Dose Calculation Evolution for Internal Organ Irradiation in Humans

NASA Astrophysics Data System (ADS)

Jimenez V., Reina A.

2007-10-01

The International Commission of Radiation Units (ICRU) has established through the years, a discrimination system regarding the security levels on the prescription and administration of doses in radiation treatments (Radiotherapy, Brach therapy, Nuclear Medicine). The first level is concerned with the prescription and posterior assurance of dose administration to a point of interest (POI), commonly located at the geometrical center of the region to be treated. In this, the effects of radiation around that POI, is not a priority. The second level refers to the dose specifications in a particular plane inside the patient, mostly the middle plane of the lesion. The dose is calculated to all the structures in that plane regardless if they are tumor or healthy tissue. In this case, the dose is not represented by a point value, but by level curves called "isodoses" as in a topographic map, so you can assure the level of doses to this particular plane, but it also leave with no information about how this values go thru adjacent planes. This is why the third level is referred to the volumetrical description of doses so these isodoses construct now a volume (named "cloud") that give us better assurance about tissue irradiation around the volume of the lesion and its margin (sub clinical spread or microscopic illness). This work shows how this evolution has resulted, not only in healthy tissue protection improvement but in a rise of tumor control, quality of life, better treatment tolerance and minimum permanent secuelae.

Patient dosimetry audit for establishing local diagnostic reference levels for nuclear medicine CT.

PubMed

Gardner, Matthew; Katsidzira, Ngonidzashe M; Ross, Erin; Larkin, Elizabeth A

2017-03-01

To establish a system for patient dosimetry audit and setting of local diagnostic reference levels (LDRLs) for nuclear medicine (NM) CT. Computed radiological information system (CRIS) data were matched with NM paper records, which provided the body region and dose mode for NMCT carried out at a large UK hospital. It was necessary to divide data in terms of the NM examination type, body region and dose mode. The mean and standard deviation dose-length products (DLPs) for common NMCT examinations were then calculated and compared with the proposed National Diagnostic Reference Levels (NDRLs). Only procedures which have 10 or more patients will be used to suggest LDRLs. For most examinations, the mean DLPs do not exceed the proposed NDRLs. The bone single-photon emission CT/CT lumbar spine data clearly show the need to divide data according to the purpose of the scan (dose mode), with mean (±standard error) DLPs ranging from 51 ± 5 mGy cm (low dose) to 1086 ± 124 mGy cm (metal dose). A system for NMCT patient dose audit has been developed, but there are non-trivial challenges which make the process labour intensive. These include limited information provided by CRIS downloads, dependence on paper records and limited number of examinations available owing to the need to subdivide data. Advances in knowledge: This article demonstrates that a system can be developed for NMCT patient dose audit, but also highlights the challenges associated with such audit, which may not be encountered with more routine audit of radiology CT.

DEVELOPMENT OF TOXICITY REFERENCE VALUES FOR ECOLOGICAL SOIL SCREENING LEVELS (ECO-SSLS) FOR TERRESTRIAL WILDLIFE

EPA Science Inventory

Ecological Soil Screening Levels (Eco-SSLs) protective of terrestrial wildlife were developed by the USEPA Superfund. The wildlife Eco-SSL is the soil contaminant concentration where the Effect Dose (TRV) and Exposure Dose are equal (amount of contaminant in the diet that is take...

PAEDIATRIC CT EXPOSURE PRACTICE IN THE COUNTY OF RIO DE JANEIRO: THE NEED TO ESTABLISH DIAGNOSTIC REFERENCE LEVELS.

PubMed

de Jesus, Fillipe M; Magalhães, Luis A G; Kodlulovich, Simone

2016-11-01

A pilot study of dose indicators in paediatric computed tomography (CT) was conducted to prove the need to establish diagnostic reference levels (DRLs) for the county of Rio de Janeiro. The dose descriptors were estimated from the beam dosimetry by applying the protocols used in each examination. The total patient sample included 279 children. Regarding the comparison of the dose-length product values among the hospitals, the high-resolution chest CT scans were distinguished among the three types of examinations, due to the discrepancies of 1148 % (1-5 y age group) and 2248 % (5-10 y age group) presented in Hospital A's dose-length product values relative to Hospital D's dose-length product values. The results showed that without DRL, the dose variation can be significant between hospitals in the same county for the same age group in the same examination. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Is patient size important in dose determination and optimization in cardiology?

NASA Astrophysics Data System (ADS)

Reay, J.; Chapple, C. L.; Kotre, C. J.

2003-12-01

Patient dose determination and optimization have become more topical in recent years with the implementation of the Medical Exposures Directive into national legislation, the Ionising Radiation (Medical Exposure) Regulations. This legislation incorporates a requirement for new equipment to provide a means of displaying a measure of patient exposure and introduces the concept of diagnostic reference levels. It is normally assumed that patient dose is governed largely by patient size; however, in cardiology, where procedures are often very complex, the significance of patient size is less well understood. This study considers over 9000 cardiology procedures, undertaken throughout the north of England, and investigates the relationship between patient size and dose. It uses simple linear regression to calculate both correlation coefficients and significance levels for data sorted by both room and individual clinician for the four most common examinations, left ventrical and/or coronary angiography, single vessel stent insertion and single vessel angioplasty. This paper concludes that the correlation between patient size and dose is weak for the procedures considered. It also illustrates the use of an existing method for removing the effect of patient size from dose survey data. This allows typical doses and, therefore, reference levels to be defined for the purposes of dose optimization.

Commissioning and comprehensive evaluation of the ArcCHECK cylindrical diode array for VMAT pretreatment delivery QA.

PubMed

Chaswal, Vibha; Weldon, Michael; Gupta, Nilendu; Chakravarti, Arnab; Rong, Yi

2014-07-08

We present commissioning and comprehensive evaluation for ArcCHECK as a QA equipment for volumetric-modulated arc therapy (VMAT), using the 6 MV photon beam with and without the flattening filter, and the SNC patient software (version 6.2). In addition to commissioning involving absolute dose calibration, array calibration, and PMMA density verification, ArcCHECK was evaluated for its response dependency on linac dose rate, instantaneous dose rate, radiation field size, beam angle, and couch insertion. Scatter dose characterization, consistency and symmetry of response, and dosimetry accuracy evaluation for fixed aperture arcs and clinical VMAT patient plans were also investigated. All the evaluation tests were performed with the central plug inserted and the homogeneous PMMA density value. Results of gamma analysis demonstrated an overall agreement between ArcCHECK-measured and TPS-calculated reference doses. The diode based field size dependency was found to be within 0.5% of the reference. The dose rate-based dependency was well within 1% of the TPS reference, and the angular dependency was found to be ± 3% of the reference, as tested for BEV angles, for both beams. Dosimetry of fixed arcs, using both narrow and wide field widths, resulted in clinically acceptable global gamma passing rates on the 3%/3mm level and 10% threshold. Dosimetry of narrow arcs showed an improvement over published literature. The clinical VMAT cases demonstrated high level of dosimetry accuracy in gamma passing rates.

Variability in CT lung-nodule quantification: Effects of dose reduction and reconstruction methods on density and texture based features.

PubMed

Lo, P; Young, S; Kim, H J; Brown, M S; McNitt-Gray, M F

2016-08-01

To investigate the effects of dose level and reconstruction method on density and texture based features computed from CT lung nodules. This study had two major components. In the first component, a uniform water phantom was scanned at three dose levels and images were reconstructed using four conventional filtered backprojection (FBP) and four iterative reconstruction (IR) methods for a total of 24 different combinations of acquisition and reconstruction conditions. In the second component, raw projection (sinogram) data were obtained for 33 lung nodules from patients scanned as a part of their clinical practice, where low dose acquisitions were simulated by adding noise to sinograms acquired at clinical dose levels (a total of four dose levels) and reconstructed using one FBP kernel and two IR kernels for a total of 12 conditions. For the water phantom, spherical regions of interest (ROIs) were created at multiple locations within the water phantom on one reference image obtained at a reference condition. For the lung nodule cases, the ROI of each nodule was contoured semiautomatically (with manual editing) from images obtained at a reference condition. All ROIs were applied to their corresponding images reconstructed at different conditions. For 17 of the nodule cases, repeat contours were performed to assess repeatability. Histogram (eight features) and gray level co-occurrence matrix (GLCM) based texture features (34 features) were computed for all ROIs. For the lung nodule cases, the reference condition was selected to be 100% of clinical dose with FBP reconstruction using the B45f kernel; feature values calculated from other conditions were compared to this reference condition. A measure was introduced, which the authors refer to as Q, to assess the stability of features across different conditions, which is defined as the ratio of reproducibility (across conditions) to repeatability (across repeat contours) of each feature. The water phantom results demonstrated substantial variability among feature values calculated across conditions, with the exception of histogram mean. Features calculated from lung nodules demonstrated similar results with histogram mean as the most robust feature (Q ≤ 1), having a mean and standard deviation Q of 0.37 and 0.22, respectively. Surprisingly, histogram standard deviation and variance features were also quite robust. Some GLCM features were also quite robust across conditions, namely, diff. variance, sum variance, sum average, variance, and mean. Except for histogram mean, all features have a Q of larger than one in at least one of the 3% dose level conditions. As expected, the histogram mean is the most robust feature in their study. The effects of acquisition and reconstruction conditions on GLCM features vary widely, though trending toward features involving summation of product between intensities and probabilities being more robust, barring a few exceptions. Overall, care should be taken into account for variation in density and texture features if a variety of dose and reconstruction conditions are used for the quantification of lung nodules in CT, otherwise changes in quantification results may be more reflective of changes due to acquisition and reconstruction conditions than in the nodule itself.

ADVERSE HEALTH EFFECTS FROM ENVIRONMENTAL MANGANESE EXPOSURE.

EPA Science Inventory

The ubiquitous element, manganese (Mn), is an essential nutrient, but toxic at excessive exposure levels. Therefore, the US EPA set guideline levels for Mn exposure through inhalation (reference concentration-RfC=0.05 ?g/m3) and ingestion (reference dose-RfD=0.14 mg/kg/day (10 mg...

Effect of radiation dose reduction and iterative reconstruction on computer-aided detection of pulmonary nodules: Intra-individual comparison.

PubMed

Den Harder, Annemarie M; Willemink, Martin J; van Hamersvelt, Robbert W; Vonken, Evert-Jan P A; Milles, Julien; Schilham, Arnold M R; Lammers, Jan-Willem; de Jong, Pim A; Leiner, Tim; Budde, Ricardo P J

2016-02-01

To evaluate the effect of radiation dose reduction and iterative reconstruction (IR) on the performance of computer-aided detection (CAD) for pulmonary nodules. In this prospective study twenty-five patients were included who were scanned for pulmonary nodule follow-up. Image acquisition was performed at routine dose and three reduced dose levels in a single session by decreasing mAs-values with 45%, 60% and 75%. Tube voltage was fixed at 120 kVp for patients ≥ 80 kg and 100 kVp for patients < 80 kg. Data were reconstructed with filtered back projection (FBP), iDose(4) (levels 1,4,6) and IMR (levels 1-3). All noncalcified solid pulmonary nodules ≥ 4 mm identified by two radiologists in consensus served as the reference standard. Subsequently, nodule volume was measured with CAD software and compared to the reference consensus. The numbers of true-positives, false-positives and missed pulmonary nodules were evaluated as well as the sensitivity. Median effective radiation dose was 2.2 mSv at routine dose and 1.2, 0.9 and 0.6 mSv at respectively 45%, 60% and 75% reduced dose. A total of 28 pulmonary nodules were included. With FBP at routine dose, 89% (25/28) of the nodules were correctly identified by CAD. This was similar at reduced dose levels with FBP, iDose(4) and IMR. CAD resulted in a median number of false-positives findings of 11 per scan with FBP at routine dose (93% of the CAD marks) increasing to 15 per scan with iDose(4) (95% of the CAD marks) and 26 per scan (96% of the CAD marks) with IMR at the lowest dose level. CAD can identify pulmonary nodules at submillisievert dose levels with FBP, hybrid and model-based IR. However, the number of false-positive findings increased using hybrid and especially model-based IR at submillisievert dose while dose reduction did not affect the number of false-positives with FBP. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Reference dosimetry using radiochromic film

PubMed Central

Girard, Frédéric; Bouchard, Hugo

2012-01-01

The objectives of this study are to identify and quantify factors that influence radiochromic film dose response and to determine whether such films are suitable for reference dosimetry. The influence of several parameters that may introduce systematic dose errors when performing reference dose measurements were investigated. The effect of the film storage temperature was determined by comparing the performance of three lots of GAFCHROMIC EBT2 films stored at either 4°C or room temperature. The effect of high (>80%) or low (<20%) relative humidity was also determined. Doses measured in optimal conditions with EBT and EBT2 films were then compared with an A12 ionization chamber measurement. Intensity‐modulated radiation therapy quality controls using EBT2 films were also performed in reference dose. The results obtained using reference dose measurements were compared with those obtained using relative dose measurements. Storing the film at 4°C improves the stability of the film over time, but does not eliminate the noncatalytic film development, seen as a rise in optical density over time in the absence of radiation. Relative humidity variations ranging from 80% to 20% have a strong impact on the optical density and could introduce dose errors of up to 15% if the humidity were not controlled during the film storage period. During the scanning procedure, the film temperature influences the optical density that is measured. When controlling for these three parameters, the dose differences between EBT or EBT2 and the A12 chamber are found to be within ±4% (2σ level) over a dose range of 20–350 cGy. Our results also demonstrate the limitation of the Anisotropic Analytical Algorithm for dose calculation of highly modulated treatment plans. PACS numbers: 87.55.Qr; 87.56.Fc PMID:23149793

Patient radiation doses in interventional cardiology in the U.S.: Advisory data sets and possible initial values for U.S. reference levels

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

Miller, Donald L.; Hilohi, C. Michael; Spelic, David C.

2012-10-15

Purpose: To determine patient radiation doses from interventional cardiology procedures in the U.S and to suggest possible initial values for U.S. benchmarks for patient radiation dose from selected interventional cardiology procedures [fluoroscopically guided diagnostic cardiac catheterization and percutaneous coronary intervention (PCI)]. Methods: Patient radiation dose metrics were derived from analysis of data from the 2008 to 2009 Nationwide Evaluation of X-ray Trends (NEXT) survey of cardiac catheterization. This analysis used deidentified data and did not require review by an IRB. Data from 171 facilities in 30 states were analyzed. The distributions (percentiles) of radiation dose metrics were determined for diagnosticmore » cardiac catheterizations, PCI, and combined diagnostic and PCI procedures. Confidence intervals for these dose distributions were determined using bootstrap resampling. Results: Percentile distributions (advisory data sets) and possible preliminary U.S. reference levels (based on the 75th percentile of the dose distributions) are provided for cumulative air kerma at the reference point (K{sub a,r}), cumulative air kerma-area product (P{sub KA}), fluoroscopy time, and number of cine runs. Dose distributions are sufficiently detailed to permit dose audits as described in National Council on Radiation Protection and Measurements Report No. 168. Fluoroscopy times are consistent with those observed in European studies, but P{sub KA} is higher in the U.S. Conclusions: Sufficient data exist to suggest possible initial benchmarks for patient radiation dose for certain interventional cardiology procedures in the U.S. Our data suggest that patient radiation dose in these procedures is not optimized in U.S. practice.« less

Commissioning and comprehensive evaluation of the ArcCHECK cylindrical diode array for VMAT pretreatment delivery QA

PubMed Central

Chaswal, Vibha; Weldon, Michael; Gupta, Nilendu; Chakravarti, Arnab

2014-01-01

We present commissioning and comprehensive evaluation for ArcCHECK as a QA equipment for volumetric‐modulated arc therapy (VMAT), using the 6 MV photon beam with and without the flattening filter, and the SNC patient software (version 6.2). In addition to commissioning involving absolute dose calibration, array calibration, and PMMA density verification, ArcCHECK was evaluated for its response dependency on linac dose rate, instantaneous dose rate, radiation field size, beam angle, and couch insertion. Scatter dose characterization, consistency and symmetry of response, and dosimetry accuracy evaluation for fixed aperture arcs and clinical VMAT patient plans were also investigated. All the evaluation tests were performed with the central plug inserted and the homogeneous PMMA density value. Results of gamma analysis demonstrated an overall agreement between ArcCHECK‐measured and TPS‐calculated reference doses. The diode based field size dependency was found to be within 0.5% of the reference. The dose rate‐based dependency was well within 1% of the TPS reference, and the angular dependency was found to be ± 3% of the reference, as tested for BEV angles, for both beams. Dosimetry of fixed arcs, using both narrow and wide field widths, resulted in clinically acceptable global gamma passing rates on the 3%/3 mm level and 10% threshold. Dosimetry of narrow arcs showed an improvement over published literature. The clinical VMAT cases demonstrated high level of dosimetry accuracy in gamma passing rates. PACS numbers: 87.56.Fc, 87.55.kh, 87.55.Qr PMID:25207411

PROPOSALS FOR THE ESTABLISHMENT OF NATIONAL DIAGNOSTIC REFERENCE LEVELS FOR RADIOGRAPHY FOR ADULT PATIENTS BASED ON REGIONAL DOSE SURVEYS IN RUSSIAN FEDERATION.

PubMed

Vodovatov, A V; Balonov, M I; Golikov, V Yu; Shatsky, I G; Chipiga, L A; Bernhardsson, C

2017-04-01

In 2009-2014, dose surveys aimed to collect adult patient data and parameters of most common radiographic examinations were performed in six Russian regions. Typical patient doses were estimated for the selected examinations both in entrance surface dose and in effective dose. 75%-percentiles of typical patient effective dose distributions were proposed as preliminary regional diagnostic reference levels (DRLs) for radiography. Differences between the 75%-percentiles of regional typical patient dose distributions did not exceed 30-50% for the examinations with standardized clinical protocols (skull, chest and thoracic spine) and a factor of 1.5 for other examinations. Two different approaches for establishing national DRLs were evaluated: as a 75%-percentile of a pooled regional sample of patient typical doses (pooled method) and as a median of 75%-percentiles of regional typical patient dose distributions (median method). Differences between pooled and median methods for effective dose did not exceed 20%. It was proposed to establish Russian national DRLs in effective dose using a pooled method. In addition, the local authorities were granted an opportunity to establish regional DRLs if the local radiological practice and typical patient dose distributions are significantly different. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Bulgarian experience in the establishment of reference dose levels and implementation of a quality control system in diagnostic radiology.

PubMed

Vassileva, J; Dimov, A; Slavchev, A; Karadjov, A

2005-01-01

Results from a Bulgarian patient dose survey in diagnostic radiology are presented. Reference levels for entrance surface dose (ESD) were 0.9 mGy for chest radiography (PA), 30 mGy for lumbar spine (Lat), 10 mGy for pelvis, 5 mGy for skull (AP), 3 mGy for skull (Lat) and 13 mGy for mammography. Quality control (QC) programmes were proposed for various areas of diagnostic radiology. Film processing QC warranted special attention. Proposed QC programmes included parameters to be tested, level of expertise needed and two action levels: remedial and suspension. Programmes were tested under clinical conditions to assess initial results and draw conclusions for further QC system development. On the basis of international experience, measurement protocols were developed for all parameters tested. QC equipment was provided as part of the PHARE project. A future problem for QC programme implementation may be the small number of medical physics experts in diagnostic radiology.

Evidence of dose saving in routine CT practice using iterative reconstruction derived from a national diagnostic reference level survey.

PubMed

Thomas, P; Hayton, A; Beveridge, T; Marks, P; Wallace, A

2015-09-01

To assess the influence and significance of the use of iterative reconstruction (IR) algorithms on patient dose in CT in Australia. We examined survey data submitted to the Australian Radiation Protection and Nuclear Safety Agency (ARPANSA) National Diagnostic Reference Level Service (NDRLS) during 2013 and 2014. We compared median survey dose metrics with categorization by scan region and use of IR. The use of IR results in a reduction in volume CT dose index of between 17% and 44% and a reduction in dose-length product of between 14% and 34% depending on the specific scan region. The reduction was highly significant (p < 0.001, Wilcoxon rank-sum test) for all six scan regions included in the NDRLS. Overall, 69% (806/1167) of surveys included in the analysis used IR. The use of IR in CT is achieving dose savings of 20-30% in routine practice in Australia. IR appears to be widely used by participants in the ARPANSA NDRLS with approximately 70% of surveys submitted employing this technique. This study examines the impact of the use of IR on patient dose in CT on a national scale.

PERCEPTION OF MERCURY RISK INFORMATION

EPA Science Inventory

Approximately 8% of American women have blood Mercury levels exceeding the EPA reference dose (a dose below which symptoms would be unlikely). The children of these women are at risk of neurological deficits (lower IQ scores) primarily because of the mother's consumption of conta...

Estimation of skin entrance doses (SEDs) for common medical X-ray diagnostic examinations in India and proposed diagnostic reference levels (DRLs).

PubMed

Sonawane, A U; Shirva, V K; Pradhan, A S

2010-02-01

Skin entrance doses (SEDs) were estimated by carrying out measurements of air kerma from 101 X-ray machines installed in 45 major and selected hospitals in the country by using a silicon detector-based dose Test-O-Meter. 1209 number of air kerma measurements of diagnostic projections for adults have been analysed for seven types of common diagnostic examinations, viz. chest (AP, PA, LAT), lumbar spine (AP, LAT), thoracic spine (AP, LAT), abdomen (AP), pelvis (AP), hip joints (AP) and skull (PA, LAT) for different film-screen combinations. The values of estimated diagnostic reference levels (DRLs) (third quartile values of SEDs) were compared with guidance levels/DRLs of doses published by the IAEA-BSS-Safety Series No. 115, 1996; HPA (NRPB) (2000 and 2005), UK; CRCPD/CDRH (USA), European Commission and other national values. The values of DRLs obtained in this study are comparable with the values published by the IAEA-BSS-115 (1996); HPA (NRPB) (2000 and 2005) UK; EC and CRCPD/CDRH, USA including values obtained in previous studies in India.

MO-E-18A-01: Imaging: Best Practices In Pediatric Imaging

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

Willis, C; Strauss, K; MacDougall, R

This imaging educational program will focus on solutions to common pediatric imaging challenges. The speakers will present collective knowledge on best practices in pediatric imaging from their experience at dedicated children's hospitals. Areas of focus will include general radiography, the use of manual and automatic dose management in computed tomography, and enterprise-wide radiation dose management in the pediatric practice. The educational program will begin with a discussion of the complexities of exposure factor control in pediatric projection radiography. Following this introduction will be two lectures addressing the challenges of computed tomography (CT) protocol optimization in the pediatric population. The firstmore » will address manual CT protocol design in order to establish a managed radiation dose for any pediatric exam on any CT scanner. The second CT lecture will focus on the intricacies of automatic dose modulation in pediatric imaging with an emphasis on getting reliable results in algorithmbased technique selection. The fourth and final lecture will address the key elements needed to developing a comprehensive radiation dose management program for the pediatric environment with particular attention paid to new regulations and obligations of practicing medical physicists. Learning Objectives: To understand how general radiographic techniques can be optimized using exposure indices in order to improve pediatric radiography. To learn how to establish diagnostic dose reference levels for pediatric patients as a function of the type of examination, patient size, and individual design characteristics of the CT scanner. To learn how to predict the patient's radiation dose prior to the exam and manually adjust technique factors if necessary to match the patient's dose to the department's established dose reference levels. To learn how to utilize manufacturer-provided automatic dose modulation technology to consistently achieve patient doses within the department's established size-based diagnostic reference range. To understand the key components of an enterprise-wide pediatric dose management program that integrates the expanding responsibilities of medial physicists in the new era of dose monitoring.« less

DIFFUSION AND PERCEPTION OF MERCURY RISK INFORMATION

EPA Science Inventory

Approximately 8% of American women have blood Mercury levels exceeding the EPA reference dose (a dose below which symptoms would be unlikely). The children of these women are at risk of neurological deficits (lower IQ scores) primarily because of the mother’s consumption of...

Dosimetry and image quality assessment in a direct radiography system

PubMed Central

Oliveira, Bruno Beraldo; de Oliveira, Marcio Alves; Paixão, Lucas; Teixeira, Maria Helena Araújo; Nogueira, Maria do Socorro

2014-01-01

Objective To evaluate the mean glandular dose with a solid state detector and the image quality in a direct radiography system, utilizing phantoms. Materials and Methods Irradiations were performed with automatic exposure control and polymethyl methacrylate slabs with different thicknesses to calculate glandular dose values. The image quality was evaluated by means of the structures visualized on the images of the phantoms. Results Considering the uncertainty of the measurements, the mean glandular dose results are in agreement with the values provided by the equipment and with internationally adopted reference levels. Results obtained from images of the phantoms were in agreement with the reference values. Conclusion The present study contributes to verify the equipment conformity as regards dose values and image quality. PMID:25741119

RISK PERCEPTION AND DIFFUSION OF MERCURY RISK INFORMATION

EPA Science Inventory

The most recent NHANES data reveals that approximately 8% of American women have blood Mercury levels exceeding the EPA reference dose (a dose below which symptoms would be unlikely). The children of these women are at risk of neurological deficits (lower IQ scores) primarily bec...

Assessment of an organ-based tube current modulation in thoracic computed tomography.

PubMed

Matsubara, Kosuke; Sugai, Mai; Toyoda, Asami; Koshida, Haruka; Sakuta, Keita; Takata, Tadanori; Koshida, Kichiro; Iida, Hiroji; Matsui, Osamu

2012-03-08

Recently, specific computed tomography (CT) scanners have been equipped with organ-based tube current modulation (TCM) technology. It is possible that organ-based TCM will replace the conventional dose-reduction technique of reducing the effective milliampere-second. The aim of this study was to determine if organ-based TCM could reduce radiation exposure to the breasts without compromising the image uniformity and beam hardening effect in thoracic CT examinations. Breast and skin radiation doses and the absorbed radiation dose distribution within a single section were measured with an anthropomorphic phantom and radiophotoluminescent glass dosimeters using four approaches to thoracic CT (reference, organ-based TCM, copper shielding, and the combination of the above two techniques, hereafter referred to as the combination technique). The CT value and noise level were measured using the same calibration phantom. Organ-based TCM and copper shielding reduced radiation doses to the breast by 23.7% and 21.8%, respectively. However, the CT value increased, especially in the anterior region, using copper shielding. In contrast, the CT value and noise level barely increased using organ-based TCM. The combination technique reduced the radiation dose to the breast by 38.2%, but greatly increased the absorbed radiation dose from the central to the posterior regions. Moreover, the CT value increased in the anterior region and the noise level increased by more than 10% in the entire region. Therefore, organ-based TCM can reduce radiation doses to breasts with only small increases in noise levels, making it preferable for specific groups of patients, such as children and young women.

DETERMINATION OF NATIONAL DIAGNOSTIC REFERENCE LEVELS IN COMPUTED TOMOGRAPHY EXAMINATIONS OF IRAN BY A NEW QUALITY CONTROL-BASED DOSE SURVEY METHOD.

PubMed

Sohrabi, Mehdi; Parsi, Masoumeh; Mianji, Fereidoun

2018-05-01

National diagnostic reference levels (NDRLs) of Iran were determined for the four most common CT examinations including head, sinus, chest and abdomen/pelvis. A new 'quality control (QC)-based dose survey method', as developed by us, was applied to 157 CT scanners in Iran (2014-15) with different slice classes, models and geographic spread across the country. The NDRLs for head, sinus, chest and abdomen/pelvis examinations are 58, 29, 12 and 14 mGy for CTDIVol and 750, 300, 300 and 650 mGy.cm for DLP, respectively. The 'QC-based dose survey method' was further proven that it is a simple, accurate and practical method for a time and cost-effective NDRLs determination. One effective approach for optimization of the CT examination protocols at the national level is the provision of an adequate standardized training of the radiologists, technicians and medical physicists on the patient radiation protection principles and implementation of the DRL concept in clinical practices.

Implementation of Size-Dependent Local Diagnostic Reference Levels for CT Angiography.

PubMed

Boere, Hub; Eijsvoogel, Nienke G; Sailer, Anna M; Wildberger, Joachim E; de Haan, Michiel W; Das, Marco; Jeukens, Cecile R L P N

2018-05-01

Diagnostic reference levels (DRLs) are established for standard-sized patients; however, patient dose in CT depends on patient size. The purpose of this study was to introduce a method for setting size-dependent local diagnostic reference levels (LDRLs) and to evaluate these LDRLs in comparison with size-independent LDRLs and with respect to image quality. One hundred eighty-four aortic CT angiography (CTA) examinations performed on either a second-generation or third-generation dual-source CT scanner were included; we refer to the second-generation dual-source CT scanner as "CT1" and the third-generation dual-source CT scanner as "CT2." The volume CT dose index (CTDI vol ) and patient diameter (i.e., the water-equivalent diameter) were retrieved by dose-monitoring software. Size-dependent DRLs based on a linear regression of the CTDI vol versus patient size were set by scanner type. Size-independent DRLs were set by the 5th and 95th percentiles of the CTDI vol values. Objective image quality was assessed using the signal-to-noise ratio (SNR), and subjective image quality was assessed using a 4-point Likert scale. The CTDI vol depended on patient size and scanner type (R 2 = 0.72 and 0.78, respectively; slope = 0.05 and 0.02 mGy/mm; p < 0.001). Of the outliers identified by size-independent DRLs, 30% (CT1) and 67% (CT2) were adequately dosed when considering patient size. Alternatively, 30% (CT1) and 70% (CT2) of the outliers found with size-dependent DRLs were not identified using size-independent DRLs. A negative correlation was found between SNR and CTDI vol (R 2 = 0.36 for CT1 and 0.45 for CT2). However, all outliers had a subjective image quality score of sufficient or better. We introduce a method for setting size-dependent LDRLs in CTA. Size-dependent LDRLs are relevant for assessing the appropriateness of the radiation dose for an individual patient on a specific CT scanner.

Developing patient-specific dose protocols for a CT scanner and exam using diagnostic reference levels.

PubMed

Strauss, Keith J

2014-10-01

The management of image quality and radiation dose during pediatric CT scanning is dependent on how well one manages the radiographic techniques as a function of the type of exam, type of CT scanner, and patient size. The CT scanner's display of expected CT dose index volume (CTDIvol) after the projection scan provides the operator with a powerful tool prior to the patient scan to identify and manage appropriate CT techniques, provided the department has established appropriate diagnostic reference levels (DRLs). This paper provides a step-by-step process that allows the development of DRLs as a function of type of exam, of actual patient size and of the individual radiation output of each CT scanner in a department. Abdomen, pelvis, thorax and head scans are addressed. Patient sizes from newborns to large adults are discussed. The method addresses every CT scanner regardless of vendor, model or vintage. We cover adjustments to techniques to manage the impact of iterative reconstruction and provide a method to handle all available voltages other than 120 kV. This level of management of CT techniques is necessary to properly monitor radiation dose and image quality during pediatric CT scans.

COMPUTATIONAL MODELING OF SIGNALING PATHWAYS MEDIATING CELL CYCLE AND APOPTOTIC RESPONSES TO IONIZING RADIATION MEDIATED DNA DAMAGE

EPA Science Inventory

Demonstrated of the use of a computational systems biology approach to model dose response relationships. Also discussed how the biologically motivated dose response models have only limited reference to the underlying molecular level. Discussed the integration of Computational S...

Sci-Fri AM: MRI and Diagnostic Imaging - 02: Quality Improvement: Diagnostic Reference Levels for Interior Health CT exams – L-Spine, Chest/Abdomen/pelvis, Abdomen/Pelvis, Head

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

Bjarnason, Thorarin

Diagnostic Reference Levels are used to optimize patient dose and image quality in the clinical setting. It is assumed that the majority of exams are of diagnostic quality, or the radiologists would request protocol adjustments. By investigating the dose indicator distributions from all scanners, the upper DRL can be set to the 75th percentile of the distribution and a lower DRL can be set to the 10th percentile. Scanners using doses consistently outside the upper/lower DRL range can be adjusted accordingly. 11 CT scanners, all contributing to the American College of Radiology Dose Index Registry (ACR DIR) were used inmore » this study. Dose indicator data were compiled from the ACR DIR data and local DRLs established. Scanners with median doses outside the upper/lower DRL were followed-up with. Using effective dose and exam volumes, collective dose was determined before and after protocol adjustments to evaluate the effect of this quality improvement effort. The quality initiative is complete for L-spine and Chest/Abdomen/Pelvis exams and only initial surveys were completed for Head and Abdomen/Pelvis examsg. Median Scanner Dose reductions were 8.8 and 4.9 % for L-spine and Chest/Abdomen/Pelvis exams, respectively, resulting with collective dose reductions of 0.7 and 3.2 person•Sv/yr. Follow-up is ongoing for Abdomen/Pelvis and Head exams.« less

Radiological protection from radioactive waste management in existing exposure situations resulting from a nuclear accident.

PubMed

Sugiyama, Daisuke; Hattori, Takatoshi

2013-01-01

In environmental remediation after nuclear accidents, radioactive wastes have to be appropriately managed in existing exposure situations with contamination resulting from the emission of radionuclides by such accidents. In this paper, a framework of radiation protection from radioactive waste management in existing exposure situations for application to the practical and reasonable waste management in contaminated areas, referring to related ICRP recommendations was proposed. In the proposed concept, intermediate reference levels for waste management are adopted gradually according to the progress of the reduction in the existing ambient dose in the environment on the basis of the principles of justification and optimisation by taking into account the practicability of the management of radioactive waste and environmental remediation. It is essential to include the participation of relevant stakeholders living in existing exposure situations in the selection of reference levels for the existing ambient dose and waste management.

Radiological protection from radioactive waste management in existing exposure situations resulting from a nuclear accident

PubMed Central

Sugiyama, Daisuke; Hattori, Takatoshi

2013-01-01

In environmental remediation after nuclear accidents, radioactive wastes have to be appropriately managed in existing exposure situations with contamination resulting from the emission of radionuclides by such accidents. In this paper, a framework of radiation protection from radioactive waste management in existing exposure situations for application to the practical and reasonable waste management in contaminated areas, referring to related ICRP recommendations was proposed. In the proposed concept, intermediate reference levels for waste management are adopted gradually according to the progress of the reduction in the existing ambient dose in the environment on the basis of the principles of justification and optimisation by taking into account the practicability of the management of radioactive waste and environmental remediation. It is essential to include the participation of relevant stakeholders living in existing exposure situations in the selection of reference levels for the existing ambient dose and waste management. PMID:22719047

Using physiologically based pharmacokinetic modeling to address nonlinear kinetics and changes in rodent physiology and metabolism due to aging and adaptation in deriving reference values for propylene glycol methyl ether and propylene glycol methyl ether acetate.

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

Kirman, C R.; Sweeney, Lisa M.; Corley, Rick A.

2005-04-01

Reference values, including an oral reference dose (RfD) and an inhalation reference concentration (RfC), were derived for propylene glycol methyl ether (PGME), and an oral RfD was derived for its acetate (PGMEA). These values were based upon transient sedation observed in F344 rats and B6C3F1 mice during a two-year inhalation study. The dose-response relationship for sedation was characterized using internal dose measures as predicted by a physiologically based pharmacokinetic (PBPK) model for PGME and its acetate. PBPK modeling was used to account for changes in rodent physiology and metabolism due to aging and adaptation, based on data collected during weeksmore » 1, 2, 26, 52, and 78 of a chronic inhalation study. The peak concentration of PGME in richly perfused tissues was selected as the most appropriate internal dose measure based upon a consideration of the mode of action for sedation and similarities in tissue partitioning between brain and other richly perfused tissues. Internal doses (peak tissue concentrations of PGME) were designated as either no-observed-adverse-effect levels (NOAELs) or lowest-observed-adverse-effect levels (LOAELs) based upon the presence or absence of sedation at each time-point, species, and sex in the two year study. Distributions of the NOAEL and LOAEL values expressed in terms of internal dose were characterized using an arithmetic mean and standard deviation, with the mean internal NOAEL serving as the basis for the reference values, which was then divided by appropriate uncertainty factors. Where data were permitting, chemical-specific adjustment factors were derived to replace default uncertainty factor values of ten. Nonlinear kinetics are were predicted by the model in all species at PGME concentrations exceeding 100 ppm, which complicates interspecies and low-dose extrapolations. To address this complication, reference values were derived using two approaches which differ with respect to the order in which these extrapolations were performed: (1) uncertainty factor application followed by interspecies extrapolation (PBPK modeling); and (2) interspecies extrapolation followed by uncertainty factor application. The resulting reference values for these two approaches are substantially different, with values from the former approach being 7-fold higher than those from the latter approach. Such a striking difference between the two approaches reveals an underlying issue that has received little attention in the literature regarding the application of uncertainty factors and interspecies extrapolations to compounds where saturable kinetics occur in the range of the NOAEL. Until such discussions have taken place, reference values based on the latter approach are recommended for risk assessments involving human exposures to PGME and PGMEA.« less

Influence of Ultra-Low-Dose and Iterative Reconstructions on the Visualization of Orbital Soft Tissues on Maxillofacial CT.

PubMed

Widmann, G; Juranek, D; Waldenberger, F; Schullian, P; Dennhardt, A; Hoermann, R; Steurer, M; Gassner, E-M; Puelacher, W

2017-08-01

Dose reduction on CT scans for surgical planning and postoperative evaluation of midface and orbital fractures is an important concern. The purpose of this study was to evaluate the variability of various low-dose and iterative reconstruction techniques on the visualization of orbital soft tissues. Contrast-to-noise ratios of the optic nerve and inferior rectus muscle and subjective scores of a human cadaver were calculated from CT with a reference dose protocol (CT dose index volume = 36.69 mGy) and a subsequent series of low-dose protocols (LDPs I-4: CT dose index volume = 4.18, 2.64, 0.99, and 0.53 mGy) with filtered back-projection (FBP) and adaptive statistical iterative reconstruction (ASIR)-50, ASIR-100, and model-based iterative reconstruction. The Dunn Multiple Comparison Test was used to compare each combination of protocols (α = .05). Compared with the reference dose protocol with FBP, the following statistically significant differences in contrast-to-noise ratios were shown (all, P ≤ .012) for the following: 1) optic nerve: LDP-I with FBP; LDP-II with FBP and ASIR-50; LDP-III with FBP, ASIR-50, and ASIR-100; and LDP-IV with FBP, ASIR-50, and ASIR-100; and 2) inferior rectus muscle: LDP-II with FBP, LDP-III with FBP and ASIR-50, and LDP-IV with FBP, ASIR-50, and ASIR-100. Model-based iterative reconstruction showed the best contrast-to-noise ratio in all images and provided similar subjective scores for LDP-II. ASIR-50 had no remarkable effect, and ASIR-100, a small effect on subjective scores. Compared with a reference dose protocol with FBP, model-based iterative reconstruction may show similar diagnostic visibility of orbital soft tissues at a CT dose index volume of 2.64 mGy. Low-dose technology and iterative reconstruction technology may redefine current reference dose levels in maxillofacial CT. © 2017 by American Journal of Neuroradiology.

Assessment of dosimetric impact of system specific geometric distortion in an MRI only based radiotherapy workflow for prostate

NASA Astrophysics Data System (ADS)

Gustafsson, C.; Nordström, F.; Persson, E.; Brynolfsson, J.; Olsson, L. E.

2017-04-01

Dosimetric errors in a magnetic resonance imaging (MRI) only radiotherapy workflow may be caused by system specific geometric distortion from MRI. The aim of this study was to evaluate the impact on planned dose distribution and delineated structures for prostate patients, originating from this distortion. A method was developed, in which computer tomography (CT) images were distorted using the MRI distortion field. The displacement map for an optimized MRI treatment planning sequence was measured using a dedicated phantom in a 3 T MRI system. To simulate the distortion aspects of a synthetic CT (electron density derived from MR images), the displacement map was applied to CT images, referred to as distorted CT images. A volumetric modulated arc prostate treatment plan was applied to the original CT and the distorted CT, creating a reference and a distorted CT dose distribution. By applying the inverse of the displacement map to the distorted CT dose distribution, a dose distribution in the same geometry as the original CT images was created. For 10 prostate cancer patients, the dose difference between the reference dose distribution and inverse distorted CT dose distribution was analyzed in isodose level bins. The mean magnitude of the geometric distortion was 1.97 mm for the radial distance of 200-250 mm from isocenter. The mean percentage dose differences for all isodose level bins, were  ⩽0.02% and the radiotherapy structure mean volume deviations were  <0.2%. The method developed can quantify the dosimetric effects of MRI system specific distortion in a prostate MRI only radiotherapy workflow, separated from dosimetric effects originating from synthetic CT generation. No clinically relevant dose difference or structure deformation was found when 3D distortion correction and high acquisition bandwidth was used. The method could be used for any MRI sequence together with any anatomy of interest.

Assessment of dosimetric impact of system specific geometric distortion in an MRI only based radiotherapy workflow for prostate.

PubMed

Gustafsson, C; Nordström, F; Persson, E; Brynolfsson, J; Olsson, L E

2017-04-21

Dosimetric errors in a magnetic resonance imaging (MRI) only radiotherapy workflow may be caused by system specific geometric distortion from MRI. The aim of this study was to evaluate the impact on planned dose distribution and delineated structures for prostate patients, originating from this distortion. A method was developed, in which computer tomography (CT) images were distorted using the MRI distortion field. The displacement map for an optimized MRI treatment planning sequence was measured using a dedicated phantom in a 3 T MRI system. To simulate the distortion aspects of a synthetic CT (electron density derived from MR images), the displacement map was applied to CT images, referred to as distorted CT images. A volumetric modulated arc prostate treatment plan was applied to the original CT and the distorted CT, creating a reference and a distorted CT dose distribution. By applying the inverse of the displacement map to the distorted CT dose distribution, a dose distribution in the same geometry as the original CT images was created. For 10 prostate cancer patients, the dose difference between the reference dose distribution and inverse distorted CT dose distribution was analyzed in isodose level bins. The mean magnitude of the geometric distortion was 1.97 mm for the radial distance of 200-250 mm from isocenter. The mean percentage dose differences for all isodose level bins, were  ⩽0.02% and the radiotherapy structure mean volume deviations were  <0.2%. The method developed can quantify the dosimetric effects of MRI system specific distortion in a prostate MRI only radiotherapy workflow, separated from dosimetric effects originating from synthetic CT generation. No clinically relevant dose difference or structure deformation was found when 3D distortion correction and high acquisition bandwidth was used. The method could be used for any MRI sequence together with any anatomy of interest.

How accurately can the peak skin dose in fluoroscopy be determined using indirect dose metrics?

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

Jones, A. Kyle, E-mail: kyle.jones@mdanderson.org; Ensor, Joe E.; Pasciak, Alexander S.

Purpose: Skin dosimetry is important for fluoroscopically-guided interventions, as peak skin doses (PSD) that result in skin reactions can be reached during these procedures. There is no consensus as to whether or not indirect skin dosimetry is sufficiently accurate for fluoroscopically-guided interventions. However, measuring PSD with film is difficult and the decision to do so must be madea priori. The purpose of this study was to assess the accuracy of different types of indirect dose estimates and to determine if PSD can be calculated within ±50% using indirect dose metrics for embolization procedures. Methods: PSD were measured directly using radiochromicmore » film for 41 consecutive embolization procedures at two sites. Indirect dose metrics from the procedures were collected, including reference air kerma. Four different estimates of PSD were calculated from the indirect dose metrics and compared along with reference air kerma to the measured PSD for each case. The four indirect estimates included a standard calculation method, the use of detailed information from the radiation dose structured report, and two simplified calculation methods based on the standard method. Indirect dosimetry results were compared with direct measurements, including an analysis of uncertainty associated with film dosimetry. Factors affecting the accuracy of the different indirect estimates were examined. Results: When using the standard calculation method, calculated PSD were within ±35% for all 41 procedures studied. Calculated PSD were within ±50% for a simplified method using a single source-to-patient distance for all calculations. Reference air kerma was within ±50% for all but one procedure. Cases for which reference air kerma or calculated PSD exhibited large (±35%) differences from the measured PSD were analyzed, and two main causative factors were identified: unusually small or large source-to-patient distances and large contributions to reference air kerma from cone beam computed tomography or acquisition runs acquired at large primary gantry angles. When calculated uncertainty limits [−12.8%, 10%] were applied to directly measured PSD, most indirect PSD estimates remained within ±50% of the measured PSD. Conclusions: Using indirect dose metrics, PSD can be determined within ±35% for embolization procedures. Reference air kerma can be used without modification to set notification limits and substantial radiation dose levels, provided the displayed reference air kerma is accurate. These results can reasonably be extended to similar procedures, including vascular and interventional oncology. Considering these results, film dosimetry is likely an unnecessary effort for these types of procedures when indirect dose metrics are available.« less

Radiological Modeling for Determination of Derived Concentration Levels of an Area with Uranium Residual Material - 13533

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

Perez-Sanchez, Danyl

As a result of a pilot project developed at the old Spanish 'Junta de Energia Nuclear' to extract uranium from ores, tailings materials were generated. Most of these residual materials were sent back to different uranium mines, but a small amount of it was mixed with conventional building materials and deposited near the old plant until the surrounding ground was flattened. The affected land is included in an area under institutional control and used as recreational area. At the time of processing, uranium isotopes were separated but other radionuclides of the uranium decay series as Th-230, Ra-226 and daughters remainmore » in the residue. Recently, the analyses of samples taken at different ground's depths confirmed their presence. This paper presents the methodology used to calculate the derived concentration level to ensure that the reference dose level of 0.1 mSv y-1 used as radiological criteria. In this study, a radiological impact assessment was performed modeling the area as recreational scenario. The modelization study was carried out with the code RESRAD considering as exposure pathways, external irradiation, inadvertent ingestion of soil, inhalation of resuspended particles, and inhalation of radon (Rn-222). As result was concluded that, if the concentration of Ra-226 in the first 15 cm of soil is lower than, 0.34 Bq g{sup -1}, the dose would not exceed the reference dose. Applying this value as a derived concentration level and comparing with the results of measurements on the ground, some areas with a concentration of activity slightly higher than latter were found. In these zones the remediation proposal has been to cover with a layer of 15 cm of clean material. This action represents a reduction of 85% of the dose and ensures compliance with the reference dose. (authors)« less

Task-based image quality evaluation of iterative reconstruction methods for low dose CT using computer simulations

NASA Astrophysics Data System (ADS)

Xu, Jingyan; Fuld, Matthew K.; Fung, George S. K.; Tsui, Benjamin M. W.

2015-04-01

Iterative reconstruction (IR) methods for x-ray CT is a promising approach to improve image quality or reduce radiation dose to patients. The goal of this work was to use task based image quality measures and the channelized Hotelling observer (CHO) to evaluate both analytic and IR methods for clinical x-ray CT applications. We performed realistic computer simulations at five radiation dose levels, from a clinical reference low dose D0 to 25% D0. A fixed size and contrast lesion was inserted at different locations into the liver of the XCAT phantom to simulate a weak signal. The simulated data were reconstructed on a commercial CT scanner (SOMATOM Definition Flash; Siemens, Forchheim, Germany) using the vendor-provided analytic (WFBP) and IR (SAFIRE) methods. The reconstructed images were analyzed by CHOs with both rotationally symmetric (RS) and rotationally oriented (RO) channels, and with different numbers of lesion locations (5, 10, and 20) in a signal known exactly (SKE), background known exactly but variable (BKEV) detection task. The area under the receiver operating characteristic curve (AUC) was used as a summary measure to compare the IR and analytic methods; the AUC was also used as the equal performance criterion to derive the potential dose reduction factor of IR. In general, there was a good agreement in the relative AUC values of different reconstruction methods using CHOs with RS and RO channels, although the CHO with RO channels achieved higher AUCs than RS channels. The improvement of IR over analytic methods depends on the dose level. The reference dose level D0 was based on a clinical low dose protocol, lower than the standard dose due to the use of IR methods. At 75% D0, the performance improvement was statistically significant (p < 0.05). The potential dose reduction factor also depended on the detection task. For the SKE/BKEV task involving 10 lesion locations, a dose reduction of at least 25% from D0 was achieved.

Optimizing drug-dose alerts using commercial software throughout an integrated health care system.

PubMed

Saiyed, Salim M; Greco, Peter J; Fernandes, Glenn; Kaelber, David C

2017-11-01

All default electronic health record and drug reference database vendor drug-dose alerting recommendations (single dose, daily dose, dose frequency, and dose duration) were silently turned on in inpatient, outpatient, and emergency department areas for pediatric-only and nonpediatric-only populations. Drug-dose alerts were evaluated during a 3-month period. Drug-dose alerts fired on 12% of orders (104 098/834 911). System-level and drug-specific strategies to decrease drug-dose alerts were analyzed. System-level strategies included: (1) turning off all minimum drug-dosing alerts, (2) turning off all incomplete information drug-dosing alerts, (3) increasing the maximum single-dose drug-dose alert threshold to 125%, (4) increasing the daily dose maximum drug-dose alert threshold to 125%, and (5) increasing the dose frequency drug-dose alert threshold to more than 2 doses per day above initial threshold. Drug-specific strategies included changing drug-specific maximum single and maximum daily drug-dose alerting parameters for the top 22 drug categories by alert frequency. System-level approaches decreased alerting to 5% (46 988/834 911) and drug-specific approaches decreased alerts to 3% (25 455/834 911). Drug-dose alerts varied between care settings and patient populations. © The Author 2017. Published by Oxford University Press on behalf of the American Medical Informatics Association. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

TH-A-9A-01: Active Optical Flow Model: Predicting Voxel-Level Dose Prediction in Spine SBRT

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

Liu, J; Wu, Q.J.; Yin, F

2014-06-15

Purpose: To predict voxel-level dose distribution and enable effective evaluation of cord dose sparing in spine SBRT. Methods: We present an active optical flow model (AOFM) to statistically describe cord dose variations and train a predictive model to represent correlations between AOFM and PTV contours. Thirty clinically accepted spine SBRT plans are evenly divided into training and testing datasets. The development of predictive model consists of 1) collecting a sequence of dose maps including PTV and OAR (spinal cord) as well as a set of associated PTV contours adjacent to OAR from the training dataset, 2) classifying data into fivemore » groups based on PTV's locations relative to OAR, two “Top”s, “Left”, “Right”, and “Bottom”, 3) randomly selecting a dose map as the reference in each group and applying rigid registration and optical flow deformation to match all other maps to the reference, 4) building AOFM by importing optical flow vectors and dose values into the principal component analysis (PCA), 5) applying another PCA to features of PTV and OAR contours to generate an active shape model (ASM), and 6) computing a linear regression model of correlations between AOFM and ASM.When predicting dose distribution of a new case in the testing dataset, the PTV is first assigned to a group based on its contour characteristics. Contour features are then transformed into ASM's principal coordinates of the selected group. Finally, voxel-level dose distribution is determined by mapping from the ASM space to the AOFM space using the predictive model. Results: The DVHs predicted by the AOFM-based model and those in clinical plans are comparable in training and testing datasets. At 2% volume the dose difference between predicted and clinical plans is 4.2±4.4% and 3.3±3.5% in the training and testing datasets, respectively. Conclusion: The AOFM is effective in predicting voxel-level dose distribution for spine SBRT. Partially supported by NIH/NCI under grant #R21CA161389 and a master research grant by Varian Medical System.« less

Round-robin study of arsenic implant dose measurement in silicon by SIMS

NASA Astrophysics Data System (ADS)

Simons, D.; Kim, K.; Benbalagh, R.; Bennett, J.; Chew, A.; Gehre, D.; Hasegawa, T.; Hitzman, C.; Ko, J.; Lindstrom, R.; MacDonald, B.; Magee, C.; Montgomery, N.; Peres, P.; Ronsheim, P.; Yoshikawa, S.; Schuhmacher, M.; Stockwell, W.; Sykes, D.; Tomita, M.; Toujou, F.; Won, J.

2006-07-01

An international round-robin study was undertaken under the auspices of ISO TC201/SC6 to determine the best analytical conditions and the level of interlaboratory agreement for the determination of the implantation dose of arsenic in silicon by secondary ion mass spectrometry (SIMS). Fifteen SIMS laboratories, as well as two laboratories that performed low energy electron-induced X-ray emission spectrometry (LEXES) and one that made measurements by instrumental neutron activation analysis (INAA) were asked to determine the implanted arsenic doses in three unknown samples using as a comparator NIST Standard Reference Material ® 2134. The use of a common reference material by all laboratories resulted in better interlaboratory agreement than was seen in a previous round-robin that lacked a common comparator. The relative standard deviation among laboratories was less than 4% for the medium-dose sample, but several percent larger for the low- and high-dose samples. The high-dose sample showed a significant difference between point-by-point and average matrix normalization because the matrix signal decreased in the vicinity of the implant peak, as observed in a previous study. The dose from point-by-point normalization was in close agreement with that determined by INAA. No clear difference in measurement repeatability was seen when comparing Si 2- and Si 3- as matrix references with AsSi -.

Assessment of an organ‐based tube current modulation in thoracic computed tomography

PubMed Central

Sugai, Mai; Toyoda, Asami; Koshida, Haruka; Sakuta, Keita; Takata, Tadanori; Koshida, Kichiro; Iida, Hiroji; Matsui, Osamu

2012-01-01

Recently, specific computed tomography (CT) scanners have been equipped with organ‐based tube current modulation (TCM) technology. It is possible that organ‐based TCM will replace the conventional dose‐reduction technique of reducing the effective milliampere‐second. The aim of this study was to determine if organ‐based TCM could reduce radiation exposure to the breasts without compromising the image uniformity and beam hardening effect in thoracic CT examinations. Breast and skin radiation doses and the absorbed radiation dose distribution within a single section were measured with an anthropomorphic phantom and radiophotoluminescent glass dosimeters using four approaches to thoracic CT (reference, organ‐based TCM, copper shielding, and the combination of the above two techniques, hereafter referred to as the combination technique). The CT value and noise level were measured using the same calibration phantom. Organ‐based TCM and copper shielding reduced radiation doses to the breast by 23.7% and 21.8%, respectively. However, the CT value increased, especially in the anterior region, using copper shielding. In contrast, the CT value and noise level barely increased using organ‐based TCM. The combination technique reduced the radiation dose to the breast by 38.2%, but greatly increased the absorbed radiation dose from the central to the posterior regions. Moreover, the CT value increased in the anterior region and the noise level increased by more than 10% in the entire region. Therefore, organ‐based TCM can reduce radiation doses to breasts with only small increases in noise levels, making it preferable for specific groups of patients, such as children and young women. PACS numbers: 87.53.Bn; 87.57.Q‐; 87.57.qp PMID:22402390

Economic implications of mercury exposure in the context of the global mercury treaty: Hair mercury levels and estimated lost economic productivity in selected developing countries.

PubMed

Trasande, Leonardo; DiGangi, Joseph; Evers, David C; Petrlik, Jindrich; Buck, David G; Šamánek, Jan; Beeler, Bjorn; Turnquist, Madeline A; Regan, Kevin

2016-12-01

Several developing countries have limited or no information about exposures near anthropogenic mercury sources and no studies have quantified costs of mercury pollution or economic benefits to mercury pollution prevention in these countries. In this study, we present data on mercury concentrations in human hair from subpopulations in developing countries most likely to benefit from the implementation of the Minamata Convention on Mercury. These data are then used to estimate economic costs of mercury exposure in these communities. Hair samples were collected from sites located in 15 countries. We used a linear dose-response relationship that previously identified a 0.18 IQ point decrement per part per million (ppm) increase in hair mercury, and modeled a base case scenario assuming a reference level of 1 ppm, and a second scenario assuming no reference level. We then estimated the corresponding increases in intellectual disability and lost Disability-Adjusted Life Years (DALY). A total of 236 participants provided hair samples for analysis, with an estimated population at risk of mercury exposure near the 15 sites of 11,302,582. Average mercury levels were in the range of 0.48 ppm-4.60 ppm, and 61% of all participants had hair mercury concentrations greater than 1 ppm, the level that approximately corresponds to the USA EPA reference dose. An additional 1310 cases of intellectual disability attributable to mercury exposure were identified annually (4110 assuming no reference level), resulting in 16,501 lost DALYs (51,809 assuming no reference level). A total of $77.4 million in lost economic productivity was estimated assuming a 1 ppm reference level and $130 million if no reference level was used. We conclude that significant mercury exposures occur in developing and transition country communities near sources named in the Minamata Convention, and our estimates suggest that a large economic burden could be avoided by timely implementation of measures to prevent mercury exposures. Copyright © 2016 Elsevier Ltd. All rights reserved.

Dose measurements in intraoral radiography using thermoluminescent dosimeters

NASA Astrophysics Data System (ADS)

Azorín, C.; Azorín, J.; Aguirre, F.; Rivera, T.

2015-01-01

The use of X-ray in medicine demands to expose the patient and the professional to the lowest radiation doses available in agreement with ALARA philosophy. The reference level for intraoral dental radiography is 7 mGy and, in Mexico, a number of examinations of this type are performed annually. It is considered that approximately 25% of all the X-rays examinations carried out in our country correspond to intraoral radiographies. In other hand, most of the intraoral X-ray equipment correspond to conventional radiological systems using film, which are developed as much manual as automatically. In this work the results of determining the doses received by the patients in intraoral radiological examinations made with different radiological systems using LiF:Mg,Cu,P+PTFE thermoluminescent dosimeters are presented. In some conventional radiological systems using film, when films are developed manual or automatically, incident kerma up to 10.61 ± 0.74 mGv were determined. These values exceed that reference level suggested by the IAEA and in the Mexican standards for intraoral examinations.

Multidetector CT radiation dose optimisation in adults: short- and long-term effects of a clinical audit.

