapy [IMRT] vs volumetric modulated arc therapy [VMAT]). A total of 97% of OSLDs, 98% of ion chambers, and 93% of films were within the confidence limits; measurements were found outside these limits by a maximum of 4%, < 1%, and < 1%, respectively. Data were consistent despite institutional differences in OSLD reading equipment and radiochromic film calibration techniques. Results from this test may be used by clinics for data comparison. Areas of improvement were identified in the end-to-end protocol that can be implemented in an updated version. The consistency of our data demonstrates the reproducibility and ease-of-use of such tests and suggests a potential role for their use in broad end-to-end QA initiatives. Copyright © 2018 American Association of Medical Dosimetrists. Published by Elsevier Inc. All rights reserved.

Dosimetric characterizations of GZP6 60Co high dose rate brachytherapy sources: application of superimposition method

PubMed Central

Bahreyni Toossi, Mohammad Taghi; Ghorbani, Mahdi; Mowlavi, Ali Asghar; Meigooni, Ali Soleimani

2012-01-01

Background Dosimetric characteristics of a high dose rate (HDR) GZP6 Co-60 brachytherapy source have been evaluated following American Association of Physicists in MedicineTask Group 43U1 (AAPM TG-43U1) recommendations for their clinical applications. Materials and methods MCNP-4C and MCNPX Monte Carlo codes were utilized to calculate dose rate constant, two dimensional (2D) dose distribution, radial dose function and 2D anisotropy function of the source. These parameters of this source are compared with the available data for Ralstron 60Co and microSelectron192Ir sources. Besides, a superimposition method was developed to extend the obtained results for the GZP6 source No. 3 to other GZP6 sources. Results The simulated value for dose rate constant for GZP6 source was 1.104±0.03 cGyh-1U-1. The graphical and tabulated radial dose function and 2D anisotropy function of this source are presented here. The results of these investigations show that the dosimetric parameters of GZP6 source are comparable to those for the Ralstron source. While dose rate constant for the two 60Co sources are similar to that for the microSelectron192Ir source, there are differences between radial dose function and anisotropy functions. Radial dose function of the 192Ir source is less steep than both 60Co source models. In addition, the 60Co sources are showing more isotropic dose distribution than the 192Ir source. Conclusions The superimposition method is applicable to produce dose distributions for other source arrangements from the dose distribution of a single source. The calculated dosimetric quantities of this new source can be introduced as input data to the GZP6 treatment planning system (TPS) and to validate the performance of the TPS. PMID:23077455

TU-F-CAMPUS-T-05: Dose Escalation to Biological Tumor Volumes of Prostate Cancer Patients Using Gold Nanoparticles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jermoumi, M; Ngwa, W; Department of Radiation Oncology, Dana Farber Cancer Insitute, Brigham and Women’s Hospital, Harvard Medical, Boston, MA

2015-06-15

Purpose: Studies have shown that radiation boosting could help reduce prostate cancer (PCa) recurrence. Biological tumor volumes (BTV) are a high priority for such radiation boosting. The purpose of this study is to investigate the potential of radiation boosting of real patient BTVs using gold nanoparticles (GNP) released from gold-loaded brachytherapy spacers (GBS) during brachytherapy. Methods: The BTVs of 12 patients having prostate adenocarcinoma identified with positron emission tomography (PET) and CT scanner using C-11 labeled tracer [11C]acetate were investigated. The initial GNP concentration and time to achieve a dose enhancement effect (DEF) of 2 was simulated using the freelymore » downloadable software RAID APP. The investigations were carried out for low dose rate (LDR) brachytherapy sources (BTS) described in AAPM Task Group report 43: Cs-131, I-125, and Pd-103. In first case, we used 7 mg/g and 18 mg/g of GNP initial concentrations to estimate the time needed for released GNP to achieve a DEF of 2 for the different BTS, and compare with clinically relevant treatment times. In second case, we calculated the initial concentration of GNPs needed to achieve a DEF of 2 during the time the BTS would typically deliver 50%, 70% and 90% of the total dose. Results: For an initial concentration of 18 mg/g, when using Cs-131, and Pd-103, a DEF of 2 could only be achieved for BTV of 3.3 cm3 and 1 cm3 respectively. Meanwhile a DEF of 2 could be achieved for all 12 BTVs when using I-125. To achieve a DEF of 2 for all patients using Cs-131 and Pd-103, much higher initial concentrations would have to be used than have been typically employed in pre-clinical studies. Conclusion: The I-125 is the most viable BTS that can be employed with GBS to guide dose painting treatment planning for localized PCa.« less

SU-F-T-270: A Technique for Modeling a Diode Array Into the TPS for Lung SBRT Patient Specific QA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Curley, C; Leventouri, T; Ouhib, Z

2016-06-15

Purpose: To accurately match the treatment planning system (TPS) with the measurement environment, where quality assurance (QA) devices are used to collect data, for lung Stereotactic Body Radiation Therapy (SBRT) patient specific QA. Incorporation of heterogeneities is also studied. Methods: Dual energy computerized tomography (DECT) and single energy computerized tomography (SECT) were used to model phantoms incorporating a 2-D diode array into the TPS. A water-equivalent and a heterogeneous phantom (simulating the thoracic region of a patient) were studied. Monte Carlo and pencil beam planar dose distributions were compared to measured distributions. Composite and individual fields were analyzed for normallymore » incident and planned gantry angle deliveries. γ- analysis was used with criteria 3% 3mm, 2% 2mm, and 1% 1mm. Results: The Monte Carlo calculations for the DECT resulted in improved agreements with the diode array for 46.4% of the fields at 3% 3mm, 85.7% at 2% 2mm, and 92.9% at 1% 1mm.For the SECT, the Monte Carlo calculations gave no agreement for the same γ-analysis criteria. Pencil beam calculations resulted in lower agreements with the diode array in the TPS. The DECT showed improvements for 14.3% of the fields at 3% 3mm and 2% 2mm, and 28.6% at 1% 1mm.In SECT comparisons, 7.1% of the fields at 3% 3mm, 10.7% at 2% 2mm, and 17.9% at 1% 1mm showed improved agreements with the diode array. Conclusion: This study demonstrates that modeling the diode array in the TPS is viable using DECT with Monte Carlo for patient specific lung SBRT QA. As recommended by task groups (e.g. TG 65, TG 101, TG 244) of the American Association of Physicists in Medicine (AAPM), pencil beam algorithms should be avoided in the presence of heterogeneous materials, including a diode array.« less

SU-E-J-126: Respiratory Gating Quality Assurance: A Simple Method to Achieve Millisecond Temporal Resolution

DOE Office of Scientific and Technical Information (OSTI.GOV)

McCabe, B; Wiersma, R

Purpose: Low temporal latency between a gating on/off signal and a linac beam on/off during respiratory gating is critical for patient safety. Although, a measurement of temporal lag is recommended by AAPM Task Group 142 for commissioning and annual quality assurance, there currently exists no published method. Here we describe a simple, inexpensive, and reliable method to precisely measure gating lag at millisecond resolutions. Methods: A Varian Real-time Position Management™ (RPM) gating simulator with rotating disk was modified with a resistive flex sensor (Spectra Symbol) attached to the gating box platform. A photon diode was placed at machine isocenter. Outputmore » signals of the flex sensor and diode were monitored with a multichannel oscilloscope (Tektronix™ DPO3014). Qualitative inspection of the gating window/beam on synchronicity were made by setting the linac to beam on/off at end-expiration, and the oscilloscope's temporal window to 100 ms to visually examine if the on/off timing was within the recommended 100-ms tolerance. Quantitative measurements were made by saving the signal traces and analyzing in MatLab™. The on and off of the beam signal were located and compared to the expected gating window (e.g. 40% to 60%). Four gating cycles were measured and compared. Results: On a Varian TrueBeam™ STx linac with RPM gating software, the average difference in synchronicity at beam on and off for four cycles was 14 ms (3 to 30 ms) and 11 ms (2 to 32 ms), respectively. For a Varian Clinac™ 21EX the average difference at beam on and off was 127 ms (122 to 133 ms) and 46 ms (42 to 49 ms), respectively. The uncertainty in the synchrony difference was estimated at ±6 ms. Conclusion: This new gating QA method is easy to implement and allows for fast qualitative inspection and quantitative measurements for commissioning and TG-142 annual QA measurements.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rodriguez, M; Bartolac, S; Rezaee, M

Purpose: To examine the agreement between absorbed doses calculated by RayStation treatment planning algorithm to those measured with gafchromic film and ion chamber when the photon beam is perturbed by attenuation or lateral scatter of lung material. Methods: A gafchromic EBT2 film was placed in the center of a 30×30×20 cm{sup 3} solid water phantom with a 5 cm lung slab placed at 10 cm depth. The film was irradiated at SSD = 100 cm with a 6 MV photon beam, 10×10 and 5×5 cm{sup 2} field sizes and with the beam parallel to the film and lung slab. Amore » CT was performed to the phantom arrangement for RayStation dose calculation. The films were scanned in an Epson 10000X flatbed scanner and analyzed using the red channel, 16 bits, 76 dpi. PDD curves at the central axis and profiles at dmax were also measured in water using a CC13 (0.13 CC) ion chamber. Measurements and calculation of PDD curves at the central axis and profiles at dmax and 20 cm depth were compared using the criteria suggested by the AAPM Task Group # 53. Results: The PDD curves measured with gafchromic film and those measured in water with ion chamber agree with the ones calculated by RayStation within the uncertainty of the measurements which is within 3%. The passing rate values of the measured and calculated profiles for the 2 field sizes are within 94% for both at dmax and at 20 cm depth. Conclusion: Raystation dose calculation engine models inhomogeneity corrections. Differences between the calculated PDD curves and profiles and those measured with gafchromic film are within the uncertainty of the measurements and inside of the agreement tolerance suggested by TG53. Therefore, RayStation treatment planning has an acceptable algorithm to correct dose delivered by photon beams perturbed by lung tissue.« less

The use of tetrahedral mesh geometries in Monte Carlo simulation of applicator based brachytherapy dose distributions

NASA Astrophysics Data System (ADS)

Paiva Fonseca, Gabriel; Landry, Guillaume; White, Shane; D'Amours, Michel; Yoriyaz, Hélio; Beaulieu, Luc; Reniers, Brigitte; Verhaegen, Frank

2014-10-01

Accounting for brachytherapy applicator attenuation is part of the recommendations from the recent report of AAPM Task Group 186. To do so, model based dose calculation algorithms require accurate modelling of the applicator geometry. This can be non-trivial in the case of irregularly shaped applicators such as the Fletcher Williamson gynaecological applicator or balloon applicators with possibly irregular shapes employed in accelerated partial breast irradiation (APBI) performed using electronic brachytherapy sources (EBS). While many of these applicators can be modelled using constructive solid geometry (CSG), the latter may be difficult and time-consuming. Alternatively, these complex geometries can be modelled using tessellated geometries such as tetrahedral meshes (mesh geometries (MG)). Recent versions of Monte Carlo (MC) codes Geant4 and MCNP6 allow for the use of MG. The goal of this work was to model a series of applicators relevant to brachytherapy using MG. Applicators designed for 192Ir sources and 50 kV EBS were studied; a shielded vaginal applicator, a shielded Fletcher Williamson applicator and an APBI balloon applicator. All applicators were modelled in Geant4 and MCNP6 using MG and CSG for dose calculations. CSG derived dose distributions were considered as reference and used to validate MG models by comparing dose distribution ratios. In general agreement within 1% for the dose calculations was observed for all applicators between MG and CSG and between codes when considering volumes inside the 25% isodose surface. When compared to CSG, MG required longer computation times by a factor of at least 2 for MC simulations using the same code. MCNP6 calculation times were more than ten times shorter than Geant4 in some cases. In conclusion we presented methods allowing for high fidelity modelling with results equivalent to CSG. To the best of our knowledge MG offers the most accurate representation of an irregular APBI balloon applicator.

Effects of dual-task training on balance and executive functions in Parkinson's disease: A pilot study.

PubMed

Fernandes, Ângela; Rocha, Nuno; Santos, Rubim; Tavares, João Manuel R S

2015-01-01

The aim of this study was to analyze the efficacy of cognitive-motor dual-task training compared with single-task training on balance and executive functions in individuals with Parkinson's disease. Fifteen subjects, aged between 39 and 75 years old, were randomly assigned to the dual-task training group (n = 8) and single-task training group (n = 7). The training was run twice a week for 6 weeks. The single-task group received balance training and the dual-task group performed cognitive tasks simultaneously with the balance training. There were no significant differences between the two groups at baseline. After the intervention, the results for mediolateral sway with eyes closed were significantly better for the dual-task group and anteroposterior sway with eyes closed was significantly better for the single-task group. The results suggest superior outcomes for the dual-task training compared to the single-task training for static postural control, except in anteroposterior sway with eyes closed.

SU-E-T-524: Web-Based Radiation Oncology Incident Reporting and Learning System (ROIRLS)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kapoor, R; Palta, J; Hagan, M

Purpose: Describe a Web-based Radiation Oncology Incident Reporting and Learning system that has the potential to improve quality of care for radiation therapy patients. This system is an important facet of continuing effort by our community to maintain and improve safety of radiotherapy.Material and Methods: The VA National Radiation Oncology Program office has embarked on a program to electronically collect adverse events and near miss data of radiation treatment of over 25,000 veterans treated with radiotherapy annually. Software used for this program is deployed on the VAs intranet as a Website. All data entry forms (adverse event or near missmore » reports, work product reports) utilize standard causal, RT process step taxonomies and data dictionaries defined in AAPM and ASTRO reports on error reporting (AAPM Work Group Report on Prevention of Errors and ASTROs safety is no accident report). All reported incidents are investigated by the radiation oncology domain experts. This system encompasses the entire feedback loop of reporting an incident, analyzing it for salient details, and developing interventions to prevent it from happening again. The operational workflow is similar to that of the Aviation Safety Reporting System. This system is also synergistic with ROSIS and SAFRON. Results: The ROIRLS facilitates the collection of data that help in tracking adverse events and near misses and develop new interventions to prevent such incidents. The ROIRLS electronic infrastructure is fully integrated with each registered facility profile data thus minimizing key strokes and multiple entries by the event reporters. Conclusions: OIRLS is expected to improve the quality and safety of a broad spectrum of radiation therapy patients treated in the VA and fulfills our goal of Effecting Quality While Treating Safely The Radiation Oncology Incident Reporting and Learning System software used for this program has been developed, conceptualized and maintained by TSG Innovations Inc. and is deployed on the VA intranet as a Website. The Radiation Oncology Incident Reporting and Learning System software used for this program has been developed, conceptualized and maintained by TSG Innovations Inc. and is deployed on the VA intranet as a Website.« less

Management Information Task Group

DTIC Science & Technology

2002-12-18

Defense Business Practice Implementation Board Management Information Task Group Report...Std Z39-18 Defense Business Practice Implementation Board Management Information Task Group... Business Practice Implementation Board Management Information Task Group Report FY02-2 3

SU-E-J-170: Dosimetric Consequences of Uncorrected Rotational Setup Errors During Stereotactic Body Radiation Therapy (SBRT) Treatment of Pancreatic Cancers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Di Maso, L; Forbang, R Teboh; Zhang, Y

Purpose: To explore the dosimetric consequences of uncorrected rotational setup errors during SBRT for pancreatic cancer patients. Methods: This was a retrospective study utilizing data from ten (n=10) previously treated SBRT pancreas patients. For each original planning CT, we applied rotational transformations to derive additional CT images representative of possible rotational setup errors. This resulted in 6 different sets of rotational combinations, creating a total of 60 CT planning images. The patients’ clinical dosimetric plans were then applied to their corresponding rotated CT images. The 6 rotation sets encompassed a 3, 2 and 1-degree rotation in each rotational direction andmore » a 3-degree in just the pitch, a 3-degree in just the yaw and a 3-degree in just the roll. After the dosimetric plan was applied to the rotated CT images, the resulting plan was then evaluated and compared with the clinical plan for tumor coverage and normal tissue sparing. Results: PTV coverage, defined here by V33 throughout all of the patients’ clinical plans, ranged from 92–98%. After an n degree rotation in each rotational direction that range decreased to 68–87%, 85–92%, and 88– 94% for n=3, 2 and 1 respectively. Normal tissue sparing defined here by the proximal stomach V15 throughout all of the patients’ clinical plans ranged from 0–8.9 cc. After an n degree rotation in each rotational direction that range increased to 0–17 cc, 0–12 cc, and 0–10 cc for n=3, 2, and 1 respectively. Conclusion: For pancreatic SBRT, small rotational setup errors in the pitch, yaw and roll direction on average caused under dosage to PTV and over dosage to proximal normal tissue. The 1-degree rotation was on average the least detrimental to the normal tissue and the coverage of the PTV. The 3-degree yaw created on average the lowest increase in volume coverage to normal tissue. This research was sponsored by the AAPM Education Council through the AAPM Education and Research Fund for the AAPM Summer Undergraduate Fellowship Program.« less

The AAPM/RSNA physics tutorial for residents. Basic physics of MR imaging: an introduction.

PubMed

Hendrick, R E

1994-07-01

This article provides an introduction to the basic physical principles of magnetic resonance (MR) imaging. Essential basic concepts such as nuclear magnetism, tissue magnetization, precession, excitation, and tissue relaxation properties are presented. Hydrogen spin density and tissue relaxation times T1, T2, and T2* are explained. The basic elements of a planar MR pulse sequence are described: section selection during tissue excitation, phase encoding, and frequency encoding during signal measurement.

Annual Report Number 3, 1986.

DTIC Science & Technology

1986-01-01

REPORT 1986 as DISTPJUtIoN STATE’Tr A Agpprovod for public reI~laeC D is riL u ti o ’ Uni e L h i DIRECTORATE SJUN 109 OF D MANAGEMENT SCIENCES AFLC/XRS...21 2. Incorporate Aircraft Availability Into D041 . 22 3. Weapon System Phase In/Out And The Aircraft Availability Procurement Model (AAPM...Capabilities .. ......... 43 2. Evaluation Of CONUS Cargo Movement Requirements ........ ................. 4 3. Material Management Manpower Standars . 4.....44 V

WE-H-BRB-01: Overview of the ASTRO-NIH-AAPM 2015 Workshop On Exploring Opportunities for Radiation Oncology in the Era of Big Data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Benedict, S.

Big Data in Radiation Oncology: (1) Overview of the NIH 2015 Big Data Workshop, (2) Where do we stand in the applications of big data in radiation oncology?, and (3) Learning Health Systems for Radiation Oncology: Needs and Challenges for Future Success The overriding goal of this trio panel of presentations is to improve awareness of the wide ranging opportunities for big data impact on patient quality care and enhancing potential for research and collaboration opportunities with NIH and a host of new big data initiatives. This presentation will also summarize the Big Data workshop that was held at themore » NIH Campus on August 13–14, 2015 and sponsored by AAPM, ASTRO, and NIH. The workshop included discussion of current Big Data cancer registry initiatives, safety and incident reporting systems, and other strategies that will have the greatest impact on radiation oncology research, quality assurance, safety, and outcomes analysis. Learning Objectives: To discuss current and future sources of big data for use in radiation oncology research To optimize our current data collection by adopting new strategies from outside radiation oncology To determine what new knowledge big data can provide for clinical decision support for personalized medicine L. Xing, NIH/NCI Google Inc.« less

Comparison of IPSM 1990 photon dosimetry code of practice with IAEA TRS‐398 and AAPM TG‐51.

PubMed Central

Henríquez, Francisco Cutanda

2009-01-01

Several codes of practice for photon dosimetry are currently used around the world, supported by different organizations. A comparison of IPSM 1990 with both IAEA TRS‐398 and AAPM TG‐51 has been performed. All three protocols are based on the calibration of ionization chambers in terms of standards of absorbed dose to water, as it is the case with other modern codes of practice. This comparison has been carried out for photon beams of nominal energies: 4 MV, 6 MV, 8 MV, 10 MV and 18 MV. An NE 2571 graphite ionization chamber was used in this study, cross‐calibrated against an NE 2611A Secondary Standard, calibrated in the National Physical Laboratory (NPL). Absolute dose in reference conditions was obtained using each of these three protocols including: beam quality indices, beam quality conversion factors both theoretical and NPL experimental ones, correction factors for influence quantities and absolute dose measurements. Each protocol recommendations have been strictly followed. Uncertainties have been obtained according to the ISO Guide to the Expression of Uncertainty in Measurement. Absorbed dose obtained according to all three protocols agree within experimental uncertainty. The largest difference between absolute dose results for two protocols is obtained for the highest energy: 0.7% between IPSM 1990 and IAEA TRS‐398 using theoretical beam quality conversion factors. PACS number: 87.55.tm

Working Memory Training Improves Dual-Task Performance on Motor Tasks.

PubMed

Kimura, Takehide; Kaneko, Fuminari; Nagahata, Keita; Shibata, Eriko; Aoki, Nobuhiro

2017-01-01

The authors investigated whether working memory training improves motor-motor dual-task performance consisted of upper and lower limb tasks. The upper limb task was a simple reaction task and the lower limb task was an isometric knee extension task. 45 participants (age = 21.8 ± 1.6 years) were classified into a working memory training group (WM-TRG), dual-task training group, or control group. The training duration was 2 weeks (15 min, 4 times/week). Our results indicated that working memory capacity increased significantly only in the WM-TRG. Dual-task performance improved in the WM-TRG and dual-task training group. Our study provides the novel insight that working memory training improves dual-task performance without specific training on the target motor task.

A generic high-dose rate {sup 192}Ir brachytherapy source for evaluation of model-based dose calculations beyond the TG-43 formalism

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ballester, Facundo, E-mail: Facundo.Ballester@uv.es; Carlsson Tedgren, Åsa; Granero, Domingo

Purpose: In order to facilitate a smooth transition for brachytherapy dose calculations from the American Association of Physicists in Medicine (AAPM) Task Group No. 43 (TG-43) formalism to model-based dose calculation algorithms (MBDCAs), treatment planning systems (TPSs) using a MBDCA require a set of well-defined test case plans characterized by Monte Carlo (MC) methods. This also permits direct dose comparison to TG-43 reference data. Such test case plans should be made available for use in the software commissioning process performed by clinical end users. To this end, a hypothetical, generic high-dose rate (HDR) {sup 192}Ir source and a virtual watermore » phantom were designed, which can be imported into a TPS. Methods: A hypothetical, generic HDR {sup 192}Ir source was designed based on commercially available sources as well as a virtual, cubic water phantom that can be imported into any TPS in DICOM format. The dose distribution of the generic {sup 192}Ir source when placed at the center of the cubic phantom, and away from the center under altered scatter conditions, was evaluated using two commercial MBDCAs [Oncentra{sup ®} Brachy with advanced collapsed-cone engine (ACE) and BrachyVision ACUROS{sup TM}]. Dose comparisons were performed using state-of-the-art MC codes for radiation transport, including ALGEBRA, BrachyDose, GEANT4, MCNP5, MCNP6, and PENELOPE2008. The methodologies adhered to recommendations in the AAPM TG-229 report on high-energy brachytherapy source dosimetry. TG-43 dosimetry parameters, an along-away dose-rate table, and primary and scatter separated (PSS) data were obtained. The virtual water phantom of (201){sup 3} voxels (1 mm sides) was used to evaluate the calculated dose distributions. Two test case plans involving a single position of the generic HDR {sup 192}Ir source in this phantom were prepared: (i) source centered in the phantom and (ii) source displaced 7 cm laterally from the center. Datasets were independently produced by different investigators. MC results were then compared against dose calculated using TG-43 and MBDCA methods. Results: TG-43 and PSS datasets were generated for the generic source, the PSS data for use with the ACE algorithm. The dose-rate constant values obtained from seven MC simulations, performed independently using different codes, were in excellent agreement, yielding an average of 1.1109 ± 0.0004 cGy/(h U) (k = 1, Type A uncertainty). MC calculated dose-rate distributions for the two plans were also found to be in excellent agreement, with differences within type A uncertainties. Differences between commercial MBDCA and MC results were test, position, and calculation parameter dependent. On average, however, these differences were within 1% for ACUROS and 2% for ACE at clinically relevant distances. Conclusions: A hypothetical, generic HDR {sup 192}Ir source was designed and implemented in two commercially available TPSs employing different MBDCAs. Reference dose distributions for this source were benchmarked and used for the evaluation of MBDCA calculations employing a virtual, cubic water phantom in the form of a CT DICOM image series. The implementation of a generic source of identical design in all TPSs using MBDCAs is an important step toward supporting univocal commissioning procedures and direct comparisons between TPSs.« less

Assessment of display performance for medical imaging systems: Executive summary of AAPM TG18 report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Samei, Ehsan; Badano, Aldo; Chakraborty, Dev

Digital imaging provides an effective means to electronically acquire, archive, distribute, and view medical images. Medical imaging display stations are an integral part of these operations. Therefore, it is vitally important to assure that electronic display devices do not compromise image quality and ultimately patient care. The AAPM Task Group 18 (TG18) recently published guidelines and acceptance criteria for acceptance testing and quality control of medical display devices. This paper is an executive summary of the TG18 report. TG18 guidelines include visual, quantitative, and advanced testing methodologies for primary and secondary class display devices. The characteristics, tested in conjunction withmore » specially designed test patterns (i.e., TG18 patterns), include reflection, geometric distortion, luminance, the spatial and angular dependencies of luminance, resolution, noise, glare, chromaticity, and display artifacts. Geometric distortions are evaluated by linear measurements of the TG18-QC test pattern, which should render distortion coefficients less than 2%/5% for primary/secondary displays, respectively. Reflection measurements include specular and diffuse reflection coefficients from which the maximum allowable ambient lighting is determined such that contrast degradation due to display reflection remains below a 20% limit and the level of ambient luminance (L{sub amb}) does not unduly compromise luminance ratio (LR) and contrast at low luminance levels. Luminance evaluation relies on visual assessment of low contrast features in the TG18-CT and TG18-MP test patterns, or quantitative measurements at 18 distinct luminance levels of the TG18-LN test patterns. The major acceptable criteria for primary/secondary displays are maximum luminance of greater than 170/100 cd/m{sup 2}, LR of greater than 250/100, and contrast conformance to that of the grayscale standard display function (GSDF) of better than 10%/20%, respectively. The angular response is tested to ascertain the viewing cone within which contrast conformance to the GSDF is better than 30%/60% and LR is greater than 175/70 for primary/secondary displays, or alternatively, within which the on-axis contrast thresholds of the TG18-CT test pattern remain discernible. The evaluation of luminance spatial uniformity at two distinct luminance levels across the display faceplate using TG18-UNL test patterns should yield nonuniformity coefficients smaller than 30%. The resolution evaluation includes the visual scoring of the CX test target in the TG18-QC or TG18-CX test patterns, which should yield scores greater than 4/6 for primary/secondary displays. Noise evaluation includes visual evaluation of the contrast threshold in the TG18-AFC test pattern, which should yield a minimum of 3/2 targets visible for primary/secondary displays. The guidelines also include methodologies for more quantitative resolution and noise measurements based on MTF and NPS analyses. The display glare test, based on the visibility of the low-contrast targets of the TG18-GV test pattern or the measurement of the glare ratio (GR), is expected to yield scores greater than 3/1 and GRs greater than 400/150 for primary/secondary displays. Chromaticity, measured across a display faceplate or between two display devices, is expected to render a u{sup '},v{sup '} color separation of less than 0.01 for primary displays. The report offers further descriptions of prior standardization efforts, current display technologies, testing prerequisites, streamlined procedures and timelines, and TG18 test patterns.« less

Prior cognitive activity implicitly modulates subsequent emotional responses to subliminally presented emotional stimuli.

PubMed

Iida, Saea; Nakao, Takashi; Ohira, Hideki

2012-06-01

It has been reported that engagement in several kinds of cognitive activity can successfully inhibit unpleasant emotions. In this study, we tried to replicate the previous finding that cognitive activity can modulate subsequent psychological and physiological emotional processes and to investigate whether prior cognitive activity can attenuate implicit emotional processes triggered by subliminal emotional stimuli. Sixty students were randomly divided into three groups (cognitive task group, noncognitive task group, control group). The cognitive task group was asked to engage in an n-back task, while the control group was asked to stay calm. The noncognitive task group was asked to do a handgrip-squeezing task. All participants then engaged in a version of a subliminal affective priming task where they were unconsciously exposed to affectively negative pictures. The cognitive task group showed lower negative experiences after the subliminal affective priming task and a substantial reduction in their heart rate responses, as compared with the other groups. These results provide evidence that engagement in cognitive activity can attenuate emotional processes in an automatic and unconscious manner.

Conflict's consequences: effects of social motives on postnegotiation creative and convergent group functioning and performance.

PubMed

Beersma, Bianca; De Dreu, Carsten K W

2005-09-01

Two studies tested the effects of social motives during negotiation on postnegotiation group performance. In both experiments, a prosocial or a proself motivation was induced, and participants negotiated in 3-person groups about a joint market. In Experiment 1, groups subsequently performed an advertisement task. Consistent with the authors' predictions, results showed that proself groups performed worse on the convergent aspects of this task but better on the divergent aspects than prosocial groups. In Experiment 2, the authors manipulated social motive and negotiation (negotiation vs. no negotiation), and groups performed a creativity task (requiring divergent performance) or a planning task (requiring convergent performance). Proself groups showed greater dedication, functioned more effectively, and performed better than prosocial groups on the creativity task, whereas prosocial groups showed greater dedication, functioned more effectively, and performed better than proself groups on the planning task, and these effects only occurred when the task was preceded by group negotiation.

A Demands-Resources Model of Work Pressure in IT Student Task Groups

ERIC Educational Resources Information Center

Wilson, E. Vance; Sheetz, Steven D.

2010-01-01

This paper presents an initial test of the group task demands-resources (GTD-R) model of group task performance among IT students. We theorize that demands and resources in group work influence formation of perceived group work pressure (GWP) and that heightened levels of GWP inhibit group task performance. A prior study identified 11 factors…

Dosimetric characterization of the M−15 high‐dose‐rate Iridium−192 brachytherapy source using the AAPM and ESTRO formalism

PubMed Central

Thanh, Minh‐Tri Ho; Munro, John J.

2015-01-01

The Source Production & Equipment Co. (SPEC) model M−15 is a new Iridium−192 brachytherapy source model intended for use as a temporary high‐dose‐rate (HDR) brachytherapy source for the Nucletron microSelectron Classic afterloading system. The purpose of this study is to characterize this HDR source for clinical application by obtaining a complete set of Monte Carlo calculated dosimetric parameters for the M‐15, as recommended by AAPM and ESTRO, for isotopes with average energies greater than 50 keV. This was accomplished by using the MCNP6 Monte Carlo code to simulate the resulting source dosimetry at various points within a pseudoinfinite water phantom. These dosimetric values next were converted into the AAPM and ESTRO dosimetry parameters and the respective statistical uncertainty in each parameter also calculated and presented. The M−15 source was modeled in an MCNP6 Monte Carlo environment using the physical source specifications provided by the manufacturer. Iridium−192 photons were uniformly generated inside the iridium core of the model M−15 with photon and secondary electron transport replicated using photoatomic cross‐sectional tables supplied with MCNP6. Simulations were performed for both water and air/vacuum computer models with a total of 4×109 sources photon history for each simulation and the in‐air photon spectrum filtered to remove low‐energy photons below δ=10%keV. Dosimetric data, including D(r,θ),gL(r),F(r,θ),Φan(r), and φ¯an, and their statistical uncertainty were calculated from the output of an MCNP model consisting of an M−15 source placed at the center of a spherical water phantom of 100 cm diameter. The air kerma strength in free space, SK, and dose rate constant, Λ, also was computed from a MCNP model with M−15 Iridium−192 source, was centered at the origin of an evacuated phantom in which a critical volume containing air at STP was added 100 cm from the source center. The reference dose rate, D˙(r0,θ0)≡D˙(1cm,π/2), is found to be 4.038±0.064 cGy mCi−1 h−1. The air kerma strength, SK, is reported to be 3.632±0.086 cGy cm2 mCi−1 g−1, and the dose rate constant, Λ, is calculated to be 1.112±0.029 cGy h−1 U−1. The normalized dose rate, radial dose function, and anisotropy function with their uncertainties were computed and are represented in both tabular and graphical format in the report. A dosimetric study was performed of the new M−15 Iridium−192 HDR brachytherapy source using the MCNP6 radiation transport code. Dosimetric parameters, including the dose‐rate constant, radial dose function, and anisotropy function, were calculated in accordance with the updated AAPM and ESTRO dosimetric parameters for brachytherapy sources of average energy greater than 50 keV. These data therefore may be applied toward the development of a treatment planning program and for clinical use of the source. PACS numbers: 87.56.bg, 87.53.Jw PMID:26103489

Does the medium matter? The interaction of task type and technology on group performance and member reactions.

PubMed

Straus, S G; McGrath, J E

1994-02-01

The authors investigated the hypothesis that as group tasks pose greater requirements for member interdependence, communication media that transmit more social context cues will foster group performance and satisfaction. Seventy-two 3-person groups of undergraduate students worked in either computer-mediated or face-to-face meetings on 3 tasks with increasing levels of interdependence: an idea-generation task, an intellective task, and a judgment task. Results showed few differences between computer-mediated and face-to-face groups in the quality of the work completed but large differences in productivity favoring face-to-face groups. Analysis of productivity and of members' reactions supported the predicted interaction of tasks and media, with greater discrepancies between media conditions for tasks requiring higher levels of coordination. Results are discussed in terms of the implications of using computer-mediated communications systems for group work.

Guidelines by the AAPM and GEC-ESTRO on the use of innovative brachytherapy devices and applications: Report of Task Group 167

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nath, Ravinder; Rivard, Mark J., E-mail: mark.j.rivard@gmail.com; DeWerd, Larry A.

Although a multicenter, Phase III, prospective, randomized trial is the gold standard for evidence-based medicine, it is rarely used in the evaluation of innovative devices because of many practical and ethical reasons. It is usually sufficient to compare the dose distributions and dose rates for determining the equivalence of the innovative treatment modality to an existing one. Thus, quantitative evaluation of the dosimetric characteristics of innovative radiotherapy devices or applications is a critical part in which physicists should be actively involved. The physicist’s role, along with physician colleagues, in this process is highlighted for innovative brachytherapy devices and applications andmore » includes evaluation of (1) dosimetric considerations for clinical implementation (including calibrations, dose calculations, and radiobiological aspects) to comply with existing societal dosimetric prerequisites for sources in routine clinical use, (2) risks and benefits from a regulatory and safety perspective, and (3) resource assessment and preparedness. Further, it is suggested that any developed calibration methods be traceable to a primary standards dosimetry laboratory (PSDL) such as the National Institute of Standards and Technology in the U.S. or to other PSDLs located elsewhere such as in Europe. Clinical users should follow standards as approved by their country’s regulatory agencies that approved such a brachytherapy device. Integration of this system into the medical source calibration infrastructure of secondary standard dosimetry laboratories such as the Accredited Dosimetry Calibration Laboratories in the U.S. is encouraged before a source is introduced into widespread routine clinical use. The American Association of Physicists in Medicine and the Groupe Européen de Curiethérapie-European Society for Radiotherapy and Oncology (GEC-ESTRO) have developed guidelines for the safe and consistent application of brachytherapy using innovative devices and applications. The current report covers regulatory approvals, calibration, dose calculations, radiobiological issues, and overall safety concerns that should be addressed during the commissioning stage preceding clinical use. These guidelines are based on review of requirements of the U.S. Nuclear Regulatory Commission, U.S. Department of Transportation, International Electrotechnical Commission Medical Electrical Equipment Standard 60601, U.S. Food and Drug Administration, European Commission for CE Marking (Conformité Européenne), and institutional review boards and radiation safety committees.« less

Developmental changes in using verbal self-cueing in task-switching situations: the impact of task practice and task-sequencing demands.

PubMed

Kray, Jutta; Gaspard, Hanna; Karbach, Julia; Blaye, Agnès

2013-01-01

In this study we examined whether developmental changes in using verbal self-cueing for task-goal maintenance are dependent on the amount of task practice and task-sequencing demands. To measure task-goal maintenance we applied a switching paradigm in which children either performed only task A or B in single-task blocks or switched between them on every second trial in mixed-task blocks. Task-goal maintenance was determined by comparing the performance between both blocks (mixing costs). The influence of verbal self-cueing was measured by instructing children to either name the next task aloud or not to verbalize during task preparation. Task-sequencing demands were varied between groups whereas one group received spatial task cues to support keeping track of the task sequence, while the other group did not. We also varied by the amount of prior practice in task switching while one group of participants practiced task switching first, before performing the task naming in addition, and the other group did it vice versa. Results of our study investigating younger (8-10 years) and older children (11-13 years) revealed no age differences in beneficial effects of verbal self-cueing. In line with previous findings, children showed reduced mixing costs under task-naming instructions and under conditions of low task-sequence demands (with the presence of spatial task cues). Our results also indicated that these benefits were only obtained for those groups of children that first received practice in task switching alone with no additional verbalization instruction. These findings suggest that internal task-cueing strategies can be efficiently used in children but only if they received prior practice in the underlying task so that demands on keeping and coordinating various instructions are reduced. Moreover, children benefitted from spatial task cues for better task-goal maintenance only if no verbal task-cueing strategy was introduced first.

Watch and Learn: Seeing Is Better than Doing when Acquiring Consecutive Motor Tasks

PubMed Central

Larssen, Beverley C.; Ong, Nicole T.; Hodges, Nicola J.

2012-01-01

During motor adaptation learning, consecutive physical practice of two different tasks compromises the retention of the first. However, there is evidence that observational practice, while still effectively aiding acquisition, will not lead to interference and hence prove to be a better practice method. Observers and Actors practised in a clockwise (Task A) followed by a counterclockwise (Task B) visually rotated environment, and retention was immediately assessed. An Observe-all and Act-all group were compared to two groups who both physically practised Task A, but then only observed (ObsB) or did not see or practice Task B (NoB). The two observer groups and the NoB control group better retained Task A than Actors, although importantly only the observer groups learnt Task B. RT data and explicit awareness of the rotation suggested that the observers had acquired their respective tasks in a more strategic manner than Actor and Control groups. We conclude that observational practice benefits learning of multiple tasks more than physical practice due to the lack of updating of implicit, internal models for aiming in the former. PMID:22723909

Effect of the cognitive-motor dual-task using auditory cue on balance of surviviors with chronic stroke: a pilot study.

PubMed

Choi, Wonjae; Lee, GyuChang; Lee, Seungwon

2015-08-01

To investigate the effect of a cognitive-motor dual-task using auditory cues on the balance of patients with chronic stroke. Randomized controlled trial. Inpatient rehabilitation center. Thirty-seven individuals with chronic stroke. The participants were randomly allocated to the dual-task group (n=19) and the single-task group (n=18). The dual-task group performed a cognitive-motor dual-task in which they carried a circular ring from side to side according to a random auditory cue during treadmill walking. The single-task group walked on a treadmill only. All subjects completed 15 min per session, three times per week, for four weeks with conventional rehabilitation five times per week over the four weeks. Before and after intervention, both static and dynamic balance were measured with a force platform and using the Timed Up and Go (TUG) test. The dual-task group showed significant improvement in all variables compared to the single-task group, except for anteroposterior (AP) sway velocity with eyes open and TUG at follow-up: mediolateral (ML) sway velocity with eye open (dual-task group vs. single-task group: 2.11 mm/s vs. 0.38 mm/s), ML sway velocity with eye close (2.91 mm/s vs. 1.35 mm/s), AP sway velocity with eye close (4.84 mm/s vs. 3.12 mm/s). After intervention, all variables showed significant improvement in the dual-task group compared to baseline. The study results suggest that the performance of a cognitive-motor dual-task using auditory cues may influence balance improvements in chronic stroke patients. © The Author(s) 2014.

Effects of dual-task balance training on postural performance in patients with Multiple Sclerosis: a double-blind, randomized controlled pilot trial.

PubMed

Monjezi, Saeideh; Negahban, Hossein; Tajali, Shirin; Yadollahpour, Nava; Majdinasab, Nastaran

2017-02-01

To investigate the effects of dual-task balance training on postural performance in patients with multiple sclerosis as compared with single-task balance training. Double-blind, pretest-posttest, randomized controlled pilot trial. Local Multiple Sclerosis Society. A total of 47 patients were randomly assigned to two equal groups labeled as single-task training and dual-task training groups. All patients received supervised balance training sessions, 3 times per week for 4 weeks. The patients in the single-task group performed balance activities, alone. However, patients in dual-task group practiced balance activities while simultaneously performing cognitive tasks. The 10-Meter Walk Test and Timed Up-and-Go under single-task and dual-task conditions, in addition to Activities-specific Balance Confidence, Berg Balance Scale, and Functional Gait Assessment were assessed pre-, and post intervention and also 6-weeks after the end of intervention. Only 38 patients completed the treatment plan. There was no difference in the amount of improvement seen between the two study groups. In both groups there was a significant effect of time for dual-10 Meter Walk Test (F 1, 36 =11.33, p=0.002) and dual-Timed Up-and-Go (F 1, 36 =14.27, p=0.001) but not for their single-tasks. Moreover, there was a significant effect of time for Activities-specific Balance Confidence, Berg Balance Scale, and Functional Gait Assessment ( P<0.01). This pilot study did not show more benefits from undertaking dual-task training than single-task training. A power analysis showed 71 patients per group would be needed to determine whether there was a clinically relevant difference for dual-task gait speed between the groups.

Common region wins the competition between extrinsic grouping cues: Evidence from a task without explicit attention to grouping.

PubMed

Montoro, Pedro R; Villalba-García, Cristina; Luna, Dolores; Hinojosa, José A

2017-12-01

The competition between perceptual grouping factors is a relatively ignored topic, especially in the case of extrinsic grouping cues (e.g., common region or connectedness). Recent studies have examined the integration of extrinsic cues using tasks that induce selective attention to groups based on different grouping cues. However, this procedure could generate alternative strategies for task performance, which are non-related to the perceptual grouping operations. In the current work, we used an indirect task, i.e. repetition discrimination task, without explicit attention to grouping cues to further examine the rules that govern dominance between competing extrinsic grouping factors. This procedure allowed us to obtain an unbiased measure of the competition between common region and connectedness cues acting within the same display. The results corroborate previous data showing that grouping by common region dominated the perceived organization of the display, even though the phenomenological strength of the grouping cues was equated for each participant by means of a preliminary scaling task. Our results highlight the relevance of using indirect tasks as an essential tool for the systematic study of the integration of extrinsic grouping cues.

Explaining Dynamic Interactions in Wiki-Based Collaborative Writing

ERIC Educational Resources Information Center

Li, Mimi; Zhu, Wei

2017-01-01

This article reports a case study that examined dynamic patterns of interaction that two small groups (Group A and Group B) of ESL students exemplified when they performed two writing tasks: a research proposal (Task 1) and an annotated bibliography (Task 2) in a wiki site. Group A demonstrated a collective pattern in Task 1, but switched to an…

The role of motivation in distracting attention away from pain: an experimental study.