PubMed

Tack, Denis; Jahnen, Andreas; Kohler, Sarah; Harpes, Nico; De Maertelaer, Viviane; Back, Carlo; Gevenois, Pierre Alain

2014-01-01

To report short- and long-term effects of an audit process intended to optimise the radiation dose from multidetector row computed tomography (MDCT). A survey of radiation dose from all eight MDCT departments in the state of Luxembourg performed in 2007 served as baseline, and involved the most frequently imaged regions (head, sinus, cervical spine, thorax, abdomen, and lumbar spine). CT dose index volume (CTDIvol), dose-length product per acquisition (DLP/acq), and DLP per examination (DLP/exa) were recorded, and their mean, median, 25th and 75th percentiles compared. In 2008, an audit conducted in each department helped to optimise doses. In 2009 and 2010, two further surveys evaluated the audit's impact on the dose delivered. Between 2007 and 2009, DLP/exa significantly decreased by 32-69 % for all regions (P < 0.001) except the lumbar spine (5 %, P = 0.455). Between 2009 and 2010, DLP/exa significantly decreased by 13-18 % for sinus, cervical and lumbar spine (P ranging from 0.016 to less than 0.001). Between 2007 and 2010, DLP/exa significantly decreased for all regions (18-75 %, P < 0.001). Collective dose decreased by 30 % and the 75th percentile (diagnostic reference level, DRL) by 20-78 %. The audit process resulted in long-lasting dose reduction, with DRLs reduced by 20-78 %, mean DLP/examination by 18-75 %, and collective dose by 30 %. • External support through clinical audit may optimise default parameters of routine CT. • Reduction of 75th percentiles used as reference diagnostic levels is 18-75 %. • The effect of this audit is sustainable over time. • Dose savings through optimisation can be added to those achievable through CT.

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

Dourson, M.L.

The quantitative procedures associated with noncancer risk assessment include reference dose (RfD), benchmark dose, and severity modeling. The RfD, which is part of the EPA risk assessment guidelines, is an estimation of a level that is likely to be without any health risk to sensitive individuals. The RfD requires two major judgments: the first is choice of a critical effect(s) and its No Observed Adverse Effect Level (NOAEL); the second judgment is choice of an uncertainty factor. This paper discusses major assumptions and limitations of the RfD model.

[Estimation of Maximum Entrance Skin Dose during Cerebral Angiography].

PubMed

Kawauchi, Satoru; Moritake, Takashi; Hayakawa, Mikito; Hamada, Yusuke; Sakuma, Hideyuki; Yoda, Shogo; Satoh, Masayuki; Sun, Lue; Koguchi, Yasuhiro; Akahane, Keiichi; Chida, Koichi; Matsumaru, Yuji

2015-09-01

Using radio-photoluminescence glass dosimeter, we measured the entrance skin dose (ESD) in 46 cases and analyzed the correlations between maximum ESD and angiographic parameters [total fluoroscopic time (TFT); number of digital subtraction angiography (DSA) frames, air kerma at the interventional reference point (AK), and dose-area product (DAP)] to estimate the maximum ESD in real time. Mean (± standard deviation) maximum ESD, dose of the right lens, and dose of the left lens were 431.2 ± 135.8 mGy, 33.6 ± 15.5 mGy, and 58.5 ± 35.0 mGy, respectively. Correlation coefficients (r) between maximum ESD and TFT, number of DSA frames, AK, and DAP were r=0.379 (P<0.01), r=0.702 (P<0.001), r=0.825 (P<0.001), and r=0.709 (P<0.001), respectively. AK was identified as the most useful parameter for real-time prediction of maximum ESD. This study should contribute to the development of new diagnostic reference levels in our country.

A systematic review of Bisphenol A "low dose" studies in the context of human exposure: a case for establishing standards for reporting "low-dose" effects of chemicals.

PubMed

Teeguarden, Justin G; Hanson-Drury, Sesha

2013-12-01

Human exposure to the chemical Bisphenol A is almost ubiquitous in surveyed industrialized societies. Structural features similar to estrogen confer the ability of Bisphenol A (BPA) to bind estrogen receptors, giving BPA membership in the group of environmental pollutants called endocrine disruptors. References by scientists, the media, political entities, and non-governmental organizations to many toxicity studies as "low dose" has led to the belief that exposure levels in these studies are similar to humans, implying that BPA is toxic to humans at current exposures. Through systematic, objective comparison of our current, and a previous compilation of the "low-dose" literature to multiple estimates of human external and internal exposure levels, we found that the "low-dose" moniker describes exposures covering 8-12 orders of magnitude, the majority (91-99% of exposures) being greater than the upper bound of human exposure in the general infant, child and adult U.S. Population. "low dose" is therefore a descriptor without specific meaning regarding human exposure. Where human exposure data are available, for BPA and other environmental chemicals, reference to toxicity study exposures by direct comparison to human exposure would be more informative, more objective, and less susceptible to misunderstanding. Copyright © 2013 Elsevier Ltd. All rights reserved.

Dose audit for patients undergoing two common radiography examinations with digital radiology systems.

PubMed

İnal, Tolga; Ataç, Gökçe

2014-01-01

We aimed to determine the radiation doses delivered to patients undergoing general examinations using computed or digital radiography systems in Turkey. Radiographs of 20 patients undergoing posteroanterior chest X-ray and of 20 patients undergoing anteroposterior kidney-ureter-bladder radiography were evaluated in five X-ray rooms at four local hospitals in the Ankara region. Currently, almost all radiology departments in Turkey have switched from conventional radiography systems to computed radiography or digital radiography systems. Patient dose was measured for both systems. The results were compared with published diagnostic reference levels (DRLs) from the European Union and International Atomic Energy Agency. The average entrance surface doses (ESDs) for chest examinations exceeded established international DRLs at two of the X-ray rooms in a hospital with computed radiography. All of the other ESD measurements were approximately equal to or below the DRLs for both examinations in all of the remaining hospitals. Improper adjustment of the exposure parameters, uncalibrated automatic exposure control systems, and failure of the technologists to choose exposure parameters properly were problems we noticed during the study. This study is an initial attempt at establishing local DRL values for digital radiography systems, and will provide a benchmark so that the authorities can establish reference dose levels for diagnostic radiology in Turkey.

Effective DQE (eDQE) and dose to optimize radiographic technical parameters: a survey of pediatric chest X-ray examinations in Korea.

PubMed

Park, Hye-Suk; Kim, Ye-Seul; Park, Ok-Seob; Kim, Sang-Tae; Jeon, Chang-Woo; Kim, Hee-Joung

2014-04-01

The purpose of this study was to investigate the effect of various technical parameters for dose optimization in pediatric chest radiological examinations by evaluating effective dose and effective detective quantum efficiency (eDQE). For tube voltages ranging from 40 to 90 kV in 10 kV increments at the focus-to-detector distance (FDD) of 100, 110, 120, 150, 180 cm, the eDQE was evaluated at same effective dose. The eDQE was considerably higher without the use of the grid on equivalent effective dose. This indicates that the reduction of scatter radiation did not compensate for the loss of absorbed effective photons in the grid. The eDQE increased with increasing FDD because of the greater effective modulation transfer function (eMTF) with lower focal spot blurring. However, most of the major hospitals in Korea employed a short FDD of 100 cm with the grid. The entrance surface air kerma values for the hospitals of this survey exceeded the Korean reference level of 100 μGy. The different reference levels might be appropriate for the same examination conducted on children of different ages. Also, it is necessary to refine the technical parameters to perform pediatric chest examinations.

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

Cheung, Michael L M; Chan, Anthony T C; The Chinese University of Hong Kong

Purpose: To develop a formulation for 4D treatment planning for a tumour tracking volumetric modulated arc therapy treatment (VMAT) plan for lung cancer. Methods: A VMAT plan was optimized based on a reference phase of the 4DCT of a lung cancer patient. The PTV was generated from the GTV of the reference phase. The collimator angle was set to 90 degrees such that the MLC travels along superior-inferior direction which is the main component of movement of a lung tumour. Then, each control point of the VMAT plan was assigned to a particular phase of the 4DCT in chronological order.more » The MLC positions of each control point were shifted according to the position of the tumour centroid of its assigned phase to form a tumour tracking VMAT plan. The control points of the same phase were grouped to form a pseudo VMAT plan for that particular phase. Dose calculation was performed for each pseudo VMAT plan on the corresponding phase of the 4DCT. The CTs of all phases were registered to the reference phase CT according to the displacement of the tumour centroid. The individual dose distributions of the pseudo VMAT plans were summed up and displayed on the reference phase of the 4DCT. A control VMAT plan was optimized based on a PTV generated from the ITV of all phases and compared with the tumour tracking VMAT plan. Results: Both plans achieved >95% volume coverage at the prescription dose level (96% for the tumour tracking plan and 97% for the control plan). But the normal lung volume irradiated at the prescription dose level was 39% less for the tumour tracking plan than the control plan. Conclusion: A formulation of 4D treatment planning for tumour tracking VMAT plans for lung cancer was developed.« less

TLD and OSLD dosimetry systems for remote audits of radiotherapy external beam calibration.

PubMed

Alvarez, P; Kry, S F; Stingo, F; Followill, D

2017-11-01

The Imaging and Radiation Oncology Core QA Center in Houston (IROC-H) performs remote dosimetry audits of more than 20,000 megavoltage photon and electron beams each year. Both a thermoluminescent dosimeter (TLD-100) and optically stimulated luminescent dosimeter (OSLD; nanoDot) system are commissioned for this task, with the OSLD system being predominant due to the more time-efficient read-out process. The measurement apparatus includes 3 TLD or 2 OSLD in an acrylic mini-phantom, which are irradiated by the institution under reference geometry. Dosimetry systems are calibrated based on the signal-to-dose conversion established with reference dosimeters irradiated in a Co-60 beam, using a reference dose of 300 cGy for TLD and 100 cGy for OSLD. The uncertainty in the dose determination is 1.3% for TLD and 1.6% for OSLD at the one sigma level. This accuracy allows for a tolerance of ±5% to be used.

SU-E-P-57: Radiation Doses Assessment to Paediatric Patients for Some Digital Diagnostic Radiology Examination in Emergency Department in Qatar

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

Abdallah, I; Aly, A; Al Naemi, H

Purpose: The aim of this study was to evaluate radiation doses to pediatric patients undergoing standard radiographic examinations using Direct Digital Radiography (DDR) in Paediatric emergency center of Hamad General Hospital (HGH) in state of Qatar and compared with regional and international Dose Reference Levels (DRLs). Methods: Entrance Skin Dose (ESD) was measured for 2739 patients for two common X-ray examinations namely: Chest AP/PA, Abdomen. Exposure factors such as kV, mAs and Focal to Skin Distance (FSD) were recorded for each patient. Tube Output was measured for a range of selected kV values. ESD for each individual patient was calculatedmore » using the tube output and the technical exposure factors for each examination. The ESD values were compared with the some international Dose Reference Levels (DRL) for all types of examinations. Results: The most performed procedure during the time of this study was chest PA/PA (85%). The mean ESD values obtained from AP chest, PA chest and AP abdomen ranged 91–120, 80–84 and 209 – 659 µGy per radiograph for different age’s groups respectively. Two protocols have been used for chest AP and PA using different radiological parameters, and the different of ESD values for chest PA and were 41% for 1 years old child, 57% for 5 years old for chest AP. Conclusion: The mean ESD were compared with those found in literature and were found to be comparable. The radiation dose can be reduced more for Chest AP and PA examination by optimization of each investigation and hence more studies are required for this task. The results presented will serve as a baseline data needed for deriving local reference doses for pediatric X-ray examinations in this local department and hence it can be applied in the whole Qatar.« less

National reference doses for dental cephalometric radiography.

PubMed

Holroyd, J R

2011-12-01

Diagnostic reference levels (DRLs) are an important tool in the optimisation of clinical radiography. Although national DRLs are provided for many diagnostic procedures including dental intra-oral radiography, there are currently no national DRLs set for cephalometric radiography. In the absence of formal national DRLs, the Health Protection Agency (HPA) has previously published National Reference Doses (NRDs) covering a wide range of diagnostic X-ray examinations. The aim of this study was to determine provisional NRDs for cephalometric radiography. Measurements made by the Dental X-ray Protection Service (DXPS) of the HPA, as part of the cephalometric X-ray equipment testing service provided to dentists and dental trade companies throughout the UK, were used to derive provisional NRDs. Dose-area product measurements were made on 42 X-ray sets. Third quartile dose-area product values for adult and child lateral cephalometric radiography were found to be 41 mGy cm² and 25 mGy cm², respectively, with individual measurements ranging from 3 mGy cm² to 108 mGy cm². This report proposes provisional NRDs of 40 mGy cm² and 25 mGy cm² for adult and child lateral cephalometric radiographs, respectively; these doses could be considered by employers when establishing their local DRLs.

Effects of Altering Levothyroxine (L-T4) Doses on Quality of Life, Mood, and Cognition in L-T4 Treated Subjects.

PubMed

Samuels, Mary H; Kolobova, Irina; Niederhausen, Meike; Janowsky, Jeri S; Schuff, Kathryn G

2018-05-01

The brain is a critical target organ for thyroid hormone, but it is unclear whether variations in thyroid function within and near the reference range affect quality of life, mood, or cognition. A total of 138 subjects with levothyroxine (L-T4)-treated hypothyroidism and normal thyrotropin (TSH) levels underwent measures of quality of life (36-Item Short Form Health Survey, Underactive Thyroid-Dependent Quality of Life Questionnaire), mood (Profile of Mood States, Affective Lability Scale), and cognition (executive function, memory). They were then randomly assigned to receive an unchanged, higher, or lower L-T4 dose in double-blind fashion, targeting one of three TSH ranges (0.34 to 2.50, 2.51 to 5.60, or 5.61 to 12.0 mU/L). Doses were adjusted every 6 weeks based on TSH levels. Baseline measures were reassessed at 6 months. At the end of the study, by intention to treat, mean L-T4 doses were 1.50 ± 0.07, 1.32 ± 0.07, and 0.78 ± 0.08 μg/kg (P < 0.001), and mean TSH levels were 1.85 ± 0.25, 3.93 ± 0.38, and 9.49 ± 0.80 mU/L (P < 0.001), respectively, in the three arms. There were minor differences in a few outcomes between the three arms, which were no longer significant after correction for multiple comparisons. Subjects could not ascertain how their L-T4 doses had been adjusted (P = 0.55) but preferred L-T4 doses they perceived to be higher (P < 0.001). Altering L-T4 doses in hypothyroid subjects to vary TSH levels in and near the reference range does not affect quality of life, mood, or cognition. L-T4-treated subjects prefer perceived higher L-T4 doses despite a lack of objective benefit. Adjusting L-T4 doses in hypothyroid patients based on symptoms in these areas may not result in significant clinical improvement.

Dosimetric evaluation of high-dose-rate interstitial brachytherapy boost treatments for localized prostate cancer.

PubMed

Fröhlich, Georgina; Agoston, Péter; Lövey, József; Somogyi, András; Fodor, János; Polgár, Csaba; Major, Tibor

2010-07-01

To quantitatively evaluate the dose distributions of high-dose-rate (HDR) prostate implants regarding target coverage, dose homogeneity, and dose to organs at risk. Treatment plans of 174 implants were evaluated using cumulative dose-volume histograms (DVHs). The planning was based on transrectal ultrasound (US) imaging, and the prescribed dose (100%) was 10 Gy. The tolerance doses to rectum and urethra were 80% and 120%, respectively. Dose-volume parameters for target (V90, V100, V150, V200, D90, D(min)) and quality indices (DNR [dose nonuniformity ratio], DHI [dose homogeneity index], CI [coverage index], COIN [conformal index]) were calculated. Maximum dose in reference points of rectum (D(r)) and urethra (D(u)), dose to volume of 2 cm(3) of the rectum (D(2ccm)), and 0.1 cm(3) and 1% of the urethra (D(0.1ccm) and D1) were determined. Nonparametric correlation analysis was performed between these parameters. The median number of needles was 16, the mean prostate volume (V(p)) was 27.1 cm(3). The mean V90, V100, V150, and V200 were 99%, 97%, 39%, and 13%, respectively. The mean D90 was 109%, and the D(min) was 87%. The mean doses in rectum and urethra reference points were 75% and 119%, respectively. The mean volumetric doses were D(2ccm) = 49% for the rectum, D(0.1ccm) = 126%, and D1 = 140% for the urethra. The mean DNR was 0.37, while the DHI was 0.60. The mean COIN was 0.66. The Spearman rank order correlation coefficients for volume doses to rectum and urethra were R(D(r),D(2ccm)) = 0.69, R(D(u),D0.(1ccm)) = 0.64, R(D(u),D1) = 0.23. US-based treatment plans for HDR prostate implants based on the real positions of catheters provided acceptable dose distributions. In the majority of the cases, the doses to urethra and rectum were kept below the defined tolerance levels. For rectum, the dose in reference points correlated well with dose-volume parameters. For urethra dose characterization, the use of D1 volumetric parameter is recommended.

Eye lens dosimetry in interventional cardiology: results of staff dose measurements and link to patient dose levels.

PubMed

Antic, V; Ciraj-Bjelac, O; Rehani, M; Aleksandric, S; Arandjic, D; Ostojic, M

2013-01-01

Workers involved in interventional cardiology procedures receive high eye lens dose if protection is not used. Currently, there is no suitable method for routine use for the measurement of eye dose. Since most angiography machines are equipped with suitable patient dosemeters, deriving factors linking staff eye doses to the patient doses can be helpful. In this study the patient kerma-area product, cumulative dose at an interventional reference point and eye dose in terms of Hp(3) of the cardiologists, nurses and radiographers for interventional cardiology procedures have been measured. Correlations between the patient dose and the staff eye dose were obtained. The mean eye dose was 121 µSv for the first operator, 33 µSv for the second operator/nurse and 12 µSv for radiographer. Normalised eye lens doses per unit kerma-area product were 0.94 µSv Gy⁻¹ cm⁻² for the first operator, 0.33 µSv Gy⁻¹ cm⁻² for the second operator/nurse and 0.16 µSv Gy⁻¹ cm⁻² for radiographers. Statistical analysis indicated that there is a weak but significant (p < 0.01) correlation between the eye dose and the kerma-area product for all three staff categories. These values are based on a local practice and may provide useful reference for other studies for validation and for wider utilisation in assessing the eye dose using patient dose values.

Ambient Dose Equivalent in S. Paulo and Bauru cities

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

Umisedo, Nancy K.; Okuno, Emico; Cancio, Francisco S.

2008-08-07

The Laboratory of Dosimetry (Institute of Physics, University of S. Paulo) performs since 1981 the external individual monitoring of workers exposed to X and gamma rays based on thermoluminescent dosimetry (TLD). Personal dose equivalent refers only to the exposure of workers due to the working activities, and the dose due to background radiation, also measured with TLD, must be subtracted to evaluate it. A compilation of ambient dose equivalent was done to evaluate the dose due to the background radiation in the work places, and also to contribute to the knowledge of the level of indoor radiation to which themore » public is exposed.« less

Effect of N-acetylcysteine administration on homocysteine level, oxidative damage to proteins, and levels of iron (Fe) and Fe-related proteins in lead-exposed workers.

PubMed

Kasperczyk, Sławomir; Dobrakowski, Michał; Kasperczyk, Aleksandra; Romuk, Ewa; Rykaczewska-Czerwińska, Monika; Pawlas, Natalia; Birkner, Ewa

2016-09-01

N-Acetylcysteine (NAC) could be included in protocols designed for the treatment of lead toxicity. Therefore, in this study, we decided to investigate the influence of NAC administration on homocysteine (Hcy) levels, oxidative damage to proteins, and the levels of iron (Fe), transferrin (TRF), and haptoglobin (HPG) in lead (Pb)-exposed workers. The examined population (n = 171) was composed of male employees who worked with Pb. They were randomized into four groups. Workers who were not administered any antioxidants, drugs, vitamins, or dietary supplements were classified as the reference group (n = 49). The remaining three groups consisted of workers who were treated orally with NAC at three different doses (1 × 200, 2 × 200, or 2 × 400 mg) for 12 weeks. After the treatment, blood Pb levels significantly decreased in the groups receiving NAC compared with the reference group. The protein concentration was not affected by NAC administration. In contrast, Hcy levels significantly decreased or showed a strong tendency toward lower values depending on the NAC dose. Levels of the protein carbonyl groups were significantly decreased in all of the groups receiving NAC. Conversely, glutamate dehydrogenase activity was significantly elevated in all of the groups receiving NAC, while the level of protein thiol groups was significantly elevated only in the group receiving 200 mg of NAC. Treatment with NAC did not significantly affect Fe and TRF levels, whereas HPG levels showed a tendency toward lower values. Treatment with NAC normalized the level of Hcy and decreased oxidative stress as measured by the protein carbonyl content; this effect occurred in a dose-dependent manner. Moreover, small doses of NAC elevated the levels of protein thiol groups. Therefore, NAC could be introduced as an alternative therapy for chronic Pb toxicity in humans. © The Author(s) 2015.

Pharmacokinetic equivalence of a levothyroxine sodium soft capsule manufactured using the new food and drug administration potency guidelines in healthy volunteers under fasting conditions.

PubMed

Colucci, Philippe; D'Angelo, Pina; Mautone, Giuseppe; Scarsi, Claudia; Ducharme, Murray P

2011-06-01

To assess the pharmacokinetic equivalence of a new soft capsule formulation of levothyroxine versus a marketed reference product and to assess the soft capsule formulated with stricter potency guidelines versus the capsule before the implementation of the new potency rule. Two single-dose randomized two-way crossover pharmacokinetic equivalence studies and one dosage form proportionality single-dose study comparing low, medium, and high strengths of the new formulation. All three studies were performed in a clinical setting. Participants were healthy male and female adult subjects with normal levothyroxine levels. A total of 90 subjects participated in the three studies. Pharmacokinetic parameters were calculated on baseline- adjusted concentrations. The first pharmacokinetic equivalence study compared the levothyroxine sodium soft capsule formulation (Tirosint) with the reference Synthroid tablets and the two products were considered bioequivalent. The dosage form proportionality study compared the 50-, 100-, and 150-μg test capsules strengths dosed at the same level (600 μg) and all three strengths were considered equivalent when given at the same dosage. The last study compared the test capsule used in the first two studies with a new capsule formulation following the new potency guideline (±5%) set forward by the Food and Drug Administration and the two capsules were considered bioequivalent. Doses were well tolerated by subjects in all three studies with no serious adverse events reported. The levothyroxine soft capsule formulated with the stricter new potency guideline set forward by the Food and Drug Administration met equivalence criteria in terms of rate and extent of exposure under fasting conditions to the reference tablet formulation. Clinical doses of the capsule formulation can be given using any combination of the commercialized strengths.

Effect of hydrogen fluoride on pollen germination and pollen tube growth in Prunus avium L. cv. Royal Ann

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

Facteau, T.J.; Wang, S.Y.; Rowe, K.E.

1973-05-01

Increased fluoride (F) fumigation levels resulted in decrease in percent Royal Ann pollen germination and pollen tube growth. As dose (hour x concentration in ..mu.. gF/m/sup 3/) increased, Van pollen tube growth in vivo decreased. A linear relationship between increased dose and fluoride residue in the flowers was shown. 14 references, 5 figures.

Comparison of two dose regimens of growth hormone (GH) with different target IGF-1 levels on glucose metabolism, lipid profile, cardiovascular function and anthropometric parameters in gh-deficient adults.

PubMed

Cenci, Maria Claudia Peixoto; Soares, Débora Vieira; Spina, Luciana Diniz Carneiro; Brasil, Rosane Resende de Lima Oliveira; Lobo, Priscila Marise; Michmacher, Eduardo; Vaisman, Mario; Boguszewski, Cesar Luiz; Conceição, Flávia Lúcia

2012-01-01

To compare the effects of two regimens of GH therapy with different target IGF-1 levels on anthropometric parameters, glucose metabolism, lipid profile and cardiac function in adults with GH deficiency (GHD). Retrospective analysis of 14 GHD adults from Clementino Fraga Filho University Hospital, Rio de Janeiro, Brazil, who were treated with a GH regimen aimed at maintaining serum IGF-1 levels between the median and upper reference limit (high dose group - HDGH) and 18 GHD adults from Federal University Hospital, Curitiba, Brazil, who received a fixed GH dose of 0.2mg/day in the first year of treatment, followed by titration to maintain serum IGF-1 levels between the median and lower reference limit (low dose group - LDGH). All patients were followed for 2 years with analysis of anthropometric parameters, serum levels of IGF-1, glucose, insulin, HOMA-IR, lipid profile, and transthoracic echocardiography. Changes on weight, BMI and waist circumference were similar between the two groups. Insulin levels increased and HOMA-IR worsened in the LDGH group at 1year and improved thereafter. Total cholesterol and triglycerides did not change with therapy. LDL cholesterol reduced in both groups, while HDL-cholesterol significantly increased only in the HDGH group (p=0.007 vs LDGH). No significant variations on echocardiographic parameters were observed. The HDGH and LDGH regimens resulted in similar changes on anthropometric, echocardiographic, glucose and lipid parameters in GHD adults, except for increase in HDL cholesterol that was only observed in the HDGH regimen. Copyright © 2012 Elsevier Ltd. All rights reserved.

SUDOQU, a new dose-assessment methodology for radiological surface contamination.

PubMed

van Dillen, Teun; van Dijk, Arjan

2018-06-12

A new methodology has been developed for the assessment of the annual effective dose resulting from removable and fixed radiological surface contamination. It is entitled SUDOQU (SUrface DOse QUantification) and it can for instance be used to derive criteria for surface contamination related to the import of non-food consumer goods, containers and conveyances, e.g., limiting values and operational screening levels. SUDOQU imposes mass (activity)-balance equations based on radioactive decay, removal and deposition processes in indoor and outdoor environments. This leads to time-dependent contamination levels that may be of particular importance in exposure scenarios dealing with one or a few contaminated items only (usually public exposure scenarios, therefore referred to as the 'consumer' model). Exposure scenarios with a continuous flow of freshly contaminated goods also fall within the scope of the methodology (typically occupational exposure scenarios, thus referred to as the 'worker model'). In this paper we describe SUDOQU, its applications, and its current limitations. First, we delineate the contamination issue, present the assumptions and explain the concepts. We describe the relevant removal, transfer, and deposition processes, and derive equations for the time evolution of the radiological surface-, air- and skin-contamination levels. These are then input for the subsequent evaluation of the annual effective dose with possible contributions from external gamma radiation, inhalation, secondary ingestion (indirect, from hand to mouth), skin contamination, direct ingestion and skin-contact exposure. The limiting effective surface dose is introduced for issues involving the conservatism of dose calculations. SUDOQU can be used by radiation-protection scientists/experts and policy makers in the field of e.g. emergency preparedness, trade and transport, exemption and clearance, waste management, and nuclear facilities. Several practical examples are worked out demonstrating the potential applications of the methodology. . Creative Commons Attribution license.

Benchmarking pediatric cranial CT protocols using a dose tracking software system: a multicenter study.

PubMed

De Bondt, Timo; Mulkens, Tom; Zanca, Federica; Pyfferoen, Lotte; Casselman, Jan W; Parizel, Paul M

2017-02-01

To benchmark regional standard practice for paediatric cranial CT-procedures in terms of radiation dose and acquisition parameters. Paediatric cranial CT-data were retrospectively collected during a 1-year period, in 3 different hospitals of the same country. A dose tracking system was used to automatically gather information. Dose (CTDI and DLP), scan length, amount of retakes and demographic data were stratified by age and clinical indication; appropriate use of child-specific protocols was assessed. In total, 296 paediatric cranial CT-procedures were collected. Although the median dose of each hospital was below national and international diagnostic reference level (DRL) for all age categories, statistically significant (p-value < 0.001) dose differences among hospitals were observed. The hospital with lowest dose levels showed smallest dose variability and used age-stratified protocols for standardizing paediatric head exams. Erroneous selection of adult protocols for children still occurred, mostly in the oldest age-group. Even though all hospitals complied with national and international DRLs, dose tracking and benchmarking showed that further dose optimization and standardization is possible by using age-stratified protocols for paediatric cranial CT. Moreover, having a dose tracking system revealed that adult protocols are still applied for paediatric CT, a practice that must be avoided. • Significant differences were observed in the delivered dose between age-groups and hospitals. • Using age-adapted scanning protocols gives a nearly linear dose increase. • Sharing dose-data can be a trigger for hospitals to reduce dose levels.

Prolactin is a peripheral marker of manganese neurotoxicity

PubMed Central

Marreilha dos Santos, AP; Lopes Santos, M; BatorÉu, Maria C; Aschner, M

2011-01-01

Excessive exposure to Mn induces neurotoxicity, referred to as manganism. Exposure assessment relies on Mn blood and urine analyses, both of which show poor correlation to exposure. Accordingly, there is a critical need for better surrogate biomarkers of Mn exposure. The aim of this study was to examine the relationship between Mn exposure and early indicators of neurotoxicity, with particular emphasis on peripheral biomarkers. Male Wistar rats (180–200 g) were injected intraperitoneally with 4 or 8 doses of Mn (10 mg/kg). Mn exposure was evaluated by analysis of Mn levels in brain and blood along with biochemical end-points (see below). Results Brain Mn levels were significantly increased both after 4 and 8 doses of Mn compared with controls (p<0.001). Blood levels failed to reflect a dose-dependent increase in brain Mn, with only the 8-dose treated group showing significant differences (p<0.001). Brain glutathione (GSH) levels were significantly decreased in the 8-dose-treated animals (p<0.001). A significant and dose-dependent increase in prolactin levels was found for both treated groups (p<0.001) compared to controls. In addition, a decrease in motor activity was observed in the 8-dose-treated group compared to controls. Conclusions 1) The present study demonstrates that peripheral blood level is a poor indicator of Mn brain accumulation and exposure; 2) Mn reduces GSH brain levels, likely reflecting oxidative stress; 3) Mn increases blood prolactin levels, indicating changes in the integrity of the dopaminergic system. Taken together these results suggest that peripheral prolactin levels may serve as reliable predictive biomarkers of Mn neurotoxicity. PMID:21262206

Dose audit for patients undergoing two common radiography examinations with digital radiology systems

PubMed Central

İnal, Tolga; Ataç, Gökçe

2014-01-01

PURPOSE We aimed to determine the radiation doses delivered to patients undergoing general examinations using computed or digital radiography systems in Turkey. MATERIALS AND METHODS Radiographs of 20 patients undergoing posteroanterior chest X-ray and of 20 patients undergoing anteroposterior kidney-ureter-bladder radiography were evaluated in five X-ray rooms at four local hospitals in the Ankara region. Currently, almost all radiology departments in Turkey have switched from conventional radiography systems to computed radiography or digital radiography systems. Patient dose was measured for both systems. The results were compared with published diagnostic reference levels (DRLs) from the European Union and International Atomic Energy Agency. RESULTS The average entrance surface doses (ESDs) for chest examinations exceeded established international DRLs at two of the X-ray rooms in a hospital with computed radiography. All of the other ESD measurements were approximately equal to or below the DRLs for both examinations in all of the remaining hospitals. Improper adjustment of the exposure parameters, uncalibrated automatic exposure control systems, and failure of the technologists to choose exposure parameters properly were problems we noticed during the study. CONCLUSION This study is an initial attempt at establishing local DRL values for digital radiography systems, and will provide a benchmark so that the authorities can establish reference dose levels for diagnostic radiology in Turkey. PMID:24317331

SU-E-I-33: Establishment of CT Diagnostic Reference Levels in Province Nova Scotia

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

Tonkopi, E; Abdolell, M; Duffy, S

2015-06-15

Purpose: To evaluate patient radiation dose from the most frequently performed CT examinations and to establish provincial diagnostic reference levels (DRLs) as a tool for protocol optimization. Methods: The study investigated the following CT examinations: head, chest, abdomen/pelvis, and chest/abdomen/pelvis (CAP). Dose data, volume CT dose index (CTDIvol) and dose-length product (DLP), were collected from 15 CT scanners installed during 2004–2014 in 11 hospital sites of Nova Scotia. All scanners had dose modulation options and multislice capability (16–128 detector rows). The sample for each protocol included 15 average size patients (70±20 kg). Provincial DRLs were calculated as the 75th percentilemore » of patient dose distributions. The differences in dose between hospitals were evaluated with a single factor ANOVA statistical test. Generalized linear modeling was used to determine the factors associated with higher radiation dose. A sample of 36 abdominal studies performed on three different scanners was blinded and randomized for an assessment by an experienced radiologist who graded the imaging quality of anatomic structures. Results: Data for 900 patients were collected. The DRLs were proposed using CTDIvol (mGy) and DLP (mGy*cm) values for CT head (67 and 1049, respectively), chest (12 and 393), abdomen/pelvis (16 and 717), and CAP (14 and 1034). These DRLs were lower than the published national data except for the head CTDIvol. The differences between the means of the dose distributions from each scanner were statistically significant (p<0.05) for all examinations. A very weak correlation was found between the dose and the scanner age or the number of slices with Pearson’s correlation coefficients of 0.011–0.315. The blinded analysis of image quality demonstrated no clinically significant difference except for the noise category. Conclusion: Provincial DRLs were established for typical CT examinations. The variations in dose between the hospitals suggested a large potential for optimization of examinations. Radiology Research Foundation grant.« less

Traditional medicine and gastroprotective crude drugs.

PubMed

Schmeda-Hirschmann, Guillermo; Yesilada, Erdem

2005-08-22

A frequent question when dealing with the search for gastroprotective compounds from natural sources is how far or close are both the plant preparations and extract amounts from the doses recommended in traditional medicine and what should be considered realistic levels for experimental studies. The administration way is oral and therefore extracts and products should be administered by gavage when looking for validation of ethnopharmacological uses. Suggestions of doses for both crude extracts and pure compounds are presented and discussed. For plant extracts prepared from single herbs and herbal mixtures, dose-response studies in the range between 100 and 300 mg/kg are suggested, with more than a single gastric ulcer model either in rats or mice. A suitable reference compound should be used according to the ulcer model and in doses resembling those used for human patients. For pure compounds and structure-activity studies or trends, dose-response results should be provided for at least a parent compound in order to select a reasonable dose for comparison purposes. We suggest an evaluation of the activity of the parent compound in the 50-300 mg/kg range and to look for structural modification leading to derivatives with similar or higher gastroprotective effects than the reference antiulcer compounds.

A strategy to optimize CT pediatric dose with a visual discrimination model

NASA Astrophysics Data System (ADS)

Gutierrez, Daniel; Gudinchet, François; Alamo-Maestre, Leonor T.; Bochud, François O.; Verdun, Francis R.

2008-03-01

Technological developments of computed tomography (CT) have led to a drastic increase of its clinical utilization, creating concerns about patient exposure. To better control dose to patients, we propose a methodology to find an objective compromise between dose and image quality by means of a visual discrimination model. A GE LightSpeed-Ultra scanner was used to perform the acquisitions. A QRM 3D low contrast resolution phantom (QRM - Germany) was scanned using CTDI vol values in the range of 1.7 to 103 mGy. Raw data obtained with the highest CTDI vol were afterwards processed to simulate dose reductions by white noise addition. Noise realism of the simulations was verified by comparing normalized noise power spectra aspect and amplitudes (NNPS) and standard deviation measurements. Patient images were acquired using the Diagnostic Reference Levels (DRL) proposed in Switzerland. Noise reduction was then simulated, as for the QRM phantom, to obtain five different CTDI vol levels, down to 3.0 mGy. Image quality of phantom images was assessed with the Sarnoff JNDmetrix visual discrimination model and compared to an assessment made by means of the ROC methodology, taken as a reference. For patient images a similar approach was taken but using as reference the Visual Grading Analysis (VGA) method. A relationship between Sarnoff JNDmetrix and ROC results was established for low contrast detection in phantom images, demonstrating that the Sarnoff JNDmetrix can be used for qualification of images with highly correlated noise. Patient image qualification showed a threshold of conspicuity loss only for children over 35 kg.

Predictors of Hyporesponsiveness to Erythropoiesis-Stimulating Agents in Hemodialysis Patients

PubMed Central

Kalantar-Zadeh, Kamyar; Lee, Grace H; Miller, Jessica E.; Streja, Elani; Jing, Jennie; Robertson, John A; Kovesdy, Csaba P.

2009-01-01

Background Identification of predictors of hyporesponsiveness to erythropoietin-stimulating agents (ESA) in hemodialysis (HD) patients may help improve anemia management and reduce hemoglobin variability. Study Design We conducted repeated measure and logistic regression analyses in a retrospective cohort of long-term HD patients to examine the association of iron markers and measures of renal osteodystrophy with ESA-responsiveness. The ESA-response coefficient at the individual level, i.e., the least-confounded dose-response association, was separated from the population level, assumed to represent confounding by medical indication. Setting/Participants The national database of a large dialysis organization (DaVita) with 38,328 surviving prevalent HD patients over 12 months, who received ESA for at least 3 consecutive calendar quarters, was examined. Predictors Serum levels of ferritin, iron saturation ratio (ISAT), intact parathyroid hormone (PTH) and alkaline phosphatase levels. Outcomes/Other Measurements The main outcome was case-mix adjusted hemoglobin response to quarterly averaged ESA dose at individual level. The odds ratio (OR) of the greatest vs. poorest ESA-response quartile at patient level was calculated. OR<1.0 indicated ESA hyporesponsiveness and OR>1.0 enhanced responsiveness. Results The mean (±SD) ESA-response coefficients of the least to most responsive quartiles were 0.301±0.033, 0.344±0.004, 0.357±0.004, and 0.389±0.026 g/dL higher hemoglobin per 1,000 units/week higher ESA dose in each quarter, respectively. The ORs of the greatest vs. poorest ESA-responsiveness at patient level were the following: Serum ferritin<200 ng/ml: 0.77 [95% confidence interval: 0.70–0.86] (reference: 200–500 ng/ml), ISAT<20%: 0.54 [0.49–0.59] (reference: 20–30%), intact PTH≥600 pg/ml: 0.54 [0.49–0.60] (reference: 150–300 pg/ml), and alkaline phosphatase ≥160 IU/L: 0.64 [0.58–0.70] (reference: 80–120 IU/L). Lower estimated dietary protein intake and serum levels of nutritional markers were also associated with higher risk of ESA-hyporesponsiveness. Limitations Our results may incorporate uncontrolled confounding. Achieved hemoglobin may have different associations than targeted hemoglobin. Conclusions In long-term HD patients, low iron stores, hyperparathyroidism and high turnover bone disease are associated with significant ESA-hyporesponsiveness. Prospective studies are needed to verify these associations. PMID:19339087

Trends in radiation exposure from clinical nuclear medicine procedures in Shanghai, China.

PubMed

Yi, Yanling; Zheng, Junzheng; Zhuo, Weihai; Gao, Linfeng

2012-03-01

This study was designed to assess the trends in the frequencies of nuclear medicine procedures in Shanghai, China, and to determine their contributions to the per capita effective dose to the Shanghai population. The mean activities of radionuclides administered by nuclear medicine departments were compared with the Chinese national guidelines on diagnostic reference levels. On the basis of the three surveys carried out by Shanghai Municipal Center for Disease Control and Prevention in 1996, 1998, and 2008, the typically administered radiopharmaceuticals, levels of activity, the number of procedures, and population were systematically analyzed to assess the frequencies of nuclear medicine procedures and the per capita effective dose. The frequencies were approximately 2.77, 3.46, and 6.63 per 1000 people in 1996, 1998, and 2008, respectively. The annual per capita doses from diagnostic nuclear medicine were estimated to be 0.016, 0.022, and 0.032 mSv in 1996, 1998, and 2008, respectively. The annual frequency of therapeutic nuclear medicine procedures increased from 0.131 to 0.430 per 1000 people in the intervening 12 years. In the 12 years before 2008, diagnostic and therapeutic procedures in nuclear medicine in Shanghai increased continuously, and the annual per capita dose doubled. Increases in PET imaging and bone scans were the major contributors to the increasing frequency and magnitude of radiation exposure to the population. The activities administered for most diagnostic procedures were generally consistent with the designated reference levels.

TU-G-204-05: The Effects of CT Acquisition and Reconstruction Conditions On Computed Texture Feature Values of Lung Lesions

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

Lo, P; Young, S; Kim, G

2015-06-15

Purpose: Texture features have been investigated as a biomarker of response and malignancy. Because these features reflect local differences in density, they may be influenced by acquisition and reconstruction parameters. The purpose of this study was to investigate the effects of radiation dose level and reconstruction method on features derived from lung lesions. Methods: With IRB approval, 33 lung tumor cases were identified from clinically indicated thoracic CT scans in which the raw projection (sinogram) data were available. Based on a previously-published technique, noise was added to the raw data to simulate reduced-dose versions of each case at 25%, 10%more » and 3% of the original dose. Original and simulated reduced dose projection data were reconstructed with conventional and two iterative-reconstruction settings, yielding 12 combinations of dose/recon conditions. One lesion from each case was contoured. At the reference condition (full dose, conventional recon), 17 lesions were randomly selected for repeat contouring (repeatability). For each lesion at each dose/recon condition, 151 texture measures were calculated. A paired differences approach was employed to compare feature variation from repeat contours at the reference condition to the variation observed in other dose/recon conditions (reproducibility). The ratio of standard deviation of the reproducibility to repeatability was used as the variation measure for each feature. Results: The mean variation (standard deviation) across dose levels and kernel was significantly different with a ratio of 2.24 (±5.85) across texture features (p=0.01). The mean variation (standard deviation) across dose levels with conventional recon was also significantly different with 2.30 (7.11) (p=0.025). The mean variation across reconstruction settings of original dose has a trend in showing difference with 1.35 (2.60) among all features (p=0.09). Conclusion: Texture features varied considerably with variations in dose and reconstruction condition. Care should be taken to standardize these conditions when using texture as a quantitative feature. This effort supported in part by a grant from the National Cancer Institute’s Quantitative Imaging Network (QIN): U01 CA181156; The UCLA Department of Radiology has a Master Research Agreement with Siemens Healthcare; Dr. McNitt-Gray has previously received research support from Siemens Healthcare.« less

Booster dose vaccination for preventing hepatitis B.

PubMed

Poorolajal, Jalal; Hooshmand, Elham

2016-06-07

Antibodies against hepatitis B surface antigen (HBsAg) wane over time following hepatitis B immunisation; hence, it is unclear whether people vaccinated in three-dose or four-dose schedules of the hepatitis B vaccine are still immune when the hepatitis B surface antibody (anti-HBs) level in their body is undetectable, or lower than the level usually considered protective. This question may potentially be answered indirectly by measuring the anamnestic immune response to a booster dose of vaccine. The term 'booster' (or revaccination) refers to an additional dose of hepatitis B vaccine (HBV) given some time post-primary vaccination to induce immune memory and improve protection against hepatitis B virus (HBV) infection. To assess the benefits and harms of booster dose hepatitis B vaccination, more than five years after the primary vaccination, for preventing HBV infection in healthy individuals previously vaccinated with the hepatitis B vaccine, and with hepatitis B surface antibody (anti-HBs) levels below 10 mIU/mL. We searched the Cochrane Hepato-Biliary Group Controlled Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, Science Citation Index Expanded, conference databases, and reference lists of articles to January 2016. We also contacted authors of articles. In addition, we searched ClinicalTrials.gov and the World Health Organization (WHO) International Clinical Trials Registry Platform for ongoing trials (May 2016). Randomised clinical trials addressing anamnestic immune response to a booster dose of hepatitis B vaccine, more than five years after the primary vaccination, in apparently healthy participants, vaccinated in a three-dose or four-dose schedule of the hepatitis B vaccine during the primary vaccination, without receiving an additional dose or immunoglobulin. Both review authors decided if the identified studies met the inclusion criteria or not. Primary outcomes included the proportion of participants with anamnestic immune response in non-protected participants and signs of HBV infection. Secondary outcomes were the proportion of participants that developed local and systemic adverse events following a booster dose injection. We planned to report the weighted proportion with 95% confidence intervals (CIs). There were no eligible randomised clinical trials fulfilling the inclusion criteria of this review. We were unable to include any randomised clinical trials on the topic; only randomised clinical trials will be able to provide an answer as to whether a booster dose vaccination is able to protect against hepatitis B infection.

Generative Adversarial Networks for Noise Reduction in Low-Dose CT.

PubMed

Wolterink, Jelmer M; Leiner, Tim; Viergever, Max A; Isgum, Ivana

2017-12-01

Noise is inherent to low-dose CT acquisition. We propose to train a convolutional neural network (CNN) jointly with an adversarial CNN to estimate routine-dose CT images from low-dose CT images and hence reduce noise. A generator CNN was trained to transform low-dose CT images into routine-dose CT images using voxelwise loss minimization. An adversarial discriminator CNN was simultaneously trained to distinguish the output of the generator from routine-dose CT images. The performance of this discriminator was used as an adversarial loss for the generator. Experiments were performed using CT images of an anthropomorphic phantom containing calcium inserts, as well as patient non-contrast-enhanced cardiac CT images. The phantom and patients were scanned at 20% and 100% routine clinical dose. Three training strategies were compared: the first used only voxelwise loss, the second combined voxelwise loss and adversarial loss, and the third used only adversarial loss. The results showed that training with only voxelwise loss resulted in the highest peak signal-to-noise ratio with respect to reference routine-dose images. However, CNNs trained with adversarial loss captured image statistics of routine-dose images better. Noise reduction improved quantification of low-density calcified inserts in phantom CT images and allowed coronary calcium scoring in low-dose patient CT images with high noise levels. Testing took less than 10 s per CT volume. CNN-based low-dose CT noise reduction in the image domain is feasible. Training with an adversarial network improves the CNNs ability to generate images with an appearance similar to that of reference routine-dose CT images.

Protection of the public in situations of prolonged radiation exposure. The application of the Commission's system of radiological protection to controllable radiation exposure due to natural sources and long-lived radioactive residues.

PubMed

1999-01-01

This report provides guidance on the application of the ICRP system of radiological protection to prolonged exposure situations affecting members of the public. It addresses the general application of the Commission's system to the control of prolonged exposures resulting from practices and to the undertaking of interventions in prolonged exposure situations. Additionally, it provides recommendations on generic reference levels for such interventions. The report also considers some specific situations and discusses a number of issues that have been of concern, namely: natural radiation sources that may give rise to high doses; the restoration and rehabilitation of sites where human activities involving radioactive substances have been carried out; the return to 'normality' following an accident that has released radioactive substances to the environment; and the global marketing of commodities for public consumption that contain radioactive substances. Annexes provide some examples of prolonged exposure situations and discuss the radiological protection quantities, radiation-induced health effects and aspects of the Commission's system of radiological protection relevant to prolonged exposure. Quantitative recommendations for prolonged exposures are provided in the report. They must be interpreted with extreme caution; Chapters 4 and 5 stress the upper bound nature of the following values: Generic reference levels for intervention, in terms of existing total annual doses, are given as < approximately 100 mSv, above which intervention is almost always justifiable (situations for which the annual dose threshold for deterministic effects in relevant organs is exceeded will almost always require intervention), and < approximately 10 mSv, below which intervention is not likely to be justifiable (and above which it may be necessary). Intervention exemption levels for commodities, especially building materials, are expressed as an additional annual dose of approximately 1 mSv. The dose limit for exposures of the public from practices is expressed as aggregated (prolonged and transitory) additional annual doses from all relevant practices of 1 mSv. Dose constraints for sources within practices are expressed as an additional annual dose lower than 1 mSv (e.g. of approximately 0.3 mSv), which could be approximately 0.1 mSv for the prolonged exposure component. An exemption level for practices is expressed as an additional annual dose of approximately 0.01 mSv.

The FLUKA Monte Carlo code coupled with the NIRS approach for clinical dose calculations in carbon ion therapy

NASA Astrophysics Data System (ADS)

Magro, G.; Dahle, T. J.; Molinelli, S.; Ciocca, M.; Fossati, P.; Ferrari, A.; Inaniwa, T.; Matsufuji, N.; Ytre-Hauge, K. S.; Mairani, A.

2017-05-01

Particle therapy facilities often require Monte Carlo (MC) simulations to overcome intrinsic limitations of analytical treatment planning systems (TPS) related to the description of the mixed radiation field and beam interaction with tissue inhomogeneities. Some of these uncertainties may affect the computation of effective dose distributions; therefore, particle therapy dedicated MC codes should provide both absorbed and biological doses. Two biophysical models are currently applied clinically in particle therapy: the local effect model (LEM) and the microdosimetric kinetic model (MKM). In this paper, we describe the coupling of the NIRS (National Institute for Radiological Sciences, Japan) clinical dose to the FLUKA MC code. We moved from the implementation of the model itself to its application in clinical cases, according to the NIRS approach, where a scaling factor is introduced to rescale the (carbon-equivalent) biological dose to a clinical dose level. A high level of agreement was found with published data by exploring a range of values for the MKM input parameters, while some differences were registered in forward recalculations of NIRS patient plans, mainly attributable to differences with the analytical TPS dose engine (taken as reference) in describing the mixed radiation field (lateral spread and fragmentation). We presented a tool which is being used at the Italian National Center for Oncological Hadrontherapy to support the comparison study between the NIRS clinical dose level and the LEM dose specification.

A framework for estimating radiation-related cancer risks in Japan from the 2011 Fukushima nuclear accident.

PubMed

Walsh, L; Zhang, W; Shore, R E; Auvinen, A; Laurier, D; Wakeford, R; Jacob, P; Gent, N; Anspaugh, L R; Schüz, J; Kesminiene, A; van Deventer, E; Tritscher, A; del Rosarion Pérez, M

2014-11-01

We present here a methodology for health risk assessment adopted by the World Health Organization that provides a framework for estimating risks from the Fukushima nuclear accident after the March 11, 2011 Japanese major earthquake and tsunami. Substantial attention has been given to the possible health risks associated with human exposure to radiation from damaged reactors at the Fukushima Daiichi nuclear power station. Cumulative doses were estimated and applied for each post-accident year of life, based on a reference level of exposure during the first year after the earthquake. A lifetime cumulative dose of twice the first year dose was estimated for the primary radionuclide contaminants ((134)Cs and (137)Cs) and are based on Chernobyl data, relative abundances of cesium isotopes, and cleanup efforts. Risks for particularly radiosensitive cancer sites (leukemia, thyroid and breast cancer), as well as the combined risk for all solid cancers were considered. The male and female cumulative risks of cancer incidence attributed to radiation doses from the accident, for those exposed at various ages, were estimated in terms of the lifetime attributable risk (LAR). Calculations of LAR were based on recent Japanese population statistics for cancer incidence and current radiation risk models from the Life Span Study of Japanese A-bomb survivors. Cancer risks over an initial period of 15 years after first exposure were also considered. LAR results were also given as a percentage of the lifetime baseline risk (i.e., the cancer risk in the absence of radiation exposure from the accident). The LAR results were based on either a reference first year dose (10 mGy) or a reference lifetime dose (20 mGy) so that risk assessment may be applied for relocated and non-relocated members of the public, as well as for adult male emergency workers. The results show that the major contribution to LAR from the reference lifetime dose comes from the first year dose. For a dose of 10 mGy in the first year and continuing exposure, the lifetime radiation-related cancer risks based on lifetime dose (which are highest for children under 5 years of age at initial exposure), are small, and much smaller than the lifetime baseline cancer risks. For example, after initial exposure at age 1 year, the lifetime excess radiation risk and baseline risk of all solid cancers in females were estimated to be 0.7 · 10(-2) and 29.0 · 10(-2), respectively. The 15 year risks based on the lifetime reference dose are very small. However, for initial exposure in childhood, the 15 year risks based on the lifetime reference dose are up to 33 and 88% as large as the 15 year baseline risks for leukemia and thyroid cancer, respectively. The results may be scaled to particular dose estimates after consideration of caveats. One caveat is related to the lack of epidemiological evidence defining risks at low doses, because the predicted risks come from cancer risk models fitted to a wide dose range (0-4 Gy), which assume that the solid cancer and leukemia lifetime risks for doses less than about 0.5 Gy and 0.2 Gy, respectively, are proportional to organ/tissue doses: this is unlikely to seriously underestimate risks, but may overestimate risks. This WHO-HRA framework may be used to update the risk estimates, when new population health statistics data, dosimetry information and radiation risk models become available.

A chronic oral reference dose for hexavalent chromium-induced intestinal cancer†

PubMed Central

Thompson, Chad M; Kirman, Christopher R; Proctor, Deborah M; Haws, Laurie C; Suh, Mina; Hays, Sean M; Hixon, J Gregory; Harris, Mark A

2014-01-01

High concentrations of hexavalent chromium [Cr(VI)] in drinking water induce villous cytotoxicity and compensatory crypt hyperplasia in the small intestines of mice (but not rats). Lifetime exposure to such cytotoxic concentrations increases intestinal neoplasms in mice, suggesting that the mode of action for Cr(VI)-induced intestinal tumors involves chronic wounding and compensatory cell proliferation of the intestine. Therefore, we developed a chronic oral reference dose (RfD) designed to be protective of intestinal damage and thus intestinal cancer. A physiologically based pharmacokinetic model for chromium in mice was used to estimate the amount of Cr(VI) entering each intestinal tissue section (duodenum, jejunum and ileum) from the lumen per day (normalized to intestinal tissue weight). These internal dose metrics, together with corresponding incidences for diffuse hyperplasia, were used to derive points of departure using benchmark dose modeling and constrained nonlinear regression. Both modeling techniques resulted in similar points of departure, which were subsequently converted to human equivalent doses using a human physiologically based pharmacokinetic model. Applying appropriate uncertainty factors, an RfD of 0.006 mg kg–1 day–1 was derived for diffuse hyperplasia—an effect that precedes tumor formation. This RfD is protective of both noncancer and cancer effects in the small intestine and corresponds to a safe drinking water equivalent level of 210 µg l–1. This concentration is higher than the current federal maximum contaminant level for total Cr (100 µg l–1) and well above levels of Cr(VI) in US drinking water supplies (typically ≤ 5 µg l–1). © 2013 The Authors. Journal of Applied Toxicology published by John Wiley & Sons, Ltd. PMID:23943231

Sci-Thur PM – Colourful Interactions: Highlights 07: Canadian Computed Tomography Survey: National Diagnostic Reference Levels

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

Wardlaw, Graeme M; Martel, Narine

Purpose: The Canadian Computed (CT) Tomography Survey sought to collect CT technology and dose index data (CTDI and DLP) at the national level in order to establish national diagnostic reference levels (DRLs) for seven common CT examinations of standard-sized adults and pediatric patients. Methods: A single survey booklet (consisting of four sections) was mailed to and completed for each participating CT scanner. Survey sections collected data on (i) General facility and scanner information, (ii) routine protocols (as available), (iii) individual patient data (as applied) and (iv) manual CTDI measurements. Results: Dose index (CTDIvol and DLP) and associated patient data frommore » 24 280 individual patient exam sequences was analyzed for seven common CT examinations performed in Canada: Adult Head, Chest, Abdomen/Pelvis, and Chest/Abdomen/Pelvis, and Pediatric Head, Chest, and Abdomen. Pediatric examination data was sub-divided into three age ranges: 0–3, 3–7 and 7–13 years. DRLs (75th percentile of dose index distributions) were found for all thirteen groups. Further analysis also permitted segmentation of examination data into 8 sub-groups, whose dose index data was displayed along with group histograms – showing relative contribution of axial vs. helical, contrast use (C+ vs. C-), and application of fixed current vs. dose reduction (DR) – 75th percentiles of DR sub-groups were, in almost all cases, lower than whole group (examination) DRLs. Conclusions: The analysis and summaries presented in the pending survey report can serve to aid local CT imaging optimization efforts within Canada and also contribute further to international efforts in radiation protection of patients.« less

131I-tositumomab myeloablative radioimmunotherapy for non-Hodgkin’s lymphoma: radiation dose to the testes

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

Hattori, Naoya; Gopal, Ajay K.; Shields, Andrew T.

Purpose: To investigate radiation doses to the testes delivered by a radiolabeled anti-CD20 antibody and its effects on male sex hormone levels. Materials and methods: Testicular uptake and retention of 131I-tositumomab were measured, and testicular absorbed doses were calculated for 67 male patients (54+/-11 years of age) with non-Hodgkin's lymphoma who had undergone myeloablative radioimmunotherapy (RIT) using 131I-tositumomab. Time-activity curves for the major organs, testes, and whole body were generated from planar imaging studies. In a subset of patients, male sex hormones were measured before and 1 year after the therapy. Results: The absorbed dose to the testes showed considerablemore » variability (range=4.4-70.2 Gy). Pretherapy levels of total testosterone were below the lower limit of the reference range, and post-therapy evaluation demonstrated further reduction [4.6+/-1.8 nmol/l (pre-RIT) vs. 3.8+/-2.9 nmol/l (post-RIT), P<0.05]. Patients receiving higher radiation doses to the testes (>=25 Gy) showed a greater reduction [4.7+/-1.6 nmol/l (pre-RIT) vs. 3.3+/-2.7 nmol/l (post-RIT), P<0.05] compared with patients receiving lower doses (<25 Gy), who showed no significant change in total testosterone levels. Conclusion: The testicular radiation absorbed dose varied highly among individual patients. Finally, patients receiving higher doses to the testes were more likely to show post-RIT suppression of testosterone levels.« less

Radiation dose in coronary angiography and intervention: initial results from the establishment of a multi-centre diagnostic reference level in Queensland public hospitals

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

Crowhurst, James A, E-mail: jimcrowhurst@hotmail.com; School of Medicine, University of Queensland, St. Lucia, Brisbane, Queensland; Whitby, Mark

Radiation dose to patients undergoing invasive coronary angiography (ICA) is relatively high. Guidelines suggest that a local benchmark or diagnostic reference level (DRL) be established for these procedures. This study sought to create a DRL for ICA procedures in Queensland public hospitals. Data were collected for all Cardiac Catheter Laboratories in Queensland public hospitals. Data were collected for diagnostic coronary angiography (CA) and single-vessel percutaneous intervention (PCI) procedures. Dose area product (P{sub KA}), skin surface entrance dose (K{sub AR}), fluoroscopy time (FT), and patient height and weight were collected for 3 months. The DRL was set from the 75th percentilemore » of the P{sub KA.} 2590 patients were included in the CA group where the median FT was 3.5 min (inter-quartile range = 2.3–6.1). Median K{sub AR} = 581 mGy (374–876). Median P{sub KA} = 3908 uGym{sup 2} (2489–5865) DRL = 5865 uGym{sup 2}. 947 patients were included in the PCI group where median FT was 11.2 min (7.7–17.4). Median K{sub AR} = 1501 mGy (928–2224). Median P{sub KA} = 8736 uGym{sup 2} (5449–12,900) DRL = 12,900 uGym{sup 2}. This study established a benchmark for radiation dose for diagnostic and interventional coronary angiography in Queensland public facilities.« less

Patient dose in interventional radiology: a multicentre study of the most frequent procedures in France.