PubMed

Verhoeven, Katrien; Crombez, Geert; Eccleston, Christopher; Van Ryckeghem, Dimitri M L; Morley, Stephen; Van Damme, Stefaan

2010-05-01

Research on the effectiveness of distraction as a method of pain control is inconclusive. One mechanism pertains to the motivational relevance of distraction tasks. In this study the motivation to engage in a distraction task during pain was experimentally manipulated. Undergraduate students (N=73) participated in a cold pressor test (CPT) and were randomly assigned to three groups: a distraction-only group performed a tone-detection task during the CPT, a motivated-distraction group performed the same task and received a monetary reward for good task performance, and a control group did not perform the tone-detection task. Results indicated that engagement in the distraction task was better in the motivated-distraction group in comparison with the distraction-only group. Participants in both distraction groups experienced less pain compared to the control group. There were no overall differences in pain intensity between the two distraction groups. The effect of distraction was influenced by the level of catastrophic thinking about pain. For low catastrophizers, both distraction groups reported less pain as compared to the non-distracted control group. This was not the case for high catastrophizers. For high catastrophizers it mattered whether the distraction task was motivationally relevant: high catastrophizers reported less intense pain in the motivated-distraction group, as compared to the non-distracted control group. We conclude that increasing the motivational relevance of the distraction task may increase the effects of distraction, especially for those who catastrophize about pain. Copyright 2010 International Association for the Study of Pain. Published by Elsevier B.V. All rights reserved.

MO-DE-206-00: Joint AAPM-WMIS Symposium: Metabolic Imaging of Cancer

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

In this symposium jointly sponsored by the World Molecular Imaging Society (WMIS) and the AAPM, luminary speakers on imaging metabolism will discuss three impactful topics. The first presentation on Cellular Metabolism of FDG will be given by Guillem Pratx (Stanford). This presentation will detail new work on looking at how the most common molecular imaging agent, fluoro-deoxy-glucose is metabolized at a cellular level. This will be followed by a talk on an improved approach to whole-body PET imaging by Simon Cherry (UC Davis). Simon’s work on a new whole-body PET imaging system promises to have dramatic improvement in our abilitymore » to detect and characterize cancer using PET. Finally, Jim Bankson (MD Anderson) will discuss extremely sophisticated approaches to quantifying hyperpolarized-13-C pyruvate metabolism using MR imaging. This technology promises to compliment the exquisite sensitivity of PET with an ability to measure not just uptake, but tumor metabolism. Learning Objectives: Understand the metabolism of FDG at a cellular level. Appreciate the engineering related to a novel new high-sensitivity whole-body PET imaging system. Understand the process of hyperpolarization, how pyruvate relates to metabolism and how advanced modeling can be used to better quantify this data. G. Pratx, Funding: 5R01CA186275, 1R21CA193001, and Damon Runyon Cancer Foundation. S. Cherry, National Institutes of Health; University of California, Davis; Siemens Medical SolutionsJ. Bankson, GE Healthcare; NCI P30-CA016672; CPRIT PR140021-P5.« less

MO-FG-BRC-00: Joint AAPM-ESTRO Symposium: Advances in Experimental Medical Physics

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

Experimental research in medical physics has expanded the limits of our knowledge and provided novel imaging and therapy technologies for patients around the world. However, experimental efforts are challenging due to constraints in funding, space, time and other forms of institutional support. In this joint ESTRO-AAPM symposium, four exciting experimental projects from four different countries are highlighted. Each project is focused on a different aspect of radiation therapy. From the USA, we will hear about a new linear accelerator concept for more compact and efficient therapy devices. From Canada, we will learn about novel linear accelerator target design and themore » implications for imaging and therapy. From France, we will discover a mature translational effort to incorporate theranostic nanoparticles in MR-guided radiation therapy. From Germany, we will find out about a novel in-treatment imaging modality for particle therapy. These examples of high impact, experimental medical physics research are representative of the diversity of such efforts that are on-going around the globe. J. Robar, Research is supported through collaboration with Varian Medical Systems and Brainlab AGD. Westerly, This work is supported by the Department of Radiation Oncology at the University of Colorado School of Medicine. COI: NONEK. Parodi, Part of the presented work is supported by the DFG (German Research Foundation) Cluster of Excellence MAP (Munich-Centre for Advanced Photonics) and has been carried out in collaboration with IBA.« less

MO-A-213-00: Economics Update

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

2015-06-15

The purpose of this session is to introduce attendees to the healthcare reimbursement system and how it applies to the clinical work of a Medical Physicist. This will include general information about the different categories of payers and payees, how work is described by CPT© codes, and how various payers set values for this work in different clinical settings. 2015 is a year of significant changes to the payment system. Many CPT© codes have been deleted and replaced with new CPT© codes. These codes define some of the most common work performed in our clinics including treatment planning and delivery.more » This presentation will describe what work is encompassed in these codes and will give attendees an overview of the changes for 2015 as they apply to radiation oncology. Finally, some insight into what can be expected during 2016 will be presented. This includes what information is typically released by the Centers for Medicaid & Medicare Services (CMS) during the year and how we as an organization respond. This will include ways members can interact with the AAPM professional economics committee and other resources members may find helpful. Learning Objectives: Basics of how Medicare is structured and how reimbursement rates are set. Basic understanding of proposed changes to the 2016 Medicare rules. What resources are available from the AAPM and how to interact with the professional economics committee. Ownership in pxAlpha, LLC, a medical device start up company.« less

MO-A-213-01: 2015 Economics Update Part 1

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dirksen, B.

2015-06-15

The purpose of this session is to introduce attendees to the healthcare reimbursement system and how it applies to the clinical work of a Medical Physicist. This will include general information about the different categories of payers and payees, how work is described by CPT© codes, and how various payers set values for this work in different clinical settings. 2015 is a year of significant changes to the payment system. Many CPT© codes have been deleted and replaced with new CPT© codes. These codes define some of the most common work performed in our clinics including treatment planning and delivery.more » This presentation will describe what work is encompassed in these codes and will give attendees an overview of the changes for 2015 as they apply to radiation oncology. Finally, some insight into what can be expected during 2016 will be presented. This includes what information is typically released by the Centers for Medicaid & Medicare Services (CMS) during the year and how we as an organization respond. This will include ways members can interact with the AAPM professional economics committee and other resources members may find helpful. Learning Objectives: Basics of how Medicare is structured and how reimbursement rates are set. Basic understanding of proposed changes to the 2016 Medicare rules. What resources are available from the AAPM and how to interact with the professional economics committee. Ownership in pxAlpha, LLC, a medical device start up company.« less

MO-A-213-02: 2015 Economics Update Part 2

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fontenot, J.

2015-06-15

The purpose of this session is to introduce attendees to the healthcare reimbursement system and how it applies to the clinical work of a Medical Physicist. This will include general information about the different categories of payers and payees, how work is described by CPT© codes, and how various payers set values for this work in different clinical settings. 2015 is a year of significant changes to the payment system. Many CPT© codes have been deleted and replaced with new CPT© codes. These codes define some of the most common work performed in our clinics including treatment planning and delivery.more » This presentation will describe what work is encompassed in these codes and will give attendees an overview of the changes for 2015 as they apply to radiation oncology. Finally, some insight into what can be expected during 2016 will be presented. This includes what information is typically released by the Centers for Medicaid & Medicare Services (CMS) during the year and how we as an organization respond. This will include ways members can interact with the AAPM professional economics committee and other resources members may find helpful. Learning Objectives: Basics of how Medicare is structured and how reimbursement rates are set. Basic understanding of proposed changes to the 2016 Medicare rules. What resources are available from the AAPM and how to interact with the professional economics committee. Ownership in pxAlpha, LLC, a medical device start up company.« less

Monte Carlo simulations in CT for the study of the surface air kerma and energy imparted to phantoms of varying size and position

NASA Astrophysics Data System (ADS)

Avilés Lucas, P.; Dance, D. R.; Castellano, I. A.; Vañó, E.

2004-04-01

A Monte Carlo computational model of CT has been developed and used to investigate the effect of various physical factors on the surface air kerma length product, the peak surface air kerma, the air kerma length product within a phantom and the energy imparted. The factors investigated were the bow-tie filter and the size, shape and position of a phantom which simulates the patient. The calculations show that the surface air kerma length product and the maximum surface air kerma are mainly dependent on phantom position and decrease along the vertical axis of the CT plane as the phantom surface moves away from the isocentre along this axis. As a result, measurements using standard body dosimetry phantoms may underestimate the skin dose for real patients. This result is specially important for CT fluoroscopic procedures: for an adult patient the peak skin dose can be 37% higher than that estimated with a standard measurement on the body AAPM (American Association of Physicists in Medicine) phantom. The results also show that the energy imparted to a phantom is mainly influenced by phantom size and is nearly independent of phantom position (within 3%) and shape (up to 5% variation). However, variations of up to 30% were found for the air kerma to regions within the AAPM body phantom when it is moved vertically. This highlights the importance of calculating doses to organs taking into account their size and position within the gantry.

Reasoning in people with obsessive-compulsive disorder.

PubMed

Simpson, Jane; Cove, Jennifer; Fineberg, Naomi; Msetfi, Rachel M; J Ball, Linden

2007-11-01

The aim of this study was to investigate the inductive and deductive reasoning abilities of people with obsessive-compulsive disorder (OCD). Following previous research, it was predicted that people with OCD would show different abilities on inductive reasoning tasks but similar abilities to controls on deductive reasoning tasks. A two-group comparison was used with both groups matched on a range of demographic variables. Where appropriate, unmatched variables were entered into the analyses as covariates. Twenty-three people with OCD and 25 control participants were assessed on two tasks: an inductive reasoning task (the 20-questions task) and a deductive reasoning task (a syllogistic reasoning task with a content-neutral and content-emotional manipulation). While no group differences emerged on several of the parameters of the inductive reasoning task, the OCD group did differ on one, and arguably the most important, parameter by asking fewer correct direct-hypothesis questions. The syllogistic reasoning task results were analysed using both correct response and conclusion acceptance data. While no main effects of group were evident, significant interactions indicated important differences in the way the OCD group reasoned with content neutral and emotional syllogisms. It was argued that the OCD group's patterns of response on both tasks were characterized by the need for more information, states of uncertainty, and doubt and postponement of a final decision.

Cognitive Performance and Heart Rate Variability: The Influence of Fitness Level

PubMed Central

Luque-Casado, Antonio; Zabala, Mikel; Morales, Esther; Mateo-March, Manuel; Sanabria, Daniel

2013-01-01

In the present study, we investigated the relation between cognitive performance and heart rate variability as a function of fitness level. We measured the effect of three cognitive tasks (the psychomotor vigilance task, a temporal orienting task, and a duration discrimination task) on the heart rate variability of two groups of participants: a high-fit group and a low-fit group. Two major novel findings emerged from this study. First, the lowest values of heart rate variability were found during performance of the duration discrimination task, compared to the other two tasks. Second, the results showed a decrement in heart rate variability as a function of the time on task, although only in the low-fit group. Moreover, the high-fit group showed overall faster reaction times than the low-fit group in the psychomotor vigilance task, while there were not significant differences in performance between the two groups of participants in the other two cognitive tasks. In sum, our results highlighted the influence of cognitive processing on heart rate variability. Importantly, both behavioral and physiological results suggested that the main benefit obtained as a result of fitness level appeared to be associated with processes involving sustained attention. PMID:23437276

Association between educational status and dual-task performance in young adults.

PubMed

Voos, Mariana Callil; Pimentel Piemonte, Maria Elisa; Castelli, Lilian Zanchetta; Andrade Machado, Mariane Silva; Dos Santos Teixeira, Patrícia Pereira; Caromano, Fátima Aparecida; Ribeiro Do Valle, Luiz Eduardo

2015-04-01

The influence of educational status on perceptual-motor performance has not been investigated. The single- and dual-task performances of 15 Low educated adults (9 men, 6 women; M age=24.1 yr.; 6-9 yr. of education) and 15 Higher educated adults (8 men, 7 women; M age=24.7 yr.; 10-13 yr. of education) were compared. The perceptual task consisted of verbally classifying two figures (equal or different). The motor task consisted of alternating steps from the floor to a stool. Tasks were assessed individually and simultaneously. Two analyses of variance (2 groups×4 blocks) compared the errors and steps. The Low education group committed more errors and had less improvement on the perceptual task than the High education group. During and after the perceptual-motor task performance, errors increased only in the Low education group. Education correlated to perceptual and motor performance. The Low education group showed more errors and less step alternations on the perceptual-motor task compared to the High education group. This difference on the number of errors was also observed after the dual-task, when the perceptual task was performed alone.

Consecutive learning of opposing unimanual motor tasks using the right arm followed by the left arm causes intermanual interference

PubMed Central

Thürer, Benjamin; Stein, Thorsten

2017-01-01

Intermanual transfer (motor memory generalization across arms) and motor memory interference (impairment of retest performance in consecutive motor learning) are well-investigated motor learning phenomena. However, the interplay of these phenomena remains elusive, i.e., whether intermanual interference occurs when two unimanual tasks are consecutively learned using different arms. Here, we examine intermanual interference when subjects consecutively adapt their right and left arm movements to novel dynamics. We considered two force field tasks A and B which were of the same structure but mirrored orientation (B = -A). The first test group (ABA-group) consecutively learned task A using their right arm and task B using their left arm before being retested for task A with their right arm. Another test group (AAA-group) learned only task A in the same right-left-right arm schedule. Control subjects learned task A using their right arm without intermediate left arm learning. All groups were able to adapt their right arm movements to force field A and both test groups showed significant intermanual transfer of this initial learning to the contralateral left arm of 21.9% (ABA-group) and 27.6% (AAA-group). Consecutively, both test groups adapted their left arm movements to force field B (ABA-group) or force field A (AAA-group). For the ABA-group, left arm learning caused significant intermanual interference of the initially learned right arm task (68.3% performance decrease). The performance decrease of the AAA-group (10.2%) did not differ from controls (15.5%). These findings suggest that motor control and learning of right and left arm movements involve partly similar neural networks or underlie a vital interhemispheric connectivity. Moreover, our results suggest a preferred internal task representation in extrinsic Cartesian-based coordinates rather than in intrinsic joint-based coordinates because interference was absent when learning was performed in extrinsically equivalent fashion (AAA-group) but interference occurred when learning was performed in intrinsically equivalent fashion (ABA-group). PMID:28459833

Consecutive learning of opposing unimanual motor tasks using the right arm followed by the left arm causes intermanual interference.

PubMed

Stockinger, Christian; Thürer, Benjamin; Stein, Thorsten

2017-01-01

Intermanual transfer (motor memory generalization across arms) and motor memory interference (impairment of retest performance in consecutive motor learning) are well-investigated motor learning phenomena. However, the interplay of these phenomena remains elusive, i.e., whether intermanual interference occurs when two unimanual tasks are consecutively learned using different arms. Here, we examine intermanual interference when subjects consecutively adapt their right and left arm movements to novel dynamics. We considered two force field tasks A and B which were of the same structure but mirrored orientation (B = -A). The first test group (ABA-group) consecutively learned task A using their right arm and task B using their left arm before being retested for task A with their right arm. Another test group (AAA-group) learned only task A in the same right-left-right arm schedule. Control subjects learned task A using their right arm without intermediate left arm learning. All groups were able to adapt their right arm movements to force field A and both test groups showed significant intermanual transfer of this initial learning to the contralateral left arm of 21.9% (ABA-group) and 27.6% (AAA-group). Consecutively, both test groups adapted their left arm movements to force field B (ABA-group) or force field A (AAA-group). For the ABA-group, left arm learning caused significant intermanual interference of the initially learned right arm task (68.3% performance decrease). The performance decrease of the AAA-group (10.2%) did not differ from controls (15.5%). These findings suggest that motor control and learning of right and left arm movements involve partly similar neural networks or underlie a vital interhemispheric connectivity. Moreover, our results suggest a preferred internal task representation in extrinsic Cartesian-based coordinates rather than in intrinsic joint-based coordinates because interference was absent when learning was performed in extrinsically equivalent fashion (AAA-group) but interference occurred when learning was performed in intrinsically equivalent fashion (ABA-group).

Mental Imagery and Idiom Understanding in Adults: Examining Dual Coding Theory

ERIC Educational Resources Information Center

Hung, Pei-Fang

2010-01-01

This study examined idiom understanding in 120 neurologically healthy adults, ages 20-29 (20s Group), 40-49 (40s Group), 60-69 (60s Group), and 80-89 (80s Group) years old. Each participant was administered a familiarity task, definition explanation task, mental imagery task, and forced-choice comprehension task. Twenty idioms, 10 transparent and…

Ethics and professionalism in medical physics: a survey of AAPM members.

PubMed

Ozturk, Naim; Armato, Samuel G; Giger, Maryellen L; Serago, Christopher F; Ross, Lainie F

2013-04-01

To assess current education, practices, attitudes, and perceptions pertaining to ethics and professionalism in medical physics. A link to a web-based survey was distributed to the American Association of Physicists in Medicine (AAPM) e-mail membership list, with a follow-up e-mail sent two weeks later. The survey included questions about ethics/professionalism education, direct personal knowledge of ethically questionable practices in clinical care, research, education (teaching and mentoring), and professionalism, respondents' assessment of their ability to address ethical/professional dilemmas, and demographics. For analysis, reports of unethical or ethically questionable practices or behaviors by approximately 40% or more of respondents were classified as "frequent." Partial or complete responses were received from 18% (1394/7708) of AAPM members. Overall, 60% (827/1377) of the respondents stated that they had not received ethics/professionalism education during their medical physics training. Respondents currently in training were more likely to state that they received instruction in ethics/professionalism (80%, 127/159) versus respondents who were post-training (35%, 401/1159). Respondents' preferred method of instruction in ethics/professionalism was structured periodic discussions involving both faculty and students/trainees. More than 90% (1271/1384) supported continuing education in ethics/professionalism and 75% (1043/1386) stated they would attend ethics/professionalism sessions at professional/scientific meetings. In the research setting, reports about ethically questionable authorship assignment were frequent (approximately 40%) whereas incidents of ethically questionable practices about human subjects protections were quite infrequent (5%). In the clinical setting, there was frequent recollection of incidents regarding lack of training, resources and skills, and error/incident reporting. In the educational setting, incidents of unethical or ethically questionable practices were only frequently recollected with respect to mentorship/guidance. With respect to professional conduct, favoritism, hostile work/learning environment, and maltreatment of subordinates and colleagues were frequently reported. A significantly larger proportion of women reported experiences with hostile work/learning environments, favoritism, poor mentorship, unfairness in educational settings, and concerns about student privacy and confidentiality. The survey found broad interest in ethics/professionalism topics and revealed that these topics were being integrated into the curriculum at many institutions. The incorporation of ethics and professionalism instruction into both graduate education and postgraduate training of medical physicists, and into their subsequent lifelong continuing education is important given the nontrivial number of medical physicists who had direct personal knowledge of unethical or ethically questionable incidents in clinical practice, research, education, and professionalism.

Ethics and professionalism in medical physics: A survey of AAPM members

PubMed Central

Ozturk, Naim; Armato, Samuel G.; Giger, Maryellen L.; Serago, Christopher F.; Ross, Lainie F.

2013-01-01

Purpose: To assess current education, practices, attitudes, and perceptions pertaining to ethics and professionalism in medical physics. Methods: A link to a web-based survey was distributed to the American Association of Physicists in Medicine (AAPM) e-mail membership list, with a follow-up e-mail sent two weeks later. The survey included questions about ethics/professionalism education, direct personal knowledge of ethically questionable practices in clinical care, research, education (teaching and mentoring), and professionalism, respondents’ assessment of their ability to address ethical/professional dilemmas, and demographics. For analysis, reports of unethical or ethically questionable practices or behaviors by approximately 40% or more of respondents were classified as “frequent.” Results: Partial or complete responses were received from 18% (1394/7708) of AAPM members. Overall, 60% (827/1377) of the respondents stated that they had not received ethics/professionalism education during their medical physics training. Respondents currently in training were more likely to state that they received instruction in ethics/professionalism (80%, 127/159) versus respondents who were post-training (35%, 401/1159). Respondents’ preferred method of instruction in ethics/professionalism was structured periodic discussions involving both faculty and students/trainees. More than 90% (1271/1384) supported continuing education in ethics/professionalism and 75% (1043/1386) stated they would attend ethics/professionalism sessions at professional/scientific meetings. In the research setting, reports about ethically questionable authorship assignment were frequent (approximately 40%) whereas incidents of ethically questionable practices about human subjects protections were quite infrequent (5%). In the clinical setting, there was frequent recollection of incidents regarding lack of training, resources and skills, and error/incident reporting. In the educational setting, incidents of unethical or ethically questionable practices were only frequently recollected with respect to mentorship/guidance. With respect to professional conduct, favoritism, hostile work/learning environment, and maltreatment of subordinates and colleagues were frequently reported. A significantly larger proportion of women reported experiences with hostile work/learning environments, favoritism, poor mentorship, unfairness in educational settings, and concerns about student privacy and confidentiality. Conclusions: The survey found broad interest in ethics/professionalism topics and revealed that these topics were being integrated into the curriculum at many institutions. The incorporation of ethics and professionalism instruction into both graduate education and postgraduate training of medical physicists, and into their subsequent lifelong continuing education is important given the nontrivial number of medical physicists who had direct personal knowledge of unethical or ethically questionable incidents in clinical practice, research, education, and professionalism. PMID:23556930

Group benefits in joint perceptual tasks-a review.

PubMed

Wahn, Basil; Kingstone, Alan; König, Peter

2018-05-12

In daily life, humans often perform perceptual tasks together to reach a shared goal. In these situations, individuals may collaborate (e.g., by distributing task demands) to perform the task better than when the task is performed alone (i.e., attain a group benefit). In this review, we identify the factors influencing if, and to what extent, a group benefit is attained and provide a framework of measures to assess group benefits in perceptual tasks. In particular, we integrate findings from two frequently investigated joint perceptual tasks: visuospatial tasks and decision-making tasks. For both task types, we find that an exchange of information between coactors is critical to improve joint performance. Yet, the type of exchanged information and how coactors collaborate differs between tasks. In visuospatial tasks, coactors exchange information about the performed actions to distribute task demands. In perceptual decision-making tasks, coactors exchange their confidence on their individual perceptual judgments to negotiate a joint decision. We argue that these differences can be explained by the task structure: coactors distribute task demands if a joint task allows for a spatial division and stimuli can be accurately processed by one individual. Otherwise, they perform the task individually and then integrate their individual judgments. © 2018 New York Academy of Sciences.

Radiology metrics for safe use and regulatory compliance with CT imaging

NASA Astrophysics Data System (ADS)

Paden, Robert; Pavlicek, William

2018-03-01

The MACRA Act creates a Merit-Based Payment System, with monitoring patient exposure from CT providing one possible quality metric for meeting merit requirements. Quality metrics are also required by The Joint Commission, ACR, and CMS as facilities are tasked to perform reviews of CT irradiation events outside of expected ranges, review protocols for appropriateness, and validate parameters for low dose lung cancer screening. In order to efficiently collect and analyze irradiation events and associated DICOM tags, all clinical CT devices were DICOM connected to a parser which extracted dose related information for storage into a database. Dose data from every exam is compared to the appropriate external standard exam type. AAPM recommended CTDIvol values for head and torso, adult and pediatrics, coronary and perfusion exams are used for this study. CT doses outside the expected range were automatically formatted into a report for analysis and review documentation. CT Technologist textual content, the reason for proceeding with an irradiation above the recommended threshold, is captured for inclusion in the follow up reviews by physics staff. The use of a knowledge based approach in labeling individual protocol and device settings is a practical solution resulting in efficiency of analysis and review. Manual methods would require approximately 150 person-hours for our facility, exclusive of travel time and independent of device availability. An efficiency of 89% time savings occurs through use of this informatics tool including a low dose CT comparison review and low dose lung cancer screening requirements set forth by CMS.

Speech Motor Sequence Learning: Effect of Parkinson Disease and Normal Aging on Dual-Task Performance.

PubMed

Whitfield, Jason A; Goberman, Alexander M

2017-06-22

Everyday communication is carried out concurrently with other tasks. Therefore, determining how dual tasks interfere with newly learned speech motor skills can offer insight into the cognitive mechanisms underlying speech motor learning in Parkinson disease (PD). The current investigation examines a recently learned speech motor sequence under dual-task conditions. A previously learned sequence of 6 monosyllabic nonwords was examined using a dual-task paradigm. Participants repeated the sequence while concurrently performing a visuomotor task, and performance on both tasks was measured in single- and dual-task conditions. The younger adult group exhibited little to no dual-task interference on the accuracy and duration of the sequence. The older adult group exhibited variability in dual-task costs, with the group as a whole exhibiting an intermediate, though significant, amount of dual-task interference. The PD group exhibited the largest degree of bidirectional dual-task interference among all the groups. These data suggest that PD affects the later stages of speech motor learning, as the dual-task condition interfered with production of the recently learned sequence beyond the effect of normal aging. Because the basal ganglia is critical for the later stages of motor sequence learning, the observed deficits may result from the underlying neural dysfunction associated with PD.

KENNEDY SPACE CENTER, FLA. - The Stafford-Covey Return to Flight Task Group (SCTG) visits the Columbia Debris Hangar . Chairing the task group are Richard O. Covey (third from right), former Space Shuttle commander, and Thomas P. Stafford (fourth from right), Apollo commander. Chartered by NASA Administrator Sean O’Keefe, the task group will perform an independent assessment of NASA’s implementation of the final recommendations by the Columbia Accident Investigation Board.

NASA Image and Video Library

2003-08-05

KENNEDY SPACE CENTER, FLA. - The Stafford-Covey Return to Flight Task Group (SCTG) visits the Columbia Debris Hangar . Chairing the task group are Richard O. Covey (third from right), former Space Shuttle commander, and Thomas P. Stafford (fourth from right), Apollo commander. Chartered by NASA Administrator Sean O’Keefe, the task group will perform an independent assessment of NASA’s implementation of the final recommendations by the Columbia Accident Investigation Board.

Improving multi-tasking ability through action videogames.

PubMed

Chiappe, Dan; Conger, Mark; Liao, Janet; Caldwell, J Lynn; Vu, Kim-Phuong L

2013-03-01

The present study examined whether action videogames can improve multi-tasking in high workload environments. Two groups with no action videogame experience were pre-tested using the Multi-Attribute Task Battery (MATB). It consists of two primary tasks; tracking and fuel management, and two secondary tasks; systems monitoring and communication. One group served as a control group, while a second played action videogames a minimum of 5 h a week for 10 weeks. Both groups returned for a post-assessment on the MATB. We found the videogame treatment enhanced performance on secondary tasks, without interfering with the primary tasks. Our results demonstrate action videogames can increase people's ability to take on additional tasks by increasing attentional capacity. Copyright © 2012 Elsevier Ltd and The Ergonomics Society. All rights reserved.

78 FR 15110 - Aviation Rulemaking Advisory Committee; Engine Bird Ingestion Requirements-New Task

Federal Register 2010, 2011, 2012, 2013, 2014

2013-03-08

...: During the bird-ingestion rulemaking database (BRDB) working group`s reevaluation of the current engine... engine core ingestion. If the BRDB working group`s reevaluation determines that such requirements are... Task ARAC accepted the task and will establish the Engine Harmonization Working Group (EHWG), under the...

Task-independent effects are potential confounders in longitudinal imaging studies of learning in schizophrenia.

PubMed

Korostil, Michele; Fatima, Zainab; Kovacevic, Natasha; Menon, Mahesh; McIntosh, Anthony Randal

2016-01-01

Learning impairment is a core deficit in schizophrenia that impacts on real-world functioning and yet, elucidating its underlying neural basis remains a challenge. A key issue when interpreting learning-task experiments is that task-independent changes may confound interpretation of task-related signal changes in neuroimaging studies. The nature of these task-independent changes in schizophrenia is unknown. Therefore, we examined task-independent "time effects" in a group of participants with schizophrenia contrasted with healthy participants in a longitudinal fMRI learning-experiment designed to allow for examination of non-specific effects of time. Flanking the learning portions of the experiment with a task-of-no-interest allowed us to extract task-independent BOLD changes. Task-independent effects occurred in both groups, but were more robust in the schizophrenia group. There was a significant interaction effect between group and time in a distributed activity pattern that included inferior and superior temporal regions, frontal areas (left anterior insula and superior medial gyri), and parietal areas (posterior cingulate cortices and precuneus). This pattern showed task-independent linear decrease in BOLD amplitude over the two scanning sessions for the schizophrenia group, but showed either opposite effect or no activity changes for the control group. There was a trend towards a correlation between task-independent effects and the presence of more negative symptoms in the schizophrenia group. The strong interaction between group and time suggests that both the scanning experience as a whole and the transition between task-types evokes a different response in persons with schizophrenia and may confound interpretation of learning-related longitudinal imaging experiments if not explicitly considered.

Task-independent effects are potential confounders in longitudinal imaging studies of learning in schizophrenia

PubMed Central

Korostil, Michele; Fatima, Zainab; Kovacevic, Natasha; Menon, Mahesh; McIntosh, Anthony Randal

2015-01-01

Learning impairment is a core deficit in schizophrenia that impacts on real-world functioning and yet, elucidating its underlying neural basis remains a challenge. A key issue when interpreting learning-task experiments is that task-independent changes may confound interpretation of task-related signal changes in neuroimaging studies. The nature of these task-independent changes in schizophrenia is unknown. Therefore, we examined task-independent “time effects” in a group of participants with schizophrenia contrasted with healthy participants in a longitudinal fMRI learning-experiment designed to allow for examination of non-specific effects of time. Flanking the learning portions of the experiment with a task-of-no-interest allowed us to extract task-independent BOLD changes. Task-independent effects occurred in both groups, but were more robust in the schizophrenia group. There was a significant interaction effect between group and time in a distributed activity pattern that included inferior and superior temporal regions, frontal areas (left anterior insula and superior medial gyri), and parietal areas (posterior cingulate cortices and precuneus). This pattern showed task-independent linear decrease in BOLD amplitude over the two scanning sessions for the schizophrenia group, but showed either opposite effect or no activity changes for the control group. There was a trend towards a correlation between task-independent effects and the presence of more negative symptoms in the schizophrenia group. The strong interaction between group and time suggests that both the scanning experience as a whole and the transition between task-types evokes a different response in persons with schizophrenia and may confound interpretation of learning-related longitudinal imaging experiments if not explicitly considered. PMID:26759790

Students' Perceptions of Motivational Climate and Enjoyment in Finnish Physical Education: A Latent Profile Analysis.

PubMed

Jaakkola, Timo; Wang, C K John; Soini, Markus; Liukkonen, Jarmo

2015-09-01

The purpose of this study was to identify student clusters with homogenous profiles in perceptions of task- and ego-involving, autonomy, and social relatedness supporting motivational climate in school physical education. Additionally, we investigated whether different motivational climate groups differed in their enjoyment in PE. Participants of the study were 2 594 girls and 1 803 boys, aged 14-15 years. Students responded to questionnaires assessing their perception of motivational climate and enjoyment in physical education. Latent profile analyses produced a five-cluster solution labeled 1) 'low autonomy, relatedness, task, and moderate ego climate' group', 2) 'low autonomy, relatedness, and high task and ego climate, 3) 'moderate autonomy, relatedness, task and ego climate' group 4) 'high autonomy, relatedness, task, and moderate ego climate' group, and 5) 'high relatedness and task but moderate autonomy and ego climate' group. Analyses of variance showed that students in clusters 4 and 5 perceived the highest level of enjoyment whereas students in cluster 1 experienced the lowest level of enjoyment. The results showed that the students' perceptions of various motivational climates created differential levels of enjoyment in PE classes. Key pointsLatent profile analyses produced a five-cluster solution labeled 1) 'low autonomy, relatedness, task, and moderate ego climate' group', 2) 'low autonomy, relatedness, and high task and ego climate, 3) 'moderate autonomy, relatedness, task and ego climate' group 4) 'high autonomy, relatedness, task, and moderate ego climate' group, and 5) 'high relatedness and task but moderate autonomy and ego climate' group.Analyses of variance showed that clusters 4 and 5 perceived the highest level of enjoyment whereas cluster 1 experienced the lowest level of enjoyment. The results showed that the students' perceptions of motivational climate create differential levels of enjoyment in PE classes.

Thrive or overload? The effect of task complexity on novices' simulation-based learning.

PubMed

Haji, Faizal A; Cheung, Jeffrey J H; Woods, Nicole; Regehr, Glenn; de Ribaupierre, Sandrine; Dubrowski, Adam

2016-09-01

Fidelity is widely viewed as an important element of simulation instructional design based on its purported relationship with transfer of learning. However, higher levels of fidelity may increase task complexity to a point at which novices' cognitive resources become overloaded. In this experiment, we investigate the effects of variations in task complexity on novices' cognitive load and learning during simulation-based procedural skills training. Thirty-eight medical students were randomly assigned to simulation training on a simple or complex lumbar puncture (LP) task. Participants completed four practice trials on this task (skill acquisition). After 10 days of rest, all participants completed one additional trial on their assigned task (retention) and one trial on a 'very complex' simulation designed to be similar to the complex task (transfer). We assessed LP performance and cognitive load on each trial using multiple measures. In both groups, LP performance improved significantly during skill acquisition (p ≤ 0.047, f = 0.29-0.96) and was maintained at retention. The simple task group demonstrated superior performance compared with the complex task group throughout these phases (p ≤ 0.002, d = 1.13-2.31). Cognitive load declined significantly in the simple task group (p < 0.009, f = 0.48-0.76), but not in the complex task group during skill acquisition, and remained lower at retention (p ≤ 0.024, d = 0.78-1.39). Between retention and transfer, LP performance declined and cognitive load increased in the simple task group, whereas both remained stable in the complex task group. At transfer, no group differences were observed in LP performance and cognitive load, except that the simple task group made significantly fewer breaches of sterility (p = 0.023, d = 0.80). Reduced task complexity was associated with superior LP performance and lower cognitive load during skill acquisition and retention, but mixed results on transfer to a more complex task. These results indicate that task complexity is an important factor that may mediate (via cognitive overload) the relationship between instructional design elements (e.g. fidelity) and simulation-based learning outcomes. © 2016 John Wiley & Sons Ltd and The Association for the Study of Medical Education.

WE-G-BRB-08: TG-51 Calibration of First Commercial MRI-Guided IMRT System in the Presence of 0.35 Tesla Magnetic Field.

PubMed

Goddu, S; Green, O Pechenaya; Mutic, S

2012-06-01

The first real-time-MRI-guided radiotherapy system has been installed in a clinic and it is being evaluated. Presence of magnetic field (MF) during radiation output calibration may have implications on ionization measurements and there is a possibility that standard calibration protocols may not be suitable for dose measurements for such devices. In this study, we evaluated whether a standard calibration protocol (AAPM- TG-51) is appropriate for absolute dose measurement in presence of MF. Treatment delivery of the ViewRay (VR) system is via three 15,000Ci Cobalt-60 heads positioned 120-degrees apart and all calibration measurements were done in the presence of 0.35T MF. Two ADCL- calibrated ionization-chambers (Exradin A12, A16) were used for TG-51 calibration. Chambers were positioned at 5-cm depth, (SSD=105cm: VR's isocenter), and the MLC leaves were shaped to a 10.5cm × 10.5 cm field size. Percent-depth-dose (PDD) measurements were performed for 5 and 10 cm depths. Individual output of each head was measured using the AAPM- TG51 protocol. Calibration accuracy for each head was subsequently verified by Radiological Physics Center (RPC) TLD measurements. Measured ion-recombination (Pion) and polarity (Ppol) correction factors were less-than 1.002 and 1.006, respectively. Measured PDDs agreed with BJR-25 within ±0.2%. Maximum dose rates for the reference field size at VR's isocenter for heads 1, 2 and 3 were 1.445±0.005, 1.446±0.107, 1.431±0.006 Gy/minute, respectively. Our calibrations agreed with RPC- TLD measurements within ±1.3%, ±2.6% and ±2.0% for treatment-heads 1, 2 and 3, respectively. At the time of calibration, mean activity of the Co-60 sources was 10,800Ci±0.1%. This study shows that the TG- 51 calibration is feasible in the presence of 0.35T MF and the measurement agreement is within the range of results obtainable for conventional treatment machines. Drs. Green, Goddu, and Mutic served as scientific consultants for ViewRay, Inc. Dr. Mutic is on the clinical focus group for ViewRay, Inc., and his spouse holds shares in ViewRay, Inc. © 2012 American Association of Physicists in Medicine.

KENNEDY SPACE CENTER, FLA. - In the Columbia Debris Hangar, members of the Stafford-Covey Return to Flight Task Group (SCTG) look at tiles recovered. Chairing the task group are Richard O. Covey, former Space Shuttle commander, and Thomas P. Stafford (center), Apollo commander. Chartered by NASA Administrator Sean O’Keefe, the task group will perform an independent assessment of NASA’s implementation of the final recommendations by the Columbia Accident Investigation Board.

NASA Image and Video Library

2003-08-05

KENNEDY SPACE CENTER, FLA. - In the Columbia Debris Hangar, members of the Stafford-Covey Return to Flight Task Group (SCTG) look at tiles recovered. Chairing the task group are Richard O. Covey, former Space Shuttle commander, and Thomas P. Stafford (center), Apollo commander. Chartered by NASA Administrator Sean O’Keefe, the task group will perform an independent assessment of NASA’s implementation of the final recommendations by the Columbia Accident Investigation Board.

KENNEDY SPACE CENTER, FLA. - In the Columbia Debris Hangar, members of the Stafford-Covey Return to Flight Task Group (SCTG) inspect some of the debris. Chairing the task group are Richard O. Covey, former Space Shuttle commander, and Thomas P. Stafford (fourth from left), Apollo commander. Chartered by NASA Administrator Sean O’Keefe, the task group will perform an independent assessment of NASA’s implementation of the final recommendations by the Columbia Accident Investigation Board.

NASA Image and Video Library

2003-08-05

KENNEDY SPACE CENTER, FLA. - In the Columbia Debris Hangar, members of the Stafford-Covey Return to Flight Task Group (SCTG) inspect some of the debris. Chairing the task group are Richard O. Covey, former Space Shuttle commander, and Thomas P. Stafford (fourth from left), Apollo commander. Chartered by NASA Administrator Sean O’Keefe, the task group will perform an independent assessment of NASA’s implementation of the final recommendations by the Columbia Accident Investigation Board.

Usefulness of near-infrared spectroscopy to detect brain dysfunction in children with autism spectrum disorder when inferring the mental state of others.

PubMed

Iwanaga, Ryoichiro; Tanaka, Goro; Nakane, Hideyuki; Honda, Sumihisa; Imamura, Akira; Ozawa, Hiroki

2013-05-01

The purpose of this study was to examine the usefulness of near-infrared spectroscopy (NIRS) for identifying abnormalities in prefrontal brain activity in children with autism spectrum disorders (ASD) as they inferred the mental states of others. The subjects were 16 children with ASD aged between 8 and 14 years and 16 age-matched healthy control children. Oxygenated hemoglobin concentration was measured in the subject's prefrontal brain region on NIRS during tasks expressing a person's mental state (MS task) and expressing an object's characteristics (OC task). There was a significant main effect of group (ASD vs control), with the control group having more activity than the ASD group. But there was no significant main effect of task (MS task vs OC task) or hemisphere (right vs left). Significant interactions of task and group were found, with the control group showing more activity than the ASD group during the MS task relative to the OC task. NIRS showed that there was lower activity in the prefrontal brain area when children with ASD performed MS tasks. Therefore, clinicians might be able to use NIRS and these tasks for conveniently detecting brain dysfunction in children with ASD related to inferring mental states, in the clinical setting. © 2013 The Authors. Psychiatry and Clinical Neurosciences © 2013 Japanese Society of Psychiatry and Neurology.

MO-E-17A-08: Attenuation-Based Size Adjusted, Scanner-Independent Organ Dose Estimates for Head CT Exams: TG 204 for Head CT

DOE Office of Scientific and Technical Information (OSTI.GOV)

McMillan, K; Bostani, M; Cagnon, C

Purpose: AAPM Task Group 204 described size specific dose estimates (SSDE) for body scans. The purpose of this work is to use a similar approach to develop patient-specific, scanner-independent organ dose estimates for head CT exams using an attenuation-based size metric. Methods: For eight patient models from the GSF family of voxelized phantoms, dose to brain and lens of the eye was estimated using Monte Carlo simulations of contiguous axial scans for 64-slice MDCT scanners from four major manufacturers. Organ doses were normalized by scannerspecific 16 cm CTDIvol values and averaged across all scanners to obtain scanner-independent CTDIvol-to-organ-dose conversion coefficientsmore » for each patient model. Head size was measured at the first slice superior to the eyes; patient perimeter and effective diameter (ED) were measured directly from the GSF data. Because the GSF models use organ identification codes instead of Hounsfield units, water equivalent diameter (WED) was estimated indirectly. Using the image data from 42 patients ranging from 2 weeks old to adult, the perimeter, ED and WED size metrics were obtained and correlations between each metric were established. Applying these correlations to the GSF perimeter and ED measurements, WED was calculated for each model. The relationship between the various patient size metrics and CTDIvol-to-organ-dose conversion coefficients was then described. Results: The analysis of patient images demonstrated the correlation between WED and ED across a wide range of patient sizes. When applied to the GSF patient models, an exponential relationship between CTDIvol-to-organ-dose conversion coefficients and the WED size metric was observed with correlation coefficients of 0.93 and 0.77 for the brain and lens of the eye, respectively. Conclusion: Strong correlation exists between CTDIvol normalized brain dose and WED. For the lens of the eye, a lower correlation is observed, primarily due to surface dose variations. Funding Support: Siemens-UCLA Radiology Master Research Agreement; Disclosures - Michael McNitt-Gray: Institutional Research Agreement, Siemens AG; Research Support, Siemens AG; Consultant, Flaherty Sensabaugh Bonasso PLLC; Consultant, Fulbright and Jaworski.« less

In vivo dosimetry using a single diode for megavoltage photon beam radiotherapy: implementation and response characterization.

PubMed

Colussi, V C; Beddar, A S; Kinsella, T J; Sibata, C H

2001-01-01

The AAPM Task Group 40 reported that in vivo dosimetry can be used to identify major deviations in treatment delivery in radiation therapy. In this paper, we investigate the feasibility of using one single diode to perform in vivo dosimetry in the entire radiotherapeutic energy range regardless of its intrinsic buildup material. The only requirement on diode selection would be to choose a diode with the adequate build up to measure the highest beam energy. We have tested the new diodes from Sun Nuclear Corporation (called QED and ISORAD-p--both p-type) for low-, intermediate-, and high-energy range. We have clinically used both diode types to monitor entrance doses. In general, we found that the dose readings from the ISORAD (p-type) are closer of the dose expected than QED diodes in the clinical setting. In this paper we report on the response of these newly available ISORAD (p-type) diode detectors with respect to certain radiation field parameters such as source-to-surface distance, field size, wedge beam modifiers, as well as other parameters that affect detector characteristics (temperature and detector-beam orientation). We have characterized the response of the high-energy ISORAD (p-type) diode in the low- (1-4 MV), intermediate- (6-12 MV), and high-energy (15-25 MV) range. Our results showed that the total variation of the response of high-energy ISORAD (p-type) diodes to all the above parameters are within +/-5% in most encountered clinical patient treatment setups in the megavoltage photon beam radiotherapy. The usage of the high-energy buildup diode has the additional benefit of amplifying the response of the diode reading in case the wrong energy is used for patient treatment. In the light of these findings, we have since then switched to using only one single diode type, namely the "red" diode; manufacturer designation of the ISORAD (p-type) high-energy (15-25 MV) range diode, for all energies in our institution and satellites.

In vivo dosimetry using a single diode for megavoltage photon beam radiotherapy: Implementation and response characterization

PubMed Central

Beddar, A. Sam; Kinsella, Timothy J.; Sibata, Claudio H.

2001-01-01

The AAPM Task Group 40 reported that in vivo dosimetry can be used to identify major deviations in treatment delivery in radiation therapy. In this paper, we investigate the feasibility of using one single diode to perform in vivo dosimetry in the entire radiotherapeutic energy range regardless of its intrinsic buildup material. The only requirement on diode selection would be to choose a diode with the adequate build up to measure the highest beam energy. We have tested the new diodes from Sun Nuclear Corporation (called QED and ISORAD‐p–both p‐type) for low‐, intermediate‐, and high‐energy range. We have clinically used both diode types to monitor entrance doses. In general, we found that the dose readings from the ISORAD (p‐type) are closer of the dose expected than QED diodes in the clinical setting. In this paper we report on the response of these newly available ISORAD (p‐type) diode detectors with respect to certain radiation field parameters such as source‐to‐surface distance, field size, wedge beam modifiers, as well as other parameters that affect detector characteristics (temperature and detector‐beam orientation). We have characterized the response of the high‐energy ISORAD (p‐type) diode in the low‐ (1–4 MV), intermediate‐ (6–12 MV), and high‐energy (15–25 MV) range. Our results showed that the total variation of the response of high‐energy ISORAD (p‐type) diodes to all the above parameters are within ±5% in most encountered clinical patient treatment setups in the megavoltage photon beam radiotherapy. The usage of the high‐energy buildup diode has the additional benefit of amplifying the response of the diode reading in case the wrong energy is used for patient treatment. In the light of these findings, we have since then switched to using only one single diode type, namely the “red” diode; manufacturer designation of the ISORAD (p‐type) high‐energy (15–25 MV) range diode, for all energies in our institution and satellites. PACS number(s): 87.66.–a, 87.53.–j PMID:11686742

Episcleral eye plaque dosimetry comparison for the Eye Physics EP917 using Plaque Simulator and Monte Carlo simulation

PubMed Central

Amoush, Ahmad; Wilkinson, Douglas A.

2015-01-01

This work is a comparative study of the dosimetry calculated by Plaque Simulator, a treatment planning system for eye plaque brachytherapy, to the dosimetry calculated using Monte Carlo simulation for an Eye Physics model EP917 eye plaque. Monte Carlo (MC) simulation using MCNPX 2.7 was used to calculate the central axis dose in water for an EP917 eye plaque fully loaded with 17 IsoAid Advantage  125I seeds. In addition, the dosimetry parameters Λ, gL(r), and F(r,θ) were calculated for the IsoAid Advantage model IAI‐125  125I seed and benchmarked against published data. Bebig Plaque Simulator (PS) v5.74 was used to calculate the central axis dose based on the AAPM Updated Task Group 43 (TG‐43U1) dose formalism. The calculated central axis dose from MC and PS was then compared. When the MC dosimetry parameters for the IsoAid Advantage  125I seed were compared with the consensus values, Λ agreed with the consensus value to within 2.3%. However, much larger differences were found between MC calculated gL(r) and F(r,θ) and the consensus values. The differences between MC‐calculated dosimetry parameters are much smaller when compared with recently published data. The differences between the calculated central axis absolute dose from MC and PS ranged from 5% to 10% for distances between 1 and 12 mm from the outer scleral surface. When the dosimetry parameters for the  125I seed from this study were used in PS, the calculated absolute central axis dose differences were reduced by 2.3% from depths of 4 to 12 mm from the outer scleral surface. We conclude that PS adequately models the central dose profile of this plaque using its defaults for the IsoAid model IAI‐125 at distances of 1 to 7 mm from the outer scleral surface. However, improved dose accuracy can be obtained by using updated dosimetry parameters for the IsoAid model IAI‐125  125I seed. PACS number: 87.55.K‐ PMID:26699577

The impact of water temperature on the measurement of absolute dose

NASA Astrophysics Data System (ADS)

Islam, Naveed Mehdi

To standardize reference dosimetry in radiation therapy, Task Group 51 (TG 51) of American Association of Physicist's in Medicine (AAPM) recommends that dose calibration measurements be made in a water tank at a depth of 10 cm and at a reference geometry. Methodologies are provided for calculating various correction factors to be applied in calculating the absolute dose. However the protocol does not specify the water temperature to be used. In practice, the temperature of water during dosimetry may vary considerably between independent sessions and different centers. In this work the effect of water temperature on absolute dosimetry has been investigated. Density of water varies with temperature, which in turn may impact the beam attenuation and scatter properties. Furthermore, due to thermal expansion or contraction air volume inside the chamber may change. All of these effects can result in a change in the measurement. Dosimetric measurements were made using a Farmer type ion chamber on a Varian Linear Accelerator for 6 MV and 23 MV photon energies for temperatures ranging from 10 to 40 °C. A thermal insulation was designed for the water tank in order to maintain relatively stable temperature over the duration of the experiment. Dose measured at higher temperatures were found to be consistently higher by a very small magnitude. Although the differences in dose were less than the uncertainty in each measurement, a linear regression of the data suggests that the trend is statistically significant with p-values of 0.002 and 0.013 for 6 and 23 MV beams respectively. For a 10 degree difference in water phantom temperatures, which is a realistic deviation across clinics, the final calculated reference dose can differ by 0.24% or more. To address this effect, first a reference temperature (e.g.22 °C) can be set as the standard; subsequently a correction factor can be implemented for deviations from this reference. Such a correction factor is expected to be of similar magnitude as existing TG 51 recommended correction factors.

SU-F-P-54: Guidelines to Check Image Registration QA of a Clinical Deformation Registration Software: A Single Institution Preliminary Study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gill, G; Souri, S; Rea, A

Purpose: The objective of this study is to verify and analyze the accuracy of a clinical deformable image registration (DIR) software. Methods: To test clinical DIR software qualitatively and quantitatively, we focused on lung radiotherapy and analyzed a single (Lung) patient CT scan. Artificial anatomical changes were applied to account for daily variations during the course of treatment including the planning target volume (PTV) and organs at risk (OAR). The primary CT (pCT) and the structure set (pST) was deformed with commercial tool (ImSimQA-Oncology Systems Limited) and after artificial deformation (dCT and dST) sent to another commercial tool (VelocityAI-Varian Medicalmore » Systems). In Velocity, the deformed CT and structures (dCT and dST) were inversely deformed back to original primary CT (dbpCT and dbpST). We compared the dbpST and pST structure sets using similarity metrics. Furthermore, a binary deformation field vector (BDF) was created and sent to ImSimQA software for comparison with known “ground truth” deformation vector fields (DVF). Results: An image similarity comparison was made by using “ground truth” DVF and “deformed output” BDF with an output of normalized “cross correlation (CC)” and “mutual information (MI)” in ImSimQA software. Results for the lung case were MI=0.66 and CC=0.99. The artificial structure deformation in both pST and dbpST was analyzed using DICE coefficient, mean distance to conformity (MDC) and deformation field error volume histogram (DFEVH) by comparing them before and after inverse deformation. We have noticed inadequate structure match for CTV, ITV and PTV due to close proximity of heart and overall affected by lung expansion. Conclusion: We have seen similarity between pCT and dbpCT but not so well between pST and dbpST, because of inadequate structure deformation in clinical DIR system. This system based quality assurance test will prepare us for adopting the guidelines of upcoming AAPM task group 132 protocol.« less

Radiation dermatitis caused by a bolus effect from an abdominal compression device

DOE Office of Scientific and Technical Information (OSTI.GOV)

Connor, Michael; Wei, Randy L.; Yu, Suhong

American Association of Physicists in Medicine (AAPM) Task Group 176 evaluated the dosimetric effects caused by couch tops and immobilization devices. The report analyzed the extensive physics-based literature on couch tops, stereotactic body radiation therapy (SBRT) frames, and body immobilization bags, while noting the scarcity of clinical reports of skin toxicity because of external devices. Here, we present a clinical case report of grade 1 abdominal skin toxicity owing to an abdominal compression device. We discuss the dosimetric implications of the utilized treatment plan as well as post hoc alternative plans and quantify differences in attenuation and skin dose/build-up betweenmore » the device, a lower-density alternative device, and an open field. The description of the case includes a 66-year-old male with HER2 amplified poorly differentiated distal esophageal adenocarcinoma treated with neoadjuvant chemo-radiation and the use of an abdominal compression device. Radiation was delivered using volumetric modulated arc therapy (VMAT) with 2 arcs using abdominal compression and image guidance. The total dose was 50.4 Gy delivered over 40 elapsed days. With 2 fractions remaining, the patient developed dermatitis in the area of the compression device. The original treatment plan did not include a contour of the device. Alternative post hoc treatment plans were generated, one to contour the device and a second with anterior avoidance. In conclusion, replanning with the device contoured revealed the bolus effect. The skin dose increased from 27 to 36 Gy. planned target volume (PTV) coverage at 45 Gy was reduced to 76.5% from 95.8%. The second VMAT treatment plan with an anterior avoidance sector and more oblique beam angles maintained PTV coverage and spared the anterior wall, however at the expense of substantially increased dose to lung. This case report provides an important reminder of the bolus effect from external devices such as abdominal compression. Special consideration must be given to contour and/or avoiding beam entrance to the device, and to the use of such devices in patients who may have heightened radiosensitivity, such as those who are human immunodeficiency virus (HIV)–positive.« less

SU-F-T-305: Clinical Effects of Dosimetric Leaf Gap (DLG) Values Between Matched Varian Truebeam (TB) Linacs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mihailidis, D; Mallah, J; Zhu, D

2016-06-15

Purpose: The dosimetric leaf gap (DLG) is an important parameter to be measured for dynamic beam delivery of modern linacs, like the Varian Truebeam (TB). The clinical effects of DLG-values on IMRT and/or VMAT commissioning of two “matched” TB linacs will be presented.Methods and Materials: The DLG values on two TB linacs were measured for all energy modalities (filtered and FFF-modes) as part of the dynamic delivery mode commissioning (IMRT and/or VMAT. After the standard beam data was modeled in eclipse treatment planning system (TPS) and validated, IMRT validation was performed based on TG1191 benchmark, IROC Head-Neck (H&N) phantom andmore » sample of clinical cases, all measured on both linacs. Although there was a single-set of data entered in the TPS, a noticeable difference was observed for the DLG-values between the linacs. The TG119, IROC phantom and selected patient plans were furnished with DLG-values of TB1 for both linacs and the delivery was performed on both TB linacs for comparison. Results: The DLG values of TB1 was first used for both linacs to perform the testing comparisons. The QA comparison of TG119 plans revealed a great dependence of the results to the DLG-values used for the linac for all energy modalities studied, especially when moving from 3%/3mm to 2%/2mm γ-analysis. Conclusion: The DLG-values have a definite influence on the dynamic dose, delivery that increases with the plan complexity. We recommend that the measured DLG-values are assigned to each of the “matched” linacs, even if a single set of beam data describes multiple linacs. The user should perform a detail test of the dynamic delivery of each linac based on end-to-end benchmark suites like TG119 and IROC phantoms.1Ezzel G., et al., “IMRT commissioning: Multiple institution planning and dosimetry comparisons, a report from AAPM Task Group 119.” Med. Phys. 36:5359–5373 (2009). partly supported by CAMC Cancer Center and Alliance Oncology.« less

SU-E-J-87: Building Deformation Error Histogram and Quality Assurance of Deformable Image Registration.

PubMed

Park, S B; Kim, H; Yao, M; Ellis, R; Machtay, M; Sohn, J W

2012-06-01

To quantify the systematic error of a Deformable Image Registration (DIR) system and establish Quality Assurance (QA) procedure. To address the shortfall of landmark approach which it is only available at the significant visible feature points, we adapted a Deformation Vector Map (DVM) comparison approach. We used two CT image sets (R and T image sets) taken for the same patient at different time and generated a DVM, which includes the DIR systematic error. The DVM was calculated using fine-tuned B-Spline DIR and L-BFGS optimizer. By utilizing this DVM we generated R' image set to eliminate the systematic error in DVM,. Thus, we have truth data set, R' and T image sets, and the truth DVM. To test a DIR system, we use R' and T image sets to a DIR system. We compare the test DVM to the truth DVM. If there is no systematic error, they should be identical. We built Deformation Error Histogram (DEH) for quantitative analysis. The test registration was performed with an in-house B-Spline DIR system using a stochastic gradient descent optimizer. Our example data set was generated with a head and neck patient case. We also tested CT to CBCT deformable registration. We found skin regions which interface with the air has relatively larger errors. Also mobile joints such as shoulders had larger errors. Average error for ROIs were as follows; CTV: 0.4mm, Brain stem: 1.4mm, Shoulders: 1.6mm, and Normal tissues: 0.7mm. We succeeded to build DEH approach to quantify the DVM uncertainty. Our data sets are available for testing other systems in our web page. Utilizing DEH, users can decide how much systematic error they would accept. DEH and our data can be a tool for an AAPM task group to compose a DIR system QA guideline. This project is partially supported by the Agency for Healthcare Research and Quality (AHRQ) grant 1R18HS017424-01A2. © 2012 American Association of Physicists in Medicine.

Report of the AAPM Task Group No. 105: Issues associated with clinical implementation of Monte Carlo-based photon and electron external beam treatment planning.

PubMed

Chetty, Indrin J; Curran, Bruce; Cygler, Joanna E; DeMarco, John J; Ezzell, Gary; Faddegon, Bruce A; Kawrakow, Iwan; Keall, Paul J; Liu, Helen; Ma, C M Charlie; Rogers, D W O; Seuntjens, Jan; Sheikh-Bagheri, Daryoush; Siebers, Jeffrey V

2007-12-01

The Monte Carlo (MC) method has been shown through many research studies to calculate accurate dose distributions for clinical radiotherapy, particularly in heterogeneous patient tissues where the effects of electron transport cannot be accurately handled with conventional, deterministic dose algorithms. Despite its proven accuracy and the potential for improved dose distributions to influence treatment outcomes, the long calculation times previously associated with MC simulation rendered this method impractical for routine clinical treatment planning. However, the development of faster codes optimized for radiotherapy calculations and improvements in computer processor technology have substantially reduced calculation times to, in some instances, within minutes on a single processor. These advances have motivated several major treatment planning system vendors to embark upon the path of MC techniques. Several commercial vendors have already released or are currently in the process of releasing MC algorithms for photon and/or electron beam treatment planning. Consequently, the accessibility and use of MC treatment planning algorithms may well become widespread in the radiotherapy community. With MC simulation, dose is computed stochastically using first principles; this method is therefore quite different from conventional dose algorithms. Issues such as statistical uncertainties, the use of variance reduction techniques, the ability to account for geometric details in the accelerator treatment head simulation, and other features, are all unique components of a MC treatment planning algorithm. Successful implementation by the clinical physicist of such a system will require an understanding of the basic principles of MC techniques. The purpose of this report, while providing education and review on the use of MC simulation in radiotherapy planning, is to set out, for both users and developers, the salient issues associated with clinical implementation and experimental verification of MC dose algorithms. As the MC method is an emerging technology, this report is not meant to be prescriptive. Rather, it is intended as a preliminary report to review the tenets of the MC method and to provide the framework upon which to build a comprehensive program for commissioning and routine quality assurance of MC-based treatment planning systems.

The effect of single-task and dual-task balance exercise programs on balance performance in adults with osteoporosis: a randomized controlled preliminary trial.

PubMed

Konak, H E; Kibar, S; Ergin, E S

2016-11-01

Osteoporosis is a serious disease characterized by muscle weakness in the lower extremities, shortened length of trunk, and increased dorsal kyphosis leading to poor balance performance. Although balance impairment increases in adults with osteoporosis, falls and fall-related injuries have been shown to occur mainly during the dual-task performance. Several studies have shown that dual-task performance was improved with specific repetitive dual-task exercises. The aims of this study were to compare the effect of single- and dual-task balance exercise programs on static balance, dynamic balance, and activity-specific balance confidence in adults with osteoporosis and to assess the effectiveness of dual-task balance training on gait speed under dual-task conditions. Older adults (N = 42) (age range, 45-88 years) with osteoporosis were randomly assigned into two groups. Single-task balance training group was given single-task balance exercises for 4 weeks, whereas dual-task balance training group received dual-task balance exercises. Participants received 45-min individualized training session, three times a week. Static balance was evaluated by one-leg stance (OLS) and a kinesthetic ability trainer (KAT) device. Dynamic balance was measured by the Berg Balance Scale (BBS), Time Up and Go (TUG) test, and gait speed. Self-confidence was assessed with the Activities-specific Balance Confidence (ABC-6) scale. Assessments were performed at baseline and after the 4-week program. At the end of the treatment periods, KAT score, BBS score, time in OLS and TUG, gait speeds under single- and dual-task conditions, and ABC-6 scale scores improved significantly in all patients (p < 0.05). However, BBS and gait speeds under single- and dual-task conditions showed significantly greater improvement in the dual-task balance training group than in the single-task balance training group (p < 0.05). ABC-6 scale scores improved more in the single-task balance training group than in the dual-task balance training group (p < 0.05). A 4-week single- and dual-task balance exercise programs are effective in improving static balance, dynamic balance, and balance confidence during daily activities in older adults with osteoporosis. However, single- and dual-task gait speeds showed greater improvement following the application of a specific type of dual-task exercise programs. 24102014-2.

Effects of n-dominance and group composition on task efficiency in laboratory triads.

NASA Technical Reports Server (NTRS)

Lampkin, E. C.

1972-01-01

Task-oriented triads were formed into various homogeneous and heterogeneous combinations according to their scores on the n-dominance personality trait of the Edwards Personal Preference Schedule. Five group categories were used. The group task required a consensus decision on each trial. High cooperation and interdependence were reinforced by partially restricting the communication network. Results showed heterogeneous groups significantly better at organizing their group communication processes. They consequently performed the task more efficiently than homogeneous triads.

The Task and Relational Dimensions of Online Social Support.

PubMed

Beck, Stephenson J; Paskewitz, Emily A; Anderson, Whitney A; Bourdeaux, Renee; Currie-Mueller, Jenna

2017-03-01

Online support groups are attractive to individuals suffering from various types of mental and physical illness due to their accessibility, convenience, and comfort level. Individuals coping with depression, in particular, may seek social support online to avoid the stigma that accompanies face-to-face support groups. We explored how task and relational messages created social support in online depression support groups using Cutrona and Suhr's social support coding scheme and Bales's Interaction Process Analysis coding scheme. A content analysis revealed emotional support as the most common type of social support within the group, although the majority of messages were task rather than relational. Informational support consisted primarily of task messages, whereas network and esteem support were primarily relational messages. Specific types of task and relational messages were associated with different support types. Results indicate task messages dominated online depression support groups, suggesting the individuals who participate in these groups are interested in solving problems but may also experience emotional support when their uncertainty is reduced via task messages.

High and low schizotypal female subjects do not differ in spatial memory abilities in a virtual reality task.

PubMed

García-Montes, José Manuel; Noguera, Carmen; Alvarez, Dolores; Ruiz, Marina; Cimadevilla Redondo, José Manuel

2014-01-01

Schizotypy is a psychological construct related to schizophrenia. The exact relationship between both entities is not clear. In recent years, schizophrenia has been associated with hippocampal abnormalities and spatial memory problems. The aim of this study was to determine possible links between high schizotypy (HS) and low schizotypy (LS) and spatial abilities, using virtual reality tasks. We hypothesised that the HS group would exhibit a lower performance in spatial memory tasks than the LS group. Two groups of female students were formed according to their score on the ESQUIZO-Q-A questionnaire. HS and LS subjects were tested on two different tasks: the Boxes Room task, a spatial memory task sensitive to hippocampal alterations and a spatial recognition task. Data showed that both groups mastered both tasks. Groups differed in personality features but not in spatial performance. These results provide valuable information about the schizotypy-schizophrenia connections. Schizotypal subjects are not impaired on spatial cognition and, accordingly, the schizotypy-schizophrenia relationship is not straightforward.

The influence of a real job on upper limb performance in motor skill tests: which abilities are transferred?

PubMed

Giangiardi, Vivian Farahte; Alouche, Sandra Regina; de Freitas, Sandra Maria Sbeghen Ferreira; Pires, Raquel Simoni; Padula, Rosimeire Simprini

2018-06-01

To investigate whether the specificities of real jobs create distinctions in the performance of workers in different motor tests for the upper limbs, 24 participants were divided into two groups according to their specific job: fine and repetitive tasks and general tasks. Both groups reproduced tasks related to aiming movements, handling and strength of the upper limbs. There were no significant differences between groups in the dexterity and performance of aiming movements. However, the general tasks group had higher grip strength than the repetitive tasks group, demonstrating differences according to job specificity. The results suggest that a particular motor skill in a specific job cannot improve performance in other tasks with the same motor requirements. The transfer of the fine and gross motor skills from previous experience in a job-specific task is the basis for allocating training and guidance to workers.

Severe tinnitus and its effect on selective and divided attention.

PubMed

Stevens, Catherine; Walker, Gary; Boyer, Morten; Gallagher, Melinda

2007-05-01

The effect of chronic, severe tinnitus on two visual tasks was investigated. A general depletion of resources hypothesis states that overall performance would be impaired in a tinnitus group relative to a control group whereas a controlled processing hypothesis states that only tasks that are demanding, requiring strategic processes, are affected. Eleven participants who had experienced severe tinnitus for more than two years comprised the tinnitus group. A control group was matched for age and verbal IQ. Levels of anxiety, depression, and high frequency average hearing level were treated as covariates. Tasks consisted of the say-word (easy) and say-color (demanding) conditions of the Stroop task, a single (baseline) reaction time (RT) task, and dual tasks involving word reading or category naming while performing a concurrent RT task. Results supported the general depletion of resources hypothesis: RT of the tinnitus group was slower in both conditions of the Stroop task, and in the word reading and category naming conditions of the dual task. Differences were not attributable to high frequency average hearing level, anxiety, or depression.

Central as well as Peripheral Attentional Bottlenecks in Dual-Task Performance Activate Lateral Prefrontal Cortices

PubMed Central

Szameitat, André J.; Vanloo, Azonya; Müller, Hermann J.

2016-01-01

Human information processing suffers from severe limitations in parallel processing. In particular, when required to respond to two stimuli in rapid succession, processing bottlenecks may appear at central and peripheral stages of task processing. Importantly, it has been suggested that executive functions are needed to resolve the interference arising at such bottlenecks. The aims of the present study were to test whether central attentional limitations (i.e., bottleneck at the decisional response selection stage) as well as peripheral limitations (i.e., bottleneck at response initiation) both demand executive functions located in the lateral prefrontal cortex. For this, we re-analyzed two previous studies, in which a total of 33 participants performed a dual-task according to the paradigm of the psychological refractory period (PRP) during functional magnetic resonance imaging (fMRI). In one study (N = 17), the PRP task consisted of two two-choice response tasks known to suffer from a central bottleneck (CB group). In the other study (N = 16), the PRP task consisted of two simple-response tasks known to suffer from a peripheral bottleneck (PB group). Both groups showed considerable dual-task costs in form of slowing of the second response in the dual-task (PRP effect). Imaging results are based on the subtraction of both single-tasks from the dual-task within each group. In the CB group, the bilateral middle frontal gyri and inferior frontal gyri were activated. Higher activation in these areas was associated with lower dual-task costs. In the PB group, the right middle frontal and inferior frontal gyrus (IFG) were activated. Here, higher activation was associated with higher dual-task costs. In conclusion we suggest that central and peripheral bottlenecks both demand executive functions located in lateral prefrontal cortices (LPFC). Differences between the CB and PB groups with respect to the exact prefrontal areas activated and the correlational patterns suggest that the executive functions resolving interference at least partially differ between the groups. PMID:27014044

Dynamical signatures of isometric force control as a function of age, expertise, and task constraints.

PubMed

Vieluf, Solveig; Sleimen-Malkoun, Rita; Voelcker-Rehage, Claudia; Jirsa, Viktor; Reuter, Eva-Maria; Godde, Ben; Temprado, Jean-Jacques; Huys, Raoul

2017-07-01

From the conceptual and methodological framework of the dynamical systems approach, force control results from complex interactions of various subsystems yielding observable behavioral fluctuations, which comprise both deterministic (predictable) and stochastic (noise-like) dynamical components. Here, we investigated these components contributing to the observed variability in force control in groups of participants differing in age and expertise level. To this aim, young (18-25 yr) as well as late middle-aged (55-65 yr) novices and experts (precision mechanics) performed a force maintenance and a force modulation task. Results showed that whereas the amplitude of force variability did not differ across groups in the maintenance tasks, in the modulation task it was higher for late middle-aged novices than for experts and higher for both these groups than for young participants. Within both tasks and for all groups, stochastic fluctuations were lowest where the deterministic influence was smallest. However, although all groups showed similar dynamics underlying force control in the maintenance task, a group effect was found for deterministic and stochastic fluctuations in the modulation task. The latter findings imply that both components were involved in the observed group differences in the variability of force fluctuations in the modulation task. These findings suggest that between groups the general characteristics of the dynamics do not differ in either task and that force control is more affected by age than by expertise. However, expertise seems to counteract some of the age effects. NEW & NOTEWORTHY Stochastic and deterministic dynamical components contribute to force production. Dynamical signatures differ between force maintenance and cyclic force modulation tasks but hardly between age and expertise groups. Differences in both stochastic and deterministic components are associated with group differences in behavioral variability, and observed behavioral variability is more strongly task dependent than person dependent. Copyright © 2017 the American Physiological Society.

Do frailty and cognitive impairment affect dual-task cost during walking in the oldest old institutionalized patients?

PubMed

Cadore, Eduardo L; Casas-Herrero, Alvaro; Zambom-Ferraresi, Fabricio; Martínez-Ramírez, Alicia; Millor, Nora; Gómez, Marisol; Moneo, Ana B Bays; Izquierdo, Mikel

2015-12-01

The objective of this study was to investigate dual-task costs in several elderly populations, including robust oldest old, frail oldest old with MCI, frail oldest old without MCI, and frail elderly with dementia. Sixty-four elderly men and women categorized into frail without MCI (age 93.4 ± 3.2 years, n = 20), frail with MCI (age 92.4 ± 4.2 years, n = 13), robust (age 88.2 ± 4.1 years, n = 10), and patients with dementia (age 88.1 ± 5.1 years, n = 21). Five-meter gait ability and timed-up-and-go (TUG) tests with single and dual-task performance were assessed in the groups. Dual-task cost in both 5-m habitual gait velocity test and TUG test was calculated by the time differences between single and dual-task performance. The robust group exhibited better 5-m gait and TUG test performances in the single and dual-task conditions compared with the other three groups (P < 0.001), and the frail and frail + MCI groups exhibited better performances than the dementia group (P < 0.001). No significant differences were observed between the frail and frail + MCI groups. However, all groups exhibited lower gait velocities in the verbal and arithmetic task conditions, but the dual-task cost of the groups were similar. Robust individuals exhibited superior single and dual-task walking performances than the other three groups, and the frail and frail + MCI individuals exhibited performances that were superior to those of the patients with dementia. However, the dual-task costs, i.e., the changes in gait performance when elderly participants switch from a single to a dual task, were similar among all four of the investigated groups. Therefore, these results demonstrated that the magnitude of the impairment in gait pattern is independent of frailty and cognitive impairment status.

Effects of Dual-Task Management and Resistance Training on Gait Performance in Older Individuals: A Randomized Controlled Trial.

PubMed

Wollesen, Bettina; Mattes, Klaus; Schulz, Sören; Bischoff, Laura L; Seydell, L; Bell, Jeffrey W; von Duvillard, Serge P

2017-01-01

Background: Dual-task (DT) training is a well-accepted modality for fall prevention in older adults. DT training should include task-managing strategies such as task switching or task prioritization to improve gait performance under DT conditions. Methods: We conducted a randomized controlled trial to evaluate a balance and task managing training (BDT group) in gait performance compared to a single task (ST) strength and resistance training and a control group, which received no training. A total of 78 older individuals (72.0 ± 4.9 years) participated in this study. The DT group performed task managing training incorporating balance and coordination tasks while the ST group performed resistance training only. Training consisted of 12 weekly sessions, 60 min each, for 12 weeks. We assessed the effects of ST and BDT training on walking performance under ST and DT conditions in independent living elderly adults. ST and DT walking (visual verbal Stroop task) were measured utilizing a treadmill at self-selected walking speed (mean for all groups: 4.4 ± 1 km h -1 ). Specific gait variables, cognitive performance, and fear of falling were compared between all groups. > Results: Training improved gait performance for step length ( p < 0.001) and gait-line (ST: p < 0.01; DT p < 0.05) in both training groups. The BDT training group showed greater improvements in step length ( p < 0.001) and gait-line ( p < 0.01) during DT walking but did not have changes in cognitive performance. Both interventions reduced fear of falling ( p < 0.05). Conclusion: Implementation of task management strategies into balance and strength training in our population revealed a promising modality to prevent falls in older individuals. Trial registration: German register of clinical trials DRKS00012382.

Varied Practice in Laparoscopy Training: Beneficial Learning Stimulation or Cognitive Overload?

PubMed

Spruit, Edward N; Kleijweg, Luca; Band, Guido P H; Hamming, Jaap F

2016-01-01

Determining the optimal design for surgical skills training is an ongoing research endeavor. In education literature, varied practice is listed as a positive intervention to improve acquisition of knowledge and motor skills. In the current study we tested the effectiveness of a varied practice intervention during laparoscopy training. Twenty-four trainees (control group) without prior experience received a 3 weeks laparoscopic skills training utilizing four basic and one advanced training task. Twenty-eight trainees (experimental group) received the same training with a random training task schedule, more frequent task switching and inverted viewing conditions on the four basic training tasks, but not the advanced task. Results showed inferior performance of the experimental group on the four basic laparoscopy tasks during training, at the end of training and at a 2 months retention session. We assume the inverted viewing conditions have led to the deterioration of learning in the experimental group because no significant differences were found between groups on the only task that had not been practiced under inverted viewing conditions; the advanced laparoscopic task. Potential moderating effects of inter-task similarity, task complexity, and trainee characteristics are discussed.

Varied Practice in Laparoscopy Training: Beneficial Learning Stimulation or Cognitive Overload?

PubMed Central

Spruit, Edward N.; Kleijweg, Luca; Band, Guido P. H.; Hamming, Jaap F.

2016-01-01

Determining the optimal design for surgical skills training is an ongoing research endeavor. In education literature, varied practice is listed as a positive intervention to improve acquisition of knowledge and motor skills. In the current study we tested the effectiveness of a varied practice intervention during laparoscopy training. Twenty-four trainees (control group) without prior experience received a 3 weeks laparoscopic skills training utilizing four basic and one advanced training task. Twenty-eight trainees (experimental group) received the same training with a random training task schedule, more frequent task switching and inverted viewing conditions on the four basic training tasks, but not the advanced task. Results showed inferior performance of the experimental group on the four basic laparoscopy tasks during training, at the end of training and at a 2 months retention session. We assume the inverted viewing conditions have led to the deterioration of learning in the experimental group because no significant differences were found between groups on the only task that had not been practiced under inverted viewing conditions; the advanced laparoscopic task. Potential moderating effects of inter-task similarity, task complexity, and trainee characteristics are discussed. PMID:27242599

Not all choices are created equal: Task-relevant choices enhance motor learning compared to task-irrelevant choices.

PubMed

Carter, Michael J; Ste-Marie, Diane M

2017-12-01

Lewthwaite et al. (2015) reported that the learning benefits of exercising choice (i.e., their self-controlled condition) are not restricted to task-relevant features (e.g., feedback). They found that choosing one's golf ball color (Exp. 1) or choosing which of two tasks to perform at a later time plus which of two artworks to hang (Exp. 2) resulted in better retention than did being denied these same choices (i.e., yoked condition). The researchers concluded that the learning benefits derived from choice, whether irrelevant or relevant to the to-be-learned task, are predominantly motivational because choice is intrinsically rewarding and satisfies basic psychological needs. However, the absence of a group that made task-relevant choices and the lack of psychological measures significantly weakened their conclusions. Here, we investigated how task-relevant and task-irrelevant choices affect motor-skill learning. Participants practiced a spatiotemporal motor task in either a task-relevant group (choice over feedback schedule), a task-irrelevant group (choice over the color of an arm-wrap plus game selection), or a no-choice group. The results showed significantly greater learning in the task-relevant group than in both the task-irrelevant and no-choice groups, who did not differ significantly. Critically, these learning differences were not attributed to differences in perceptions of competence or autonomy, but instead to superior error-estimation abilities. These results challenge the perspective that motivational influences are the root cause of self-controlled learning advantages. Instead, the findings add to the growing evidence highlighting that the informational value gained from task-relevant choices makes a greater relative contribution to these advantages than motivational influences do.

Action planning and position sense in children with Developmental Coordination Disorder.

PubMed

Adams, Imke L J; Ferguson, Gillian D; Lust, Jessica M; Steenbergen, Bert; Smits-Engelsman, Bouwien C M

2016-04-01

The present study examined action planning and position sense in children with Developmental Coordination Disorder (DCD). Participants performed two action planning tasks, the sword task and the bar grasping task, and an active elbow matching task to examine position sense. Thirty children were included in the DCD group (aged 6-10years) and age-matched to 90 controls. The DCD group had a MABC-2 total score ⩽5th percentile, the control group a total score ⩾25th percentile. Results from the sword-task showed that children with DCD planned less for end-state comfort. On the bar grasping task no significant differences in planning for end-state comfort between the DCD and control group were found. There was also no significant difference in the position sense error between the groups. The present study shows that children with DCD plan less for end-state comfort, but that this result is task-dependent and becomes apparent when more precision is needed at the end of the task. In that respect, the sword-task appeared to be a more sensitive task to assess action planning abilities, than the bar grasping task. The action planning deficit in children with DCD cannot be explained by an impaired position sense during active movements. Copyright © 2016 Elsevier B.V. All rights reserved.

KENNEDY SPACE CENTER, FLA. - In the Columbia Debris Hangar, Shuttle Launch Director Mike Leinbach answers questions from the Stafford-Covey Return to Flight Task Group (SCTG). Chairing the task group are Richard O. Covey (fifth from left), former Space Shuttle commander, and Thomas P. Stafford, Apollo commander. Chartered by NASA Administrator Sean O’Keefe, the task group will perform an independent assessment of NASA’s implementation of the final recommendations by the Columbia Accident Investigation Board.

NASA Image and Video Library

2003-08-05

KENNEDY SPACE CENTER, FLA. - In the Columbia Debris Hangar, Shuttle Launch Director Mike Leinbach answers questions from the Stafford-Covey Return to Flight Task Group (SCTG). Chairing the task group are Richard O. Covey (fifth from left), former Space Shuttle commander, and Thomas P. Stafford, Apollo commander. Chartered by NASA Administrator Sean O’Keefe, the task group will perform an independent assessment of NASA’s implementation of the final recommendations by the Columbia Accident Investigation Board.

KENNEDY SPACE CENTER, FLA. - In the Columbia Debris Hangar, Shuttle Launch Director Mike Leinbach (left) talks to members of the Stafford-Covey Return to Flight Task Group (SCTG) about reconstruction efforts. Chairing the task group are Richard O. Covey (second from right), former Space Shuttle commander, and Thomas P. Stafford, Apollo commander. Chartered by NASA Administrator Sean O’Keefe, the task group will perform an independent assessment of NASA’s implementation of the final recommendations by the Columbia Accident Investigation Board.

NASA Image and Video Library

2003-08-05

KENNEDY SPACE CENTER, FLA. - In the Columbia Debris Hangar, Shuttle Launch Director Mike Leinbach (left) talks to members of the Stafford-Covey Return to Flight Task Group (SCTG) about reconstruction efforts. Chairing the task group are Richard O. Covey (second from right), former Space Shuttle commander, and Thomas P. Stafford, Apollo commander. Chartered by NASA Administrator Sean O’Keefe, the task group will perform an independent assessment of NASA’s implementation of the final recommendations by the Columbia Accident Investigation Board.

What makes a 'good group'? Exploring the characteristics and performance of undergraduate student groups.

PubMed

Channon, S B; Davis, R C; Goode, N T; May, S A

2017-03-01

Group work forms the foundation for much of student learning within higher education, and has many educational, social and professional benefits. This study aimed to explore the determinants of success or failure for undergraduate student teams and to define a 'good group' through considering three aspects of group success: the task, the individuals, and the team. We employed a mixed methodology, combining demographic data with qualitative observations and task and peer evaluation scores. We determined associations between group dynamic and behaviour, demographic composition, member personalities and attitudes towards one another, and task success. We also employed a cluster analysis to create a model outlining the attributes of a good small group learning team in veterinary education. This model highlights that student groups differ in measures of their effectiveness as teams, independent of their task performance. On the basis of this, we suggest that groups who achieve high marks in tasks cannot be assumed to have acquired team working skills, and therefore if these are important as a learning outcome, they must be assessed directly alongside the task output.

Can task-switching training enhance executive control functioning in children with attention deficit/-hyperactivity disorder?

PubMed

Kray, Jutta; Karbach, Julia; Haenig, Susann; Freitag, Christine

2011-01-01

The key cognitive impairments of children with attention deficit/-hyperactivity disorder (ADHD) include executive control functions such as inhibitory control, task-switching, and working memory (WM). In this training study we examined whether task-switching training leads to improvements in these functions. Twenty children with combined type ADHD and stable methylphenidate medication performed a single-task and a task-switching training in a crossover training design. The children were randomly assigned to one of two groups. One group started with the single-task training and then performed the task-switching training and the other group vice versa. The effectiveness of the task-switching training was measured as performance improvements (relative to the single-task training) on a structurally similar but new switching task and on other executive control tasks measuring inhibitory control and verbal WM as well as on fluid intelligence (reasoning). The children in both groups showed improvements in task-switching, that is, a reduction of switching costs, but not in performing the single-tasks across four training sessions. Moreover, the task-switching training lead to selective enhancements in task-switching performance, that is, the reduction of task-switching costs was found to be larger after task-switching than after single-task training. Similar selective improvements were observed for inhibitory control and verbal WM, but not for reasoning. Results of this study suggest that task-switching training is an effective cognitive intervention that helps to enhance executive control functioning in children with ADHD.

Can Task-Switching Training Enhance Executive Control Functioning in Children with Attention Deficit/-Hyperactivity Disorder?

PubMed Central

Kray, Jutta; Karbach, Julia; Haenig, Susann; Freitag, Christine

2012-01-01

The key cognitive impairments of children with attention deficit/-hyperactivity disorder (ADHD) include executive control functions such as inhibitory control, task-switching, and working memory (WM). In this training study we examined whether task-switching training leads to improvements in these functions. Twenty children with combined type ADHD and stable methylphenidate medication performed a single-task and a task-switching training in a crossover training design. The children were randomly assigned to one of two groups. One group started with the single-task training and then performed the task-switching training and the other group vice versa. The effectiveness of the task-switching training was measured as performance improvements (relative to the single-task training) on a structurally similar but new switching task and on other executive control tasks measuring inhibitory control and verbal WM as well as on fluid intelligence (reasoning). The children in both groups showed improvements in task-switching, that is, a reduction of switching costs, but not in performing the single-tasks across four training sessions. Moreover, the task-switching training lead to selective enhancements in task-switching performance, that is, the reduction of task-switching costs was found to be larger after task-switching than after single-task training. Similar selective improvements were observed for inhibitory control and verbal WM, but not for reasoning. Results of this study suggest that task-switching training is an effective cognitive intervention that helps to enhance executive control functioning in children with ADHD. PMID:22291628

Implicit and Explicit Knowledge Both Improve Dual Task Performance in a Continuous Pursuit Tracking Task.

PubMed

Ewolds, Harald E; Bröker, Laura; de Oliveira, Rita F; Raab, Markus; Künzell, Stefan

2017-01-01

The goal of this study was to investigate the effect of predictability on dual-task performance in a continuous tracking task. Participants practiced either informed (explicit group) or uninformed (implicit group) about a repeated segment in the curves they had to track. In Experiment 1 participants practices the tracking task only, dual-task performance was assessed after by combining the tracking task with an auditory reaction time task. Results showed both groups learned equally well and tracking performance on a predictable segment in the dual-task condition was better than on random segments. However, reaction times did not benefit from a predictable tracking segment. To investigate the effect of learning under dual-task situation participants in Experiment 2 practiced the tracking task while simultaneously performing the auditory reaction time task. No learning of the repeated segment could be demonstrated for either group during the training blocks, in contrast to the test-block and retention test, where participants performed better on the repeated segment in both dual-task and single-task conditions. Only the explicit group improved from test-block to retention test. As in Experiment 1, reaction times while tracking a predictable segment were no better than reaction times while tracking a random segment. We concluded that predictability has a positive effect only on the predictable task itself possibly because of a task-shielding mechanism. For dual-task training there seems to be an initial negative effect of explicit instructions, possibly because of fatigue, but the advantage of explicit instructions was demonstrated in a retention test. This might be due to the explicit memory system informing or aiding the implicit memory system.

Implicit and Explicit Knowledge Both Improve Dual Task Performance in a Continuous Pursuit Tracking Task

PubMed Central

Ewolds, Harald E.; Bröker, Laura; de Oliveira, Rita F.; Raab, Markus; Künzell, Stefan

2017-01-01

The goal of this study was to investigate the effect of predictability on dual-task performance in a continuous tracking task. Participants practiced either informed (explicit group) or uninformed (implicit group) about a repeated segment in the curves they had to track. In Experiment 1 participants practices the tracking task only, dual-task performance was assessed after by combining the tracking task with an auditory reaction time task. Results showed both groups learned equally well and tracking performance on a predictable segment in the dual-task condition was better than on random segments. However, reaction times did not benefit from a predictable tracking segment. To investigate the effect of learning under dual-task situation participants in Experiment 2 practiced the tracking task while simultaneously performing the auditory reaction time task. No learning of the repeated segment could be demonstrated for either group during the training blocks, in contrast to the test-block and retention test, where participants performed better on the repeated segment in both dual-task and single-task conditions. Only the explicit group improved from test-block to retention test. As in Experiment 1, reaction times while tracking a predictable segment were no better than reaction times while tracking a random segment. We concluded that predictability has a positive effect only on the predictable task itself possibly because of a task-shielding mechanism. For dual-task training there seems to be an initial negative effect of explicit instructions, possibly because of fatigue, but the advantage of explicit instructions was demonstrated in a retention test. This might be due to the explicit memory system informing or aiding the implicit memory system. PMID:29312083

Effects of Single Compared to Dual Task Practice on Learning a Dynamic Balance Task in Young Adults

PubMed Central

Kiss, Rainer; Brueckner, Dennis; Muehlbauer, Thomas

2018-01-01

Background: In everyday life, people engage in situations involving the concurrent processing of motor (balance) and cognitive tasks (i.e., “dual task situations”) that result in performance declines in at least one of the given tasks. The concurrent practice of both the motor and cognitive task may counteract these performance decrements. The purpose of this study was to examine the effects of single task (ST) compared to dual task (DT) practice on learning a dynamic balance task. Methods: Forty-eight young adults were randomly assigned to either a ST (i.e., motor or cognitive task training only) or a DT (i.e., motor-cognitive training) practice condition. The motor task required participants to stand on a platform and keeping the platform as close to horizontal as possible. In the cognitive task, participants were asked to recite serial subtractions of three. For 2 days, participants of the ST groups practiced the motor or cognitive task only, while the participants of the DT group concurrently performed both. Root-mean-square error (RMSE) for the motor and total number of correct calculations for the cognitive task were computed. Results: During practice, all groups improved their respective balance and/or cognitive task performance. With regard to the assessment of learning on day 3, we found significantly smaller RMSE values for the ST motor (d = 1.31) and the DT motor-cognitive (d = 0.76) practice group compared to the ST cognitive practice group but not between the ST motor and the DT motor-cognitive practice group under DT test condition. Further, we detected significantly larger total numbers of correct calculations under DT test condition for the ST cognitive (d = 2.19) and the DT motor-cognitive (d = 1.55) practice group compared to the ST motor practice group but not between the ST cognitive and the DT motor-cognitive practice group. Conclusion: We conclude that ST practice resulted in an effective modulation of the trained domain (i.e., motor or cognitive) while only DT practice resulted in an effective modulation of both domains (i.e., motor and cognitive). Thus, particularly DT practice frees up central resources that were used for an effective modulation of motor and cognitive processing mechanisms. PMID:29593614

Cognitive and motor dual task gait training improve dual task gait performance after stroke - A randomized controlled pilot trial.