PubMed

Etard, Cécile; Bigand, Emeline; Salvat, Cécile; Vidal, Vincent; Beregi, Jean Paul; Hornbeck, Amaury; Greffier, Joël

2017-10-01

A national retrospective survey on patient doses was performed by the French Society of Medical physicists to assess reference levels (RLs) in interventional radiology as required by the European Directive 2013/59/Euratom. Fifteen interventional procedures in neuroradiology, vascular radiology and osteoarticular procedures were analysed. Kerma area product (KAP), fluoroscopy time (FT), reference air kerma and number of images were recorded for 10 to 30 patients per procedure. RLs were calculated as the 3rd quartiles of the distributions. Results on 4600 procedures from 36 departments confirmed the large variability in patient dose for the same procedure. RLs were proposed for the four dosimetric estimators and the 15 procedures. RLs in terms of KAP and FT were 90 Gm.cm 2 and 11 mins for cerebral angiography, 35 Gy.cm 2 and 16 mins for biliary drainage, 75 Gy.cm 2 and 6 mins for lower limbs arteriography and 70 Gy.cm 2 and 11 mins for vertebroplasty. For these four procedures, RLs were defined according to the complexity of the procedure. For all the procedures, the results were lower than most of those already published. This study reports RLs in interventional radiology based on a national survey. Continual evolution of practices and technologies requires regular updates of RLs. • Delivered dose in interventional radiology depends on procedure, practice and patient. • National RLs are proposed for 15 interventional procedures. • Reference levels (RLs) are useful to benchmark practices and optimize protocols. • RLs are proposed for kerma area product, air kerma, fluoroscopy time and number of images. • RLs should be adapted to the procedure complexity and updated regularly.

Environmental radiology assessment in Lahad Datu, Sabah

NASA Astrophysics Data System (ADS)

Siti Fharhana, Yusof; Wan Muhamad Saridan, Wan Hassan; Ahmad Termizi, Ramli; Mohd Hilmi, Sahini; Mohammad Syazwan, Mohd Sanusi; Nor Afifah, Basri; Nor Zati Hani, Abu Hanifah

2017-10-01

Monitoring terrestial gamma radiation is crucial to prepare a baseline data for environmental radiological protection. Radiological research was carried out in Lahad Datu, Sabah to obtain the radioactivity status and terrestrial gamma radiation level in the area. We measure the terrestrial gamma radiation dose rates and analyse the radioactivity concentration of primordial radionuclides for radiological risk assessment. We identified that the annual estimation of dose effective for public is below the public dose limit, 1 mSv per year. Public and environment safety and health are remain secure. The obtained data and results can be used as reference for environmental radiology protection.

Relationships between patient size, dose and image noise under automatic tube current modulation systems.

PubMed

Sookpeng, S; Martin, C J; Gentle, D J; Lopez-Gonzalez, M R

2014-03-01

Automatic tube current modulation (ATCM) systems are now used for the majority of CT scans. The principles of ATCM operation are different in CT scanners from different manufacturers. Toshiba and GE scanners base the current modulation on a target noise setting, while Philips and Siemens scanners use reference image and reference mAs concepts respectively. Knowledge of the relationships between patient size, dose and image noise are important for CT patient dose optimisation. In this study, the CT patient doses were surveyed for 14 CT scanners from four different CT scanner manufacturers. The patient cross sectional area, the tube current modulation and the image noise from the CT images were analysed using in-house software. The Toshiba and GE scanner results showed that noise levels are relatively constant but tube currents are dependent on patient size. As a result of this there is a wide range in tube current values across different patient sizes, and doses for large patients are significantly higher in these scanners. In contrast, in the Philips and Siemens scanners, tube currents are less dependent on patient size, the range in tube current is narrower, and the doses for larger patients are not as high. Image noise is more dependent on the patient size.

Dose-Response Modelling of Paralytic Shellfish Poisoning (PSP) in Humans

PubMed Central

Arnich, Nathalie; Thébault, Anne

2018-01-01

Paralytic shellfish poisoning (PSP) is caused by a group of marine toxins with saxitoxin (STX) as the reference compound. Symptoms in humans after consumption of contaminated shellfish vary from slight neurological and gastrointestinal effects to fatal respiratory paralysis. A systematic review was conducted to identify reported cases of human poisoning associated with the ingestion of shellfish contaminated with paralytic shellfish toxins (PSTs). Raw data were collected from 143 exposed individuals (113 with symptoms, 30 without symptoms) from 13 studies. Exposure estimates were based on mouse bioassays except in one study. A significant relationship between exposure to PSTs and severity of symptoms was established by ordinal modelling. The critical minimal dose with a probability higher than 10% of showing symptoms is 0.37 µg STX eq./kg b.w. This means that 10% of the individuals exposed to this dose would have symptoms (without considering the severity of the symptoms). This dose is four-fold lower than the lowest-observed-adverse-effect-level (LOAEL) established by the European Food Safety Authority (EFSA, 2009) in the region of 1.5 μg STX eq./kg b.w. This work provides critical doses that could be used as point of departure to update the acute reference dose for STX. This is the first time a dose-symptoms model could be built for marine toxins using epidemiological data. PMID:29597338

In vitro evaluation of a new iterative reconstruction algorithm for dose reduction in coronary artery calcium scoring

PubMed Central

Allmendinger, Thomas; Kunz, Andreas S; Veyhl-Wichmann, Maike; Ergün, Süleyman; Bley, Thorsten A; Petritsch, Bernhard

2017-01-01

Background Coronary artery calcium (CAC) scoring is a widespread tool for cardiac risk assessment in asymptomatic patients and accompanying possible adverse effects, i.e. radiation exposure, should be as low as reasonably achievable. Purpose To evaluate a new iterative reconstruction (IR) algorithm for dose reduction of in vitro coronary artery calcium scoring at different tube currents. Material and Methods An anthropomorphic calcium scoring phantom was scanned in different configurations simulating slim, average-sized, and large patients. A standard calcium scoring protocol was performed on a third-generation dual-source CT at 120 kVp tube voltage. Reference tube current was 80 mAs as standard and stepwise reduced to 60, 40, 20, and 10 mAs. Images were reconstructed with weighted filtered back projection (wFBP) and a new version of an established IR kernel at different strength levels. Calcifications were quantified calculating Agatston and volume scores. Subjective image quality was visualized with scans of an ex vivo human heart. Results In general, Agatston and volume scores remained relatively stable between 80 and 40 mAs and increased at lower tube currents, particularly in the medium and large phantom. IR reduced this effect, as both Agatston and volume scores decreased with increasing levels of IR compared to wFBP (P < 0.001). Depending on selected parameters, radiation dose could be lowered by up to 86% in the large size phantom when selecting a reference tube current of 10 mAs with resulting Agatston levels close to the reference settings. Conclusion New iterative reconstruction kernels may allow for reduction in tube current for established Agatston scoring protocols and consequently for substantial reduction in radiation exposure. PMID:28607763

A dose comparison survey in CT departments of dedicated paediatric hospitals in Australia and Saudi Arabia

PubMed Central

Mohiy, Hussain Al; Sim, Jenny; Seeram, Euclid; Annabell, Nathan; Geso, Moshi; Mandarano, Giovanni; Davidson, Rob

2012-01-01

AIM: To measure and compare computed tomography (CT) radiation doses delivered to patients in public paediatric hospitals in Australia and Saudi Arabia. METHODS: Doses were measured for routine CT scans of the head, chest and abdomen/pelvis for children aged 3-6 years in all dedicated public paediatric hospitals in Australia and Saudi Arabia using a CT phantom measurement cylinder. RESULTS: CT doses, using the departments’ protocols for 3-6 year old, varied considerably between hospitals. Measured head doses varied from 137.6 to 528.0 mGy·cm, chest doses from 21.9 to 92.5 mGy·cm, and abdomen/pelvis doses from 24.9 to 118.0 mGy·cm. Mean head and abdomen/pelvis doses delivered in Saudi Arabian paediatric CT departments were significantly higher than those in their Australian equivalents. CONCLUSION: CT dose varies substantially across Australian and Saudi Arabian paediatric hospitals. Therefore, diagnostic reference levels should be established for major anatomical regions to standardise dose. PMID:23150767

TH-C-18A-08: A Management Tool for CT Dose Monitoring, Analysis, and Protocol Review

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

Wang, J; Chan, F; Newman, B

2014-06-15

Purpose: To develop a customizable tool for enterprise-wide managing of CT protocols and analyzing radiation dose information of CT exams for a variety of quality control applications Methods: All clinical CT protocols implemented on the 11 CT scanners at our institution were extracted in digital format. The original protocols had been preset by our CT management team. A commercial CT dose tracking software (DoseWatch,GE healthcare,WI) was used to collect exam information (exam date, patient age etc.), scanning parameters, and radiation doses for all CT exams. We developed a Matlab-based program (MathWorks,MA) with graphic user interface which allows to analyze themore » scanning protocols with the actual dose estimates, and compare the data to national (ACR,AAPM) and internal reference values for CT quality control. Results: The CT protocol review portion of our tool allows the user to look up the scanning and image reconstruction parameters of any protocol on any of the installed CT systems among about 120 protocols per scanner. In the dose analysis tool, dose information of all CT exams (from 05/2013 to 02/2014) was stratified on a protocol level, and within a protocol down to series level, i.e. each individual exposure event. This allows numerical and graphical review of dose information of any combination of scanner models, protocols and series. The key functions of the tool include: statistics of CTDI, DLP and SSDE, dose monitoring using user-set CTDI/DLP/SSDE thresholds, look-up of any CT exam dose data, and CT protocol review. Conclusion: our inhouse CT management tool provides radiologists, technologists and administration a first-hand near real-time enterprise-wide knowledge on CT dose levels of different exam types. Medical physicists use this tool to manage CT protocols, compare and optimize dose levels across different scanner models. It provides technologists feedback on CT scanning operation, and knowledge on important dose baselines and thresholds.« less

Evaluation of triclosan in Minnesota lakes and rivers: Part II - human health risk assessment.

PubMed

Yost, Lisa J; Barber, Timothy R; Gentry, P Robinan; Bock, Michael J; Lyndall, Jennifer L; Capdevielle, Marie C; Slezak, Brian P

2017-08-01

Triclosan, an antimicrobial compound found in consumer products, has been detected in low concentrations in Minnesota municipal wastewater treatment plant (WWTP) effluent. This assessment evaluates potential health risks for exposure of adults and children to triclosan in Minnesota surface water, sediments, and fish. Potential exposures via fish consumption are considered for recreational or subsistence-level consumers. This assessment uses two chronic oral toxicity benchmarks, which bracket other available toxicity values. The first benchmark is a lower bound on a benchmark dose associated with a 10% risk (BMDL 10 ) of 47mg per kilogram per day (mg/kg-day) for kidney effects in hamsters. This value was identified as the most sensitive endpoint and species in a review by Rodricks et al. (2010) and is used herein to derive an estimated reference dose (RfD (Rodricks) ) of 0.47mg/kg-day. The second benchmark is a reference dose (RfD) of 0.047mg/kg-day derived from a no observed adverse effect level (NOAEL) of 10mg/kg-day for hepatic and hematopoietic effects in mice (Minnesota Department of Health [MDH] 2014). Based on conservative assumptions regarding human exposures to triclosan, calculated risk estimates are far below levels of concern. These estimates are likely to overestimate risks for potential receptors, particularly because sample locations were generally biased towards known discharges (i.e., WWTP effluent). Copyright © 2017 Elsevier Inc. All rights reserved.

Development of a chronic noncancer oral reference dose and drinking water screening level for sulfolane using benchmark dose modeling.

PubMed

Thompson, Chad M; Gaylor, David W; Tachovsky, J Andrew; Perry, Camarie; Carakostas, Michael C; Haws, Laurie C

2013-12-01

Sulfolane is a widely used industrial solvent that is often used for gas treatment (sour gas sweetening; hydrogen sulfide removal from shale and coal processes, etc.), and in the manufacture of polymers and electronics, and may be found in pharmaceuticals as a residual solvent used in the manufacturing processes. Sulfolane is considered a high production volume chemical with worldwide production around 18 000-36 000 tons per year. Given that sulfolane has been detected as a contaminant in groundwater, an important potential route of exposure is tap water ingestion. Because there are currently no federal drinking water standards for sulfolane in the USA, we developed a noncancer oral reference dose (RfD) based on benchmark dose modeling, as well as a tap water screening value that is protective of ingestion. Review of the available literature suggests that sulfolane is not likely to be mutagenic, clastogenic or carcinogenic, or pose reproductive or developmental health risks except perhaps at very high exposure concentrations. RfD values derived using benchmark dose modeling were 0.01-0.04 mg kg(-1) per day, although modeling of developmental endpoints resulted in higher values, approximately 0.4 mg kg(-1) per day. The lowest, most conservative, RfD of 0.01 mg kg(-1) per day was based on reduced white blood cell counts in female rats. This RfD was used to develop a tap water screening level that is protective of ingestion, viz. 365 µg l(-1). It is anticipated that these values, along with the hazard identification and dose-response modeling described herein, should be informative for risk assessors and regulators interested in setting health-protective drinking water guideline values for sulfolane. Copyright © 2012 John Wiley & Sons, Ltd.

Chemical-specific screening criteria for interpretation of biomonitoring data for volatile organic compounds (VOCs)--application of steady-state PBPK model solutions.

PubMed

Aylward, Lesa L; Kirman, Chris R; Blount, Ben C; Hays, Sean M

2010-10-01

The National Health and Nutrition Examination Survey (NHANES) generates population-representative biomonitoring data for many chemicals including volatile organic compounds (VOCs) in blood. However, no health or risk-based screening values are available to evaluate these data from a health safety perspective or to use in prioritizing among chemicals for possible risk management actions. We gathered existing risk assessment-based chronic exposure reference values such as reference doses (RfDs), reference concentrations (RfCs), tolerable daily intakes (TDIs), cancer slope factors, etc. and key pharmacokinetic model parameters for 47 VOCs. Using steady-state solutions to a generic physiologically-based pharmacokinetic (PBPK) model structure, we estimated chemical-specific steady-state venous blood concentrations across chemicals associated with unit oral and inhalation exposure rates and with chronic exposure at the identified exposure reference values. The geometric means of the slopes relating modeled steady-state blood concentrations to steady-state exposure to a unit oral dose or unit inhalation concentration among 38 compounds with available pharmacokinetic parameters were 12.0 microg/L per mg/kg-d (geometric standard deviation [GSD] of 3.2) and 3.2 microg/L per mg/m(3) (GSD=1.7), respectively. Chemical-specific blood concentration screening values based on non-cancer reference values for both oral and inhalation exposure range from 0.0005 to 100 microg/L; blood concentrations associated with cancer risk-specific doses at the 1E-05 risk level ranged from 5E-06 to 6E-02 microg/L. The distribution of modeled steady-state blood concentrations associated with unit exposure levels across VOCs may provide a basis for estimating blood concentration screening values for VOCs that lack chemical-specific pharmacokinetic data. The screening blood concentrations presented here provide a tool for risk assessment-based evaluation of population biomonitoring data for VOCs and are most appropriately applied to central tendency estimates for such datasets. Copyright (c) 2010 Elsevier Inc. All rights reserved.

The effect of radiation dose reduction on computer-aided detection (CAD) performance in a low-dose lung cancer screening population.

PubMed

Young, Stefano; Lo, Pechin; Kim, Grace; Brown, Matthew; Hoffman, John; Hsu, William; Wahi-Anwar, Wasil; Flores, Carlos; Lee, Grace; Noo, Frederic; Goldin, Jonathan; McNitt-Gray, Michael

2017-04-01

Lung cancer screening with low-dose CT has recently been approved for reimbursement, heralding the arrival of such screening services worldwide. Computer-aided detection (CAD) tools offer the potential to assist radiologists in detecting nodules in these screening exams. In lung screening, as in all CT exams, there is interest in further reducing radiation dose. However, the effects of continued dose reduction on CAD performance are not fully understood. In this work, we investigated the effect of reducing radiation dose on CAD lung nodule detection performance in a screening population. The raw projection data files were collected from 481 patients who underwent low-dose screening CT exams at our institution as part of the National Lung Screening Trial (NLST). All scans were performed on a multidetector scanner (Sensation 64, Siemens Healthcare, Forchheim Germany) according to the NLST protocol, which called for a fixed tube current scan of 25 effective mAs for standard-sized patients and 40 effective mAs for larger patients. The raw projection data were input to a reduced-dose simulation software to create simulated reduced-dose scans corresponding to 50% and 25% of the original protocols. All raw data files were reconstructed at the scanner with 1 mm slice thickness and B50 kernel. The lungs were segmented semi-automatically, and all images and segmentations were input to an in-house CAD algorithm trained on higher dose scans (75-300 mAs). CAD findings were compared to a reference standard generated by an experienced reader. Nodule- and patient-level sensitivities were calculated along with false positives per scan, all of which were evaluated in terms of the relative change with respect to dose. Nodules were subdivided based on size and solidity into categories analogous to the LungRADS assessment categories, and sub-analyses were performed. From the 481 patients in this study, 82 had at least one nodule (prevalence of 17%) and 399 did not (83%). A total of 118 nodules were identified. Twenty-seven nodules (23%) corresponded to LungRADS category 4 based on size and composition, while 18 (15%) corresponded to LungRADS category 3 and 73 (61%) corresponded to LungRADS category 2. For solid nodules ≥8 mm, patient-level median sensitivities were 100% at all three dose levels, and mean sensitivities were 72%, 63%, and 63% at original, 50%, and 25% dose, respectively. Overall mean patient-level sensitivities for nodules ranging from 3 to 45 mm were 38%, 37%, and 38% at original, 50%, and 25% dose due to the prevalence of smaller nodules and nonsolid nodules in our reference standard. The mean false-positive rates were 3, 5, and 13 per case. CAD sensitivity decreased very slightly for larger nodules as dose was reduced, indicating that reducing the dose to 50% of original levels may be investigated further for use in CT screening. However, the effect of dose was small relative to the effect of the nodule size and solidity characteristics. The number of false positives per scan increased substantially at 25% dose, illustrating the importance of tuning CAD algorithms to very challenging, high-noise screening exams. © 2017 American Association of Physicists in Medicine.

Urinary calculi composed of uric acid, cystine, and mineral salts: differentiation with dual-energy CT at a radiation dose comparable to that of intravenous pyelography.

PubMed

Thomas, Christoph; Heuschmid, Martin; Schilling, David; Ketelsen, Dominik; Tsiflikas, Ilias; Stenzl, Arnulf; Claussen, Claus D; Schlemmer, Heinz-Peter

2010-11-01

To retrospectively evaluate radiation dose, image quality, and the ability to differentiate urinary calculi of differing compositions by using low-dose dual-energy computed tomography (CT). The institutional review board approved this retrospective study; informed consent was waived. A low-dose dual-energy CT protocol (tube voltage and reference effective tube current-time product, 140 kV and 23 mAs and 80 kV and 105 mAs; collimation, 64 × 0.6 mm; pitch, 0.7) for the detection of urinary calculi was implemented into routine clinical care. All patients (n = 112) who were examined with this protocol from July 2008 to August 2009 were included. The composition of urinary calculi was assessed by using commercially available postprocessing software and was compared with results of the reference standard (ex vivo infrared spectroscopy) in 40 patients for whom the reference standard was available. Effective doses were calculated. Image quality was rated subjectively and objectively and was correlated with patient size expressed as body cross-sectional area at the level of acquisition by using Spearman correlation coefficients. One calcified concrement in the distal ureter of an obese patient was mistakenly interpreted as mixed calcified and uric acid. One struvite calculus was falsely interpreted as cystine. All other uric acid, cystine, and calcium-containing calculi were correctly identified by using dual-energy CT. The mean radiation dose was 2.7 mSv. The average image quality was rated as acceptable, with a decrease in image quality in larger patients. Low-dose unenhanced dual-source dual-energy CT can help differentiate between calcified, uric acid, and cystine calculi at a radiation dose comparable to that of conventional intravenous pyelography. Because of decreased image quality in obese patients, only nonobese patients should be examined with this protocol. © RSNA, 2010.

RBE, reference RBE and clinical RBE: applications of these concepts in hadron therapy.

PubMed

Wambersie, A

1999-06-01

Introduction of heavy particles (hadrons) into radiation therapy aims at improving the physical selectivity of the irradiation (e.g. proton beams), or the radiobiological differential effect (e.g. fast neutrons), or both (e.g. heavy-ion beams). Each of these new therapy modalities requires several types of information before prescribing safely the doses to patients, as well as for recording and reporting the treatments: (i) absorbed dose measured in a homogeneous phantom in reference conditions; (ii) dose distribution computed at the level of the target volume(s) and the normal tissues at risk; (iii) radiation quality from which a RBE evaluation could be predicted and (iv) RBE measured on biological systems or derived from clinical observation. In hadron therapy, the RBE of the different beams raises specific problems. For fast neutrons, the RBE varies within wide limits (about 2 to 5) depending on the neutron energy spectrum, dose, and biological system. For protons, the RBE values range between smaller limits (about 1.0 to 1.2). A clinical benefit can thus not be expected from RBE differences. However, the proton RBE problem cannot be ignored since dose differences of about 5% can be detected clinically in some cases. The situation is most complex with heavy ions since RBE variations are at least as large as for fast neutrons, as a function of particle type and energy, dose and biological system. In addition, RBE varies with depth. Radiation quality thus has to be taken into account when prescribing and reporting a treatment. This can be done in different ways: (a) description of the method of beam production; (b) computed LET spectra and/or measured microdosimetric spectra at the points clinically relevant; (c) RBE determination. The most relevant RBE data are those obtained for late tolerance of normal tissues at 2 Gy per fraction ("reference RBE"). The "clinical RBE" selected by the radiation oncologist when prescribing the treatment will be close to the reference RBE, but other factors (such as heterogeneity in dose distribution) may influence the selection of the clinical RBE. Combination of microdosimetric data and experimental RBE values improves the confidence in both sets of data.

Conversion of ICRP male reference phantom to polygon-surface phantom

NASA Astrophysics Data System (ADS)

Yeom, Yeon Soo; Han, Min Cheol; Kim, Chan Hyeong; Jeong, Jong Hwi

2013-10-01

The International Commission on Radiological Protection (ICRP) reference phantoms, developed based on computed tomography images of human bodies, provide much more realism of human anatomy than the previously used MIRD5 (Medical Internal Radiation Dose) mathematical phantoms. It has been, however, realized that the ICRP reference phantoms have some critical limitations showing a considerable amount of holes for the skin and wall organs mainly due to the nature of voxels of which the phantoms are made, especially due to their low voxel resolutions. To address this problem, we are planning to develop the polygon-surface version of ICRP reference phantoms by directly converting the ICRP reference phantoms (voxel phantoms) to polygon-surface phantoms. The objective of this preliminary study is to see if it is indeed possible to construct the high-quality polygon-surface phantoms based on the ICRP reference phantoms maintaining identical organ morphology and also to identify any potential issues, and technologies to address these issues, in advance. For this purpose, in the present study, the ICRP reference male phantom was roughly converted to a polygon-surface phantom. Then, the constructed phantom was implemented in Geant4, Monte Carlo particle transport code, for dose calculations, and the calculated dose values were compared with those of the original ICRP reference phantom to see how much the calculated dose values are sensitive to the accuracy of the conversion process. The results of the present study show that it is certainly possible to convert the ICRP reference phantoms to surface phantoms with enough accuracy. In spite of using relatively less resources (<2 man-months), we were able to construct the polygon-surface phantom with the organ masses perfectly matching the ICRP reference values. The analysis of the calculated dose values also implies that the dose values are indeed not very sensitive to the detailed morphology of the organ models in the phantom for highly penetrating radiations such as photons and neutrons. The results of the electron beams, on the other hand, show that the dose values of the polygon-surface phantom are higher by a factor of 2-5 times than those of the ICRP reference phantom for the skin and wall organs which have large holes due to low voxel resolution. The results demonstrate that the ICRP reference phantom could provide significantly unreasonable dose values to thin or wall organs especially for weakly penetrating radiations. Therefore, when compared to the original ICRP reference phantoms, it is believed that the polygon-surface version of ICRP reference phantoms properly developed will not only provide the same or similar dose values (say, difference <5 or 10%) for highly penetrating radiations, but also provide correct dose values for the weakly penetrating radiations such as electrons and other charged particles.

The Australian radiation protection and nuclear safety agency megavoltage photon thermoluminescence dosimetry postal audit service 2007-2010.

PubMed

Oliver, C P; Butler, D J; Webb, D V

2012-03-01

The Australian radiation protection and nuclear safety agency (ARPANSA) has continuously provided a level 1 mailed thermoluminescence dosimetry audit service for megavoltage photons since 2007. The purpose of the audit is to provide an independent verification of the reference dose output of a radiotherapy linear accelerator in a clinical environment. Photon beam quality measurements can also be made as part of the audit in addition to the output measurements. The results of all audits performed between 2007 and 2010 are presented. The average of all reference beam output measurements calculated as a clinically stated dose divided by an ARPANSA measured dose is 0.9993. The results of all beam quality measurements calculated as a clinically stated quality divided by an ARPANSA measured quality is 1.0087. Since 2011 the provision of all auditing services has been transferred from the Ionizing Radiation Standards section to the Australian Clinical Dosimetry Service (ACDS) which is currently housed within ARPANSA.

Reference Dose for Methylmercury (External Review Draft)

EPA Science Inventory

In 1997, U.S. EPA issued the Mercury Study Report to Congress (MSRC). Among the assessments in the MSRC was a state-of-the-science evaluation of the health effects of methylmercury. There has been considerable discussion within the scientific community regarding the level of e...

Assessment of impact of urbanisation on background radiation exposure and human health risk estimation in Kuala Lumpur, Malaysia.

PubMed

Sanusi, M S M; Ramli, A T; Hassan, W M S W; Lee, M H; Izham, A; Said, M N; Wagiran, H; Heryanshah, A

2017-07-01

Kuala Lumpur has been undergoing rapid urbanisation process, mainly in infrastructure development. The opening of new township and residential in former tin mining areas, particularly in the heavy mineral- or tin-bearing alluvial soil in Kuala Lumpur, is a contentious subject in land-use regulation. Construction practices, i.e. reclamation and dredging in these areas are potential to enhance the radioactivity levels of soil and subsequently, increase the existing background gamma radiation levels. This situation is worsened with the utilisation of tin tailings as construction materials apart from unavoidable soil pollutions due to naturally occurring radioactive materials in construction materials, e.g. granitic aggregate, cement and red clay brick. This study was conducted to assess the urbanisation impacts on background gamma radiation in Kuala Lumpur. The study found that the mean value of measured dose rate was 251±6nGyh -1 (156-392nGyh -1 ) and 4 times higher than the world average value. High radioactivity levels of 238 U (95±12Bqkg -1 ), 232 Th (191±23Bqkg -1 ,) and 40 K (727±130Bqkg -1 ) in soil were identified as the major source of high radiation exposure. Based on statistical ANOVA, t-test, and analyses of cumulative probability distribution, this study has statistically verified the dose enhancements in the background radiation. The effective dose was estimated to be 0.31±0.01mSvy -1 per man. The recommended ICRP reference level (1-20mSvy -1 ) is applicable to the involved existing exposure situation in this study. The estimated effective dose in this study is lower than the ICRP reference level and too low to cause deterministic radiation effects. Nevertheless based on estimations of lifetime radiation exposure risks, this study found that there was small probability for individual in Kuala Lumpur being diagnosed with cancer and dying of cancer. Copyright © 2017 Elsevier Ltd. All rights reserved.

Bioavailability of ambroxol sustained release preparations. Part II: Single and multiple oral dose studies in man.

PubMed

Janssen, T J; Guelen, P J; Vree, T B; Botterblom, M H; Valducci, R

1988-01-01

The bioavailability of a new ambroxol sustained release preparation (75 mg) based on a dialyzing membrane for controlled release was studied in healthy volunteers after single and multiple oral dose in comparison with a standard sustained release formulation in a cross-over study under carefully controlled conditions. Plasma concentrations of ambroxol were measured by means of a HPLC method. Based on AUC data both preparations are found to be bioequivalent, but show different plasma concentration profiles. The test preparation showed a more pronounced sustained release profile than the reference preparation (single dose) resulting in significantly higher steady state plasma levels.

In vivo Investigation of Anti-diabetic Properties of Ripe Onion Juice in Normal and Streptozotocin-induced Diabetic Rats

PubMed Central

Lee, Chul-Won; Lee, Hyung-Seok; Cha, Yong-Jun; Joo, Woo-Hong; Kang, Dae-Ook; Moon, Ja-Young

2013-01-01

The acute and subacute hypoglycemic and antihyperglycemic effects of drinkable ripe onion juice (Commercial product name is “Black Onion Extract”) were investigated in normal and streptozotocin-induced diabetic rats. For tests of acute and subacute hypoglycemic effects, ripe onion juice (5 and 15 mL/kg b.w.) was administered by oral gavage to normal Sprague Dawley rats and measurements of fasting glucose levels and oral glucose tolerance tests were performed. Tolbutamide was used as a reference drug at a single oral dose of 250 mg/kg b.w. To test anti-hyper-glycemic activity, the ripe onion juice was administered to streptozotocin-induced diabetic rats by oral gavage at single dose of 15 mL/kg b.w. per day for 7 consecutive days. Oral administration of the ripe onion juice at either dosed level of 5 or 15 mL/kg b.w. showed no remarkable acute hypoglycemic effect in normal rats. The two dosed levels caused a relatively small reduction, only 18% and 12% (5 and 15 mL/kg b.w., respectively) decrease in glucose levels at 2 h after glucose loading in normal rats. However, at 3 h after glucose loading, blood glucose levels in the ripe onion juice-dosed rats were decreased to the corresponding blood glucose level in tolbutamide-dosed rats. Although showing weak hypoglycemic potential compared to that of tolbutamide, oral administration of ripe onion juice (15 mL/kg b.w.) for a short period (8 days) resulted in a slight reduction in the blood glucose levels that had elevated in Streptozotocin-induced diabetic rats. In conclusion, these results suggest that the commercial product “Black Onion Extract” may possess anti-hyperglycemic potential in diabetes. PMID:24471128

Assessment of dose rate to terrestrial biota in the area around coal fired power plant applying ERICA tool and RESRAD BIOTA code.

PubMed

Ćujić, Mirjana; Dragović, Snežana

2018-08-01

This paper presents the environmental radiation risk assessment based on two software program approaches ERICA Tool (version 1.2) and RESRAD BIOTA (version 1.5) to estimate dose rates to terrestrial biota in the area around the largest coal fired power plant in Serbia. For dose rate assessment software's default reference animals and plants and the best estimated values of activity concentrations of 238 U, 234 U, 234 Th, 232 Th, 230 Th, 226 Ra, 210 Pb, 210 Po, 137 Cs in soil were used. Both approaches revealed the highest contribution to the internal dose rate due to 226 Ra and 210 Po, while 137 Cs contributed the most to the external dose rate. In the investigated area total dose rate to biota derived using ERICA Tool ranged from 0.3 to 14.4 μGy h -1 . The natural radionuclides exhibited significantly higher contribution to the total dose rate than the artificial one. In the investigated area, only dose rate for lichens and bryophytes exceeded ERICA Tool screening value of total dose rate of 10 μGy h -1 suggested as confident that environmental risks are negligible. The assessed total dose rates for reference animals and plants using RESRAD BIOTA were found to be 7 and 3 μGy h -1 , respectively. In RESRAD BIOTA - Level 3, 10 species (Lumbricus terrestris, Rana lessonae, Sciurus vulgaris, Anas platyrhynchos, Lepus europaeus, Vulpes vulpes, Capreolus capreolus, Suss crofa, Quercu srobur, Tilia spp.) representative for the study area were modeled. Among them the highest total dose rate (4.5 μGy h -1 ) was obtained for large mammals. Differences in the predicted dose rates to biota using the two software programs are the consequence of the difference in the values of transfer parameters used to calculate activity concentrations in biota. Doses of ionizing radiation estimated in this study will not exhibit deterministic effects at the population level. Thus, the obtained results indicate no significant radiation impact of coal fired power plant operation on terrestrial biota. This paper confirms the use ERICA Tool and RESRAD BIOTA softwares as flexible and effective means of radiation impact assessment. Copyright © 2017 Elsevier Ltd. All rights reserved.

CERISE, a French radioprotection code, to assess the radiological impact and acceptance criteria of installations for material handling, and recycling or disposal of very low-level radioactive waste

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

Santucci, P.; Guetat, P.

1993-12-31

This document describes the code CERISE, Code d`Evaluations Radiologiques Individuelles pour des Situations en Enterprise et dans l`Environnement. This code has been developed in the frame of European studies to establish acceptance criteria of very low-level radioactive waste and materials. This code is written in Fortran and runs on PC. It calculates doses received by the different pathways: external exposure, ingestion, inhalation and skin contamination. Twenty basic scenarios are already elaborated, which have been determined from previous studies. Calculations establish the relation between surface, specific and/or total activities, and doses. Results can be expressed as doses for an average activitymore » unit, or as average activity limits for a set of reference doses (defined for each scenario analyzed). In this last case, the minimal activity values and the corresponding limiting scenarios, are selected and summarized in a final table.« less

Influence of radiation dose and reconstruction algorithm in MDCT assessment of airway wall thickness: A phantom study

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

Gomez-Cardona, Daniel; Nagle, Scott K.; Department of Radiology, University of Wisconsin-Madison School of Medicine and Public Health, 600 Highland Avenue, Madison, Wisconsin 53792

Purpose: Wall thickness (WT) is an airway feature of great interest for the assessment of morphological changes in the lung parenchyma. Multidetector computed tomography (MDCT) has recently been used to evaluate airway WT, but the potential risk of radiation-induced carcinogenesis—particularly in younger patients—might limit a wider use of this imaging method in clinical practice. The recent commercial implementation of the statistical model-based iterative reconstruction (MBIR) algorithm, instead of the conventional filtered back projection (FBP) algorithm, has enabled considerable radiation dose reduction in many other clinical applications of MDCT. The purpose of this work was to study the impact of radiationmore » dose and MBIR in the MDCT assessment of airway WT. Methods: An airway phantom was scanned using a clinical MDCT system (Discovery CT750 HD, GE Healthcare) at 4 kV levels and 5 mAs levels. Both FBP and a commercial implementation of MBIR (Veo{sup TM}, GE Healthcare) were used to reconstruct CT images of the airways. For each kV–mAs combination and each reconstruction algorithm, the contrast-to-noise ratio (CNR) of the airways was measured, and the WT of each airway was measured and compared with the nominal value; the relative bias and the angular standard deviation in the measured WT were calculated. For each airway and reconstruction algorithm, the overall performance of WT quantification across all of the 20 kV–mAs combinations was quantified by the sum of squares (SSQs) of the difference between the measured and nominal WT values. Finally, the particular kV–mAs combination and reconstruction algorithm that minimized radiation dose while still achieving a reference WT quantification accuracy level was chosen as the optimal acquisition and reconstruction settings. Results: The wall thicknesses of seven airways of different sizes were analyzed in the study. Compared with FBP, MBIR improved the CNR of the airways, particularly at low radiation dose levels. For FBP, the relative bias and the angular standard deviation of the measured WT increased steeply with decreasing radiation dose. Except for the smallest airway, MBIR enabled significant reduction in both the relative bias and angular standard deviation of the WT, particularly at low radiation dose levels; the SSQ was reduced by 50%–96% by using MBIR. The optimal reconstruction algorithm was found to be MBIR for the seven airways being assessed, and the combined use of MBIR and optimal kV–mAs selection resulted in a radiation dose reduction of 37%–83% compared with a reference scan protocol with a dose level of 1 mGy. Conclusions: The quantification accuracy of airway WT is strongly influenced by radiation dose and reconstruction algorithm. The MBIR algorithm potentially allows the desired WT quantification accuracy to be achieved with reduced radiation dose, which may enable a wider clinical use of MDCT for the assessment of airway WT, particularly for younger patients who may be more sensitive to exposures with ionizing radiation.« less

[Effects of berberine on mRNA expression levels of PPARγ and adipocytokines in insulin-resistant adipocytes].

PubMed

Tu, Jun; Luo, Xin-Xin; Li, Bing-Tao; Li, Yu; Xu, Guo-Liang

2016-06-01

Adipocytokines are closely associated with insulin resistance (IR) in adipose tissues, and they are more and more seriously taken in the study of the development of diabetes. This experiment was mainly to study the effect of berberine on mRNA expression levels of PPARγ and adipocytokines in insulin resistant adipocytes, and investigate the molecular mechanism of berberine in enhancing insulin sensitization and application advantages of droplet digital PCR (ddPCR). ddPCR absolute quantification analysis was taken in this experiment to simply and intuitively determine the appropriate reference genes. ddPCR and quantitative Real-time PCR (qPCR) were used to compare the effect of different doses of berberine (10, 20, 50, 100 μmol•L⁻¹) on mRNA expression levels of PPARγ, adiponectin, resistin and leptin in IR 3T3-L1adipocytes. Antagonist GW9662 was added to study the inherent correlation between PPARγ and adiponectin mRNA expression levels. ddPCR results showed that the expression level of β-actin in adipocytes was stable, and suitable as reference gene for normalization of quantitative PCR data. Both of ddPCR and qPCR results showed that, as compared with IR models, the mRNA expression levels of adiponectin were decreased in the treatment with berberine (10, 20, 50, 100 μmol•L⁻¹) in a dose-dependent manner (P<0.01); the expression of PPARγ was decreased by 20, 50, 100 μmol•L⁻¹ berberine in a dose-dependent manner in qPCR assay (P<0.01) and decreased only by 50 and 100 μmol•L⁻¹ berberine in ddPCR assay (P<0.05). PPARγ specific antagonist GW9662 intervention experiment showed that adiponectin gene expression was directly relevant with PPARγ (P<0.05). ddPCR probe assay showed that various doses of berberine could significantly reduce mRNA expression levels of resistin and leptin (P<0.01) in a dose-dependent manner. In conclusion, berberine enhanced insulin sensitization effect not by up-regulating adiponect in expression of transcriptional level in PPARγ-dependent manner, but may by the elevated multimerization of adiponectin in the posttranslational regulation level. Berberine down-regulated the resistin and leptin expression levels, which could alleviate lipolysis and improve IR in adipocytes. ddPCR provided better sensitivity and linear range than qPCR, with obvious technical advantages for the detection of low abundance expression of target genes. Copyright© by the Chinese Pharmaceutical Association.

Designing drug regimens for special intensive care unit populations

PubMed Central

Erstad, Brian L

2015-01-01

This review is intended to help clinicians design drug regimens for special populations of critically ill patients with extremes of body size, habitus and composition that make drug choice or dosing particularly challenging due to the lack of high-level evidence on which to make well-informed clinical decisions. The data sources included a literature search of MEDLINE and EMBASE with reviews of reference lists of retrieved articles. Abstracts of original research investigations and review papers were reviewed for their relevance to drug choice or dosing in the following special critically ill populations: patients with more severe forms of bodyweight or height, patients with amputations or missing limbs, pregnant patients, and patients undergoing extracorporeal membrane oxygenation or plasma exchange. Relevant papers were retrieved and evaluated, and their associated reference lists were reviewed for citations that may have been missed through the electronic search strategy. Relevant original research investigations and review papers that could be used to formulate general principles for drug choice or dosing in special populations of critically ill patients were extracted. Randomized studies with clinically relevant endpoints were not available for performing quantitative analyses. Critically ill patients with changes in body size, habitus and composition require special consideration when designing medication regimens, but there is a paucity of literature on which to make drug-specific, high-level evidence-based recommendations. Based on the evidence that is available, general recommendations are provided for drug choice or dosing in special critically ill populations. PMID:25938029

Evaluation of six TPS algorithms in computing entrance and exit doses.

PubMed

Tan, Yun I; Metwaly, Mohamed; Glegg, Martin; Baggarley, Shaun; Elliott, Alex

2014-05-08

Entrance and exit doses are commonly measured in in vivo dosimetry for comparison with expected values, usually generated by the treatment planning system (TPS), to verify accuracy of treatment delivery. This report aims to evaluate the accuracy of six TPS algorithms in computing entrance and exit doses for a 6 MV beam. The algorithms tested were: pencil beam convolution (Eclipse PBC), analytical anisotropic algorithm (Eclipse AAA), AcurosXB (Eclipse AXB), FFT convolution (XiO Convolution), multigrid superposition (XiO Superposition), and Monte Carlo photon (Monaco MC). Measurements with ionization chamber (IC) and diode detector in water phantoms were used as a reference. Comparisons were done in terms of central axis point dose, 1D relative profiles, and 2D absolute gamma analysis. Entrance doses computed by all TPS algorithms agreed to within 2% of the measured values. Exit doses computed by XiO Convolution, XiO Superposition, Eclipse AXB, and Monaco MC agreed with the IC measured doses to within 2%-3%. Meanwhile, Eclipse PBC and Eclipse AAA computed exit doses were higher than the IC measured doses by up to 5.3% and 4.8%, respectively. Both algorithms assume that full backscatter exists even at the exit level, leading to an overestimation of exit doses. Despite good agreements at the central axis for Eclipse AXB and Monaco MC, 1D relative comparisons showed profiles mismatched at depths beyond 11.5 cm. Overall, the 2D absolute gamma (3%/3 mm) pass rates were better for Monaco MC, while Eclipse AXB failed mostly at the outer 20% of the field area. The findings of this study serve as a useful baseline for the implementation of entrance and exit in vivo dosimetry in clinical departments utilizing any of these six common TPS algorithms for reference comparison.

TU-EF-304-09: Quantifying the Biological Effects of Therapeutic Protons by LET Spectrum Analysis

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

Guan, F; Bronk, L; Kerr, M

2015-06-15

Purpose: To correlate in vitro cell kill with linear energy transfer (LET) spectra using Monte Carlo simulations and knowledge obtained from previous high-throughput in vitro proton relative biological effectiveness (RBE) measurements. Methods: The Monte Carlo simulation toolkit Geant4 was used to design the experimental setups and perform the dose, dose-averaged LET, and LET spectra calculations. The clonogenic assay was performed using the H460 lung cancer cell line in standard 6-well plates. Using two different experimental setups, the same dose and dose-averaged LET (12.6 keV/µm) was delivered to the cell layer; however, each respective energy or LET spectrum was different. Wemore » quantified the dose contributions from high-LET (≥10 keV/µm, threshold determined by previous RBE measurements) events in the LET spectra separately for these two setups as 39% and 53%. 8 dose levels with 1 Gy increments were delivered. The photon reference irradiation was performed using 6 MV x-rays from a LINAC. Results: The survival curves showed that both proton irradiations demonstrated an increased RBE compared to the reference photon irradiation. Within the proton-irradiated cells, the setup with 53% dose contribution from high-LET events exhibited the higher biological effectiveness. Conclusion: The experimental results indicate that the dose-averaged LET may not be an appropriate indicator to quantify the biological effects of protons when the LET spectrum is broad enough to contain both low- and high-LET events. Incorporating the LET spectrum distribution into robust intensity-modulated proton therapy optimization planning may provide more accurate biological dose distribution than using the dose-averaged LET. NIH Program Project Grant 2U19CA021239-35.« less

MO-FG-CAMPUS-IeP1-03: Establishment of Provincial Diagnostic Reference Levels in Pediatric Imaging

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

Tonkopi, E; Queen Elizabeth II Health Sciences Ctr; O’Brien, K

Purpose: To establish provincial diagnostic reference levels (DRLs) in pediatric general radiography and computed tomography (CT) as a tool for the optimization of exposure parameters. Methods: Patient dose survey was conducted in the only pediatric hospital in the province of Nova Scotia. The DRLs were established as the 75th percentile of patient dose distributions in different age groups. For routine radiography projections the DRLs were determined in terms of entrance surface dose (ESD) calculated from the radiation output measurements and the tube current-exposure time product (mAs) recorded for each examination. Patient thickness was measured by the technologist during the examination.more » The CR and DR systems, employing respectively a fixed technique and phototiming, were evaluated separately; a two-tailed Student’s t-test was used to determine the significance of differences between the means of dose distributions. The CT studies included routine head, chest, abdomen/pelvis, and chest/abdomen/pelvis. The volume CT dose index (CTDIvol) and dose-length product (DLP) values were extracted retrospectively from PACS. The correction factors based on the effective diameter of the patient were applied to the CT dosimetry metrics based on the standard phantoms. Results: The provincial DRLs were established in the following age groups: newborn, 1, 5, 10, and 15 year olds. In general radiography the DR systems demonstrated slightly lower dose than the CR for all views, however the differences were not statistically significant (p > 0.05) for all examinations. In CT the provincial DRLs were lower than the published data, except for head DLPs in all age categories. This might be due to the small patient sample size in the survey. Future work will include additional CT data collection over an extended period of time. Conclusion: Provincial DRLs were established in the dedicated children’s hospital to provide guidance for the other facilities in examinations of pediatric patients.« less

Measuring drug absorption improves interpretation of behavioral responses in a larval zebrafish locomotor assay for predicting seizure liability.

PubMed

Cassar, Steven; Breidenbach, Laura; Olson, Amanda; Huang, Xin; Britton, Heather; Woody, Clarissa; Sancheti, Pankajkumar; Stolarik, DeAnne; Wicke, Karsten; Hempel, Katja; LeRoy, Bruce

2017-11-01

Unanticipated effects on the central nervous system are a concern during new drug development. A larval zebrafish locomotor assay can reveal seizure liability of experimental molecules before testing in mammals. Relative absorption of compounds by larvae is lacking in prior reports of such assays; having those data may be valuable for interpreting seizure liability assay performance. Twenty-eight reference drugs were tested at multiple dose levels in fish water and analyzed by a blinded investigator. Responses of larval zebrafish were quantified during a 30min dosing period. Predictive metrics were calculated by comparing fish activity to mammalian seizure liability for each drug. Drug level analysis was performed to calculate concentrations in dose solutions and larvae. Fifteen drug candidates with neuronal targets, some having preclinical convulsion findings in mammals, were tested similarly. The assay has good predictive value of established mammalian responses for reference drugs. Analysis of drug absorption by larval fish revealed a positive correlation between hyperactive behavior and pro-convulsive drug absorption. False negative results were associated with significantly lower compound absorption compared to true negative, or true positive results. The predictive value for preclinical toxicology findings was inferior to that suggested by reference drugs. Disproportionately low exposures in larvae giving false negative results demonstrate that drug exposure analysis can help interpret results. Due to the rigorous testing commonly performed in preclinical toxicology, predicting convulsions in those studies may be more difficult than predicting effects from marketed drugs. Copyright © 2017 Elsevier Inc. All rights reserved.

Methods for CT automatic exposure control protocol translation between scanner platforms.

PubMed

McKenney, Sarah E; Seibert, J Anthony; Lamba, Ramit; Boone, John M

2014-03-01

An imaging facility with a diverse fleet of CT scanners faces considerable challenges when propagating CT protocols with consistent image quality and patient dose across scanner makes and models. Although some protocol parameters can comfortably remain constant among scanners (eg, tube voltage, gantry rotation time), the automatic exposure control (AEC) parameter, which selects the overall mA level during tube current modulation, is difficult to match among scanners, especially from different CT manufacturers. Objective methods for converting tube current modulation protocols among CT scanners were developed. Three CT scanners were investigated, a GE LightSpeed 16 scanner, a GE VCT scanner, and a Siemens Definition AS+ scanner. Translation of the AEC parameters such as noise index and quality reference mAs across CT scanners was specifically investigated. A variable-diameter poly(methyl methacrylate) phantom was imaged on the 3 scanners using a range of AEC parameters for each scanner. The phantom consisted of 5 cylindrical sections with diameters of 13, 16, 20, 25, and 32 cm. The protocol translation scheme was based on matching either the volumetric CT dose index or image noise (in Hounsfield units) between two different CT scanners. A series of analytic fit functions, corresponding to different patient sizes (phantom diameters), were developed from the measured CT data. These functions relate the AEC metric of the reference scanner, the GE LightSpeed 16 in this case, to the AEC metric of a secondary scanner. When translating protocols between different models of CT scanners (from the GE LightSpeed 16 reference scanner to the GE VCT system), the translation functions were linear. However, a power-law function was necessary to convert the AEC functions of the GE LightSpeed 16 reference scanner to the Siemens Definition AS+ secondary scanner, because of differences in the AEC functionality designed by these two companies. Protocol translation on the basis of quantitative metrics (volumetric CT dose index or measured image noise) is feasible. Protocol translation has a dependency on patient size, especially between the GE and Siemens systems. Translation schemes that preserve dose levels may not produce identical image quality. Copyright © 2014 American College of Radiology. Published by Elsevier Inc. All rights reserved.

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

Hubbard, L; Ziemer, B; Lipinski, J

Purpose: To evaluate the accuracy of a low-dose, first-pass-analysis (FPA) dynamic computed tomography angiography and perfusion (CTAP) technique, for whole-organ anatomical and functional assessment of coronary artery disease (CAD). Methods: An angioplasty balloon was advanced into the left anterior descending (LAD) coronary artery of five swine (35–45 kg) to induce several levels of stenosis at maximal hyperemia (intracoronary adenosine, 240 µg/min). Reference fluorescence microspheres and intravenous contrast (370 mg/mL iodine, 25 mL, 7 mL/s) were injected centrally and dynamic imaging was performed using a 320-slice CT scanner at 100 kVp and 200 mA. Twenty volume scans were acquired per stenosismore » level to capture complete aortic and myocardial enhancement curves, but only two volume scans were used for whole-organ dynamic FPA CTAP measurement. All CTAP measurements in the LAD were compared to the reference microsphere perfusion measurements using linear regression, concordance correlation, and Bland-Altman analysis. Results: The result of dynamic FPA CTAP measurement in the LAD was in good agreement with the reference microsphere perfusion measurement (P-CTAP = 1.01 P-MICRO + 0.16, R{sup 2} = 0.95). The root mean square error (RMSE) and difference (RMSD) of measurement were 0.51 mL/min/g and 0.47 mL/min/g, respectively. Bland-Altman analysis demonstrated negligible systematic measurement bias. Additionally, the concordance correlation coefficient (CCC) was found to be ρ = 0.97, indicating excellent agreement between dynamic FPA CTAP measurement and the reference microsphere perfusion measurement. Lastly, the effective dose of the proposed technique using the “simulated” two-volume scan CTAP acquisition protocol was 2.6 mSv; much lower than the ∼10 mSv effective dose of current dynamic CTP techniques alone. Conclusion: The results indicate the potential for significant improvements in CAD assessment through low-dose, quantitative dynamic FPA CTAP. Such improvements are afforded through whole-organ CT scanning technology, and have the potential to improve patient outcomes and lead to healthier patient lives. Conflict of Interest (only if applicable): Grant funding from Toshiba America Medical Systems.« less

Radiation protection recommendations as applied to the disposal of long-lived solid radioactive waste. A report of The International Commission on Radiological Protection.

PubMed

1998-01-01

(79) Waste, by definition, has no benefit. It should be viewed as one aspect of the beneficial practice that gave rise to it. Furthermore, radioactive waste management should be placed in the context of the management of society's waste in general. (80) A major issue in evaluating the acceptability of a disposal system for long-lived solid radioactive waste is that doses or risks may arise from exposures in the distant future. There is uncertainty surrounding any estimate of these doses or risks due to lack of knowledge about future conditions. Such exposures are treated as potential exposures as their magnitude depends on future processes and conditions that have probabilities associated with them. (81) Nevertheless, the Commission recognises a basic principle that individuals and populations in the future should be afforded at least the same level of protection from the action of disposing of radioactive waste today as is the current generation. This implies use of the current quantitative dose and risk criteria derived from considering associated health detriment. Therefore, protection of future generations should be achieved by applying these dose or risk criteria to the estimated future doses or risks in appropriately defined critical groups. These estimates should not be regarded as measures of health detriment beyond times of around several hundreds of years into the future. In the case of these longer time periods, they represent indicators of the protection afforded by the disposal system. (82 Constrained optimisation is the central approach to evaluating the radiological acceptability of a waste disposal system; dose or risk constraints are used rather than dose or risk limits. By this transition from limitation to optimisation, the needs of practical application of the radiological protection system to the disposal of long-lived solid waste disposal are met: determination of acceptability now for exposures that may occur in the distant future. Optimisation should be applied in an iterative manner during the disposal system development process and should particularly cover both site selection and repository design. (83) Two broad categories of exposure situations should be considered: natural processes and human intrusion. The latter only refers to intrusion that is inadvertent. The radiological implications of deliberate intrusion into a repository are the responsibility of the intruder. Assessed doses or risks arising from natural processes should be compared with a dose constraint of 0.3 mSv per year or its risk equivalent of around 10(-5) per year. With regard to human intrusion, the consequences from one or more plausible stylized scenarios should be considered in order to evaluate the resilience of the repository to such events. (84) The Commission considers that in circumstances where human intrusion could lead to doses to those living around the site sufficiently high that intervention on current criteria would almost always be justified, reasonable efforts should be made at the repository development stage to reduce the probability of human intrusion or to limit its consequences. In this respect, the Commission has previously advised that an existing annual dose of around 10 mSv per year may be used as a generic reference level below which intervention is not likely to be justifiable. Conversely, an existing annual dose of around 100 mSv per year may be used as a generic reference level above which intervention should be considered almost always justifiable. Similar considerations apply in situations where the thresholds for deterministic effects in relevant organs are exceeded. (85) Compliance with the constraints can be assessed by utilising either an aggregated risk-oriented approach, with a risk constraint, or a disaggregated dose/probability approach, with a dose constraint, or a combination of both. A similar level of protection can be achieved by any of these approaches; however, more information may

Comparison of internal dose estimates obtained using organ-level, voxel S value, and Monte Carlo techniques

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

Grimes, Joshua, E-mail: grimes.joshua@mayo.edu; Celler, Anna

2014-09-15

Purpose: The authors’ objective was to compare internal dose estimates obtained using the Organ Level Dose Assessment with Exponential Modeling (OLINDA/EXM) software, the voxel S value technique, and Monte Carlo simulation. Monte Carlo dose estimates were used as the reference standard to assess the impact of patient-specific anatomy on the final dose estimate. Methods: Six patients injected with{sup 99m}Tc-hydrazinonicotinamide-Tyr{sup 3}-octreotide were included in this study. A hybrid planar/SPECT imaging protocol was used to estimate {sup 99m}Tc time-integrated activity coefficients (TIACs) for kidneys, liver, spleen, and tumors. Additionally, TIACs were predicted for {sup 131}I, {sup 177}Lu, and {sup 90}Y assuming themore » same biological half-lives as the {sup 99m}Tc labeled tracer. The TIACs were used as input for OLINDA/EXM for organ-level dose calculation and voxel level dosimetry was performed using the voxel S value method and Monte Carlo simulation. Dose estimates for {sup 99m}Tc, {sup 131}I, {sup 177}Lu, and {sup 90}Y distributions were evaluated by comparing (i) organ-level S values corresponding to each method, (ii) total tumor and organ doses, (iii) differences in right and left kidney doses, and (iv) voxelized dose distributions calculated by Monte Carlo and the voxel S value technique. Results: The S values for all investigated radionuclides used by OLINDA/EXM and the corresponding patient-specific S values calculated by Monte Carlo agreed within 2.3% on average for self-irradiation, and differed by as much as 105% for cross-organ irradiation. Total organ doses calculated by OLINDA/EXM and the voxel S value technique agreed with Monte Carlo results within approximately ±7%. Differences between right and left kidney doses determined by Monte Carlo were as high as 73%. Comparison of the Monte Carlo and voxel S value dose distributions showed that each method produced similar dose volume histograms with a minimum dose covering 90% of the volume (D90) agreeing within ±3%, on average. Conclusions: Several aspects of OLINDA/EXM dose calculation were compared with patient-specific dose estimates obtained using Monte Carlo. Differences in patient anatomy led to large differences in cross-organ doses. However, total organ doses were still in good agreement since most of the deposited dose is due to self-irradiation. Comparison of voxelized doses calculated by Monte Carlo and the voxel S value technique showed that the 3D dose distributions produced by the respective methods are nearly identical.« less

Computational assessment of effective dose and patient specific doses for kilovoltage stereotactic radiosurgery of wet age-related macular degeneration

NASA Astrophysics Data System (ADS)

Hanlon, Justin Mitchell

Age-related macular degeneration (AMD) is a leading cause of vision loss and a major health problem for people over the age of 50 in industrialized nations. The current standard of care, ranibizumab, is used to help slow and in some cases stabilize the process of AMD, but requires frequent invasive injections into the eye. Interest continues for stereotactic radiosurgery (SRS), an option that provides a non-invasive treatment for the wet form of AMD, through the development of the IRay(TM) (Oraya Therapeutics, Inc., Newark, CA). The goal of this modality is to destroy choroidal neovascularization beneath the pigment epithelium via delivery of three 100 kVp photon beams entering through the sclera and overlapping on the macula delivering up to 24 Gy of therapeutic dose over a span of approximately 5 minutes. The divergent x-ray beams targeting the fovea are robotically positioned and the eye is gently immobilized by a suction-enabled contact lens. Device development requires assessment of patient effective dose, reference patient mean absorbed doses to radiosensitive tissues, and patient specific doses to the lens and optic nerve. A series of head phantoms, including both reference and patient specific, was derived from CT data and employed in conjunction with the MCNPX 2.5.0 radiation transport code to simulate treatment and evaluate absorbed doses to potential tissues-at-risk. The reference phantoms were used to evaluate effective dose and mean absorbed doses to several radiosensitive tissues. The optic nerve was modeled with changeable positions based on individual patient variability seen in a review of head CT scans gathered. Patient specific phantoms were used to determine the effect of varying anatomy and gaze. The results showed that absorbed doses to the non-targeted tissues were below the threshold levels for serious complications; specifically the development of radiogenic cataracts and radiation induced optic neuropathy (RON). The effective dose determined (0.29 mSv) is comparable to diagnostic procedures involving the head, such as an x-ray or CT scan. Thus, the computational assessment performed indicates that a previously established therapeutic dose can be delivered effectively to the macula with IRay(TM) without the potential for secondary complications.