PubMed

Liu, Yan-Ci; Yang, Yea-Ru; Tsai, Yun-An; Wang, Ray-Yau

2017-06-22

This study investigated effects of cognitive and motor dual task gait training on dual task gait performance in stroke. Participants (n = 28) were randomly assigned to cognitive dual task gait training (CDTT), motor dual task gait training (MDTT), or conventional physical therapy (CPT) group. Participants in CDTT or MDTT group practiced the cognitive or motor tasks respectively during walking. Participants in CPT group received strengthening, balance, and gait training. The intervention was 30 min/session, 3 sessions/week for 4 weeks. Three test conditions to evaluate the training effects were single walking, walking while performing cognitive task (serial subtraction), and walking while performing motor task (tray-carrying). Parameters included gait speed, dual task cost of gait speed (DTC-speed), cadence, stride time, and stride length. After CDTT, cognitive-motor dual task gait performance (stride length and DTC-speed) was improved (p = 0.021; p = 0.015). After MDTT, motor dual task gait performance (gait speed, stride length, and DTC-speed) was improved (p = 0.008; p = 0.008; p = 0.008 respectively). It seems that CDTT improved cognitive dual task gait performance and MDTT improved motor dual task gait performance although such improvements did not reach significant group difference. Therefore, different types of dual task gait training can be adopted to enhance different dual task gait performance in stroke.

Effects of virtual reality-based training and task-oriented training on balance performance in stroke patients.

PubMed

Lee, Hyung Young; Kim, You Lim; Lee, Suk Min

2015-06-01

[Purpose] This study aimed to investigate the clinical effects of virtual reality-based training and task-oriented training on balance performance in stroke patients. [Subjects and Methods] The subjects were randomly allocated to 2 groups: virtual reality-based training group (n = 12) and task-oriented training group (n = 12). The patients in the virtual reality-based training group used the Nintendo Wii Fit Plus, which provided visual and auditory feedback as well as the movements that enabled shifting of weight to the right and left sides, for 30 min/day, 3 times/week for 6 weeks. The patients in the task-oriented training group practiced additional task-oriented programs for 30 min/day, 3 times/week for 6 weeks. Patients in both groups also underwent conventional physical therapy for 60 min/day, 5 times/week for 6 weeks. [Results] Balance and functional reach test outcomes were examined in both groups. The results showed that the static balance and functional reach test outcomes were significantly higher in the virtual reality-based training group than in the task-oriented training group. [Conclusion] This study suggested that virtual reality-based training might be a more feasible and suitable therapeutic intervention for dynamic balance in stroke patients compared to task-oriented training.

Effects of virtual reality-based training and task-oriented training on balance performance in stroke patients

PubMed Central

Lee, Hyung Young; Kim, You Lim; Lee, Suk Min

2015-01-01

[Purpose] This study aimed to investigate the clinical effects of virtual reality-based training and task-oriented training on balance performance in stroke patients. [Subjects and Methods] The subjects were randomly allocated to 2 groups: virtual reality-based training group (n = 12) and task-oriented training group (n = 12). The patients in the virtual reality-based training group used the Nintendo Wii Fit Plus, which provided visual and auditory feedback as well as the movements that enabled shifting of weight to the right and left sides, for 30 min/day, 3 times/week for 6 weeks. The patients in the task-oriented training group practiced additional task-oriented programs for 30 min/day, 3 times/week for 6 weeks. Patients in both groups also underwent conventional physical therapy for 60 min/day, 5 times/week for 6 weeks. [Results] Balance and functional reach test outcomes were examined in both groups. The results showed that the static balance and functional reach test outcomes were significantly higher in the virtual reality-based training group than in the task-oriented training group. [Conclusion] This study suggested that virtual reality-based training might be a more feasible and suitable therapeutic intervention for dynamic balance in stroke patients compared to task-oriented training. PMID:26180341

WHY DOES OLDER ADULTS' BALANCE BECOME LESS STABLE WHEN WALKING AND PERFORMING A SECONDARY TASK? EXAMINATION OF ATTENTIONAL SWITCHING ABILITIES

PubMed Central

Hawkes, Teresa D; Siu, Ka-Chun; Silsupadol, Patima; Woollacott, Marjorie H.

2011-01-01

Previous research using dual-task paradigms indicates balance-impaired older adults (BIOA) are less able to flexibly shift attentional focus between a cognitive and motor task than healthy older adults (HOA). Shifting attention is a component of executive function. Task switch tests assess executive attention function. This multivariate study asked if BIOAs demonstrate greater task switching deficits than HOAs. A group of 39 HOA (65–80 yrs) and BIOA (65–87 yrs) subjects performed a visuo-spatial task switch. A sub-group of subjects performed a dual-task obstacle avoidance paradigm. All participants completed the Berg Balance Scale (BBS) and Timed Up and Go (TUG). We assessed differences by group for: 1) visuo-spatial task switch reaction times (switch/no-switch), and performance on the BBS and TUG. Our balance groups differed significantly on BBS score (p < .001) and switch reaction time (p = .032), but not the TUG. This confirmed our hypothesis that neuromuscular and executive attention function differs between these two groups. For our BIOA sub-group, gait velocity correlated negatively with performance on the switch condition (p=.036). This suggests that BIOA efficiency of attentional allocation in dual task settings should be further explored. PMID:21964051

Decision-making under risk conditions is susceptible to interference by a secondary executive task.

PubMed

Starcke, Katrin; Pawlikowski, Mirko; Wolf, Oliver T; Altstötter-Gleich, Christine; Brand, Matthias

2011-05-01

Recent research suggests two ways of making decisions: an intuitive and an analytical one. The current study examines whether a secondary executive task interferes with advantageous decision-making in the Game of Dice Task (GDT), a decision-making task with explicit and stable rules that taps executive functioning. One group of participants performed the original GDT solely, two groups performed either the GDT and a 1-back or a 2-back working memory task as a secondary task simultaneously. Results show that the group which performed the GDT and the secondary task with high executive load (2-back) decided less advantageously than the group which did not perform a secondary executive task. These findings give further evidence for the view that decision-making under risky conditions taps into the rational-analytical system which acts in a serial and not parallel way as performance on the GDT is disturbed by a parallel task that also requires executive resources.

The Use of Consciousness-Raising Tasks in Learning and Teaching of Subject-Verb Agreement

ERIC Educational Resources Information Center

Idek, Sirhajwan; Fong, Lee Lai; Sidhu, Gurnam Kaur

2013-01-01

This study investigates the use of two types of Consciousness-Raising (CR) tasks in learning Subject-Verb Agreement (SVA). The sample consisted of 28 Form 2 students who were divided into two groups. Group 1 was assigned with Grammaticality Judgment (GJ) tasks and Group 2 received Sentence Production (SP) tasks for eight weeks. Learners were given…

An Agent-Based Simulation for Investigating the Impact of Stereotypes on Task-Oriented Group Formation

NASA Astrophysics Data System (ADS)

Maghami, Mahsa; Sukthankar, Gita

In this paper, we introduce an agent-based simulation for investigating the impact of social factors on the formation and evolution of task-oriented groups. Task-oriented groups are created explicitly to perform a task, and all members derive benefits from task completion. However, even in cases when all group members act in a way that is locally optimal for task completion, social forces that have mild effects on choice of associates can have a measurable impact on task completion performance. In this paper, we show how our simulation can be used to model the impact of stereotypes on group formation. In our simulation, stereotypes are based on observable features, learned from prior experience, and only affect an agent's link formation preferences. Even without assuming stereotypes affect the agents' willingness or ability to complete tasks, the long-term modifications that stereotypes have on the agents' social network impair the agents' ability to form groups with sufficient diversity of skills, as compared to agents who form links randomly. An interesting finding is that this effect holds even in cases where stereotype preference and skill existence are completely uncorrelated.

Task Performance in Small Group Settings: The Role of Group Members' Self-Efficacy And Collective Efficacy and Group's Characteristics

ERIC Educational Resources Information Center

Khong, Jerrine Z. N.; Liem, Gregory Arief D.; Klassen, Robert M.

2017-01-01

The present study extends the literature by investigating the relative salience of self- and collective efficacy in predicting group performance among early adolescents in Indonesia. A total of 435 early adolescents (mean age 11.70 years, 53% female) were randomly assigned to groups of three to four and completed three group tasks (task 1:…

Dynamic Task Performance, Cohesion, and Communications in Human Groups.

PubMed

Giraldo, Luis Felipe; Passino, Kevin M

2016-10-01

In the study of the behavior of human groups, it has been observed that there is a strong interaction between the cohesiveness of the group, its performance when the group has to solve a task, and the patterns of communication between the members of the group. Developing mathematical and computational tools for the analysis and design of task-solving groups that are not only cohesive but also perform well is of importance in social sciences, organizational management, and engineering. In this paper, we model a human group as a dynamical system whose behavior is driven by a task optimization process and the interaction between subsystems that represent the members of the group interconnected according to a given communication network. These interactions are described as attractions and repulsions among members. We show that the dynamics characterized by the proposed mathematical model are qualitatively consistent with those observed in real-human groups, where the key aspect is that the attraction patterns in the group and the commitment to solve the task are not static but change over time. Through a theoretical analysis of the system we provide conditions on the parameters that allow the group to have cohesive behaviors, and Monte Carlo simulations are used to study group dynamics for different sets of parameters, communication topologies, and tasks to solve.

[Features of dual--postural and calculation--task performance in patients with consequences of traumatic brain injury].

PubMed

Zharikova, A V; Zhavoronkova, L A; Maksakova, O A; Kuptsova, S V

2012-01-01

Dual tasks with voluntary postural control and calculation have been done by 14 patients (25.7 +/- 4.7 yo.) after traumatic brain injury and 40 healthy volunteers (29.8 +/- 2.5 y.o.). Complex clinical (MMSE, FIM, MPAI-3 and Berg scales) and stabilographic evaluation has been performed. According to clinical evaluation 8 patients were included into group 1 with less severe functional deficit and 6 patients formed group 2 with more severe deficit. Parameters of motor and especially cognitive sub-tasks in patients were lower than in healthy subjects in both separate and dual tasks. In group 2 these parameters were lower than in group 1. Certain types of dual task where the quality of sub-tasks, especially of the motor-one increased in healthy subjects and patients of the first group were revealed. The complex of stabilographic parameters which could be used for estimation of quality of sub-tasks performance has been revealed. Dual tasks could be an additional method of evaluation of patients' adaptive possibilities and certain type of dual task could become a promising approach to recovery at late period of rehabilitation.

Poster - 19: Investigation of Electron Reference Dosimetry Based on Optimal Chamber Shift

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhan, Lixin; Jiang, Runqing; Liu, Baochang

An addendum/revision to AAPM TG-51 electron reference dosimetry is highly expected to meet the clinical requirement with the increasing usage of new ion chambers not covered in TG-51. A recent study, Med. Phys. 41, 111701, proposed a new fitting equation for the beam quality conversion factor k’{sub Q} to a wide spectrum of chambers. In the study, an optimal Effective Point of Measurement (EPOM) from Monte Carlo calculations was recommended and the fitting parameters to k’{sub Q} was based on it. We investigated the absolute dose obtained based on the optimal EPOM method and the original TG-51 method with k’{submore » R50} determined differently. The results showed that using the Markus curve is a better choice than the well-guarded chamber fitting for an IBA PPC-05 parallel plate chamber if we need to strictly follow the AAPM TG-51 protocol. We also examined the usage of the new fitting equation with measurement performed at the physical EPOM, instead of the optimal EPOM. The former is more readily determined and more practical in clinics. Our study indicated that the k’{sub Q} fitting based on the optimal EPOM can be used to measurement at the physical EPOM with no significant clinical impact. The inclusion of Farmer chamber gradient correction P{sub gr} in k’{sub Q}, as in the mentioned study, asks for the precise positioning of chamber center at dref. It is not recommended in clinics to avoid over-correction for low electron energies, especially for an institute having matching Linacs implemented.« less

Shifting of attentional set is inadequate in severe burnout: Evidence from an event-related potential study.

PubMed

Sokka, Laura; Leinikka, Marianne; Korpela, Jussi; Henelius, Andreas; Lukander, Jani; Pakarinen, Satu; Alho, Kimmo; Huotilainen, Minna

2017-02-01

Individuals with prolonged occupational stress often report difficulties in concentration. Work tasks often require the ability to switch back and forth between different contexts. Here, we studied the association between job burnout and task switching by recording event-related potentials (ERPs) time-locked to stimulus onset during a task with simultaneous cue-target presentation and unpredictable switches in the task. Participants were currently working people with severe, mild, or no burnout symptoms. In all groups, task performance was substantially slower immediately after task switch than during task repetition. However, the error rates were higher in the severe burnout group than in the mild burnout and control groups. Electrophysiological data revealed an increased parietal P3 response for the switch trials relative to repetition trials. Notably, the response was smaller in amplitude in the severe burnout group than in the other groups. The results suggest that severe burnout is associated with inadequate processing when rapid shifting of attention between tasks is required resulting in less accurate performance. Copyright © 2016 Elsevier B.V. All rights reserved.

Comprehensive quality assurance phantom for cardiovascular imaging systems

NASA Astrophysics Data System (ADS)

Lin, Pei-Jan P.

1998-07-01

With the advent of high heat loading capacity x-ray tubes, high frequency inverter type generators, and the use of spectral shaping filters, the automatic brightness/exposure control (ABC) circuit logic employed in the new generation of angiographic imaging equipment has been significantly reprogrammed. These new angiographic imaging systems are designed to take advantage of the power train capabilities to yield higher contrast images while maintaining, or lower, the patient exposure. Since the emphasis of the imaging system design has been significantly altered, the system performance parameters one is interested and the phantoms employed for the quality assurance must also change in order to properly evaluate the imaging capability of the cardiovascular imaging systems. A quality assurance (QA) phantom has been under development in this institution and was submitted to various interested organizations such as American Association of Physicists in Medicine (AAPM), Society for Cardiac Angiography & Interventions (SCA&I), and National Electrical Manufacturers Association (NEMA) for their review and input. At the same time, in an effort to establish a unified standard phantom design for the cardiac catheterization laboratories (CCL), SCA&I and NEMA have formed a joint work group in early 1997 to develop a suitable phantom. The initial QA phantom design has since been accepted to serve as the base phantom by the SCA&I- NEMA Joint Work Group (JWG) from which a comprehensive QA Phantom is being developed.

Positive is usually good, negative is not always bad: The effects of group affect on social integration and task performance.

PubMed

Knight, Andrew P; Eisenkraft, Noah

2015-07-01

Grounded in a social functional perspective, this article examines the conditions under which group affect influences group functioning. Using meta-analysis, the authors leverage heterogeneity across 39 independent studies of 2,799 groups to understand how contextual factors-group affect source (exogenous or endogenous to the group) and group life span (one-shot or ongoing)-moderate the influence of shared feelings on social integration and task performance. As predicted, results indicate that group positive affect has consistent positive effects on social integration and task performance regardless of contextual idiosyncrasies. The effects of group negative affect, on the other hand, are context-dependent. Shared negative feelings promote social integration and task performance when stemming from an exogenous source or experienced in a 1-shot group, but undermine social integration and task performance when stemming from an endogenous source or experienced in an ongoing group. The authors discuss implications of their findings and highlight directions for future theory and research on group affect. (c) 2015 APA, all rights reserved).

Multi-task learning with group information for human action recognition

NASA Astrophysics Data System (ADS)

Qian, Li; Wu, Song; Pu, Nan; Xu, Shulin; Xiao, Guoqiang

2018-04-01

Human action recognition is an important and challenging task in computer vision research, due to the variations in human motion performance, interpersonal differences and recording settings. In this paper, we propose a novel multi-task learning framework with group information (MTL-GI) for accurate and efficient human action recognition. Specifically, we firstly obtain group information through calculating the mutual information according to the latent relationship between Gaussian components and action categories, and clustering similar action categories into the same group by affinity propagation clustering. Additionally, in order to explore the relationships of related tasks, we incorporate group information into multi-task learning. Experimental results evaluated on two popular benchmarks (UCF50 and HMDB51 datasets) demonstrate the superiority of our proposed MTL-GI framework.

Brain dynamics of post-task resting state are influenced by expertise: Insights from baseball players.

PubMed

Muraskin, Jordan; Dodhia, Sonam; Lieberman, Gregory; Garcia, Javier O; Verstynen, Timothy; Vettel, Jean M; Sherwin, Jason; Sajda, Paul

2016-12-01

Post-task resting state dynamics can be viewed as a task-driven state where behavioral performance is improved through endogenous, non-explicit learning. Tasks that have intrinsic value for individuals are hypothesized to produce post-task resting state dynamics that promote learning. We measured simultaneous fMRI/EEG and DTI in Division-1 collegiate baseball players and compared to a group of controls, examining differences in both functional and structural connectivity. Participants performed a surrogate baseball pitch Go/No-Go task before a resting state scan, and we compared post-task resting state connectivity using a seed-based analysis from the supplementary motor area (SMA), an area whose activity discriminated players and controls in our previous results using this task. Although both groups were equally trained on the task, the experts showed differential activity in their post-task resting state consistent with motor learning. Specifically, we found (1) differences in bilateral SMA-L Insula functional connectivity between experts and controls that may reflect group differences in motor learning, (2) differences in BOLD-alpha oscillation correlations between groups suggests variability in modulatory attention in the post-task state, and (3) group differences between BOLD-beta oscillations that may indicate cognitive processing of motor inhibition. Structural connectivity analysis identified group differences in portions of the functionally derived network, suggesting that functional differences may also partially arise from variability in the underlying white matter pathways. Generally, we find that brain dynamics in the post-task resting state differ as a function of subject expertise and potentially result from differences in both functional and structural connectivity. Hum Brain Mapp 37:4454-4471, 2016. © 2016 The Authors Human Brain Mapping Published by Wiley Periodicals, Inc. © 2016 The Authors Human Brain Mapping Published by Wiley Periodicals, Inc.

Hemispheric processing of vocal emblem sounds.

PubMed

Neumann-Werth, Yael; Levy, Erika S; Obler, Loraine K

2013-01-01

Vocal emblems, such as shh and brr, are speech sounds that have linguistic and nonlinguistic features; thus, it is unclear how they are processed in the brain. Five adult dextral individuals with left-brain damage and moderate-severe Wernicke's aphasia, five adult dextral individuals with right-brain damage, and five Controls participated in two tasks: (1) matching vocal emblems to photographs ('picture task') and (2) matching vocal emblems to verbal translations ('phrase task'). Cross-group statistical analyses on items on which the Controls performed at ceiling revealed lower accuracy by the group with left-brain damage (than by Controls) on both tasks, and lower accuracy by the group with right-brain damage (than by Controls) on the picture task. Additionally, the group with left-brain damage performed significantly less accurately than the group with right-brain damage on the phrase task only. Findings suggest that comprehension of vocal emblems recruits more left- than right-hemisphere processing.

Perceptual and conceptual information processing in schizophrenia and depression.

PubMed

Dreben, E K; Fryer, J H; McNair, D M

1995-04-01

Schizophrenic patients (n = 20), depressive patients (n = 20), and normal adults (n = 20) were compared on global vs local analyses of perceptual information using tachistoscopic tasks and on top-down vs bottom-up conceptual processing using card-sort tasks. The schizophrenic group performed more poorly on tasks requiring either global analyses (counting lines when distracting circles were present) or top-down conceptual processing (rule learning) than they did on tasks requiring local analyses (counting heterogeneous lines) or bottom-up processing (attribute identification). The schizophrenic group appeared not to use conceptually guided processing. Normal adults showed the reverse pattern. The depressive group performed similarly to the schizophrenic group on perceptual tasks but closer to the normal group on conceptual tasks, thereby appearing to be less dependent on a particular information-processing strategy. These deficits in organizational strategy may be related to the use of available processing resources as well as the allocation of attention.

KENNEDY SPACE CENTER, FLA. - The Stafford-Covey Return to Flight Task Group (SCTG) inspects debris in the Columbia Debris Hangar. At right is the model of the left wing that has been used during recovery operations. Chairing the task group are Richard O. Covey, former Space Shuttle commander, and Thomas P. Stafford (third from right, foreground), Apollo commander. Chartered by NASA Administrator Sean O’Keefe, the task group will perform an independent assessment of NASA’s implementation of the final recommendations by the Columbia Accident Investigation Board.

NASA Image and Video Library

2003-08-05

KENNEDY SPACE CENTER, FLA. - The Stafford-Covey Return to Flight Task Group (SCTG) inspects debris in the Columbia Debris Hangar. At right is the model of the left wing that has been used during recovery operations. Chairing the task group are Richard O. Covey, former Space Shuttle commander, and Thomas P. Stafford (third from right, foreground), Apollo commander. Chartered by NASA Administrator Sean O’Keefe, the task group will perform an independent assessment of NASA’s implementation of the final recommendations by the Columbia Accident Investigation Board.

Effect of Tai Chi Training on Dual-Tasking Performance That Involves Stepping Down among Stroke Survivors: A Pilot Study.

PubMed

Chan, Wing-Nga; Tsang, William Wai-Nam

2017-01-01

Descending stairs demands attention and neuromuscular control, especially with dual-tasking. Studies have demonstrated that stroke often degrades a survivor's ability to descend stairs. Tai Chi has been shown to improve dual-tasking performance of healthy older adults, but no such study has been conducted in stroke survivors. This study investigated the effect of Tai Chi training on dual-tasking performance that involved stepping down and compared it with that of conventional exercise among stroke survivors. Subjects were randomized into Tai Chi ( n = 9), conventional exercise ( n = 8), and control ( n = 9) groups. Those in the former two groups received 12-week training. Assessments included auditory Stroop test, stepping down test, and dual-tasking test involving both simultaneously. They were evaluated before training (time-1), after training (time-2), and one month after training (time-3). Tai Chi group showed significant improvement in the auditory Stroop test from time-1 to time-3 and the performance was significantly better than that of the conventional exercise group in time-3. No significant effect was found in the stepping down task or dual-tasking in the control group. These results suggest a beneficial effect of Tai Chi training on cognition among stroke survivors without compromising physical task performance in dual-tasking. The effect was better than the conventional exercise group. Nevertheless, further research with a larger sample is warranted.

Adaptive group coordination and role differentiation.

PubMed

Roberts, Michael E; Goldstone, Robert L

2011-01-01

Many real world situations (potluck dinners, academic departments, sports teams, corporate divisions, committees, seminar classes, etc.) involve actors adjusting their contributions in order to achieve a mutually satisfactory group goal, a win-win result. However, the majority of human group research has involved situations where groups perform poorly because task constraints promote either individual maximization behavior or diffusion of responsibility, and even successful tasks generally involve the propagation of one correct solution through a group. Here we introduce a group task that requires complementary actions among participants in order to reach a shared goal. Without communication, group members submit numbers in an attempt to collectively sum to a randomly selected target number. After receiving group feedback, members adjust their submitted numbers until the target number is reached. For all groups, performance improves with task experience, and group reactivity decreases over rounds. Our empirical results provide evidence for adaptive coordination in human groups, and as the coordination costs increase with group size, large groups adapt through spontaneous role differentiation and self-consistency among members. We suggest several agent-based models with different rules for agent reactions, and we show that the empirical results are best fit by a flexible, adaptive agent strategy in which agents decrease their reactions when the group feedback changes. The task offers a simple experimental platform for studying the general problem of group coordination while maximizing group returns, and we distinguish the task from several games in behavioral game theory.

Generalization of Auditory Sensory and Cognitive Learning in Typically Developing Children.

PubMed

Murphy, Cristina F B; Moore, David R; Schochat, Eliane

2015-01-01

Despite the well-established involvement of both sensory ("bottom-up") and cognitive ("top-down") processes in literacy, the extent to which auditory or cognitive (memory or attention) learning transfers to phonological and reading skills remains unclear. Most research has demonstrated learning of the trained task or even learning transfer to a closely related task. However, few studies have reported "far-transfer" to a different domain, such as the improvement of phonological and reading skills following auditory or cognitive training. This study assessed the effectiveness of auditory, memory or attention training on far-transfer measures involving phonological and reading skills in typically developing children. Mid-transfer was also assessed through untrained auditory, attention and memory tasks. Sixty 5- to 8-year-old children with normal hearing were quasi-randomly assigned to one of five training groups: attention group (AG), memory group (MG), auditory sensory group (SG), placebo group (PG; drawing, painting), and a control, untrained group (CG). Compliance, mid-transfer and far-transfer measures were evaluated before and after training. All trained groups received 12 x 45-min training sessions over 12 weeks. The CG did not receive any intervention. All trained groups, especially older children, exhibited significant learning of the trained task. On pre- to post-training measures (test-retest), most groups exhibited improvements on most tasks. There was significant mid-transfer for a visual digit span task, with highest span in the MG, relative to other groups. These results show that both sensory and cognitive (memory or attention) training can lead to learning in the trained task and to mid-transfer learning on a task (visual digit span) within the same domain as the trained tasks. However, learning did not transfer to measures of language (reading and phonological awareness), as the PG and CG improved as much as the other trained groups. Further research is required to investigate the effects of various stimuli and lengths of training on the generalization of sensory and cognitive learning to literacy skills.

Node, Node-Link, and Node-Link-Group Diagrams: An Evaluation.

PubMed

Saket, Bahador; Simonetto, Paolo; Kobourov, Stephen; Börner, Katy

2014-12-01

Effectively showing the relationships between objects in a dataset is one of the main tasks in information visualization. Typically there is a well-defined notion of distance between pairs of objects, and traditional approaches such as principal component analysis or multi-dimensional scaling are used to place the objects as points in 2D space, so that similar objects are close to each other. In another typical setting, the dataset is visualized as a network graph, where related nodes are connected by links. More recently, datasets are also visualized as maps, where in addition to nodes and links, there is an explicit representation of groups and clusters. We consider these three Techniques, characterized by a progressive increase of the amount of encoded information: node diagrams, node-link diagrams and node-link-group diagrams. We assess these three types of diagrams with a controlled experiment that covers nine different tasks falling broadly in three categories: node-based tasks, network-based tasks and group-based tasks. Our findings indicate that adding links, or links and group representations, does not negatively impact performance (time and accuracy) of node-based tasks. Similarly, adding group representations does not negatively impact the performance of network-based tasks. Node-link-group diagrams outperform the others on group-based tasks. These conclusions contradict results in other studies, in similar but subtly different settings. Taken together, however, such results can have significant implications for the design of standard and domain snecific visualizations tools.

Performance improvements from imagery: evidence that internal visual imagery is superior to external visual imagery for slalom performance

PubMed Central

Callow, Nichola; Roberts, Ross; Hardy, Lew; Jiang, Dan; Edwards, Martin Gareth

2013-01-01

We report three experiments investigating the hypothesis that use of internal visual imagery (IVI) would be superior to external visual imagery (EVI) for the performance of different slalom-based motor tasks. In Experiment 1, three groups of participants (IVI, EVI, and a control group) performed a driving-simulation slalom task. The IVI group achieved significantly quicker lap times than EVI and the control group. In Experiment 2, participants performed a downhill running slalom task under both IVI and EVI conditions. Performance was again quickest in the IVI compared to EVI condition, with no differences in accuracy. Experiment 3 used the same group design as Experiment 1, but with participants performing a downhill ski-slalom task. Results revealed the IVI group to be significantly more accurate than the control group, with no significant differences in time taken to complete the task. These results support the beneficial effects of IVI for slalom-based tasks, and significantly advances our knowledge related to the differential effects of visual imagery perspectives on motor performance. PMID:24155710

Effects of task-irrelevant grouping on visual selection in partial report.

PubMed

Lunau, Rasmus; Habekost, Thomas

2017-07-01

Perceptual grouping modulates performance in attention tasks such as partial report and change detection. Specifically, grouping of search items according to a task-relevant feature improves the efficiency of visual selection. However, the role of task-irrelevant feature grouping is not clearly understood. In the present study, we investigated whether grouping of targets by a task-irrelevant feature influences performance in a partial-report task. In this task, participants must report as many target letters as possible from a briefly presented circular display. The crucial manipulation concerned the color of the elements in these trials. In the sorted-color condition, the color of the display elements was arranged according to the selection criterion, and in the unsorted-color condition, colors were randomly assigned. The distractor cost was inferred by subtracting performance in partial-report trials from performance in a control condition that had no distractors in the display. Across five experiments, we manipulated trial order, selection criterion, and exposure duration, and found that attentional selectivity was improved in sorted-color trials when the exposure duration was 200 ms and the selection criterion was luminance. This effect was accompanied by impaired selectivity in unsorted-color trials. Overall, the results suggest that the benefit of task-irrelevant color grouping of targets is contingent on the processing locus of the selection criterion.

Limited Effects of Set Shifting Training in Healthy Older Adults

PubMed Central

Grönholm-Nyman, Petra; Soveri, Anna; Rinne, Juha O.; Ek, Emilia; Nyholm, Alexandra; Stigsdotter Neely, Anna; Laine, Matti

2017-01-01

Our ability to flexibly shift between tasks or task sets declines in older age. As this decline may have adverse effects on everyday life of elderly people, it is of interest to study whether set shifting ability can be trained, and if training effects generalize to other cognitive tasks. Here, we report a randomized controlled trial where healthy older adults trained set shifting with three different set shifting tasks. The training group (n = 17) performed adaptive set shifting training for 5 weeks with three training sessions a week (45 min/session), while the active control group (n = 16) played three different computer games for the same period. Both groups underwent extensive pre- and post-testing and a 1-year follow-up. Compared to the controls, the training group showed significant improvements on the trained tasks. Evidence for near transfer in the training group was very limited, as it was seen only on overall accuracy on an untrained computerized set shifting task. No far transfer to other cognitive functions was observed. One year later, the training group was still better on the trained tasks but the single near transfer effect had vanished. The results suggest that computerized set shifting training in the elderly shows long-lasting effects on the trained tasks but very little benefit in terms of generalization. PMID:28386226

Control system of the inspection robots group applying auctions and multi-criteria analysis for task allocation

NASA Astrophysics Data System (ADS)

Panfil, Wawrzyniec; Moczulski, Wojciech

2017-10-01

In the paper presented is a control system of a mobile robots group intended for carrying out inspection missions. The main research problem was to define such a control system in order to facilitate a cooperation of the robots resulting in realization of the committed inspection tasks. Many of the well-known control systems use auctions for tasks allocation, where a subject of an auction is a task to be allocated. It seems that in the case of missions characterized by much larger number of tasks than number of robots it will be better if robots (instead of tasks) are subjects of auctions. The second identified problem concerns the one-sided robot-to-task fitness evaluation. Simultaneous assessment of the robot-to-task fitness and task attractiveness for robot should affect positively for the overall effectiveness of the multi-robot system performance. The elaborated system allows to assign tasks to robots using various methods for evaluation of fitness between robots and tasks, and using some tasks allocation methods. There is proposed the method for multi-criteria analysis, which is composed of two assessments, i.e. robot's concurrency position for task among other robots and task's attractiveness for robot among other tasks. Furthermore, there are proposed methods for tasks allocation applying the mentioned multi-criteria analysis method. The verification of both the elaborated system and the proposed tasks' allocation methods was carried out with the help of simulated experiments. The object under test was a group of inspection mobile robots being a virtual counterpart of the real mobile-robot group.

Friends With Performance Benefits: A Meta-Analysis on the Relationship Between Friendship and Group Performance.

PubMed

Chung, Seunghoo; Lount, Robert B; Park, Hee Man; Park, Ernest S

2018-01-01

The current article examines if, and under which conditions, there exists a positive relationship between working with friends and group performance. To do so, using data from 1,016 groups obtained from 26 studies, we meta-analyzed comparisons of the performance of friendship groups versus acquaintance groups. Results show that friendship has a significant positive effect on group task performance (Cohen's d = 0.31). Furthermore, this relationship was moderated by group size (i.e., the positive effect of friendship on performance increased with group size) and task focus (i.e., friendship groups performed better than acquaintance groups on tasks requiring a high quantity of output, whereas there was no performance benefit on tasks requiring a single or high-quality output). These results help to reconcile mixed findings and illustrate when friendship groups are more likely to perform better than acquaintance groups.

[Job performance in work organizations: the effects of management by group goals and job interdependence].

PubMed

Ikeda, Hiroshi; Furukawa, Hisataka

2015-04-01

cThis study examined the interactive effect of management by group goals and job interdependence on employee's activities in terms of task and contextual performance. A survey was conducted among 140 Japanese employees. Results indicated that management by group goals was related only to contextual performance. Job interdependence, however, had a direct effect on both task and contextual performance. Moreover, moderated regression analyses revealed that for work groups requiring higher interdependence among employees, management by group goals had a positive relation to contextual performance but not to task performance. When interdependence was not necessarily required, however, management by group goals had no relation to contextual performance and even negatively impacted task performance, respectively. These results show that management by group goals affects task and contextual performance, and that this effect is moderated by job interdependence. This provides a theoretical extension as well as a practical application to the setting and management of group goals.

Perception Measurement in Clinical Trials of Schizophrenia: Promising Paradigms From CNTRICS

PubMed Central

Green, Michael F.; Butler, Pamela D.; Chen, Yue; Geyer, Mark A.; Silverstein, Steven; Wynn, Jonathan K.; Yoon, Jong H.; Zemon, Vance

2009-01-01

The third meeting of the Cognitive Neuroscience Treatment Research to Improve Cognition in Schizophrenia (CNTRICS) focused on selecting promising measures for each of the cognitive constructs selected in the first CNTRICS meeting. In the domain of perception, the 2 constructs of interest were gain control and visual integration. CNTRICS received 5 task nominations for gain control and three task nominations for visual integration. The breakout group for perception evaluated the degree to which each of these tasks met prespecified criteria. For gain control, the breakout group for perception believed that 2 of the tasks (prepulse inhibition of startle and mismatch negativity) were already mature and in the process of being incorporated into multisite clinical trials. However, the breakout group recommended that steady-state visual-evoked potentials be combined with contrast sensitivity to magnocellular vs parvocellular biased stimuli and that this combined task and the contrast-contrast effect task be recommended for translation for use in clinical trial contexts in schizophrenia research. For visual integration, the breakout group recommended the Contour Integration and Coherent Motion tasks for translation for use in clinical trials. This manuscript describes the ways in which each of these tasks met the criteria used by the breakout group to evaluate and recommend tasks for further development. PMID:19023123

The Nexus between the Above-Average Effect and Cooperative Learning in the Classroom

ERIC Educational Resources Information Center

Breneiser, Jennifer E.; Monetti, David M.; Adams, Katharine S.

2012-01-01

The present study examines the above-average effect (Chambers & Windschitl, 2004; Moore & Small, 2007) in assessments of task performance. Participants completed self-estimates of performance and group estimates of performance, before and after completing a task. Participants completed a task individually and in groups. Groups were…

Gender, Legitimation, and Identity Verification in Groups

ERIC Educational Resources Information Center

Burke, Peter J.; Stets, Jan E.; Cerven, Christine

2007-01-01

Drawing upon identity theory, expectation states theory, and legitimation theory, we examine how the task leader identity in task-oriented groups is more likely to be verified for persons with high status characteristics. We hypothesize that identity verification will be accomplished more readily for male group members and legitimated task leaders…

The relationship between mathematics and language: academic implications for children with specific language impairment and English language learners.

PubMed

Alt, Mary; Arizmendi, Genesis D; Beal, Carole R

2014-07-01

The present study examined the relationship between mathematics and language to better understand the nature of the deficit and the academic implications associated with specific language impairment (SLI) and academic implications for English language learners (ELLs). School-age children (N = 61; 20 SLI, 20 ELL, 21 native monolingual English [NE]) were assessed using a norm-referenced mathematics instrument and 3 experimental computer-based mathematics games that varied in language demands. Group means were compared with analyses of variance. The ELL group was less accurate than the NE group only when tasks were language heavy. In contrast, the group with SLI was less accurate than the groups with NE and ELLs on language-heavy tasks and some language-light tasks. Specifically, the group with SLI was less accurate on tasks that involved comparing numerical symbols and using visual working memory for patterns. However, there were no group differences between children with SLI and peers without SLI on language-light mathematics tasks that involved visual working memory for numerical symbols. Mathematical difficulties of children who are ELLs appear to be related to the language demands of mathematics tasks. In contrast, children with SLI appear to have difficulty with mathematics tasks because of linguistic as well as nonlinguistic processing constraints.

Effort in Multitasking: Local and Global Assessment of Effort.

PubMed

Kiesel, Andrea; Dignath, David

2017-01-01

When performing multiple tasks in succession, self-organization of task order might be superior compared to external-controlled task schedules, because self-organization allows optimizing processing modes and thus reduces switch costs, and it increases commitment to task goals. However, self-organization is an additional executive control process that is not required if task order is externally specified and as such it is considered as time-consuming and effortful. To compare self-organized and externally controlled task scheduling, we suggest assessing global subjective and objectives measures of effort in addition to local performance measures. In our new experimental approach, we combined characteristics of dual tasking settings and task switching settings and compared local and global measures of effort in a condition with free choice of task sequence and a condition with cued task sequence. In a multi-tasking environment, participants chose the task order while the task requirement of the not-yet-performed task remained the same. This task preview allowed participants to work on the previously non-chosen items in parallel and resulted in faster responses and fewer errors in task switch trials than in task repetition trials. The free-choice group profited more from this task preview than the cued group when considering local performance measures. Nevertheless, the free-choice group invested more effort than the cued group when considering global measures. Thus, self-organization in task scheduling seems to be effortful even in conditions in which it is beneficiary for task processing. In a second experiment, we reduced the possibility of task preview for the not-yet-performed tasks in order to hinder efficient self-organization. Here neither local nor global measures revealed substantial differences between the free-choice and a cued task sequence condition. Based on the results of both experiments, we suggest that global assessment of effort in addition to local performance measures might be a useful tool for multitasking research.

How Knowledge Worker Teams Deal Effectively with Task Uncertainty: The Impact of Transformational Leadership and Group Development.

PubMed

Leuteritz, Jan-Paul; Navarro, José; Berger, Rita

2017-01-01

The purpose of this paper is to clarify how leadership is able to improve team effectiveness, by means of its influence on group processes (i.e., increasing group development) and on the group task (i.e., decreasing task uncertainty). Four hundred and eight members of 107 teams in a German research and development (R&D) organization completed a web-based survey; they provided measures of transformational leadership, group development, 2 aspects of task uncertainty, task interdependence, and team effectiveness. In 54 of these teams, the leaders answered a web-based survey on team effectiveness. We tested the model with the data from team members, using structural equations modeling. Group development and a task uncertainty measurement that refers to unstable demands from outside the team partially mediate the effect of transformational leadership on team effectiveness in R&D organizations ( p < 0.05). Although transformational leaders reduce unclarity of goals ( p < 0.05), this seems not to contribute to team effectiveness. The data provided by the leaders was used to assess common source bias, which did not affect the interpretability of the results. Limitations include cross-sectional data and a lower than expected variance of task uncertainty across different job types. This paper contributes to understanding how knowledge worker teams deal effectively with task uncertainty and confirms the importance of group development in this context. This is the first study to examine the effects of transformational leadership and team processes on team effectiveness considering the task characteristics uncertainty and interdependence.

How Knowledge Worker Teams Deal Effectively with Task Uncertainty: The Impact of Transformational Leadership and Group Development

PubMed Central

Leuteritz, Jan-Paul; Navarro, José; Berger, Rita

2017-01-01

The purpose of this paper is to clarify how leadership is able to improve team effectiveness, by means of its influence on group processes (i.e., increasing group development) and on the group task (i.e., decreasing task uncertainty). Four hundred and eight members of 107 teams in a German research and development (R&D) organization completed a web-based survey; they provided measures of transformational leadership, group development, 2 aspects of task uncertainty, task interdependence, and team effectiveness. In 54 of these teams, the leaders answered a web-based survey on team effectiveness. We tested the model with the data from team members, using structural equations modeling. Group development and a task uncertainty measurement that refers to unstable demands from outside the team partially mediate the effect of transformational leadership on team effectiveness in R&D organizations (p < 0.05). Although transformational leaders reduce unclarity of goals (p < 0.05), this seems not to contribute to team effectiveness. The data provided by the leaders was used to assess common source bias, which did not affect the interpretability of the results. Limitations include cross-sectional data and a lower than expected variance of task uncertainty across different job types. This paper contributes to understanding how knowledge worker teams deal effectively with task uncertainty and confirms the importance of group development in this context. This is the first study to examine the effects of transformational leadership and team processes on team effectiveness considering the task characteristics uncertainty and interdependence. PMID:28861012

Group therapy task training versus individual task training during inpatient stroke rehabilitation: a randomised controlled trial.

PubMed

Renner, Caroline Ie; Outermans, Jacqueline; Ludwig, Ricarda; Brendel, Christiane; Kwakkel, Gert; Hummelsheim, Horst

2016-07-01

To compare the efficacy of intensive daily applied progressive group therapy task training with equally dosed individual progressive task training on self-reported mobility for patients with moderate to severe stroke during inpatient rehabilitation. Randomized controlled clinical trial. In-patient rehabilitation center. A total of 73 subacute patients with stroke who were not able to walk without physical assistance at randomisation. Patients were allocated to group therapy task training (GT) or individual task training (IT). Both interventions were intended to improve walking competency and comprised 30 sessions of 90 minutes over six weeks. Primary outcome was the mobility domain of the Stroke Impact Scale (SIS-3.0). Secondary outcomes were the other domains of SIS-3.0, standing balance, gait speed, walking distance, stair climbing, fatigue, anxiety and depression. No adverse events were reported in either arm of the trial. There were no significant differences between groups for the SIS mobility domain at the end of the intervention (Z= -0.26, P = 0.79). No significant differences between groups were found in gait speed improvements (GT:0.38 ±0.23; IT:0.26±0.35), any other gait related parameters, or in non-physical outcomes such as depression and fatigue. Inpatient group therapy task training for patients with moderate to severe stroke is safe and equally effective as a dose-matched individual task training therapy. Group therapy task training may be delivered as an alternative to individual therapy or as valuable adjunct to increase time spent in gait-related activities. © The Author(s) 2015.

Part-task vs. whole-task training on a supervisory control task

NASA Technical Reports Server (NTRS)

Battiste, Vernol

1987-01-01

The efficacy of a part-task training for the psychomotor portion of a supervisory control simulation was compared to that of the whole-task training, using six subjects in each group, who were asked to perform a task as quickly as possible. Part-task training was provided with the cursor-control device prior to transition to the whole-task. The analysis of both the training and experimental trials demonstrated a significant performance advantage for the part-task group: the tasks were performed better and at higher speed. Although the subjects finally achieved the same level of performance in terms of score, the part-task method was preferable for economic reasons, since simple pretraining systems are significantly less expensive than the whole-task training systems.

Biased information search in homogeneous groups: confidence as a moderator for the effect of anticipated task requirements.

PubMed

Kerschreiter, Rudolf; Schulz-Hardt, Stefan; Mojzisch, Andreas; Frey, Dieter

2008-05-01

When searching for information, groups that are homogeneous regarding their members' prediscussion decision preferences show a strong bias for information that supports rather than conflicts with the prevailing opinion (confirmation bias). The present research examined whether homogeneous groups blindly search for information confirming their beliefs irrespective of the anticipated task or whether they are sensitive to the usefulness of new information for this forthcoming task. Results of three experiments show that task sensitivity depends on the groups' confidence in the correctness of their decision: Moderately confident groups displayed a strong confirmation bias when they anticipated having to give reasons for their decision but showed a balanced information search or even a dis confirmation bias (i.e., predominately seeking conflicting information) when they anticipated having to refute counterarguments. In contrast, highly confident groups demonstrated a strong confirmation bias independent of the anticipated task requirements.