Quantitative Image Quality and Histogram-Based Evaluations of an Iterative Reconstruction Algorithm at Low-to-Ultralow Radiation Dose Levels: A Phantom Study in Chest CT

PubMed Central

Lee, Ki Baek

2018-01-01

Objective To describe the quantitative image quality and histogram-based evaluation of an iterative reconstruction (IR) algorithm in chest computed tomography (CT) scans at low-to-ultralow CT radiation dose levels. Materials and Methods In an adult anthropomorphic phantom, chest CT scans were performed with 128-section dual-source CT at 70, 80, 100, 120, and 140 kVp, and the reference (3.4 mGy in volume CT Dose Index [CTDIvol]), 30%-, 60%-, and 90%-reduced radiation dose levels (2.4, 1.4, and 0.3 mGy). The CT images were reconstructed by using filtered back projection (FBP) algorithms and IR algorithm with strengths 1, 3, and 5. Image noise, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) were statistically compared between different dose levels, tube voltages, and reconstruction algorithms. Moreover, histograms of subtraction images before and after standardization in x- and y-axes were visually compared. Results Compared with FBP images, IR images with strengths 1, 3, and 5 demonstrated image noise reduction up to 49.1%, SNR increase up to 100.7%, and CNR increase up to 67.3%. Noteworthy image quality degradations on IR images including a 184.9% increase in image noise, 63.0% decrease in SNR, and 51.3% decrease in CNR, and were shown between 60% and 90% reduced levels of radiation dose (p < 0.0001). Subtraction histograms between FBP and IR images showed progressively increased dispersion with increased IR strength and increased dose reduction. After standardization, the histograms appeared deviated and ragged between FBP images and IR images with strength 3 or 5, but almost normally-distributed between FBP images and IR images with strength 1. Conclusion The IR algorithm may be used to save radiation doses without substantial image quality degradation in chest CT scanning of the adult anthropomorphic phantom, down to approximately 1.4 mGy in CTDIvol (60% reduced dose). PMID:29354008

Pharmacokinetics and bioequivalence study of a fixed dose combination of rabeprazole and itopride in healthy Indian volunteers.

PubMed

Sahoo, Bijay Kumar; Das, Ayan; Agarwal, Sangita; Bhaumik, Uttam; Bose, Anirbandeep; Ghosh, Debotri; Roy, Bikash; Pal, Tapan Kumar

2009-01-01

The aim of the present study was to compare the pharmacokinetics of rabeprazole (CAS 117976-89-3) and itopride (CAS 122898-67-3) after oral administration of a rabeprazole (20 mg)-itopride (150 mg) fixed dose combination (FDC) in healthy human volunteers. The bioequivalence of two formulations (test and reference) was determined in 12 healthy Indian male volunteers (age: 25.25 +/- 4.69 years; weight: 60.50 +/- 5.04 kg) in a randomized, single-dose, two-period, two-treatment crossover study. Both formulations were administered orally as a single dose, with the treatments separated by a washout period of 1 week. Rabeprazole and itopride plasma levels were determined by a validated HPLC method using UV detection. The formulations were compared using the pharmacokinetic parameters area under the plasma concentration-time curve (AUC(0-t)), area under the plasma concentration-time curve from zero to infinity (AUC(0-infinity)) and peak plasma concentration (Cmax). General linear model (GLM) procedures were used in which sources of variation were subject, treatment and period. The results indicated that there were no statistically significant differences (P > 0.05) between the logarithmically transformed AUC(0-infinity) and Cmax values between test and reference formulation. The 90% confidence interval for the ratio of the logarithmically transformed AUC(0-t), AUC(0-infinity) and Cmax were within the bioequivalence limits of 0.8-1.25 and the relative bioavailability of rabeprazole and itopride test and reference formulations was 98.24 and 93.65%, respectively.

Patient doses from fluoroscopically guided cardiac procedures in pediatrics

NASA Astrophysics Data System (ADS)

Martinez, L. C.; Vano, E.; Gutierrez, F.; Rodriguez, C.; Gilarranz, R.; Manzanas, M. J.

2007-08-01

Infants and children are a higher risk population for radiation cancer induction compared to adults. Although some values on pediatric patient doses for cardiac procedures have been reported, data to determine reference levels are scarce, especially when compared to those available for adults in diagnostic and therapeutic procedures. The aim of this study is to make a new contribution to the scarce published data in pediatric cardiac procedures and help in the determination of future dose reference levels. This paper presents a set of patient dose values, in terms of air kerma area product (KAP) and entrance surface air kerma (ESAK), measured in a pediatric cardiac catheterization laboratory equipped with a biplane x-ray system with dynamic flat panel detectors. Cardiologists were properly trained in radiation protection. The study includes 137 patients aged between 10 days and 16 years who underwent diagnostic catheterizations or therapeutic procedures. Demographic data and technical details of the procedures were also gathered. The x-ray system was submitted to a quality control programme, including the calibration of the transmission ionization chamber. The age distribution of the patients was 47 for <1 year; 52 for 1-<5 years; 25 for 5-<10 years and 13 for 10-<16 years. Median values of KAP were 1.9, 2.9, 4.5 and 15.4 Gy cm2 respectively for the four age bands. These KAP values increase by a factor of 8 when moving through the four age bands. The probability of a fatal cancer per fluoroscopically guided cardiac procedure is about 0.07%. Median values of ESAK for the four age bands were 46, 50, 56 and 163 mGy, which lie far below the threshold for deterministic effects on the skin. These dose values are lower than those published in previous papers.

Corrective Action Investigation Plan for Corrective Action Unit 569: Area 3 Yucca Flat Atmospheric Test Sites Nevada National Security Site, Nevada, Revision 0

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

Patrick Matthews; Christy Sloop

2012-02-01

Corrective Action Unit (CAU) 569 is located in Area 3 of the Nevada National Security Site, which is approximately 65 miles northwest of Las Vegas, Nevada. Corrective Action Unit 569 comprises the nine numbered corrective action sites (CASs) and one newly identified site listed below: (1) 03-23-09, T-3 Contamination Area (hereafter referred to as Annie, Franklin, George, and Moth); (2) 03-23-10, T-3A Contamination Area (hereafter referred to as Harry and Hornet); (3) 03-23-11, T-3B Contamination Area (hereafter referred to as Fizeau); (4) 03-23-12, T-3S Contamination Area (hereafter referred to as Rio Arriba); (5) 03-23-13, T-3T Contamination Area (hereafter referred tomore » as Catron); (6) 03-23-14, T-3V Contamination Area (hereafter referred to as Humboldt); (7) 03-23-15, S-3G Contamination Area (hereafter referred to as Coulomb-B); (8) 03-23-16, S-3H Contamination Area (hereafter referred to as Coulomb-A); (9) 03-23-21, Pike Contamination Area (hereafter referred to as Pike); and (10) Waste Consolidation Site 3A. Because CAU 569 is a complicated site containing many types of releases, it was agreed during the data quality objectives (DQO) process that these sites will be grouped. These sites are being investigated because existing information on the nature and extent of potential contamination is insufficient to evaluate and recommend corrective action alternatives (CAAs). Additional information will be obtained by conducting a corrective action investigation before evaluating CAAs and selecting the appropriate corrective action for each study group. The results of the field investigation will support a defensible evaluation of viable CAAs that will be presented in the Corrective Action Decision Document. The sites will be investigated based on the DQOs developed on September 26, 2011, by representatives of the Nevada Division of Environmental Protection and the U.S. Department of Energy (DOE), National Nuclear Security Administration Nevada Site Office. The DQO process was used to identify and define the type, amount, and quality of data needed to develop and evaluate appropriate corrective actions for CAU 569. The presence and nature of contamination at CAU 569 will be evaluated based on information collected from a field investigation. Radiological contamination will be evaluated based on a comparison of the total effective dose (TED) at sample locations to the dose-based final action level (FAL). The TED will be calculated as the total of separate estimates of internal and external dose. Results from the analysis of soil samples will be used to calculate internal radiological dose. Thermoluminescent dosimeters placed at the center of each sample location will be used to measure external radiological dose. A field investigation will be performed to define any areas where TED exceeds the FAL and to determine whether contaminants of concern are present at the site from other potential releases. The presence and nature of contamination from other types of releases (e.g., excavation, migration, and any potential releases discovered during the investigation) will be evaluated using soil samples collected from biased locations indicating the highest levels of contamination. Appendix A provides a detailed discussion of the DQO methodology and the objectives specific to each study group.« less

Fetal and maternal dose assessment for diagnostic scans during pregnancy

NASA Astrophysics Data System (ADS)

Rafat Motavalli, Laleh; Miri Hakimabad, Hashem; Hoseinian Azghadi, Elie

2016-05-01

Despite the concerns about prenatal exposure to ionizing radiation, the number of nuclear medicine examinations performed for pregnant women increased in the past decade. This study attempts to better quantify radiation doses due to diagnostic nuclear medicine procedures during pregnancy with the help of our recently developed 3, 6, and 9 month pregnant hybrid phantoms. The reference pregnant models represent the adult female international commission on radiological protection (ICRP) reference phantom as a base template with a fetus in her gravid uterus. Six diagnostic scintigraphy scans using different radiopharmaceuticals were selected as typical diagnostic nuclear medicine procedures. Furthermore, the biokinetic data of radioiodine was updated in this study. A compartment representing iodide in fetal thyroid was addressed explicitly in the biokinetic model. Calculations were performed using the Monte Carlo transport method. Tabulated dose coefficients for both maternal and fetal organs are provided. The comparison was made with the previously published fetal doses calculated for stylized pregnant female phantoms. In general, the fetal dose in previous studies suffers from an underestimation of up to 100% compared to fetal dose at organ level in this study. A maximum of difference in dose was observed for the fetal thyroid compared to the previous studies, in which the traditional models did not contain the fetal thyroid. Cumulated activities of major source organs are primarily responsible for the discrepancies in the organ doses. The differences in fetal dose depend on several other factors including chord length distribution between fetal organs and maternal major source organs, and anatomical differences according to gestation periods. Finally, considering the results of this study, which was based on the realistic pregnant female phantoms, a more informed evaluation of the risks and benefits of the different procedures could be made.

Direct dose mapping versus energy/mass transfer mapping for 4D dose accumulation: fundamental differences and dosimetric consequences.

PubMed

Li, Haisen S; Zhong, Hualiang; Kim, Jinkoo; Glide-Hurst, Carri; Gulam, Misbah; Nurushev, Teamour S; Chetty, Indrin J

2014-01-06

The direct dose mapping (DDM) and energy/mass transfer (EMT) mapping are two essential algorithms for accumulating the dose from different anatomic phases to the reference phase when there is organ motion or tumor/tissue deformation during the delivery of radiation therapy. DDM is based on interpolation of the dose values from one dose grid to another and thus lacks rigor in defining the dose when there are multiple dose values mapped to one dose voxel in the reference phase due to tissue/tumor deformation. On the other hand, EMT counts the total energy and mass transferred to each voxel in the reference phase and calculates the dose by dividing the energy by mass. Therefore it is based on fundamentally sound physics principles. In this study, we implemented the two algorithms and integrated them within the Eclipse treatment planning system. We then compared the clinical dosimetric difference between the two algorithms for ten lung cancer patients receiving stereotactic radiosurgery treatment, by accumulating the delivered dose to the end-of-exhale (EE) phase. Specifically, the respiratory period was divided into ten phases and the dose to each phase was calculated and mapped to the EE phase and then accumulated. The displacement vector field generated by Demons-based registration of the source and reference images was used to transfer the dose and energy. The DDM and EMT algorithms produced noticeably different cumulative dose in the regions with sharp mass density variations and/or high dose gradients. For the planning target volume (PTV) and internal target volume (ITV) minimum dose, the difference was up to 11% and 4% respectively. This suggests that DDM might not be adequate for obtaining an accurate dose distribution of the cumulative plan, instead, EMT should be considered.

Direct dose mapping versus energy/mass transfer mapping for 4D dose accumulation: fundamental differences and dosimetric consequences

NASA Astrophysics Data System (ADS)

Li, Haisen S.; Zhong, Hualiang; Kim, Jinkoo; Glide-Hurst, Carri; Gulam, Misbah; Nurushev, Teamour S.; Chetty, Indrin J.

2014-01-01

The direct dose mapping (DDM) and energy/mass transfer (EMT) mapping are two essential algorithms for accumulating the dose from different anatomic phases to the reference phase when there is organ motion or tumor/tissue deformation during the delivery of radiation therapy. DDM is based on interpolation of the dose values from one dose grid to another and thus lacks rigor in defining the dose when there are multiple dose values mapped to one dose voxel in the reference phase due to tissue/tumor deformation. On the other hand, EMT counts the total energy and mass transferred to each voxel in the reference phase and calculates the dose by dividing the energy by mass. Therefore it is based on fundamentally sound physics principles. In this study, we implemented the two algorithms and integrated them within the Eclipse treatment planning system. We then compared the clinical dosimetric difference between the two algorithms for ten lung cancer patients receiving stereotactic radiosurgery treatment, by accumulating the delivered dose to the end-of-exhale (EE) phase. Specifically, the respiratory period was divided into ten phases and the dose to each phase was calculated and mapped to the EE phase and then accumulated. The displacement vector field generated by Demons-based registration of the source and reference images was used to transfer the dose and energy. The DDM and EMT algorithms produced noticeably different cumulative dose in the regions with sharp mass density variations and/or high dose gradients. For the planning target volume (PTV) and internal target volume (ITV) minimum dose, the difference was up to 11% and 4% respectively. This suggests that DDM might not be adequate for obtaining an accurate dose distribution of the cumulative plan, instead, EMT should be considered.

Cloud-Based CT Dose Monitoring using the DICOM-Structured Report: Fully Automated Analysis in Regard to National Diagnostic Reference Levels.

PubMed

Boos, J; Meineke, A; Rubbert, C; Heusch, P; Lanzman, R S; Aissa, J; Antoch, G; Kröpil, P

2016-03-01

To implement automated CT dose data monitoring using the DICOM-Structured Report (DICOM-SR) in order to monitor dose-related CT data in regard to national diagnostic reference levels (DRLs). We used a novel in-house co-developed software tool based on the DICOM-SR to automatically monitor dose-related data from CT examinations. The DICOM-SR for each CT examination performed between 09/2011 and 03/2015 was automatically anonymized and sent from the CT scanners to a cloud server. Data was automatically analyzed in accordance with body region, patient age and corresponding DRL for volumetric computed tomography dose index (CTDIvol) and dose length product (DLP). Data of 36,523 examinations (131,527 scan series) performed on three different CT scanners and one PET/CT were analyzed. The overall mean CTDIvol and DLP were 51.3% and 52.8% of the national DRLs, respectively. CTDIvol and DLP reached 43.8% and 43.1% for abdominal CT (n=10,590), 66.6% and 69.6% for cranial CT (n=16,098) and 37.8% and 44.0% for chest CT (n=10,387) of the compared national DRLs, respectively. Overall, the CTDIvol exceeded national DRLs in 1.9% of the examinations, while the DLP exceeded national DRLs in 2.9% of the examinations. Between different CT protocols of the same body region, radiation exposure varied up to 50% of the DRLs. The implemented cloud-based CT dose monitoring based on the DICOM-SR enables automated benchmarking in regard to national DRLs. Overall the local dose exposure from CT reached approximately 50% of these DRLs indicating that DRL actualization as well as protocol-specific DRLs are desirable. The cloud-based approach enables multi-center dose monitoring and offers great potential to further optimize radiation exposure in radiological departments. • The newly developed software based on the DICOM-Structured Report enables large-scale cloud-based CT dose monitoring • The implemented software solution enables automated benchmarking in regard to national DRLs • The local radiation exposure from CT reached approximately 50 % of the national DRLs • The cloud-based approach offers great potential for multi-center dose analysis. © Georg Thieme Verlag KG Stuttgart · New York.

Optimisation of environmental remediation: how to select and use the reference levels.

PubMed

Balonov, M; Chipiga, L; Kiselev, S; Sneve, M; Yankovich, T; Proehl, G

2018-06-01

A number of past industrial activities and accidents have resulted in the radioactive contamination of large areas at many sites around the world, giving rise to a need for remediation. According to the International Commission on Radiological Protection (ICRP) and International Atomic Energy Agency (IAEA), such situations should be managed as existing exposure situations (ExESs). Control of exposure to the public in ExESs is based on the application of appropriate reference levels (RLs) for residual doses. The implementation of this potentially fruitful concept for the optimisation of remediation in various regions is hampered by a lack of practical experience and relevant guidance. This paper suggests a generic methodology for the selection of numeric values of relevant RLs both in terms of residual annual effective dose and derived RLs (DRLs) based on an appropriate dose assessment. The value for an RL should be selected in the range of the annual residual effective dose of 1-20 mSv, depending on the prevailing circumstances for the exposure under consideration. Within this range, RL values should be chosen by the following assessment steps: (a) assessment of the projected dose, i.e. the dose to a representative person without remedial actions by means of a realistic model as opposed to a conservative model; (b) modelling of the residual dose to a representative person following application of feasible remedial actions; and (c) selection of an RL value between the projected and residual doses, taking account of the prevailing social and economic conditions. This paper also contains some recommendations for practical implementation of the selected RLs for the optimisation of public protection. The suggested methodology used for the selection of RLs (in terms of dose) and the calculation of DRLs (in terms of activity concentration in food, ambient dose rate, etc) has been illustrated by a retrospective analysis of post-Chernobyl monitoring and modelling data from the Bryansk region, Russia, 2001. From this example, it follows that analysis of real data leads to the selection of an RL from a relatively narrow annual dose range (in this case, about 2-3 mSv), from which relevant DRLs can be calculated and directly used for optimisation of the remediation programme.

The relationship between total cholinesterase activity and mortality in four butterfly species

USGS Publications Warehouse

Bargar, Timothy A.

2012-01-01

The relationship between total cholinesterase activity (TChE) and mortality in four butterfly species (great southern white [Ascia monuste], common buckeye [Junonia coenia], painted lady [Vanessa cardui], and julia butterflies [Dryas julia]) was investigated. Acute contact toxicity studies were conducted to evaluate the response (median lethal dose [LD50] and TChE) of the four species following exposure to the organophosphate insecticide naled. The LD50 for these butterflies ranged from 2.3 to 7.6 μg/g. The average level of TChE inhibition associated with significant mortality ranged from 26 to 67%, depending on the species. The lower bounds of normal TChE activity (2 standard deviations less than the average TChE for reference butterflies) ranged from 8.4 to 12.3 μM/min/g. As a percentage of the average reference TChE activity for the respective species, the lower bounds were similar to the inhibition levels associated with significant mortality, indicating there was little difference between the dose resulting in significant TChE inhibition and that resulting in mortality.

Development of action levels for MED/MPD skin-testing units in ultraviolet phototherapy

NASA Astrophysics Data System (ADS)

O'Connor, Una M.; O'Hare, Neil J.

2003-03-01

Ultraviolet (UV) Phototherapy is commonly used for treatment of skin diseases such as psoriasis and eczema. Treatment is carried out using UV phototherapy units, exposing all or part of the body for a certain exposure time. Prior to exposure in treatment units, an unaffected area of skin may be tested using UV skin-testing units in order to determine a suitable treatment regime. The exposure time at which barely perceptible erythema has developed is known as the Minimal Erythemal Dose (MED) for UVB therapy and Minimal Phototoxic Dose (MPD) for UVA therapy. This is used to determine the starting dose in the treatment regime. The presence of 'hotspots' and 'coldspots' in UV skin-testing units can result in inaccurate determination of MED/MPD. This could give rise to severe burns during treatment, or in a sub-optimal dose regime being used. Quality assurance protocols for UV phototherapy equipment have recently been developed and these protocols have highlighted the need for action levels for skin-testing units. An action level is a reference value, which is used to determine whether the difference in irradiance output level across a UV unit is acceptable. Current methodologies for skin-testing in Ireland have been characterised and errors introduced during testing have been estimated. Action levels have been developed based on analysis of errors and requirements of skin-testing.

Reduction of radiation exposure while maintaining high-quality fluoroscopic images during interventional cardiology using novel x-ray tube technology with extra beam filtering.

PubMed

den Boer, A; de Feyter, P J; Hummel, W A; Keane, D; Roelandt, J R

1994-06-01

Radiographic technology plays an integral role in interventional cardiology. The number of interventions continues to increase, and the associated radiation exposure to patients and personnel is of major concern. This study was undertaken to determine whether a newly developed x-ray tube deploying grid-switched pulsed fluoroscopy and extra beam filtering can achieve a reduction in radiation exposure while maintaining fluoroscopic images of high quality. Three fluoroscopic techniques were compared: continuous fluoroscopy, pulsed fluoroscopy, and a newly developed high-output pulsed fluoroscopy with extra filtering. To ascertain differences in the quality of images and to determine differences in patient entrance and investigator radiation exposure, the radiated volume curve was measured to determine the required high voltage levels (kVpeak) for different object sizes for each fluoroscopic mode. The fluoroscopic data of 124 patient procedures were combined. The data were analyzed for radiographic projections, image intensifier field size, and x-ray tube kilovoltage levels (kVpeak). On the basis of this analysis, a reference procedure was constructed. The reference procedure was tested on a phantom or dummy patient by all three fluoroscopic modes. The phantom was so designed that the kilovoltage requirements for each projection were comparable to those needed for the average patient. Radiation exposure of the operator and patient was measured during each mode. The patient entrance dose was measured in air, and the operator dose was measured by 18 dosimeters on a dummy operator. Pulsed compared with continuous fluoroscopy could be performed with improved image quality at lower kilovoltages. The patient entrance dose was reduced by 21% and the operator dose by 54%. High-output pulsed fluoroscopy with extra beam filtering compared with continuous fluoroscopy improved the image quality, lowered the kilovoltage requirements, and reduced the patient entrance dose by 55% and the operator dose by 69%. High-output pulsed fluoroscopy with a grid-switched tube and extra filtering improves the image quality and significantly reduces both the operator dose and patient dose.

Application of fluence field modulation to proton computed tomography for proton therapy imaging.

PubMed

Dedes, G; De Angelis, L; Rit, S; Hansen, D; Belka, C; Bashkirov, V; Johnson, R P; Coutrakon, G; Schubert, K E; Schulte, R W; Parodi, K; Landry, G

2017-07-12

This simulation study presents the application of fluence field modulated computed tomography, initially developed for x-ray CT, to proton computed tomography (pCT). By using pencil beam (PB) scanning, fluence modulated pCT (FMpCT) may achieve variable image quality in a pCT image and imaging dose reduction. Three virtual phantoms, a uniform cylinder and two patients, were studied using Monte Carlo simulations of an ideal list-mode pCT scanner. Regions of interest (ROI) were selected for high image quality and only PBs intercepting them preserved full fluence (FF). Image quality was investigated in terms of accuracy (mean) and noise (standard deviation) of the reconstructed proton relative stopping power compared to reference values. Dose calculation accuracy on FMpCT images was evaluated in terms of dose volume histograms (DVH), range difference (RD) for beam-eye-view (BEV) dose profiles and gamma evaluation. Pseudo FMpCT scans were created from broad beam experimental data acquired with a list-mode pCT prototype. FMpCT noise in ROIs was equivalent to FF images and accuracy better than  -1.3%(-0.7%) by using 1% of FF for the cylinder (patients). Integral imaging dose reduction of 37% and 56% was achieved for the two patients for that level of modulation. Corresponding DVHs from proton dose calculation on FMpCT images agreed to those from reference images and 96% of BEV profiles had RD below 2 mm, compared to only 1% for uniform 1% of FF. Gamma pass rates (2%, 2 mm) were 98% for FMpCT while for uniform 1% of FF they were as low as 59%. Applying FMpCT to preliminary experimental data showed that low noise levels and accuracy could be preserved in a ROI, down to 30% modulation. We have shown, using both virtual and experimental pCT scans, that FMpCT is potentially feasible and may allow a means of imaging dose reduction for a pCT scanner operating in PB scanning mode. This may be of particular importance to proton therapy given the low integral dose found outside the target.

Estimating Radiological Doses to Predators Foraging in a Low-Level Radioactive Waste Management Area

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

L.Soholt; G.Gonzales; P.Fresquez

2003-03-01

Since 1957, Los Alamos National Laboratory has operated Area G as its low-level, solid radioactive waste management and disposal area. Although the waste management area is developed, plants, small mammals, and avian and mammalian predators still occupy the less disturbed and revegetated portions of the land. For almost a decade, we have monitored the concentrations of selected radionuclides in soils, plants, and small mammals at Area G. The radionuclides tritium, plutonium-238, and plutonium-239 are regularly found at levels above regional background in all three media. Based on radionuclide concentrations in mice collected from 1994 to 1999, we calculated doses tomore » higher trophic levels (owl, hawk, kestrel, and coyote) that forage on the waste management area. These predators play important functions in the regional ecosystems and are an important part of local Native American traditional tales that identify the uniqueness of their culture. The estimated doses are compared to Department of Energy's interim limit of 0.1 rad/day for the protection of terrestrial wildlife. We used exposure parameters that were derived from the literature for each receptor, including Environmental Protection Agency's exposure factors handbook. Estimated doses to predators ranged from 9E-06 to 2E-04 rad/day, assuming that they forage entirely on the waste management area. These doses are greater than those calculated for predators foraging exclusively in reference areas, but are still well below the interim dose limit. We believe that these calculated doses represent upper-bound estimates of exposure for local predators because the larger predators forage over areas that are much greater than the 63-acre waste management area. Based on these results, we concluded that predators foraging on this area do not face a hazard from radiological exposure under current site conditions.« less

Characterization of a gated fiber-optic-coupled detector for application in clinical electron beam dosimetry

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

Tanyi, James A.; Nitzling, Kevin D.; Lodwick, Camille J.

2011-02-15

Purpose: Assessment of the fundamental dosimetric characteristics of a novel gated fiber-optic-coupled dosimetry system for clinical electron beam irradiation. Methods: The response of fiber-optic-coupled dosimetry system to clinical electron beam, with nominal energy range of 6-20 MeV, was evaluated for reproducibility, linearity, and output dependence on dose rate, dose per pulse, energy, and field size. The validity of the detector system's response was assessed in correspondence with a reference ionization chamber. Results: The fiber-optic-coupled dosimetry system showed little dependence to dose rate variations (coefficient of variation {+-}0.37%) and dose per pulse changes (with 0.54% of reference chamber measurements). The reproducibilitymore » of the system was {+-}0.55% for dose fractions of {approx}100 cGy. Energy dependence was within {+-}1.67% relative to the reference ionization chamber for the 6-20 MeV nominal electron beam energy range. The system exhibited excellent linear response (R{sup 2}=1.000) compared to reference ionization chamber in the dose range of 1-1000 cGy. The output factors were within {+-}0.54% of the corresponding reference ionization chamber measurements. Conclusions: The dosimetric properties of the gated fiber-optic-coupled dosimetry system compare favorably to the corresponding reference ionization chamber measurements and show considerable potential for applications in clinical electron beam radiotherapy.« less

Incorporation of detailed eye model into polygon-mesh versions of ICRP-110 reference phantoms

NASA Astrophysics Data System (ADS)

Tat Nguyen, Thang; Yeom, Yeon Soo; Kim, Han Sung; Wang, Zhao Jun; Han, Min Cheol; Kim, Chan Hyeong; Lee, Jai Ki; Zankl, Maria; Petoussi-Henss, Nina; Bolch, Wesley E.; Lee, Choonsik; Chung, Beom Sun

2015-11-01

The dose coefficients for the eye lens reported in ICRP 2010 Publication 116 were calculated using both a stylized model and the ICRP-110 reference phantoms, according to the type of radiation, energy, and irradiation geometry. To maintain consistency of lens dose assessment, in the present study we incorporated the ICRP-116 detailed eye model into the converted polygon-mesh (PM) version of the ICRP-110 reference phantoms. After the incorporation, the dose coefficients for the eye lens were calculated and compared with those of the ICRP-116 data. The results showed generally a good agreement between the newly calculated lens dose coefficients and the values of ICRP 2010 Publication 116. Significant differences were found for some irradiation cases due mainly to the use of different types of phantoms. Considering that the PM version of the ICRP-110 reference phantoms preserve the original topology of the ICRP-110 reference phantoms, it is believed that the PM version phantoms, along with the detailed eye model, provide more reliable and consistent dose coefficients for the eye lens.

Ionization chamber-based reference dosimetry of intensity modulated radiation beams.

PubMed

Bouchard, Hugo; Seuntjens, Jan

2004-09-01

The present paper addresses reference dose measurements using thimble ionization chambers for quality assurance in IMRT fields. In these radiation fields, detector fluence perturbation effects invalidate the application of open-field dosimetry protocol data for the derivation of absorbed dose to water from ionization chamber measurements. We define a correction factor C(Q)IMRT to correct the absorbed dose to water calibration coefficient N(D, w)Q for fluence perturbation effects in individual segments of an IMRT delivery and developed a calculation method to evaluate the factor. The method consists of precalculating, using accurate Monte Carlo techniques, ionization chamber, type-dependent cavity air dose, and in-phantom dose to water at the reference point for zero-width pencil beams as a function of position of the pencil beams impinging on the phantom surface. These precalculated kernels are convolved with the IMRT fluence distribution to arrive at the dose-to-water-dose-to-cavity air ratio [D(a)w (IMRT)] for IMRT fields and with a 10x10 cm2 open-field fluence to arrive at the same ratio D(a)w (Q) for the 10x10 cm2 reference field. The correction factor C(Q)IMRT is then calculated as the ratio of D(a)w (IMRT) and D(a)w (Q). The calculation method was experimentally validated and the magnitude of chamber correction factors in reference dose measurements in single static and dynamic IMRT fields was studied. The results show that, for thimble-type ionization chambers the correction factor in a single, realistic dynamic IMRT field can be of the order of 10% or more. We therefore propose that for accurate reference dosimetry of complete n-beam IMRT deliveries, ionization chamber fluence perturbation correction factors must explicitly be taken into account.

Effect of Study Design on Sample Size in Studies Intended to Evaluate Bioequivalence of Inhaled Short‐Acting β‐Agonist Formulations

PubMed Central

Zeng, Yaohui; Singh, Sachinkumar; Wang, Kai

2017-01-01

Abstract Pharmacodynamic studies that use methacholine challenge to assess bioequivalence of generic and innovator albuterol formulations are generally designed per published Food and Drug Administration guidance, with 3 reference doses and 1 test dose (3‐by‐1 design). These studies are challenging and expensive to conduct, typically requiring large sample sizes. We proposed 14 modified study designs as alternatives to the Food and Drug Administration–recommended 3‐by‐1 design, hypothesizing that adding reference and/or test doses would reduce sample size and cost. We used Monte Carlo simulation to estimate sample size. Simulation inputs were selected based on published studies and our own experience with this type of trial. We also estimated effects of these modified study designs on study cost. Most of these altered designs reduced sample size and cost relative to the 3‐by‐1 design, some decreasing cost by more than 40%. The most effective single study dose to add was 180 μg of test formulation, which resulted in an estimated 30% relative cost reduction. Adding a single test dose of 90 μg was less effective, producing only a 13% cost reduction. Adding a lone reference dose of either 180, 270, or 360 μg yielded little benefit (less than 10% cost reduction), whereas adding 720 μg resulted in a 19% cost reduction. Of the 14 study design modifications we evaluated, the most effective was addition of both a 90‐μg test dose and a 720‐μg reference dose (42% cost reduction). Combining a 180‐μg test dose and a 720‐μg reference dose produced an estimated 36% cost reduction. PMID:29281130

Reliability of Current Biokinetic and Dosimetric Models for Radionuclides: A Pilot Study

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

Leggett, Richard Wayne; Eckerman, Keith F; Meck, Robert A.

2008-10-01

This report describes the results of a pilot study of the reliability of the biokinetic and dosimetric models currently used by the U.S. Nuclear Regulatory Commission (NRC) as predictors of dose per unit internal or external exposure to radionuclides. The study examines the feasibility of critically evaluating the accuracy of these models for a comprehensive set of radionuclides of concern to the NRC. Each critical evaluation would include: identification of discrepancies between the models and current databases; characterization of uncertainties in model predictions of dose per unit intake or unit external exposure; characterization of variability in dose per unit intakemore » or unit external exposure; and evaluation of prospects for development of more accurate models. Uncertainty refers here to the level of knowledge of a central value for a population, and variability refers to quantitative differences between different members of a population. This pilot study provides a critical assessment of models for selected radionuclides representing different levels of knowledge of dose per unit exposure. The main conclusions of this study are as follows: (1) To optimize the use of available NRC resources, the full study should focus on radionuclides most frequently encountered in the workplace or environment. A list of 50 radionuclides is proposed. (2) The reliability of a dose coefficient for inhalation or ingestion of a radionuclide (i.e., an estimate of dose per unit intake) may depend strongly on the specific application. Multiple characterizations of the uncertainty in a dose coefficient for inhalation or ingestion of a radionuclide may be needed for different forms of the radionuclide and different levels of information of that form available to the dose analyst. (3) A meaningful characterization of variability in dose per unit intake of a radionuclide requires detailed information on the biokinetics of the radionuclide and hence is not feasible for many infrequently studied radionuclides. (4) The biokinetics of a radionuclide in the human body typically represents the greatest source of uncertainty or variability in dose per unit intake. (5) Characterization of uncertainty in dose per unit exposure is generally a more straightforward problem for external exposure than for intake of a radionuclide. (6) For many radionuclides the most important outcome of a large-scale critical evaluation of databases and biokinetic models for radionuclides is expected to be the improvement of current models. Many of the current models do not fully or accurately reflect available radiobiological or physiological information, either because the models are outdated or because they were based on selective or uncritical use of data or inadequate model structures. In such cases the models should be replaced with physiologically realistic models that incorporate a wider spectrum of information.« less

Establishment of institutional diagnostic reference level for computed tomography with automated dose-tracking software.

PubMed

Liang, Chong R; Chen, Priscilla X H; Kapur, Jeevesh; Ong, Michael K L; Quek, Swee T; Kapur, Subhash C

2017-06-01

The aim of this study was to establish institutional diagnostic reference levels (DRLs) by summarising doses collected across the five computed tomography (CT) system in our institution. CT dose data of 15940 patients were collected retrospectively from May 2015 to October 2015 in five institutional scanners. The mean, 75th percentile and 90th percentile of the dose spread were calculated according to anatomic region. The common CT examinations such as head, chest, combined abdomen/pelvis (A/P), and combined chest/abdomen/pelvis (C/A/P) were reviewed. Distribution of CT dose index (CTDIvol), dose-length product (DLP) and effective dose (ED) were extracted from the data for single-phasic and multiphasic examinations. The institutional DRL for our CT units were established as mean (50th percentile) of CTDIvol (mGy), DLP (mGy.cm) and ED (mSv) for single and multiphasic studies using the dose-tracking software. In single phasic examination, Head: (49.0 mGy), (978.0 mGy.cm), (2.4 mSv) respectively; Chest: (6.0 mGy), (254.0 mGy.cm), (4.9 mSv) respectively; CT A/P (10.0 mGy), (514.0 mGy.cm), (8.9 mSv) respectively; CT C/A/P (10.0 mGy), (674.0 mGy.cm), (11.8 mSv) respectively. In multiphasic studies: Head (45.0 mGy), (1822.0 mGy.cm), (5.0 mSv) respectively; Chest (8.0 mGy), (577.0 mGy.cm), (10.0 mSv) respectively; CT A/P: (10.0 mGy), (1153.0 mGy.cm), (20.2 mSv) respectively; CT C/A/P: (11.0 mGy), (1090.0 mGy.cm), (19.2 mSv) respectively. The reported metrics offer a variety of information that institutions can use for quality improvement activities. The variations in dose between scanners suggest a large potential for optimisation of radiation dose. © 2017 The Authors. Journal of Medical Radiation Sciences published by John Wiley & Sons Australia, Ltd on behalf of Australian Society of Medical Imaging and Radiation Therapy and New Zealand Institute of Medical Radiation Technology.

Predicting rapid analgesic onset of ibuprofen salts compared with ibuprofen acid: Tlag, Tlow, Tmed, and a novel parameter, TCmaxRef.

PubMed

Miles, Lisa; Hall, Jessica; Jenner, Bartosz; Addis, Richard; Hutchings, Simon

2018-04-27

This study evaluated the early absorption characteristics of ibuprofen salt formulations and standard ibuprofen acid (the reference). In this open-label, crossover, single-center study (NCT02452450) in 32 healthy, fasted adults receiving single oral doses (400 mg ibuprofen) of ibuprofen lysine, ibuprofen liquid capsule, ibuprofen sodium, ibuprofen acid, and paracetamol, intensive blood sampling was conducted for up to 6 h. Time between dosing and the start of absorption (T lag ); a novel parameter, time at which the test formulations (ibuprofen salts) reached the observed maximum plasma concentration (C max ) of the reference (standard ibuprofen acid) (T C maxRef ); and time to achieve therapeutic plasma concentration were measured. Ibuprofen was absorbed more rapidly from the salt formulations than the reference; T lag was 3.3-6.4 min for salt formulations compared with 10.9 min for the reference, and 100% of subjects had a T lag ≤ 5 min for ibuprofen lysine, compared with 61% for ibuprofen liquid capsule, 21% for ibuprofen sodium, and 7% for the reference. T C maxRef was 3.22-5.74-times shorter for salt formulations than for the reference (all p < .0001). The salt formulations reached therapeutic levels earlier than the reference (all p < .0001). All formulations were well tolerated. This study shows that ibuprofen salts are absorbed faster than ibuprofen acid. T lag and T C maxRef demonstrated early start and increased speed of absorption of salts compared with the reference, and may predict more rapid onset of analgesia.

Demand- and supply-side determinants of diphtheria-pertussis-tetanus nonvaccination and dropout in rural India.

PubMed

Ghosh, Arpita; Laxminarayan, Ramanan

2017-02-15

Although 93% of 12- to 23-month-old children in India receive at least one vaccine, typically Bacillus Calmette-Guérin, only 75% complete the recommended three doses of diphtheria-pertussis-tetanus (DPT, also referred to as DTP) vaccine. Determinants can be different for nonvaccination and dropout but have not been examined in earlier studies. We use the three-dose DPT series as a proxy for the full sequence of recommended childhood vaccines and examine the determinants of DPT nonvaccination and dropout between doses 1 and 3. We analyzed data on 75,728 6- to 23-month-old children in villages across India to study demand- and supply-side factors determining nonvaccination with DPT and dropout between DPT doses 1 and 3, using a multilevel approach. Data come from the District Level Household and Facility Survey 3 (2007-08). Individual- and household-level factors were associated with both DPT nonvaccination and dropout between doses 1 and 3. Children whose mothers had no schooling were 2.3 times more likely not to receive any DPT vaccination and 1.5 times more likely to drop out between DPT doses 1 and 3, compared with children whose mothers had 10 or more years of schooling. Although supply-side factors related to availability of public health facilities and immunization-related health workers in villages were not correlated with dropout between DPT doses 1 and 3, children in districts where 46% or more villages had a healthcare subcentre were 1.5 times more likely to receive at least one dose of DPT vaccine compared with children in districts where 30% or fewer villages had subcentres. Nonvaccination with DPT in India is influenced by village- and district-level contextual factors over and above individuals' background characteristics. Dropout between DPT doses 1 and 3 is associated more strongly with demand-side factors than with village- and district-level supply-side factors. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

TU-D-209-03: Alignment of the Patient Graphic Model Using Fluoroscopic Images for Skin Dose Mapping

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

Oines, A; Oines, A; Kilian-Meneghin, J

2016-06-15

Purpose: The Dose Tracking System (DTS) was developed to provide realtime feedback of skin dose and dose rate during interventional fluoroscopic procedures. A color map on a 3D graphic of the patient represents the cumulative dose distribution on the skin. Automated image correlation algorithms are described which use the fluoroscopic procedure images to align and scale the patient graphic for more accurate dose mapping. Methods: Currently, the DTS employs manual patient graphic selection and alignment. To improve the accuracy of dose mapping and automate the software, various methods are explored to extract information about the beam location and patient morphologymore » from the procedure images. To match patient anatomy with a reference projection image, preprocessing is first used, including edge enhancement, edge detection, and contour detection. Template matching algorithms from OpenCV are then employed to find the location of the beam. Once a match is found, the reference graphic is scaled and rotated to fit the patient, using image registration correlation functions in Matlab. The algorithm runs correlation functions for all points and maps all correlation confidences to a surface map. The highest point of correlation is used for alignment and scaling. The transformation data is saved for later model scaling. Results: Anatomic recognition is used to find matching features between model and image and image registration correlation provides for alignment and scaling at any rotation angle with less than onesecond runtime, and at noise levels in excess of 150% of those found in normal procedures. Conclusion: The algorithm provides the necessary scaling and alignment tools to improve the accuracy of dose distribution mapping on the patient graphic with the DTS. Partial support from NIH Grant R01-EB002873 and Toshiba Medical Systems Corp.« less

SU-F-T-170: Patient Surface Dose Measurements Using Optically Stimulated Luminescence Dosimeters in Scanning Proton Beam Therapy for Breast Cancer

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

Yu, J; Strauss, D; Langner, U

Purpose: To establish patient surface dose dosimetry for scanning proton beam therapy (SPBT) for breast cancer using optically stimulated luminescence dosimeters (OSLD). Methods: OSLDs were calibrated with SPB under the similar conditions as the treatments for breast cancer. A range shifter (RS) of 5 cm water equivalent thickness (WET) was used. The air gap from the surface of the range shifter to the surface of the phantom was 15 cm. A uniform planar dose generated by nominal energy of 118 MeV was delivered. The range of 118 MeV proton beam after the 5cm RS is approximately 5 cm in water,more » which is the common range for breast treatments. The OSLDs were placed on the surface of high density polyethylene slabs, and a bolus of 1.06 cm WET was used for buildup. A variety of dose levels in the range of 0.5 to 8 Gy were delivered. Under the same condition, an ADCL calibrated parallel plate (PP) chamber was used to measure the reference dose. The correlation between the output signals of OSLDs and the reference doses was established. The calibration of OSLD was verified against the PP chamber measurements for two SPBT breast plans calculated for two patients. Results: the least squares fitting for the OSLD calibration curve was a polynomial function to the order of 2 in the range of 0.5 to 8 Gy (RBE). The differences between the dose measured with OSLDs and PP chamber were within 3% for the two breast proton plans. Conclusion: the calibrated OSLDs under the similar conditions as the treatments can be used for patient surface dose measurements.« less

Model-based iterative reconstruction and adaptive statistical iterative reconstruction: dose-reduced CT for detecting pancreatic calcification.

PubMed

Yasaka, Koichiro; Katsura, Masaki; Akahane, Masaaki; Sato, Jiro; Matsuda, Izuru; Ohtomo, Kuni

2016-01-01

Iterative reconstruction methods have attracted attention for reducing radiation doses in computed tomography (CT). To investigate the detectability of pancreatic calcification using dose-reduced CT reconstructed with model-based iterative construction (MBIR) and adaptive statistical iterative reconstruction (ASIR). This prospective study approved by Institutional Review Board included 85 patients (57 men, 28 women; mean age, 69.9 years; mean body weight, 61.2 kg). Unenhanced CT was performed three times with different radiation doses (reference-dose CT [RDCT], low-dose CT [LDCT], ultralow-dose CT [ULDCT]). From RDCT, LDCT, and ULDCT, images were reconstructed with filtered-back projection (R-FBP, used for establishing reference standard), ASIR (L-ASIR), and MBIR and ASIR (UL-MBIR and UL-ASIR), respectively. A lesion (pancreatic calcification) detection test was performed by two blinded radiologists with a five-point certainty level scale. Dose-length products of RDCT, LDCT, and ULDCT were 410, 97, and 36 mGy-cm, respectively. Nine patients had pancreatic calcification. The sensitivity for detecting pancreatic calcification with UL-MBIR was high (0.67-0.89) compared to L-ASIR or UL-ASIR (0.11-0.44), and a significant difference was seen between UL-MBIR and UL-ASIR for one reader (P = 0.014). The area under the receiver-operating characteristic curve for UL-MBIR (0.818-0.860) was comparable to that for L-ASIR (0.696-0.844). The specificity was lower with UL-MBIR (0.79-0.92) than with L-ASIR or UL-ASIR (0.96-0.99), and a significant difference was seen for one reader (P < 0.01). In UL-MBIR, pancreatic calcification can be detected with high sensitivity, however, we should pay attention to the slightly lower specificity.

Individualized adjustments to reference phantom internal organ dosimetry—scaling factors given knowledge of patient external anatomy

NASA Astrophysics Data System (ADS)

Wayson, Michael B.; Bolch, Wesley E.

2018-04-01

Internal radiation dose estimates for diagnostic nuclear medicine procedures are typically calculated for a reference individual. Resultantly, there is uncertainty when determining the organ doses to patients who are not at 50th percentile on either height or weight. This study aims to better personalize internal radiation dose estimates for individual patients by modifying the dose estimates calculated for reference individuals based on easily obtainable morphometric characteristics of the patient. Phantoms of different sitting heights and waist circumferences were constructed based on computational reference phantoms for the newborn, 10 year-old, and adult. Monoenergetic photons and electrons were then simulated separately at 15 energies. Photon and electron specific absorbed fractions (SAFs) were computed for the newly constructed non-reference phantoms and compared to SAFs previously generated for the age-matched reference phantoms. Differences in SAFs were correlated to changes in sitting height and waist circumference to develop scaling factors that could be applied to reference SAFs as morphometry corrections. A further set of arbitrary non-reference phantoms were then constructed and used in validation studies for the SAF scaling factors. Both photon and electron dose scaling methods were found to increase average accuracy when sitting height was used as the scaling parameter (~11%). Photon waist circumference-based scaling factors showed modest increases in average accuracy (~7%) for underweight individuals, but not for overweight individuals. Electron waist circumference-based scaling factors did not show increases in average accuracy. When sitting height and waist circumference scaling factors were combined, modest average gains in accuracy were observed for photons (~6%), but not for electrons. Both photon and electron absorbed doses are more reliably scaled using scaling factors computed in this study. They can be effectively scaled using sitting height alone as patient-specific morphometric parameter.

Individualized adjustments to reference phantom internal organ dosimetry-scaling factors given knowledge of patient external anatomy.

PubMed

Wayson, Michael B; Bolch, Wesley E

2018-04-13

Internal radiation dose estimates for diagnostic nuclear medicine procedures are typically calculated for a reference individual. Resultantly, there is uncertainty when determining the organ doses to patients who are not at 50th percentile on either height or weight. This study aims to better personalize internal radiation dose estimates for individual patients by modifying the dose estimates calculated for reference individuals based on easily obtainable morphometric characteristics of the patient. Phantoms of different sitting heights and waist circumferences were constructed based on computational reference phantoms for the newborn, 10 year-old, and adult. Monoenergetic photons and electrons were then simulated separately at 15 energies. Photon and electron specific absorbed fractions (SAFs) were computed for the newly constructed non-reference phantoms and compared to SAFs previously generated for the age-matched reference phantoms. Differences in SAFs were correlated to changes in sitting height and waist circumference to develop scaling factors that could be applied to reference SAFs as morphometry corrections. A further set of arbitrary non-reference phantoms were then constructed and used in validation studies for the SAF scaling factors. Both photon and electron dose scaling methods were found to increase average accuracy when sitting height was used as the scaling parameter (~11%). Photon waist circumference-based scaling factors showed modest increases in average accuracy (~7%) for underweight individuals, but not for overweight individuals. Electron waist circumference-based scaling factors did not show increases in average accuracy. When sitting height and waist circumference scaling factors were combined, modest average gains in accuracy were observed for photons (~6%), but not for electrons. Both photon and electron absorbed doses are more reliably scaled using scaling factors computed in this study. They can be effectively scaled using sitting height alone as patient-specific morphometric parameter.

Reference gene selection for normalization of RT-qPCR gene expression data from Actinidia deliciosa leaves infected with Pseudomonas syringae pv. actinidiae

PubMed Central

Petriccione, Milena; Mastrobuoni, Francesco; Zampella, Luigi; Scortichini, Marco

2015-01-01

Normalization of data, by choosing the appropriate reference genes (RGs), is fundamental for obtaining reliable results in reverse transcription-quantitative PCR (RT-qPCR). In this study, we assessed Actinidia deliciosa leaves inoculated with two doses of Pseudomonas syringae pv. actinidiae during a period of 13 days for the expression profile of nine candidate RGs. Their expression stability was calculated using four algorithms: geNorm, NormFinder, BestKeeper and the deltaCt method. Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and protein phosphatase 2A (PP2A) were the most stable genes, while β-tubulin and 7s-globulin were the less stable. Expression analysis of three target genes, chosen for RGs validation, encoding the reactive oxygen species scavenging enzymes ascorbate peroxidase (APX), superoxide dismutase (SOD) and catalase (CAT) indicated that a combination of stable RGs, such as GAPDH and PP2A, can lead to an accurate quantification of the expression levels of such target genes. The APX level varied during the experiment time course and according to the inoculum doses, whereas both SOD and CAT resulted down-regulated during the first four days, and up-regulated afterwards, irrespective of inoculum dose. These results can be useful for better elucidating the molecular interaction in the A. deliciosa/P. s. pv. actinidiae pathosystem and for RGs selection in bacteria-plant pathosystems. PMID:26581656

Interim methods for development of inhalation reference concentrations. Draft report

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

Blackburn, K.; Dourson, M.; Erdreich, L.

1990-08-01

An inhalation reference concentration (RfC) is an estimate of continuous inhalation exposure over a human lifetime that is unlikely to pose significant risk of adverse noncancer health effects and serves as a benchmark value for assisting in risk management decisions. Derivation of an RfC involves dose-response assessment of animal data to determine the exposure levels at which no significant increase in the frequency or severity of adverse effects between the exposed population and its appropriate control exists. The assessment requires an interspecies dose extrapolation from a no-observed-adverse-effect level (NOAEL) exposure concentration of an animal to a human equivalent NOAEL (NOAEL(HBC)).more » The RfC is derived from the NOAEL(HBC) by the application of generally order-of-magnitude uncertainty factors. Intermittent exposure scenarios in animals are extrapolated to chronic continuous human exposures. Relationships between external exposures and internal doses depend upon complex simultaneous and consecutive processes of absorption, distribution, metabolism, storage, detoxification, and elimination. To estimate NOAEL(HBC)s when chemical-specific physiologically-based pharmacokinetic models are not available, a dosimetric extrapolation procedure based on anatomical and physiological parameters of the exposed human and animal and the physical parameters of the toxic chemical has been developed which gives equivalent or more conservative exposure concentrations values than those that would be obtained with a PB-PK model.« less

Effect of ultra-low doses, ASIR and MBIR on density and noise levels of MDCT images of dental implant sites.

PubMed

Widmann, Gerlig; Al-Shawaf, Reema; Schullian, Peter; Al-Sadhan, Ra'ed; Hörmann, Romed; Al-Ekrish, Asma'a A

2017-05-01

Differences in noise and density values in MDCT images obtained using ultra-low doses with FBP, ASIR, and MBIR may possibly affect implant site density analysis. The aim of this study was to compare density and noise measurements recorded from dental implant sites using ultra-low doses combined with FBP, ASIR, and MBIR. Cadavers were scanned using a standard protocol and four low-dose protocols. Scans were reconstructed using FBP, ASIR-50, ASIR-100, and MBIR, and either a bone or standard reconstruction kernel. Density (mean Hounsfield units [HUs]) of alveolar bone and noise levels (mean standard deviation of HUs) was recorded from all datasets and measurements were compared by paired t tests and two-way ANOVA with repeated measures. Significant differences in density and noise were found between the reference dose/FBP protocol and almost all test combinations. Maximum mean differences in HU were 178.35 (bone kernel) and 273.74 (standard kernel), and in noise, were 243.73 (bone kernel) and 153.88 (standard kernel). Decreasing radiation dose increased density and noise regardless of reconstruction technique and kernel. The effect of reconstruction technique on density and noise depends on the reconstruction kernel used. • Ultra-low-dose MDCT protocols allowed more than 90 % reductions in dose. • Decreasing the dose generally increased density and noise. • Effect of IRT on density and noise varies with reconstruction kernel. • Accuracy of low-dose protocols for interpretation of bony anatomy not known. • Effect of low doses on accuracy of computer-aided design models unknown.

Local patient dose diagnostic reference levels in pediatric interventional cardiology in Chile using age bands and patient weight values

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

Ubeda, Carlos, E-mail: cubeda@uta.cl; Miranda, Patricia; Vano, Eliseo

Purpose: To present the results of a patient dose evaluation program in pediatric cardiology and propose local diagnostic reference levels (DRLs) for different types of procedure and age range, in addition to suggesting approaches to correlate patient dose values with patient weight. This study was the first conducted in Latin America for pediatric interventional cardiology under the auspices of the International Atomic Energy Agency. Methods: Over three years, the following data regarding demographic and patient dose values were collected: age, gender, weight, height, number of cine series, total number of cine frames, fluoroscopy time (FT), and two dosimetric quantities, dose-areamore » product (DAP) and cumulative dose (CD), at the patient entrance reference point. The third quartile values for FT, DAP, CD, number of cine series, and the DAP/body weight ratio were proposed as the set of quantities to use as local DRLs. Results: Five hundred and seventeen patients were divided into four age groups. Sample sizes by age group were 120 for <1 yr; 213 for 1 to <5 yr; 82 for 5 to <10 yr; and 102 for 10 to <16 yr. The third quartile values obtained for DAP by diagnostic and therapeutic procedures and age range were 1.17 and 1.11 Gy cm{sup 2} for <1 yr; 1.74 and 1.90 Gy cm{sup 2} for 1 to <5 yr; 2.83 and 3.22 Gy cm{sup 2} for 5 to <10 yr; and 7.34 and 8.68 Gy cm{sup 2} for 10 to <16 yr, respectively. The third quartile value obtained for the DAP/body weight ratio for the full sample of procedures was 0.17 (Gy cm{sup 2}/kg) for diagnostic and therapeutic procedures. Conclusions: The data presented in this paper are an initial attempt at establishing local DRLs in pediatric interventional cardiology, from a large sample of procedures for the standard age bands used in Europe, complemented with the values of the ratio between DAP and patient weight. This permits a rough estimate of DRLs for different patient weights and the refining of these values for the age bands when there may be large differences in child size. These DRLs were obtained at the largest pediatric hospital in Chile, with an active optimization program, and could be used by other hospitals in the Latin America region to compare their current patient dose values and determine whether corrective action is appropriate.« less

Local patient dose diagnostic reference levels in pediatric interventional cardiology in Chile using age bands and patient weight values.

PubMed

Ubeda, Carlos; Miranda, Patricia; Vano, Eliseo

2015-02-01

To present the results of a patient dose evaluation program in pediatric cardiology and propose local diagnostic reference levels (DRLs) for different types of procedure and age range, in addition to suggesting approaches to correlate patient dose values with patient weight. This study was the first conducted in Latin America for pediatric interventional cardiology under the auspices of the International Atomic Energy Agency. Over three years, the following data regarding demographic and patient dose values were collected: age, gender, weight, height, number of cine series, total number of cine frames, fluoroscopy time (FT), and two dosimetric quantities, dose-area product (DAP) and cumulative dose (CD), at the patient entrance reference point. The third quartile values for FT, DAP, CD, number of cine series, and the DAP/body weight ratio were proposed as the set of quantities to use as local DRLs. Five hundred and seventeen patients were divided into four age groups. Sample sizes by age group were 120 for <1 yr; 213 for 1 to <5 yr; 82 for 5 to <10 yr; and 102 for 10 to <16 yr. The third quartile values obtained for DAP by diagnostic and therapeutic procedures and age range were 1.17 and 1.11 Gy cm 2 for <1 yr; 1.74 and 1.90 Gy cm 2 for 1 to <5 yr; 2.83 and 3.22 Gy cm 2 for 5 to <10 yr; and 7.34 and 8.68 Gy cm 2 for 10 to <16 yr, respectively. The third quartile value obtained for the DAP/body weight ratio for the full sample of procedures was 0.17 (Gy cm 2 /kg) for diagnostic and therapeutic procedures. The data presented in this paper are an initial attempt at establishing local DRLs in pediatric interventional cardiology, from a large sample of procedures for the standard age bands used in Europe, complemented with the values of the ratio between DAP and patient weight. This permits a rough estimate of DRLs for different patient weights and the refining of these values for the age bands when there may be large differences in child size. These DRLs were obtained at the largest pediatric hospital in Chile, with an active optimization program, and could be used by other hospitals in the Latin America region to compare their current patient dose values and determine whether corrective action is appropriate. © 2015 American Association of Physicists in Medicine.