A test of engagement versus disengagement in catastrophe models.

PubMed

Beattie, S; Davies, M

2010-05-01

The present study explored the interactive effects of self-efficacy and increasing/decreasing task difficulty upon engagement and disengagement within a cusp-catastrophe model framework. Using a closed motor skill aiming task participants (N=60) were required to compete in conditions where task difficulty increased and then decreased (or vice versa) where they were rewarded for good performance but penalized for bad. Participants who reported low levels of self-efficacy disengage at an earlier level of task difficulty than their high self-efficacy counterparts. Furthermore, this group did not re-engage with the task until task difficulty had significantly decreased. Although task disengagement occurred with high difficulty in the high self-efficacy group, this group re-engaged in a similar manner in which they disengaged. Findings support and extend those of previous tests of catastrophe models by directly allowing for task disengagement.

Risky Decision Making Assessed With the Gambling Task in Adults with HIV

PubMed Central

Hardy, David J.; Hinkin, Charles H.; Castellon, Steven A.; Levine, Andrew J.; Lam, Mona N.

2010-01-01

Decision making was assessed using a laboratory gambling task in 67 adults with the Human Immunodeficiency Virus (HIV+) and in 19 HIV-seronegative (HIV−) control participants. Neurocognitive test performance across several domains was also analyzed to examine potential cognitive mechanisms of gambling task performance. As predicted, the HIV+ group performed worse on the gambling task, indicating greater risky decision making. Specifically, the HIV+ group selected more cards from the “risky” or disadvantageous deck that included relatively large payoffs but infrequent large penalties. The control group also selected such risky cards but quickly learned to avoid them. Exploratory analyses also indicated that in the HIV+ group, but not in the control group, gambling task performance was correlated with Stroop Interference performance and long delay free recall on the California Verbal Learning Test, suggesting the role of inhibitory processes and verbal memory in the poorer gambling task performance in HIV. These findings indicate the usefulness of the gambling task as a laboratory tool to examine risky decision making and cognition in the HIV population. PMID:16719628

An fMRI study of musicians with focal dystonia during tapping tasks.

PubMed

Kadota, Hiroshi; Nakajima, Yasoichi; Miyazaki, Makoto; Sekiguchi, Hirofumi; Kohno, Yutaka; Amako, Masatoshi; Arino, Hiroshi; Nemoto, Koichi; Sakai, Naotaka

2010-07-01

Musician's dystonia is a type of task specific dystonia for which the pathophysiology is not clear. In this study, we performed functional magnetic resonance imaging to investigate the motor-related brain activity associated with musician's dystonia. We compared brain activities measured from subjects with focal hand dystonia and normal (control) musicians during right-hand, left-hand, and both-hands tapping tasks. We found activations in the thalamus and the basal ganglia during the tapping tasks in the control group but not in the dystonia group. For both groups, we detected significant activations in the contralateral sensorimotor areas, including the premotor area and cerebellum, during each tapping task. Moreover, direct comparison between the dystonia and control groups showed that the dystonia group had greater activity in the ipsilateral premotor area during the right-hand tapping task and less activity in the left cerebellum during the both-hands tapping task. Thus, the dystonic musicians showed irregular activation patterns in the motor-association system. We suggest that irregular neural activity patterns in dystonic subjects reflect dystonic neural malfunction and consequent compensatory activity to maintain appropriate voluntary movements.

Age-related decrements in dual-task performance: Comparison of different mobility and cognitive tasks. A cross sectional study.

PubMed

Brustio, Paolo Riccardo; Magistro, Daniele; Zecca, Massimiliano; Rabaglietti, Emanuela; Liubicich, Monica Emma

2017-01-01

This cross-sectional study investigated the age-related differences in dual-task performance both in mobility and cognitive tasks and the additive dual-task costs in a sample of older, middle-aged and young adults. 74 older adults (M = 72.63±5.57 years), 58 middle-aged adults (M = 46.69±4.68 years) and 63 young adults (M = 25.34±3.00 years) participated in the study. Participants performed different mobility and subtraction tasks under both single- and dual-task conditions. Linear regressions, repeated-measures and one-way analyses of covariance were used, The results showed: significant effects of the age on the dual and mobility tasks (p<0.05) and differences among the age-groups in the combined dual-task costs (p<0.05); significant decreases in mobility performance under dual-task conditions in all groups (p<0.05) and a decrease in cognitive performance in the older group (p<0.05). Dual-task activity affected mobility and cognitive performance, especially in older adults who showed a higher dual-task cost, suggesting that dual-tasks activities are affected by the age and consequently also mobility and cognitive tasks are negatively influenced.

Sequential effects after practice with the dominant and non-dominant hand on the acquisition of a sliding task in schoolchildren.

PubMed

Senff, Oliver; Weigelt, Matthias

2011-03-01

This study was designed to investigate sequential effects after practice with the dominant and non-dominant hand on the acquisition of a new motor task. A total of 64 middle school children were asked to practise a cent-slide task, which required them to slide coins from one side of a cardboard into a circular target on the opposite side. Four groups practised this task within different practice schedules: (1) participants practised only with their dominant hand (right-only group); (2) participants used only their non-dominant hand (left-only group); (3) participants started to practise the skill with their dominant hand and then switched to their non-dominant hand (right-to-left group); or (4) participants started to practise the skill with their non-dominant hand and then switched to their dominant hand (left-to-right group). The acquisition of the task was facilitated after initial practice with the non-dominant hand. This was reflected in a better retention of the task and a stronger performance under a modified testing situation of the left-to-right group when compared to all other groups. Also, the left-only group showed larger interlimb transfer effects to the untrained hand than the right-only group. It is concluded that the sequence in which the dominant and non-dominant hands are used to practise influences the acquisition of new motor tasks.

What would you do? The effect of verbal persuasion on task choice.

PubMed

Lamarche, Larkin; Gionfriddo, Alicia M; Cline, Lindsay E; Gammage, Kimberley L; Adkin, Allan L

2014-01-01

Verbal persuasion has been shown to influence psychological and behavioral outcomes. The present study had two objectives: (1) to examine the effect of verbal persuasion on task choice in a balance setting and (2) to evaluate the use of verbal persuasion as an approach to experimentally induce mismatches between perceived and actual balance. Healthy young adults (N=68) completed an 8-m tandem walk task without vision and then were randomly assigned to a feedback group (good, control, or poor), regardless of actual balance. Following the feedback, participants chose to perform the task in one of three conditions differing in level of challenge and also were required to perform the task under the same pre-feedback conditions. Balance efficacy and perceived stability were rated before and after each pre- and post-feedback task, respectively. Balance performance measures were also collected. Following the feedback, participants in the good group were more likely to choose the most challenging task while those in the poor group were more likely to choose the least challenging task. Following the feedback, all groups showed improved balance performance. However, balance efficacy and perceived stability increased for the good and control groups but balance efficacy decreased and perceived stability was unchanged for the poor group. Thus, these findings demonstrate that verbal persuasion can influence task choice and may be used as an approach to experimentally create mismatches between perceived and actual balance. Copyright © 2013 Elsevier B.V. All rights reserved.

Classification and evaluation strategies of auto-segmentation approaches for PET: Report of AAPM task group No. 211

PubMed Central

Hatt, Mathieu; Lee, John A.; Schmidtlein, Charles R.; Naqa, Issam El; Caldwell, Curtis; De Bernardi, Elisabetta; Lu, Wei; Das, Shiva; Geets, Xavier; Gregoire, Vincent; Jeraj, Robert; MacManus, Michael P.; Mawlawi, Osama R.; Nestle, Ursula; Pugachev, Andrei B.; Schöder, Heiko; Shepherd, Tony; Spezi, Emiliano; Visvikis, Dimitris; Zaidi, Habib; Kirov, Assen S.

2017-01-01

Purpose The purpose of this educational report is to provide an overview of the present state-of-the-art PET auto-segmentation (PET-AS) algorithms and their respective validation, with an emphasis on providing the user with help in understanding the challenges and pitfalls associated with selecting and implementing a PET-AS algorithm for a particular application. Approach A brief description of the different types of PET-AS algorithms is provided using a classification based on method complexity and type. The advantages and the limitations of the current PET-AS algorithms are highlighted based on current publications and existing comparison studies. A review of the available image datasets and contour evaluation metrics in terms of their applicability for establishing a standardized evaluation of PET-AS algorithms is provided. The performance requirements for the algorithms and their dependence on the application, the radiotracer used and the evaluation criteria are described and discussed. Finally, a procedure for algorithm acceptance and implementation, as well as the complementary role of manual and auto-segmentation are addressed. Findings A large number of PET-AS algorithms have been developed within the last 20 years. Many of the proposed algorithms are based on either fixed or adaptively selected thresholds. More recently, numerous papers have proposed the use of more advanced image analysis paradigms to perform semi-automated delineation of the PET images. However, the level of algorithm validation is variable and for most published algorithms is either insufficient or inconsistent which prevents recommending a single algorithm. This is compounded by the fact that realistic image configurations with low signal-to-noise ratios (SNR) and heterogeneous tracer distributions have rarely been used. Large variations in the evaluation methods used in the literature point to the need for a standardized evaluation protocol. Conclusions Available comparison studies suggest that PET-AS algorithms relying on advanced image analysis paradigms provide generally more accurate segmentation than approaches based on PET activity thresholds, particularly for realistic configurations. However, this may not be the case for simple shape lesions in situations with a narrower range of parameters, where simpler methods may also perform well. Recent algorithms which employ some type of consensus or automatic selection between several PET-AS methods have potential to overcome the limitations of the individual methods when appropriately trained. In either case, accuracy evaluation is required for each different PET scanner and scanning and image reconstruction protocol. For the simpler, less robust approaches, adaptation to scanning conditions, tumor type, and tumor location by optimization of parameters is necessary. The results from the method evaluation stage can be used to estimate the contouring uncertainty. All PET-AS contours should be critically verified by a physician. A standard test, i.e., a benchmark dedicated to evaluating both existing and future PET-AS algorithms needs to be designed, to aid clinicians in evaluating and selecting PET-AS algorithms and to establish performance limits for their acceptance for clinical use. The initial steps toward designing and building such a standard are undertaken by the task group members. PMID:28120467

Training working memory in older adults: Is there an advantage of using strategies?

PubMed

Borella, Erika; Carretti, Barbara; Sciore, Roberta; Capotosto, Emanuela; Taconnat, Laurence; Cornoldi, Cesare; De Beni, Rossana

2017-03-01

The purpose of the present study was to test the efficacy of a working memory (WM) training in elderly people, and to compare the effects of a WM training based on an adaptive procedure with one combining the same procedure with the use of a strategy, based on the construction of visual mental images. Eighteen older adults received training with a WM task (the WM group), another 18 received the same WM training and were also taught to use a visual imagery strategy (the WM + Strategy group), and another 18 served as active controls. Training-related gains in the WM (criterion) task and transfer effects on measures of verbal and visuospatial WM, short-term memory (STM), processing speed, and reasoning were considered. Training gains and transfer effects were also assessed after 6 months. After the training, both the trained groups performed better than the control group in the WM criterion task, and maintained these gains 6 months later; they also showed immediate transfer effects on processing speed. The two trained groups also outperformed the control group in the long term in the WM tasks, in one of the STM tasks (backward span task), and in the processing speed measure. Long-term large effect sizes were found for all the tasks involving memory processes in the WM + Strategy group, but only for the processing speed task in the WM group. Findings are discussed in terms of the benefits and limits of teaching older people a strategy in combination with an adaptive WM training. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Task-related functional connectivity in autism spectrum conditions: an EEG study using wavelet transform coherence

PubMed Central

2013-01-01

Background Autism Spectrum Conditions (ASC) are a set of pervasive neurodevelopmental conditions characterized by a wide range of lifelong signs and symptoms. Recent explanatory models of autism propose abnormal neural connectivity and are supported by studies showing decreased interhemispheric coherence in individuals with ASC. The first aim of this study was to test the hypothesis of reduced interhemispheric coherence in ASC, and secondly to investigate specific effects of task performance on interhemispheric coherence in ASC. Methods We analyzed electroencephalography (EEG) data from 15 participants with ASC and 15 typical controls, using Wavelet Transform Coherence (WTC) to calculate interhemispheric coherence during face and chair matching tasks, for EEG frequencies from 5 to 40 Hz and during the first 400 ms post-stimulus onset. Results Results demonstrate a reduction of interhemispheric coherence in the ASC group, relative to the control group, in both tasks and for all electrode pairs studied. For both tasks, group differences were generally observed after around 150 ms and at frequencies lower than 13 Hz. Regarding within-group task comparisons, while the control group presented differences in interhemispheric coherence between faces and chairs tasks at various electrode pairs (FT7-FT8, TP7-TP8, P7-P8), such differences were only seen for one electrode pair in the ASC group (T7-T8). No significant differences in EEG power spectra were observed between groups. Conclusions Interhemispheric coherence is reduced in people with ASC, in a time and frequency specific manner, during visual perception and categorization of both social and inanimate stimuli and this reduction in coherence is widely dispersed across the brain. Results of within-group task comparisons may reflect an impairment in task differentiation in people with ASC relative to typically developing individuals. Overall, the results of this research support the value of WTC in examining the time-frequency microstructure of task-related interhemispheric EEG coherence in people with ASC. PMID:23311570

Task based exposure assessment in ergonomic epidemiology: a study of upper arm elevation in the jobs of machinists, car mechanics, and house painters

PubMed Central

Svendsen, S; Mathiassen, S; Bonde, J

2005-01-01

Aims: To explore the precision of task based estimates of upper arm elevation in three occupational groups, compared to direct measurements of job exposure. Methods: Male machinists (n = 26), car mechanics (n = 23), and house painters (n = 23) were studied. Whole day recordings of upper arm elevation were obtained for four consecutive working days, and associated task information was collected in diaries. For each individual, task based estimates of job exposure were calculated by weighting task exposures from a collective database by task proportions according to the diaries. These estimates were validated against directly measured job exposures using linear regression. The performance of the task based approach was expressed through the gain in precision of occupational group mean exposures that could be obtained by adding subjects with task based estimates to a group of subjects with measured job exposures in a "validation" design. Results: In all three occupations, tasks differed in mean exposure, and task proportions varied between individuals. Task based estimation proved inefficient, with squared correlation coefficients only occasionally exceeding 0.2 for the relation between task based and measured job exposures. Consequently, it was not possible to substantially improve the precision of an estimated group mean by including subjects whose job exposures were based on task information. Conclusions: Task based estimates of mechanical job exposure can be very imprecise, and only marginally better than estimates based on occupation. It is recommended that investigators in ergonomic epidemiology consider the prospects of task based exposure assessment carefully before placing resources at obtaining task information. Strategies disregarding tasks may be preferable in many cases. PMID:15613604

Context matters: Social cognition task performance in psychometric schizotypes.

PubMed

Pflum, Madeline J; Gooding, Diane C

2018-06-01

Patients with schizophrenia show performance deficits on tasks requiring empathy-related social cognition. The extent to which empathy impairments are observed in psychometric schizotypy is unclear. We compared accuracy and reaction time in three groups of individuals characterized by positive schizotypy (n = 79), negative schizotypy (n = 123), or low schizotypy group (n = 137). On a social cognition task that provided context, namely, the Emotion Perspective Taking Task, the positive schizotypes showed poorer performance than the negative schizotypy and control groups. These results suggest that some schizotypes differ in their ability to make use of context (e.g., social cues from the environment) to affect their social cognitive performance. However, on the Affective Responsiveness Task, in which no context was given, both groups of psychometric schizotypes displayed lower performance than the controls. These findings highlight the importance of assessing multiple groups of schizotypes as well as the value of including several social cognition tasks in order to reveal relative performance deficits. Copyright © 2018 Elsevier B.V. All rights reserved.

Effects of Relaxing Music on Mental Fatigue Induced by a Continuous Performance Task: Behavioral and ERPs Evidence.

PubMed

Guo, Wei; Ren, Jie; Wang, Biye; Zhu, Qin

2015-01-01

The purpose of this study was to investigate whether listening to relaxing music would help reduce mental fatigue and to maintain performance after a continuous performance task. The experiment involved two fatigue evaluation phases carried out before and after a fatigue inducing phase. A 1-hour AX-continuous performance test was used to induce mental fatigue in the fatigue-inducing phase, and participants' subjective evaluation on the mental fatigue, as well as their neurobehavioral performance in a Go/NoGo task, were measured before and after the fatigue-inducing phase. A total of 36 undergraduate students (18-22 years) participated in the study and were randomly assigned to the music group and control group. The music group performed the fatigue-inducing task while listening to relaxing music, and the control group performed the same task without any music. Our results revealed that after the fatigue-inducing phase, (a) the music group demonstrated significantly less mental fatigue than control group, (b) reaction time significantly increased for the control group but not for the music group, (c) larger Go-P3 and NoGo-P3 amplitudes were observed in the music group, although larger NoGo-N2 amplitudes were detected for both groups. These results combined to suggest that listening to relaxing music alleviated the mental fatigue associated with performing an enduring cognitive-motor task.

Phonological short-term memory in logopenic variant primary progressive aphasia and mild Alzheimer's disease.

PubMed

Meyer, Aaron M; Snider, Sarah F; Campbell, Rachael E; Friedman, Rhonda B

2015-10-01

It has been argued that individuals with logopenic variant primary progressive aphasia (lvPPA) have an impairment of the phonological loop, which is a component of the short-term memory (STM) system. In contrast, this type of impairment is not thought to be present in mild typical Alzheimer's disease (AD). Thus, one would predict that people with lvPPA would score significantly lower than a matched AD group on tasks that require phonological STM. In the current study, an lvPPA group was compared with a mild AD group that was matched on age, education, and general cognitive functioning. For a subset of the tasks that involved pseudowords, the AD and lvPPA groups were compared to a healthy control group that was matched on age and education. The lvPPA group was more impaired than the AD group on all of the tasks that required phonological STM, including the pseudoword tasks, but there were no significant differences between these groups on tasks that required visuospatial STM. Compared to the healthy controls, the lvPPA group performed significantly worse on the repetition and reading of pseudowords, while the AD group did not differ significantly from the controls on these tasks. These findings are consistent with the hypothesis that phonological STM is impaired in lvPPA. Copyright © 2015 Elsevier Ltd. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mandapaka, A; Ghebremedhin, A; Farley, D

Purpose: To develop the methodology to evaluate the clinical performance of a Phase II Proton CT scanner Methods: Range errors on the order of 3%-5% constitute a major uncertainty in current charged particle treatment planning based on Hounsfield Unit (HU)-relative stopping power (RSP) calibration curves. Within our proton CT collaboration, we previously developed and built a Phase I proton CT scanner that provided a sensitive area of 9 cm (axial) × 18 cm (in-plane). This scanner served to get initial experience with this new treatment planning tool and to incorporate lessons learned into the next generation design. A Phase IImore » scanner was recently completed and is now undergoing initial performance testing. It will increase the proton acquisition rate and provide a larger detection area of 9 cm x 36 cm. We are now designing a comprehensive evaluation program to test the image quality, imaging dose, and range uncertainty associated with this scanner. The testing will be performed along the lines of AAPM TG 66. Results: In our discussion of the evaluation protocol we identified the following priorities. The image quality of proton CT images, in particular spatial resolution and low-density contrast discrimination, will be evaluated with the Catphan600 phantom. Initial testing showed that the Catphan uniformity phantom did not provide sufficient uniformity; it was thus replaced by a cylindrical water phantom. The imaging dose will be tested with a Catphan dose module, and compared to a typical cone beam CT dose for comparable image quality. Lastly, we developed a dedicated dosimetry range phantom based on the CIRS pediatric head phantom HN715. Conclusion: A formal evaluation of proton CT as a new tool for proton treatment planning is an important task. The availability of the new Phase II proton CT scanner will allow us to perform this task. This research is supported by the National Institute of Biomedical Imaging and Bioengineering of the NIH under award number R01EB013118. The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH.« less

The effects of proportional representation and gender orientation of the task on emergent leadership behavior in mixed-gender work groups.

PubMed

Karakowsky, L; Siegel, J P

1999-08-01

Much of the research that has examined the behavioral consequences of membership in mixed-gender work groups suggests that men are more participative and influential in task-related behavior. Drawing from elements of sociological, structural, and psychological perspectives, this study examined the effects of group gender composition and gender orientation of the group's task on patterns of emergent leadership behavior. Participants were assigned to male-dominated, female-dominated, or balanced-gender groups for the purpose of discussing and generating solutions for two business-related cases--each case emphasized either male-oriented or female-oriented expertise. The findings suggest that the proportional representation of men and women in a work group, along with the gender orientation of the group's task, can significantly influence the level of leadership behavior exhibited in group activity.

Effects of the Addition of a Dual Task to a Supervised Physical Exercise Program on Older Adults' Cognitive Performance.

PubMed

Ansai, Juliana Hotta; de Andrade, Larissa Pires; de Souza Buto, Marcele Stephanie; de Vassimon Barroso, Verena; Farche, Ana Claudia Silva; Rossi, Paulo Giusti; de Medeiros Takahashi, Anielle Cristhine

2017-04-01

The purpose of this study was to investigate the effects of the addition of a dual task to multicomponent training on cognition of active older adults. Eighty physically active older adults were divided into an intervention group (IG) and a control group (CG). Both groups performed multicomponent training over 12 weeks. The IG simultaneously performed exercises and cognitive tasks. The Mini-Mental State Examination, the Montreal Cognitive Assessment, and the Clock Drawing Test were used for cognitive assessments. The Timed Up and Go Test associated with a cognitive task was used for dual-task assessment. Significant interactions were not observed between groups in terms of the cognitive variables or the dual-task performance. An interaction was observed only for Timed Up and Go Test performance, which was better in the CG than in the IG. Active older adults showed no improvement in cognition following the addition of the dual task to the multicomponent training.

Learning redundant motor tasks with and without overlapping dimensions: facilitation and interference effects.

PubMed

Ranganathan, Rajiv; Wieser, Jon; Mosier, Kristine M; Mussa-Ivaldi, Ferdinando A; Scheidt, Robert A

2014-06-11

Prior learning of a motor skill creates motor memories that can facilitate or interfere with learning of new, but related, motor skills. One hypothesis of motor learning posits that for a sensorimotor task with redundant degrees of freedom, the nervous system learns the geometric structure of the task and improves performance by selectively operating within that task space. We tested this hypothesis by examining if transfer of learning between two tasks depends on shared dimensionality between their respective task spaces. Human participants wore a data glove and learned to manipulate a computer cursor by moving their fingers. Separate groups of participants learned two tasks: a prior task that was unique to each group and a criterion task that was common to all groups. We manipulated the mapping between finger motions and cursor positions in the prior task to define task spaces that either shared or did not share the task space dimensions (x-y axes) of the criterion task. We found that if the prior task shared task dimensions with the criterion task, there was an initial facilitation in criterion task performance. However, if the prior task did not share task dimensions with the criterion task, there was prolonged interference in learning the criterion task due to participants finding inefficient task solutions. These results show that the nervous system learns the task space through practice, and that the degree of shared task space dimensionality influences the extent to which prior experience transfers to subsequent learning of related motor skills. Copyright © 2014 the authors 0270-6474/14/348289-11$15.00/0.

Beyond the real world: attention debates in auditory mismatch negativity.

PubMed

Chung, Kyungmi; Park, Jin Young

2018-04-11

The aim of this study was to address the potential for the auditory mismatch negativity (aMMN) to be used in applied event-related potential (ERP) studies by determining whether the aMMN would be an attention-dependent ERP component and could be differently modulated across visual tasks or virtual reality (VR) stimuli with different visual properties and visual complexity levels. A total of 80 participants, aged 19-36 years, were assigned to either a reading-task (21 men and 19 women) or a VR-task (22 men and 18 women) group. Two visual-task groups of healthy young adults were matched in age, sex, and handedness. All participants were instructed to focus only on the given visual tasks and ignore auditory change detection. While participants in the reading-task group read text slides, those in the VR-task group viewed three 360° VR videos in a random order and rated how visually complex the given virtual environment was immediately after each VR video ended. Inconsistent with the finding of a partial significant difference in perceived visual complexity in terms of brightness of virtual environments, both visual properties of distance and brightness showed no significant differences in the modulation of aMMN amplitudes. A further analysis was carried out to compare elicited aMMN amplitudes of a typical MMN task and an applied VR task. No significant difference in the aMMN amplitudes was found across the two groups who completed visual tasks with different visual-task demands. In conclusion, the aMMN is a reliable ERP marker of preattentive cognitive processing for auditory deviance detection.

Characterization of nanoDot optically stimulated luminescence detectors and high-sensitivity MCP-N thermoluminescent detectors in the 40-300 kVp energy range.

PubMed

Poirier, Yannick; Kuznetsova, Svetlana; Villarreal-Barajas, Jose Eduardo

2018-01-01

To investigate empirically the energy dependence of the detector response of two in vivo luminescence detectors, LiF:Mg,Cu,P (MCP-N) high-sensitivity TLDs and Al 2 O 3 :C OSLDs, in the 40-300-kVp energy range in the context of in vivo surface dose measurement. As these detectors become more prevalent in clinical and preclinical in vivo measurements, knowledge of the variation in the empirical dependence of the measured response of these detectors across a wide spectrum of beam qualities is important. We characterized a large range of beam qualities of three different kilovoltage x-ray units: an Xstrahl 300 Orthovoltage unit, a Precision x-Ray X-RAD 320ix biological irradiator, and a Varian On-Board Imaging x-ray unit. The dose to water was measured in air according to the AAPM's Task Group 61 protocol. The OSLDs and TLDs were irradiated under reference conditions on the surface of a water phantom to provide full backscatter conditions. To assess the change in sensitivity in the long term, we separated the in vivo dosimeters of each type into an experimental and a reference group. The experimental dosimeters were irradiated using the kilovoltage x-ray units at each beam quality used in this investigation, while the reference group received a constant 10 cGy irradiation at 6 MV from a Varian clinical linear accelerator. The individual calibration of each detector was verified in cycles where both groups received a 10 cGy irradiation at 6 MV. The nanoDot OSLDs were highly reproducible, with ±1.5% variation in response following >40 measurement cycles. The TLDs lost ~20% of their signal sensitivity over the course of the study. The relative light output per unit dose to water of the MCP-N TLDs did not vary with beam quality for beam qualities with effective energies <50 keV (~150 kVp/6 mm Al). At higher energies, they showed a reduced (~75-85%) light output per unit dose relative to 6 MV x rays. The nanoDot OSLDs exhibited a very strong (120-408%) dependency of the light output relative to 6 MV x rays. Variations up to 15% between different x-ray units with equivalent effective energies were also observed. While convenient for clinical use, nanoDot OSLDs exhibit a strong variation in their measured light output per unit dose relative to 6 MV in the 40-300 kV x-ray range. This variability differs unit-to-unit, limiting their effective use for in vivo dosimetry applications in the kilovoltage x-ray energy range. MCP-N TLDs offer a much more stable response, but suffer from variations in sensitivity over time dependent on radiation history, which requires careful experimental handling. © 2017 American Association of Physicists in Medicine.

The relationship between internet-gaming experience and executive functions measured by virtual environment compared with conventional laboratory multitasks.

PubMed

Chen, Yong-Quan; Hsieh, Shulan

2018-01-01

The aim of this study was to investigate if individuals with frequent internet gaming (IG) experience exhibited better or worse multitasking ability compared with those with infrequent IG experience. The individuals' multitasking abilities were measured using virtual environment multitasks, such as Edinburgh Virtual Errands Test (EVET), and conventional laboratory multitasks, such as the dual task and task switching. Seventy-two young healthy college students participated in this study. They were split into two groups based on the time spent on playing online games, as evaluated using the Internet Use Questionnaire. Each participant performed EVET, dual-task, and task-switching paradigms on a computer. The current results showed that the frequent IG group performed better on EVET compared with the infrequent IG group, but their performance on the dual-task and task-switching paradigms did not differ significantly. The results suggest that the frequent IG group exhibited better multitasking efficacy if measured using a more ecologically valid task, but not when measured using a conventional laboratory multitasking task. The differences in terms of the subcomponents of executive function measured by these task paradigms were discussed. The current results show the importance of the task effect while evaluating frequent internet gamers' multitasking ability.

The relationship between internet-gaming experience and executive functions measured by virtual environment compared with conventional laboratory multitasks

PubMed Central

Chen, Yong-Quan

2018-01-01

The aim of this study was to investigate if individuals with frequent internet gaming (IG) experience exhibited better or worse multitasking ability compared with those with infrequent IG experience. The individuals’ multitasking abilities were measured using virtual environment multitasks, such as Edinburgh Virtual Errands Test (EVET), and conventional laboratory multitasks, such as the dual task and task switching. Seventy-two young healthy college students participated in this study. They were split into two groups based on the time spent on playing online games, as evaluated using the Internet Use Questionnaire. Each participant performed EVET, dual-task, and task-switching paradigms on a computer. The current results showed that the frequent IG group performed better on EVET compared with the infrequent IG group, but their performance on the dual-task and task-switching paradigms did not differ significantly. The results suggest that the frequent IG group exhibited better multitasking efficacy if measured using a more ecologically valid task, but not when measured using a conventional laboratory multitasking task. The differences in terms of the subcomponents of executive function measured by these task paradigms were discussed. The current results show the importance of the task effect while evaluating frequent internet gamers’ multitasking ability. PMID:29879150

The Impact of a Sports Vision Training Program in Youth Field Hockey Players

PubMed Central

Schwab, Sebastian; Memmert, Daniel

2012-01-01

The aim of this study was to investigate whether a sports vision training program improves the visual performance of youth male field hockey players, ages 12 to 16 years, after an intervention of six weeks compared to a control group with no specific sports vision training. The choice reaction time task at the D2 board (Learning Task I), the functional field of view task (Learning Task II) and the multiple object tracking (MOT) task (Transfer Task) were assessed before and after the intervention and again six weeks after the second test. Analyzes showed significant differences between the two groups for the choice reaction time task at the D2 board and the functional field of view task, with significant improvements for the intervention group and none for the control group. For the transfer task, we could not find statistically significant improvements for either group. The results of this study are discussed in terms of theoretical and practical implications. Key pointsPerceptual training with youth field hockey playersCan a sports vision training program improve the visual performance of youth male field hockey players, ages 12 to 16 years, after an intervention of six weeks compared to a control group with no specific sports vision training?The intervention was performed in the “VisuLab” as DynamicEye® SportsVision Training at the German Sport University Cologne.We ran a series of 3 two-factor univariate analysis of variance (ANOVA) with repeated measures on both within subject independent variables (group; measuring point) to examine the effects on central perception, peripheral perception and choice reaction time.The present study shows an improvement of certain visual abilities with the help of the sports vision training program. PMID:24150071

Aging of theory of mind: the influence of educational level and cognitive processing.

PubMed

Li, Xiaoming; Wang, Kai; Wang, Fan; Tao, Qian; Xie, Yu; Cheng, Qi

2013-01-01

Previous studies of theory of mind (ToM) in old age have provided mixed results. We predicted that educational level and cognitive processing are two factors influencing the pattern of the aging of ToM. To test this hypothesis, a younger group who received higher education (mean age 20.46 years), an older group with an education level equal to that of the young group (mean age 76.29 years), and an older group with less education (mean age 73.52 years) were recruited. ToM tasks included the following tests: the second-order false-belief task, the faux-pas task, the eyes test, and tests of fundamental aspects of cognitive function that included two background tests (memory span and processing speed) and three subcomponents of executive function (inhibition, updating, and shifting). We found that the younger group and the older group with equally high education outperformed the older group with less education in false-belief and faux-pas tasks. However, there was no significant difference between the two former groups. The three groups of participants performed equivalently in the eyes test as well as in control tasks (false-belief control question, faux-pas control question, faux-pas control story, and Eyes Test control task). The younger group outperformed the other two groups in the cognitive processing tasks. Mediation analyses showed that difficulties in inhibition, memory span, and processing speed mediated the age differences in false-belief reasoning. Also, the variables of inhibition, updating, memory span, and processing speed mediated age-related variance in faux-pas. Discussion focused on the links between ToM aging, educational level, and cognitive processing. Supported by Chinese National Natural Science Foundation (number: 30870766) and Anhui Province Natural Science Foundation (number: 11040606M166).

Breaking a habit: a further role of the phonological loop in action control.

PubMed

Saeki, Erina; Baddeley, Alan D; Hitch, Graham J; Saito, Satoru

2013-10-01

Recent research has suggested that keeping track of a task goal in rapid task switching may depend on the phonological loop component of working memory. In this study, we investigated whether the phonological loop plays a similar role when a single switch extending over several trials is required after many trials on which one has performed a competing task. Participants were shown pairs of digits varying in numerical and physical size, and they were required to decide which digit was numerically or physically larger. An experimental cycle consisted of four blocks of 24 trials. In Experiment 1, participants in the task change groups performed the numerical-size judgment task during the first three blocks, and then changed to the physical-size judgment task in the fourth. Participants in the continuation groups performed only the physical-size judgment task throughout all four blocks. We found negative effects of articulatory suppression on the fourth block, but only in the task change groups. Experiment 2 was a replication, with the modification that both groups received identical instructions and practice. Experiment 3 was a further replication using numerical-size judgment as the target task. The results showed a pattern similar to that from Experiment 1, with negative effects of articulatory suppression found only in the task change group. The congruity of numerical and physical size had a reliable effect on performance in all three experiments, but unlike the task change, it did not reliably interact with articulatory suppression. The results suggest that in addition to its well-established role in rapid task switching, the phonological loop also contributes to active goal maintenance in longer-term action control.

Effects of disease severity and medication state on postural control asymmetry during challenging postural tasks in individuals with Parkinson's disease.

PubMed

Barbieri, Fabio A; Polastri, Paula F; Baptista, André M; Lirani-Silva, Ellen; Simieli, Lucas; Orcioli-Silva, Diego; Beretta, Victor S; Gobbi, Lilian T B

2016-04-01

The aim of this study was to investigate the effects of disease severity and medication state on postural control asymmetry during challenging tasks in individuals with Parkinson's disease (PD). Nineteen people with PD and 11 neurologically healthy individuals performed three standing task conditions: bipedal standing, tandem and unipedal adapted standing; the individuals with PD performed the tasks in ON and OFF medication state. The participants with PD were distributed into 2 groups according to disease severity: unilateral group (n=8) and bilateral group (n=11). The two PD groups performed the evaluations both under and without the medication. Two force plates were used to analyze the posture. The symmetric index was calculated for various of center of pressure. ANOVA one-way (groups) and two-way (PD groups×medication), with repeated measures for medication, were calculated. For main effects of group, the bilateral group was more asymmetric than CG. For main effects of medication, only unipedal adapted standing presented effects of PD medication. There was PD groups×medication interaction. Under the effects of medication, the unilateral group presented lower asymmetry of RMS in anterior-posterior direction and area than the bilateral group in unipedal adapted standing. In addition, the unilateral group presented lower asymmetry of mean velocity, RMS in anterior-posterior direction and area in unipedal standing and area in tandem adapted standing after a medication dose. Postural control asymmetry during challenging postural tasks was dependent on disease severity and medication state in people with PD. The bilateral group presented higher postural control asymmetry than the control and unilateral groups in challenging postural tasks. Finally, the medication dose was able to reduce postural control asymmetry in the unilateral group during challenging postural tasks. Copyright © 2015 Elsevier B.V. All rights reserved.

[Assessment of cerebral oxygen saturation using near infrared spectroscopy under driver fatigue state].

PubMed

Li, Zeng-yong; Dai, Shi-xun; Zhang, Xiao-yin; Li, Yue; Yu, Xing-xin

2010-01-01

The objective of the present study is to assess the cerebral saturation under driver fatigue based on the near infrared spectroscopy (NIRS) signals. Twenty healthy male subjects were randomly divided into two groups: A-group (study group) and B-group (control group). All subjects were required to be well rested before the experiment. In A-group the subjects were required to perform the simulated driving task for 3 hours. Cerebral oxygenation signal was monitored for 20 minutes prior to and after the prescribed task period from the left frontal lobe. The results show that cerebral oxygen saturation was found to be significantly lower following 3-hour driving in the task group compared to that in the control group (F = 15.92, p < 0.001). Also a significant difference in selective reaction time was observed between the task group and control group during the post task period (p = 0.021). These findings showed that the cerebral blood oxygen saturation was closely related to the driver fatigue. The decline of the cerebral oxygen saturation might indicate a reduced cerebral oxygen delivery. This suggests that NIRS could provide a non-invasive method to detect driver fatigue.

Effects of Strategy Instruction on the Learning, Use, and Vertical Transfer of Strategies.

ERIC Educational Resources Information Center

Finley, Fred N.; Smith, Edward L.

1980-01-01

Compares group differences in strategy learning, use, and transfer to a more complex task for two groups of elementary students (N=48). Asked to perform three tasks in classifying igneous rocks, the groups differed in whether they received advice on the use of a specific strategy for performing each task. (CS)

Postural Adaptations to a Suprapostural Memory Task among Children with and without Developmental Coordination Disorder

ERIC Educational Resources Information Center

Chen, Fu-Chen; Tsai, Chia-Liang; Stoffregen, Thomas A.; Chang, Chihu-Hui; Wade, Michael G.

2012-01-01

Aim: The present study investigated the effects of varying the cognitive demands of a memory task (a suprapostural task) while recording postural motion on two groups of children, one diagnosed with developmental coordination disorder (DCD) and an age-matched group of typically developing children. Method: Two groups, each comprising 38 child…

Performance predictions affect attentional processes of event-based prospective memory.

PubMed

Rummel, Jan; Kuhlmann, Beatrice G; Touron, Dayna R

2013-09-01

To investigate whether making performance predictions affects prospective memory (PM) processing, we asked one group of participants to predict their performance in a PM task embedded in an ongoing task and compared their performance with a control group that made no predictions. A third group gave not only PM predictions but also ongoing-task predictions. Exclusive PM predictions resulted in slower ongoing-task responding both in a nonfocal (Experiment 1) and in a focal (Experiment 2) PM task. Only in the nonfocal task was the additional slowing accompanied by improved PM performance. Even in the nonfocal task, however, was the correlation between ongoing-task speed and PM performance reduced after predictions, suggesting that the slowing was not completely functional for PM. Prediction-induced changes could be avoided by asking participants to additionally predict their performance in the ongoing task. In sum, the present findings substantiate a role of metamemory for attention-allocation strategies of PM. Copyright © 2013 Elsevier Inc. All rights reserved.

Dual-task performance involving hand dexterity and cognitive tasks and daily functioning in people with schizophrenia: a pilot study.

PubMed

Lin, Keh-chung; Wu, Yi-fang; Chen, I-chen; Tsai, Pei-luen; Wu, Ching-yi; Chen, Chia-ling

2015-01-01

This study investigated separate and concurrent performance on cognitive and hand dexterity tasks and the relationship to daily functioning in 16 people with schizophrenia and 16 healthy control participants. Participants performed the Purdue Pegboard Test and the Serial Seven Subtraction Test under single- and dual-task conditions and completed two daily functioning evaluations. The hand dexterity of all participants declined in the dual-task condition, but the discrepancy between single-task and dual-task hand dexterity was greater in the schizophrenia group than in the control group (p<.03, d>.70, for all). The extent of discrepancy in hand dexterity was negatively correlated with daily functioning in the schizophrenia group (rs=-.3 to -.5, ps=.04-.26). Ability to perform dual tasks may be an indicator of daily functioning in people with schizophrenia. Use of dual-task training may be considered as a therapeutic activity with these clients. Copyright © 2015 by the American Occupational Therapy Association, Inc.

Age-related decrements in dual-task performance: Comparison of different mobility and cognitive tasks. A cross sectional study

PubMed Central

Brustio, Paolo Riccardo; Zecca, Massimiliano; Rabaglietti, Emanuela; Liubicich, Monica Emma

2017-01-01

This cross-sectional study investigated the age-related differences in dual-task performance both in mobility and cognitive tasks and the additive dual-task costs in a sample of older, middle-aged and young adults. 74 older adults (M = 72.63±5.57 years), 58 middle-aged adults (M = 46.69±4.68 years) and 63 young adults (M = 25.34±3.00 years) participated in the study. Participants performed different mobility and subtraction tasks under both single- and dual-task conditions. Linear regressions, repeated-measures and one-way analyses of covariance were used, The results showed: significant effects of the age on the dual and mobility tasks (p<0.05) and differences among the age-groups in the combined dual-task costs (p<0.05); significant decreases in mobility performance under dual-task conditions in all groups (p<0.05) and a decrease in cognitive performance in the older group (p<0.05). Dual-task activity affected mobility and cognitive performance, especially in older adults who showed a higher dual-task cost, suggesting that dual-tasks activities are affected by the age and consequently also mobility and cognitive tasks are negatively influenced. PMID:28732080

The effect of deep brain stimulation of the subthalamic nucleus on executive functions: impaired verbal fluency and intact updating, planning and conflict resolution in Parkinson's disease.

PubMed

Demeter, Gyula; Valálik, István; Pajkossy, Péter; Szőllősi, Ágnes; Lukács, Ágnes; Kemény, Ferenc; Racsmány, Mihály

2017-04-24

Although the improvement of motor symptoms in Parkinson's disease (PD) after deep brain stimulation (DBS) of the subthalamic nucleus (STN) is well documented, there are open questions regarding its impact on cognitive functions. The aim of this study was to assess the effect of bilateral DBS of the STN on executive functions in PD patients using a DBS wait-listed PD control group. Ten PD patients with DBS implantation (DBS group) and ten PD wait-listed patients (Clinical control group) participated in the study. Neuropsychological tasks were used to assess general mental ability and various executive functions. Each task was administered twice to each participant: before and after surgery (with the stimulators on) in the DBS group and with a matched delay between the two task administration points in the control group. There was no significant difference between the DBS and the control groups' performance in tasks measuring the updating of verbal, spatial or visual information (Digit span, Corsi and N-back tasks), planning and shifting (Trail Making B), and conflict resolution (Stroop task). However, the DBS group showed a significant decline on the semantic verbal fluency task after surgery compared to the control group, which is in line with findings of previous studies. Our results provide support for the relative cognitive safety of the STN DBS using a wait-listed PD control group. Differential effects of the STN DBS on frontostriatal networks are discussed. Copyright © 2017 Elsevier B.V. All rights reserved.

Visual search performance in the autism spectrum II: the radial frequency search task with additional segmentation cues.

PubMed

Almeida, Renita A; Dickinson, J Edwin; Maybery, Murray T; Badcock, Johanna C; Badcock, David R

2010-12-01

The Embedded Figures Test (EFT) requires detecting a shape within a complex background and individuals with autism or high Autism-spectrum Quotient (AQ) scores are faster and more accurate on this task than controls. This research aimed to uncover the visual processes producing this difference. Previously we developed a search task using radial frequency (RF) patterns with controllable amounts of target/distracter overlap on which high AQ participants showed more efficient search than low AQ observers. The current study extended the design of this search task by adding two lines which traverse the display on random paths sometimes intersecting target/distracters, other times passing between them. As with the EFT, these lines segment and group the display in ways that are task irrelevant. We tested two new groups of observers and found that while RF search was slowed by the addition of segmenting lines for both groups, the high AQ group retained a consistent search advantage (reflected in a shallower gradient for reaction time as a function of set size) over the low AQ group. Further, the high AQ group were significantly faster and more accurate on the EFT compared to the low AQ group. That is, the results from the present RF search task demonstrate that segmentation and grouping created by intersecting lines does not further differentiate the groups and is therefore unlikely to be a critical factor underlying the EFT performance difference. However, once again, we found that superior EFT performance was associated with shallower gradients on the RF search task. Copyright © 2010 Elsevier Ltd. All rights reserved.