Development and validation of RAYDOSE: a Geant4-based application for molecular radiotherapy

NASA Astrophysics Data System (ADS)

Marcatili, S.; Pettinato, C.; Daniels, S.; Lewis, G.; Edwards, P.; Fanti, S.; Spezi, E.

2013-04-01

We developed and validated a Monte-Carlo-based application (RAYDOSE) to generate patient-specific 3D dose maps on the basis of pre-treatment imaging studies. A CT DICOM image is used to model patient geometry, while repeated PET scans are employed to assess radionuclide kinetics and distribution at the voxel level. In this work, we describe the structure of this application and present the tests performed to validate it against reference data and experiments. We used the spheres of a NEMA phantom to calculate S values and total doses. The comparison with reference data from OLINDA/EXM showed an agreement within 2% for a sphere size above 2.8 cm diameter. A custom heterogeneous phantom composed of several layers of Perspex and lung equivalent material was used to compare TLD measurements of gamma radiation from 131I to Monte Carlo simulations. An agreement within 5% was found. RAYDOSE has been validated against reference data and experimental measurements and can be a useful multi-modality platform for treatment planning and research in MRT.

Comparison of reference doses (RfDs) developed for the protection of wildlife species in contrast to humans

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

Valoppi, L.; Carlisle, J.; Polisini, J.

1995-12-31

A component of both human health and ecological risk assessments is the evaluation of toxicity values. A comparison between the methodology for the development of Reference Doses (RfDs) to be protective of humans, and that developed for vertebrate wildlife species is presented. For all species, a chronic No Observable Adverse Effect Level (NOAEL) is developed by applying uncertainty factors (UFs) to literature-based toxicity values. Uncertainty factors are used to compensate for the length of exposure, sensitivity of endpoints, and cross-species extrapolations between the test species and the species being assessed. Differences between human and wildlife species could include the toxicologicalmore » endpoint, the critical study, and the magnitude of the cross-species extrapolation factor. Case studies for select chemicals are presented which contrast RfDs developed for humans and those developed for avian and mammalian wildlife.« less

Ultralow Dose MSCT Imaging in Dental Implantology

PubMed Central

Widmann, Gerlig; Al-Ekrish, Asma'a A.

2018-01-01

Introduction: The Council Directive 2013/59 Euratom has a clear commitment for keeping medical radiation exposure as low as reasonably achievable and demands a regular review and use of diagnostic reference levels. Methods: In dental implantology, the range of effective doses for cone beam computed tomography (CBCT) shows a broad overlap with multislice computed tomography (MSCT). More recently, ultralow dose imaging with new generations of MSCT scanners may impart radiation doses equal to or lower than CBCT. Dose reductions in MSCT have been further facilitated by the introduction of iterative image reconstruction technology (IRT), which provides substantial noise reduction over the current standard of filtered backward projection (FBP). Aim: The aim of this article is to review the available literature on ultralow dose CT imaging and IRTs in dental implantology imaging and to summarize their influence on spatial and contrast resolution, image noise, tissue density measurements, and validity of linear measurements of the jaws. Conclusion: Application of ultralow dose MSCT with IRT technology in dental implantology offers the potential for very large dose reductions compared with standard dose imaging. Yet, evaluation of various diagnostic tasks related to dental implantology is still needed to confirm the results obtained with various IRTs and ultra-low doses so far. PMID:29492174

Hypovitaminosis D in Bariatric Surgery: A Systematic Review of Observational Studies

PubMed Central

Chakhtoura, M; Nakhoul, N; Shawwa, K; Mantzoros, C; El Hajj Fuleihan, G

2016-01-01

Background Obesity is a public health problem that carries global and substantial social and economic burden. Relative to non-surgical interventions, bariatric surgery has the most substantial and lasting impact on weight loss. However, it leads to a number of nutritional deficiencies requiring long term supplementation. Objectives The aims of this paper are to review 25-hydroxyvitamin D [25(OH)D] status pre and post - bariatric surgery, describe the dose response of vitamin D supplementation, and assess the effect of the surgical procedure on 25(OH)D level following supplementation. Methods We searched Medline, PubMed, the Cochrane Library and EMBASE, for relevant observational studies published in English, from 2000–April 2015. The identified references were reviewed, in duplicate and independently, by two reviewers. Results We identified 51 eligible observational studies assessing 25(OH)D status pre and/or post bariatric surgery. Mean pre-surgery 25(OH)D level was below 30 ng/ml in 29 studies and 17 of these studies showed mean 25(OH)D levels ≤ 20 ng/ml. Mean 25(OH)D levels remained below 30 ng/ml following bariatric surgery despite various vitamin D replacement regimens, with only few exceptions. The increase in postoperative 25(OH)D levels tended to parallel increments in vitamin D supplementation dose but varied widely across studies. An increase in 25(OH)D level by 9–13 ng/ml was achieved when vitamin D deficiency was corrected using vitamin D replacement doses of 1,100–7,100 IU/day, in addition to the usual maintenance equivalent daily dose of 400 – 2,000 IU (total equivalent daily dose 1,500–9,150 IU). There was no difference in mean 25(OH)D level following supplementation between malabsorptive/ combination procedures and restrictive procedures. Conclusion Hypovitaminosisis D persists in obese patients undergoing bariatric surgery, despite various vitamin D supplementation regimens. Further research is needed to determine the optimal vitamin D dose to reach desirable 25(OH)D levels in this population, and to demonstrate whether this dose varies according to the surgical procedure. PMID:26805016

Evaluation of six TPS algorithms in computing entrance and exit doses

PubMed Central

Metwaly, Mohamed; Glegg, Martin; Baggarley, Shaun P.; Elliott, Alex

2014-01-01

Entrance and exit doses are commonly measured in in vivo dosimetry for comparison with expected values, usually generated by the treatment planning system (TPS), to verify accuracy of treatment delivery. This report aims to evaluate the accuracy of six TPS algorithms in computing entrance and exit doses for a 6 MV beam. The algorithms tested were: pencil beam convolution (Eclipse PBC), analytical anisotropic algorithm (Eclipse AAA), AcurosXB (Eclipse AXB), FFT convolution (XiO Convolution), multigrid superposition (XiO Superposition), and Monte Carlo photon (Monaco MC). Measurements with ionization chamber (IC) and diode detector in water phantoms were used as a reference. Comparisons were done in terms of central axis point dose, 1D relative profiles, and 2D absolute gamma analysis. Entrance doses computed by all TPS algorithms agreed to within 2% of the measured values. Exit doses computed by XiO Convolution, XiO Superposition, Eclipse AXB, and Monaco MC agreed with the IC measured doses to within 2%‐3%. Meanwhile, Eclipse PBC and Eclipse AAA computed exit doses were higher than the IC measured doses by up to 5.3% and 4.8%, respectively. Both algorithms assume that full backscatter exists even at the exit level, leading to an overestimation of exit doses. Despite good agreements at the central axis for Eclipse AXB and Monaco MC, 1D relative comparisons showed profiles mismatched at depths beyond 11.5 cm. Overall, the 2D absolute gamma (3%/3 mm) pass rates were better for Monaco MC, while Eclipse AXB failed mostly at the outer 20% of the field area. The findings of this study serve as a useful baseline for the implementation of entrance and exit in vivo dosimetry in clinical departments utilizing any of these six common TPS algorithms for reference comparison. PACS numbers: 87.55.‐x, 87.55.D‐, 87.55.N‐, 87.53.Bn PMID:24892349

Range and trend of expected toxicity level (ETL) in standard A + B designs: a report from the Children's Oncology Group.

PubMed

Chen, Zhengjia; Krailo, Mark D; Sun, Junfeng; Azen, Stanley P

2009-03-01

The traditional algorithm-based 3+3 designs are most widely used for their practical simplicity in phase I clinical trials. At early stage, a common belief was that the expected toxicity level (ETL) at the maximum tolerated dose (MTD) should be 33% [Storer, B. Design and analysis of phase I clinical trials. Biometrics 1989;45;925-937, Gorden, N., Willson, J. Using toxicity grades in the design and analysis of cancer phase I clinical trials. Statistics in Medicine 1992; 11: 2063-2075, Mick, R. Phase I Clinical Trial Design. In Schilsky, R., Milano, G., Ratain, M., eds. Principles of Antineoplastic Drug Development and Pharmacology New York, NY: Marcel Dekker, 1996; 29-36]. Recently, Kang and Ahn [Kang, S., Ahn, C. The expected toxicity rate at the maximum tolerated dose in the standard phase I cancer clinical trial design. Drug Information Journal 2001; 35:1189-1199, Kang, S., Ahn, C. An investigation of the traditional algorithm-based designs for phase I cancer clinical trials. Drug Information Journal 2002; 36:865-873] found that the ETL is between 17% and 21% and He et al [He, W., Liu, J., Binkowitz, B., Quan, H. A model-based approach in the estimation of the maximum tolerated dose in phase I cancer clinical trials. Statistics in Medicine 2006; 25(12):2027-42] further reported that the ETL ranges from 19% to 24%. However they only investigated designs where the number of dose levels was at most 20. It has practical significance in designing and conducting phase I clinical trial to definitely assess the full range and trend of ETL by all possible number of tested dose levels in traditional algorithm-based A+B designs, especially 3+3 designs. In this simulation study, we originally find that the ETL decreases monotonically from about 30% to 0% as the number of dose levels increase from 3 to infinity, which will correct the inaccuracy in the common belief among phase I trial investigators. To help better design and conduct phase I trials, we create a table as a reference for the association between ETL and number of dose levels considered in a design when the exact shape of the dose-toxicity relationship is not well understood. We conclude that the number of specified dose levels is an important factor affecting substantially the ETL at MTD and recommend that fewer than 20 dose levels be designated.

Site-Specific Reference Person Parameters and Derived Concentration Standards for the Savannah River Site

DOE PAGES

Stone, Daniel K.; Higley, Kathryn A.; Jannik, G. Timothy

2014-05-01

The U.S. Department of Energy Order 458.1 states that the compliance with the 1 mSv annual dose constraint to a member of the public may be demonstrated by calculating dose to the maximally exposed individual (MEI) or to a representative person. Historically, the MEI concept was used for dose compliance at the Savannah River Site (SRS) using adult dose coefficients and adult male usage parameters. For future compliance, SRS plans to use the representative person concept for dose estimates to members of the public. The representative person dose will be based on the reference person dose coefficients from the U.S.more » DOE Derived Concentration Technical Standard and on usage parameters specific to SRS for the reference and typical person. Usage parameters and dose coefficients were determined for inhalation, ingestion and external exposure pathways. The parameters for the representative person were used to calculate and tabulate SRS-specific derived concentration standards (DCSs) for the pathways not included in DOE-STD-1196-2011.« less

Fructo-oligosaccharide improved brain β-amyloid, β-secretase, cognitive function, and plasma antioxidant levels in D-galactose-treated Balb/cJ mice.

PubMed

Yen, Chi-Hua; Wang, Cheng-Hsin; Wu, Wen-Tzu; Chen, Hsiao-Ling

2017-05-01

Long-term d-galactose injection induces accelerated aging in experimental rodent models. The aim of this study was to determine the effects of dietary fructo-oligosaccharide (FO) on the brain β-amyloid (Aβ), amyloid-associated enzymes, cognitive function, and plasma antioxidant levels in d-galactose-treated Balb/c mice. The subcutaneous (s.c.) injection and the dietary treatment were conducted simultaneously for 49 days. Mice (12 weeks of age) were divided into five groups (n = 14/group): control (s.c. saline, control diet) serving as a young control, DG (s.c. 1.2 g d-galactose/kg body weight, control diet), DG + LFO (2.5% w/w FO, low-dose FO diet), DG + HFO (5% w/w FO, high-dose FO diet), and DG + E (α-tocopherol 0.2% w/w, vitamin E diet) as an antioxidant reference group. Another group of older mice (64 weeks of age) without any injection served as a natural aging (NA) group. The DG and NA groups had greater Aβ levels in the cortex, hippocampus, and the whole brain. High-dose FO, similar to α-tocopherol, attenuated the d-galactose-induced Aβ density in the cortex and hippocampus. In addition, FO attenuated the d-galactose-induced protein expression of Aβ and beta-site amyloid precursor cleaving enzyme of the whole brain in a dose-response manner. Either dose of FO supplementation, similar to α-tocopherol, attenuated the d-galactose-induced cognitive dysfunction. In addition, FO improved the plasma ascorbic acid level in a dose-response manner. Dietary FO (2.5-5% w/w diet) could attenuate the development of Alzheimer's disease, which was likely to be associated with its systematic antioxidant effects.

Microionization chamber for reference dosimetry in IMRT verification: clinical implications on OAR dosimetric errors

NASA Astrophysics Data System (ADS)

Sánchez-Doblado, Francisco; Capote, Roberto; Leal, Antonio; Roselló, Joan V.; Lagares, Juan I.; Arráns, Rafael; Hartmann, Günther H.

2005-03-01

Intensity modulated radiotherapy (IMRT) has become a treatment of choice in many oncological institutions. Small fields or beamlets with sizes of 1 to 5 cm2 are now routinely used in IMRT delivery. Therefore small ionization chambers (IC) with sensitive volumes <=0.1 cm3are generally used for dose verification of an IMRT treatment. The measurement conditions during verification may be quite different from reference conditions normally encountered in clinical beam calibration, so dosimetry of these narrow photon beams pertains to the so-called non-reference conditions for beam calibration. This work aims at estimating the error made when measuring the organ at risk's (OAR) absolute dose by a micro ion chamber (μIC) in a typical IMRT treatment. The dose error comes from the assumption that the dosimetric parameters determining the absolute dose are the same as for the reference conditions. We have selected two clinical cases, treated by IMRT, for our dose error evaluations. Detailed geometrical simulation of the μIC and the dose verification set-up was performed. The Monte Carlo (MC) simulation allows us to calculate the dose measured by the chamber as a dose averaged over the air cavity within the ion-chamber active volume (Dair). The absorbed dose to water (Dwater) is derived as the dose deposited inside the same volume, in the same geometrical position, filled and surrounded by water in the absence of the ion chamber. Therefore, the Dwater/Dair dose ratio is the MC estimator of the total correction factor needed to convert the absorbed dose in air into the absorbed dose in water. The dose ratio was calculated for the μIC located at the isocentre within the OARs for both clinical cases. The clinical impact of the calculated dose error was found to be negligible for the studied IMRT treatments.

Dosimetry and Image Quality in Control Studies in Computerised Tomography Realized to Paediatric Patients

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

Hernandez, M. R.; Gamboa-deBuen, I.; Dies, P.

Computerised tomography (CT) is a favourite method of medical diagnosis. Its use has thus increased rapidly throughout the world, particularly in studies relating to children. However to avoid administering unnecessarily high doses of radiation to paediatric patients it is important to have correct dose reference levels to minimize risk. The research is being developed within the public health sector at the Hospital Infantil de Mexico 'Dr. Federico Gomez.' We measured the entrance surface air kerma (K{sub P}) in paediatric patients, during the radiological studies of control in CT (studies of head, thorax and abdomen). Phantom was used to evaluate imagemore » quality as the tomograph requires a high resolution image in order to operate at its optimum level.« less

Clinical trial to evaluate safety and immunogenicity of an oral inactivated enterotoxigenic Escherichia coli prototype vaccine containing CFA/I overexpressing bacteria and recombinantly produced LTB/CTB hybrid protein.

PubMed

Lundgren, A; Leach, S; Tobias, J; Carlin, N; Gustafsson, B; Jertborn, M; Bourgeois, L; Walker, R; Holmgren, J; Svennerholm, A-M

2013-02-06

We have developed a new oral vaccine against enterotoxigenic Escherichia coli (ETEC) diarrhea containing killed recombinant E. coli bacteria expressing increased levels of ETEC colonization factors (CFs) and a recombinant protein (LCTBA), i.e. a hybrid between the binding subunits of E. coli heat labile toxin (LTB) and cholera toxin (CTB). We describe a randomized, comparator controlled, double-blind phase I trial in 60 adult Swedish volunteers of a prototype of this vaccine. The safety and immunogenicity of the prototype vaccine, containing LCTBA and an E. coli strain overexpressing the colonization factor CFA/I, was compared to a previously developed oral ETEC vaccine, consisting of CTB and inactivated wild type ETEC bacteria expressing CFA/I (reference vaccine). Groups of volunteers were given two oral doses of either the prototype or the reference vaccine; the prototype vaccine was administered at the same or a fourfold higher dosage than the reference vaccine. The prototype vaccine was found to be safe and equally well-tolerated as the reference vaccine at either dosage tested. The prototype vaccine induced mucosal IgA (fecal secretory IgA and intestine-derived IgA antibody secreting cell) responses to both LTB and CFA/I, as well as serum IgA and IgG antibody responses to LTB. Immunization with LCTBA resulted in about twofold higher mucosal and systemic IgA responses against LTB than a comparable dose of CTB. The higher dose of the prototype vaccine induced significantly higher fecal and systemic IgA responses to LTB and fecal IgA responses to CFA/I than the reference vaccine. These results demonstrate that CF over-expression and inclusion of the LCTBA hybrid protein in an oral inactivated ETEC vaccine does not change the safety profile when compared to a previous generation of such a vaccine and that the prototype vaccine induces significant dose dependent mucosal immune responses against CFA/I and LTB. Copyright © 2013 Elsevier Ltd. All rights reserved.

Development of a paediatric population-based model of the pharmacokinetics of rivaroxaban.

PubMed

Willmann, Stefan; Becker, Corina; Burghaus, Rolf; Coboeken, Katrin; Edginton, Andrea; Lippert, Jörg; Siegmund, Hans-Ulrich; Thelen, Kirstin; Mück, Wolfgang

2014-01-01

Venous thromboembolism has been increasingly recognised as a clinical problem in the paediatric population. Guideline recommendations for antithrombotic therapy in paediatric patients are based mainly on extrapolation from adult clinical trial data, owing to the limited number of clinical trials in paediatric populations. The oral, direct Factor Xa inhibitor rivaroxaban has been approved in adult patients for several thromboembolic disorders, and its well-defined pharmacokinetic and pharmacodynamic characteristics and efficacy and safety profiles in adults warrant further investigation of this agent in the paediatric population. The objective of this study was to develop and qualify a physiologically based pharmacokinetic (PBPK) model for rivaroxaban doses of 10 and 20 mg in adults and to scale this model to the paediatric population (0-18 years) to inform the dosing regimen for a clinical study of rivaroxaban in paediatric patients. Experimental data sets from phase I studies supported the development and qualification of an adult PBPK model. This adult PBPK model was then scaled to the paediatric population by including anthropometric and physiological information, age-dependent clearance and age-dependent protein binding. The pharmacokinetic properties of rivaroxaban in virtual populations of children were simulated for two body weight-related dosing regimens equivalent to 10 and 20 mg once daily in adults. The quality of the model was judged by means of a visual predictive check. Subsequently, paediatric simulations of the area under the plasma concentration-time curve (AUC), maximum (peak) plasma drug concentration (C max) and concentration in plasma after 24 h (C 24h) were compared with the adult reference simulations. Simulations for AUC, C max and C 24h throughout the investigated age range largely overlapped with values obtained for the corresponding dose in the adult reference simulation for both body weight-related dosing regimens. However, pharmacokinetic values in infants and preschool children (body weight <40 kg) were lower than the 90 % confidence interval threshold of the adult reference model and, therefore, indicated that doses in these groups may need to be increased to achieve the same plasma levels as in adults. For children with body weight between 40 and 70 kg, simulated plasma pharmacokinetic parameters (C max, C 24h and AUC) overlapped with the values obtained in the corresponding adult reference simulation, indicating that body weight-related exposure was similar between these children and adults. In adolescents of >70 kg body weight, the simulated 90 % prediction interval values of AUC and C 24h were much higher than the 90 % confidence interval of the adult reference population, owing to the weight-based simulation approach, but for these patients rivaroxaban would be administered at adult fixed doses of 10 and 20 mg. The paediatric PBPK model developed here allowed an exploratory analysis of the pharmacokinetics of rivaroxaban in children to inform the dosing regimen for a clinical study in paediatric patients.

Effect of Study Design on Sample Size in Studies Intended to Evaluate Bioequivalence of Inhaled Short-Acting β-Agonist Formulations.

PubMed

Zeng, Yaohui; Singh, Sachinkumar; Wang, Kai; Ahrens, Richard C

2018-04-01

Pharmacodynamic studies that use methacholine challenge to assess bioequivalence of generic and innovator albuterol formulations are generally designed per published Food and Drug Administration guidance, with 3 reference doses and 1 test dose (3-by-1 design). These studies are challenging and expensive to conduct, typically requiring large sample sizes. We proposed 14 modified study designs as alternatives to the Food and Drug Administration-recommended 3-by-1 design, hypothesizing that adding reference and/or test doses would reduce sample size and cost. We used Monte Carlo simulation to estimate sample size. Simulation inputs were selected based on published studies and our own experience with this type of trial. We also estimated effects of these modified study designs on study cost. Most of these altered designs reduced sample size and cost relative to the 3-by-1 design, some decreasing cost by more than 40%. The most effective single study dose to add was 180 μg of test formulation, which resulted in an estimated 30% relative cost reduction. Adding a single test dose of 90 μg was less effective, producing only a 13% cost reduction. Adding a lone reference dose of either 180, 270, or 360 μg yielded little benefit (less than 10% cost reduction), whereas adding 720 μg resulted in a 19% cost reduction. Of the 14 study design modifications we evaluated, the most effective was addition of both a 90-μg test dose and a 720-μg reference dose (42% cost reduction). Combining a 180-μg test dose and a 720-μg reference dose produced an estimated 36% cost reduction. © 2017, The Authors. The Journal of Clinical Pharmacology published by Wiley Periodicals, Inc. on behalf of American College of Clinical Pharmacology.

A dose response randomised controlled trial of docosahexaenoic acid (DHA) in preterm infants.

PubMed

Collins, C T; Sullivan, T R; McPhee, A J; Stark, M J; Makrides, M; Gibson, R A

2015-08-01

Thirty one infants born less than 30 weeks׳ gestational age were randomised to receive either 40 (n=11), 80 (n=9) or 120 (n=11) mg/kg/day of docosahexaenoic acid (DHA) respectively as an emulsion, via the feeding tube, commenced within 4 days of the first enteral feed. Twenty three infants were enroled in non-randomised reference groups; n=11 who had no supplementary DHA and n=12 who had maternal DHA supplementation. All levels of DHA in the emulsion were well tolerated with no effect on number of days of interrupted feeds or days to full enteral feeds. DHA levels in diets were directly related to blood DHA levels but were unrelated to arachidonic acid (AA) levels. All randomised groups and the maternal supplementation reference group prevented the drop in DHA levels at study end that was evident in infants not receiving supplementation. Australian New Zealand Clinical Trials Registry: ACTRN12610000382077. Copyright © 2015 Elsevier Ltd. All rights reserved.

Towards the definition of Institutional diagnostic reference levels in paediatric interventional cardiology procedures in Greece.

PubMed

Kottou, S; Kollaros, N; Plemmenos, C; Mastorakou, I; Apostolopoulou, S C; Tsapaki, V

2018-02-01

This study aimed to evaluate paediatric radiation doses in a dedicated cardiology hospital, with the objective of characterising patterns in dose variation. The ultimate purpose was to define Local (Institutional) Diagnostic Reference Levels (LDRLs) for different types of paediatric cardiac interventional procedures (IC), according to patient age. From a total of 710 cases performed during three consecutive years, by operators with more than 15 years of experience, the age was noted in only 477 IC procedures. The median values obtained for Fluoroscopy Time (FT), Number of Frames (N) and Kerma Area Product (P KA ) by age range were 5.8 min, 1322 and 2.0 Gy.cm 2 for <1 y; 6.5 min, 1403 and 3.0 Gy.cm 2 for 1 to <5 y; 5.9 min, 950 and 7.0 Gy.cm 2 for 5 to <10 y; 5.7 min, 940 and 14.0 Gy.cm 2 for 10 to <16 y, respectively. A large range of patient dose data is observed, depending greatly on procedure type and patient age. In all age groups the range of median FT, N and P KA values was 3.1-15.8 min, 579-1779 and 1.0-20.8 Gy.cm 2 respectively. Consequently, the definition of LDRLs presents challenges mainly due to the multiple clinical and technical factors affecting the outcome. On the other hand the lack of paediatric IC DRLs makes the identification of good practices more difficult. A consensus is needed on IC procedures nomenclature and grouping in order to allow a common assessment and comparison of doses. Copyright © 2018 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

TH-AB-207A-06: The Use of Realistic Phantoms to Predict CT Dose to Pediatric Patients

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

Carver, D; Kost, S; Fraser, N

Purpose: To predict pediatric patient dose from diagnostic CT scans using Monte Carlo simulation of realistic reference phantoms of various ages, weights, and heights. Methods: A series of deformable pediatric reference phantoms using Non-Uniform Rational B-Splines (NURBS) was developed for a large range of ages, percentiles, and reference anatomy. Individual bones were modeled using age-dependent factors, and red marrow was modeled as functions of age and spatial distribution based on Cristy1. Organ and effective doses for the phantom series were calculated using Monte Carlo simulation of chest, abdominopelvic, and chest-abdomen-pelvis CT exams. Non-linear regression was performed to determine the relationshipmore » between dose-length-product (DLP)-normalized organ and effective doses and phantom diameter. Patient-specific voxel computational phantoms were also created by manual segmentation of previously acquired CT images for 40 pediatric patients (0.7 to 17 years). Organ and effective doses were determined by Monte Carlo simulation of these patient-specific phantoms. Each patient was matched to the closest pediatric reference phantom based primarily on age and diameter for all major organs within the torso. Results: A total of 80 NURBS phantoms were created ranging from newborn to 15 years with height/weight percentiles from 10 to 90%. Organ and effective dose normalized by DLP correlated strongly with exponentially decreasing average phantom diameter (R{sup 2} > 0.95 for most organs). A similar relationship was determined for the patient-specific voxel phantoms. Differences between patient-phantom matched organ-dose values ranged from 0.37 to 2.39 mGy (2.87% to 22.1%). Conclusion: Dose estimation using NURBS-based pediatric reference phantoms offers the ability to predict patient dose before and after CT examinations, and physicians and scientists can use this information in their analysis of dose prescriptions for particular subjects and study types. This may lead to practices that minimize radiation dose while still achieving high quality images and, ultimately, improved patient care. NIH/NCI 1 R01 CA155400-01A1.« less

Organochlorine pesticides and polychlorinated biphenyls in fish from Lake Awassa in the Ethiopian Rift Valley: human health risks.

PubMed

Deribe, Ermias; Rosseland, Bjørn Olav; Borgstrøm, Reidar; Salbu, Brit; Gebremariam, Zinabu; Dadebo, Elias; Skipperud, Lindis; Eklo, Ole Martin

2014-08-01

Dietary intake of fish containing organic contaminants poses a potential threat to human health. In the present work, an assessment has been carried out to look at the human health risk associated with consumption of fish contaminated with organochlorine pesticides (OCPs) and polychlorinated biphenyles (PCBs) in certain fish species collected from Lake Hawassa, Ethiopia. The health risk assessment was made by comparing the concentrations of OCPs and PCBs in fish muscle tissues with reference doses given in the USEPA guidelines. Dichlorodiphenyltrichloroethanes (DDTs), endosulfans, PCBs and chloridanes were identified in fish species collected from Lake Hawassa. The most predominant pesticides were DDTs, with mean concentrations of ΣDDT ranging from 19 to 56 ng g(-1) wet weights. The highest concentrations of DDTs were found in Barbus intermedius, representing the highest trophic level. PCBs, DDT and endosulfan concentrations found in B. intermedius exceeded the reference dose for children between the ages of 0-1 year (with hazard index of above 1.0). Therefore, consumption of fish from a high trophic level (e.g. B. intermedius) from Lake Hawassa may pose a special health risk to children.

Below-Background Ionizing Radiation as an Environmental Cue for Bacteria

DOE PAGES

Castillo, Hugo; Smith, Geoffrey B.

2017-02-14

All organisms on earth grow under the influence of a natural and relatively constant dose of ionizing radiation referred to as background radiation, and so cells have different mechanisms to prevent the accumulation of damage caused by its different components. However, current knowledge of the deleterious effects of radiation on cells is based on the exposure to acute and high or to chronic, above background doses of radiation and therefore is not appropriate to explain the cellular and biochemical mechanisms that cells employ to sense and respond to chronic below-background levels. Studies at below-background radiation doses can provide insight intomore » the biological role of radiation, as suggested by several examples of what appears to be a stress response in cells grown at doses that range from 10 to 79 times lower than background. Here, we discuss some of the technical constraints to shield cells from radiation to below-background levels, as well as different approaches used to detect and measure responses to such unusual environmental conditions. Then, we present data from Shewanella oneidensis and Deinococcus radiodurans experiments that show how two taxonomically distant bacterial species sense and respond to unnaturally low levels of radiation. Finally, in brief, we grew S. oneidensis and D. radiodurans in liquid culture at dose rates of 72.05 (control) and 0.91 (treatment) nGy hr -1 (including radon) for up to 72 h and measured cell density and the expression of stress-related genes. Our results suggest that a stress response is triggered in the absence of normal levels of radiation.« less

Below-Background Ionizing Radiation as an Environmental Cue for Bacteria

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

Castillo, Hugo; Smith, Geoffrey B.

All organisms on earth grow under the influence of a natural and relatively constant dose of ionizing radiation referred to as background radiation, and so cells have different mechanisms to prevent the accumulation of damage caused by its different components. However, current knowledge of the deleterious effects of radiation on cells is based on the exposure to acute and high or to chronic, above background doses of radiation and therefore is not appropriate to explain the cellular and biochemical mechanisms that cells employ to sense and respond to chronic below-background levels. Studies at below-background radiation doses can provide insight intomore » the biological role of radiation, as suggested by several examples of what appears to be a stress response in cells grown at doses that range from 10 to 79 times lower than background. Here, we discuss some of the technical constraints to shield cells from radiation to below-background levels, as well as different approaches used to detect and measure responses to such unusual environmental conditions. Then, we present data from Shewanella oneidensis and Deinococcus radiodurans experiments that show how two taxonomically distant bacterial species sense and respond to unnaturally low levels of radiation. Finally, in brief, we grew S. oneidensis and D. radiodurans in liquid culture at dose rates of 72.05 (control) and 0.91 (treatment) nGy hr -1 (including radon) for up to 72 h and measured cell density and the expression of stress-related genes. Our results suggest that a stress response is triggered in the absence of normal levels of radiation.« less

Determination of dosimetric quantities in pediatric abdominal computed tomography scans*

PubMed Central

Jornada, Tiago da Silva; da Silva, Teógenes Augusto

2014-01-01

Objective Aiming at contributing to the knowledge on doses in computed tomography (CT), this study has the objective of determining dosimetric quantities associated with pediatric abdominal CT scans, comparing the data with diagnostic reference levels (DRL). Materials and methods The study was developed with a Toshiba Asteion single-slice CT scanner and a GE BrightSpeed multi-slice CT unit in two hospitals. Measurements were performed with a pencil-type ionization chamber and a 16 cm-diameter polymethylmethacrylate trunk phantom. Results No significant difference was observed in the values for weighted air kerma index (CW), but the differences were relevant in values for volumetric air kerma index (CVOL), air kerma-length product (PKL,CT) and effective dose. Conclusion Only the CW values were lower than the DRL, suggesting that dose optimization might not be necessary. However, PKL,CT and effective dose values stressed that there still is room for reducing pediatric radiation doses. The present study emphasizes the importance of determining all dosimetric quantities associated with CT scans. PMID:25741103

Calibration of coronary calcium scores determined using iterative image reconstruction (AIDR 3D) at 120, 100, and 80 kVp

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

Blobel, Joerg, E-mail: Joerg.Blobel@toshiba-medical.eu; Mews, Juergen; Schuijf, Joanne D.

Purpose: Computed tomography (CT) radiation dose reduction is frequently achieved by applying lower tube voltages and using iterative reconstruction (IR). For calcium scoring, the reference protocol at 120 kVp with filtered back projection (FBP) is still used, because kVp and IR may influence the Agatston score (AS) and volume score (VS). The authors present a two-step method to optimize dose: first, to determine the lowest feasible exposure and highest noise thresholds; second, to define a calibration method that ensures that the AS and VS are similar to the reference protocol. Methods: AS and VS were measured for an anthropomorphic thoracicmore » phantom that includes a calcium calibration module. The phantom was scanned on a 320-row CT scanner, at tube voltages of 120 kVp using FBP, and 120, 100, and 80 kVp using adaptive iterative dose reduction (AIDR 3D) reconstruction. The minimum CTDIs were determined based on three objective quality criteria. Calibration was performed to estimate adjusted CT number thresholds for the lower kVp acquisitions. Finally, the accuracies of the total and individual insert scores at dose level close to the minimum CTDI level were investigated and compared to low (FBP{sub LD} − 120) and high (FBP{sub HD} − 120) dose reference protocols (based on ten repeated acquisitions for each group). Results: IR allows the exposure to be reduced by 69% at 120 kVp, with no significant effect on the total scores when averaged over all included dose steps and compared to FBP-120 (AS: 693 vs 699, p = 0.182; VS: 588 vs 587 mm{sup 3}, p = 0.569). Also when averaged over ten repeated scans and compared to FBP{sub HD} − 120 (AS: 709 vs 704, p = 0.435; VS: 604 vs 601 mm{sup 3}, p = 0.479), there is no statistical significant effect. Reducing the peak tube voltage allows even greater dose reductions: 73% at 100 kVp and 76% at 80 kVp. The calibrated CT number thresholds for analysis at 120, 100, and 80 kVp were, respectively, 130, 133, and 160 HU for the Agatston score, and 130, 132, and 140 HU for the volume score. Following the calibration, the mean scores of the four groups with dose variation were not significantly different from the reference protocol, at 100 kVp (AS: 698 vs 699, p = 0.818; VS: 584 vs 587 mm{sup 3}, p = 0.365) or at 80 kVp (AS: 698 vs 699, p = 0.996; VS: 586 vs 587 mm{sup 3}, p = 0.827). Similarly, there was no significant score difference with FBP{sub LD} − 120 during repeated scanning: 100 kVp (AS: 690 vs 694, p = 0.394; VS: 579 vs 585 mm{sup 3}, p = 0.168) and 80 kVp (AS: 703 vs 694, p = 0.115; VS: 588 vs 585 mm{sup 3}, p = 0.613). Compared to FBP{sub HD} − 120 group, the relative score deviation for the accuracy of the 400 and 800 mg/cm{sup 3} HA inserts with 3 and 5 mm diameter is less than 7%. However, the relative deviation of the smaller 1 mm inserts is poorer (up to 41% deviations for scores <3). Conclusions: With iterative reconstruction using AIDR 3D, deviations of the total Agatston and volume scores remain within 4% of the reference protocol. The 1 mm inserts were detected as calcification, but scores less than ten tend to be underestimated. Following the calibration process, the application of IR in combination with reduced tube voltages allows up to 76% lower radiation dose.« less

Gamma-ray spectra and doses from the Little Boy replica

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

Moss, C.E.; Lucas, M.C.; Tisinger, E.W.

1984-01-01

Most radiation safety guidelines in the nuclear industry are based on the data concerning the survivors of the nuclear explosions at Hiroshima and Nagasaki. Crucial to determining these guidelines is the radiation from the explosions. We have measured gamma-ray pulse-height distributions from an accurate replica of the Little Boy device used at Hiroshima, operated at low power levels near critical. The device was placed outdoors on a stand 4 m from the ground to minimize environmental effects. The power levels were based on a monitor detector calibrated very carefully in independent experiments. High-resolution pulse-height distributions were acquired with a germaniummore » detector to identify the lines and to obtain line intensities. The 7631 to 7645 keV doublet from neutron capture in the heavy steel case was dominant. Low-resolution pulse-height distributions were acquired with bismuth-germanate detectors. We calculated flux spectra from these distributions using accurately measured detector response functions and efficiency curves. We then calculated dose-rate spectra from the flux spectra using a flux-to-dose-rate conversion procedure. The integral of each dose-rate spectrum gave an integral dose rate. The integral doses at 2 m ranged from 0.46 to 1.03 mrem per 10/sup 13/ fissions. The output of the Little Boy replica can be calculated with Monte Carlo codes. Comparison of our experimental spectra, line intensities, and integral doses can be used to verify these calculations at low power levels and give increased confidence to the calculated values from the explosion at Hiroshima. These calculations then can be used to establish better radiation safety guidelines. 7 references, 7 figures, 2 tables.« less

Proof of mechanism study of a novel serotonin transporter blocker, DA-8031, using [11C]DASB positron emission tomography and in vivo microdialysis.

PubMed

Park, Hyun Soo; Jung, In Soon; Lim, Nam Hee; Sung, Ji Hyun; Lee, Sukhyang; Moon, Byung Seok; Lee, Byung Chul; Kang, Kyung Koo; Kim, Sang Eun

2014-07-01

To investigate the efficacy of DA-8031, a novel compound for the treatment of premature ejaculation, we measured serotonin transporter (SERT) occupancy by DA-8031, as well as DA-8031-induced changes in extracellular serotonin levels, in the rat brain using positron emission tomography (PET) and 11C-N,N-dimethyl-2-(2-amino-4-cyanophenylthio) benzylamine ([11C]DASB) and in vivo microdialysis, respectively. [11C]DASB PET scans were performed in rats with graded doses of DA-8031 (vehicle: 10, 30, and 100 mg/kg). SERT occupancy in the midbrain was determined using binding potentials for [11C]DASB calculated by the multilinear reference tissue model. Extracellular serotonin levels were monitored in the dorsal raphe nucleus of rats after the administration of DA-8031 (10-100 mg/kg) using in vivo microdialysis. PET data indicated a reduction of [11C]DASB binding to SERTs in the midbrain as a function of DA-8031 dose. SERT occupancy for each DA-8031 dose (10-100 mg/kg) ranged between 31% and 84%. The drug dose required for 50% occupancy of SERT was 13.5 mg/kg in the midbrain, comparable with previous preclinical behavioral data (∼10-30 mg/kg). In vivo microdialysis showed that DA-8031 produced a dose-dependent increase in extracellular serotonin levels in the dorsal raphe nucleus (33%-81% increase for doses of 10-100 mg/kg). These preclinical data provide a proof of mechanism for DA-8031 as a novel compound of targeting the SERT for the treatment of premature ejaculation, warranting further clinical trials. They also offer insight into the optimal drug dose needed to exert therapeutic effects while minimizing adverse effects in humans. Copyright © 2014 Elsevier Inc. All rights reserved.

Beam hardening artifact reduction using dual energy computed tomography: implications for myocardial perfusion studies

PubMed Central

Carrascosa, Patricia; Cipriano, Silvina; De Zan, Macarena; Deviggiano, Alejandro; Capunay, Carlos; Cury, Ricardo C.

2015-01-01

Background Myocardial computed tomography perfusion (CTP) using conventional single energy (SE) imaging is influenced by the presence of beam hardening artifacts (BHA), occasionally resembling perfusion defects and commonly observed at the left ventricular posterobasal wall (PB). We therefore sought to explore the ability of dual energy (DE) CTP to attenuate the presence of BHA. Methods Consecutive patients without history of coronary artery disease who were referred for computed tomography coronary angiography (CTCA) due to atypical chest pain and a normal stress-rest SPECT and had absence or mild coronary atherosclerosis constituted the study population. The study group was acquired using DE and the control group using SE imaging. Results Demographical characteristics were similar between groups, as well as the heart rate and the effective radiation dose. Myocardial signal density (SD) levels were evaluated in 280 basal segments among the DE group (140 PB segments for each energy level from 40 to 100 keV; and 140 reference segments), and in 40 basal segments (at the same locations) among the SE group. Among the DE group, myocardial SD levels and myocardial SD ratio evaluated at the reference segment were higher at low energy levels, with significantly lower SD levels at increasing energy levels. Myocardial signal-to-noise ratio was not significantly influenced by the energy level applied, although 70 keV was identified as the energy level with the best overall signal-to-noise ratio. Significant differences were identified between the PB segment and the reference segment among the lower energy levels, whereas at ≥70 keV myocardial SD levels were similar. Compared to DE reconstructions at the best energy level (70 keV), SE acquisitions showed no significant differences overall regarding myocardial SD levels among the reference segments. Conclusions BHA that influence the assessment of myocardial perfusion can be attenuated using DE at 70 keV or higher. PMID:25774354

Assessment of dedicated low-dose cardiac micro-CT reconstruction algorithms using the left ventricular volume of small rodents as a performance measure.

PubMed

Maier, Joscha; Sawall, Stefan; Kachelrieß, Marc

2014-05-01

Phase-correlated microcomputed tomography (micro-CT) imaging plays an important role in the assessment of mouse models of cardiovascular diseases and the determination of functional parameters as the left ventricular volume. As the current gold standard, the phase-correlated Feldkamp reconstruction (PCF), shows poor performance in case of low dose scans, more sophisticated reconstruction algorithms have been proposed to enable low-dose imaging. In this study, the authors focus on the McKinnon-Bates (MKB) algorithm, the low dose phase-correlated (LDPC) reconstruction, and the high-dimensional total variation minimization reconstruction (HDTV) and investigate their potential to accurately determine the left ventricular volume at different dose levels from 50 to 500 mGy. The results were verified in phantom studies of a five-dimensional (5D) mathematical mouse phantom. Micro-CT data of eight mice, each administered with an x-ray dose of 500 mGy, were acquired, retrospectively gated for cardiac and respiratory motion and reconstructed using PCF, MKB, LDPC, and HDTV. Dose levels down to 50 mGy were simulated by using only a fraction of the projections. Contrast-to-noise ratio (CNR) was evaluated as a measure of image quality. Left ventricular volume was determined using different segmentation algorithms (Otsu, level sets, region growing). Forward projections of the 5D mouse phantom were performed to simulate a micro-CT scan. The simulated data were processed the same way as the real mouse data sets. Compared to the conventional PCF reconstruction, the MKB, LDPC, and HDTV algorithm yield images of increased quality in terms of CNR. While the MKB reconstruction only provides small improvements, a significant increase of the CNR is observed in LDPC and HDTV reconstructions. The phantom studies demonstrate that left ventricular volumes can be determined accurately at 500 mGy. For lower dose levels which were simulated for real mouse data sets, the HDTV algorithm shows the best performance. At 50 mGy, the deviation from the reference obtained at 500 mGy were less than 4%. Also the LDPC algorithm provides reasonable results with deviation less than 10% at 50 mGy while PCF and MKB reconstruction show larger deviations even at higher dose levels. LDPC and HDTV increase CNR and allow for quantitative evaluations even at dose levels as low as 50 mGy. The left ventricular volumes exemplarily illustrate that cardiac parameters can be accurately estimated at lowest dose levels if sophisticated algorithms are used. This allows to reduce dose by a factor of 10 compared to today's gold standard and opens new options for longitudinal studies of the heart.

SU-F-T-124: Radiation Biological Equivalent Presentations OfLEM-1 and MKM Approaches in the Carbon-Ion Radiotherapy

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

Hsi, W; Jiang, G; Sheng, Y

Purpose: To study the correlations of the radiation biological equivalent doses (BED) along depth and lateral distance between LEM-1 and MKM approaches. Methods: In NIRS-MKM (Microdosimetric Kinetic Model) approach, the prescribed BED, referred as C-Eq, doses aims to present the relative biological effectiveness (RBE) for different energies of carbon-ions on a fixed 10% survival value of HCG cell with respect to convention X-ray. Instead of a fixed 10% survival, the BED doses of LEM-1 (Local Effect Model) approach, referred as X-Eq, aims to present the RBE over the whole survival curve of chordoma-like cell with alpha/beta ratio of 2.0. Themore » relationship of physical doses as a function of C-Eq and X-Eq doses were investigated along depth and lateral distance for various sizes of cubic targets in water irradiated by carbon-ions. Results: At the center of each cubic target, the trends between physical and C-Eq or X-Eq doses can be described by a linear and 2nd order polynomial functions, respectively. Using fit functions can then calculate a scaling factor between C-Eq and X-Eq doses to have similar physical doses. With equalized C-Eq and X-Eq doses at the depth of target center, over- and under-estimated X-Eq to C-Eq are seen for depths before and after the target center, respectively. Near the distal edge along depth, sharp rising of RBE value is observed for X-Eq, but sharp dropping of RBE value is observed for C-Eq. For lateral locations near and just outside 50% dose level, sharp raising of RBE value is also seen for X-Eq, while only minor increasing with fast dropping for C-Eq. Conclusion: An analytical function to model the differences between the CEq and X-Eq doses along depth and lateral distance need to further investigated to explain varied clinic outcome of specific cancers using two different approaches to calculated BED doses.« less

A Preliminary Performance Assessment for Salt Disposal of High-Level Nuclear Waste - 12173

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

Lee, Joon H.; Clayton, Daniel; Jove-Colon, Carlos

2012-07-01

A salt repository is one of the four geologic media currently under study by the U.S. DOE Office of Nuclear Energy to support the development of a long-term strategy for geologic disposal of commercial used nuclear fuel (UNF) and high-level radioactive waste (HLW). The immediate goal of the generic salt repository study is to develop the necessary modeling tools to evaluate and improve the understanding of the repository system response and processes relevant to long-term disposal of UNF and HLW in a salt formation. The current phase of this study considers representative geologic settings and features adopted from previous studiesmore » for salt repository sites. For the reference scenario, the brine flow rates in the repository and underlying interbeds are very low, and transport of radionuclides in the transport pathways is dominated by diffusion and greatly retarded by sorption on the interbed filling materials. I-129 is the dominant annual dose contributor at the hypothetical accessible environment, but the calculated mean annual dose is negligibly small. For the human intrusion (or disturbed) scenario, the mean mass release rate and mean annual dose histories are very different from those for the reference scenario. Actinides including Pu-239, Pu-242 and Np-237 are major annual dose contributors, and the calculated peak mean annual dose is acceptably low. A performance assessment model for a generic salt repository has been developed incorporating, where applicable, representative geologic settings and features adopted from literature data for salt repository sites. The conceptual model and scenario for radionuclide release and transport from a salt repository were developed utilizing literature data. The salt GDS model was developed in a probabilistic analysis framework. The preliminary performance analysis for demonstration of model capability is for an isothermal condition at the ambient temperature for the near field. The capability demonstration emphasizes key attributes of a salt repository that are potentially important to the long-term safe disposal of UNF and HLW. The analysis presents and discusses the results showing repository responses to different radionuclide release scenarios (undisturbed and human intrusion). For the reference (or nominal or undisturbed) scenario, the brine flow rates in the repository and underlying interbeds are very low, and transport of radionuclides in the transport pathways is dominated by diffusion and greatly retarded by sorption on the interbed filling materials. I-129 (non-sorbing and unlimited solubility with a very long half-life) is the dominant annual dose contributor at the hypothetical accessible environment, but the calculated mean annual dose is negligibly small that there is no meaningful consequence for the repository performance. For the human intrusion (or disturbed) scenario analysis, the mean mass release rate and mean annual dose histories are very different from those for the reference scenario analysis. Compared to the reference scenario, the relative annual dose contributions by soluble, non-sorbing fission products, particularly I-129, are much lower than by actinides including Pu-239, Pu-242 and Np-237. The lower relative mean annual dose contributions by the fission product radionuclides are due to their lower total inventory available for release (i.e., up to five affected waste packages), and the higher mean annual doses by the actinides are the outcome of the direct release of the radionuclides into the overlying aquifer having high water flow rates, thereby resulting in an early arrival of higher concentrations of the radionuclides at the biosphere drinking water well prior to their significant decay. The salt GDS model analysis has also identified the following future recommendations and/or knowledge gaps to improve and enhance the confidence of the future repository performance analysis. - Repository thermal loading by UNF and HLW, and the effect on the engineered barrier and near-field performance. - Closure and consolidation of salt rocks by creep deformation under the influence of thermal perturbation, and the effect on the engineered barrier and near-field performance. - Brine migration and radionuclide transport under the influence of thermal perturbation in generic salt repository environment, and the effect on the engineered barrier and near-field performance and far-field performance. - Near-field geochemistry and radionuclide mobility in generic salt repository environment (high ionic strength brines, elevated temperatures and chemically reducing condition). - Degradation of engineer barrier components (waste package, waste canister, waste forms, etc.) in a generic salt repository environment (high ionic strength brines, elevated temperatures and chemically reducing condition). - Waste stream types and inventory estimates, particularly for reprocessing high-level waste. (authors)« less

Pharmacokinetics of concentrated naloxone nasal spray for opioid overdose reversal: Phase I healthy volunteer study.

PubMed

McDonald, Rebecca; Lorch, Ulrike; Woodward, Jo; Bosse, Björn; Dooner, Helen; Mundin, Gill; Smith, Kevin; Strang, John

2018-03-01

Take-home naloxone can prevent death from heroin/opioid overdose, but pre-provision is difficult because naloxone is usually given by injection. Non-injectable alternatives, including naloxone nasal sprays, are currently being developed. To be effective, the intranasal (i.n.) spray dose must be adequate but not excessive, and early absorption must be comparable to intramuscular (i.m.) injection. We report on the pharmacokinetics (PK) of a specially produced concentrated novel nasal spray. The specific aims were to: (1) estimate PK profiles of i.n. naloxone, (2) compare early systemic exposure with i.n. versus i.m. naloxone and (3) estimate i.n. bioavailability. Open-label, randomized, five-way cross-over PK study. Clinical trials facility (Croydon, UK). Thirty-eight healthy volunteers (age 20-54 years; 11 female). Three doses of i.n. (1 mg/0.1 ml, 2 mg/0.1 ml, 4 mg/0.2 ml) versus 0.4 mg i.m. (reference) and 0.4 mg intravenous (i.v.) naloxone. Regular blood samples were taken, with high-frequency sampling during the first 15 minutes to capture early systemic exposure. PK parameters were determined from plasma naloxone concentrations. Exploratory analyses involved simulation of repeat administration. Mean peak concentration (C max ) values for 1 mg (1.51 ng/ml), 2 mg (2.87 ng/ml) and 4 mg (6.02 ng/ml) i.n. exceeded 0.4 mg i.m. (1.27 ng/ml) naloxone. All three i.n. doses rapidly achieved plasma levels > 50% of peak concentrations (T50%) by 10 minutes, peaking at 15-30 minutes (T max ). For comparison, the i.m. reference reached T max at 10 minutes. Mean bioavailability was 47-51% for i.n. relative to i.m. naloxone. Simulation of repeat dosing (2 × 2 mg i.n. versus 5 × 0.4 mg i.m. doses) at 3-minute intervals showed that comparable plasma naloxone concentrations would be anticipated. Concentrated 2 mg intranasal naloxone is well-absorbed and provides early exposure comparable to 0.4 mg intramuscular naloxone, following the 0.4 mg intramuscular curve closely in the first 10 minutes post-dosing and maintaining blood levels above twice the intramuscular reference for the next 2 hours. © 2017 The Authors. Addiction published by John Wiley & Sons Ltd on behalf of Society for the Study of Addiction.

The assessment of ionising radiation impact on the cooling pond freshwater ecosystem non-human biota from the Ignalina NPP operation beginning to shut down and initial decommissioning.

PubMed

Mazeika, J; Marciulioniene, D; Nedveckaite, T; Jefanova, O

2016-01-01

The radiological doses to non-human biota of freshwater ecosystem in the Ignalina NPP cooling pond - Lake Druksiai were evaluated for several cases including the plant's operation period and initial decommissioning activities, using the ERICA 1.2 code with IAEA SRS-19 models integrated approach and tool. Among the Lake Druksiai freshwater ecosystem reference organisms investigated the highest exposure dose rate was determined for bottom fauna - benthic organisms (mollusc-bivalves, crustaceans, mollusc-gastropods, insect larvae), and among the other reference organisms - for vascular plants. The mean and maximum total dose rate values due to anthropogenic radionuclide ionising radiation impact in all investigated cases were lower than the ERICA screening dose rate value of 10 μGy/h. The main exposure of reference organisms as a result of Ignalina NPP former effluent to Lake Druksiai is due to ionizing radiation of radionuclides (60)Co and (137)Cs, of predicted releases to Lake Druksiai during initial decommissioning period - due to radionuclides (60)Co, (134)Cs and (137)Cs, and as a result of predicted releases to Lake Druksiai from low- and intermediate-level short-lived radioactive waste disposal site in 30-100 year period - due to radionuclides (99)Tc and (3)H. The risk quotient expected values in all investigated cases were <1, and therefore the risk to non-human biota can be considered negligible with the exception of a conservative risk quotient for insect larvae. Radiological protection of non-human biota in Lake Druksiai, the Ignalina NPP cooling pond, is both feasible and acceptable. Copyright © 2015 Elsevier Ltd. All rights reserved.

Diagnostic reference level: an important tool for reducing radiation doses in adult and pediatric nuclear medicine procedures in Brazil.

PubMed

Willegaignon, José; Braga, Luis F E F; Sapienza, Marcelo T; Coura-Filho, George B; Cardona, Marissa A R; Alves, Carlos E R; Gutterres, Ricardo F; Buchpiguel, Carlos A

2016-05-01

This study aimed to establish a concise method for determining a diagnostic reference level (DRL) for adult and pediatric nuclear medicine patients on the basis of diagnostic procedures and administered radioisotope as a means of controlling medical exposure. A screening was carried out in all Brazilian Nuclear Medicine Service (NMS) establishments to support this study by collecting the average activities administered during adult diagnostic procedures and the rules applied to adjust these according to the patient's age and body mass. Percentile 75 was used in all the activities administered as a means of establishing DRL for adult patients, with additional correction factors for pediatric patients. Radiation doses from nuclear medicine procedures on the basis of average administered activity were calculated for all diagnostic exams. A total of 107 NMSs in Brazil agreed to participate in the project. From the 64 nuclear medicine procedures studied, bone, kidney, and parathyroid scans were found to be used in more than 85% of all the NMSs analyzed. There was a large disparity among the activities administered, when applying the same procedures, this reaching, in some cases, more than 20 times between the lowest and the highest. Diagnostic exams based on Ga, Tl, and I radioisotopes proved to be the major exams administering radiation doses to patients. On introducing the DRL concept into clinical routine, the minimum reduction in radiation doses received by patients was about 15%, the maximum was 95%, and the average was 50% compared with the previously reported administered activities. Variability in the available diagnostic procedures as well as in the amount of activities administered within the same procedure was appreciable not only in Brazil, but worldwide. Global efforts are needed to establish a concise DRL that can be applied in adult and pediatric nuclear medicine procedures as the application of DRL in clinical routine has been proven to be an important tool for controlling and reducing radiation doses received by patients in medical exposure.

Pediatric patient and staff dose measurements in barium meal fluoroscopic procedures

NASA Astrophysics Data System (ADS)

Filipov, D.; Schelin, H. R.; Denyak, V.; Paschuk, S. A.; Porto, L. E.; Ledesma, J. A.; Nascimento, E. X.; Legnani, A.; Andrade, M. E. A.; Khoury, H. J.

2015-11-01

This study investigates patient and staff dose measurements in pediatric barium meal series fluoroscopic procedures. It aims to analyze radiographic techniques, measure the air kerma-area product (PKA), and estimate the staff's eye lens, thyroid and hands equivalent doses. The procedures of 41 patients were studied, and PKA values were calculated using LiF:Mg,Ti thermoluminescent dosimeters (TLDs) positioned at the center of the patient's upper chest. Furthermore, LiF:Mg,Cu,P TLDs were used to estimate the equivalent doses. The results showed a discrepancy in the radiographic techniques when compared to the European Commission recommendations. Half of the results of the analyzed literature presented lower PKA and dose reference level values than the present study. The staff's equivalent doses strongly depends on the distance from the beam. A 55-cm distance can be considered satisfactory. However, a distance decrease of ~20% leads to, at least, two times higher equivalent doses. For eye lenses this dose is significantly greater than the annual limit set by the International Commission on Radiological Protection. In addition, the occupational doses were found to be much higher than in the literature. Changing the used radiographic techniques to the ones recommended by the European Communities, it is expected to achieve lower PKA values ​​and occupational doses.

Imaging the Parasinus Region with a Third-Generation Dual-Source CT and the Effect of Tin Filtration on Image Quality and Radiation Dose.

PubMed

Lell, M M; May, M S; Brand, M; Eller, A; Buder, T; Hofmann, E; Uder, M; Wuest, W

2015-07-01

CT is the imaging technique of choice in the evaluation of midface trauma or inflammatory disease. We performed a systematic evaluation of scan protocols to optimize image quality and radiation exposure on third-generation dual-source CT. CT protocols with different tube voltage (70-150 kV), current (25-300 reference mAs), prefiltration, pitch value, and rotation time were systematically evaluated. All images were reconstructed with iterative reconstruction (Advanced Modeled Iterative Reconstruction, level 2). To individually compare results with otherwise identical factors, we obtained all scans on a frozen human head. Conebeam CT was performed for image quality and dose comparison with multidetector row CT. Delineation of important anatomic structures and incidental pathologic conditions in the cadaver head was evaluated. One hundred kilovolts with tin prefiltration demonstrated the best compromise between dose and image quality. The most dose-effective combination for trauma imaging was Sn100 kV/250 mAs (volume CT dose index, 2.02 mGy), and for preoperative sinus surgery planning, Sn100 kV/150 mAs (volume CT dose index, 1.22 mGy). "Sn" indicates an additional prefiltration of the x-ray beam with a tin filter to constrict the energy spectrum. Exclusion of sinonasal disease was possible with even a lower dose by using Sn100 kV/25 mAs (volume CT dose index, 0.2 mGy). High image quality at very low dose levels can be achieved by using a Sn100-kV protocol with iterative reconstruction. The effective dose is comparable with that of conventional radiography, and the high image quality at even lower radiation exposure favors multidetector row CT over conebeam CT. © 2015 by American Journal of Neuroradiology.

Multidisciplinary European Low Dose Initiative (MELODI): strategic research agenda for low dose radiation risk research.

PubMed

Kreuzer, M; Auvinen, A; Cardis, E; Durante, M; Harms-Ringdahl, M; Jourdain, J R; Madas, B G; Ottolenghi, A; Pazzaglia, S; Prise, K M; Quintens, R; Sabatier, L; Bouffler, S

2018-03-01

MELODI (Multidisciplinary European Low Dose Initiative) is a European radiation protection research platform with focus on research on health risks after exposure to low-dose ionising radiation. It was founded in 2010 and currently includes 44 members from 18 countries. A major activity of MELODI is the continuous development of a long-term European Strategic Research Agenda (SRA) on low-dose risk for radiation protection. The SRA is intended to identify priorities for national and European radiation protection research programs as a basis for the preparation of competitive calls at the European level. Among those key priorities is the improvement of health risk estimates for exposures close to the dose limits for workers and to reference levels for the population in emergency situations. Another activity of MELODI is to ensure the availability of European key infrastructures for research activities, and the long-term maintenance of competences in radiation research via an integrated European approach for training and education. The MELODI SRA identifies three key research topics in low dose or low dose-rate radiation risk research: (1) dose and dose rate dependence of cancer risk, (2) radiation-induced non-cancer effects and (3) individual radiation sensitivity. The research required to improve the evidence base for each of the three key topics relates to three research lines: (1) research to improve understanding of the mechanisms contributing to radiogenic diseases, (2) epidemiological research to improve health risk evaluation of radiation exposure and (3) research to address the effects and risks associated with internal exposures, differing radiation qualities and inhomogeneous exposures. The full SRA and associated documents can be downloaded from the MELODI website ( http://www.melodi-online.eu/sra.html ).

Methylmercury in dried shark fins and shark fin soup from American restaurants.

PubMed

Nalluri, Deepthi; Baumann, Zofia; Abercrombie, Debra L; Chapman, Demian D; Hammerschmidt, Chad R; Fisher, Nicholas S

2014-10-15

Consumption of meat from large predatory sharks exposes human consumers to high levels of toxic monomethylmercury (MMHg). There also have been claims that shark fins, and hence the Asian delicacy shark fin soup, contain harmful levels of neurotoxic chemicals in combination with MMHg, although concentrations of MMHg in shark fins are unknown. We measured MMHg in dried, unprocessed fins (n=50) of 13 shark species that occur in the international trade of dried shark fins as well as 50 samples of shark fin soup prepared by restaurants from around the United States. Concentrations of MMHg in fins ranged from 9 to 1720 ng/g dry wt. MMHg in shark fin soup ranged from <0.01 to 34 ng/mL, with MMHg averaging 62 ± 7% of total Hg. The highest concentrations of MMHg and total Hg were observed in both fins and soup from large, high trophic level sharks such as hammerheads (Sphyrna spp.). Consumption of a 240 mL bowl of shark fin soup containing the average concentration of MMHg (4.6 ng/mL) would result in a dose of 1.1 μg MMHg, which is 16% of the U.S. EPA's reference dose (0.1 μg MMHg per 1 kg per day in adults) of 7.4 μg per day for a 74 kg person. If consumed, the soup containing the highest measured MMHg concentration would exceed the reference dose by 17%. While shark fin soup represents a potentially important source of MMHg to human consumers, other seafood products, particularly the flesh of apex marine predators, contain much higher MMHg concentrations and can result in substantially greater exposures of this contaminant for people. Copyright © 2014 Elsevier B.V. All rights reserved.

High-dose calcium stimulation test in a case of insulinoma masquerading as hysteria.

PubMed

Nakamura, Yoshio; Doi, Ryuichiro; Kohno, Yasuhiro; Shimono, Dai; Kuwamura, Naomitsu; Inoue, Koichi; Koshiyama, Hiroyuki; Imamura, Masayuki

2002-11-01

It is reported that some cases with insulinoma present with neuropsychiatric symptoms and are often misdiagnosed as psychosis. Here we report a case of insulinoma masquerading as hysteria, whose final diagnosis could be made using high-dose calcium stimulation test. A 28-yr-old woman was referred presenting with substupor, mutism, mannerism, restlessness, and incoherence. Laboratory examinations revealed hypoglycemia (33 mg/dL) and detectable insulin levels (9.7 microU/mL), suggesting the diagnosis of insulinoma. However, neither imaging studies nor selective arterial calcium injection (SACI) test with a conventional dose of calcium (0.025 mEq/kg) indicated the tumor. High-dose calcium injection (0.05 mEq/kg) evoked insulin secretion when injected into superior mesenteric artery. A solitary tumor in the head of the pancreas was resected, and her plasma glucose returned to normal. Postoperatively, iv injection of secretin resulted in a normal response of insulin, which was not found preoperatively. This case suggests the usefulness of the SACI test with high-dose of calcium in the case of insulinoma when the standard dose fails to detect such a tumor.

Reference dosimetry of proton pencil beams based on dose-area product: a proof of concept.

PubMed

Gomà, Carles; Safai, Sairos; Vörös, Sándor

2017-06-21

This paper describes a novel approach to the reference dosimetry of proton pencil beams based on dose-area product ([Formula: see text]). It depicts the calibration of a large-diameter plane-parallel ionization chamber in terms of dose-area product in a 60 Co beam, the Monte Carlo calculation of beam quality correction factors-in terms of dose-area product-in proton beams, the Monte Carlo calculation of nuclear halo correction factors, and the experimental determination of [Formula: see text] of a single proton pencil beam. This new approach to reference dosimetry proves to be feasible, as it yields [Formula: see text] values in agreement with the standard and well-established approach of determining the absorbed dose to water at the centre of a broad homogeneous field generated by the superposition of regularly-spaced proton pencil beams.

Measuring dose from radiotherapy treatments in the vicinity of a cardiac pacemaker.

PubMed

Peet, Samuel C; Wilks, Rachael; Kairn, Tanya; Crowe, Scott B

2016-12-01

This study investigated the dose absorbed by tissues surrounding artificial cardiac pacemakers during external beam radiotherapy procedures. The usefulness of out-of-field reference data, treatment planning systems, and skin dose measurements to estimate the dose in the vicinity of a pacemaker was also examined. Measurements were performed by installing a pacemaker onto an anthropomorphic phantom, and using radiochromic film and optically stimulated luminescence dosimeters to measure the dose in the vicinity of the device during the delivery of square fields and clinical treatment plans. It was found that the dose delivered in the vicinity of the cardiac device was unevenly distributed both laterally and anteroposteriorly. As the device was moved distally from the square field, the dose dropped exponentially, in line with out-of-field reference data in the literature. Treatment planning systems were found to substantially underestimate the dose for volumetric modulated arc therapy, helical tomotherapy, and 3D conformal treatments. The skin dose was observed to be either greater or lesser than the dose received at the depth of the device, depending on the treatment site, and so care should be if skin dose measurements are to be used to estimate the dose to a pacemaker. Square field reference data may be used as an upper estimate of absorbed dose per monitor unit in the vicinity of a cardiac device for complex treatments involving multiple gantry angles. Copyright © 2016 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

Comparison of exposure assessment methods in a lung cancer case-control study: performance of a lifelong task-based questionnaire for asbestos and PAHs.

PubMed

Bourgkard, Eve; Wild, Pascal; Gonzalez, Maria; Févotte, Joëlle; Penven, Emmanuelle; Paris, Christophe

2013-12-01

To describe the performance of a lifelong task-based questionnaire (TBQ) in estimating exposures compared with other approaches in the context of a case-control study. A sample of 93 subjects was randomly selected from a lung cancer case-control study corresponding to 497 jobs. For each job, exposure assessments for asbestos and polycyclic aromatic hydrocarbons (PAHs) were obtained by expertise (TBQ expertise) and by algorithm using the TBQ (TBQ algorithm) as well as by expert appraisals based on all available occupational data (REFERENCE expertise) considered to be the gold standard. Additionally, a Job Exposure Matrix (JEM)-based evaluation for asbestos was also obtained. On the 497 jobs, the various evaluations were contrasted using Cohen's κ coefficient of agreement. Additionally, on the total case-control population, the asbestos dose-response relationship based on the TBQ algorithm was compared with the JEM-based assessment. Regarding asbestos, the TBQ-exposure estimates agreed well with the REFERENCE estimate (TBQ expertise: level-weighted κ (lwk)=0.68; TBQ algorithm: lwk=0.61) but less so with the JEM estimate (TBQ expertise: lwk=0.31; TBQ algorithm: lwk=0.26). Regarding PAHs, the agreements between REFERENCE expertise and TBQ were less good (TBQ expertise: lwk=0.43; TBQ algorithm: lwk=0.36). In the case-control study analysis, the dose-response relationship between lung cancer and cumulative asbestos based on the JEM is less steep than with the TBQ-algorithm exposure assessment and statistically non-significant. Asbestos-exposure estimates based on the TBQ were consistent with the REFERENCE expertise and yielded a steeper dose-response relationship than the JEM. For PAHs, results were less clear.

TU-EF-204-08: Dose Efficiency of Added Beam-Shaping Filter with Varied Attenuation Levels in Lung-Cancer Screening CT

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

Ma, C; Yu, L; Vrieze, T

Purpose: Added filtration such as tin filter has the potential to improve dose efficiency of x-ray beam in lung-cancer screening CT. However, dose efficiency with added beam filtration is highly dependent on patient attenuation level. In this phantom study, we evaluated the image quality at different tube voltages with and without added tin filter when attenuation level varies. Methods: A 30 x 20 cm anthropomorphic thorax phantom with three added extension rings were used to simulate small (S), medium (M), large (L), and extra-large (XL) adult patients. These phantoms were scanned on a 192-slice CT scanner (Force, Siemens) at 100more » and 120kV without tin filtration, and 100 and 150 kV with tin filtration (100Sn and 150Sn), at multiple dose levels at each kV. Images were reconstructed using iterative reconstruction (ADMIRE, Siemens). Radiation dose was measured with a 0.6 cc ion chamber in the middle and peripheral areas of the phantom. Image quality was assessed using mean image noise at uniform areas in the central region and lung. Radiation dose that is required for each kV to match the noise in a routine lung-cancer CT screening technique (120kV, 25 quality reference mAs) was calculated. Results: At each of the four phantom sizes, 100Sn had the lowest noise in both soft tissue and lung. Compared with 120 kV, 100Sn saved 39%–60% dose for the same noise, depending on phantom size. For the XL phantom (50 by 40 cm), 150Sn provided images with the least beam-hardening artifact in peripheral region. Conclusion: For thoracic CT, added tin filtration can provide considerable dose reduction compared with 120 kV. 100Sn provides better dose efficiencies for all phantom sizes, while 150Sn provides better image quality in peripheral region for extra-large patients. Drs.Joel G. Fletcher and Cynthia H. McCollough receive research support from Siemens Healthcare.« less

[Association between urinary polycyclic aromatic hydrocarbon metabolites and elevated serum uric acid levels in coke oven workers].

PubMed

Deng, Siyun; Deng, Qifei; Hu, Die; Li, Jun; Zhu, Xiaoyan; Guo, Huan; Wu, Tangchun

2014-06-01

To analyze the relationship between metabolites of polycyclic aromatic hydrocarbons (PAHs) and serum uric acid levels in coke oven workers and to provide new clues to the pathogenic mechanism of PAHs. A total of 1302 coke oven workers were divided into four groups, namely control group and low-, intermediate-, and high-dose exposure groups. The concentrations of ambient PAHs at each workplace were determined by high-performance liquid chromatography. The detailed information on the occupational history and health of workers was collected by questionnaire survey and physical examination, and so were their blood and urine samples. Serum uric acid and creatinine levels were measured using a Hitachi 7020 automatic biochemical analyzer. Ten urinary PAH metabolites were detected by gas chromatography-mass spectrometry. Serum uric acid levels were the highest in the high-dose exposure group, followed by the intermediate- and low-dose exposure groups, and were the lowest in the control group. There were significant correlations between serum uric acid levels and the quartiles of 1-hydroxynaphthalene and 1-hydroxyphenanthrene (P < 0.05). After adjustment for PAH metabolite-related relationship, only urinary 1-hydroxyphenanthrene was significantly correlated with serum uric acid levels (P = 0.001). After adjustment for confounding factors and using the 1st quartile of 1-hydroxyphenanthrene as a reference, the odds ratio for hyperuricemia in subjects with the 2nd, 3rd, and 4th quartiles of 1-hydroxyphenanthrene were 1.55, 1.57, and 2.35, respectively. Urinary 1-hydroxyphenanthrene is associated with a dose-response increase in serum uric acid levels in coke oven workers, and exposure to phenanthrene in PAHs may be a risk factor for hyperuricemia.

A 2D ion chamber array audit of wedged and asymmetric fields in an inhomogeneous lung phantom.

PubMed

Lye, Jessica; Kenny, John; Lehmann, Joerg; Dunn, Leon; Kron, Tomas; Alves, Andrew; Cole, Andrew; Williams, Ivan

2014-10-01

The Australian Clinical Dosimetry Service (ACDS) has implemented a new method of a nonreference condition Level II type dosimetric audit of radiotherapy services to increase measurement accuracy and patient safety within Australia. The aim of this work is to describe the methodology, tolerances, and outcomes from the new audit. The ACDS Level II audit measures the dose delivered in 2D planes using an ionization chamber based array positioned at multiple depths. Measurements are made in rectilinear homogeneous and inhomogeneous phantoms composed of slabs of solid water and lung. Computer generated computed tomography data sets of the rectilinear phantoms are supplied to the facility prior to audit for planning of a range of cases including reference fields, asymmetric fields, and wedged fields. The audit assesses 3D planning with 6 MV photons with a static (zero degree) gantry. Scoring is performed using local dose differences between the planned and measured dose within 80% of the field width. The overall audit result is determined by the maximum dose difference over all scoring points, cases, and planes. Pass (Optimal Level) is defined as maximum dose difference ≤3.3%, Pass (Action Level) is ≤5.0%, and Fail (Out of Tolerance) is >5.0%. At close of 2013, the ACDS had performed 24 Level II audits. 63% of the audits passed, 33% failed, and the remaining audit was not assessable. Of the 15 audits that passed, 3 were at Pass (Action Level). The high fail rate is largely due to a systemic issue with modeling asymmetric 60° wedges which caused a delivered overdose of 5%-8%. The ACDS has implemented a nonreference condition Level II type audit, based on ion chamber 2D array measurements in an inhomogeneous slab phantom. The powerful diagnostic ability of this audit has allowed the ACDS to rigorously test the treatment planning systems implemented in Australian radiotherapy facilities. Recommendations from audits have led to facilities modifying clinical practice and changing planning protocols.

Impact of missing attenuation and scatter corrections on 99m Tc-MAA SPECT 3D dosimetry for liver radioembolization using the patient relative calibration methodology: A retrospective investigation on clinical images.

PubMed

Botta, Francesca; Ferrari, Mahila; Chiesa, Carlo; Vitali, Sara; Guerriero, Francesco; Nile, Maria Chiara De; Mira, Marta; Lorenzon, Leda; Pacilio, Massimiliano; Cremonesi, Marta

2018-04-01

To investigate the clinical implication of performing pre-treatment dosimetry for 90 Y-microspheres liver radioembolization on 99m Tc-MAA SPECT images reconstructed without attenuation or scatter correction and quantified with the patient relative calibration methodology. Twenty-five patients treated with SIR-Spheres ® at Istituto Europeo di Oncologia and 31 patients treated with TheraSphere ® at Istituto Nazionale Tumori were considered. For each acquired 99m Tc-MAA SPECT, four reconstructions were performed: with attenuation and scatter correction (AC_SC), only attenuation (AC_NoSC), only scatter (NoAC_SC) and without corrections (NoAC_NoSC). Absorbed dose maps were calculated from the activity maps, quantified applying the patient relative calibration to the SPECT images. Whole Liver (WL) and Tumor (T) regions were drawn on CT images. Injected Liver (IL) region was defined including the voxels receiving absorbed dose >3.8 Gy/GBq. Whole Healthy Liver (WHL) and Healthy Injected Liver (HIL) regions were obtained as WHL = WL - T and HIL = IL - T. Average absorbed dose to WHL and HIL were calculated, and the injection activity was derived following each Institute's procedure. The values obtained from AC_NoSC, NoAC_SC and NoAC_NoSC images were compared to the reference value suggested by AC_SC images using Bland-Altman analysis and Wilcoxon paired test (5% significance threshold). Absorbed-dose maps were compared to the reference map (AC_SC) in global terms using the Voxel Normalized Mean Square Error (%VNMSE), and at voxel level by calculating for each voxel the normalized difference with the reference value. The uncertainty affecting absorbed dose at voxel level was accounted for in the comparison; to this purpose, the voxel counts fluctuation due to Poisson and reconstruction noise was estimated from SPECT images of a water phantom acquired and reconstructed as patient images. NoAC_SC images lead to activity prescriptions not significantly different from the reference AC_SC images; the individual differences (<0.1 GBq for all IEO patients, <0.6 GBq for all but one INT patients) were comparable to the uncertainty affecting activity measurement. AC_NoSC and NoAC_NoSC images, instead, yielded significantly different activity prescriptions and wider 95% confidence intervals in the Bland-Altman analysis. Concerning the absorbed dose map, AC_NoSC images had the smallest %VNMSE value and the highest fraction of voxels differing less than 2 standard deviations from AC_SC. The patient relative calibration methodology can compensate for the missing attenuation correction when performing healthy liver pre-treatment dosimetry: safe treatments can be planned even on NoAC_SC images, suggesting activities comparable to AC_SC images. Scatter correction is recommended due to its heavy impact on healthy liver dosimetry. © 2018 American Association of Physicists in Medicine.

CT-image-based conformal brachytherapy of breast cancer. The significance of semi-3-D and 3-D treatment planning.

PubMed

Polgár, C; Major, T; Somogyi, A; Takácsi-Nagy, Z; Mangel, L C; Forrai, G; Sulyok, Z; Fodor, J; Németh, G

2000-03-01

To compare the conventional 2-D, the simulator-guided semi-3-D and the recently developed CT-guided 3-D brachytherapy treatment planning in the interstitial radiotherapy of breast cancer. In 103 patients with T1-2, N0-1 breast cancer the tumor bed was clipped during breast conserving surgery. Fifty-two of them received boost brachytherapy after 46 to 50 Gy teletherapy and 51 patients were treated with brachytherapy alone via flexible implant tubes. Single, double and triple plane implant was used in 6, 89 and 8 cases, respectively. The dose of boost brachytherapy and sole brachytherapy prescribed to dose reference points was 3 times 4.75 Gy and 7 times 5.2 Gy, respectively. The positions of dose reference points varied according to the level (2-D, semi-3-D and 3-D) of treatment planning performed. The treatment planning was based on the 3-D reconstruction of the surgical clips, implant tubes and skin points. In all cases the implantations were planned with a semi-3-D technique aided by simulator. In 10 cases a recently developed CT-guided 3-D planning system was used. The semi-3-D and 3-D treatment plans were compared to hypothetical 2-D plans using dose-volume histograms and dose non-uniformity ratios. The values of mean central dose, mean skin dose, minimal clip dose, proportion of underdosaged clips and mean target surface dose were evaluated. The accuracy of tumor bed localization and the conformity of planning target volume and treated volume were also analyzed in each technique. With the help of conformal semi-3-D and 3-D brachytherapy planning we could define reference dose points, active source positions and dwell times individually. This technique decreased the mean skin dose with 22.2% and reduced the possibility of geographical miss. We could achieve the best conformity between the planning target volume and the treated volume with the CT-image based 3-D treatment planning, at the cost of worse dose homogeneity. The mean treated volume was reduced by 25.1% with semi-3-D planning, however, it was increased by 16.2% with 3-D planning, compared to the 2-D planning. The application of clips into the tumor bed and the conformal (semi-3-D and 3-D) planning help to avoid geographical miss. CT is suitable for 3-D brachytherapy planning. Better local control with less side effects might be achieved with these new techniques. Conformal 3-D brachytherapy calls for new treatment planning concepts, taking the irregular 3-D shape of the target volume into account. The routine clinical application of image-based 3-D brachytherapy is a real aim in the very close future.

SU-E-P-11: Comparison of Image Quality and Radiation Dose Between Different Scanner System in Routine Abdomen CT

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

Liao, S; Wang, Y; Weng, H

Purpose To evaluate image quality and radiation dose of routine abdomen computed tomography exam with the automatic current modulation technique (ATCM) performed in two different brand 64-slice CT scanners in our site. Materials and Methods A retrospective review of routine abdomen CT exam performed with two scanners; scanner A and scanner B in our site. To calculate standard deviation of the portal hepatic level with a region of interest of 12.5 mm x 12.5mm represented to the image noise. The radiation dose was obtained from CT DICOM image information. Using Computed tomography dose index volume (CTDIv) to represented CT radiationmore » dose. The patient data in this study were with normal weight (about 65–75 Kg). Results The standard deviation of Scanner A was smaller than scanner B, the scanner A might with better image quality than scanner B. On the other hand, the radiation dose of scanner A was higher than scanner B(about higher 50–60%) with ATCM. Both of them, the radiation dose was under diagnostic reference level. Conclusion The ATCM systems in modern CT scanners can contribute a significant reduction in radiation dose to the patient. But the reduction by ATCM systems from different CT scanner manufacturers has slightly variation. Whatever CT scanner we use, it is necessary to find the acceptable threshold of image quality with the minimum possible radiation exposure to the patient in agreement with the ALARA principle.« less

Thyroid function tests in patients taking thyroid medication in Germany: Results from the population-based Study of Health in Pomerania (SHIP).

PubMed

Hannemann, Anke; Friedrich, Nele; Haring, Robin; Krebs, Alexander; Völzke, Henry; Alte, Dietrich; Nauck, Matthias; Kohlmann, Thomas; Schober, Hans-Christof; Hoffmann, Wolfgang; Wallaschofski, Henri

2010-08-16

Studies from iodine-sufficient areas have shown that a high proportion of patients taking medication for thyroid diseases have thyroid stimulating hormone (TSH) levels outside the reference range. Next to patient compliance, inadequate dosing adjustment resulting in under- and over-treatment of thyroid disease is a major cause of poor therapy outcomes. Using thyroid function tests, we aim to measure the proportions of subjects, who are under- or over-treated with thyroid medication in a previously iodine-deficient area. Data from 266 subjects participating in the population-based Study of Health in Pomerania (SHIP) were analysed. All subjects were taking thyroid medication. Serum TSH levels were measured using immunochemiluminescent procedures. TSH levels of < 0.27 or > 2.15 mIU/L in subjects younger than 50 years and < 0.19 or > 2.09 mIU/L in subjects 50 years and older, were defined as decreased or elevated, according to the established reference range for the specific study area. Our analysis revealed that 56 of 190 (29.5%) subjects treated with thyroxine had TSH levels outside the reference range (10.0% elevated, 19.5% decreased). Of the 31 subjects taking antithyroid drugs, 12 (38.7%) had TSH levels outside the reference range (9.7% elevated, 29.0% decreased). These proportions were lower in the 45 subjects receiving iodine supplementation (2.2% elevated, 8.9% decreased). Among the 3,974 SHIP participants not taking thyroid medication, TSH levels outside the reference range (2.8% elevated, 5.9% decreased) were less frequent. In concordance with previous studies in iodine-sufficient areas, our results indicate that a considerable number of patients taking thyroid medication are either under- or over-treated. Improved monitoring of these patients' TSH levels, compared to the local reference range, is recommended.

Bioequivalence of fixed-dose combination RIN®-150 to each reference drug in loose combination.

PubMed

Wang, H F; Wang, R; O'Gorman, M; Crownover, P; Damle, B

2015-03-01

RIN(®)-150 is a fixed-dose combination (FDC) tablet containing rifampicin (RMP, 150 mg) and isoniazid (INH, 75 mg) developed for the treatment of tuberculosis. This study was conducted at a single center: the Pfizer Clinical Research Unit in Singapore. To demonstrate bioequivalence of each drug component between RIN-150 and individual products in a loose combination. This was a randomized, open-label, single-dose, two-way crossover study. Subjects received single doses of RIN-150 or two individual reference products under fasting conditions in a crossover fashion, with at least 7 days washout between doses. The primary measures for comparison were peak plasma concentration (Cmax) and the area under plasma concentration-time curve (AUC). Of 28 subjects enrolled, 26 completed the study. The adjusted geometric mean ratios of Cmax and AUClast between the FDC and single-drug references and 90% confidence intervals were respectively 91.63% (90%CI 83.13-101.01) and 95.45% (90%CI 92.07-98.94) for RMP, and 107.58% (90%CI 96.07-120.47) and 103.45% (90%CI 99.33-107.75) for INH. Both formulations were generally well tolerated in this study. The RIN-150 FDC tablet formulation is bioequivalent to the two single-drug references for RMP and INH at equivalent doses.

A randomized, crossover pharmacokinetic study comparing generic tacrolimus vs. the reference formulation in subpopulations of kidney transplant patients.

PubMed

Bloom, R D; Trofe-Clark, J; Wiland, A; Alloway, R R

2013-01-01

An exploratory, post hoc analysis was performed using data from a prospective, multicenter, open-label, randomized, two-period (14 d per period), two-sequence, crossover, steady-state pharmacokinetic study comparing generic tacrolimus (Sandoz) vs. reference tacrolimus in stable renal transplant patients receiving their pre-study twice-daily dose. Pharmacokinetic parameters were compared in 68 patients according to gender, African American ethnicity, the presence or absence of diabetes, and use of steroids. The ratios of tacrolimus AUC0-12 h , Cmax , and C12 with generic vs. reference tacrolimus were calculated using the geometric mean (GM) of dose-normalized values at days 14 and 28. Mean (SD) tacrolimus dose at baseline was 5.7 (4.2) mg/d. There were no consistent differences in dose-normalized AUC0-12 h , C12 , Cmax, or tmax between the generic and reference preparations within subpopulations. The 90% confidence intervals (CI) for the ratios of dose-normalized AUC0-12 h and C12 with generic vs. reference tacrolimus were within 80-125% for all subpopulations, as were 90% CIs for Cmax other than for females, African Americans, and non-diabetics, which is not unexpected given the wide variability of tacrolimus Cmax and the small subpopulation sizes. These exploratory results suggest that this generic tacrolimus preparation would be expected to offer comparable bioavailability to the reference drug in these patient subpopulations. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Skin Erythema, Pigmentation and Hydration Kinetics after Ultraviolet Radiation-induced Photodamage in Southern Chinese Women.

PubMed

Wan, Miaojian; Hu, Rong; Xie, Xiaoyuan; Gong, Zijian; Yi, Jinling; Chen, Haiyan; Xie, Lin; Guan, Xiaomin; Guan, Lei; Lai, Wei

2017-10-01

Although there have been some studies about changes of skin erythema and pigmentation following ultraviolet radiation in other races, the relevant data in Chinese have never been achieved. Thus, we evaluated the long-time course of skin erythema, pigmentation and hydration changes after different doses of solar-simulated ultraviolet (SSUV) irradiation in 26 Chinese women for 168 days. The erythema index increased abruptly and peaked during 3 days of SSUV exposure, then slowly returned to the baseline level starting at day 7 and completely recovered during 168-day course of this study only in one minimal erythema doses (MED) SSUV irradiation. The melanin index started to slowly increase at day 3 of SSUV exposure, peaking at day 14 and gradually returned to the baseline level thereafter, but did not return to the baseline level during 168-day course in all doses. Skin hydration slowly declined at day 3 of exposure, hitting the lowest point at day 7, then slowly recovered starting at day 14 and completely returned to the baseline level at day 28 only in 1.5MED. These results will serve as baseline data on Chinese skin and provide useful references for the treatment of serious skin photodamage in Chinese. © 2017 The American Society of Photobiology.

SU-E-P-08: Establishment of Local Diagnostic Reference Levels of Routine Abdomen Exam in Computed Tomography According to Body Weight

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

Wang, H; Wang, Y; Weng, H

Purpose: The national diagnostic reference levels (NDRLs) is an efficient, concise and powerful standard for optimizing radiation protection of a patient. However, for each hospital the dose-reducing potential of focusing on establishment of local DRLs (LDRLs). A lot of study reported that Computed tomography exam contributed majority radiation dose in different medical modalities, therefore, routine abdomen CT exam was choose in initial pilot study in our study. Besides the mAs of routine abdomen CT exam was decided automatic exposure control by linear attenuation is relate to body shape of patient. In this study we would like to establish the localmore » diagnostic reference levels of routine abdomen exam in computed tomography according to body weight of patient. Methods and Materials: There are two clinical CT scanners (a Toshiba Aquilion and a Siemens Sensation) were performed in this study. For CT examinations the basic recommended dosimetric quantity is the Computed Tomography Dose Index (CTDI). The patient sample involved 82 adult patients of both sexes and divided into three groups by their body weight (50–60 kg, 60–70 kg, 70–80 kg).Carried out the routine abdomen examinations, and all exposure parameters have been collected and the corresponding CTDIv and DLP values have been determined. The average values were compared with the European DRLs. Results: The majority of patients (75%) were between 50–70 Kg of body weight, the numbers of patient in each group of weight were 40–50:7; 50–60:29; 60–70:33; 70–80:13. The LDRLs in each group were 10.81mGy, 14.46mGy, 20.27mGy and 21.04mGy, respectively. The DLP were 477mGy, 630mGy, 887mGy and 959mGy, respectively. No matter which group the LDRLs were lower than European DRLs. Conclusions: We would like to state that this was a pioneer work in local hospital in Chiayi. We hope that this may lead the way to further developments in Taiwan.« less

Sci-Sat AM: Radiation Dosimetry and Practical Therapy Solutions - 03: Energy dependence of a clinical probe-format calorimeter and its pertinence to absolute photon and electron beam dosimetry

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

Renaud, James; Seuntjens, Jan; Sarfehnia, Arman

Purpose: To evaluate the intrinsic and absorbed-dose energy dependence of a small-scale graphite calorimeter probe (GPC) developed for use as a routine clinical dosimeter. The influence of charge deposition on the response of the GPC was also assessed by performing absolute dosimetry in clinical linac-based electron beams. Methods: Intrinsic energy dependence was determined by performing constant-temperature calorimetry dose measurements in a water-equivalent solid phantom, under otherwise reference conditions, in five high-energy photon (63.5 < %dd(10){sub X} < 76.3), and five electron (2.3 cm < R{sub 50} < 8.3 cm) beams. Reference dosimetry was performed for all beams in question usingmore » an Exradin A19 ion chamber with a calibration traceable to national standards. The absorbed-dose component of the overall energy dependence was calculated using the EGSnrc egs-chamber user code. Results: A total of 72 measurements were performed with the GPC, resulting in a standard error on the mean absorbed dose of better than 0.3 % for all ten beams. For both the photon and electron beams, no statistically-significant energy dependence was observed experimentally. Peak-to-peak, variations in the relative response of the GPC across all beam qualities of a given radiation type were on the order of 1 %. No effects, either transient or permanent, were attributable to the charge deposited by the electron beams. Conclusions: The GPC’s apparent energy-independence, combined with its well-established linearity and dose rate independence, make it a potentially useful dosimetry system capable measuring photon and electron doses in absolute terms at the clinical level.« less

Organ doses for reference adult male and female undergoing computed tomography estimated by Monte Carlo simulations

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

Lee, Choonsik; Kim, Kwang Pyo; Long, Daniel

2011-03-15

Purpose: To develop a computed tomography (CT) organ dose estimation method designed to readily provide organ doses in a reference adult male and female for different scan ranges to investigate the degree to which existing commercial programs can reasonably match organ doses defined in these more anatomically realistic adult hybrid phantomsMethods: The x-ray fan beam in the SOMATOM Sensation 16 multidetector CT scanner was simulated within the Monte Carlo radiation transport code MCNPX2.6. The simulated CT scanner model was validated through comparison with experimentally measured lateral free-in-air dose profiles and computed tomography dose index (CTDI) values. The reference adult malemore » and female hybrid phantoms were coupled with the established CT scanner model following arm removal to simulate clinical head and other body region scans. A set of organ dose matrices were calculated for a series of consecutive axial scans ranging from the top of the head to the bottom of the phantoms with a beam thickness of 10 mm and the tube potentials of 80, 100, and 120 kVp. The organ doses for head, chest, and abdomen/pelvis examinations were calculated based on the organ dose matrices and compared to those obtained from two commercial programs, CT-EXPO and CTDOSIMETRY. Organ dose calculations were repeated for an adult stylized phantom by using the same simulation method used for the adult hybrid phantom. Results: Comparisons of both lateral free-in-air dose profiles and CTDI values through experimental measurement with the Monte Carlo simulations showed good agreement to within 9%. Organ doses for head, chest, and abdomen/pelvis scans reported in the commercial programs exceeded those from the Monte Carlo calculations in both the hybrid and stylized phantoms in this study, sometimes by orders of magnitude. Conclusions: The organ dose estimation method and dose matrices established in this study readily provides organ doses for a reference adult male and female for different CT scan ranges and technical parameters. Organ doses from existing commercial programs do not reasonably match organ doses calculated for the hybrid phantoms due to differences in phantom anatomy, as well as differences in organ dose scaling parameters. The organ dose matrices developed in this study will be extended to cover different technical parameters, CT scanner models, and various age groups.« less

Model-based iterative reconstruction and adaptive statistical iterative reconstruction: dose-reduced CT for detecting pancreatic calcification

PubMed Central

Katsura, Masaki; Akahane, Masaaki; Sato, Jiro; Matsuda, Izuru; Ohtomo, Kuni

2016-01-01

Background Iterative reconstruction methods have attracted attention for reducing radiation doses in computed tomography (CT). Purpose To investigate the detectability of pancreatic calcification using dose-reduced CT reconstructed with model-based iterative construction (MBIR) and adaptive statistical iterative reconstruction (ASIR). Material and Methods This prospective study approved by Institutional Review Board included 85 patients (57 men, 28 women; mean age, 69.9 years; mean body weight, 61.2 kg). Unenhanced CT was performed three times with different radiation doses (reference-dose CT [RDCT], low-dose CT [LDCT], ultralow-dose CT [ULDCT]). From RDCT, LDCT, and ULDCT, images were reconstructed with filtered-back projection (R-FBP, used for establishing reference standard), ASIR (L-ASIR), and MBIR and ASIR (UL-MBIR and UL-ASIR), respectively. A lesion (pancreatic calcification) detection test was performed by two blinded radiologists with a five-point certainty level scale. Results Dose-length products of RDCT, LDCT, and ULDCT were 410, 97, and 36 mGy-cm, respectively. Nine patients had pancreatic calcification. The sensitivity for detecting pancreatic calcification with UL-MBIR was high (0.67–0.89) compared to L-ASIR or UL-ASIR (0.11–0.44), and a significant difference was seen between UL-MBIR and UL-ASIR for one reader (P = 0.014). The area under the receiver-operating characteristic curve for UL-MBIR (0.818–0.860) was comparable to that for L-ASIR (0.696–0.844). The specificity was lower with UL-MBIR (0.79–0.92) than with L-ASIR or UL-ASIR (0.96–0.99), and a significant difference was seen for one reader (P < 0.01). Conclusion In UL-MBIR, pancreatic calcification can be detected with high sensitivity, however, we should pay attention to the slightly lower specificity. PMID:27110389

Metabolic disruption in male mice due to fetal exposure to low but not high doses of bisphenol A (BPA): Evidence for effects on body weight, food intake, adipocytes, leptin, adiponectin, insulin and glucose regulation

PubMed Central

Angle, Brittany M.; Do, Rylee Phuong; Ponzi, Davide; Stahlhut, Richard W.; Drury, Bertram E.; Nagel, Susan C.; Welshons, Wade V.; Besch-Williford, Cynthia L; Palanza, Paola; Parmigiani, Stefano; vom Saal, Frederick S.; Taylor, Julia A.

2013-01-01

Exposure to bisphenol A (BPA) is implicated in many aspects of metabolic disease in humans and experimental animals. We fed pregnant CD-1 mice BPA at doses ranging from 5 to 50,000 μg/kg/day, spanning 10-fold below the reference dose to 10-fold above the currently predicted no adverse effect level (NOAEL). At BPA doses below the NOAEL that resulted in average unconjugated BPA between 2 and 200pg/ml in fetal serum (AUC0–24h),we observed significant effects in adult male offspring: an age-related change in food intake, an increase in body weight and liver weight, abdominal adipocyte mass, number and volume, and in serum leptin and insulin, but a decrease in serum adiponectin and in glucose tolerance. For most of these outcomes non-monotonic dose–response relationships were observed; the highest BPA dose did not produce a significant effect for any outcome. A 0.1-μg/kg/day dose of DES resulted in some but not all low-dose BPA outcomes. PMID:23892310

Dose conversion factors for radon: recent developments.

PubMed

Marsh, James W; Harrison, John D; Laurier, Dominique; Blanchardon, Eric; Paquet, François; Tirmarche, Margot

2010-10-01

Epidemiological studies of the occupational exposure of miners and domestic exposures of the public have provided strong and complementary evidence of the risks of lung cancer following inhalation of radon progeny. Recent miner epidemiological studies, which include low levels of exposure, long duration of follow-up, and good quality of individual exposure data, suggest higher risks of lung cancer per unit exposure than assumed previously by the International Commission on Radiological Protection (ICRP). Although risks can be managed by controlling exposures, dose estimates are required for the control of occupational exposures and are also useful for comparing sources of public exposure. Currently, ICRP calculates doses from radon and its progeny using dose conversion factors from exposure (WLM) to dose (mSv) based on miner epidemiological studies, referred to as the epidemiological approach. Revision of these dose conversion factors using risk estimates based on the most recent epidemiological data gives values that are in good agreement with the results of calculations using ICRP biokinetic and dosimetric models, the dosimetric approach. ICRP now proposes to treat radon progeny in the same way as other radionuclides and to publish dose coefficients calculated using models, for use within the ICRP system of protection.

Diagnostic reference levels and complexity indices in interventional radiology: a national programme.

PubMed

Ruiz-Cruces, R; Vano, E; Carrera-Magariño, F; Moreno-Rodriguez, F; Soler-Cantos, M M; Canis-Lopez, M; Hernández-Armas, J; Diaz-Romero, F J; Rosales-Espizua, F; Fernandez-Soto, J M; Sanchez-Casanueva, R; Martin-Palanca, A; Perez-Martinez, M; Gil-Agudo, A; Zarca-Diaz, M A; Parra-Osorio, V; Muñoz Ruiz-Canela, J J; Moreno-Sanchez, T; Lopez-Medina, A; Moreno-Saiz, C; Galan-Montenegro, P; Gallego-Beuter, J J; Gonzalez-de-Garay, M; Zapata-Jimenez, J C; Pastor-Vega, J M; Cañete, S

2016-12-01

To propose national diagnostic reference levels (DRLs) for interventional radiology and to evaluate the impact of the procedural complexity on patient doses. Eight interventional radiology units from Spanish hospitals were involved in this project. The participants agreed to undergo common quality control procedures for X-ray systems. Kerma area product (KAP) was collected from a sample of 1,649 procedures. A consensus document established the criteria to evaluate the complexity of seven types of procedures. DRLs were set as the 3rd quartile of KAP values. The KAP (3rd quartile) in Gy cm 2 for the procedures included in the survey were: lower extremity arteriography (n = 784) 78; renal arteriography (n = 37) 107; transjugular hepatic biopsies (THB) (n = 30) 45; biliary drainage (BD) (n = 314) 30; uterine fibroid embolization (UFE) (n = 56) 214; colon endoprostheses (CE) (n = 31) 169; hepatic chemoembolization (HC) (n = 269) 303; femoropopliteal revascularization (FR) (n = 62) 119; and iliac stent (n = 66) 170. The complexity involved the increases in the following KAP factors from simple to complex procedures: THB x4; BD x13; UFE x3; CE x3; HC x5; FR x5 and IS x4. The evaluation of the procedure complexity in patient doses will allow the proper use of DRLs for the optimization of interventional radiology. • National DRLs for interventional procedures have been proposed given level of complexity • For clinical audits, the level of complexity should be taken into account. • An evaluation of the complexity levels of the procedure should be made.

Threshold-driven optimization for reference-based auto-planning

NASA Astrophysics Data System (ADS)

Long, Troy; Chen, Mingli; Jiang, Steve; Lu, Weiguo

2018-02-01

We study threshold-driven optimization methodology for automatically generating a treatment plan that is motivated by a reference DVH for IMRT treatment planning. We present a framework for threshold-driven optimization for reference-based auto-planning (TORA). Commonly used voxel-based quadratic penalties have two components for penalizing under- and over-dosing of voxels: a reference dose threshold and associated penalty weight. Conventional manual- and auto-planning using such a function involves iteratively updating the preference weights while keeping the thresholds constant, an unintuitive and often inconsistent method for planning toward some reference DVH. However, driving a dose distribution by threshold values instead of preference weights can achieve similar plans with less computational effort. The proposed methodology spatially assigns reference DVH information to threshold values, and iteratively improves the quality of that assignment. The methodology effectively handles both sub-optimal and infeasible DVHs. TORA was applied to a prostate case and a liver case as a proof-of-concept. Reference DVHs were generated using a conventional voxel-based objective, then altered to be either infeasible or easy-to-achieve. TORA was able to closely recreate reference DVHs in 5-15 iterations of solving a simple convex sub-problem. TORA has the potential to be effective for auto-planning based on reference DVHs. As dose prediction and knowledge-based planning becomes more prevalent in the clinical setting, incorporating such data into the treatment planning model in a clear, efficient way will be crucial for automated planning. A threshold-focused objective tuning should be explored over conventional methods of updating preference weights for DVH-guided treatment planning.

Multiparameter optimization of mammography: an update

NASA Astrophysics Data System (ADS)

Jafroudi, Hamid; Muntz, E. P.; Jennings, Robert J.

1994-05-01

Previously in this forum we have reported the application of multiparameter optimization techniques to the design of a minimum dose mammography system. The approach used a reference system to define the physical imaging performance required and the dose to which the dose for the optimized system should be compared. During the course of implementing the resulting design in hardware suitable for laboratory testing, the state of the art in mammographic imaging changed, so that the original reference system, which did not have a grid, was no longer appropriate. A reference system with a grid was selected in response to this change, and at the same time the optimization procedure was modified, to make it more general and to facilitate study of the optimized design under a variety of conditions. We report the changes in the procedure, and the results obtained using the revised procedure and the up- to-date reference system. Our results, which are supported by laboratory measurements, indicate that the optimized design can image small objects as well as the reference system using only about 30% of the dose required by the reference system. Hardware meeting the specification produced by the optimization procedure and suitable for clinical use is currently under evaluation in the Diagnostic Radiology Department at the Clinical Center, NH.

Effects of multiple ascending doses of the glucagon receptor antagonist PF-06291874 in patients with type 2 diabetes mellitus.

PubMed

Kazierad, D J; Bergman, A; Tan, B; Erion, D M; Somayaji, V; Lee, D S; Rolph, T

2016-08-01

To assess the pharmacokinetics, pharmacodynamics, safety and tolerability of multiple ascending doses of the glucagon receptor antagonist PF-06291874 in patients with type 2 diabetes mellitus (T2DM). Patients were randomized to oral PF-06291874 or placebo on a background of either metformin (Part A, Cohorts 1-5: 5-150 mg once daily), or metformin and sulphonylurea (Part B, Cohorts 1-2: 15 or 30 mg once daily) for 14-28 days. A mixed-meal tolerance test (MMTT) was administered on days -1 (baseline), 14 and 28. Assessments were conducted with regard to pharmacokinetics, various pharmacodynamic variables, safety and tolerability. Circulating amino acid concentrations were also measured. PF-06291874 exposure was approximately dose-proportional with a half-life of ∼19.7-22.7 h. Day 14 fasting plasma glucose and mean daily glucose values were reduced from baseline in a dose-dependent manner, with placebo-corrected decreases of 34.3 and 42.4 mg/dl, respectively, at the 150 mg dose. After the MMTT, dose-dependent increases in glucagon and total glucagon-like peptide-1 (GLP-1) were observed, although no meaningful changes were noted in insulin, C-peptide or active GLP-1 levels. Small dose-dependent increases in LDL cholesterol were observed, along with reversible increases in serum aminotransferases that were largely within the laboratory reference range. An increase in circulating gluconeogenic amino acids was also observed on days 2 and 14. All dose levels of PF-06291874 were well tolerated. PF-06291874 was well tolerated, has a pharmacokinetic profile suitable for once-daily dosing, and results in reductions in glucose with minimal risk of hypoglycaemia. © 2016 John Wiley & Sons Ltd.

Low dose evaluation of the antiandrogen flutamide following a Mode of Action approach.

PubMed

Sarrabay, A; Hilmi, C; Tinwell, H; Schorsch, F; Pallardy, M; Bars, R; Rouquié, D

2015-12-15

The dose-response characterization of endocrine mediated toxicity is an on-going debate which is controversial when exploring the nature of the dose-response curve and the effect at the low-end of the curve. To contribute to this debate we have assessed the effects of a wide range of dose levels of the antiandrogen flutamide (FLU) on 7-week male Wistar rats. FLU was administered by oral gavage at doses of 0, 0.001, 0.01, 0.1, 1 and 10mg/kg/day for 28 days. To evaluate the reproducibility, the study was performed 3 times. The molecular initiating event (MIE; AR antagonism), the key events (LH increase, Leydig cell proliferation and hyperplasia increases) and associated events involved in the mode of action (MOA) of FLU induced testicular toxicity were characterized to address the dose response concordance. Results showed no effects at low doses (<0.1mg/kg/day) for the different key events studied. The histopathological changes (Leydig cell hyperplasia) observed at 1 and 10mg/kg/day were associated with an increase in steroidogenesis gene expression in the testis from 1mg/kg/day, as well as an increase in testosterone blood level at 10mg/kg/day. Each key event dose-response was in good concordance with the MOA of FLU on the testis. From the available results, only monotonic dose-response curves were observed for the MIE, the key events, associated events and in effects observed in other sex related tissues. All the results, so far, show that the reference endocrine disruptor FLU induces threshold effects in a standard 28-day toxicity study on adult male rats. Copyright © 2015 Elsevier Inc. All rights reserved.

Assessment of dedicated low-dose cardiac micro-CT reconstruction algorithms using the left ventricular volume of small rodents as a performance measure

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

Maier, Joscha, E-mail: joscha.maier@dkfz.de; Sawall, Stefan; Kachelrieß, Marc

2014-05-15

Purpose: Phase-correlated microcomputed tomography (micro-CT) imaging plays an important role in the assessment of mouse models of cardiovascular diseases and the determination of functional parameters as the left ventricular volume. As the current gold standard, the phase-correlated Feldkamp reconstruction (PCF), shows poor performance in case of low dose scans, more sophisticated reconstruction algorithms have been proposed to enable low-dose imaging. In this study, the authors focus on the McKinnon-Bates (MKB) algorithm, the low dose phase-correlated (LDPC) reconstruction, and the high-dimensional total variation minimization reconstruction (HDTV) and investigate their potential to accurately determine the left ventricular volume at different dose levelsmore » from 50 to 500 mGy. The results were verified in phantom studies of a five-dimensional (5D) mathematical mouse phantom. Methods: Micro-CT data of eight mice, each administered with an x-ray dose of 500 mGy, were acquired, retrospectively gated for cardiac and respiratory motion and reconstructed using PCF, MKB, LDPC, and HDTV. Dose levels down to 50 mGy were simulated by using only a fraction of the projections. Contrast-to-noise ratio (CNR) was evaluated as a measure of image quality. Left ventricular volume was determined using different segmentation algorithms (Otsu, level sets, region growing). Forward projections of the 5D mouse phantom were performed to simulate a micro-CT scan. The simulated data were processed the same way as the real mouse data sets. Results: Compared to the conventional PCF reconstruction, the MKB, LDPC, and HDTV algorithm yield images of increased quality in terms of CNR. While the MKB reconstruction only provides small improvements, a significant increase of the CNR is observed in LDPC and HDTV reconstructions. The phantom studies demonstrate that left ventricular volumes can be determined accurately at 500 mGy. For lower dose levels which were simulated for real mouse data sets, the HDTV algorithm shows the best performance. At 50 mGy, the deviation from the reference obtained at 500 mGy were less than 4%. Also the LDPC algorithm provides reasonable results with deviation less than 10% at 50 mGy while PCF and MKB reconstruction show larger deviations even at higher dose levels. Conclusions: LDPC and HDTV increase CNR and allow for quantitative evaluations even at dose levels as low as 50 mGy. The left ventricular volumes exemplarily illustrate that cardiac parameters can be accurately estimated at lowest dose levels if sophisticated algorithms are used. This allows to reduce dose by a factor of 10 compared to today's gold standard and opens new options for longitudinal studies of the heart.« less

Technogenesis and the main levels of soil ecosystems' transformation in oil production areas

NASA Astrophysics Data System (ADS)

Buzmakov, Sergey

2017-04-01

The obtained experimental data, the results of field studies and the analysis of references make it possible to describe peculiarities of technogenic transformation of ecosystems. Experimental data allow to determine the main levels of oil pollution on the basis of changes in biotope properties and reaction of a biota. Background level. Pollution is absent. Biotope corresponds to natural zonal sequence. The content of oil products is up to 0,11 g/kg. First level: the dose of pollution is 0,8-1g of oil on 1 kg of soil. Conditions for plants' growth are optimum. Initially plants gain gross weight, and then lose it to the background level. The number of saprotrophes and oil oxidizing microorganisms rises. Second level: the pollution dose is up to 15 g per 1 kg of soil. The capillary moisture capacity increases reaching the maximum. The number of saprophytes and oil oxidizing microorganisms rises. Third level: the pollution dose is 15-21g per 1 kg of soil. Capillary capacity of soils decreases to background level. Time of filtration and absorption of moisture is increased. Fourth level: the pollution dose is 21-32g per 1 kg of soil. Anaerobic and hydrophobic conditions develop. The number of saprophytes and oil oxidizing microorganisms rises. Fifth level: the dose of pollution is 32 - 50g per 1 kg of soil. Formation of 3,4 benzpyrene increases sharply. The number of saprophytes and oil oxidizing microorganisms is at maximum level. Sixth level: the dose of pollution is 50 - 91g per 1 kg of soil. Formation of 3,4 benzpyrene is dangerous for biota. Time of absorption and filtration of water through the soil reaches its maximum. The number of saprophytes and oil oxidizing microorganisms decreases, but remains higher than at background level. Seventh level: the pollution dose is 91-150g per 1 kg of soil. The number of saprophytes and oil oxidizing microorganisms decreases to background level. Eighth level: the pollution dose is of 150-300 g per 1 kg of soil. The substratum becomes toxic. The number of saprophytes and oil oxidizing microorganisms is lower than at background level. Ninth level: the dose of pollution is 300 g per 1 kg of soil and above. Substratum is abiogenic. Field researches show that the influence of oil fields is manifested in the form of intake of emergency oil and emergency salty waters as well as ground water runoff and surface water containing salts and oil products from platforms of oil sites into surrounding land ecosystems, along with their atmospheric pollution. Degradation and recovery process is manifested in formation of a natural- technogenic ecosystem with azonal biotopes. Around powerful sources of pollution there should be created the manageable natural and technogenic ecosystems facilitating self-restoration of the environment. It is necessary to create a system of accumulating and transit ecosystems which would make it possible to carry out the degradation and dispersion of accumulated pollutants. Implementation of our proposals will result in stabilization of ecological situation.

SITE SPECIFIC REFERENCE PERSON PARAMETERS AND DERIVED CONCENTRATION STANDARDS FOR THE SAVANNAH RIVER SITE

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

Jannik, T.

2013-03-14

The purpose of this report is twofold. The first is to develop a set of behavioral parameters for a reference person specific for the Savannah River Site (SRS) such that the parameters can be used to determine dose to members of the public in compliance with Department of Energy (DOE) Order 458.1 “Radiation Protection of the Public and the Environment.” A reference person is a hypothetical, gender and age aggregation of human physical and physiological characteristics arrived at by international consensus for the purpose of standardizing radiation dose calculations. DOE O 458.1 states that compliance with the annual dose limitmore » of 100 mrem (1 mSv) to a member of the public may be demonstrated by calculating the dose to the maximally exposed individual (MEI) or to a representative person. Historically, for dose compliance, SRS has used the MEI concept, which uses adult dose coefficients and adult male usage parameters. Beginning with the 2012 annual site environmental report, SRS will be using the representative person concept for dose compliance. The dose to a representative person will be based on 1) the SRS-specific reference person usage parameters at the 95th percentile of appropriate national or regional data, which are documented in this report, 2) the reference person (gender and age averaged) ingestion and inhalation dose coefficients provided in DOE Derived Concentration Technical Standard (DOE-STD-1196-2011), and 3) the external dose coefficients provided in the DC_PAK3 toolbox. The second purpose of this report is to develop SRS-specific derived concentration standards (DCSs) for all applicable food ingestion pathways, ground shine, and water submersion. The DCS is the concentration of a particular radionuclide in water, in air, or on the ground that results in a member of the public receiving 100 mrem (1 mSv) effective dose following continuous exposure for one year. In DOE-STD-1196-2011, DCSs were developed for the ingestion of water, inhalation of air and submersion in air pathways, only. These DCSs are required by DOE O 458.1 to be used at all DOE sites in the design and conduct of radiological environmental protection programs. In this report, DCSs for the following additional pathways were considered and documented: ingestion of meat, dairy, grains, produce (fruits and vegetables), seafood, submersion in water and ground shine. These additional DCSs were developed using the same methods as in DOE-STD-1196-2011 and will be used at SRS, where appropriate, as screening and reference values.« less

Organ dose conversion coefficients for voxel models of the reference male and female from idealized photon exposures

NASA Astrophysics Data System (ADS)

Schlattl, H.; Zankl, M.; Petoussi-Henss, N.

2007-04-01

A new series of organ equivalent dose conversion coefficients for whole body external photon exposure is presented for a standardized couple of human voxel models, called Rex and Regina. Irradiations from broad parallel beams in antero-posterior, postero-anterior, left- and right-side lateral directions as well as from a 360° rotational source have been performed numerically by the Monte Carlo transport code EGSnrc. Dose conversion coefficients from an isotropically distributed source were computed, too. The voxel models Rex and Regina originating from real patient CT data comply in body and organ dimensions with the currently valid reference values given by the International Commission on Radiological Protection (ICRP) for the average Caucasian man and woman, respectively. While the equivalent dose conversion coefficients of many organs are in quite good agreement with the reference values of ICRP Publication 74, for some organs and certain geometries the discrepancies amount to 30% or more. Differences between the sexes are of the same order with mostly higher dose conversion coefficients in the smaller female model. However, much smaller deviations from the ICRP values are observed for the resulting effective dose conversion coefficients. With the still valid definition for the effective dose (ICRP Publication 60), the greatest change appears in lateral exposures with a decrease in the new models of at most 9%. However, when the modified definition of the effective dose as suggested by an ICRP draft is applied, the largest deviation from the current reference values is obtained in postero-anterior geometry with a reduction of the effective dose conversion coefficient by at most 12%.

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

Ma, R; Zhu, X; Li, S

Purpose: High Dose Rate (HDR) brachytherapy forward planning is principally an iterative process; hence, plan quality is affected by planners’ experiences and limited planning time. Thus, this may lead to sporadic errors and inconsistencies in planning. A statistical tool based on previous approved clinical treatment plans would help to maintain the consistency of planning quality and improve the efficiency of second checking. Methods: An independent dose calculation tool was developed from commercial software. Thirty-three previously approved cervical HDR plans with the same prescription dose (550cGy), applicator type, and treatment protocol were examined, and ICRU defined reference point doses (bladder, vaginalmore » mucosa, rectum, and points A/B) along with dwell times were collected. Dose calculation tool then calculated appropriate range with a 95% confidence interval for each parameter obtained, which would be used as the benchmark for evaluation of those parameters in future HDR treatment plans. Model quality was verified using five randomly selected approved plans from the same dataset. Results: Dose variations appears to be larger at the reference point of bladder and mucosa as compared with rectum. Most reference point doses from verification plans fell between the predicted range, except the doses of two points of rectum and two points of reference position A (owing to rectal anatomical variations & clinical adjustment in prescription points, respectively). Similar results were obtained for tandem and ring dwell times despite relatively larger uncertainties. Conclusion: This statistical tool provides an insight into clinically acceptable range of cervical HDR plans, which could be useful in plan checking and identifying potential planning errors, thus improving the consistency of plan quality.« less

Use of short-term toxicity data for prediction of long-term health effects

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

Hartley, W.R.; Ohanian, E.V.