WE-A-207-01: Memorial Lecturer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Muller-Runkel, R

The Medical Physics community lost one of its early pioneers in radiation oncology physics, Jacques Ovadia, who passed away in April of 2014 at the age of 90. Jacques received his Ph.D. in Nuclear Physics from the University of Illinois at Urbana in 1951. Subsequently, under the guidance of John Laughlin, he was introduced to the field of Medical Physics. When John moved to Memorial Sloan Kettering, Jacques followed him. There he gained clinical experience and expertise in the then cutting-edge field of high energy electron beam therapy. In 1956, Jacques joined Dr. Erich Uhlmann at Michael Reese Hospital inmore » Chicago where one of the country’s first high energy medical linear accelerators had just been installed. During his 35 year tenure, Dr. Ovadia built a strong Medical Physics department that merged in 1984 with that of the University of Chicago. Jacques pioneered the use of high energy electron beams to treat deep seated tumors, multiple-field chest wall irradiation with variable electron energies, and even anticipated the current interest in high energy electron beam grid-therapy. At an early stage, he introduced a simulator, computerized treatment planning and in-house developed record and verify software. He retired in 1990 as Professor emeritus in Radiation and Cellular Biology at the University of Chicago. Dr. Ovadia was an early and strong supporter of AAPM. He was present at the Chicago ROMPS meeting where the decision was made to form an independent professional society for medical physics. He served as AAPM president in 1976. Jacques Ovadia is survived by his wife of 58 years, Florence, their daughter Corinne Graefe and son Marc Ovadia, MD, as well as four grandchildren and one great-grandchild. Jacques’ dynamic and ever enthusiastic personality inspired all who collaborated with him. He will be greatly missed.« less

Monte Carlo dosimetric characterization of the Flexisource Co-60 high-dose-rate brachytherapy source using PENELOPE.

PubMed

Almansa, Julio F; Guerrero, Rafael; Torres, Javier; Lallena, Antonio M

60 Co sources have been commercialized as an alternative to 192 Ir sources for high-dose-rate (HDR) brachytherapy. One of them is the Flexisource Co-60 HDR source manufactured by Elekta. The only available dosimetric characterization of this source is that of Vijande et al. [J Contemp Brachytherapy 2012; 4:34-44], whose results were not included in the AAPM/ESTRO consensus document. In that work, the dosimetric quantities were calculated as averages of the results obtained with the Geant4 and PENELOPE Monte Carlo (MC) codes, though for other sources, significant differences have been quoted between the values obtained with these two codes. The aim of this work is to perform the dosimetric characterization of the Flexisource Co-60 HDR source using PENELOPE. The MC simulation code PENELOPE (v. 2014) has been used. Following the recommendations of the AAPM/ESTRO report, the radial dose function, the anisotropy function, the air-kerma strength, the dose rate constant, and the absorbed dose rate in water have been calculated. The results we have obtained exceed those of Vijande et al. In particular, the absorbed dose rate constant is ∼0.85% larger. A similar difference is also found in the other dosimetric quantities. The effect of the electrons emitted in the decay of 60 Co, usually neglected in this kind of simulations, is significant up to the distances of 0.25 cm from the source. The systematic and significant differences we have found between PENELOPE results and the average values found by Vijande et al. point out that the dosimetric characterizations carried out with the various MC codes should be provided independently. Copyright © 2017 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.

Evaluation of computer-aided detection and diagnosis systems.

PubMed

Petrick, Nicholas; Sahiner, Berkman; Armato, Samuel G; Bert, Alberto; Correale, Loredana; Delsanto, Silvia; Freedman, Matthew T; Fryd, David; Gur, David; Hadjiiski, Lubomir; Huo, Zhimin; Jiang, Yulei; Morra, Lia; Paquerault, Sophie; Raykar, Vikas; Samuelson, Frank; Summers, Ronald M; Tourassi, Georgia; Yoshida, Hiroyuki; Zheng, Bin; Zhou, Chuan; Chan, Heang-Ping

2013-08-01

Computer-aided detection and diagnosis (CAD) systems are increasingly being used as an aid by clinicians for detection and interpretation of diseases. Computer-aided detection systems mark regions of an image that may reveal specific abnormalities and are used to alert clinicians to these regions during image interpretation. Computer-aided diagnosis systems provide an assessment of a disease using image-based information alone or in combination with other relevant diagnostic data and are used by clinicians as a decision support in developing their diagnoses. While CAD systems are commercially available, standardized approaches for evaluating and reporting their performance have not yet been fully formalized in the literature or in a standardization effort. This deficiency has led to difficulty in the comparison of CAD devices and in understanding how the reported performance might translate into clinical practice. To address these important issues, the American Association of Physicists in Medicine (AAPM) formed the Computer Aided Detection in Diagnostic Imaging Subcommittee (CADSC), in part, to develop recommendations on approaches for assessing CAD system performance. The purpose of this paper is to convey the opinions of the AAPM CADSC members and to stimulate the development of consensus approaches and "best practices" for evaluating CAD systems. Both the assessment of a standalone CAD system and the evaluation of the impact of CAD on end-users are discussed. It is hoped that awareness of these important evaluation elements and the CADSC recommendations will lead to further development of structured guidelines for CAD performance assessment. Proper assessment of CAD system performance is expected to increase the understanding of a CAD system's effectiveness and limitations, which is expected to stimulate further research and development efforts on CAD technologies, reduce problems due to improper use, and eventually improve the utility and efficacy of CAD in clinical practice.

SU-E-T-348: Verification MU Calculation for Conformal Radiotherapy with Multileaf Collimator Using Report AAPM TG 114

DOE Office of Scientific and Technical Information (OSTI.GOV)

Adrada, A; Tello, Z; Medina, L

Purpose: The purpose of this work was to develop and validate an open source independent MU dose calculation software for 3D conformal radiotherapy with multileaf high and low resolution according to the report of AAPM TG 11 Methods: Treatment plans were done using Iplan v4.5 BrainLAB TPS. A 6MV photon beam produced by Primus and Novalis linear accelerators equipped with an Optifocus MLC and HDMLC, respectively. TPS dose calculation algorithms were pencil beam and Monte Carlo. 1082 treatments plans were selected for the study. The algorithm was written in free and open source CodeBlocks C++ platform. Treatment plans were importedmore » by the software using RTP format. Equivalent size field is obtained from the positions of the leaves; the effective depth of calculation can be introduced by TPS's dosimetry report or automatically calculated starting from SSD. The inverse square law is calculated by the 3D coordinates of the isocenter and normalization point of the treatment plan. The dosimetric parameters TPR, Sc, Sp and WF are linearly interpolated. Results: 1082 plans of both machines were analyzed. The average uncertainty between the TPS and the independent calculation was −0.43% ± 2.42% [−7.90%, 7.50%]. Specifically for the Primus the variation obtained was −0.85% ± 2.53% and for the Novalis 0.00% ± 2.23%. Data show that 94.8% of the cases the uncertainty was less than or equal to 5%, while 98.9% is less than or equal to 6%. Conclusion: The developed software is appropriate for use in calculation of UM. This software can be obtained upon request.« less

Praseodymium-142 glass seeds for the brachytherapy of prostate cancer

NASA Astrophysics Data System (ADS)

Jung, Jae Won

A beta-emitting glass seed was proposed for the brachytherapy treatment of prostate cancer. Criteria for seed design were derived and several beta-emitting nuclides were examined for suitability. 142Pr was selected as the isotope of choice. Seeds 0.08 cm in diameter and 0.9 cm long were manufactured for testing. The seeds were activated in the Texas A&M University research reactor. The activity produced was as expected when considering the meta-stable state and epi-thermal neutron flux. The MCNP5 Monte Carlo code was used to calculate the quantitative dosimetric parameters suggested in the American Association of Physicists in Medicine (AAPM) TG-43/60. The Monte Carlo calculation results were compared with those from a dose point kernel code. The dose profiles agree well with each other. The gamma dose of 142Pr was evaluated. The gamma dose is 0.3 Gy at 1.0 cm with initial activity of 5.95 mCi and is insignificant to other organs. Measurements were performed to assess the 2-dimensional axial dose distributions using Gafchromic radiochromic film. The radiochromic film was calibrated using an X-ray machine calibrated against a National Institute of Standards and Technology (NIST) traceable ion chamber. A calibration curve was derived using a least squares fit of a second order polynomial. The measured dose distribution agrees well with results from the Monte Carlo simulation. The dose was 130.8 Gy at 6 mm from the seed center with initial activity of 5.95 mCi. AAPM TG-43/60 parameters were determined. The reference dose rate for 2 mm and 6 mm were 0.67 and 0.02 cGy/s/mCi, respectively. The geometry function, radial dose function and anisotropy function were generated.

SU-E-E-01: ABR Diagnostic Radiology Core Exam: Was Our Redesigned Physics Course Successful in Teaching Physics to Radiology Residents?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kanal, K; Hoff, M; Dickinson, R

Purpose: Our purpose is to evaluate the effectiveness of our two year physics course in preparing radiology residents for the American Board of Radiology (ABR) diagnostic radiology exam. Methods: We designed a new two-year physics course that integrates radiology clinical content and practice and is primarily based on the AAPM curriculum and RSNA/AAPM physics modules. Biweekly classes focus on relevant concepts from assigned reading and use audience response systems to encourage participation. Teaching efficiency is optimized through lecturer rotations of physicists, radiologists, and guest speakers. An emphasis is placed on clinical relevance by requiring lab work and providing equipment demonstrations.more » Periodic quiz were given during the course. The course website was also redesigned for usability, and physics review lectures were conducted two weeks before the board exam to refresh key concepts. At the completion of our first two-year course, we conducted a confidential evaluation of the faculty and course. The evaluation assessed metrics such as overall organization, clinical relevance of content, and level of difficulty, with a rating scale from poor to excellent. Results: Our evaluation indicated that the redesigned course provided effective board exam preparation, with most responses between good and excellent. There was some criticism on the course length and on chronological discontinuity, but the review lectures were appreciated by the residents. All of our residents passed the physics component of the ABR exam with scores exceeding the minimum passing score by a significant margin. Conclusion: The course evaluation and board exam results indicate that our new two-year course format provides valuable board exam preparation. This is possible thanks to the time and effort taken by the physics faculty on ensuring the residents get quality physics education.« less

MO-E-BRE-01: Determination, Minimization and Communication of Uncertainties in Radiation Therapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Van Dyk, J; Palta, J; Bortfeld, T

2014-06-15

Medical Physicists have a general understanding of uncertainties in the radiation treatment process, both with respect to dosimetry and geometry. However, there is a desire to be more quantitative about uncertainty estimation. A recent International Atomic Energy Agency (IAEA) report (about to be published) recommends that we should be as “accurate as reasonably achievable, technical and biological factors being taken into account”. Thus, a single recommendation as a goal for accuracy in radiation therapy is an oversimplification. That report also suggests that individual clinics should determine their own level of uncertainties for their specific treatment protocols. The question is “howmore » do we implement this in clinical practice”? AAPM Monograph 35 (2011 AAPM Summer School) addressed many specific aspects of uncertainties in each of the steps of a course of radiation treatment. The intent of this symposium is: (1) to review uncertainty considerations in the entire radiation treatment process including uncertainty determination for each step and uncertainty propagation for the total process, (2) to consider aspects of robust optimization which optimizes treatment plans while protecting them against uncertainties, and (3) to describe various methods of displaying uncertainties and communicating uncertainties to the relevant professionals. While the theoretical and research aspects will also be described, the emphasis will be on the practical considerations for the medical physicist in clinical practice. Learning Objectives: To review uncertainty determination in the overall radiation treatment process. To consider uncertainty modeling and uncertainty propagation. To highlight the basic ideas and clinical potential of robust optimization procedures to generate optimal treatment plans that are not severely affected by uncertainties. To describe methods of uncertainty communication and display.« less

Evaluation of computer-aided detection and diagnosis systemsa)

PubMed Central

Petrick, Nicholas; Sahiner, Berkman; Armato, Samuel G.; Bert, Alberto; Correale, Loredana; Delsanto, Silvia; Freedman, Matthew T.; Fryd, David; Gur, David; Hadjiiski, Lubomir; Huo, Zhimin; Jiang, Yulei; Morra, Lia; Paquerault, Sophie; Raykar, Vikas; Samuelson, Frank; Summers, Ronald M.; Tourassi, Georgia; Yoshida, Hiroyuki; Zheng, Bin; Zhou, Chuan; Chan, Heang-Ping

2013-01-01

Computer-aided detection and diagnosis (CAD) systems are increasingly being used as an aid by clinicians for detection and interpretation of diseases. Computer-aided detection systems mark regions of an image that may reveal specific abnormalities and are used to alert clinicians to these regions during image interpretation. Computer-aided diagnosis systems provide an assessment of a disease using image-based information alone or in combination with other relevant diagnostic data and are used by clinicians as a decision support in developing their diagnoses. While CAD systems are commercially available, standardized approaches for evaluating and reporting their performance have not yet been fully formalized in the literature or in a standardization effort. This deficiency has led to difficulty in the comparison of CAD devices and in understanding how the reported performance might translate into clinical practice. To address these important issues, the American Association of Physicists in Medicine (AAPM) formed the Computer Aided Detection in Diagnostic Imaging Subcommittee (CADSC), in part, to develop recommendations on approaches for assessing CAD system performance. The purpose of this paper is to convey the opinions of the AAPM CADSC members and to stimulate the development of consensus approaches and “best practices” for evaluating CAD systems. Both the assessment of a standalone CAD system and the evaluation of the impact of CAD on end-users are discussed. It is hoped that awareness of these important evaluation elements and the CADSC recommendations will lead to further development of structured guidelines for CAD performance assessment. Proper assessment of CAD system performance is expected to increase the understanding of a CAD system's effectiveness and limitations, which is expected to stimulate further research and development efforts on CAD technologies, reduce problems due to improper use, and eventually improve the utility and efficacy of CAD in clinical practice. PMID:23927365

Evolving models for medical physics education and training: a global perspective.

PubMed

Sprawls, P

2008-01-01

There is a significant need for high-quality medical physics education and training in all countries to support effective and safe use of modern medical technology for both diagnostic and treatment purposes. This is, and will continue to be, achieved using appropriate technology to increase both the effectiveness and efficiency of educational activities everywhere in the world. While the applications of technology to education and training are relatively new, the successful applications are based on theories and principles of the learning process developed by two pioneers in the field, Robert Gagne and Edgar Dale.The work of Gagne defines the different levels of learning that can occur and is used to show the types and levels of learning that are required for the application of physics and engineering principles to achieve appropriate diagnostic and therapeutic results from modern technology. The learning outcomes are determined by the effectiveness of the learning activity or experience. The extensive work of Dale as formulated in his Cone of Experience relates the effectiveness to the efficiency of educational activities. A major challenge in education is the development and conduction of learning activities (classroom discussions, laboratory and applied experiences, individual study, etc) that provide an optimum balance between effectiveness and efficiency. New and evolving models of the educational process use technology as the infrastructure to support education that is both more effective and efficient.The goal is to use technology to enhance human performance for both learners (students) and learning facilitators (teachers). A major contribution to global education is the trend in the development of shared educational resources. Two models of programs to support this effort with open and free shared resources are Physical Principles of Medical Imaging Online (http://www.sprawls.org/resources) and AAPM Continuing Education Courses (http://www.aapm.org/international).

Evolving models for medical physics education and training: a global perspective

PubMed Central

Sprawls, P

2008-01-01

There is a significant need for high-quality medical physics education and training in all countries to support effective and safe use of modern medical technology for both diagnostic and treatment purposes. This is, and will continue to be, achieved using appropriate technology to increase both the effectiveness and efficiency of educational activities everywhere in the world. While the applications of technology to education and training are relatively new, the successful applications are based on theories and principles of the learning process developed by two pioneers in the field, Robert Gagne and Edgar Dale. The work of Gagne defines the different levels of learning that can occur and is used to show the types and levels of learning that are required for the application of physics and engineering principles to achieve appropriate diagnostic and therapeutic results from modern technology. The learning outcomes are determined by the effectiveness of the learning activity or experience. The extensive work of Dale as formulated in his Cone of Experience relates the effectiveness to the efficiency of educational activities. A major challenge in education is the development and conduction of learning activities (classroom discussions, laboratory and applied experiences, individual study, etc) that provide an optimum balance between effectiveness and efficiency. New and evolving models of the educational process use technology as the infrastructure to support education that is both more effective and efficient. The goal is to use technology to enhance human performance for both learners (students) and learning facilitators (teachers). A major contribution to global education is the trend in the development of shared educational resources. Two models of programs to support this effort with open and free shared resources are Physical Principles of Medical Imaging Online (http://www.sprawls.org/resources) and AAPM Continuing Education Courses (http://www.aapm.org/international). PMID:21614309

Vocal Control: Is It Susceptible to the Negative Effects of Self-Regulatory Depletion?

PubMed

Vinney, Lisa A; van Mersbergen, Miriam; Connor, Nadine P; Turkstra, Lyn S

2016-09-01

Self-regulation (SR) relies on the capacity to modify behavior. This capacity may diminish with use and result in self-regulatory depletion (SRD), or the reduced ability to engage in future SR efforts. If the SRD effect applies to vocal behavior, it may hinder success during behavioral voice treatment. Thus, this proof-of-concept study sought to determine whether SRD affects vocal behavior change and if so, whether it can be repaired by an intervention meant to replete SR resources. One hundred four women without voice disorders were randomized into groups that performed either (1) a high-SR writing task followed by a high-SR voice task; (2) a low-SR writing task followed by a high-SR voice task; or (3) a high-SR writing task followed by a relaxation intervention and a high-SR voice task. The high-SR voice tasks in all groups involved suppression of the Lombard effect during reading and free speech. The low-SR group suppressed the Lombard effect to a greater extent than the high-SR group and high-SR-plus-relaxation group on the free speech task. There were no significant group differences on the reading task. Findings suggest that SRD may present challenges to vocal behavior modification during free speech but not reading. Furthermore, relaxation did not significantly replete self-regulatory resources for vocal modification during free speech. Findings may highlight potential considerations for voice treatment and assessment and support the need for future research focusing on effective methods to test self-regulatory capacity and replete self-regulatory resources in voice patients. Published by Elsevier Inc.

The Independence and Interdependence of Coacting Observers in Regard to Performance Efficiency, Workload, and Stress in a Vigilance Task.

PubMed

Funke, Gregory J; Warm, Joel S; Baldwin, Carryl L; Garcia, Andre; Funke, Matthew E; Dillard, Michael B; Finomore, Victor S; Matthews, Gerald; Greenlee, Eric T

2016-09-01

We investigated performance, workload, and stress in groups of paired observers who performed a vigilance task in a coactive (independent) manner. Previous studies have demonstrated that groups of coactive observers detect more signals in a vigilance task than observers working alone. Therefore, the use of such groups might be effective in enhancing signal detection in operational situations. However, concern over appearing less competent than one's cohort might induce elevated levels of workload and stress in coactive group members and thereby undermine group performance benefits. Accordingly, we performed the initial experiment comparing workload and stress in observers who performed a vigilance task coactively with those of observers who performed the vigilance task alone. Observers monitored a video display for collision flight paths in a simulated unmanned aerial vehicle control task. Self-reports of workload and stress were secured via the NASA-Task Load Index and the Dundee Stress State Questionnaire, respectively. Groups of coactive observers detected significantly more signals than did single observers. Coacting observers did not differ significantly from those operating by themselves in terms of workload but did in regard to stress; posttask distress was significantly lower for coacting than for single observers. Performing a visual vigilance task in a coactive manner with another observer does not elevate workload above that of observers working alone and serves to attenuate the stress associated with vigilance task performance. The use of coacting observers could be an effective vehicle for enhancing performance efficiency in operational vigilance. © 2016, Human Factors and Ergonomics Society.

The Impact of Communication Mode and Task Complexity on Small Group Performance and Member Satisfaction.

ERIC Educational Resources Information Center

Carey, Jane M.; Kacmar, Charles, J.

1997-01-01

It is often presumed that software technology will increase group productivity, but this may not be the case. Examines the impact of technology on time-to-complete-task, member satisfaction, perceived information load, number of contributing transactions, and task complexity. Three appendices provide examples of complex and simple tasks and the…

Amnestic mild cognitive impairment: functional MR imaging study of response in posterior cingulate cortex and adjacent precuneus during problem-solving tasks.

PubMed

Jin, Guangwei; Li, Kuncheng; Hu, Yingying; Qin, Yulin; Wang, Xiangqing; Xiang, Jie; Yang, Yanhui; Lu, Jie; Zhong, Ning

2011-11-01

To compare the blood oxygen level-dependent (BOLD) response, measured with functional magnetic resonance (MR) imaging, in the posterior cingulate cortex (PCC) and adjacent precuneus regions between healthy control subjects and patients with amnestic mild cognitive impairment (MCI) during problem-solving tasks. This study was approved by the institutional review board. Each subject provided written informed consent. Thirteen patients with amnestic MCI and 13 age- and sex-matched healthy control subjects participated in the study. The functional magnetic resonance (MR) imaging tasks were simplified 4 × 4-grid number placement puzzles that were divided into a simple task (using the row rule or the column rule to solve the puzzle) and a complex task (using both the row and column rules to solve the puzzle). Behavioral results and functional imaging results between the healthy control group and the amnestic MCI group were analyzed. The accuracy for the complex task in the healthy control group was significantly higher than that in the amnestic MCI group (P < .05). The healthy control group exhibited a deactivated BOLD signal intensity (SI) change in the bilateral PCC and adjacent precuneus regions during the complex task, whereas the amnestic MCI group showed activation. The positive linear correlations between the BOLD SI change in bilateral PCC and adjacent precuneus regions and in bilateral hippocampi in the amnestic MCI group were significant (P < .001), while in the healthy control group, they were not (P ≥ .23). These findings suggest that an altered BOLD response in amnestic MCI patients during complex tasks might be related to a decline in problem-solving ability and to memory impairment and, thus, may indicate a compensatory response to memory impairment. RSNA, 2011

SU-F-E-18: Training Monthly QA of Medical Accelerators: Illustrated Instructions for Self-Learning

DOE Office of Scientific and Technical Information (OSTI.GOV)

Court, L; Wang, H; Aten, D

Purpose: To develop and test clear illustrated instructions for training of monthly mechanical QA of medical linear accelerators. Methods: Illustrated instructions were created for monthly mechanical QA with tolerance tabulated, and underwent several steps of review and refinement. Testers with zero QA experience were then recruited from our radiotherapy department (1 student, 2 computational scientists and 8 dosimetrists). The following parameters were progressively de-calibrated on a Varian C-series linac: Group A = gantry angle, ceiling laser position, X1 jaw position, couch longitudinal position, physical graticule position (5 testers); Group B = Group A + wall laser position, couch lateral andmore » vertical position, collimator angle (3 testers); Group C = Group B + couch angle, wall laser angle, and optical distance indicator (3 testers). Testers were taught how to use the linac, and then used the instructions to try to identify these errors. A physicist observed each session, giving support on machine operation, as necessary. The instructions were further tested with groups of therapists, graduate students and physics residents at multiple institutions. We have also changed the language of the instructions to simulate using the instructions with non-English speakers. Results: Testers were able to follow the instructions. They determined gantry, collimator and couch angle errors within 0.4, 0.3, and 0.9degrees of the actual changed values, respectively. Laser positions were determined within 1mm, and jaw positions within 2mm. Couch position errors were determined within 2 and 3mm for lateral/longitudinal and vertical errors, respectively. Accessory positioning errors were determined within 1mm. ODI errors were determined within 2mm when comparing with distance sticks, and 6mm when using blocks, indicating that distance sticks should be the preferred approach for inexperienced staff. Conclusion: Inexperienced users were able to follow these instructions, and catch errors within the criteria suggested by AAPM TG142 for linacs used for IMRT.« less

Language and theory of mind in autism spectrum disorder: the relationship between complement syntax and false belief task performance.

PubMed

Lind, Sophie E; Bowler, Dermot M

2009-06-01

This study aimed to test the hypothesis that children with autism spectrum disorder (ASD) use their knowledge of complement syntax as a means of "hacking out" solutions to false belief tasks, despite lacking a representational theory of mind (ToM). Participants completed a "memory for complements" task, a measure of receptive vocabulary, and traditional location change and unexpected contents false belief tasks. Consistent with predictions, the correlation between complement syntax score and location change task performance was significantly stronger within the ASD group than within the comparison group. However, contrary to predictions, complement syntax score was not significantly correlated with unexpected contents task performance within either group. Possible explanations for this pattern of results are considered.

An effective repetitive training schedule to achieve skill proficiency using a novel robotic virtual reality simulator.

PubMed

Kang, Sung Gu; Ryu, Byung Ju; Yang, Kyung Sook; Ko, Young Hwii; Cho, Seok; Kang, Seok Ho; Patel, Vipul R; Cheon, Jun

2015-01-01

A robotic virtual reality simulator (Mimic dV-Trainer) can be a useful training method for the da Vinci surgical system. Herein, we investigate several repetitive training schedules and determine which is the most effective. A total of 30 medical students were enrolled and were divided into 3 groups according to the training schedule. Group 1 performed the task 1 hour daily for 4 consecutive days, group II performed the task on once per week for 1 hour for 4 consecutive weeks, and group III performed the task for 4 consecutive hours in 1 day. The effects of training were investigated by analyzing the number of repetitions and the time required to complete the "Tube 2" simulation task when the learning curve plateau was reached. The point at which participants reached a stable score was evaluated using the cumulative sum control graph. The average time to complete the task at the learning curve plateau was 150.3 seconds in group I, 171.9 seconds in group II, and 188.5 seconds in group III. The number of task repetitions required to reach the learning curve plateau was 45 repetitions in group I, 36 repetitions in group II, and 39 repetitions in group III. Therefore, there was continuous improvement in the time required to perform the task after 40 repetitions in group I only. There was a significant correlation between improvement in each trial interval and attempt, and the correlation coefficient (0.924) in group I was higher than that in group II (0.899) and group III (0.838). Daily 1-hour practice sessions performed for 4 consecutive days resulted in the best final score, continuous score improvement, and effective training while minimizing fatigue. This repetition schedule can be used for effectively training novices in future. Copyright © 2015 Association of Program Directors in Surgery. Published by Elsevier Inc. All rights reserved.

The work of the ICRP dose calculational task group: Issues in implementation of the ICRP dosimetric methodology

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eckerman, K.F.

Committee 2 of the International Commission on Radiological Protection (ICRP) has had efforts underway to provide the radiation protection community with age-dependent dose coefficients, i.e.g, the dose per unit intake. The Task Group on Dose Calculations, chaired by the author, is responsible for the computation of these coefficients. The Task Group, formed in 1974 to produce ICRP Publication 30, is now international in its membership and its work load has been distributed among the institutions represented on the task group. This paper discusses: (1) recent advances in biokinetic modeling; (2) the recent changes in the dosimetric methodology; (3) the novelmore » computational problems with some of the ICRP quantities; and (4) quality assurance issues which the Task Group has encountered. Potential future developments of the dosimetric framework which might strengthen the relationships with the emerging understanding of radiation risk will also be discussed.« less

Can Dual Task Walking Improve in Parkinson's Disease After External Focus of Attention Exercise? A Single Blind Randomized Controlled Trial.

PubMed

Beck, Eric N; Intzandt, Brittany N; Almeida, Quincy J

2018-01-01

It may be possible to use attention-based exercise to decrease demands associated with walking in Parkinson's disease (PD), and thus improve dual task walking ability. For example, an external focus of attention (focusing on the effect of an action on the environment) may recruit automatic control processes degenerated in PD, whereas an internal focus (limb movement) may recruit conscious (nonautomatic) control processes. Thus, we aimed to investigate how externally and internally focused exercise influences dual task walking and symptom severity in PD. Forty-seven participants with PD were randomized to either an Externally (n = 24) or Internally (n = 23) focused group and completed 33 one-hour attention-based exercise sessions over 11 weeks. In addition, 16 participants were part of a control group. Before, after, and 8 weeks following the program (pre/post/washout), gait patterns were measured during single and dual task walking (digit-monitoring task, ie, walking while counting numbers announced by an audio-track), and symptom severity (UPDRS-III) was assessed ON and OFF dopamine replacement. Pairwise comparisons (95% confidence intervals [CIs]) and repeated-measures analyses of variance were conducted. Pre to post: Dual task step time decreased in the external group (Δ = 0.02 seconds, CI 0.01-0.04). Dual task step length (Δ = 2.3 cm, CI 0.86-3.75) and velocity (Δ = 4.5 cm/s, CI 0.59-8.48) decreased (became worse) in the internal group. UPDRS-III scores (ON and OFF) decreased (improved) in only the External group. Pre to washout: Dual task step time ( P = .005) and percentage in double support ( P = .014) significantly decreased (improved) in both exercise groups, although only the internal group increased error on the secondary counting task (ie, more errors monitoring numbers). UPDRS-III scores in both exercise groups significantly decreased ( P = .001). Since dual task walking improvements were found immediately, and 8 weeks after the cessation of an externally focused exercise program, we conclude that externally focused exercise may improve on functioning of automatic control networks in PD. Internally focused exercise hindered dual tasking ability. Overall, externally focused exercise led to greater rehabilitation benefits in dual tasking and motor symptoms compared with internally focused exercise.

Mechanical evaluation of articulating instruments and cross-handed manipulation in laparoendoscopic single-site surgery.

PubMed

Xu, An An; Zhu, Jiang Fan; Xie, Xiaofeng; Su, Yuantao

2014-08-01

Laparoendoscopic single-site surgery (LESS) is limited by loss of triangulation and internal instruments conflict. To overcome these difficulties, some concepts have been introduced, namely, articulating instruments and cross-handed manipulation, which causes the right hand to control the left instrument tip and vice versa. The aim of this study was to compare task performance with different approaches based on a mechanical evaluation platform. A LESS mechanical evaluation platform was set up to investigate the performance of 2 tasks (suture pass-through rings and clip-cut) with 3 different settings: uncrossed manipulation with straight instruments (group A, the control group), uncrossed manipulation with articulating instruments (group B), and cross-handed manipulation with articulating instruments (group C). The operation time and average load required for accomplishment of the standard tasks were measured. Group A presented significantly better time scores than group B, and group C consumed the longest time to accomplish the 2 tasks (P < .05). Comparing of average load required to perform the suture pass-through rings task, it differed significantly between dominant and nondominant hand in all groups (P < .01) and was less in group A and group B than group C in dominant hand (P < .01), while it was almost the same in all groups in the nondominant hand. In terms of average load requirement to accomplish clip-cut task, it was almost equal not only between group A and B but also between dominant and nondominant hand while the increase reached statistical significance when comparing group C with other groups (P < .05). Compared with conventional devices and maneuvering techniques, articulating instruments and cross-handed manipulation are associated with longer operation time and higher workload. Instruments with better maneuverability should be developed in the future for LESS. © The Author(s) 2013.

Numerical processing efficiency improved in children using mental abacus: ERP evidence utilizing a numerical Stroop task

PubMed Central

Yao, Yuan; Du, Fenglei; Wang, Chunjie; Liu, Yuqiu; Weng, Jian; Chen, Feiyan

2015-01-01

This study examined whether long-term abacus-based mental calculation (AMC) training improved numerical processing efficiency and at what stage of information processing the effect appeard. Thirty-three children participated in the study and were randomly assigned to two groups at primary school entry, matched for age, gender and IQ. All children went through the same curriculum except that the abacus group received a 2-h/per week AMC training, while the control group did traditional numerical practice for a similar amount of time. After a 2-year training, they were tested with a numerical Stroop task. Electroencephalographic (EEG) and event related potential (ERP) recording techniques were used to monitor the temporal dynamics during the task. Children were required to determine the numerical magnitude (NC) (NC task) or the physical size (PC task) of two numbers presented simultaneously. In the NC task, the AMC group showed faster response times but similar accuracy compared to the control group. In the PC task, the two groups exhibited the same speed and accuracy. The saliency of numerical information relative to physical information was greater in AMC group. With regards to ERP results, the AMC group displayed congruity effects both in the earlier (N1) and later (N2 and LPC (late positive component) time domain, while the control group only displayed congruity effects for LPC. In the left parietal region, LPC amplitudes were larger for the AMC than the control group. Individual differences for LPC amplitudes over left parietal area showed a positive correlation with RTs in the NC task in both congruent and neutral conditions. After controlling for the N2 amplitude, this correlation also became significant in the incongruent condition. Our results suggest that AMC training can strengthen the relationship between symbolic representation and numerical magnitude so that numerical information processing becomes quicker and automatic in AMC children. PMID:26042012

Brain activity in adults who stutter: Similarities across speaking tasks and correlations with stuttering frequency and speaking rate

PubMed Central

Ingham, Roger J.; Grafton, Scott T.; Bothe, Anne K.; Ingham, Janis C.

2012-01-01

Many differences in brain activity have been reported between persons who stutter (PWS) and typically fluent controls during oral reading tasks. An earlier meta-analysis of imaging studies identified stutter-related regions, but recent studies report less agreement with those regions. A PET study on adult dextral PWS (n = 18) and matched fluent controls (CONT, n = 12) is reported that used both oral reading and monologue tasks. After correcting for speech rate differences between the groups the task-activation differences were surprisingly small. For both analyses only some regions previously considered stutter-related were more activated in the PWS group than in the CONT group, and these were also activated during eyes-closed rest (ECR). In the PWS group, stuttering frequency was correlated with cortico-striatal-thalamic circuit activity in both speaking tasks. The neuroimaging findings for the PWS group, relative to the CONT group, appear consistent with neuroanatomic abnormalities being increasingly reported among PWS. PMID:22564749

The effect of motivation and positive affect on ego depletion: Replenishment versus release mechanism.

PubMed

Zhu, Ze; Li, Jian; Zhang, Bo; Li, Ye; Zhang, Houcan

2017-12-01

In this study, 2 experiments were conducted to investigate whether motivation and positive affect can alleviate ego depletion and to elucidate their possible mechanisms. In Experiment 1, a crossing-out-letter task was adapted to reach an ego depletion state for Chinese participants. Participants were then randomly assigned to the extrinsic motivation group, the positive affect group or the depletion control group. After the experimental treatment, a dumbbell task was used to measure participants' remaining self-regulatory resources. The results showed that participants in the motivation and positive affect groups performed better on the dumbbell task than participants in the depletion control group. Experiment 2 was similar to Experiment 1 except that participants were asked to perform an additional unexpected dumbbell task after a neutral video following the above procedure. The results of Experiment 1 were replicated; however, participants' performance on the additional dumbbell task differed. The positive affect group performed better than the depletion control group, indicating an increase in self-regulatory resources and thus supporting the replenishment effect of positive affect. No significant difference was found between the motivation group and the depletion control group. © 2015 International Union of Psychological Science.

Are There Detrimental Effects From Proficiency-Based Training in Fundamentals of Laparoscopic Surgery Among Novices? An Exploration of Goal Theory.

PubMed

Stoller, Jeremy; Joseph, Jeremy; Parodi, Nicholas; Gardner, Aimee

2016-01-01

Goal theory states that novices may experience unintended, detrimental learning effects, with decreased performance, when given performance goals on complex tasks. In these situations, it may be more appropriate to give novices learning goals to help avoid these negative consequences. The purpose of this study was to see whether this tenant of goal theory applied to novices learning 2 tasks of fundamentals of laparoscopic surgery (FLS). Medical and physician assistant students were randomized to a performance goals group and a learning goals group. The performance goals consisted of the published proficiency standards of FLS. Both groups were pretested on perception of surgery, self-efficacy, and general affect. Each group underwent a practice session for the peg transfer task. They were tested and scored per the published standards of FLS. The participants completed NASA Task Load Index, task complexity, and postaffect questionnaires related to the peg transfer task. This was repeated with the suture with intracorporeal knot task. Posttest perception of surgery and self-efficacy questionnaires were completed. In total, 48 students participated in the study: 23 in the performance goals group and 25 in the learning goals group. Most of the participants (n = 40) were first-year medical and physician assistant students. There were no significant differences between the groups in perception of surgery, affect, goal commitment, subjective task complexity, subjective workload, and self-efficacy. There were no differences between the groups concerning overall FLS score for both the peg transfer and suturing tasks. Both groups exhibited significant increases in self-efficacy and perception of surgery (p < 0.05). FLS skills can be given to novice learners without concern for detrimental effects as might be expected by other work on goal theory. Given that performance was the same for both groups, surgical educators may have multiple pathways to educational success when incorporating goals into training programs for basic surgical skills. Copyright © 2015 Association of Program Directors in Surgery. Published by Elsevier Inc. All rights reserved.

Failure at the top: How power undermines collaborative performance.

PubMed

Hildreth, John Angus D; Anderson, Cameron

2016-02-01

All too commonly, we see groups of leaders fail to accomplish their stated goals when working together--legislators who cannot agree on a bill, heads of state who cannot draft meaningful environmental policy, or boards of trustees who make disastrous decisions for their school. The current research examines whether groups of leaders fail as often as they do in part because of the power each leader is accustomed to possessing among his or her constituents. In multiple studies we found that high power individuals, when working together in groups, performed worse than did other groups: individuals randomly assigned power in an initial task were less creative when they then worked together in groups on a subsequent task (Studies 1A and 4). Individuals with higher power who worked together in groups were also less likely to reach agreement on a difficult negotiation task, whether these groups comprised actual executives from an extant organization (Study 2) or participants randomly assigned power in the laboratory (Study 3). Mediation analyses suggest that groups of high power individuals performed worse because they fought over their relative status in the group, were less focused on the task, and shared information with each other less effectively. However, high power individuals were more effective when working on tasks that required less coordination: they were more creative (Studies 1B and 4) and persisted longer on a difficult task than other groups. Therefore, group processes are the key problem for groups of high power individuals when they work together. (c) 2016 APA, all rights reserved).

Reliability of drivers in urban intersections.

PubMed

Gstalter, Herbert; Fastenmeier, Wolfgang

2010-01-01

The concept of human reliability has been widely used in industrial settings by human factors experts to optimise the person-task fit. Reliability is estimated by the probability that a task will successfully be completed by personnel in a given stage of system operation. Human Reliability Analysis (HRA) is a technique used to calculate human error probabilities as the ratio of errors committed to the number of opportunities for that error. To transfer this notion to the measurement of car driver reliability the following components are necessary: a taxonomy of driving tasks, a definition of correct behaviour in each of these tasks, a list of errors as deviations from the correct actions and an adequate observation method to register errors and opportunities for these errors. Use of the SAFE-task analysis procedure recently made it possible to derive driver errors directly from the normative analysis of behavioural requirements. Driver reliability estimates could be used to compare groups of tasks (e.g. different types of intersections with their respective regulations) as well as groups of drivers' or individual drivers' aptitudes. This approach was tested in a field study with 62 drivers of different age groups. The subjects drove an instrumented car and had to complete an urban test route, the main features of which were 18 intersections representing six different driving tasks. The subjects were accompanied by two trained observers who recorded driver errors using standardized observation sheets. Results indicate that error indices often vary between both the age group of drivers and the type of driving task. The highest error indices occurred in the non-signalised intersection tasks and the roundabout, which exactly equals the corresponding ratings of task complexity from the SAFE analysis. A comparison of age groups clearly shows the disadvantage of older drivers, whose error indices in nearly all tasks are significantly higher than those of the other groups. The vast majority of these errors could be explained by high task load in the intersections, as they represent difficult tasks. The discussion shows how reliability estimates can be used in a constructive way to propose changes in car design, intersection layout and regulation as well as driver training.

77 FR 77046 - Defense Business Board; Notice of Federal Advisory Committee Meeting

Federal Register 2010, 2011, 2012, 2013, 2014

2012-12-31

... ``Employing Our Veterans Part II: Review of Pilot Transition Goal Plans Success Program'' Task Group Studies.... Availability of Materials for the Meeting: A copy of the agenda and the terms of reference for the Task Group... also be available at the meeting. Meeting Agenda 9:15 a.m.--11:30 a.m. Task Group Outbrief and Board...

Effects of reading-oriented tasks on students' reading comprehension of geometry proof

NASA Astrophysics Data System (ADS)

Yang, Kai-Lin; Lin, Fou-Lai

2012-06-01

This study compared the effects of reading-oriented tasks and writing-oriented tasks on students' reading comprehension of geometry proof (RCGP). The reading-oriented tasks were designed with reading strategies and the idea of problem posing. The writing-oriented tasks were consistent with usual proof instruction for writing a proof and applying it. Twenty-two classes of ninth-grade students ( N = 683), aged 14 to 15 years, and 12 mathematics teachers participated in this quasi-experimental classroom study. While the experimental group was instructed to read and discuss the reading tasks in two 45-minute lessons, the control group was instructed to prove and apply the same propositions. Generalised estimating equation (GEE) method was used to compare the scores of the post-test and the delayed post-test with the pre-test scores as covariates. Results showed that the total scores of the delayed post-test of the experimental group were significantly higher than those of the control group. Furthermore, the scores of the experimental group on all facets of reading comprehension except the application facet were significantly higher than those of the control group for both the post-test and delayed post-test.

Effects of task-oriented robot training on arm function, activity, and quality of life in chronic stroke patients: a randomized controlled trial.

PubMed

Timmermans, Annick A A; Lemmens, Ryanne J M; Monfrance, Maurice; Geers, Richard P J; Bakx, Wilbert; Smeets, Rob J E M; Seelen, Henk A M

2014-03-31

Over fifty percent of stroke patients experience chronic arm hand performance problems, compromising independence in daily life activities and quality of life. Task-oriented training may improve arm hand performance after stroke, whereby augmented therapy may lead to a better treatment outcome. Technology-supported training holds opportunities for increasing training intensity. However, the effects of robot-supported task-oriented training with real life objects in stroke patients are not known to date. The aim of the present study was to investigate the effectiveness and added value of the Haptic Master robot combined with task-oriented arm hand training in chronic stroke patients. In a single-blind randomized controlled trial, 22 chronic stroke patients were randomly allocated to receive either task-oriented robot-assisted arm-hand training (experimental group) or task-oriented non-robotic arm-hand training (control group). For training, the T-TOAT (Technology-supported Task-Oriented Arm Training) method was applied. Training was provided during 8 weeks, 4 times/week, 2 × 30 min/day. A significant improvement after training on the Action Research Arm Test (ARAT) was demonstrated in the experimental group (p = 0.008). Results were maintained until 6 months after cessation of the training. On the perceived performance measure (Motor Activity Log (MAL)), both, the experimental and control group improved significantly after training (control group p = 0.008; experimental group p = 0.013). The improvements on MAL in both groups were maintained until 6 months after cessation of the training. With regard to quality of life, only in the control group a significant improvement after training was found (EuroQol-5D p = 0.015, SF-36 physical p = 0.01). However, the improvement on SF-36 in the control group was not maintained (p = 0.012). No between-group differences could be demonstrated on any of the outcome measures. Arm hand performance improved in chronic stroke patients, after eight weeks of task oriented training. The use of a Haptic Master robot in support of task-oriented arm training did not show additional value over the video-instructed task-oriented exercises in highly functional stroke patients. Current Controlled Trials ISRCTN82787126.

Short-term effects of using verbal instructions and demonstration at the beginning of learning a complex skill in figure skating.