1988-01-01

Under the Safe Drinking Water Act Amendments of 1986, the US Environmental Protection Agency determines Maximum Contaminant Level Goals (MCLGs) and enforceable Maximum Contaminant Levels (MCLs) or provides lifetime health advisories (HAs) in the absence of regulatory standards. The critical value for calculation of the lifetime level is the reference dose (RfD). The RfD is an estimate of a lifetime dose which is likely to be without significant risk to human populations. The RfD is determined by dividing the no-observed-adverse-effect level (NOAEL) or the lowest-observed-adverse-effect level (LOAEL) by an uncertainty factor (UF). The NOAEL or LOAEL is determined from toxicologicalmore » or epidemiological studies. For many chemicals, human toxicological or epidemiological data are not available. Chronic mammalian studies are sometimes unavailable. Faced with the need for providing guidance for the increasing number of chemicals threatening our drinking water sources, this paper considers the possibility of providing provisional RfDs using data from toxicological studies of less than ninety days duration. The current UF approach is reviewed along with some proposed mathematical models for extrapolation of NOAELs from dose-response data. The current UF approach to developing the RfD is protective and conservative. More research is needed on the relationship of short- and long-term toxicity data to improve our current approach.« less

Dose-rate effects of protons on in vivo activation of nuclear factor-kappa B and cytokines in mouse bone marrow cells

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

Rithidech, K.N.; Rusek, A.; Reungpatthanaphong, P.

2010-05-28

The objective of this study was to determine the kinetics of nuclear factor-kappa B (NF-{kappa}B) activation and cytokine expression in bone marrow (BM) cells of exposed mice as a function of the dose rate of protons. The cytokines included in this study are pro-inflammatory [i.e., tumor necrosis factor-alpha (TNF-{alpha}), interleukin-1beta (IL-1{beta}), and IL-6] and anti-inflammatory cytokines (i.e., IL-4 and IL-10). We gave male BALB/cJ mice a whole-body exposure to 0 (sham-controls) or 1.0 Gy of 100 MeV protons, delivered at 5 or 10 mGy min{sup -1}, the dose and dose rates found during solar particle events in space. As amore » reference radiation, groups of mice were exposed to 0 (sham-controls) or 1 Gy of {sup 137}Cs {gamma} rays (10 mGy min{sup -1}). After irradiation, BM cells were collected at 1.5, 3, 24 h, and 1 month for analyses (five mice per treatment group per harvest time). The results indicated that the in vivo time course of effects induced by a single dose of 1 Gy of 100 MeV protons or {sup 137}Cs {gamma} rays, delivered at 10 mGy min{sup -1}, was similar. Although statistically significant levels of NF-{kappa}B activation and pro-inflammatory cytokines in BM cells of exposed mice when compared to those in the corresponding sham controls (Student's t-test, p < 0.05 or < 0.01) were induced by either dose rate, these levels varied over time for each protein. Further, only a dose rate of 5 mGy min{sup -1} induced significant levels of anti-inflammatory cytokines. The results indicate dose-rate effects of protons.« less

Hemolytic Potential of Tafenoquine in Female Volunteers Heterozygous for Glucose-6-Phosphate Dehydrogenase (G6PD) Deficiency (G6PD Mahidol Variant) versus G6PD-Normal Volunteers.

PubMed

Rueangweerayut, Ronnatrai; Bancone, Germana; Harrell, Emma J; Beelen, Andrew P; Kongpatanakul, Supornchai; Möhrle, Jörg J; Rousell, Vicki; Mohamed, Khadeeja; Qureshi, Ammar; Narayan, Sushma; Yubon, Nushara; Miller, Ann; Nosten, François H; Luzzatto, Lucio; Duparc, Stephan; Kleim, Jörg-Peter; Green, Justin A

2017-09-01

Tafenoquine is an 8-aminoquinoline under investigation for the prevention of relapse in Plasmodium vivax malaria. This open-label, dose-escalation study assessed quantitatively the hemolytic risk with tafenoquine in female healthy volunteers heterozygous for the Mahidol 487A glucose-6-phosphate dehydrogenase (G6PD)-deficient variant versus G6PD-normal females, and with reference to primaquine. Six G6PD-heterozygous subjects (G6PD enzyme activity 40-60% of normal) and six G6PD-normal subjects per treatment group received single-dose tafenoquine (100, 200, or 300 mg) or primaquine (15 mg × 14 days). All participants had pretreatment hemoglobin levels ≥ 12.0 g/dL. Tafenoquine dose escalation stopped when hemoglobin decreased by ≥ 2.5 g/dL (or hematocrit decline ≥ 7.5%) versus pretreatment values in ≥ 3/6 subjects. A dose-response was evident in G6PD-heterozygous subjects ( N = 15) receiving tafenoquine for the maximum decrease in hemoglobin versus pretreatment values. Hemoglobin declines were similar for tafenoquine 300 mg (-2.65 to -2.95 g/dL [ N = 3]) and primaquine (-1.25 to -3.0 g/dL [ N = 5]). Two further cohorts of G6PD-heterozygous subjects with G6PD enzyme levels 61-80% ( N = 2) and > 80% ( N = 5) of the site median normal received tafenoquine 200 mg; hemolysis was less pronounced at higher G6PD enzyme activities. Tafenoquine hemolytic potential was dose dependent, and hemolysis was greater in G6PD-heterozygous females with lower G6PD enzyme activity levels. Single-dose tafenoquine 300 mg did not appear to increase the severity of hemolysis versus primaquine 15 mg × 14 days.

Evaluation and implementation of triple‐channel radiochromic film dosimetry in brachytherapy

PubMed Central

Bradley, David; Nisbet, Andrew

2014-01-01

The measurement of dose distributions in clinical brachytherapy, for the purpose of quality control, commissioning or dosimetric audit, is challenging and requires development. Radiochromic film dosimetry with a commercial flatbed scanner may be suitable, but careful methodologies are required to control various sources of uncertainty. Triple‐channel dosimetry has recently been utilized in external beam radiotherapy to improve the accuracy of film dosimetry, but its use in brachytherapy, with characteristic high maximum doses, steep dose gradients, and small scales, has been less well researched. We investigate the use of advanced film dosimetry techniques for brachytherapy dosimetry, evaluating uncertainties and assessing the mitigation afforded by triple‐channel dosimetry. We present results on postirradiation film darkening, lateral scanner effect, film surface perturbation, film active layer thickness, film curling, and examples of the measurement of clinical brachytherapy dose distributions. The lateral scanner effect in brachytherapy film dosimetry can be very significant, up to 23% dose increase at 14 Gy, at ± 9 cm lateral from the scanner axis for simple single‐channel dosimetry. Triple‐channel dosimetry mitigates the effect, but still limits the useable width of a typical scanner to less than 8 cm at high dose levels to give dose uncertainty to within 1%. Triple‐channel dosimetry separates dose and dose‐independent signal components, and effectively removes disturbances caused by film thickness variation and surface perturbations in the examples considered in this work. The use of reference dose films scanned simultaneously with brachytherapy test films is recommended to account for scanner variations from calibration conditions. Postirradiation darkening, which is a continual logarithmic function with time, must be taken into account between the reference and test films. Finally, films must be flat when scanned to avoid the Callier‐like effects and to provide reliable dosimetric results. We have demonstrated that radiochromic film dosimetry with GAFCHROMIC EBT3 film and a commercial flatbed scanner is a viable method for brachytherapy dose distribution measurement, and uncertainties may be reduced with triple‐channel dosimetry and specific film scan and evaluation methodologies. PACS numbers: 87.55.Qr, 87.56.bg, 87.55.km PMID:25207417

Organ dose calculations by Monte Carlo modeling of the updated VCH adult male phantom against idealized external proton exposure

NASA Astrophysics Data System (ADS)

Zhang, Guozhi; Liu, Qian; Zeng, Shaoqun; Luo, Qingming

2008-07-01

The voxel-based visible Chinese human (VCH) adult male phantom has offered a high-quality test bed for realistic Monte Carlo modeling in radiological dosimetry simulations. The phantom has been updated in recent effort by adding newly segmented organs, revising walled and smaller structures as well as recalibrating skeletal marrow distributions. The organ absorbed dose against external proton exposure was calculated at a voxel resolution of 2 × 2 × 2 mm3 using the MCNPX code for incident energies from 20 MeV to 10 GeV and for six idealized irradiation geometries: anterior-posterior (AP), posterior-anterior (PA), left-lateral (LLAT), right-lateral (RLAT), rotational (ROT) and isotropic (ISO), respectively. The effective dose on the VCH phantom was derived in compliance with the evaluation scheme for the reference male proposed in the 2007 recommendations of the International Commission on Radiological Protection (ICRP). Algorithm transitions from the revised radiation and tissue weighting factors are accountable for approximately 90% and 10% of effective dose discrepancies in proton dosimetry, respectively. Results are tabulated in terms of fluence-to-dose conversion coefficients for practical use and are compared with data from other models available in the literature. Anatomical variations between various computational phantoms lead to dose discrepancies ranging from a negligible level to 100% or more at proton energies below 200 MeV, corresponding to the spatial geometric locations of individual organs within the body. Doses show better agreement at higher energies and the deviations are mostly within 20%, to which the organ volume and mass differences should be of primary responsibility. The impact of body size on dose distributions was assessed by dosimetry of a scaled-up VCH phantom that was resized in accordance with the height and total mass of the ICRP reference man. The organ dose decreases with the directionally uniform enlargement of voxels. Potential pathways to improve the VCH phantom have also been briefly addressed. This work pertains to VCH-based systematic multi-particle dose investigations and will contribute to comparative dosimetry studies of ICRP standardized voxel phantoms in the near future.

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

Wen, N; Lu, S; Qin, Y

Purpose: To evaluate the dosimetric uncertainty associated with Gafchromic (EBT3) films and establish an absolute dosimetry protocol for Stereotactic Radiosurgery (SRS) and Stereotactic Body Radiotherapy (SBRT). Methods: EBT3 films were irradiated at each of seven different dose levels between 1 and 15 Gy with open fields, and standard deviations of dose maps were calculated at each color channel for evaluation. A scanner non-uniform response correction map was built by registering and comparing film doses to the reference diode array-based dose map delivered with the same doses. To determine the temporal dependence of EBT3 films, the average correction factors of differentmore » dose levels as a function of time were evaluated up to four days after irradiation. An integrated film dosimetry protocol was developed for dose calibration, calibration curve fitting, dose mapping, and profile/gamma analysis. Patient specific quality assurance (PSQA) was performed for 93 SRS/SBRT treatment plans. Results: The scanner response varied within 1% for the field sizes less than 5 × 5 cm{sup 2}, and up to 5% for the field sizes of 10 × 10 cm{sup 2}. The scanner correction method was able to remove visually evident, irregular detector responses found for larger field sizes. The dose response of the film changed rapidly (∼10%) in the first two hours and plateaued afterwards, ∼3% change between 2 and 24 hours. The mean uncertainties (mean of the standard deviations) were <0.5% over the dose range 1∼15Gy for all color channels for the OD response curves. The percentage of points passing the 3%/1mm gamma criteria based on absolute dose analysis, averaged over all tests, was 95.0 ± 4.2. Conclusion: We have developed an absolute film dose dosimetry protocol using EBT3 films. The overall uncertainty has been established to be approximately 1% for SRS and SBRT PSQA. The work was supported by a Research Scholar Grant, RSG-15-137-01-CCE from the American Cancer Society.« less

Proposed Oral Reference Dose (RfD) for Barium and Compounds (Final Report, 2004)

EPA Science Inventory

This document is the final report from the 2004 external peer review of the Proposed Oral Reference Dose (RfD) for Barium and Compounds, prepared by the U.S. Environmental Protection Agency (EPA), National Center for Environmental Assessment (NCEA), for the Integrated Risk...

Very low-dose (0.15 mGy) chest CT protocols using the COPDGene 2 test object and a third-generation dual-source CT scanner with corresponding third-generation iterative reconstruction software.

PubMed

Newell, John D; Fuld, Matthew K; Allmendinger, Thomas; Sieren, Jered P; Chan, Kung-Sik; Guo, Junfeng; Hoffman, Eric A

2015-01-01

The purpose of this study was to evaluate the impact of ultralow radiation dose single-energy computed tomographic (CT) acquisitions with Sn prefiltration and third-generation iterative reconstruction on density-based quantitative measures of growing interest in phenotyping pulmonary disease. The effects of both decreasing dose and different body habitus on the accuracy of the mean CT attenuation measurements and the level of image noise (SD) were evaluated using the COPDGene 2 test object, containing 8 different materials of interest ranging from air to acrylic and including various density foams. A third-generation dual-source multidetector CT scanner (Siemens SOMATOM FORCE; Siemens Healthcare AG, Erlangen, Germany) running advanced modeled iterative reconstruction (ADMIRE) software (Siemens Healthcare AG) was used.We used normal and very large body habitus rings at dose levels varying from 1.5 to 0.15 mGy using a spectral-shaped (0.6-mm Sn) tube output of 100 kV(p). Three CT scans were obtained at each dose level using both rings. Regions of interest for each material in the test object scans were automatically extracted. The Hounsfield unit values of each material using weighted filtered back projection (WFBP) at 1.5 mGy was used as the reference value to evaluate shifts in CT attenuation at lower dose levels using either WFBP or ADMIRE. Statistical analysis included basic statistics, Welch t tests, multivariable covariant model using the F test to assess the significance of the explanatory (independent) variables on the response (dependent) variable, and CT mean attenuation, in the multivariable covariant model including reconstruction method. Multivariable regression analysis of the mean CT attenuation values showed a significant difference with decreasing dose between ADMIRE and WFBP. The ADMIRE has reduced noise and more stable CT attenuation compared with WFBP. There was a strong effect on the mean CT attenuation values of the scanned materials for ring size (P < 0.0001) and dose level (P < 0.0001). The number of voxels in the region of interest for the particular material studied did not demonstrate a significant effect (P > 0.05). The SD was lower with ADMIRE compared with WFBP at all dose levels and ring sizes (P < 0.05). The third-generation dual-source CT scanners using third-generation iterative reconstruction methods can acquire accurate quantitative CT images with acceptable image noise at very low-dose levels (0.15 mGy). This opens up new diagnostic and research opportunities in CT phenotyping of the lung for developing new treatments and increased understanding of pulmonary disease.

A Survey of Pediatric CT Protocols and Radiation Doses in South Korean Hospitals to Optimize the Radiation Dose for Pediatric CT Scanning

PubMed Central

Hwang, Jae-Yeon; Do, Kyung-Hyun; Yang, Dong Hyun; Cho, Young Ah; Yoon, Hye-Kyung; Lee, Jin Seong; Koo, Hyun Jung

2015-01-01

Abstract Children are at greater risk of radiation exposure than adults because the rapidly dividing cells of children tend to be more radiosensitive and they have a longer expected life time in which to develop potential radiation injury. Some studies have surveyed computed tomography (CT) radiation doses and several studies have established diagnostic reference levels according to patient age or body size; however, no survey of CT radiation doses with a large number of patients has yet been carried out in South Korea. The aim of the present study was to investigate the radiation dose in pediatric CT examinations performed throughout South Korea. From 512 CT (222 brain CT, 105 chest CT, and 185 abdominopelvic CT) scans that were referred to our tertiary hospital, a dose report sheet was available for retrospective analysis of CT scan protocols and dose, including the volumetric CT dose index (CTDIvol), dose-length product (DLP), effective dose, and size-specific dose estimates (SSDE). At 55.2%, multiphase CT was the most frequently performed protocol for abdominopelvic CT. Tube current modulation was applied most often in abdominopelvic CT and chest CT, accounting for 70.1% and 62.7%, respectively. Regarding the CT dose, the interquartile ranges of the CTDIvol were 11.1 to 22.5 (newborns), 16.6 to 39.1 (≤1 year), 14.6 to 41.7 (2–5 years), 23.5 to 44.1 (6–10 years), and 31.4 to 55.3 (≤15 years) for brain CT; 1.3 to 5.7 (≤1 year), 3.9 to 6.8 (2–5 years), 3.9 to 9.3 (6–10 years), and 7.7 to 13.8 (≤15 years) for chest CT; and 4.0 to 7.5 (≤1 year), 4.2 to 8.9 (2–5 years), 5.7 to 12.4 (6–10 years), and 7.6 to 16.6 (≤15 years) for abdominopelvic CT. The SSDE and CTDIvol were well correlated for patients <5 years old, whereas the CTDIvol was lower in patients ≥6 years old. Our study describes the various parameters and dosimetry metrics of pediatric CT in South Korea. The CTDIvol, DLP, and effective dose were generally lower than in German and UK surveys, except in certain age groups. PMID:26683922

Research on Ratio of Dosage of Drugs in Traditional Chinese Prescriptions by Data Mining.

PubMed

Yu, Xing-Wen; Gong, Qing-Yue; Hu, Kong-Fa; Mao, Wen-Jing; Zhang, Wei-Ming

2017-01-01

Maximizing the effectiveness of prescriptions and minimizing adverse effects of drugs is a key component of the health care of patients. In the practice of traditional Chinese medicine (TCM), it is important to provide clinicians a reference for dosing of prescribed drugs. The traditional Cheng-Church biclustering algorithm (CC) is optimized and the data of TCM prescription dose is analyzed by using the optimization algorithm. Based on an analysis of 212 prescriptions related to TCM treatment of kidney diseases, the study generated 87 prescription dose quantum matrices and each sub-matrix represents the referential value of the doses of drugs in different recipes. The optimized CC algorithm can effectively eliminate the interference of zero in the original dose matrix of TCM prescriptions and avoid zero appearing in output sub-matrix. This results in the ability to effectively analyze the reference value of drugs in different prescriptions related to kidney diseases, so as to provide valuable reference for clinicians to use drugs rationally.

Derivation of mean dose tolerances for new fractionation schemes and treatment modalities

NASA Astrophysics Data System (ADS)

Perkó, Zoltán; Bortfeld, Thomas; Hong, Theodore; Wolfgang, John; Unkelbach, Jan

2018-02-01

Avoiding toxicities in radiotherapy requires the knowledge of tolerable organ doses. For new, experimental fractionation schemes (e.g. hypofractionation) these are typically derived from traditional schedules using the biologically effective dose (BED) model. In this report we investigate the difficulties of establishing mean dose tolerances that arise since the mean BED depends on the entire spatial dose distribution, rather than on the dose level alone. A formula has been derived to establish mean physical dose constraints such that they are mean BED equivalent to a reference treatment scheme. This formula constitutes a modified BED equation where the influence of the spatial dose distribution is summarized in a single parameter, the dose shape factor. To quantify effects we analyzed 24 liver cancer patients for whom both proton and photon IMRT treatment plans were available. The results show that the standard BED equation—neglecting the spatial dose distribution—can overestimate mean dose tolerances for hypofractionated treatments by up to 20%. The shape difference between photon and proton dose distributions can cause 30-40% differences in mean physical dose for plans having identical mean BEDs. Converting hypofractionated, 5/15-fraction proton doses to mean BED equivalent photon doses in traditional 35-fraction regimens resulted in up to 10 Gy higher doses than applying the standard BED formula. The dose shape effect should be accounted for to avoid overestimation of mean dose tolerances, particularly when estimating constraints for hypofractionated regimens. Additionally, tolerances established for one treatment modality cannot necessarily be applied to other modalities with drastically different dose distributions, such as proton therapy. Last, protons may only allow marginal (5-10%) dose escalation if a fraction-size adjusted organ mean dose is constraining instead of a physical dose.

Estimating human-equivalent no observed adverse-effect levels for VOCs (volatile organic compounds) based on minimal knowledge of physiological parameters. Technical paper

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

Overton, J.H.; Jarabek, A.M.

1989-01-01

The U.S. EPA advocates the assessment of health-effects data and calculation of inhaled reference doses as benchmark values for gauging systemic toxicity to inhaled gases. The assessment often requires an inter- or intra-species dose extrapolation from no observed adverse effect level (NOAEL) exposure concentrations in animals to human equivalent NOAEL exposure concentrations. To achieve this, a dosimetric extrapolation procedure was developed based on the form or type of equations that describe the uptake and disposition of inhaled volatile organic compounds (VOCs) in physiologically-based pharmacokinetic (PB-PK) models. The procedure assumes allometric scaling of most physiological parameters and that the value ofmore » the time-integrated human arterial-blood concentration must be limited to no more than to that of experimental animals. The scaling assumption replaces the need for most parameter values and allows the derivation of a simple formula for dose extrapolation of VOCs that gives equivalent or more-conservative exposure concentrations values than those that would be obtained using a PB-PK model in which scaling was assumed.« less

A single institution study of radiation dose received from CT imaging: A comparison to Malaysian NDRL

NASA Astrophysics Data System (ADS)

Osman, N. D.; Shamsuri, S. B. M.; Tan, Y. W.; Razali, M. A. S. M.; Isa, S. M.

2017-05-01

Advancement of CT technology has led to an increase in CT scanning as it improves the diagnosis. However, it is important to assess health risk of patients associated with ionising radiation received from CT. This study evaluated current dose distributions at Advanced Medical and Dental Institute (AMDI), Malaysia and was used to establish Local Diagnostic Reference Level (LDRL). Dose indicators such as CT Dose Index (CTDIvol and CTDIw) and Dose-Length Product (DLP) were gathered for all routine CT examinations performed at the Imaging Unit, AMDI from January 2015 to June 2016. The first and third quartile values for each dose indicator were determined. A total of 364 CT studies were performed during that period with the highest number of cases being Thorax-Abdomen-Pelvis (TAP) study (57% of total study). The CTDIw ranged between 2.0 mGy to 23.4 mGy per procedure. DLP values were ranged between 94 mGy.cm to 1687 mGy.cm. The local dose data was compared with the national DRL to monitor the current CT practice at AMDI and LDRL will be established from the calculated third quartile values of dose distribution. From the results, some of the local dose values exceeded the Malaysian and further evaluation is important to ensure the dose optimisation for patients.

Investigation of Natural Radioactivity in a Monazite Processing Plant in Japan.

PubMed

Iwaoka, Kazuki; Yajima, Kazuaki; Suzuki, Toshikazu; Yonehara, Hidenori; Hosoda, Masahiro; Tokonami, Shinji; Kanda, Reiko

2017-09-01

Monazite is a naturally occurring radioactive material that is processed for use in a variety of domestic applications. At present, there is little information available on potential radiation doses experienced by people working with monazite. The ambient dose rate and activity concentration of natural radionuclides in raw materials, products, and dust in work sites as well as the Rn and Rn concentrations in work sites were measured in a monazite processing plant in Japan. Dose estimations for plant workers were also conducted. The activity concentration of the U series in raw materials and products for the monazite processing plant was found to be higher than the relevant values described in the International Atomic Energy Agency Safety Standards. The ambient dose rates in the raw material yard were higher than those in other work sites. Moreover, the activity concentrations of dust in the milling site were higher than those in other work sites. The Rn concentrations in all work sites were almost the same as those in regular indoor environments in Japan. The Rn concentrations in all work sites were much higher than those in regular indoor environments in Japan. The maximum value of the effective dose for workers was 0.62 mSv y, which is lower than the reference level range (1-20 mSv y) for abnormally high levels of natural background radiation published in the International Commission of Radiological Protection Publication 103.

The mandate and work of ICRP Committee 3 on radiological protection in medicine.

PubMed

Miller, D L; Martin, C J; Rehani, M M

2018-01-01

The mandate of Committee 3 of the International Commission on Radiological Protection (ICRP) is concerned with the protection of persons and unborn children when ionising radiation is used in medical diagnosis, therapy, and biomedical research. Protection in veterinary medicine has been newly added to the mandate. Committee 3 develops recommendations and guidance in these areas. The most recent documents published by ICRP that relate to radiological protection in medicine are 'Radiological protection in cone beam computed tomography' (ICRP Publication 129) and 'Radiological protection in ion beam radiotherapy' (ICRP Publication 127). A report in cooperation with ICRP Committee 2 entitled 'Radiation dose to patients from radiopharmaceuticals: a compendium of current information related to frequently used substances' (ICRP Publication 128) has also been published. 'Diagnostic reference levels in medical imaging' (ICRP Publication 135), published in 2017, provides specific advice on the setting and use of diagnostic reference levels for diagnostic and interventional radiology, digital imaging, computed tomography, nuclear medicine, paediatrics, and multi-modality procedures. 'Occupational radiological protection in interventional procedures' was published in March 2018 as ICRP Publication 139. A document on radiological protection in therapy with radiopharmaceuticals is likely to be published in 2018. Work is in progress on several other topics, including appropriate use of effective dose in collaboration with the other ICRP committees, guidance for occupational radiological protection in brachytherapy, justification in medical imaging, and radiation doses to patients from radiopharmaceuticals (an update to ICRP Publication 128). Committee 3 is also considering the development of guidance on radiological protection in medicine related to individual radiosusceptibility, in collaboration with ICRP Committee 1.

Proposed Multicenter Studies

DTIC Science & Technology

2009-02-01

One plasma- derived AT product is Thrombate, produced by Bayer. Recombinant AT (rhAT) is made on a large scale in the milk of transgenic goats and is...infusions of rhAT to increase AT levels to 200 and 500% of normal, followed by infusions of endotoxin . AT dose dependently decreased tissue factor...injury. REFERENCES 1. Edmunds T, Van Patten SM, Pollock J, et al. Transgenically produced human antithrombin: structural and functional comparison to

Patient doses from CT examinations in Turkey.

PubMed

Ataç, Gökçe Kaan; Parmaksız, Aydın; İnal, Tolga; Bulur, Emine; Bulgurlu, Figen; Öncü, Tolga; Gündoğdu, Sadi

2015-01-01

We aimed to establish the first diagnostic reference levels (DRLs) for computed tomography (CT) examinations in adult and pediatric patients in Turkey and compare these with international DRLs. CT performance information and examination parameters (for head, chest, high-resolution CT of the chest [HRCT-chest], abdominal, and pelvic protocols) from 1607 hospitals were collected via a survey. Dose length products and effective doses for standard patient sizes were calculated from the reported volume CT dose index (CTDIvol). The median number of protocols reported from the 167 responding hospitals (10% response rate) was 102 across five different age groups. Third quartile CTDIvol values for adult pelvic and all pediatric body protocols were higher than the European Commission standards but were comparable to studies conducted in other countries. The radiation dose indicators for adult patients were similar to those reported in the literature, except for those associated with head protocols. CT protocol optimization is necessary for adult head and pediatric chest, HRCT-chest, abdominal, and pelvic protocols. The findings from this study are recommended for use as national DRLs in Turkey.

Transcript and protein environmental biomarkers in fish--a review.

PubMed

Tom, Moshe; Auslander, Meirav

2005-04-01

The levels of contaminant-affected gene products (transcripts and proteins) are increasingly utilized as environmental biomarkers, and their appropriate implementation as diagnostic tools is discussed. The required characteristics of a gene product biomarker are accurate evaluation using properly normalized absolute units, aiming at long-term comparability of biomarker levels over a wide geographical range and among many laboratories. Quantitative RT-PCR and competitive ELISA are suggested as preferred evaluation methods for transcript and protein, respectively. Constitutively expressed RNAs or proteins which are part of the examined homogenate are suggested as normalizing agents, compensating for variable processing efficiency. Essential characterization of expression patterns is suggested, providing reference values to be compared to the monitored levels. This comparison would enable estimation of the intensity of biological effects of contaminants. Contaminant-independent reference expression patterns should include natural fluctuations of the biomarker level. Contaminant-dependent patterns should include dose response to model contaminants chronically administered in two environmentally-realistic routes, reaching extreme sub-lethal affected levels. Recent studies using fish as environmental sentinel species, applying gene products as environmental biomarkers, and implementing at least part of the depicted methodologies are reviewed.

Low-dose Norfloxacin-treated leptospires induce less IL-1β release in J774A.1 cells following discrepant leptospiral gene expression.

PubMed

Cao, Yongguo; Xie, Xufeng; Zhang, Wenlong; Wu, Dianjun; Tu, Changchun

2018-06-01

Currently, accumulating evidence is challenging subtherapeutic therapy. Low-dose Norfloxacin (Nor) has been reported to suppress the immune response and worsen leptospirosis. In this study, we investigated the influence of low-dose Nor (0.03 μg/ml, 0.06 μg/ml, 0.125 μg/ml) on leptospiral gene expression and analyzed the immunomodulatory effects of low-dose Nor-treated leptospires in J774A.1 cells. To study the expression profiles of low-dose Nor-treated leptospires, we chose LipL71/LipL21 as reference genes determined by the geNorm applet in this experiment. The results showed that low-dose Nor up-regulated the expression of FlaB and inhibited the expression of 16S rRNA, LipL32, LipL41, Loa22, KdpA, and KdpB compared with the untreated leptospires. These results indicated that low-dose Nor could regulate leptospiral gene expression. Using RT-PCR, the gene expression of IL-1β and TNF-α in J774A.1 cells was detected. Nor-treated leptospires induced higher expression levels of both IL-1β and TNF-α. However, when analyzed by ELISA, the release of mature IL-1β was reduced compared with that observed in cells induced with no Nor-treated leptospires, although the TNF-α protein level showed no significant change. Our study indicated that the gene expression of leptospires could be modulated by low-dose Nor, which induced less IL-1β release in J774A.1 cells. Copyright © 2018 Elsevier Ltd. All rights reserved.

Estimation of absorbed dose in clinical radiotherapy linear accelerator beams: Effect of ion chamber calibration and long-term stability

PubMed Central

Ravichandran, Ramamoorthy; Binukumar, Johnson Pichy; Davis, Cheriyathmanjiyil Antony

2013-01-01

The measured dose in water at reference point in phantom is a primary parameter for planning the treatment monitor units (MU); both in conventional and intensity modulated/image guided treatments. Traceability of dose accuracy therefore still depends mainly on the calibration factor of the ion chamber/dosimeter provided by the accredited Secondary Standard Dosimetry Laboratories (SSDLs), under International Atomic Energy Agency (IAEA) network of laboratories. The data related to Nd,water calibrations, thermoluminescent dosimetry (TLD) postal dose validation, inter-comparison of different dosimeter/electrometers, and validity of Nd,water calibrations obtained from different calibration laboratories were analyzed to find out the extent of accuracy achievable. Nd,w factors in Gray/Coulomb calibrated at IBA, GmBH, Germany showed a mean variation of about 0.2% increase per year in three Farmer chambers, in three subsequent calibrations. Another ion chamber calibrated in different accredited laboratory (PTW, Germany) showed consistent Nd,w for 9 years period. The Strontium-90 beta check source response indicated long-term stability of the ion chambers within 1% for three chambers. Results of IAEA postal TL “dose intercomparison” for three photon beams, 6 MV (two) and 15 MV (one), agreed well within our reported doses, with mean deviation of 0.03% (SD 0.87%) (n = 9). All the chamber/electrometer calibrated by a single SSDL realized absorbed doses in water within 0.13% standard deviations. However, about 1-2% differences in absorbed dose estimates observed when dosimeters calibrated from different calibration laboratories are compared in solid phantoms. Our data therefore imply that the dosimetry level maintained for clinical use of linear accelerator photon beams are within recommended levels of accuracy, and uncertainties are within reported values. PMID:24672156

High-Dose Hook Effect in 17-Hydroxyprogesterone Assay in a Patient with 21-Hydroxylase Deficiency.

PubMed

Parlak, Mesut; Ellidağ, Hamit Yaşar; Türkkahraman, Doğa

2015-12-01

Congenital adrenal hyperplasia (CAH) describes a group of disorders characterized by enzyme defects in adrenal steroidogenesis. 21-hydroxylase deficiency (21-OHD) is the most commonly encountered form. The analysis of steroids in pediatric cases requires high-sensitivity assays. A 14-year-old Syrian girl was referred for evaluation of short stature, amenorrhea, and hirsutism. On physical examination, breast development was Tanner stage 1. She had a phallic clitoris with a single urogenital orifice. Laboratory findings revealed primary adrenal deficiency with high androgen levels and low levels of 17-hydroxyprogesterone (17-OHP), (<0.05 ng/mL) and estrogen. This unexpected result led to suspicion of a high-dose hook effect. The measurement was repeated after 1/10 dilution of serum, and a high level of 17-OHP (115.4 ng/mL) was detected with the same test-enzyme-linked immunosorbent assay (ELISA). Simple virilizing form of CAH (21-OHD) was suspected and confirmed with genetic analysis. After initiation of glucocorticoid therapy, breast development was noted along with a decrease in testosterone level and an increase in estrogen level. To our knowledge, this is the first case report of hook effect for 17-OHP immunoassay in a patient with 21-OHD. High-dose hook effect should be suspected in patients with CAH when the test results are incompatible with one another. Additionally, this case demonstrates that a high testosterone level can block aromatase activity and consequently also estrogen production and breast development.

SU-F-T-428: An Optimization-Based Commissioning Tool for Finite Size Pencil Beam Dose Calculations

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

Li, Y; Tian, Z; Song, T

Purpose: Finite size pencil beam (FSPB) algorithms are commonly used to pre-calculate the beamlet dose distribution for IMRT treatment planning. FSPB commissioning, which usually requires fine tuning of the FSPB kernel parameters, is crucial to the dose calculation accuracy and hence the plan quality. Yet due to the large number of beamlets, FSPB commissioning could be very tedious. This abstract reports an optimization-based FSPB commissioning tool we have developed in MatLab to facilitate the commissioning. Methods: A FSPB dose kernel generally contains two types of parameters: the profile parameters determining the dose kernel shape, and a 2D scaling factors accountingmore » for the longitudinal and off-axis corrections. The former were fitted using the penumbra of a reference broad beam’s dose profile with Levenberg-Marquardt algorithm. Since the dose distribution of a broad beam is simply a linear superposition of the dose kernel of each beamlet calculated with the fitted profile parameters and scaled using the scaling factors, these factors could be determined by solving an optimization problem which minimizes the discrepancies between the calculated dose of broad beams and the reference dose. Results: We have commissioned a FSPB algorithm for three linac photon beams (6MV, 15MV and 6MVFFF). Dose of four field sizes (6*6cm2, 10*10cm2, 15*15cm2 and 20*20cm2) were calculated and compared with the reference dose exported from Eclipse TPS system. For depth dose curves, the differences are less than 1% of maximum dose after maximum dose depth for most cases. For lateral dose profiles, the differences are less than 2% of central dose at inner-beam regions. The differences of the output factors are within 1% for all the three beams. Conclusion: We have developed an optimization-based commissioning tool for FSPB algorithms to facilitate the commissioning, providing sufficient accuracy of beamlet dose calculation for IMRT optimization.« less

Effects of radioactive contamination on Scots pines in the remote period after the Chernobyl accident.

PubMed

Geras'kin, Stanislav; Oudalova, Alla; Dikareva, Nina; Spiridonov, Sergey; Hinton, Thomas; Chernonog, Elena; Garnier-Laplace, Jacqueline

2011-08-01

A 6 year study of Scots pine populations inhabiting sites in the Bryansk region of Russia radioactively contaminated as a result of the Chernobyl accident is presented. In six study sites, (137)Cs activity concentrations and heavy metal content in soils, as well as (137)Cs, (90)Sr and heavy metal concentrations in cones were measured. Doses absorbed in reproduction organs of pine trees were calculated using a dosimetric model. The maximum annual dose absorbed at the most contaminated site was about 130 mGy. Occurrence of aberrant cells scored in the root meristem of germinated seeds collected from pine trees growing on radioactively contaminated territories for over 20 years significantly exceeded the reference levels during all 6 years of the study. The data suggest that cytogenetic effects occur in Scots pine populations due to the radioactive contamination. However, no consistent differences in reproductive ability were detected between the impacted and reference populations as measured by the frequency of abortive seeds. Even though the Scots pine populations have occupied radioactively contaminated territories for two decades, there were no clear indications of adaptation to the radiation, when measured by the number of aberrant cells in root meristems of seeds exposed to an additional acute dose of radiation.

SU-F-J-99: Dose Accumulation and Evaluation in Lung SBRT Among All Phases of Respiration

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

Azcona, JD; Barbes, B; Aristu, J

Purpose: To calculate the total planning dose on lung tumors (GTV) by accumulating the dose received in all respiration phases. Methods: A patient 4D planning CT (phase-binned, from a Siemens Somatom CT) was used to locate the GTV of a lung tumor in all respiratory phases with Pinnacle (v9.10). GTV contours defined in all phases were projected to the reference phase, where the ITV was defined. Centroids were calculated for all the GTV projections. No deformation or rotation was taken into account. The only GTV contour as defined in the reference phase was voxelized to track each voxel individually. Wemore » accumulated the absorbed dose in different phases on each voxel. A 3DCRT and a VMAT plan were designed on the reference phase fulfilling the ITV dosimetric requirements, using the 10MV FFF photon model from an Elekta Versa linac. ITV-to-PTV margins were set to 5mm. In-house developed MATLAB code was used for tumor voxeling and dose accumulation, assuming that the dose distribution planned in the reference phase behaved as a “dose-cloud” during patient breathing. Results: We tested the method on a patient 4DCT set of images exhibiting limited tumor motion (<5mm). For the 3DCRT plan, D95 was calculated for the GTV with motion and for the ITV, showing an agreement of 0.04%. For the VMAT plan, we calculated the D95 for every phase as if the GTV in that phase had received the whole treatment. Differences in D95 for all phases are within 1%, and estimate the potential interplay effect during delivery. Conclusion: A method for dose accumulation and assessment was developed that can compare GTV motion with ITV dosage, and estimate the potential interplay effect for VMAT plans. Work in progress includes the incorporation of deformable image registration and 4D CBCT dose calculation for dose reconstruction and assessment during treatment.« less

SU-G-TeP3-02: Determination of Geometry-Specific Backscatter Factors for Radiobiology Studies

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

Viscariello, N; Culberson, W; Lawless, M

2016-06-15

Purpose: Radiation biology research relies on an accurate radiation dose delivered to the biological target. Large field irradiations in a cabinet irradiator may use the AAPM TG-61 protocol. This relies on an air-kerma measurement and conversion to absorbed dose to water (Dw) on the surface of a water phantom using provided backscatter factors. Cell or small animal studies differ significantly from this reference geometry. This study aims to determine the impact of the lack of full scatter conditions in four representative geometries that may be used in radiobiology studies. Methods: MCNP6 was used to model the Dw on the surfacemore » of a full scatter phantom in a validated orthovoltage x-ray reference beam. Dw in a cylindrical mouse, 100 mm Petri dish, 6-well and 96-well cell culture dishes was simulated and compared to this full scatter geometry. A reference dose rate was measured using the TG-61 protocol in a cabinet irradiator. This nominal dose rate was used to irradiate TLDs in each phantom to a given dose. Doses were obtained based on TLDs calibrated in a NIST-traceable beam. Results: Compared to the full scattering conditions, the simulated dose to water in the representative geometries were found to be underestimated by 12-26%. The discrepancy was smallest with the cylindrical mouse geometry, which most closely approximates adequate lateral- and backscatter. TLDs irradiated in the mouse and petri dish phantoms using the TG-61 determined dose rate showed similarly lower values of Dw. When corrected for this discrepancy, they agreed with the predicted Dw within 5%. Conclusion: Using the TG-61 in-air protocol and given backscatter factors to determine a reference dose rate in a biological irradiator may not be appropriate given the difference in scattering conditions between irradiation and calibration. Without accounting for this, the dose rate is overestimated and is dependent on irradiation geometry.« less

Reference levels of background radioactivity for beach sands and soils in İnebolu/Kastamonu-Turkey

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

Kurnaz, Aslı, E-mail: akurnaz@kastamonu.edu.tr; Türkdoğan, Savaş, E-mail: savas-turk-dogan@hotmail.com; Hançerlioğulları, Aybaba, E-mail: aybaba@kastamonu.edu.tr

This paper presents the measurement results of environmental radioactivity levels for İnebolu district (tourist area), Kastamonu-Turkey. The radioactivity concentrations of {sup 238}U, {sup 232}Th, {sup 40}K and the fission product {sup 137}Cs in soil samples collected from 13 region surroundings of study area and in 12 beach sand samples collected from along the coast of İnebolu were determined. To evaluate the radiological hazard of the natural radioactivity, based on the measured concentrations of these radionuclides, the mean absorbed gamma dose and the annual effective dose were evaluated separately, and found to be 112.90 nGy h-1 and 138.46 µSv y-1 for soilmore » samples and 75.19 nGy h-1 and 92.22 µSv y-1 for beach sand samples, respectively. The results show that İnebolu does not have high background.« less

Reference levels of background radioactivity for beach sands and soils in İnebolu/Kastamonu-Turkey

NASA Astrophysics Data System (ADS)

Kurnaz, Aslı; Türkdoǧan, Savaş; Hançerlioǧulları, Aybaba; ćetiner, M. Atıf

2016-03-01

This paper presents the measurement results of environmental radioactivity levels for İnebolu district (tourist area), Kastamonu-Turkey. The radioactivity concentrations of 238U, 232Th, 40K and the fission product 137Cs in soil samples collected from 13 region surroundings of study area and in 12 beach sand samples collected from along the coast of İnebolu were determined. To evaluate the radiological hazard of the natural radioactivity, based on the measured concentrations of these radionuclides, the mean absorbed gamma dose and the annual effective dose were evaluated separately, and found to be 112.90 nGy h-1 and 138.46 µSv y-1 for soil samples and 75.19 nGy h-1 and 92.22 µSv y-1 for beach sand samples, respectively. The results show that İnebolu does not have high background.

Evaluation of entrance surface air kerma in pediatric chest radiography

NASA Astrophysics Data System (ADS)

Porto, L.; Lunelli, N.; Paschuk, S.; Oliveira, A.; Ferreira, J. L.; Schelin, H.; Miguel, C.; Denyak, V.; Kmiecik, C.; Tilly, J.; Khoury, H.

2014-11-01

The objective of this study was to evaluate the entrance surface air kerma in pediatric chest radiography. An evaluation of 301 radiographical examinations in anterior-posterior (AP) and posterior-anterior (PA) (166 examinations) and lateral (LAT) (135 examinations) projections was performed. The analyses were performed on patients grouped by age; the groups included ages 0-1 y, 1-5 y, 5-10 y, and 10-15 y. The entrance surface air kerma was determined with DoseCal software (Radiological Protection Center of Saint George's Hospital, London) and thermoluminescent dosimeters. Two different exposure techniques were compared. The doses received by patients who had undergone LAT examinations were 40% higher, on average, those in AP/PA examinations because of the difference in tube voltage. A large high-dose “tail” was observed for children up to 5 y old. An increase in tube potential and corresponding decrease in current lead to a significant dose reduction. The difference between the average dose values for different age ranges was not practically observed, implying that the exposure techniques are still not optimal. Exposure doses received using the higher tube voltage and lower current-time product correspond to the international diagnostic reference levels.

Paediatric x-ray examinations in Rio de Janeiro

NASA Astrophysics Data System (ADS)

Azevedo, A. C. P.; Osibote, O. A.; Boechat, M. C. B.

2006-08-01

This work presents the results of a dose survey performed for paediatric patients and carried out in two large paediatric public hospitals in Rio de Janeiro city. The entrance surface dose (ESD) and the effective dose (ED) were evaluated for chest, skull, abdomen, lumbar spine, cervical spine and pelvis in antero-posterior (AP), postero-anterior (PA) and lateral (LAT) projections. For each examination, four age groups 0-1, 1-5, 5-10 and 10-15 years were studied. The DoseCal software was used to calculate these doses. Wide variations for the same type of examination and projection have been detected. These variations were evident, in Brazil, from previous work. In spite of the present results being still preliminary, they can give an idea of what paediatric ESDs are like in Brazil. Also, with respect to the entrance surface dose, some of the results are above the reference levels, which cause high ED, as well. On the other hand, the wide range of ESD reflects the disparity of radiographic techniques and demonstrates that the ALARA principle is not being applied in Brazilian hospitals and becomes a concern in terms of public health.

Signal-to-noise ratio and dose to the lens of the eye for computed tomography examination of the brain using an automatic tube current modulation system.

PubMed

Sookpeng, Supawitoo; Butdee, Chitsanupong

2017-06-01

The study aimed to evaluate the image quality in terms of signal-to-noise ratio (SNR) and dose to the lens of the eye and the other nearby organs from the CT brain scan using an automatic tube current modulation (ATCM) system with or without CT gantry tilt is needed. An anthropomorphic phantom was scanned with different settings including use of different ATCM, fixed tube current time product (mAs) settings and degree angles of gantry tilt. Gafchromic film XR-QA2 was used to measure absorbed dose of the organs. Relative doses and SNR for the various scan settings were compared with the reference setting of the fixed 330 mAs. Average absorbed dose for the lens of the eyes varied from 8.7 to 21.7 mGy. The use of the ATCM system with the gantry tilt resulted in up to 60% decrease in the dose to the lens of the eye. SNR significantly decreased while tilting the gantry using the fixed mAs techniques, compared to that of the reference setting. However, there were no statistical significant differences for SNRs between the reference setting and all ATCM settings. Compared to the reference setting of the fixed effective mAs, using the ATCM system and appropriate tilting, the gantry resulted in a substantial decrease in the dose to the lens of the eye while preserving signal-to-noise ratio. CT brain examination should be carefully controlled to optimize dose for lens of the eye and image quality of the examination.

Exploring Radiotherapy Targeting Strategy and Dose: A Pooled Analysis of Cooperative Group Trials of Combined Modality Therapy for Stage III Non-Small Cell Lung Cancer.

PubMed

Schild, Steven E; Fan, Wen; Stinchcombe, Thomas E; Vokes, Everett E; Ramalingam, Suresh S; Bradley, Jeffrey D; Kelly, Karen; Pang, Herbert H; Wang, Xiaofei

2018-04-21

Concurrent chemoradiotherapy(CRT) is standard therapy for locally-advanced non-small-cell lung cancer(LA-NSCLC)patients. This study was performed to examine thoracic radiotherapy(TRT) parameters and their impact on patient survival. We collected Individual patient data(IPD) from 3600LA-NSCLC patients participating in 16 cooperative group trials of concurrent CRT. The primary TRT parameters examined included field design strategy(elective nodal irradiation(ENI) compared to involved field TRT(IF-TRT)), total dose, and biologically effective dose(BED). Hazard ratios(HRs) for overall survival were calculated with univariable and multivariable Cox models. TRT doses ranged from 60 to 74 Gy with most treatments administered once-daily. ENI was associated with poorer survival than IF-TRT(univariable HR,1.37;95%CI,1.24-1.51,p<0.0001;multivariable HR,1.31;95%CI,1.08-1.59,p=0.002). The median survival of the IF and ENI patients were 24 and 16 months, respectively. Patients were divided into 3 dose groups: low total dose(60 Gy), medium total dose(>60Gy-66Gy) and high total dose(>66Gy-74 Gy). With reference to the low dose group, the multivariable HR's were 1.08 for the medium dose group(95%CI=0.93-1.25) and 1.12 for the high dose group(CI=0.97-1.30).The univariate p=0.054 and multivariable p=0.17. BED was grouped as follows: low(<55.5Gy 10 ), medium(=55.5 Gy 10) , or high(>55.5 Gy 10 ). With reference to the low BED group, the HR was 1.00(95%CI=0.85-1.18) for the medium BED group and 1.10(95%CI=0.93-1.31) for the high BED group. The univariable p=0.076 and multivariable p=0.16. For LA-NSCLC patients treated with concurrent CRT, IF-TRT was associated with significantly better survival than ENI-TRT. TRT total and BED dose levels were not significantly associated with patient survival. Future progress will require research focusing on better systemic therapy and TRT. Copyright © 2018. Published by Elsevier Inc.

Effects of sub-lethal exposure of rats to the herbicide glyphosate in drinking water: glutathione transferase enzyme activities, levels of reduced glutathione and lipid peroxidation in liver, kidneys and small intestine.

PubMed

Larsen, K; Najle, R; Lifschitz, A; Virkel, G

2012-11-01

Glyphosate (GLP), the active ingredient of many weed killing formulations, is a broad spectrum herbicide compound. Wistar rats were exposed during 30 or 90 days to the highest level (0.7 mg/L) of GLP allowed in water for human consumption (US EPA, 2011) and a 10-fold higher concentration (7 mg/L). The low levels of exposure to the herbicide did not produce histomorphological changes. The production of TBARS was similar or tended to be lower compared to control animals not exposed to the herbicide. In rats exposed to GLP, increased levels of reduced glutathione (GSH) and enhanced glutathione peroxidase (GPx) activity may act as a protective mechanism against possible detrimental effects of the herbicide. Overall, this work showed certain biochemical modifications, even at 3-20-fold lower doses of GLP than the oral reference dose of 2mg/kg/day (US EPA, 1993). The toxicological significance of these findings remains to be clarified. Copyright © 2012 Elsevier B.V. All rights reserved.

Dose estimation for astronauts using dose conversion coefficients calculated with the PHITS code and the ICRP/ICRU adult reference computational phantoms.

PubMed

Sato, Tatsuhiko; Endo, Akira; Sihver, Lembit; Niita, Koji

2011-03-01

Absorbed-dose and dose-equivalent rates for astronauts were estimated by multiplying fluence-to-dose conversion coefficients in the units of Gy.cm(2) and Sv.cm(2), respectively, and cosmic-ray fluxes around spacecrafts in the unit of cm(-2) s(-1). The dose conversion coefficients employed in the calculation were evaluated using the general-purpose particle and heavy ion transport code system PHITS coupled to the male and female adult reference computational phantoms, which were released as a common ICRP/ICRU publication. The cosmic-ray fluxes inside and near to spacecrafts were also calculated by PHITS, using simplified geometries. The accuracy of the obtained absorbed-dose and dose-equivalent rates was verified by various experimental data measured both inside and outside spacecrafts. The calculations quantitatively show that the effective doses for astronauts are significantly greater than their corresponding effective dose equivalents, because of the numerical incompatibility between the radiation quality factors and the radiation weighting factors. These results demonstrate the usefulness of dose conversion coefficients in space dosimetry. © Springer-Verlag 2010

Air kerma and absorbed dose standards for reference dosimetry in brachytherapy

PubMed Central

2014-01-01

This article reviews recent developments in primary standards for the calibration of brachytherapy sources, with an emphasis on the currently most common photon-emitting radionuclides. The introduction discusses the need for reference dosimetry in brachytherapy in general. The following section focuses on the three main quantities, i.e. reference air kerma rate, air kerma strength and absorbed dose rate to water, which are currently used for the specification of brachytherapy photon sources and which can be realized with primary standards from first principles. An overview of different air kerma and absorbed dose standards, which have been independently developed by various national metrology institutes over the past two decades, is given in the next two sections. Other dosimetry techniques for brachytherapy will also be discussed. The review closes with an outlook on a possible transition from air kerma to absorbed dose to water-based calibrations for brachytherapy sources in the future. PMID:24814696

Estimation of absorbed radiation dose rates in wild rodents inhabiting a site severely contaminated by the Fukushima Dai-ichi nuclear power plant accident.

PubMed

Kubota, Yoshihisa; Takahashi, Hiroyuki; Watanabe, Yoshito; Fuma, Shoichi; Kawaguchi, Isao; Aoki, Masanari; Kubota, Masahide; Furuhata, Yoshiaki; Shigemura, Yusaku; Yamada, Fumio; Ishikawa, Takahiro; Obara, Satoshi; Yoshida, Satoshi

2015-04-01

The dose rates of radiation absorbed by wild rodents inhabiting a site severely contaminated by the Fukushima Dai-ichi Nuclear Power Plant accident were estimated. The large Japanese field mouse (Apodemus speciosus), also called the wood mouse, was the major rodent species captured in the sampling area, although other species of rodents, such as small field mice (Apodemus argenteus) and Japanese grass voles (Microtus montebelli), were also collected. The external exposure of rodents calculated from the activity concentrations of radiocesium ((134)Cs and (137)Cs) in litter and soil samples using the ERICA (Environmental Risk from Ionizing Contaminants: Assessment and Management) tool under the assumption that radionuclides existed as the infinite plane isotropic source was almost the same as those measured directly with glass dosimeters embedded in rodent abdomens. Our findings suggest that the ERICA tool is useful for estimating external dose rates to small animals inhabiting forest floors; however, the estimated dose rates showed large standard deviations. This could be an indication of the inhomogeneous distribution of radionuclides in the sampled litter and soil. There was a 50-fold difference between minimum and maximum whole-body activity concentrations measured in rodents at the time of capture. The radionuclides retained in rodents after capture decreased exponentially over time. Regression equations indicated that the biological half-life of radiocesium after capture was 3.31 d. At the time of capture, the lowest activity concentration was measured in the lung and was approximately half of the highest concentration measured in the mixture of muscle and bone. The average internal absorbed dose rate was markedly smaller than the average external dose rate (<10% of the total absorbed dose rate). The average total absorbed dose rate to wild rodents inhabiting the sampling area was estimated to be approximately 52 μGy h(-1) (1.2 mGy d(-1)), even 3 years after the accident. This dose rate exceeds 0.1-1 mGy d(-1) derived consideration reference level for Reference rat proposed by the International Commission on Radiological Protection (ICRP). Copyright © 2015 Elsevier Ltd. All rights reserved.

Systematic Review and Meta-Analysis of Early-Life Exposure to Bisphenol A and Obesity-Related Outcomes in Rodents

PubMed Central

Wassenaar, Pim Nicolaas Hubertus; Trasande, Leonardo

2017-01-01

Background: Early-life exposure to bisphenol A (BPA) has been implicated to play a role in the development of obesity. Objective: A systematic review with meta-analyses of experimental rodent studies was conducted to answer the following question: does early-life exposure to BPA affect the obesity-related outcomes body weight, fat (pad) weight, and circulating and tissue levels of triglycerides, free fatty acids (FFA), and leptin? Methods: The methodology was prespecified in a rigorous protocol using the Systematic Review Centre for Laboratory Animal Experimentation (SYRCLE) approach. Using PubMed and EMBASE, we identified 61 articles that met the inclusion criteria. The risk of bias and the methodological quality of these articles were assessed using the SYRCLE Risk of Bias tool, and a confidence-rating methodology was used to score the quality of evidence. Meta-analyses were performed using random effect models and standardized mean differences (SMDs), or, where possible, mean differences (MDs) were calculated. Results: Overall summary estimates indicated significant positive associations between BPA and fat weight [SMD=0.67 (95% CI: 0.53, 0.81)], triglycerides [SMD=0.97 (95% CI: 0.53, 1.40)], and FFA [SMD=0.86 (95% CI: 0.50, 1.22)], and a nonsignificant positive association with leptin levels [MD=0.37 (95% CI: −0.14, 0.87)] and a significant negative association with body weight were estimated [MD=−0.22 (95% CI: −0.37, −0.06)]. Subgroup analyses revealed stronger positive associations for most outcome measures in males and at doses below the current U.S. reference dose of 50μg/kg/d compared with doses above the reference dose. It should be noted that there was substantial heterogeneity across studies for all outcomes assessed and that there was insufficient information to assess risk of bias for most studies. Conclusions: Findings from our systematic review suggest that early-life exposure to BPA may increase adiposity and circulating lipid levels in rodents. https://doi.org/10.1289/EHP1233 PMID:28982642

The impact of anthropometric patient-phantom matching on organ dose: A hybrid phantom study for fluoroscopy guided interventions

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

Johnson, Perry B.; Geyer, Amy; Borrego, David

Purpose: To investigate the benefits and limitations of patient-phantom matching for determining organ dose during fluoroscopy guided interventions. Methods: In this study, 27 CT datasets representing patients of different sizes and genders were contoured and converted into patient-specific computational models. Each model was matched, based on height and weight, to computational phantoms selected from the UF hybrid patient-dependent series. In order to investigate the influence of phantom type on patient organ dose, Monte Carlo methods were used to simulate two cardiac projections (PA/left lateral) and two abdominal projections (RAO/LPO). Organ dose conversion coefficients were then calculated for each patient-specific andmore » patient-dependent phantom and also for a reference stylized and reference hybrid phantom. The coefficients were subsequently analyzed for any correlation between patient-specificity and the accuracy of the dose estimate. Accuracy was quantified by calculating an absolute percent difference using the patient-specific dose conversion coefficients as the reference. Results: Patient-phantom matching was shown most beneficial for estimating the dose to heavy patients. In these cases, the improvement over using a reference stylized phantom ranged from approximately 50% to 120% for abdominal projections and for a reference hybrid phantom from 20% to 60% for all projections. For lighter individuals, patient-phantom matching was clearly superior to using a reference stylized phantom, but not significantly better than using a reference hybrid phantom for certain fields and projections. Conclusions: The results indicate two sources of error when patients are matched with phantoms: Anatomical error, which is inherent due to differences in organ size and location, and error attributed to differences in the total soft tissue attenuation. For small patients, differences in soft tissue attenuation are minimal and are exceeded by inherent anatomical differences. For large patients, difference in soft tissue attenuation can be large. In these cases, patient-phantom matching proves most effective as differences in soft tissue attenuation are mitigated. With increasing obesity rates, overweight patients will continue to make up a growing fraction of all patients undergoing medical imaging. Thus, having phantoms that better represent this population represents a considerable improvement over previous methods. In response to this study, additional phantoms representing heavier weight percentiles will be added to the UFHADM and UFHADF patient-dependent series.« less

Bioequivalence of generic alendronate sodium tablets (70 mg) to Fosamax® tablets (70 mg) in fasting, healthy volunteers: a randomized, open-label, three-way, reference-replicated crossover study

PubMed Central

Zhang, Yifan; Chen, Xiaoyan; Tang, Yunbiao; Lu, Youming; Guo, Lixia; Zhong, Dafang

2017-01-01

Purpose The aim of this study was to evaluate the bioequivalence of a generic product 70 mg alendronate sodium tablets with the reference product Fosamax® 70 mg tablet. Materials and methods A single-center, open-label, randomized, three-period, three-sequence, reference-replicated crossover study was performed in 36 healthy Chinese male volunteers under fasting conditions. In each study period, the volunteers received a single oral dose of the generic or reference product (70 mg). Blood samples were collected at pre-dose and up to 8 h after administration. The bioequivalence of the generic product to the reference product was assessed using the US Food and Drug Administration (FDA) and European Medicines Agency (EMA) reference-scaled average bioequivalence (RSABE) methods. Results The average maximum concentrations (Cmax) of alendronic acid were 64.78±43.76, 56.62±31.95, and 60.15±37.12 ng/mL after the single dose of the generic product and the first and second doses of the reference product, respectively. The areas under the plasma concentration–time curves from time 0 to the last timepoint (AUC0–t) were 150.36±82.90, 148.15±85.97, and 167.11±110.87 h⋅ng/mL, respectively. Reference scaling was used because the within-subject standard deviations of the reference product (sWR) for Cmax and AUC0–t were all higher than the cutoff value of 0.294. The 95% upper confidence bounds were −0.16 and −0.17 for Cmax and AUC0–t, respectively, and the point estimates for the generic/reference product ratio were 1.08 and 1.00, which satisfied the RSABE acceptance criteria of the FDA. The 90% CIs for Cmax and AUC0–t were 90.35%–129.04% and 85.31%–117.15%, respectively, which were within the limits of the EMA for the bioequivalence of 69.84%–143.19% and 80.00%–125.00%. Conclusion The generic product was bioequivalent to the reference product in terms of the rate and extent of alendronate absorption after a single 70 mg oral dose under fasting conditions. PMID:28744102

Proposed diagnostic reference levels for 3 common cardiac interventional procedures in Ireland

NASA Astrophysics Data System (ADS)

D'Helft, C.; McGee, A. M.; Rainford, L. A.; Mc Fadden, S. L.; Hughes, C. M.; Winder, R. J.; Brennan, P. C.