PubMed

Haguenauer, Marianne; Fargier, Patrick; Legreneur, Pierre; Dufour, Anne-Béatrice; Cogerino, Geneviève; Begon, Mickaël; Monteil, Karine M

2005-02-01

This study examined whether providing verbal instructions plus demonstration and task repetition facilitates the early acquisition of a sport skill for which learners had a prior knowledge of the individual motor components. After one demonstration of the task by an expert, 18 novice skaters practiced a figure skating jump during a 15-min. period. Subjects were randomly assigned to one of 3 groups: a group provided with a verbal instruction that specified the subgoals of the task (Subgoals group), a group provided with a verbal instruction that used a metaphor (Metaphoric group), and a group not receiving any specific instruction during training (Control group). Subjects were filmed prior to and immediately following the practice session. Analysis indicated that the modifications of performance were related to the demonstration and the subsequent task repetitions only. Providing additional verbal instructions generated no effect. Therefore, guiding the learner toward a solution to the task problem by means of verbal instruction seems to be ineffective if done too early in the course of learning.

Memory and subjective workload assessment

NASA Technical Reports Server (NTRS)

Staveland, L.; Hart, S.; Yeh, Y. Y.

1986-01-01

Recent research suggested subjective introspection of workload is not based upon specific retrieval of information from long term memory, and only reflects the average workload that is imposed upon the human operator by a particular task. These findings are based upon global ratings of workload for the overall task, suggesting that subjective ratings are limited in ability to retrieve specific details of a task from long term memory. To clarify the limits memory imposes on subjective workload assessment, the difficulty of task segments was varied and the workload of specified segments was retrospectively rated. The ratings were retrospectively collected on the manipulations of three levels of segment difficulty. Subjects were assigned to one of two memory groups. In the Before group, subjects knew before performing a block of trials which segment to rate. In the After group, subjects did not know which segment to rate until after performing the block of trials. The subjective ratings, RTs (reaction times) and MTs (movement times) were compared within group, and between group differences. Performance measures and subjective evaluations of workload reflected the experimental manipulations. Subjects were sensitive to different difficulty levels, and recalled the average workload of task components. Cueing did not appear to help recall, and memory group differences possibly reflected variations in the groups of subjects, or an additional memory task.

Summary record of presentations to the Federal Telecommunication Standards Committee/Fiber optics task group

NASA Astrophysics Data System (ADS)

Hanson, A. G.

1987-03-01

The learning experience of a group of Federal-agency planners who face upgrading or augmenting existing on-premises communication systems and building wiring is documented. In July 1984, an interagency Fiber Optics Task Group was formed under the aegis of the Federal Telecommunication Standards Committee to study on-premises distribution systems, with emphasis on optical fiber implementation, sharing mutual problems and potential solutions for them. Chronological summary records of technical content of 11 Task Group meetings through September 1986 are summarized. Also condensed are the engineering presentations to the Task Group by industry on applicable state-of-the-art technology, including local area networks, private automatic branch exchanges, building wiring architecture, and optic fiber systems and components.

The effects of priming with age stereotypes on a PC-based mail-sorting task.

PubMed

Kirchner, Christine; Bock, Otmar Leo; Völker, Ina

2017-04-01

This study examines whether unconscious priming of attitudes towards older age might change the self-efficacy of older employees, and thus modify their performance at work. Three age- and gender-matched groups of 20 participants were primed with positive, negative or no age stereotypes by means of the scrambled sentence task, and were then transferred to a cognitively demanding PC-based mail-sorting task. Participants' accuracy on the latter task was significantly higher in the positively primed group than in the unprimed group, and was significantly lower in the negatively primed group than in the unprimed group, except for one parameter. These findings indicate that the performance of older workers may indeed be modifiable by unconscious priming. Practitioner Summary: This study analyses whether unconscious priming attitudes towards older age might modify work performance. Participants were primed with the scrambled sentence task and then conducted a cognitive mail-sorting task. The findings indicate that the performance of older workers may indeed be modifiable by unconscious negative as well as positive priming.

Speech fluency profile on different tasks for individuals with Parkinson's disease.

PubMed

Juste, Fabiola Staróbole; Andrade, Claudia Regina Furquim de

2017-07-20

To characterize the speech fluency profile of patients with Parkinson's disease. Study participants were 40 individuals of both genders aged 40 to 80 years divided into 2 groups: Research Group - RG (20 individuals with diagnosis of Parkinson's disease) and Control Group - CG (20 individuals with no communication or neurological disorders). For all of the participants, three speech samples involving different tasks were collected: monologue, individual reading, and automatic speech. The RG presented a significant larger number of speech disruptions, both stuttering-like and typical dysfluencies, and higher percentage of speech discontinuity in the monologue and individual reading tasks compared with the CG. Both groups presented reduced number of speech disruptions (stuttering-like and typical dysfluencies) in the automatic speech task; the groups presented similar performance in this task. Regarding speech rate, individuals in the RG presented lower number of words and syllables per minute compared with those in the CG in all speech tasks. Participants of the RG presented altered parameters of speech fluency compared with those of the CG; however, this change in fluency cannot be considered a stuttering disorder.

How Do Children Deal With Conflict? A Developmental Study of Sequential Conflict Modulation

PubMed Central

Smulders, Silvan F. A.; Soetens, Eric L. L.; van der Molen, Maurits W.

2018-01-01

This study examined age-related differences in sequential conflict modulation (SCM), elicited in three tasks requiring the inhibition of pre-potent responses; a Simon task, an S-R compatibility (SRC) task and a hybrid Choice-reaction/NoGo task. The primary focus was on age-related changes in performance changes following a conflict trial. A secondary aim was to assess whether SCM follows different developmental trajectories depending on the type of conflict elicited by the tasks. The tasks were presented to three different groups of participants with an age range between 7- to 25-years—one group of participants for each task. For each task, the response-to-stimulus interval (RSI) was manipulated (50 vs. 500 ms) across trial blocks to assess time-dependent changes in conflict modulation. The results showed SCM for all three tasks, although the specific patterns differed between tasks and RSIs. Importantly, the magnitude of SCM decreased with advancing age, but this developmental trend did not survive when considering age-group differences in basic response speed. The current results contribute to the emerging evidence suggesting that patterns of SCM are task specific and were interpreted in terms of multiple bottom-up control mechanisms. PMID:29875718

Using Task Clarification, Graphic Feedback, And Verbal Feedback To Increase Closing-Task Completion In A Privately Owned Restaurant

PubMed Central

Weatherly, Nic L; Gravina, Nicole E

2005-01-01

An informant functional assessment was used to evaluate closing-task completion by servers and dishwashers at a restaurant. Based on the functional assessment results, an intervention consisting of task clarification, posted graphic feedback, and verbal feedback was implemented and evaluated with a multiple baseline design across two groups of employees. Results showed an increase of 15% and 38% in task completion for the two groups. PMID:15898481

Functional roles of the cingulo-frontal network in performance on working memory.

PubMed

Kondo, Hirohito; Morishita, Masanao; Osaka, Naoyuki; Osaka, Mariko; Fukuyama, Hidenao; Shibasaki, Hiroshi

2004-01-01

We examined the relationship between brain activities and task performance on working memory. A large-scale study was initially administered to identify good and poor performers using the operation span and reading span tasks. On the basis of those span scores, we divided 20 consenting participants into high- and low-span groups. In an fMRI study, the participants performed verification of arithmetic problems and retention of target words either concurrently or separately. The behavioral results showed that performance was better in the high-span group than in the low-span group under a dual-task condition, but not under two single-task conditions. The anterior cingulate cortex (ACC), left prefrontal cortex (PFC), left inferior frontal cortex, and bilateral parietal cortex were primarily activated for both span groups. We found that signal changes in the ACC were greater in the high-span group than in the low-span group under the dual-task condition, but not under the single-task conditions. Structural equation modeling indicated that an estimate of effective connectivity from the ACC to the left PFC was positive for the high-span group and negative for the-low span group, suggesting that closer cooperation between the two brain regions was strongly related to working memory performance. We conclude that central executive functioning for attention shifting is modulated by the cingulo-frontal network.

Physiological and psychological effects of delivering medical news using a simulated physician-patient scenario.

PubMed

Cohen, Lorenzo; Baile, Walter F; Henninger, Evelyn; Agarwal, Sandeep K; Kudelka, Andrzej P; Lenzi, Renato; Sterner, Janet; Marshall, Gailen D

2003-10-01

We examined the acute stress response associated with having to deliver either bad or good medical news using a simulated physician-patient scenario. Twenty-five healthy medical students were randomly assigned to a bad medical news (BN), a good medical news (GN), or a control group that read magazines during the session. Self-report measures were obtained before and after the task. Blood pressure and heart rate were measured throughout the task period. Four blood samples were obtained across the task period. The BN and GN tasks produced significant increases in self-reported distress and cardiovascular responses compared with the control group. There was also a significant increase in natural killer cell function 10 min into the task in the BN group compared with the control group. The BN task was also somewhat more stressful than the GN task, as shown by the self-report and cardiovascular data. These findings suggest that a simulated physician-patient scenario produces an acute stress response in the "physician," with the delivery of bad medical news more stressful than the delivery of good medical news.

Poor phonemic discrimination does not underlie poor verbal short-term memory in Down syndrome.

PubMed

Purser, Harry R M; Jarrold, Christopher

2013-05-01

Individuals with Down syndrome tend to have a marked impairment of verbal short-term memory. The chief aim of this study was to investigate whether phonemic discrimination contributes to this deficit. The secondary aim was to investigate whether phonological representations are degraded in verbal short-term memory in people with Down syndrome relative to control participants. To answer these questions, two tasks were used: a discrimination task, in which memory load was as low as possible, and a short-term recognition task that used the same stimulus items. Individuals with Down syndrome were found to perform significantly better than a nonverbal-matched typically developing group on the discrimination task, but they performed significantly more poorly than that group on the recognition task. The Down syndrome group was outperformed by an additional vocabulary-matched control group on the discrimination task but was outperformed to a markedly greater extent on the recognition task. Taken together, the results strongly indicate that phonemic discrimination ability is not central to the verbal short-term memory deficit associated with Down syndrome. Copyright © 2013 Elsevier Inc. All rights reserved.

Age Differences in the Transfer and Maintenance of Practice-Induced Improvements in Task Switching: The Impact of Working-Memory and Inhibition Demands

PubMed Central

Kray, Jutta; Fehér, Balázs

2017-01-01

Recent aging studies on training in task switching found that older adults showed larger improvements to an untrained switching task as younger adults do. However, less clear is what type of cognitive control processes can explain these training gains as participants were trained with a particular type of switching task including bivalent stimuli, requiring high inhibition demands, and no task cues helping them keeping track of the task sequence, and by this, requiring high working-memory (WM) demands. The aims of this study were first to specify whether inhibition, WM, or switching demands are critical for the occurrence of transfer and whether this transfer depends on the degree of overlap between training and transfer situation; and second to assess whether practiced-induced gains in task switching can be maintained over a longer period of time. To this end, we created five training conditions that varied in switching (switching vs. single task training), inhibition (switching training with bivalent or univalent stimuli), and WM demands (switching training with or without task cues). We investigated 81 younger adults and 82 older adults with a pretest-training-posttest design and a follow-up measurement after 6 months. Results indicated that all training and age groups showed improvements in task switching and a differential effect of training condition on improvements to an untrained switching task in younger and older adults. For younger adults, we found larger improvements in task switching for the switching groups than the single-task training group independently of inhibition and WM demands, suggesting that practice in switching is most critical. However, these benefits disappeared after 6 months. In contrast, for older adults training groups practicing task switching under high inhibition demands showed larger improvements to untrained switching tasks than the other groups. Moreover, these benefits were maintained over time. We also found that the transfer of benefits in task switching was larger with greater overlap between training and transfer situation. However, results revealed no evidence for transfer to other untrained cognitive task. Overall, the findings suggest that training in resolving interference while switching between two tasks is most critical for the occurrence of transfer in the elderly. PMID:28367135

Saccadic performance in questionnaire-identified schizotypes over time.

PubMed

Gooding, Diane C; Shea, Heather B; Matts, Christie W

2005-02-28

In the present study, 121 young adults (mean age=19 years), hypothesized to be at varying levels of risk for psychosis on the basis of their psychometric profiles, were administered saccadic (antisaccade and refixation) tasks at two separate assessments. At Time 1, individuals posited to be at heightened risk for the later development of schizophrenia-spectrum disorders (i.e., those individuals with elevated Social Anhedonia Scale [SAS] scores) produced significantly more antisaccade task errors than the controls. Despite apparent improvement in antisaccade task performance from initial testing to the follow-up (mean test-retest interval=59 months) across all groups, the Social Anhedonia (SocAnh) group continued to produce significantly more errors than the control group. The antisaccade task performance of the control group showed good temporal stability (Pearson's r=0.70, ICC=0.52), and the SocAnh group's performance showed excellent temporal stability (Pearson's r=0.85, ICC=0.83). The results of this investigation are twofold: First, antisaccade task performance is temporally stable, even in psychometrically identified schizotypes over long test-retest intervals; and secondly, Social Anhedonia Scale scores as well as Time 1 antisaccade task accuracy accounted for much of the variability in Time 2 antisaccade task performance. These findings add to the growing body of literature suggesting that antisaccade task deficits may serve as an endophenotypic marker of a schizophrenia diathesis.

Robotic technology results in faster and more robust surgical skill acquisition than traditional laparoscopy.

PubMed

Moore, Lee J; Wilson, Mark R; Waine, Elizabeth; Masters, Rich S W; McGrath, John S; Vine, Samuel J

2015-03-01

Technical surgical skills are said to be acquired quicker on a robotic rather than laparoscopic platform. However, research examining this proposition is scarce. Thus, this study aimed to compare the performance and learning curves of novices acquiring skills using a robotic or laparoscopic system, and to examine if any learning advantages were maintained over time and transferred to more difficult and stressful tasks. Forty novice participants were randomly assigned to either a robotic- or laparoscopic-trained group. Following one baseline trial on a ball pick-and-drop task, participants performed 50 learning trials. Participants then completed an immediate retention trial and a transfer trial on a two-instrument rope-threading task. One month later, participants performed a delayed retention trial and a stressful multi-tasking trial. The results revealed that the robotic-trained group completed the ball pick-and-drop task more quickly and accurately than the laparoscopic-trained group across baseline, immediate retention, and delayed retention trials. Furthermore, the robotic-trained group displayed a shorter learning curve for accuracy. The robotic-trained group also performed the more complex rope-threading and stressful multi-tasking transfer trials better. Finally, in the multi-tasking trial, the robotic-trained group made fewer tone counting errors. The results highlight the benefits of using robotic technology for the acquisition of technical surgical skills.

Grouping individual independent BOLD effects: a new way to ICA group analysis

NASA Astrophysics Data System (ADS)

Duann, Jeng-Ren; Jung, Tzyy-Ping; Sejnowski, Terrence J.; Makeig, Scott

2009-04-01

A new group analysis method to summarize the task-related BOLD responses based on independent component analysis (ICA) was presented. As opposite to the previously proposed group ICA (gICA) method, which first combined multi-subject fMRI data in either temporal or spatial domain and applied ICA decomposition only once to the combined fMRI data to extract the task-related BOLD effects, the method presented here applied ICA decomposition to the individual subjects' fMRI data to first find the independent BOLD effects specifically for each individual subject. Then, the task-related independent BOLD component was selected among the resulting independent components from the single-subject ICA decomposition and hence grouped across subjects to derive the group inference. In this new ICA group analysis (ICAga) method, one does not need to assume that the task-related BOLD time courses are identical across brain areas and subjects as used in the grand ICA decomposition on the spatially concatenated fMRI data. Neither does one need to assume that after spatial normalization, the voxels at the same coordinates represent exactly the same functional or structural brain anatomies across different subjects. These two assumptions have been problematic given the recent BOLD activation evidences. Further, since the independent BOLD effects were obtained from each individual subject, the ICAga method can better account for the individual differences in the task-related BOLD effects. Unlike the gICA approach whereby the task-related BOLD effects could only be accounted for by a single unified BOLD model across multiple subjects. As a result, the newly proposed method, ICAga, was able to better fit the task-related BOLD effects at individual level and thus allow grouping more appropriate multisubject BOLD effects in the group analysis.

Imitating actions on objects in early-onset and regressive autism: Effects and implications of task characteristics on performance

PubMed Central

Rogers, Sally J.; Young, Gregory S.; Cook, Ian; Giolzetti, Angelo; Ozonoff, Sally

2010-01-01

This study was designed to examine the nature of object imitation performance in early autism. We hypothesized that imitation would be relatively preserved when behaviors on objects resulted in salient instrumental effects. We designed tasks in which, in one condition, the motor action resulted in a salient, meaningful effect on an object, whereas in the other condition, the same action resulted in a less salient effect because of differing object characteristics. The motor aspects of the tasks did not vary across conditions. Four participant groups of 2- to 5-year-olds were examined: 17 children with early-onset autism, 24 children with regressive onset autism, 22 children with developmental delays, and 22 children with typical development. Groups were matched on nonverbal skills, and differences in verbal development were examined as a moderator of imitative ability. Results revealed an interaction of group by condition, with the combined autism group failing more tasks than the combined comparison groups, and failing more tasks in the less salient condition than in the more salient condition, as hypothesized. Analyses of autism subgroups revealed these effects were primarily because of the regression onset group. Accuracy of motor performance was examined by analyzing errors. Among children passing imitative acts, there were no group differences and no condition effects in the number, type, or pattern of performance errors. Among children passing the tasks, the group with autism did not demonstrate more emulation errors (imitating the goal but not the means) than other groups. There was no evidence that either motor or attentional aspects of the tasks contributed to the poorer imitative performance of the children with autism. PMID:20102648

All varieties of encoding variability are not created equal: Separating variable processing from variable tasks

PubMed Central

Huff, Mark J.; Bodner, Glen E.

2014-01-01

Whether encoding variability facilitates memory is shown to depend on whether item-specific and relational processing are both performed across study blocks, and whether study items are weakly versus strongly related. Variable-processing groups studied a word list once using an item-specific task and once using a relational task. Variable-task groups’ two different study tasks recruited the same type of processing each block. Repeated-task groups performed the same study task each block. Recall and recognition were greatest in the variable-processing group, but only with weakly related lists. A variable-processing benefit was also found when task-based processing and list-type processing were complementary (e.g., item-specific processing of a related list) rather than redundant (e.g., relational processing of a related list). That performing both item-specific and relational processing across trials, or within a trial, yields encoding-variability benefits may help reconcile decades of contradictory findings in this area. PMID:25018583

Transcranial Direct Current Stimulation to Enhance Dual-Task Gait Training in Parkinson's Disease: A Pilot RCT.

PubMed

Schabrun, Siobhan M; Lamont, Robyn M; Brauer, Sandra G

2016-01-01

To investigate the feasibility and safety of a combined anodal transcranial direct current stimulation (tDCS) and dual task gait training intervention in people with Parkinson's Disease (PD) and to provide data to support a sample size calculation for a fully powered trial should trends of effectiveness be present. A pilot, randomized, double-blind, sham-controlled parallel group trial with 12 week follow-up. A university physiotherapy department. Sixteen participants diagnosed with PD received nine dual task gait training sessions over 3 weeks. Participants were randomized to receive either active or sham tDCS applied for the first 20 minutes of each session. The primary outcome was gait speed while undertaking concurrent cognitive tasks (word lists, counting, conversation). Secondary measures included step length, cadence, Timed Up and Go, bradykinesia and motor speed. Gait speed, step length and cadence improved in both groups, under all dual task conditions. This effect was maintained at follow-up. There was no difference between the active and sham tDCS groups. Time taken to perform the TUGwords also improved, with no difference between groups. The active tDCS group did however increase their correct cognitive response rate during the TUGwords and TUGcount. Bradykinesia improved after training in both groups. Three weeks of dual task gait training resulted in improved gait under dual task conditions, and bradykinesia, immediately following training and at 12 weeks follow-up. The only parameter enhanced by tDCS was the number of correct responses while performing the dual task TUG. tDCS applied to M1 may not be an effective adjunct to dual task gait training in PD. Australia-New Zealand Clinical Trials Registry ACTRN12613001093774.

Event-related potential correlates of mindfulness meditation competence

PubMed Central

Atchley, Rachel; Klee, Dan; Memmott, Tabatha; Goodrich, Elena; Wahbeh, Helané; Oken, Barry

2016-01-01

Objective This cross-sectional study evaluated event-related potentials (ERPs) across three groups: naïve, novice, and experienced meditators as potential physiological markers of mindfulness meditation competence. Methods Electroencephalographic (EEG) data was collected during a target tone detection task and a Breath Counting task. The Breath Counting task served as the mindfulness meditation condition for the novice and experienced meditator groups. Participants were instructed to respond to target tones with a button press in the first task (Tones), and then ignore the primed tones while breath counting. The primary outcomes were ERP responses to target tones, namely the N2 and P3, as markers of stimulus discrimination and attention, respectively. Results As expected, P3 amplitudes elicited by target tones were attenuated within groups during the Breath Counting task in comparison to the Tones task (p < .001). There was a task by group interaction for P3 (p = .039). Both meditator groups displayed greater change in peak-to-trough P3 amplitudes, with higher amplitudes during the Tones condition and more pronounced reductions in P3 amplitudes during the Breath Counting meditation task in comparison to the naïve group. Conclusions Meditators had stronger P3 amplitude responses to target tones when instructed to attend to the tones, and a greater attenuation of P3 amplitudes when instructed to ignore the same tones during the Breath Counting task. This study introduces the idea of identifying ERP markers as a means of measuring mindfulness meditation competence, and results suggest this may be a valid approach. This information has the potential to improve mindfulness meditation interventions by allowing objective assessment of mindfulness meditation quality. PMID:26850995

Event-related potential correlates of mindfulness meditation competence.

PubMed

Atchley, R; Klee, D; Memmott, T; Goodrich, E; Wahbeh, H; Oken, B

2016-04-21

This cross-sectional study evaluated event-related potentials (ERPs) across three groups: naïve, novice, and experienced meditators as potential physiological markers of mindfulness meditation competence. Electroencephalographic (EEG) data were collected during a target tone detection task and a Breath Counting task. The Breath Counting task served as the mindfulness meditation condition for the novice and experienced meditator groups. Participants were instructed to respond to target tones with a button press in the first task (Tones), and then ignore the primed tones while Breath Counting. The primary outcomes were ERP responses to target tones, namely the N2 and P3, as markers of stimulus discrimination and attention, respectively. As expected, P3 amplitudes elicited by target tones were attenuated within groups during the Breath Counting task in comparison to the Tones task (p<.001). There was a task by group interaction for P3 (p=.039). Both meditator groups displayed greater change in peak-to-trough P3 amplitudes, with higher amplitudes during the Tones condition and more pronounced reductions in P3 amplitudes during the Breath Counting meditation task in comparison to the naïve group. Meditators had stronger P3 amplitude responses to target tones when instructed to attend to the tones, and a greater attenuation of P3 amplitudes when instructed to ignore the same tones during the Breath Counting task. This study introduces the idea of identifying ERP markers as a means of measuring mindfulness meditation competence, and results suggest this may be a valid approach. This information has the potential to improve mindfulness meditation interventions by allowing objective assessment of mindfulness meditation quality. Published by Elsevier Ltd.

Design and Validation of an Open-Source, Partial Task Trainer for Endonasal Neuro-Endoscopic Skills Development: Indian Experience.

PubMed

Singh, Ramandeep; Baby, Britty; Damodaran, Natesan; Srivastav, Vinkle; Suri, Ashish; Banerjee, Subhashis; Kumar, Subodh; Kalra, Prem; Prasad, Sanjiva; Paul, Kolin; Anand, Sneh; Kumar, Sanjeev; Dhiman, Varun; Ben-Israel, David; Kapoor, Kulwant Singh

2016-02-01

Box trainers are ideal simulators, given they are inexpensive, accessible, and use appropriate fidelity. The development and validation of an open-source, partial task simulator that teaches the fundamental skills necessary for endonasal skull-base neuro-endoscopic surgery. We defined the Neuro-Endo-Trainer (NET) SkullBase-Task-GraspPickPlace with an activity area by analyzing the computed tomography scans of 15 adult patients with sellar suprasellar parasellar tumors. Four groups of participants (Group E, n = 4: expert neuroendoscopists; Group N, n =19: novice neurosurgeons; Group R, n = 11: neurosurgery residents with multiple iterations; and Group T, n = 27: neurosurgery residents with single iteration) performed grasp, pick, and place tasks using NET and were graded on task completion time and skills assessment scale score. Group E had lower task completion times and greater skills assessment scale scores than both Group N and R (P ≤ 0.03, 0.001). The performance of Groups N and R was found to be equivalent; in self-assessing neuro-endoscopic skill, the participants in these groups were found to have equally low pretraining scores (4/10) with significant improvement shown after NET simulation (6, 7 respectively). Angled scopes resulted in decreased scores with tilted plates compared with straight plates (30° P ≤ 0.04, 45° P ≤ 0.001). With tilted plates, decreased scores were observed when we compared the 0° with 45° endoscope (right, P ≤ 0.008; left, P ≤ 0.002). The NET, a face and construct valid open-source partial task neuroendoscopic trainer, was designed. Presimulation novice neurosurgeons and neurosurgical residents were described as having insufficient skills and preparation to practice neuro-endoscopy. Plate tilt and endoscope angle were shown to be important factors in participant performance. The NET was found to be a useful partial-task trainer for skill building in neuro-endoscopy. Copyright © 2016 Elsevier Inc. All rights reserved.

Semantic Verbal Fluency in Children with and without Autism Spectrum Disorder: Relationship with Chronological Age and IQ

PubMed Central

Pastor-Cerezuela, Gemma; Fernández-Andrés, Maria-Inmaculada; Feo-Álvarez, Mireia; González-Sala, Francisco

2016-01-01

We administered a semantic verbal fluency (SVF) task to two groups of children (age range from 5 to 8): 47 diagnosed with Autism Spectrum Disorder (ASD Group) and 53 with typical development (Comparison Group), matched on gender, chronological age, and non-verbal IQ. Four specific indexes were calculated from the SVF task, reflecting the different underlying cognitive strategies used: clustering (component of generativity and lexical-semantic access), and switching (executive component, cognitive flexibility). First, we compared the performance of the two groups on the different SVF task indicators, with the ASD group scoring lower than the Comparison Group, although the difference was greater on switching than on clustering. Second, we analyzed the relationships between the different SVF measures and chronological age, verbal IQ and non-verbal IQ. While in the Comparison Group chronological age was the main predictor of performance on the SVF task, in the ASD Group verbal IQ was the best predictor. In the children with ASD, therefore, greater linguistic competence would be associated with better performance on the SVF task, which should be taken into account in speech therapies designed to achieve improvements in linguistic generativity and cognitive flexibility. PMID:27379002

Functional magnetic resonance imaging of divergent and convergent thinking in Big-C creativity.

PubMed

Japardi, Kevin; Bookheimer, Susan; Knudsen, Kendra; Ghahremani, Dara G; Bilder, Robert M

2018-02-15

The cognitive and physiological processes underlying creativity remain unclear, and very few studies to date have attempted to identify the behavioral and brain characteristics that distinguish exceptional ("Big-C") from everyday ("little-c") creativity. The Big-C Project examined functional brain responses during tasks demanding divergent and convergent thinking in 35 Big-C Visual Artists (VIS), 41 Big-C Scientists (SCI), and 31 individuals in a "smart comparison group" (SCG) matched to the Big-C groups on parental educational attainment and estimated IQ. Functional MRI (fMRI) scans included two activation paradigms widely used in prior creativity research, the Alternate Uses Task (AUT) and Remote Associates Task (RAT), to assess brain function during divergent and convergent thinking, respectively. Task performance did not differ between groups. Functional MRI activation in Big-C and SCG groups differed during the divergent thinking task. No differences in activation were seen during the convergent thinking task. Big-C groups had less activation than SCG in frontal pole, right frontal operculum, left middle frontal gyrus, and bilaterally in occipital cortex. SCI displayed lower frontal and parietal activation relative to the SCG when generating alternate uses in the AUT, while VIS displayed lower frontal activation than SCI and SCG when generating typical qualities (the control condition in the AUT). VIS showed more activation in right inferior frontal gyrus and left supramarginal gyrus relative to SCI. All groups displayed considerable overlapping activation during the RAT. The results confirm substantial overlap in functional activation across groups, but suggest that exceptionally creative individuals may depend less on task-positive networks during tasks that demand divergent thinking. Published by Elsevier Ltd.

Perceptual grouping enhances visual plasticity.

PubMed

Mastropasqua, Tommaso; Turatto, Massimo

2013-01-01

Visual perceptual learning, a manifestation of neural plasticity, refers to improvements in performance on a visual task achieved by training. Attention is known to play an important role in perceptual learning, given that the observer's discriminative ability improves only for those stimulus feature that are attended. However, the distribution of attention can be severely constrained by perceptual grouping, a process whereby the visual system organizes the initial retinal input into candidate objects. Taken together, these two pieces of evidence suggest the interesting possibility that perceptual grouping might also affect perceptual learning, either directly or via attentional mechanisms. To address this issue, we conducted two experiments. During the training phase, participants attended to the contrast of the task-relevant stimulus (oriented grating), while two similar task-irrelevant stimuli were presented in the adjacent positions. One of the two flanking stimuli was perceptually grouped with the attended stimulus as a consequence of its similar orientation (Experiment 1) or because it was part of the same perceptual object (Experiment 2). A test phase followed the training phase at each location. Compared to the task-irrelevant no-grouping stimulus, orientation discrimination improved at the attended location. Critically, a perceptual learning effect equivalent to the one observed for the attended location also emerged for the task-irrelevant grouping stimulus, indicating that perceptual grouping induced a transfer of learning to the stimulus (or feature) being perceptually grouped with the task-relevant one. Our findings indicate that no voluntary effort to direct attention to the grouping stimulus or feature is necessary to enhance visual plasticity.

The Effects of Group Relaxation Training/Large Muscle Exercise, and Parental Involvement on Attention to Task, Impulsivity, and Locus of Control among Hyperactive Boys.

ERIC Educational Resources Information Center

Porter, Sally S.; Omizo, Michael M.

1984-01-01

The study examined the effects of group relaxation training/large muscle exercise and parental involvement on attention to task, impulsivity, and locus of control among 34 hyperactive boys. Following treatment both experimental groups recorded significantly higher attention to task, lower impulsivity, and lower locus of control scores. (Author/CL)

Adaptation and Retention of a Perceptual-Motor Task in Children: Effects of a Single Bout of Intense Endurance Exercise.

PubMed

Ferrer-Uris, Blai; Busquets, Albert; Angulo-Barroso, Rosa

2018-02-01

We assessed the effect of an acute intense exercise bout on the adaptation and consolidation of a visuomotor adaptation task in children. We also sought to assess if exercise and learning task presentation order could affect task consolidation. Thirty-three children were randomly assigned to one of three groups: (a) exercise before the learning task, (b) exercise after the learning task, and (c) only learning task. Baseline performance was assessed by practicing the learning task in a 0° rotation condition. Afterward, a 60° rotation-adaptation set was applied followed by three rotated retention sets after 1 hr, 24 hr, and 7 days. For the exercise groups, exercise was presented before or after the motor adaptation. Results showed no group differences during the motor adaptation while exercise seemed to enhance motor consolidation. Greater consolidation enhancement was found in participants who exercised before the learning task. Our data support the importance of exercise to improve motor-memory consolidation in children.

Attentional blink in children with attention deficit hyperactivity disorder.

PubMed

Amador-Campos, Juan A; Aznar-Casanova, J Antonio; Bezerra, Izabela; Torro-Alves, Nelson; Sánchez, Manuel M

2015-01-01

To explore the temporal mechanism of attention in children with attention deficit hyperactivity disorder (ADHD) and controls using a rapid serial visual presentation (RSVP) task in which two letters (T1 and T2) were presented in close temporal proximity among distractors (attentional blink [AB]). Thirty children aged between 9 and 13 years (12 with ADHD combined type and 18 controls) took part in the study. Both groups performed two kinds of RSVP task. In the single task, participants simply had to identify a target letter (T1), whereas in the dual task, they had to identify a target letter (T1) and a probe letter (T2). The ADHD and control groups were equivalent in their single-task performance. However, in the dual-task condition, there were significant between-group differences in the rate of detection of the probe letter (T2) at lag + 1 and lag + 4. The ADHD group exhibited a larger overall AB compared with controls. Our findings provide support for a link between ADHD and attentional blink.

Age-related differences in dual task performance: A cross-sectional study on women.

PubMed

Brustio, Paolo R; Magistro, Daniele; Rabaglietti, Emanuela; Liubicich, Monica E

2017-02-01

Simultaneous performances of motor and attention-demanding tasks are common in activities of everyday life. The present cross-sectional study examined the changes and age-related differences on mobility performance with an additional cognitive or motor task, and evaluated the relative dual-task cost (DTC) on the motor performance in young, middle-aged and older women. A total of 30 young (mean age 25.12 ± 3.00 years), 30 middle-aged (mean age 47.82 ± 5.06 years) and 30 older women (mean age 72.74 ± 5.95 years) were recruited. Participants carried out: (i) single task: Timed Up & Go Test; (ii) cognitive dual-task: Timed Up & Go Test while counting backwards by three; (iii) manual dual-task: Timed Up & Go Test while carrying a glass of water. A repeated measures anova with between-factor as age groups and within-factor as tasks was carried out to assess the effect of aging on the performance of mobility tasks. DTC was calculated as ([performance in single-task - performance in dual-task] / performance in single task) × 100%. One-way ancova were carried out to compare the DTC among the three age groups. A significant interaction between age groups and task (F 4,172  = 6.716, P < 0.001, partial η 2  = 0.135) was observed. Specifically, older women showed a worse mobility performance under dual-task condition compared with young and middle-aged groups. Furthermore, DTC differences in cognitive task were observed in older women compared with younger and middle-aged women (F 2,86  = 7.649, P < 0.001, partial η 2  = 0.151), but not in manual task. Dual-task conditions might affect mobility performance differently across the lifespan, and could be particularly challenging in older women. Geriatr Gerontol Int 2017; 17: 315-321. © 2015 Japan Geriatrics Society.

The effects of a concurrent task on walking in persons with transfemoral amputation compared to persons without limb loss.

PubMed

Morgan, Sara J; Hafner, Brian J; Kelly, Valerie E

2016-08-01

Many people with lower limb loss report the need to concentrate on walking. This may indicate increased reliance on cognitive resources when walking compared to individuals without limb loss. This study quantified changes in walking associated with addition of a concurrent cognitive task in persons with transfemoral amputation using microprocessor knees compared to age- and sex-matched controls. Observational, cross-sectional study. Quantitative motion analysis was used to assess walking under both single-task (walking alone) and dual-task (walking while performing a cognitive task) conditions. Primary outcomes were walking speed, step width, step time asymmetry, and cognitive task response latency and accuracy. Repeated-measures analysis of variance was used to examine the effects of task (single-task and dual-task) and group (transfemoral amputation and control) for each outcome. No significant interactions between task and group were observed (all p > 0.11) indicating that a cognitive task did not differentially affect walking between groups. However, walking was slower with wider steps and more asymmetry in people with transfemoral amputation compared to controls under both conditions. Although there were significant differences in walking between people with transfemoral amputation and matched controls, the effects of a concurrent cognitive task on walking were similar between groups. The addition of a concurrent task did not differentially affect walking outcomes in people with and without transfemoral amputation. However, compared to people without limb loss, people with transfemoral amputation adopted a conservative walking strategy. This strategy may reduce the need to concentrate on walking but also contributed to notable gait deviations. © The International Society for Prosthetics and Orthotics 2015.

Deductive and inductive reasoning in obsessive-compulsive disorder.

PubMed

Pélissier, Marie-Claude; O'Connor, Kieron P

2002-03-01

This study tested the hypothesis that people with obsessive-compulsive disorder (OCD) show an inductive reasoning style distinct from people with generalized anxiety disorder (GAD) and from participants in a non-anxious (NA) control group. The experimental procedure consisted of administering a range of six deductive and inductive tasks and a probabilistic task in order to compare reasoning processes between groups. Recruitment was in the Montreal area within a French-speaking population. The participants were 12 people with OCD, 12 NA controls and 10 people with GAD. Participants completed a series of written and oral reasoning tasks including the Wason Selection Task, a Bayesian probability task and other inductive tasks, designed by the authors. There were no differences between groups in deductive reasoning. On an inductive "bridging task", the participants with OCD always took longer than the NA control and GAD groups to infer a link between two statements and to elaborate on this possible link. The OCD group alone showed a significant decrease in their degree of conviction about an arbitrary statement after inductively generating reasons to support this statement. Differences in probabilistic reasoning replicated those of previous authors. The results pinpoint the importance of examining inference processes in people with OCD in order to further refine the clinical applications of behavioural-cognitive therapy for this disorder.

Musical dual-task training in patients with mild-to-moderate dementia: a randomized controlled trial.

PubMed

Chen, Yu-Ling; Pei, Yu-Cheng

2018-01-01

Dual-task training may improve dual-task gait performance, balance, and cognition in older adults with and without cognitive impairment. Although music has been widely utilized in dementia management, there are no existing protocols for music-based dual-task training. This randomized controlled study developed a Musical Dual-Task Training (MDTT) protocol that patients with dementia can use to practice walking and making music simultaneously, to enhance attention control in patients during dual-tasking. Twenty-eight adults diagnosed with mild-to-moderate dementia were assigned to the MDTT (n=15) or control groups (n=13). The MDTT group received MDTT, while the control group participated in non-musical cognitive and walking activities. The effects of MDTT were evaluated through the primary outcome of attention control, and secondary outcomes of dual-task performance, balance, falls efficacy, and agitation. The MDTT group showed a significant improvement in attention control, while the control group did not ( P <0.001). A significant effect favored MDTT over control treatment for the secondary outcome of falls efficacy ( P =0.02) and agitation ( P <0.01). MDTT, a music therapy intervention that demands a high level of cognitive processing, enhances attention control, falls efficacy, and helps alleviate agitation in patients with mild-to-moderate dementia.

Musical dual-task training in patients with mild-to-moderate dementia: a randomized controlled trial

PubMed Central

Chen, Yu-Ling; Pei, Yu-Cheng

2018-01-01

Background/aims Dual-task training may improve dual-task gait performance, balance, and cognition in older adults with and without cognitive impairment. Although music has been widely utilized in dementia management, there are no existing protocols for music-based dual-task training. This randomized controlled study developed a Musical Dual-Task Training (MDTT) protocol that patients with dementia can use to practice walking and making music simultaneously, to enhance attention control in patients during dual-tasking. Methods Twenty-eight adults diagnosed with mild-to-moderate dementia were assigned to the MDTT (n=15) or control groups (n=13). The MDTT group received MDTT, while the control group participated in non-musical cognitive and walking activities. The effects of MDTT were evaluated through the primary outcome of attention control, and secondary outcomes of dual-task performance, balance, falls efficacy, and agitation. Results The MDTT group showed a significant improvement in attention control, while the control group did not (P<0.001). A significant effect favored MDTT over control treatment for the secondary outcome of falls efficacy (P=0.02) and agitation (P<0.01). Conclusion MDTT, a music therapy intervention that demands a high level of cognitive processing, enhances attention control, falls efficacy, and helps alleviate agitation in patients with mild-to-moderate dementia. PMID:29881275

Group social rank is associated with performance on a spatial learning task.

PubMed

Langley, Ellis J G; van Horik, Jayden O; Whiteside, Mark A; Madden, Joah R

2018-02-01

Dominant individuals differ from subordinates in their performances on cognitive tasks across a suite of taxa. Previous studies often only consider dyadic relationships, rather than the more ecologically relevant social hierarchies or networks, hence failing to account for how dyadic relationships may be adjusted within larger social groups. We used a novel statistical method: randomized Elo-ratings, to infer the social hierarchy of 18 male pheasants, Phasianus colchicus , while in a captive, mixed-sex group with a linear hierarchy. We assayed individual learning performance of these males on a binary spatial discrimination task to investigate whether inter-individual variation in performance is associated with group social rank. Task performance improved with increasing trial number and was positively related to social rank, with higher ranking males showing greater levels of success. Motivation to participate in the task was not related to social rank or task performance, thus indicating that these rank-related differences are not a consequence of differences in motivation to complete the task. Our results provide important information about how variation in cognitive performance relates to an individual's social rank within a group. Whether the social environment causes differences in learning performance or instead, inherent differences in learning ability predetermine rank remains to be tested.

Planning and Performance in Small Groups: Collective Implementation Intentions Enhance Group Goal Striving.

PubMed

Thürmer, J Lukas; Wieber, Frank; Gollwitzer, Peter M

2017-01-01

There are two key motivators to perform well in a group: making a contribution that (a) is crucial for the group (indispensability) and that (b) the other group members recognize (identifiability). We argue that indispensability promotes setting collective ("We") goals whereas identifiability induces individual ("I") goals. Although both goals may enhance performance, they should align with different strategies. Whereas pursuing collective goals should involve more cooperation, pursuing individual goals should involve less cooperation. Two experiments support this reasoning and show that planning out collective goals with collective implementation intentions (cIIs or "We-plans") relies on cooperation but planning out individual goals with individual implementation intentions (IIs or "I-plans") does not. In Experiment 1, three-member groups first formed a collective or an individual goal and then performed a first round of a physical persistence task. Groups then either formed a respective implementation intention (cII or II) or a control plan and then performed a second round of the task. Although groups with cIIs and IIs performed better on a physical persistence task than respective control groups, only cII groups interacted more cooperatively during task performance. To confirm the causal role of these interaction processes, Experiment 2 used the same persistence task and manipulated whether groups could communicate: When communication was hindered, groups with cIIs but not groups with IIs performed worse. Communication thus qualifies as a process making cIIs effective. The present research offers a psychology of action account to small group performance.

Concurrent Path Planning with One or More Humanoid Robots

NASA Technical Reports Server (NTRS)

Reiland, Matthew J. (Inventor); Sanders, Adam M. (Inventor)

2014-01-01

A robotic system includes a controller and one or more robots each having a plurality of robotic joints. Each of the robotic joints is independently controllable to thereby execute a cooperative work task having at least one task execution fork, leading to multiple independent subtasks. The controller coordinates motion of the robot(s) during execution of the cooperative work task. The controller groups the robotic joints into task-specific robotic subsystems, and synchronizes motion of different subsystems during execution of the various subtasks of the cooperative work task. A method for executing the cooperative work task using the robotic system includes automatically grouping the robotic joints into task-specific subsystems, and assigning subtasks of the cooperative work task to the subsystems upon reaching a task execution fork. The method further includes coordinating execution of the subtasks after reaching the task execution fork.

Breath Group Analysis for Reading and Spontaneous Speech in Healthy Adults

PubMed Central

Wang, Yu-Tsai; Green, Jordan R.; Nip, Ignatius S.B.; Kent, Ray D.; Kent, Jane Finley

2010-01-01

Aims The breath group can serve as a functional unit to define temporal and fundamental frequency (f0) features in continuous speech. These features of the breath group are determined by the physiologic, linguistic, and cognitive demands of communication. Reading and spontaneous speech are two speaking tasks that vary in these demands and are commonly used to evaluate speech performance for research and clinical applications. The purpose of this study is to examine differences between reading and spontaneous speech in the temporal and f0 aspects of their breath groups. Methods Sixteen participants read two passages and answered six questions while wearing a circumferentially vented mask connected to a pneumotach. The aerodynamic signal was used to identify inspiratory locations. The audio signal was used to analyze task differences in breath group structure, including temporal and f0 components. Results The main findings were that spontaneous speech task exhibited significantly more grammatically inappropriate breath group locations and longer breath group duration than did the passage reading task. Conclusion The task differences in the percentage of grammatically inadequate breath group locations and in breath group duration for healthy adult speakers partly explain the differences in cognitive-linguistic load between the passage reading and spontaneous speech. PMID:20588052

Breath group analysis for reading and spontaneous speech in healthy adults.

PubMed

Wang, Yu-Tsai; Green, Jordan R; Nip, Ignatius S B; Kent, Ray D; Kent, Jane Finley

2010-01-01

The breath group can serve as a functional unit to define temporal and fundamental frequency (f0) features in continuous speech. These features of the breath group are determined by the physiologic, linguistic, and cognitive demands of communication. Reading and spontaneous speech are two speaking tasks that vary in these demands and are commonly used to evaluate speech performance for research and clinical applications. The purpose of this study is to examine differences between reading and spontaneous speech in the temporal and f0 aspects of their breath groups. Sixteen participants read two passages and answered six questions while wearing a circumferentially vented mask connected to a pneumotach. The aerodynamic signal was used to identify inspiratory locations. The audio signal was used to analyze task differences in breath group structure, including temporal and f0 components. The main findings were that spontaneous speech task exhibited significantly more grammatically inappropriate breath group locations and longer breath group duration than did the passage reading task. The task differences in the percentage of grammatically inadequate breath group locations and in breath group duration for healthy adult speakers partly explain the differences in cognitive-linguistic load between the passage reading and spontaneous speech. Copyright © 2010 S. Karger AG, Basel.

Inhibition Plasticity in Older Adults: Practice and Transfer Effects Using a Multiple Task Approach.

PubMed

Wilkinson, Andrea J; Yang, Lixia

2016-01-01

OBJECTIVE. To examine plasticity of inhibition, as indexed by practice effects of inhibition tasks and the associated transfer effects, using a multiple task approach in healthy older adults. METHOD. Forty-eight healthy older adults were evenly assigned to either a practice group or a no-contact control group. All participants completed pretest (2.5 hours) and posttest (2 hours) sessions, with a 2-week interval in between. During the 2-week interval, only the practice group completed six 30-minute practice sessions (three sessions per week for two consecutive weeks) of three lab-based inhibition tasks. RESULTS. All three inhibition tasks demonstrated significant improvement across practice sessions, suggesting practice-induced plasticity. The benefit, however, only transferred to near-near tasks. The results are inconclusive with regard to the near-far and far-far transfer effects. DISCUSSION. This study further extends literature on practice effects of inhibition in older adults by using a multiple task approach. Together with previous work, the current study suggests that older adults are able to improve inhibition performance through practice and transfer the practice gains to tasks that overlap in both target cognitive ability and task structure (i.e., near-near tasks).

Inhibition Plasticity in Older Adults: Practice and Transfer Effects Using a Multiple Task Approach

PubMed Central

Wilkinson, Andrea J.; Yang, Lixia

2016-01-01

Objective. To examine plasticity of inhibition, as indexed by practice effects of inhibition tasks and the associated transfer effects, using a multiple task approach in healthy older adults. Method. Forty-eight healthy older adults were evenly assigned to either a practice group or a no-contact control group. All participants completed pretest (2.5 hours) and posttest (2 hours) sessions, with a 2-week interval in between. During the 2-week interval, only the practice group completed six 30-minute practice sessions (three sessions per week for two consecutive weeks) of three lab-based inhibition tasks. Results. All three inhibition tasks demonstrated significant improvement across practice sessions, suggesting practice-induced plasticity. The benefit, however, only transferred to near-near tasks. The results are inconclusive with regard to the near-far and far-far transfer effects. Discussion. This study further extends literature on practice effects of inhibition in older adults by using a multiple task approach. Together with previous work, the current study suggests that older adults are able to improve inhibition performance through practice and transfer the practice gains to tasks that overlap in both target cognitive ability and task structure (i.e., near-near tasks). PMID:26885407

People with stroke who fail an obstacle crossing task have a higher incidence of falls and utilize different gait patterns compared with people who pass the task.

PubMed

Said, Catherine M; Galea, Mary P; Lythgo, Noel

2013-03-01

Obstacle crossing is impaired in people following stroke. It is not known whether people with stroke who fail an obstacle crossing task have more falls or whether the gait adjustments used to cross an obstacle differ from those used by people who pass the task. The purposes of this study were (1) to identify whether a group of people with stroke who failed an obstacle crossing task had a greater incidence of falling and (2) to determine whether people who fail an obstacle crossing task utilize different gait adjustments. This was a prospective, observational study. Thirty-two participants with a recent stroke were recruited. Participants walked at self-selected speed and stepped over a 4-cm-high obstacle. Performance was rated as pass or fail, and spatiotemporal, center of mass (COM), and center of pressure (COP) data were collected. Prospective falls data were recorded for 20 participants over a 6-month period. The incidence of fallers was significantly higher (incidence rate=0.833) in the group that failed the obstacle crossing task than in the group that passed the task (incidence rate=0.143). The group that failed the task had a slower walking speed and greater normalized separation between the trail heel (unaffected support limb) and COM as the affected lead toe cleared the obstacle. This group exhibited greater normalized times from affected lead toe clearance to landing, unaffected trail toe clearance to landing, and affected trail toe-off to toe clearance. The sample size was small, and falls data were available for only 20 participants. Obstacle crossing is an important task to consider in people following stroke and may be useful in identifying those at risk of falls.

Task- and self-related pathways to deep learning: the mediating role of achievement goals, classroom attentiveness, and group participation.

PubMed

Lau, Shun; Liem, Arief Darmanegara; Nie, Youyan

2008-12-01

The expectancy-value and achievement goal theories are arguably the two most dominant theories of achievement motivation in the contemporary literature. However, very few studies have examined how the constructs derived from both theories are related to deep learning. Moreover, although there is evidence demonstrating the links between achievement goals and deep learning, little research has examined the mediating processes involved. The aims of this research were to: (a) investigate the role of task- and self-related beliefs (task value and self-efficacy) as well as achievement goals in predicting deep learning in mathematics and (b) examine how classroom attentiveness and group participation mediated the relations between achievement goals and deep learning. The sample comprised 1,476 Grade-9 students from 39 schools in Singapore. Students' self-efficacy, task value, achievement goals, classroom attentiveness, group participation, and deep learning in mathematics were assessed by a self-reported questionnaire administered on-line. Structural equation modelling was performed to test the hypothesized model linking these variables. Task value was predictive of task-related achievement goals whereas self-efficacy was predictive of task-approach, performance-approach, and performance-avoidance goals. Achievement goals were found to fully mediate the relations between task value and self-efficacy on the one hand, and classroom attentiveness, group participation, and deep learning on the other. Classroom attentiveness and group participation partially mediated the relations between achievement goal adoption and deep learning. The findings suggest that (a) task- and self-related pathways are two possible routes through which students could be motivated to learn and (b) like task-approach goals, performance-approach goals could lead to adaptive processes and outcomes.

The effect of cognitive-motor dual-task training on cognitive function and plasma amyloid β peptide 42/40 ratio in healthy elderly persons: a randomized controlled trial.

PubMed

Yokoyama, Hisayo; Okazaki, Kazunobu; Imai, Daiki; Yamashina, Yoshihiro; Takeda, Ryosuke; Naghavi, Nooshin; Ota, Akemi; Hirasawa, Yoshikazu; Miyagawa, Toshiaki

2015-05-28

Physical activity reduces the incidence and progression of cognitive impairment. Cognitive-motor dual-task training, which requires dividing attention between cognitive tasks and exercise, may improve various cognitive domains; therefore, we examined the effect of dual-task training on the executive functions and on plasma amyloid β peptide (Aβ) 42/40 ratio, a potent biomarker of Alzheimer's disease, in healthy elderly people. Twenty-seven sedentary elderly people participated in a 12-week randomized, controlled trial. The subjects assigned to the dual-task training (DT) group underwent a specific cognitive-motor dual-task training, and then the clinical outcomes, including cognitive functions by the Modified Mini-Mental State (3MS) examination and the Trail-Making Test (TMT), and the plasma Aβ 42/40 ratio following the intervention were compared with those of the control single-task training (ST) group by unpaired t-test. Among 27 participants, 25 completed the study. The total scores in the 3MS examination as well as the muscular strength of quadriceps were equally improved in both groups after the training. The specific cognitive domains, "registration & recall", "attention", "verbal fluency & understanding", and "visuospatial skills" were significantly improved only in the DT group. Higher scores in "attention", "verbal fluency & understanding", and "similarities" were found in the DT group than in the ST group at post-intervention. The absolute changes in the total (8.5 ± 1.6 vs 2.4 ± 0.9, p = 0.004, 95 % confidence interval (CI) 0.75-3.39) and in the scores of "attention" (1.9 ± 0.5 vs -0.2 ± 0.4, p = 0.004, 95 % CI 2.25-9.98) were greater in the DT group than in the ST group. We found no changes in the TMT results in either group. Plasma Aβ 42/40 ratio decreased in both groups following the training (ST group: 0.63 ± 0.13 to 0.16 ± 0.03, p = 0.001; DT group: 0.60 ± 0.12 to 0.25 ± 0.06, p = 0.044), although the pre- and post-intervention values were not different between the groups for either measure. Cognitive-motor dual-task training was more beneficial than single-task training alone in improving broader domains of cognitive functions of elderly persons, and the improvement was not directly due to modulating Aβ metabolism.

Exploring the disruptive effects of psychopathy and aggression on group processes and group effectiveness.

PubMed

Baysinger, Michael A; Scherer, Kelly T; LeBreton, James M

2014-01-01

The present research examines the influence of implicit and explicit personality characteristics on group process and effectiveness. Individuals from 112 groups participated in 2 problem-solving tasks and completed measures of group process and effectiveness. Results indicated that groups characterized by higher levels of psychopathy and implicit aggression tended to have more dysfunctional interactions and negative perceptions of the group. In addition, task participation and negative socioemotional behaviors fully mediated the relationship between group personality traits and group commitment and cohesion, and negative socioemotional behaviors fully mediated the relationship between group personality and performance on both tasks. Implications of antisocial traits for group interactions and performance, as well as for future theory and research, are discussed. PsycINFO Database Record (c) 2014 APA, all rights reserved

SA45. Amotivation in Schizophrenia, Bipolar Disorder, and Major Depressive Disorder: A Preliminary Comparison Study

PubMed Central

Zou, Ying-min; Ni, Ke; Wang, Yang-yu; Yu, En-qing; Lui, Simon S. Y.; Cheung, Eric F. C.; Chan, Raymond C. K.

2017-01-01

Abstract Background: Deficits in reward processing, such as approaching motivation, reward learning and effort-based decision-making, have been observed in patients with schizophrenia (SCZ), bipolar disorder (BD), and major depressive disorder (MDD). However, little is known about the nature of reward-processing deficits in these 3 diagnostic groups. The present study aimed to compare and contrast amotivation in these 3 diagnostic groups using an effort-based decision-making task. Methods: Sixty patients (19 SCZ patients, 18 BD patients and 23 MDD patients) and 27 healthy controls (HC) were recruited for the present study. The Effort Expenditure for Reward Task (EEfRT) was administered to evaluate their effort allocation pattern. This task required participants to choose easy or hard tasks in response to different levels of reward magnitude and reward probability. Results: Results showed that SCZ, BD, and MDD patients chose fewer hard tasks compared to HC. As reward magnitude increased, MDD patients made the least effort to gain reward compared to the other groups. When reward probability was intermediate, MDD patients chose fewer hard tasks than SCZ patients, whereas BD patients and HC chose more hard tasks than MDD and SCZ patients. When the reward probability was high, all 3 groups of patients tried fewer hard tasks than HC. Moreover, SCZ and MDD patients were less likely to choose hard tasks than BD patients and HC in the intermediate estimated value conditions. However, in the highest estimated value condition, there was no group difference in hard task choices between these 3 clinical groups, and they were all less motivated than HC. Conclusion: SCZ, BD, and MDD patients shared common deficits in gaining reward if the reward probability and estimated value were high. SCZ and MDD patients showed less motivation than BD patients in gaining reward when the reward probability and estimated value was intermediate.

Successful Transfer of a Motor Learning Strategy to a Novel Sport.

PubMed

Kearney, Philip E; Judge, Phil

2017-10-01

This study investigated whether secondary school students who were taught a motor learning strategy could transfer their knowledge of the strategy to learning a novel task. Twenty adolescents were randomly allocated to a strategy or control group. The strategy group was taught Singer's five-step learning strategy, while the control group received information on the evolution and biomechanics of the basketball free throw. Both groups received three 1-hour practice sessions on a modified basketball shooting task. After one month, participants were introduced to the transfer task, golf putting. Performance accuracy was recorded for all tasks, and participants completed questionnaires regarding strategy use during practice. Participants taught the five-step learning strategy successfully recalled and applied it after a 1-month interval, and they demonstrated superior performance on both acquisition and transfer tasks, relative to the control group. Physical education teachers and coaches should consider using this learning strategy to enhance the learning of closed motor skills.

Set Shifting Training with Categorization Tasks

PubMed Central

Soveri, Anna; Waris, Otto; Laine, Matti

2013-01-01

The very few cognitive training studies targeting an important executive function, set shifting, have reported performance improvements that also generalized to untrained tasks. The present randomized controlled trial extends set shifting training research by comparing previously used cued training with uncued training. A computerized adaptation of the Wisconsin Card Sorting Test was utilized as the training task in a pretest-posttest experimental design involving three groups of university students. One group received uncued training (n = 14), another received cued training (n = 14) and the control group (n = 14) only participated in pre- and posttests. The uncued training group showed posttraining performance increases on their training task, but neither training group showed statistically significant transfer effects. Nevertheless, comparison of effect sizes for transfer effects indicated that our results did not differ significantly from the previous studies. Our results suggest that the cognitive effects of computerized set shifting training are mostly task-specific, and would preclude any robust generalization effects with this training. PMID:24324717

False-belief understanding in frontotemporal dementia and Alzheimer's disease.

PubMed

Fernandez-Duque, Diego; Baird, Jodie A; Black, Sandra E

2009-05-01

The ability to understand other people's behavior in terms of mental states, such as beliefs, desires, and intentions, is central to social interaction. It has been argued that the interpersonal problems of patients with behavioral variant of frontotemporal dementia (FTD-b) are due to a dysfunction of that system. We used first- and second-order false-belief tasks to assess theory-of-mind reasoning in a group of patients with FTD-b and a cognitively matched group of patients with Alzheimer's disease (AD). Both patient groups were equally impaired relative to a healthy elderly group in the cognitively demanding second-order false-belief tasks, revealing that cognitive demands are an important factor in false-belief task performance. Both patient groups reached ceiling performance in the first-order false-belief tasks with minimal cognitive demands, despite the striking difference in their social graces. These results suggest that a conceptual deficit in theory of mind-as measured by the false-belief task-is not at the core of the differences between FTD-b and AD.

When the going gets tough...: Self-motivation is associated with invigoration and fun.

PubMed

Kazén, Miguel; Kuhl, Julius; Leicht, Eva-Maria

2015-11-01

Personality systems interaction (PSI) theory postulates two executive control modes in volitional action: Self-control and self-regulation (self-motivation). Self-control should deplete energy whereas self-motivation should maintain energy and result in invigoration. There were three groups of participants: Self-control, self-motivation, and pretend, who performed a resource-demanding Stroop-Shift and an anagram task. Performance and energy expenditure were examined in each task. Compared to the other groups, the self-motivation group showed increments in blood glucose throughout the experiment, indicating invigoration, and had better performance on the difficult Stroop-Shift task than the self-control group. Additionally, for the self-motivation group anagram performance correlated with less effort and ease of concentration and was moderated by fun in the task. These results are consonant with the predictions of PSI and self-determination theories. It is concluded that self-control depletes resources whereas self-motivation is associated with invigoration in carrying resource-demanding tasks.

Early stage second-language learning improves executive control: evidence from ERP.

PubMed

Sullivan, Margot D; Janus, Monika; Moreno, Sylvain; Astheimer, Lori; Bialystok, Ellen

2014-12-01

A growing body of research has reported a bilingual advantage in performance on executive control tasks, but it is not known at what point in emerging bilingualism these advantages first appear. The present study investigated the effect of early stage second-language training on executive control. Monolingual English-speaking students were tested on a go-nogo task, sentence judgment task, and verbal fluency, before and after 6 months of Spanish instruction. The training group (n = 25) consisted of students enrolled in introductory Spanish and the control group (n = 30) consisted of students enrolled in introductory Psychology. After training, the Spanish group showed larger P3 amplitude on the go-nogo task and smaller P600 amplitude on the judgment task, indicating enhanced performance, with no changes for the control group and no differences between groups on behavioral measures. Results are discussed in terms of neural changes underlying executive control after brief second-language learning. Copyright © 2014 Elsevier Inc. All rights reserved.

Practice makes imperfect: Working memory training can harm recognition memory performance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Matzen, Laura E.; Trumbo, Michael C.; Haass, Michael J.

There is a great deal of debate concerning the benefits of working memory (WM) training and whether that training can transfer to other tasks. Although a consistent finding is that WM training programs elicit a short-term near-transfer effect (i.e., improvement in WM skills), results are inconsistent when considering persistence of such improvement and far transfer effects. In this study, we compared three groups of participants: a group that received WM training, a group that received training on how to use a mental imagery memory strategy, and a control group that received no training. Although the WM training group improved onmore » the trained task, their posttraining performance on nontrained WM tasks did not differ from that of the other two groups. In addition, although the imagery training group’s performance on a recognition memory task increased after training, the WM training group’s performance on the task decreased after training. Participants’ descriptions of the strategies they used to remember the studied items indicated that WM training may lead people to adopt memory strategies that are less effective for other types of memory tasks. Our results indicate that WM training may have unintended consequences for other types of memory performance.« less

Training working memory updating in young adults.

PubMed

Linares, Rocío; Borella, Erika; Lechuga, M Teresa; Carretti, Barbara; Pelegrina, Santiago

2018-05-01

Working memory updating (WMU) is a core mechanism in the human mental architecture and a good predictor of a wide range of cognitive processes. This study analyzed the benefits of two different WMU training procedures, near transfer effects on a working memory measure, and far transfer effects on nonverbal reasoning. Maintenance of any benefits a month later was also assessed. Participants were randomly assigned to: an adaptive training group that performed two numerical WMU tasks during four sessions; a non-adaptive training group that performed the same tasks but on a constant and less demanding level of difficulty; or an active control group that performed other tasks unrelated with working memory. After the training, all three groups showed improvements in most of the tasks, and these benefits were maintained a month later. The gain in one of the two WMU measures was larger for the adaptive and non-adaptive groups than for the control group. This specific gain in a task similar to the one trained would indicate the use of a better strategy for performing the task. Besides this nearest transfer effect, no other transfer effects were found. The adaptability of the training procedure did not produce greater improvements. These results are discussed in terms of the training procedure and the feasibility of training WMU.

Sex differences on a computerized mental rotation task disappear with computer familiarization.

PubMed

Roberts, J E; Bell, M A

2000-12-01

The area of cognitive research that has produced the most consistent sex differences is spatial ability. Particularly, men consistently perform better on mental rotation tasks than do women. This study examined the effects of familiarization with a computer on performance of a computerized two-dimensional mental rotation task. Two groups of college students (N=44) performed the rotation task, with one group performing a color-matching task that allowed them to be familiarized with the computer prior to the rotation task. Among the participants who only performed the rotation task, the 11 men performed better than the 11 women. Among the participants who performed the computer familiarization task before the rotation task, how ever, there were no sex differences on the mental rotation task between the 10 men and 12 women. These data indicate that sex differences on this two-dimensional task may reflect familiarization with the computer, not the mental rotation component of the task. Further research with larger samples and increased range of task difficulty is encouraged.

Performing a secondary executive task with affective stimuli interferes with decision making under risk conditions.

PubMed

Gathmann, Bettina; Pawlikowski, Mirko; Schöler, Tobias; Brand, Matthias

2014-05-01

Previous studies demonstrated that executive functions are crucial for advantageous decision making under risk and that therefore decision making is disrupted when working memory capacity is demanded while working on a decision task. While some studies also showed that emotions can affect decision making under risk, it is unclear how affective processing and executive functions predict decision-making performance in interaction. The current experimental study used a between-subjects design to examine whether affective pictures (positive and negative pictures compared to neutral pictures), included in a parallel executive task (working memory 2-back task), have an impact on decision making under risk as assessed by the Game of Dice Task (GDT). Moreover, the performance GDT plus 2-back task was compared to the performance in the GDT without any additional task (GDT solely). The results show that the performance in the GDT differed between groups (positive, negative, neutral, and GDT solely). The groups with affective pictures, especially those with positive pictures in the 2-back task, showed more disadvantageous decisions in the GDT than the groups with neutral pictures and the group performing the GDT without any additional task. However, executive functions moderated the effect of the affective pictures. Regardless of affective influence, subjects with good executive functions performed advantageously in the GDT. These findings support the assumption that executive functions and emotional processing interact in predicting decision making under risk.

Task specific grip force control in writer's cramp.

PubMed

Schneider, A S; Fürholzer, W; Marquardt, C; Hermsdörfer, J

2014-04-01

Writer's cramp is defined as a task specific focal dystonia generating hypertonic muscle co-contractions during handwriting resulting in impaired writing performance and exaggerated finger force. However, little is known about the generalisation of grip force across tasks others than writing. The aim of the study was to directly compare regulation of grip forces during handwriting with force regulation in other fine-motor tasks in patients and control subjects. Handwriting, lifting and cyclic movements of a grasped object were investigated in 21 patients and 14 controls. The applied forces were registered in all three tasks and compared between groups and tasks. In addition, task-specific measures of fine-motor skill were assessed. As expected, patients generated exaggerated forces during handwriting compared to control subjects. However there were no statistically significant group differences during lifting and cyclic movements. The control group revealed a generalisation of grip forces across manual tasks whereas in patients there was no such correlation. We conclude that increased finger forces during handwriting are a task-specific phenomenon that does not necessarily generalise to other fine-motor tasks. Force control of patients with writer's cramp in handwriting and other fine-motor tasks is characterised by individualised control strategies. Copyright © 2013 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

Effects of task repetition but no transfer of inhibitory control training in healthy adults.

PubMed

Talanow, Tobias; Ettinger, Ulrich

2018-06-01

Executive functions (EFs) comprise the updating, shifting and inhibition dimensions. According to the Unity and Diversity Model, the inhibition dimension is fully accounted for by a general EFs factor. This suggests that training of inhibition should transfer, in part, to updating and shifting. Therefore, we tested the effectiveness of a three-week inhibition training (high-conflict Stroop task) and explored near transfer effects to an untrained inhibition task (antisaccade task) and far transfer effects to untrained tasks demanding task-set shifting (number-letter-task), working memory updating (n-back task) and planning abilities (Stockings of Cambridge task). We employed a randomized pretest/treatment/posttest study design in n = 102 healthy young adults, assigned to an intensive Stroop training (n = 38), an active control condition (n = 34) or no training intervention (n = 30). In the Stroop training group, Stroop performance improved with practice, while performance in the active control group remained unchanged. The Stroop training group showed improvements in overall Stroop task performance from pretest to posttest, but we observed neither near nor far transfer effects. Additionally, specifically stronger gains on incongruent Stroop trials compared to congruent trials were observed in the Stroop training group when color bar trials were excluded from the pretest-posttest-analysis. Generally, there were substantial improvements from pretest to posttest independent of training condition in all transfer tasks. In sum, our data do not support the existence of transfer effects from inhibition training in healthy young adults. Copyright © 2018 Elsevier B.V. All rights reserved.

The effects of mirror therapy with tasks on upper extremity function and self-care in stroke patients.

PubMed

Park, Youngju; Chang, Moonyoung; Kim, Kyeong-Mi; An, Duk-Hyun

2015-05-01

[Purpose] The purpose of this study was to determine the effects of mirror therapy with tasks on upper extremity unction and self-care in stroke patients. [Subjects] Thirty participants were randomly assigned to either an experimental group (n=15) or a control group (n=15). [Methods] Subjects in the experimental group received mirror therapy with tasks, and those in the control group received a sham therapy; both therapies were administered, five times per week for six weeks. The main outcome measures were the Manual Function Test for the paralyzed upper limb and the Functional Independence Measure for self-care performance. [Results] The experimental group had more significant gains in change scores compared with the control group after the intervention. [Conclusion] We consider mirror therapy with tasks to be an effective form of intervention for upper extremity function and self-care in stroke patients.

Effect of task-oriented training and high-variability practice on gross motor performance and activities of daily living in children with spastic diplegia.

PubMed

Kwon, Hae-Yeon; Ahn, So-Yoon

2016-10-01

[Purpose] This study investigates how a task-oriented training and high-variability practice program can affect the gross motor performance and activities of daily living for children with spastic diplegia and provides an effective and reliable clinical database for future improvement of motor performances skills. [Subjects and Methods] This study randomly assigned seven children with spastic diplegia to each intervention group including that of a control group, task-oriented training group, and a high-variability practice group. The control group only received neurodevelopmental treatment for 40 minutes, while the other two intervention groups additionally implemented a task-oriented training and high-variability practice program for 8 weeks (twice a week, 60 min per session). To compare intra and inter-relationships of the three intervention groups, this study measured gross motor performance measure (GMPM) and functional independence measure for children (WeeFIM) before and after 8 weeks of training. [Results] There were statistically significant differences in the amount of change before and after the training among the three intervention groups for the gross motor performance measure and functional independence measure. [Conclusion] Applying high-variability practice in a task-oriented training course may be considered an efficient intervention method to improve motor performance skills that can tune to movement necessary for daily livelihood through motor experience and learning of new skills as well as change of tasks learned in a complex environment or similar situations to high-variability practice.

Designing the Widget: A Group Decision and Negotiation Task

ERIC Educational Resources Information Center

Delise, Lisa A.; Mello, Abby L.

2017-01-01

The Widget design task is an in-class, experiential exercise that affords students the opportunity to develop interpersonal skills in group negotiation. Students engage in new product design in committees of two dyads where one dyad represents Consumer Research and the other represents Strategic Management. Task information creates different…

75 FR 27857 - Aviation Rulemaking Advisory Committee; Transport Airplane and Engine Issue Area-New Task

Federal Register 2010, 2011, 2012, 2013, 2014

2010-05-18

... (autopilot) and performance and handling qualities in icing conditions to improve transport airplane... the existing Avionics Systems Harmonization Working Group. The Task ARAC is initially tasked with... working group will be expected to provide a report that addresses the following low speed alerting...

Idiom Comprehension in Mandarin-Speaking Children

ERIC Educational Resources Information Center

Hsieh, Shelley Ching-Yu; Hsu, Chun-Chieh Natalie

2010-01-01

This study examines the effect of familiarity, context, and linguistic convention on idiom comprehension in Mandarin speaking children. Two experiments (a comprehension task followed by a comprehension task coupled with a metapragmatic task) were administered to test participants in three age groups (6 and 9-year-olds, and an adult control group).…

Effects of Functional-Task Training on Older Adults With Alzheimer's Disease.

PubMed

Pedroso, Renata V; Ayán, Carlos; Fraga, Francisco J; da Silva, Thays M V; Cancela, José M; Santos-Galduròz, Ruth F

2018-01-01

The aim of this study was to verify the effects of functional-task training on cognitive function, activities of daily living (ADL) performance, and functional fitness in community-dwelling older adults with diagnosis of Alzheimer's disease (AD). A total of 57 participants (22 functional-task training group [FTG], 21 social gathering group [SGG], 14 control group [CG]) were recruited. Participants in both intervention groups carried out three 1-hr sessions per week of a functional-task program and social gathering activities for 12 weeks. Significant improvements were observed in executive functions (TMT, t-test, p = .03) in the SGG and in upper limb strength (arm curl, t-test, p = .01) in the FTG. Functional-task training has no significant effect on cognitive function, ADL, and functional fitness among people with AD, although it may contribute to slowing down the process of deterioration this illness causes.

Influence of early rising on performance in tasks requiring attention and memory.

PubMed

Kumaran, V Shankar; Raghavendra, Bhat Ramachandra; Manjunath, Nandi Krishnamurthy

2012-01-01

Rising early in the morning has been a prescribed discipline of ancient Indian tradition. While there are no scientific studies comparing early rising volitionally versus circumstantially, selected studies on the latter (rising forcefully) have shown negative impact on an individual's peroformance. Hence the present study was undertaken to assess the influence of early rising (during Brahma-muhurtha) on tasks requiring attention and the ability to recall. Fifty four normal healthy male volunteers, with ages ranging from 16-22 years from a residential school were selected. They were randomly allocated to two groups (Brahma-muhurtha and control). They were assessed on day 1, day 10 and day 20 of the intervention, using a digit letter substitution task and verbal and spatial memory task. The Brahma-muhurtha group were asked to rise before 4:30 am in the morning based on the traditional Indian astrological calculations, while the control group were allowed to wake up just before 7 am which was their regular timing for waking. Brahma-muhurtha group after 20 days showed a significant improvement in the net scores for digit letter substitution task as well as scores for verbal and spatial memory tasks. The control group also showed an improvement in the memory task but not in the task requiring attentional processes. The present study suggests that rising early in the morning as described in ancient Indian tradition influences the process of attention and can improve the ability to recall.

The effect of cognitive-motor dual task training with the biorescue force platform on cognition, balance and dual task performance in institutionalized older adults: a randomized controlled trial

PubMed Central

Delbroek, Tom; Vermeylen, Wietse; Spildooren, Joke

2017-01-01

[Purpose] This study investigates whether cognition, balance and dual task performance in institutionalized older adults improves by a virtual reality dual task training. [Subjects and Methods] Randomized controlled trial; Twenty institutionalized older adults with mild cognitive impairment (13 female, 7 male; average age, 87.2 ± 5.96 years) were randomized to the intervention (i.e. Virtual reality dual-task training using the BioRescue) or control group (no additional training). The intervention group took part in a 6-week training program while the elderly in the control group maintained their daily activities. Balance was measured with the Instrumented Timed Up-and-Go Test with and without a cognitive task. The Observed Emotion Rating Scale and Intrinsic Motivation Inventory were administered to evaluate the emotions and motivation regarding the exergaming program. [Results] The intervention group improved significantly on the total Timed Up-and-Go duration and the turn-to-sit duration during single-task walking in comparison to the control group who received no additional training. Participants found the virtual reality dual task training pleasant and useful for their concentration, memory and balance. Pleasure and alertness were the two emotions which were mostly seen during the intervention. [Conclusion] The BioRescue is a pleasant and interesting treatment method, well suited for institutionalized older adults in need of lifelong physical therapy. PMID:28744033

Sensitivity of negative subsequent memory and task-negative effects to age and associative memory performance.

PubMed

de Chastelaine, Marianne; Mattson, Julia T; Wang, Tracy H; Donley, Brian E; Rugg, Michael D

2015-07-01

The present fMRI experiment employed associative recognition to investigate the relationships between age and encoding-related negative subsequent memory effects and task-negative effects. Young, middle-aged and older adults (total n=136) were scanned while they made relational judgments on visually presented word pairs. In a later memory test, the participants made associative recognition judgments on studied, rearranged (items studied on different trials) and new pairs. Several regions, mostly localized to the default mode network, demonstrated negative subsequent memory effects in an across age-group analysis. All but one of these regions also demonstrated task-negative effects, although there was no correlation between the size of the respective effects. Whereas negative subsequent memory effects demonstrated a graded attenuation with age, task-negative effects declined markedly between the young and the middle-aged group, but showed no further reduction in the older group. Negative subsequent memory effects did not correlate with memory performance within any age group. By contrast, in the older group only, task-negative effects predicted later memory performance. The findings demonstrate that negative subsequent memory and task-negative effects depend on dissociable neural mechanisms and likely reflect distinct cognitive processes. The relationship between task-negative effects and memory performance in the older group might reflect the sensitivity of these effects to variations in amount of age-related neuropathology. This article is part of a Special Issue entitled SI: Memory. Copyright © 2014 Elsevier B.V. All rights reserved.

Task-irrelevant emotion facilitates face discrimination learning.

PubMed

Lorenzino, Martina; Caudek, Corrado

2015-03-01

We understand poorly how the ability to discriminate faces from one another is shaped by visual experience. The purpose of the present study is to determine whether face discrimination learning can be facilitated by facial emotions. To answer this question, we used a task-irrelevant perceptual learning paradigm because it closely mimics the learning processes that, in daily life, occur without a conscious intention to learn and without an attentional focus on specific facial features. We measured face discrimination thresholds before and after training. During the training phase (4 days), participants performed a contrast discrimination task on face images. They were not informed that we introduced (task-irrelevant) subtle variations in the face images from trial to trial. For the Identity group, the task-irrelevant features were variations along a morphing continuum of facial identity. For the Emotion group, the task-irrelevant features were variations along an emotional expression morphing continuum. The Control group did not undergo contrast discrimination learning and only performed the pre-training and post-training tests, with the same temporal gap between them as the other two groups. Results indicate that face discrimination improved, but only for the Emotion group. Participants in the Emotion group, moreover, showed face discrimination improvements also for stimulus variations along the facial identity dimension, even if these (task-irrelevant) stimulus features had not been presented during training. The present results highlight the importance of emotions for face discrimination learning. Copyright © 2015 Elsevier Ltd. All rights reserved.

Effects of a Supportive Audience on a Handgrip Squeezing Task in Adults

PubMed Central

LEITZELAR, BRIANNA N.; RAZON, SELEN; TOKAC, UMIT; DIERINGER, SHANNON; BOOK, CINDY; JUDGE, LAWRENCE W.

2016-01-01

The role of social facilitation by way of audience effect in select exercise-related variables during an isometric handgrip task was assessed using a mixed design. Fifty three moderately active participants (Mage= 21.76 ± 5.27) were recruited from the Midwestern United States. Participants were randomly assigned to one of two groups: supportive audience or control. Audience members provided positive verbal encouragement to participants in the experimental condition throughout the task performance. Participants in the control group performed the task in the absence of an audience and did not receive any verbal encouragement. Participants provided anxiety ratings pre- and post-task using the State-trait anxiety inventory for adults (STAI). Participants’ ratings of perceived exertion (RPE) and heart rate (HR) were monitored and assessed at 30-second intervals. Upon task completion, sustained effort in the form of time on task was recorded in seconds. A repeated measures analysis of variance (RM ANOVA) revealed that there was a time effect within groups of HR = ( F(2.64, 131.85) = 189.3, p <0.001) and within groups of RPE = (F(2.97, 139.42) = 2189.43 p <0.001). An independent sample T-test revealed significant differences in HR at 0, 30 and 60 seconds between the groups. An independent sample T-test revealed no significant differences in anxiety and RPE between the groups. These results partially support the notion of social facilitation and may have implications for research and practice. PMID:29399254

TU-E-TOUR-I-00: Exhibit Hall Guided Tours-Dosimters for QC in Diagnostic Imaging (Tuesday)

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

Tour Leader: Xia Jiang, Ohio State University, Columbus, OH Tour Guides: Xia Jiang, Ohio State University, Columbus, OH Kevin Little, The University of Chicago, Chicago, IL Christina Sammet, Lurie Children’s Hospital of Chicago, Chicago, IL Participating Vendors: IBA PTW - New York Radcal Corporation RTI Electronics, Inc. Exhibit Hall Guided Tours is a new program launching this year at the Annual Meeting. The Guided Tours are designed to enhance the interaction between meeting attendees and exhibitors. This year’s Imaging Guided Tours are organized around the theme of dosimeters for quality control in diagnostic imaging. Tours will begin with an introductionmore » and background given by Dr. Xia Jiang, the Tour Leader. The introduction will cover the types and properties of different radiation dosimeters used for quality assurance in clinical radiology. Attendees will then break into smaller groups, each lead by an AAPM-member Tour Guide. The tour groups will visit the exhibit booths of vendors who provide appropriate dosimeters, and a vendor representative will give a presentation to the group about their particular product(s). The vendor representatives as well as the Tour Guides will be available to answer questions. Outline: Types and properties of radiation detectors and dosimeters Ionization chamber dosimeters Solid state dosimeters Dosimeter calibration: Primary and secondary standards dosimetry laboratories Instruments for measuring tube voltage and exposure time Vendor presentations will likely cover features and innovations of different dosimeter systems, as well as their practical use. Learning Objectives: Understand the types and properties of different instrumentations used for quality control in diagnostic imaging. Understand the process of dosimeter calibration. Gain familiarity with the latest commercial dosimeter systems from different vendors.« less

WE-C-TOUR-I-00: Exhibit Hall Guided Tours-Dosimters for QC in Diagnostic Imaging (Wednesday)

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

Tour Leader: Xia Jiang, Ohio State University, Columbus, OH Tour Guides: Xia Jiang, Ohio State University, Columbus, OH Kevin Little, The University of Chicago, Chicago, IL Adrien Sanchez, University of Chicago, Chicago, IL Participating Vendors: IBA PTW - New York Radcal Corporation RTI Electronics, Inc. Exhibit Hall Guided Tours is a new program launching this year at the Annual Meeting. The Guided Tours are designed to enhance the interaction between meeting attendees and exhibitors. This year’s Imaging Guided Tours are organized around the theme of dosimeters for quality control in diagnostic imaging. Tours will begin with an introduction and backgroundmore » given by Dr. Xia Jiang, the Tour Leader. The introduction will cover the types and properties of different radiation dosimeters used for quality assurance in clinical radiology. Attendees will then break into smaller groups, each lead by an AAPM-member Tour Guide. The tour groups will visit the exhibit booths of vendors who provide appropriate dosimeters, and a vendor representative will give a presentation to the group about their particular product(s). The vendor representatives as well as the Tour Guides will be available to answer questions. Outline: Types and properties of radiation detectors and dosimeters Ionization chamber dosimeters Solid state dosimeters Dosimeter calibration: Primary and secondary standards dosimetry laboratories Instruments for measuring tube voltage and exposure time Vendor presentations will likely cover features and innovations of different dosimeter systems, as well as their practical use. Learning Objectives: Understand the types and properties of different instrumentations used for quality control in diagnostic imaging. Understand the process of dosimeter calibration. Gain familiarity with the latest commercial dosimeter systems from different vendors.« less

WE-C-TOUR-I-01: Dosimters for QC in Diagnostic Imaging

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jiang, X.

Tour Leader: Xia Jiang, Ohio State University, Columbus, OH Tour Guides: Xia Jiang, Ohio State University, Columbus, OH Kevin Little, The University of Chicago, Chicago, IL Adrien Sanchez, University of Chicago, Chicago, IL Participating Vendors: IBA PTW - New York Radcal Corporation RTI Electronics, Inc. Exhibit Hall Guided Tours is a new program launching this year at the Annual Meeting. The Guided Tours are designed to enhance the interaction between meeting attendees and exhibitors. This year’s Imaging Guided Tours are organized around the theme of dosimeters for quality control in diagnostic imaging. Tours will begin with an introduction and backgroundmore » given by Dr. Xia Jiang, the Tour Leader. The introduction will cover the types and properties of different radiation dosimeters used for quality assurance in clinical radiology. Attendees will then break into smaller groups, each lead by an AAPM-member Tour Guide. The tour groups will visit the exhibit booths of vendors who provide appropriate dosimeters, and a vendor representative will give a presentation to the group about their particular product(s). The vendor representatives as well as the Tour Guides will be available to answer questions. Outline: Types and properties of radiation detectors and dosimeters Ionization chamber dosimeters Solid state dosimeters Dosimeter calibration: Primary and secondary standards dosimetry laboratories Instruments for measuring tube voltage and exposure time Vendor presentations will likely cover features and innovations of different dosimeter systems, as well as their practical use. Learning Objectives: Understand the types and properties of different instrumentations used for quality control in diagnostic imaging. Understand the process of dosimeter calibration. Gain familiarity with the latest commercial dosimeter systems from different vendors.« less

Basic Timing Abilities Stay Intact in Patients with Musician's Dystonia

PubMed Central

van der Steen, M. C.; van Vugt, Floris T.; Keller, Peter E.; Altenmüller, Eckart

2014-01-01

Task-specific focal dystonia is a movement disorder that is characterized by the loss of voluntary motor control in extensively trained movements. Musician's dystonia is a type of task-specific dystonia that is elicited in professional musicians during instrumental playing. The disorder has been associated with deficits in timing. In order to test the hypothesis that basic timing abilities are affected by musician's dystonia, we investigated a group of patients (N = 15) and a matched control group (N = 15) on a battery of sensory and sensorimotor synchronization tasks. Results did not show any deficits in auditory-motor processing for patients relative to controls. Both groups benefited from a pacing sequence that adapted to their timing (in a sensorimotor synchronization task at a stable tempo). In a purely perceptual task, both groups were able to detect a misaligned metronome when it was late rather than early relative to a musical beat. Overall, the results suggest that basic timing abilities stay intact in patients with musician's dystonia. This supports the idea that musician's dystonia is a highly task-specific movement disorder in which patients are mostly impaired in tasks closely related to the demands of actually playing their instrument. PMID:24667273

Learning task affects ERP-correlates of the own-race bias, but not recognition memory performance.

PubMed

Stahl, Johanna; Wiese, Holger; Schweinberger, Stefan R

2010-06-01

People are generally better in recognizing faces from their own ethnic group as opposed to faces from another ethnic group, a finding which has been interpreted in the context of two opposing theories. Whereas perceptual expertise theories stress the role of long-term experience with one's own ethnic group, race feature theories assume that the processing of an other-race-defining feature triggers inferior coding and recognition of faces. The present study tested these hypotheses by manipulating the learning task in a recognition memory test. At learning, one group of participants categorized faces according to ethnicity, whereas another group rated facial attractiveness. Subsequent recognition tests indicated clear and similar own-race biases for both groups. However, ERPs from learning and test phases demonstrated an influence of learning task on neurophysiological processing of own- and other-race faces. While both groups exhibited larger N170 responses to Asian as compared to Caucasian faces, task-dependent differences were seen in a subsequent P2 ERP component. Whereas the P2 was more pronounced for Caucasian faces in the categorization group, this difference was absent in the attractiveness rating group. The learning task thus influences early face encoding. Moreover, comparison with recent research suggests that this attractiveness rating task influences the processes reflected in the P2 in a similar manner as perceptual expertise for other-race faces does. By contrast, the behavioural own-race bias suggests that long-term expertise is required to increase other-race face recognition and hence attenuate the own-race bias. Copyright 2010 Elsevier Ltd. All rights reserved.

Perceptual Grouping Enhances Visual Plasticity

PubMed Central

Mastropasqua, Tommaso; Turatto, Massimo

2013-01-01

Visual perceptual learning, a manifestation of neural plasticity, refers to improvements in performance on a visual task achieved by training. Attention is known to play an important role in perceptual learning, given that the observer's discriminative ability improves only for those stimulus feature that are attended. However, the distribution of attention can be severely constrained by perceptual grouping, a process whereby the visual system organizes the initial retinal input into candidate objects. Taken together, these two pieces of evidence suggest the interesting possibility that perceptual grouping might also affect perceptual learning, either directly or via attentional mechanisms. To address this issue, we conducted two experiments. During the training phase, participants attended to the contrast of the task-relevant stimulus (oriented grating), while two similar task-irrelevant stimuli were presented in the adjacent positions. One of the two flanking stimuli was perceptually grouped with the attended stimulus as a consequence of its similar orientation (Experiment 1) or because it was part of the same perceptual object (Experiment 2). A test phase followed the training phase at each location. Compared to the task-irrelevant no-grouping stimulus, orientation discrimination improved at the attended location. Critically, a perceptual learning effect equivalent to the one observed for the attended location also emerged for the task-irrelevant grouping stimulus, indicating that perceptual grouping induced a transfer of learning to the stimulus (or feature) being perceptually grouped with the task-relevant one. Our findings indicate that no voluntary effort to direct attention to the grouping stimulus or feature is necessary to enhance visual plasticity. PMID:23301100