2007-03-01

Radiation doses for 3 common types of cardiac radiological examinations where investigated: coronary angiography (CA), percutaneous coronary intervention (PCI) and pacemaker insertions (PPI). 22 cardiac imaging suites participated in the study. Radiation dose was monitored for 1804 adult patients using dose area product (DAP) meters. Operational and examination details such as cardiologist grade, patient details and examination complexity were recorded for each examination. Both intra and inter-hospital variations where demonstrated by the results. Individual patient DAP values ranged from 136-23,101cGycm2, 475-41,038cGycm2 and 45- 17,192cGycm2 for CA, PCI and PPI respectively, with third quartile values of 4,173cGycm2, 8,836cGycm2 and 2,051cGycm2. Screening times varied from 0.22-27.6mins, 1.8-98mins and 0.33-54.5mins for CA, PCI and PPI respectively.

It's All Relative: A Validation of Radiation Quality Comparison Metrics

NASA Technical Reports Server (NTRS)

Chappell, Lori J.; Milder, Caitlin M.; Elgart, S. Robin; Semones, Edward J.

2017-01-01

The difference between high-LET and low-LET radiation is quantified by a measure called relative biological effectiveness (RBE). RBE is defined as the ratio of the dose of a reference radiation to that of a test radiation to achieve the same effect level, and thus, is described either as an iso-effector dose-to-dose ratio. A single dose point is not sufficient to calculate an RBE value; therefore, studies with only one dose point usually calculate an effect-to-effect ratio. While not formally used in radiation protection, these iso-dose values may still be informative. Shuryak, et al 2017 investigated the use of an iso-dose metric termed "radiation effects ratio" (RER) and used both RBE and RER to estimate high-LET risks. To apply RBE or RER to risk prediction, the selected metric must be uniquely defined. That is, the calculated value must be consistent within a model given a constant set of constraints and assumptions, regardless of how effects are defined using statistical transformations from raw endpoint data. We first test the RBE and the RER to determine whether they are uniquely defined using transformations applied to raw data. Then, we test whether both metrics can predict heavy ion response data after simulated effect size scaling between human populations or when converting animal to human endpoints.

On-line data collection platform for national dose surveys in diagnostic and interventional radiology.

PubMed

Vassileva, J; Simeonov, F; Avramova-Cholakova, S

2015-07-01

According to the Bulgarian regulation for radiation protection at medical exposure, the National Centre of Radiobiology and Radiation Protection (NCRRP) is responsible for performing national dose surveys in diagnostic and interventional radiology and nuclear medicine and for establishing of national diagnostic reference levels (DRLs). The next national dose survey is under preparation to be performed in the period of 2015-16, with the aim to cover conventional radiography, mammography, conventional fluoroscopy, interventional and fluoroscopy guided procedures and CT. It will be performed electronically using centralised on-line data collection platform established by the NCRRP. The aim is to increase the response rate and to improve the accuracy by reducing human errors. The concept of the on-line dose data collection platform is presented. Radiological facilities are provided with a tool to determine local typical patient doses, and the NCRRP to establish national DRLs. Future work will include automatic retrieval of dose data from hospital picture archival and communicating system. The on-line data collection platform is expected to facilitate the process of dose audit and optimisation of radiological procedures in Bulgarian hospitals. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Individual external doses below the lowest reference level of 1 mSv per year five years after the 2011 Fukushima nuclear accident among all children in Soma City, Fukushima: A retrospective observational study.

PubMed

Tsubokura, Masaharu; Murakami, Michio; Nomura, Shuhei; Morita, Tomohiro; Nishikawa, Yoshitaka; Leppold, Claire; Kato, Shigeaki; Kami, Masahiro

2017-01-01

After the 2011 Fukushima Daiichi nuclear power plant accident, little information has been available on individual doses from external exposure among residents living in radioactively contaminated areas near the nuclear plant; in the present study we evaluated yearly changes in the doses from external exposure after the accident and the effects of decontamination on external exposure. This study considered all children less than 16 years of age in Soma City, Fukushima who participated in annual voluntary external exposure screening programs during the five years after the accident (n = 5,363). In total, 14,405 screening results were collected. The median participant age was eight years. The geometric mean levels of annual additional doses from external exposure attributable to the Fukushima accident, decreased each year: 0.60 mSv (range: not detectable (ND)-4.29 mSv), 0.37 mSv (range: ND-3.61 mSv), 0.22 mSv (range: ND-1.44 mSv), 0.20 mSv (range: ND-1.87 mSv), and 0.17 mSv (range: ND-0.85 mSv) in 2011, 2012, 2013, 2014, and 2015, respectively. The proportion of residents with annual additional doses from external exposure of more than 1 mSv dropped from 15.6% in 2011 to zero in 2015. Doses from external exposure decreased more rapidly than those estimated from only physical decay, even in areas without decontamination (which were halved in 395 days from November 15, 2011), presumably due to the weathering effects. While the ratios of geometric mean doses immediately after decontamination to before were slightly lower than those during the same time in areas without decontamination, annual additional doses reduced by decontamination were small (0.04-0.24 mSv in the year of immediately after decontamination was completed). The results of this study showed that the levels of external exposure among Soma residents less than 16 years of age decreased during the five years after the Fukushima Daiichi nuclear power plant accident. Decontamination had only limited and temporal effects on reducing individual external doses.

NAIRAS aircraft radiation model development, dose climatology, and initial validation.

PubMed

Mertens, Christopher J; Meier, Matthias M; Brown, Steven; Norman, Ryan B; Xu, Xiaojing

2013-10-01

[1] The Nowcast of Atmospheric Ionizing Radiation for Aviation Safety (NAIRAS) is a real-time, global, physics-based model used to assess radiation exposure to commercial aircrews and passengers. The model is a free-running physics-based model in the sense that there are no adjustment factors applied to nudge the model into agreement with measurements. The model predicts dosimetric quantities in the atmosphere from both galactic cosmic rays (GCR) and solar energetic particles, including the response of the geomagnetic field to interplanetary dynamical processes and its subsequent influence on atmospheric dose. The focus of this paper is on atmospheric GCR exposure during geomagnetically quiet conditions, with three main objectives. First, provide detailed descriptions of the NAIRAS GCR transport and dosimetry methodologies. Second, present a climatology of effective dose and ambient dose equivalent rates at typical commercial airline altitudes representative of solar cycle maximum and solar cycle minimum conditions and spanning the full range of geomagnetic cutoff rigidities. Third, conduct an initial validation of the NAIRAS model by comparing predictions of ambient dose equivalent rates with tabulated reference measurement data and recent aircraft radiation measurements taken in 2008 during the minimum between solar cycle 23 and solar cycle 24. By applying the criterion of the International Commission on Radiation Units and Measurements (ICRU) on acceptable levels of aircraft radiation dose uncertainty for ambient dose equivalent greater than or equal to an annual dose of 1 mSv, the NAIRAS model is within 25% of the measured data, which fall within the ICRU acceptable uncertainty limit of 30%. The NAIRAS model predictions of ambient dose equivalent rate are generally within 50% of the measured data for any single-point comparison. The largest differences occur at low latitudes and high cutoffs, where the radiation dose level is low. Nevertheless, analysis suggests that these single-point differences will be within 30% when a new deterministic pion-initiated electromagnetic cascade code is integrated into NAIRAS, an effort which is currently underway.

NAIRAS aircraft radiation model development, dose climatology, and initial validation

NASA Astrophysics Data System (ADS)

Mertens, Christopher J.; Meier, Matthias M.; Brown, Steven; Norman, Ryan B.; Xu, Xiaojing

2013-10-01

The Nowcast of Atmospheric Ionizing Radiation for Aviation Safety (NAIRAS) is a real-time, global, physics-based model used to assess radiation exposure to commercial aircrews and passengers. The model is a free-running physics-based model in the sense that there are no adjustment factors applied to nudge the model into agreement with measurements. The model predicts dosimetric quantities in the atmosphere from both galactic cosmic rays (GCR) and solar energetic particles, including the response of the geomagnetic field to interplanetary dynamical processes and its subsequent influence on atmospheric dose. The focus of this paper is on atmospheric GCR exposure during geomagnetically quiet conditions, with three main objectives. First, provide detailed descriptions of the NAIRAS GCR transport and dosimetry methodologies. Second, present a climatology of effective dose and ambient dose equivalent rates at typical commercial airline altitudes representative of solar cycle maximum and solar cycle minimum conditions and spanning the full range of geomagnetic cutoff rigidities. Third, conduct an initial validation of the NAIRAS model by comparing predictions of ambient dose equivalent rates with tabulated reference measurement data and recent aircraft radiation measurements taken in 2008 during the minimum between solar cycle 23 and solar cycle 24. By applying the criterion of the International Commission on Radiation Units and Measurements (ICRU) on acceptable levels of aircraft radiation dose uncertainty for ambient dose equivalent greater than or equal to an annual dose of 1 mSv, the NAIRAS model is within 25% of the measured data, which fall within the ICRU acceptable uncertainty limit of 30%. The NAIRAS model predictions of ambient dose equivalent rate are generally within 50% of the measured data for any single-point comparison. The largest differences occur at low latitudes and high cutoffs, where the radiation dose level is low. Nevertheless, analysis suggests that these single-point differences will be within 30% when a new deterministic pion-initiated electromagnetic cascade code is integrated into NAIRAS, an effort which is currently underway.

NAIRAS aircraft radiation model development, dose climatology, and initial validation

PubMed Central

Mertens, Christopher J; Meier, Matthias M; Brown, Steven; Norman, Ryan B; Xu, Xiaojing

2013-01-01

[1] The Nowcast of Atmospheric Ionizing Radiation for Aviation Safety (NAIRAS) is a real-time, global, physics-based model used to assess radiation exposure to commercial aircrews and passengers. The model is a free-running physics-based model in the sense that there are no adjustment factors applied to nudge the model into agreement with measurements. The model predicts dosimetric quantities in the atmosphere from both galactic cosmic rays (GCR) and solar energetic particles, including the response of the geomagnetic field to interplanetary dynamical processes and its subsequent influence on atmospheric dose. The focus of this paper is on atmospheric GCR exposure during geomagnetically quiet conditions, with three main objectives. First, provide detailed descriptions of the NAIRAS GCR transport and dosimetry methodologies. Second, present a climatology of effective dose and ambient dose equivalent rates at typical commercial airline altitudes representative of solar cycle maximum and solar cycle minimum conditions and spanning the full range of geomagnetic cutoff rigidities. Third, conduct an initial validation of the NAIRAS model by comparing predictions of ambient dose equivalent rates with tabulated reference measurement data and recent aircraft radiation measurements taken in 2008 during the minimum between solar cycle 23 and solar cycle 24. By applying the criterion of the International Commission on Radiation Units and Measurements (ICRU) on acceptable levels of aircraft radiation dose uncertainty for ambient dose equivalent greater than or equal to an annual dose of 1 mSv, the NAIRAS model is within 25% of the measured data, which fall within the ICRU acceptable uncertainty limit of 30%. The NAIRAS model predictions of ambient dose equivalent rate are generally within 50% of the measured data for any single-point comparison. The largest differences occur at low latitudes and high cutoffs, where the radiation dose level is low. Nevertheless, analysis suggests that these single-point differences will be within 30% when a new deterministic pion-initiated electromagnetic cascade code is integrated into NAIRAS, an effort which is currently underway. PMID:26213513

A 1-year randomized study to evaluate the effects of a dose reduction in oral contraceptives on lipids and carbohydrate metabolism: 20 microg ethinyl estradiol combined with 100 microg levonorgestrel.

PubMed

Skouby, Sven O; Endrikat, Jan; Düsterberg, Bernd; Schmidt, Werner; Gerlinger, Christoph; Wessel, Jens; Goldstein, Henri; Jespersen, Joergen

2005-02-01

To evaluate the impact on lipid and carbohydrate variables of a combined one-third ethinyl estradiol (EE)/levonorgestrel (LNG) dose reduction in oral contraceptives. In an open-label, randomized study, a dose-reduced oral contraceptive containing 20 microg EE and 100 microg LNG (20 EE/100 LNG) was compared with a reference preparation containing 30 microg EE and 150 microg LNG (30 EE/150 LNG). One-year data from 48 volunteers were obtained. We found a decrease of HDL2 cholesterol and increases of low-density lipoprotein cholesterol, very low-density lipoprotein cholesterol and total triglycerides in both treatment groups from baseline to the 13th treatment cycle. Although for four of six variables, the changes in the 20 EE group were lower compared with the 30 EE group, none of the differences between the two treatments were statistically significant. The median values for the fasting levels of insulin, C-peptide and free fatty acids slightly increased or remained unchanged while the fasting glucose levels slightly decreased after 13 treatment cycles. While the glucose area under the curve (AUC) (0-3 h) was similar in both groups during the OGTT, the insulin AUC(0-3 h) was less increased in the 20 EE/100 LNG group compared with the 30 EE/150 LNG group. None of the differences between the treatment groups for any of the carbohydrate metabolism variables were statistically significant at any time point. Both study treatments were safe and well tolerated by the volunteers. Similar effects on the lipid and carbohydrate profiles were found for both preparations. The balanced one-third EE dose reduction in this new oral contraceptive caused slightly lower, but insignificant, changes in the lipid and carbohydrate variables compared with the reference treatment.

Optimisation and establishment of diagnostic reference levels in paediatric plain radiography

NASA Astrophysics Data System (ADS)

Paulo, Graciano do Nascimento Nobre

Purpose: This study aimed to propose Diagnostic Reference Levels (DRLs) in paediatric plain radiography and to optimise the most frequent paediatric plain radiography examinations in Portugal following an analysis and evaluation of current practice. Methods and materials: Anthropometric data (weight, patient height and thickness of the irradiated anatomy) was collected from 9,935 patients referred for a radiography procedure to one of the three dedicated paediatric hospitals in Portugal. National DRLs were calculated for the three most frequent X-ray procedures at the three hospitals: chest AP/PA projection; abdomen AP projection; pelvis AP projection. Exposure factors and patient dose were collected prospectively at the clinical sites. In order to analyse the relationship between exposure factors, the use of technical features and dose, experimental tests were made using two anthropomorphic phantoms: a) CIRSTM ATOM model 705; height: 110cm, weight: 19kg and b) Kyoto kagakuTM model PBU-60; height: 165cm, weight: 50kg. After phantom data collection, an objective image analysis was performed by analysing the variation of the mean value of the standard deviation, measured with OsiriX software (Pixmeo, Switzerland). After proposing new exposure criteria, a Visual Grading Characteristic image quality evaluation was performed blindly by four paediatric radiologists, each with a minimum of 10 years of professional experience, using anatomical criteria scoring. Results: DRLs by patient weight groups have been established for the first time. ESAKP75 DRLs for both patient age and weight groups were also obtained and are described in the thesis. Significant dose reduction was achieved through the implementation of an optimisation programme: an average reduction of 41% and 18% on KAPP75 and ESAKP75, respectively for chest plain radiography; an average reduction of 58% and 53% on KAPP75 and ESAKP75, respectively for abdomen plain radiography; and an average reduction of 47% and 48% on KAPP75 and ESAKP75, respectively for pelvis plain radiography. Conclusion: Portuguese DRLs for plain radiography were obtained for paediatric plain radiography (chest AP/PA, abdomen and pelvis). Experimental phantom tests identified adequate plain radiography exposure criteria, validated by objective and subjective image quality analysis. The new exposure criteria were put into practice in one of the paediatric hospitals, by introducing an optimisation programme. The implementation of the optimisation programme allowed a significant dose reduction to paediatric patients, without compromising image quality. (Abstract shortened by ProQuest.).

SU-F-207-14: Low Contrast Detectability (LCD) at Different Diagnostic Reference Levels for Adult Abdominal CT Procedures

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

Mahmood, U; Erdi, Y

2015-06-15

Purpose Using diagnostic reference levels (DRL) to optimize CT protocols has potential to reduce radiation dose and meet regulatory requirements. However, DRL’s tend to be misconstrued as dose limits, are typically designed for specific patient populations, and are assumed to have acceptable image quality (AIQ) associated with them. To determine the image quality that is associated with established DRL’s for adult abdominal CT studies, a LCD phantom study was employed. Methods: A CT phantom (CIRS) containing three columns of 7 spherical targets, ranging from 10mm to 2.4 mm, that are 5, 10, and 20 HU below the background (HUBB) matrixmore » was scanned with a GE HD750 64 slice scanner. The phantom was scanned at the NEXT 2006 25th CTDIvol of 12 mGy, the NCRP 172 achievable dose (AD) CTDIvol of 17 mGy and 75th CTDIvol of 25 mGy and at the ACR recommended CTDIvol of 25 mGy. It was also scanned at a CTDIvol 20% greater than the AD at 20 mGy and the ACR maximum threshold of 30 mGy. Results: At the NEXT 2006 25th percentile CTDIvol of 12 mGy, a 6.3 mm low contrast lesion was detectable in the 20 HUBB; 6.3 mm in the 10 HUBB and 10 mm in the 5 HUBB column. Increasing the CTDIvol to the NCRP 172 AD of 17 mGy, an additional 4.8 mm lesion was visualized in the 20 HUBB column. At 20 mGy, an additional 4.8 mm lesion was detectable in the 10 HUBB column. No further lesions were visible between 20 and 30 mGy. However, conspicuity of all lesions increased with each additional step up in CTDI. Conclusion: Optimizing radiation dose to achieve AIQ is a critical aspect of any dose optimization committee. Hence, judicious monitoring of radiation exposure to patients has to be balanced with diagnostic image quality.« less

Patient Dose During Carotid Artery Stenting With Embolic-Protection Devices: Evaluation With Radiochromic Films and Related Diagnostic Reference Levels According to Factors Influencing the Procedure

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

D'Ercole, Loredana, E-mail: l.dercole@smatteo.pv.it; Quaretti, Pietro; Cionfoli, Nicola

2013-04-15

To measure the maximum entrance skin dose (MESD) on patients undergoing carotid artery stenting (CAS) using embolic-protection devices, to analyze the dependence of dose and exposure parameters on anatomical, clinical, and technical factors affecting the procedure complexity, to obtain some local diagnostic reference levels (DRLs), and to evaluate whether overcoming DRLs is related to procedure complexity. MESD were evaluated with radiochromic films in 31 patients (mean age 72 {+-} 7 years). Five of 33 (15 %) procedures used proximal EPD, and 28 of 33 (85 %) procedures used distal EPD. Local DRLs were derived from the recorded exposure parameters inmore » 93 patients (65 men and 28 women, mean age 73 {+-} 9 years) undergoing 96 CAS with proximal (33 %) or distal (67 %) EPD. Four bilateral lesions were included. MESD values (mean 0.96 {+-} 0.42 Gy) were <2 Gy without relevant dependence on procedure complexity. Local DRL values for kerma area product (KAP), fluoroscopy time (FT), and number of frames (N{sub FR}) were 269 Gy cm{sup 2}, 28 minutes, and 251, respectively. Only simultaneous bilateral treatment was associated with KAP (odds ratio [OR] 10.14, 95 % confidence interval [CI] 1-102.7, p < 0.05) and N{sub FR} overexposures (OR 10.8, 95 % CI 1.1-109.5, p < 0.05). Type I aortic arch decreased the risk of FT overexposure (OR 0.4, 95 % CI 0.1-0.9, p = 0.042), and stenosis {>=} 90 % increased the risk of N{sub FR} overexposure (OR 2.8, 95 % CI 1.1-7.4, p = 0.040). At multivariable analysis, stenosis {>=} 90 % (OR 2.8, 95 % CI 1.1-7.4, p = 0.040) and bilateral treatment (OR 10.8, 95 % CI 1.1-109.5, p = 0.027) were associated with overexposure for two or more parameters. Skin doses are not problematic in CAS with EPD because these procedures rarely lead to doses >2 Gy.« less

Z-Index Parameterization for Volumetric CT Image Reconstruction via 3-D Dictionary Learning.

PubMed

Bai, Ti; Yan, Hao; Jia, Xun; Jiang, Steve; Wang, Ge; Mou, Xuanqin

2017-12-01

Despite the rapid developments of X-ray cone-beam CT (CBCT), image noise still remains a major issue for the low dose CBCT. To suppress the noise effectively while retain the structures well for low dose CBCT image, in this paper, a sparse constraint based on the 3-D dictionary is incorporated into a regularized iterative reconstruction framework, defining the 3-D dictionary learning (3-DDL) method. In addition, by analyzing the sparsity level curve associated with different regularization parameters, a new adaptive parameter selection strategy is proposed to facilitate our 3-DDL method. To justify the proposed method, we first analyze the distributions of the representation coefficients associated with the 3-D dictionary and the conventional 2-D dictionary to compare their efficiencies in representing volumetric images. Then, multiple real data experiments are conducted for performance validation. Based on these results, we found: 1) the 3-D dictionary-based sparse coefficients have three orders narrower Laplacian distribution compared with the 2-D dictionary, suggesting the higher representation efficiencies of the 3-D dictionary; 2) the sparsity level curve demonstrates a clear Z-shape, and hence referred to as Z-curve, in this paper; 3) the parameter associated with the maximum curvature point of the Z-curve suggests a nice parameter choice, which could be adaptively located with the proposed Z-index parameterization (ZIP) method; 4) the proposed 3-DDL algorithm equipped with the ZIP method could deliver reconstructions with the lowest root mean squared errors and the highest structural similarity index compared with the competing methods; 5) similar noise performance as the regular dose FDK reconstruction regarding the standard deviation metric could be achieved with the proposed method using (1/2)/(1/4)/(1/8) dose level projections. The contrast-noise ratio is improved by ~2.5/3.5 times with respect to two different cases under the (1/8) dose level compared with the low dose FDK reconstruction. The proposed method is expected to reduce the radiation dose by a factor of 8 for CBCT, considering the voted strongly discriminated low contrast tissues.

Validity of linear measurements of the jaws using ultralow-dose MDCT and the iterative techniques of ASIR and MBIR.

PubMed

Al-Ekrish, Asma'a A; Al-Shawaf, Reema; Schullian, Peter; Al-Sadhan, Ra'ed; Hörmann, Romed; Widmann, Gerlig

2016-10-01

To assess the comparability of linear measurements of dental implant sites recorded from multidetector computed tomography (MDCT) images obtained using standard-dose filtered backprojection (FBP) technique with those from various ultralow doses combined with FBP, adaptive statistical iterative reconstruction (ASIR), and model-based iterative reconstruction (MBIR) techniques. The results of the study may contribute to MDCT dose optimization for dental implant site imaging. MDCT scans of two cadavers were acquired using a standard reference protocol and four ultralow-dose test protocols (TP). The volume CT dose index of the different dose protocols ranged from a maximum of 30.48-36.71 mGy to a minimum of 0.44-0.53 mGy. All scans were reconstructed using FBP, ASIR-50, ASIR-100, and MBIR, and either a bone or standard reconstruction kernel. Linear measurements were recorded from standardized images of the jaws by two examiners. Intra- and inter-examiner reliability of the measurements were analyzed using Cronbach's alpha and inter-item correlation. Agreement between the measurements obtained with the reference-dose/FBP protocol and each of the test protocols was determined with Bland-Altman plots and linear regression. Statistical significance was set at a P-value of 0.05. No systematic variation was found between the linear measurements obtained with the reference protocol and the other imaging protocols. The only exceptions were TP3/ASIR-50 (bone kernel) and TP4/ASIR-100 (bone and standard kernels). The mean measurement differences between these three protocols and the reference protocol were within ±0.1 mm, with the 95 % confidence interval limits being within the range of ±1.15 mm. A nearly 97.5 % reduction in dose did not significantly affect the height and width measurements of edentulous jaws regardless of the reconstruction algorithm used.

A 2D ion chamber array audit of wedged and asymmetric fields in an inhomogeneous lung phantom

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

Lye, Jessica; Dunn, Leon, E-mail: leon.dunn@arpansa.gov.au; Alves, Andrew

Purpose: The Australian Clinical Dosimetry Service (ACDS) has implemented a new method of a nonreference condition Level II type dosimetric audit of radiotherapy services to increase measurement accuracy and patient safety within Australia. The aim of this work is to describe the methodology, tolerances, and outcomes from the new audit. Methods: The ACDS Level II audit measures the dose delivered in 2D planes using an ionization chamber based array positioned at multiple depths. Measurements are made in rectilinear homogeneous and inhomogeneous phantoms composed of slabs of solid water and lung. Computer generated computed tomography data sets of the rectilinear phantomsmore » are supplied to the facility prior to audit for planning of a range of cases including reference fields, asymmetric fields, and wedged fields. The audit assesses 3D planning with 6 MV photons with a static (zero degree) gantry. Scoring is performed using local dose differences between the planned and measured dose within 80% of the field width. The overall audit result is determined by the maximum dose difference over all scoring points, cases, and planes. Pass (Optimal Level) is defined as maximum dose difference ≤3.3%, Pass (Action Level) is ≤5.0%, and Fail (Out of Tolerance) is >5.0%. Results: At close of 2013, the ACDS had performed 24 Level II audits. 63% of the audits passed, 33% failed, and the remaining audit was not assessable. Of the 15 audits that passed, 3 were at Pass (Action Level). The high fail rate is largely due to a systemic issue with modeling asymmetric 60° wedges which caused a delivered overdose of 5%–8%. Conclusions: The ACDS has implemented a nonreference condition Level II type audit, based on ion chamber 2D array measurements in an inhomogeneous slab phantom. The powerful diagnostic ability of this audit has allowed the ACDS to rigorously test the treatment planning systems implemented in Australian radiotherapy facilities. Recommendations from audits have led to facilities modifying clinical practice and changing planning protocols.« less

Hair cortisol measurement in mitotane-treated adrenocortical cancer patients.

PubMed

Manenschijn, L; Quinkler, M; van Rossum, E F C

2014-04-01

The only approved drug for the treatment of adrenocortical cancer (ACC) is mitotane. Mitotane is adrenolytic and therefore, hydrocortisone replacement therapy is necessary. Since mitotane increases cortisol binding globulin (CBG) and induces CYP3A4 activity, high doses of hydrocortisone are thought to be required. Evaluation of hydrocortisone therapy in mitotane-treated patients has been difficult since there is no good marker to evaluate hydrocortisone therapy. Measurement of cortisol in scalp hair is a novel method that offers the opportunity to measure long-term cortisol levels. Our aim was to evaluate whether hair cortisol measurements could be useful in evaluating recent hydrocortisone treatment in mitotane-treated ACC patients. Hair cortisol levels were measured in 15 mitotane-treated ACC patients on hydrocortisone substitution and 96 healthy individuals. Cortisol levels were measured in 3 cm hair segments, corresponding to a period of 3 months. Hair cortisol levels were higher in ACC patients compared to healthy individuals (p<0.0001). Seven ACC patients (47%) had hair cortisol levels above the reference range. None of the patients had hair cortisol levels below normal. In contrast to hydrocortisone doses (β=0.03, p=0.93), hair cortisol levels were associated with BMI (β=0.53, p=0.042). There was no correlation between hair cortisol levels and hydrocortisone doses (β=0.41, p=0.13). Almost half of the ACC patients had high hair cortisol levels, suggesting long-term over-substitution of hydrocortisone in some of the patients, whereas none of the patients was under-substituted. Hair cortisol measurements might be useful in long-term monitoring hydrocortisone treatment in mitotane-treated ACC patients. © Georg Thieme Verlag KG Stuttgart · New York.

Four-Week Repeated Intravenous Dose Toxicity and Toxicokinetic Study of TS-DP2, a Novel Human Granulocyte Colony Stimulating Factor in Rats.

PubMed

Lee, JooBuom; Lee, Kyungsun; Choe, Keunbum; Jung, Hyunseob; Cho, Hyunseok; Choi, Kiseok; Kim, Taegon; Kim, Seojin; Lee, Hyeong-Seok; Cha, Mi-Jin; Song, Si-Whan; Lee, Chul Kyu; Chun, Gie-Taek

2015-12-01

TS-DP2 is a recombinant human granulocyte colony stimulating factor (rhG-CSF) manufactured by TS Corporation. We conducted a four-week study of TS-DP2 (test article) in repeated intravenous doses in male and female Sprague-Dawley (SD) rats. Lenograstim was used as a reference article and was administered intravenously at a dose of 1000 μg/kg/day. Rats received TS-DP2 intravenously at doses of 250, 500, and 1000 μg/kg/day once daily for 4 weeks, and evaluated following a 2-week recovery period. Edema in the hind limbs and loss of mean body weight and body weight gain were observed in both the highest dose group of TS-DP2 and the lenograstim group in male rats. Fibro-osseous lesions were observed in the lenograstim group in both sexes, and at all groups of TS-DP2 in males, and at doses of TS-DP2 500 μg/kg/day and higher in females. The lesion was considered a toxicological change. Therefore, bone is the primary toxicological target of TS-DP2. The lowest observed adverse effect level (LOAEL) in males was 250 μg/kg/day, and no observed adverse effect level (NOAEL) in females was 250 μg/kg/day in this study. In the toxicokinetic study, the serum concentrations of G-CSF were maintained until 8 hr after administration. The systemic exposures (AUC0-24h and C0) were not markedly different between male and female rats, between the administration periods, or between TS-DP2 and lenograstim. In conclusion, TS-DP2 shows toxicological similarity to lenograstim over 4-weeks of repeated doses in rats.

Four-Week Repeated Intravenous Dose Toxicity and Toxicokinetic Study of TS-DP2, a Novel Human Granulocyte Colony Stimulating Factor in Rats

PubMed Central

Lee, JooBuom; Lee, Kyungsun; Choe, Keunbum; Jung, Hyunseob; Cho, Hyunseok; Choi, Kiseok; Kim, Taegon; Kim, Seojin; Lee, Hyeong-Seok; Cha, Mi-Jin; Song, Si-Whan; Lee, Chul Kyu; Chun, Gie-Taek

2015-01-01

TS-DP2 is a recombinant human granulocyte colony stimulating factor (rhG-CSF) manufactured by TS Corporation. We conducted a four-week study of TS-DP2 (test article) in repeated intravenous doses in male and female Sprague-Dawley (SD) rats. Lenograstim was used as a reference article and was administered intravenously at a dose of 1000 μg/kg/day. Rats received TS-DP2 intravenously at doses of 250, 500, and 1000 μg/kg/day once daily for 4 weeks, and evaluated following a 2-week recovery period. Edema in the hind limbs and loss of mean body weight and body weight gain were observed in both the highest dose group of TS-DP2 and the lenograstim group in male rats. Fibro-osseous lesions were observed in the lenograstim group in both sexes, and at all groups of TS-DP2 in males, and at doses of TS-DP2 500 μg/kg/day and higher in females. The lesion was considered a toxicological change. Therefore, bone is the primary toxicological target of TS-DP2. The lowest observed adverse effect level (LOAEL) in males was 250 μg/kg/day, and no observed adverse effect level (NOAEL) in females was 250 μg/kg/day in this study. In the toxicokinetic study, the serum concentrations of G-CSF were maintained until 8 hr after administration. The systemic exposures (AUC0-24h and C0) were not markedly different between male and female rats, between the administration periods, or between TS-DP2 and lenograstim. In conclusion, TS-DP2 shows toxicological similarity to lenograstim over 4-weeks of repeated doses in rats. PMID:26877840

Half-Fan-Based Intensity-Weighted Region-of-Interest Imaging for Low-Dose Cone-Beam CT in Image-Guided Radiation Therapy.

PubMed

Yoo, Boyeol; Son, Kihong; Pua, Rizza; Kim, Jinsung; Solodov, Alexander; Cho, Seungryong

2016-10-01

With the increased use of computed tomography (CT) in clinics, dose reduction is the most important feature people seek when considering new CT techniques or applications. We developed an intensity-weighted region-of-interest (IWROI) imaging method in an exact half-fan geometry to reduce the imaging radiation dose to patients in cone-beam CT (CBCT) for image-guided radiation therapy (IGRT). While dose reduction is highly desirable, preserving the high-quality images of the ROI is also important for target localization in IGRT. An intensity-weighting (IW) filter made of copper was mounted in place of a bowtie filter on the X-ray tube unit of an on-board imager (OBI) system such that the filter can substantially reduce radiation exposure to the outer ROI. In addition to mounting the IW filter, the lead-blade collimation of the OBI was adjusted to produce an exact half-fan scanning geometry for a further reduction of the radiation dose. The chord-based rebinned backprojection-filtration (BPF) algorithm in circular CBCT was implemented for image reconstruction, and a humanoid pelvis phantom was used for the IWROI imaging experiment. The IWROI image of the phantom was successfully reconstructed after beam-quality correction, and it was registered to the reference image within an acceptable level of tolerance. Dosimetric measurements revealed that the dose is reduced by approximately 61% in the inner ROI and by 73% in the outer ROI compared to the conventional bowtie filter-based half-fan scan. The IWROI method substantially reduces the imaging radiation dose and provides reconstructed images with an acceptable level of quality for patient setup and target localization. The proposed half-fan-based IWROI imaging technique can add a valuable option to CBCT in IGRT applications.

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

Altazi, B; Fernandez, D; Zhang, G

Purpose: Site-specific investigations of the role of Radiomics in cancer diagnosis and therapy are needed. We report of the reproducibility of quantitative image features over different discrete voxel levels in PET/CT images of cervical cancer. Methods: Our dataset consisted of the pretreatment PET/CT scans from a cohort of 76 patients diagnosed with cervical cancer, FIGO stage IB-IVA, age range 31–76 years, treated with external beam radiation therapy to a dose range between 45–50.4 Gy (median dose: 45 Gy), concurrent cisplatin chemotherapy and MRI-based Brachytherapy to a dose of 20–30 Gy (median total dose: 28 Gy). Two board certified radiation oncologistsmore » delineated Metabolic Tumor volume (MTV) for each patient. Radiomics features were extracted based on 32, 64, 128 and 256 discretization levels (DL). The 64 level was chosen to be the reference DL. Features were calculated based on Co-occurrence (COM), Gray Level Size Zone (GLSZM) and Run-Length (RLM) matrices. Mean Percentage Differences (Δ) of features for discrete levels were determined. Normality distribution of Δ was tested using Kolomogorov - Smirnov test. Bland-Altman test was used to investigate differences between feature values measured on different DL. The mean, standard deviation and upper/lower value limits for each pair of DL were calculated. Interclass Correlation Coefficient (ICC) analysis was performed to examine the reliability of repeated measures within the context of the test re-test format. Results: 3 global and 5 regional features out of 48 features showed distribution not significantly different from a normal one. The reproducible features passed the normality test. Only 5 reproducible results were reliable, ICC range 0.7 – 0.99. Conclusion: Most of the radiomics features tested showed sensitivity to voxel level discretization between (32 – 256). Only 4 GLSZM, 3 COM and 1 RLM showed insensitivity towards mentioned discrete levels.« less

Medical imaging dose optimisation from ground up: expert opinion of an international summit.

PubMed

Samei, Ehsan; Järvinen, Hannu; Kortesniemi, Mika; Simantirakis, George; Goh, Charles; Wallace, Anthony; Vano, Eliseo; Bejan, Adrian; Rehani, Madan; Vassileva, Jenia

2018-05-17

As in any medical intervention, there is either a known or an anticipated benefit to the patient from undergoing a medical imaging procedure. This benefit is generally significant, as demonstrated by the manner in which medical imaging has transformed clinical medicine. At the same time, when it comes to imaging that deploys ionising radiation, there is a potential associated risk from radiation. Radiation risk has been recognised as a key liability in the practice of medical imaging, creating a motivation for radiation dose optimisation. The level of radiation dose and risk in imaging varies but is generally low. Thus, from the epidemiological perspective, this makes the estimation of the precise level of associated risk highly uncertain. However, in spite of the low magnitude and high uncertainty of this risk, its possibility cannot easily be refuted. Therefore, given the moral obligation of healthcare providers, 'first, do no harm,' there is an ethical obligation to mitigate this risk. Precisely how to achieve this goal scientifically and practically within a coherent system has been an open question. To address this need, in 2016, the International Atomic Energy Agency (IAEA) organised a summit to clarify the role of Diagnostic Reference Levels to optimise imaging dose, summarised into an initial report (Järvinen et al 2017 Journal of Medical Imaging 4 031214). Through a consensus building exercise, the summit further concluded that the imaging optimisation goal goes beyond dose alone, and should include image quality as a means to include both the benefit and the safety of the exam. The present, second report details the deliberation of the summit on imaging optimisation.

NCICT: a computational solution to estimate organ doses for pediatric and adult patients undergoing CT scans.

PubMed

Lee, Choonsik; Kim, Kwang Pyo; Bolch, Wesley E; Moroz, Brian E; Folio, Les

2015-12-01

We developed computational methods and tools to assess organ doses for pediatric and adult patients undergoing computed tomography (CT) examinations. We used the International Commission on Radiological Protection (ICRP) reference pediatric and adult phantoms combined with the Monte Carlo simulation of a reference CT scanner to establish comprehensive organ dose coefficients (DC), organ absorbed dose per unit volumetric CT Dose Index (CTDIvol) (mGy/mGy). We also developed methods to estimate organ doses with tube current modulation techniques and size specific dose estimates. A graphical user interface was designed to obtain user input of patient- and scan-specific parameters, and to calculate and display organ doses. A batch calculation routine was also integrated into the program to automatically calculate organ doses for a large number of patients. We entitled the computer program, National Cancer Institute dosimetry system for CT(NCICT). We compared our dose coefficients with those from CT-Expo, and evaluated the performance of our program using CT patient data. Our pediatric DCs show good agreements of organ dose estimation with those from CT-Expo except for thyroid. Our results support that the adult phantom in CT-Expo seems to represent a pediatric individual between 10 and 15 years rather than an adult. The comparison of CTDIvol values between NCICT and dose pages from 10 selected CT scans shows good agreements less than 12% except for two cases (up to 20%). The organ dose comparison between mean and modulated mAs shows that mean mAs-based calculation significantly overestimates dose (up to 2.4-fold) to the organs in close proximity to lungs in chest and chest-abdomen-pelvis scans. Our program provides more realistic anatomy based on the ICRP reference phantoms, higher age resolution, the most up-to-date bone marrow dosimetry, and several convenient features compared to previous tools. The NCICT will be available for research purpose in the near future.

Effects of reduced natural background radiation on Drosophila melanogaster growth and development as revealed by the FLYINGLOW program.

PubMed

Morciano, Patrizia; Iorio, Roberto; Iovino, Daniela; Cipressa, Francesca; Esposito, Giuseppe; Porrazzo, Antonella; Satta, Luigi; Alesse, Edoardo; Tabocchini, Maria Antonella; Cenci, Giovanni

2018-01-01

Natural background radiation of Earth and cosmic rays played a relevant role during the evolution of living organisms. However, how chronic low doses of radiation can affect biological processes is still unclear. Previous data have indicated that cells grown at the Gran Sasso Underground Laboratory (LNGS, L'Aquila) of National Institute of Nuclear Physics (INFN) of Italy, where the dose rate of cosmic rays and neutrons is significantly reduced with respect to the external environment, elicited an impaired response against endogenous damage as compared to cells grown outside LNGS. This suggests that environmental radiation contributes to the development of defense mechanisms at cellular level. To further understand how environmental radiation affects metabolism of living organisms, we have recently launched the FLYINGLOW program that aims at exploiting Drosophila melanogaster as a model for evaluating the effects of low doses/dose rates of radiation at the organismal level. Here, we will present a comparative data set on lifespan, motility and fertility from different Drosophila strains grown in parallel at LNGS and in a reference laboratory at the University of L'Aquila. Our data suggest the reduced radiation environment can influence Drosophila development and, depending on the genetic background, may affect viability for several generations even when flies are moved back to normal background radiation. As flies are considered a valuable model for human biology, our results might shed some light on understanding the effect of low dose radiation also in humans. © 2017 Wiley Periodicals, Inc.

Development of candidate reference materials for the measurement of lead in bone

PubMed Central

Hetter, Katherine M.; Bellis, David J.; Geraghty, Ciaran; Todd, Andrew C.; Parsons, Patrick J.

2010-01-01

The production of modest quantities of candidate bone lead (Pb) reference materials is described, and an optimized production procedure is presented. The reference materials were developed to enable an assessment of the interlaboratory agreement of laboratories measuring Pb in bone; method validation; and for calibration of solid sampling techniques such as laser ablation ICP-MS. Long bones obtained from Pb-dosed and undosed animals were selected to produce four different pools of a candidate powdered bone reference material. The Pb concentrations of these pools reflect both environmental and occupational exposure levels in humans. The animal bones were harvested post mortem, cleaned, defatted, and broken into pieces using the brittle fracture technique at liquid nitrogen temperature. The bone pieces were then ground in a knife mill to produce fragments of 2-mm size. These were further ground in an ultra-centrifugal mill, resulting in finely powdered bone material that was homogenized and then sampled-scooped into vials. Testing for contamination and homogeneity was performed via instrumental methods of analysis. PMID:18421443

Risk assessment of buckwheat flour contaminated by thorn-apple (Datura stramonium L.) alkaloids: a case study from Slovenia.

PubMed

Perharič, Lucija; Koželj, Gordana; Družina, Branko; Stanovnik, Lovro

2013-01-01

In Slovenia, a mass poisoning incident involving 73 consumers with symptoms such as dry mouth, hot red skin, blurred vision, tachycardia, urinary retention, ataxia, speech disturbance, disorientation and visual hallucinations occurred in 2003. In all cases, consumers had eaten buckwheat flour food products within the last few hours. Investigations by responsible authorities identified the contamination of a range of buckwheat food products with thorn-apple (Datura stramonium L.) seeds containing toxic alkaloids, atropine and scopolamine. To ensure the safe consumption of buckwheat food products, we carried out risk characterisation and proposed provisional maximum residue levels (MRLs) of atropine and scopolamine mixture in buckwheat flour. In the absence of critical "no observed adverse effect levels" for atropine and scopolamine, we based our estimation of the acute reference doses on the lowest recommended therapeutic doses. Taking into account the additive effect of the two alkaloids, we calculated acute reference doses of the mixture, that is 0.05 µg/kg of body mass for atropine and 0.03 µg/kg of body mass for scopolamine. MRLs for atropine and scopolamine mixture in buckwheat flour were estimated in a worst-case scenario, that is consumption of 100 g of flour by a child weighing 10 kg and taking into account a range of atropine/scopolamine ratio in implicated food products, that is 0.85-3.3. We proposed the national MRLs for atropine/scopolamine mixture in buckwheat food products: 4.0 µg/kg (atropine) and 2.0 µg/kg(scopolamine). However, in view of the large variability in the alkaloid content, depending on the origin of the Datura, we propose that risk assessment should be carried out on a case-by-case basis, taking into account the ratio between atropine and scopolamine content in a particular sample.

Assessment of occupational exposure in a granite quarry and processing factory.

PubMed

Tejado, J J; Guillén, J; Baeza, A

2016-09-01

Workers in the granite industry face an occupational hazard: silicosis due to the crystalline silica present in inhalable dust. As granite can also present a variable, and occasionally significant, content of naturally occurring radionuclides, they may also face a radiological hazard. In order to assess the risk, a granite industry with a quarry and processing factory was selected to assess the occupational exposure. Three main potential pathways were observed: external irradiation, inhalation of granite dust, and radon exposure. The external dose rate was similar to that in a nearby farming area. A slight increment (0.016-0.076 mSv yr -1 ) was observed in the quarry and stockpile, due to quarry faces and granite blocks. The effective dose due to granite dust inhalation was 0.182  ±  0.009 mSv yr -1 in the worst case scenario (3 mg m -3 dust load in air and no use of filter masks). Thus, the mean value of the effective dose from these two pathways was 0.26 mSv yr -1 , lower than the reference level of 1 mSv yr -1 for the general population. The annual mean value of radon concentration in the indoor air was 33 Bq m -3 . However, during granite processing works the radon concentration can increase up to 216 Bq m -3 , due to mechanical operations (sawing, polishing, sanding, etc). This radon concentration was below the 600 Bq m -3 reference level for action in working places. Therefore, workers in this granite factory face no significant additional radiological exposure, and no-one needs to be designated as occupationally exposed and subject to individual dosimetry.

Phthalates in dormitory and house dust of northern Chinese cities: Occurrence, human exposure, and risk assessment.

PubMed

Li, Hai-Ling; Song, Wei-Wei; Zhang, Zi-Feng; Ma, Wan-Li; Gao, Chong-Jing; Li, Jia; Huo, Chun-Yan; Mohammed, Mohammed O A; Liu, Li-Yan; Kannan, Kurunthachalam; Li, Yi-Fan

2016-09-15

Phthalates are widely used chemicals in household products, which severely affect human health. However, there were limited studies emphasized on young adults' exposure to phthalates in dormitories. In this study, seven phthalates were extracted from indoor dust that collected in university dormitories in Harbin, Shenyang, and Baoding, in the north of China. Dust samples were also collected in houses in Harbin for comparison. The total concentrations of phthalates in dormitory dust in Harbin and Shenyang samples were significantly higher than those in Baoding samples. The total geometric mean concentration of phthalates in dormitory dust in Harbin was lower than in house dust. Di-(2-ethylhexyl) phthalate (DEHP) was the most abundant phthalate in both dormitory and house dust. The daily intakes of the total phthalates, carcinogenic risk (CR) of DEHP, hazard index (HI) of di-isobutyl phthalate (DiBP), dibutyl phthalate (DBP), and DEHP were estimated, the median values for all students in dormitories were lower than adults who live in the houses. Monte Carlo simulation was applied to predict the human exposure risk of phthalates. HI of DiBP, DBP, and DEHP was predicted according to the reference doses (RfD) provided by the United States Environmental Protection Agency (U.S.EPA) and the reference doses for anti-androgenicity (RfD AA) developed by Kortenkamp and Faust. The results indicated that the risks of some students had exceeded the limitation, however, the measured results were not exceeded the limitation. Risk quotients (RQ) of DEHP were predicted based on China specific No Significant Risk Level (NSRL) and Maximum Allowable Dose Level (MADL). The predicted results of CR and RQ of DEHP suggested that DEHP could pose a health risk through intake of indoor dust. Copyright © 2016 Elsevier B.V. All rights reserved.

Changes in radiation dose with variations in human anatomy: moderately and severely obese adults.

PubMed

Clark, Landon D; Stabin, Michael G; Fernald, Michael J; Brill, Aaron B

2010-06-01

The phantoms used in standardized dose assessment are based on a median (i.e., 50th percentile) individual of a large population, for example, adult males or females or children of a particular age. Here we describe phantoms that model instead the influence of obesity on specific absorbed fractions (SAFs) and dose factors in adults. The literature was reviewed to evaluate how individual organ sizes change with variations in body weight in mildly and severely obese adult men and women. On the basis of the literature evaluation, changes were made to our deformable reference adult male and female total-body models. Monte Carlo simulations of radiation transport were performed. SAFs for photons were generated for mildly and severely obese adults, and comparisons were made to the reference (50th) percentile SAF values. SAFs studied between the obese phantoms and the 50th percentile reference phantoms were not significantly different from the reference 50th percentile individual, with the exception of intestines irradiating some abdominal organs, because of an increase in separation between folds caused by an increase in mesenteric adipose deposits. Some low-energy values for certain organ pairs were different, possibly due only to the statistical variability of the data at these low energies. The effect of obesity on dose calculations for internal emitters is minor and may be neglected in the routine use of standardized dose estimates.

Calculation of conversion coefficients using Chinese adult reference phantoms for air submersion and ground contamination.

PubMed

Lu, Wei; Qiu, Rui; Wu, Zhen; Li, Chunyan; Yang, Bo; Liu, Huan; Ren, Li; Li, Junli

2017-03-21

The effective and organ equivalent dose coefficients have been widely used to provide assessment of doses received by adult members of the public and by workers exposed to environmental radiation from nuclear facilities under normal or accidental situations. Advancements in phantom types, weighting factors, decay data, etc, have led to the publication of newer results in this regard. This paper presents a new set of conversion coefficients for air submersion and ground contamination (with the use of Geant4) for photons from 15 keV to 10 MeV using the Chinese and International Commission on Radiological Protection (ICRP) adult reference male and female phantoms. The radiation fields, except for energy spectrum at low energies, were validated by the data obtained from the Monte Carlo code YURI. The effective dose coefficients of monoenergetic photons, obtained for the ICRP adult reference phantoms, agree well with recently published data for air submersion and ground contamination with a plane source at a depth of 0.5 g cm -2 in soil, but an average difference of 36.5% is observed for ground surface contamination with the abovementioned radiation field. The average differences in organ equivalent dose coefficients between the Chinese and the ICRP adult reference phantoms are within 6% for most organs, but noticeable differences of up to 70% or even higher are found at photon energies below 30 keV under air submersion. The effective dose coefficients obtained with the Chinese adult reference phantoms are greater than those of the ICRP adult reference phantoms above 30 keV and 0.5 MeV for ground contamination and air submersion, respectively; the average differences from the Chinese adult reference phantoms are about 3.6% and 0.4% in the whole energy range with maximum differences of 31.8% and 27.6% at 15 keV for air submersion and ground contamination respectively. These differences are attributed to anatomical discrepancies in overlying tissue mass of an individual organ and the body mass between the Chinese and the ICRP adult reference phantoms. These monoenergetic photon conversion coefficients are subsequently used to evaluate radionuclides with decay data from ICRP publication 107.

Calculation of conversion coefficients using Chinese adult reference phantoms for air submersion and ground contamination

NASA Astrophysics Data System (ADS)

Lu, Wei; Qiu, Rui; Wu, Zhen; Li, Chunyan; Yang, Bo; Liu, Huan; Ren, Li; Li, Junli

2017-03-01

The effective and organ equivalent dose coefficients have been widely used to provide assessment of doses received by adult members of the public and by workers exposed to environmental radiation from nuclear facilities under normal or accidental situations. Advancements in phantom types, weighting factors, decay data, etc, have led to the publication of newer results in this regard. This paper presents a new set of conversion coefficients for air submersion and ground contamination (with the use of Geant4) for photons from 15 keV to 10 MeV using the Chinese and International Commission on Radiological Protection (ICRP) adult reference male and female phantoms. The radiation fields, except for energy spectrum at low energies, were validated by the data obtained from the Monte Carlo code YURI. The effective dose coefficients of monoenergetic photons, obtained for the ICRP adult reference phantoms, agree well with recently published data for air submersion and ground contamination with a plane source at a depth of 0.5 g cm-2 in soil, but an average difference of 36.5% is observed for ground surface contamination with the abovementioned radiation field. The average differences in organ equivalent dose coefficients between the Chinese and the ICRP adult reference phantoms are within 6% for most organs, but noticeable differences of up to 70% or even higher are found at photon energies below 30 keV under air submersion. The effective dose coefficients obtained with the Chinese adult reference phantoms are greater than those of the ICRP adult reference phantoms above 30 keV and 0.5 MeV for ground contamination and air submersion, respectively; the average differences from the Chinese adult reference phantoms are about 3.6% and 0.4% in the whole energy range with maximum differences of 31.8% and 27.6% at 15 keV for air submersion and ground contamination respectively. These differences are attributed to anatomical discrepancies in overlying tissue mass of an individual organ and the body mass between the Chinese and the ICRP adult reference phantoms. These monoenergetic photon conversion coefficients are subsequently used to evaluate radionuclides with decay data from ICRP publication 107.

Dosimetric impact of applicator displacement during high dose rate (HDR) Cobalt-60 brachytherapy for cervical cancer: A planning study

NASA Astrophysics Data System (ADS)

Yong, J. S.; Ung, N. M.; Jamalludin, Z.; Malik, R. A.; Wong, J. H. D.; Liew, Y. M.; Ng, K. H.

2016-02-01

We investigated the dosimetric impact of applicator displacement on dose specification during high dose rate (HDR) Cobalt-60 (Co-60) brachytherapy for cervical cancer through a planning study. Eighteen randomly selected HDR full insertion plans were restrospectively studied. The tandem and ovoids were virtually shifted translationally and rotationally in the x-, y- and z-axis directions on the treatment planning system. Doses to reference points and volumes of interest in the plans with shifted applicators were compared with the original plans. The impact of dose displacement on 2D (point-based) and 3D (volume-based) treatment planning techniques was also assessed. A ±2 mm translational y-axis applicator shift and ±4° rotational x-axis applicator shift resulted in dosimetric changes of more than 5% to organs at risk (OAR) reference points. Changes to the maximum doses to 2 cc of the organ (D2cc) in 3D planning were statistically significant and higher than the reference points in 2D planning for both the rectum and bladder (p<0.05). Rectal D2cc was observed to be the most sensitive to applicator displacement among all dose metrics. Applicator displacement that is greater than ±2 mm translational y-axis and ±4° rotational x-axis resulted in significant dose changes to the OAR. Thus, steps must be taken to minimize the possibility of applicator displacement during brachytherapy.

Laboratory measurement of apixaban using anti-factor Xa assays in acute ischemic stroke patients with non-valvular atrial fibrillation.

PubMed

Shin, Hyoshim; Cho, Min-Chul; Kim, Rock Bum; Kim, Chang-Hun; Choi, Nack-Cheon; Kim, Soo-Kyung; Koh, Eun-Ha

2018-02-01

Apixaban is effective and safe for preventing stroke, and its usage has increased exponentially in recent years. However, data concerning the therapeutic range of apixaban is limited. This study determined the trough and peak levels of apixaban-specific anti-factor Xa activity (AFXaA) in acute ischemic stroke patients with non-valvular atrial fibrillation (NVAF) in Korea. The study included 85 patients who received apixaban. Blood samples were taken to measure the trough and peak levels of AFXaA using a chromogenic anti-factor assay, as well as prothrombin time (PT) and activated partial thromboplastin time (aPTT). We also reviewed complications such as major bleeding of patients treated with apixaban. In patients given a 5.0-mg apixaban dose, the median trough and peak levels of AFXaA were 104.5 and 202.0 ng/mL. In patients given a 2.5-mg apixaban dose, the median trough and peak AFXaA levels were 76.0 and 151.0 ng/mL. The PT showed a positive correlation with increased AFXaA activity at both levels (Trough R = 0.486, Peak R = 0.592), but the aPTT had no relationship with AFXaA activity at both levels (Trough R = 0.181, Peak R = 0.129). Two cases with intracranial bleeding belonged to the highest AFXaA quartile (Trough, p = 0.176; Peak, p = 0.053). In conclusion, we determined the trough and peak levels of AFXaA in patients with NVAF while being treated with the apixaban in Korea. Our results could be used as a starting point when setting the reference ranges for laboratories using anti-Xa assay. Large-scale studies are needed to establish the reference range for AFXaA in patients with NVAF.

SU-C-202-05: Pilot Study of Online Treatment Evaluation and Adaptive Re-Planning for Laryngeal SBRT

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

Mao, W; Henry Ford Health System, Detroit, MI; Liu, C

Purpose: We have instigated a phase I trial of 5-fraction stereotactic body radiotherapy (SBRT) for advanced-stage laryngeal cancer. We conducted this pilot dosimetric study to confirm the potential utility of online adaptive re-planning to preserve treatment quality. Methods: Ten cases of larynx cancer were evaluated. Baseline and daily SBRT treatment plans were generated per trial protocol. Daily volumetric images were acquired prior to every fraction of treatment. Reference simulation CT images were deformably registered to daily volumetric images using Eclipse. Planning contours were then deformably propagated to daily images. Reference SBRT plans were directly copied to calculate delivered dose distributionsmore » on deformed reference CT images. In-house software platform has been developed to calculate cumulative dose over a course of treatment in four steps: 1) deforming delivered dose grid to reference CT images using deformation information exported from Eclipse; 2) generating tetrahedrons using deformed dose grid as vertices; 3) resampling dose to a high resolution within every tetrahedron; 4) calculating dose-volume histograms. Our inhouse software was benchmarked with a commercial software, Mirada. Results: In all ten cases including 49 fractions of treatments, delivered daily doses were completely evaluated and treatment could be re-planned within 10 minutes. Prescription dose coverage of PTV was less than intended in 53% of fractions of treatment (mean: 94%, range: 84%–98%) while minimum coverage of CTV and GTV was 94% and 97%, respectively. Maximum bystander point dose limits to arytenoids, parotids, and spinal cord remained respected in all cases, although variances in carotid artery doses were observed in a minority of cases. Conclusion: Although GTV and CTV coverage is preserved by in-room 3D image guidance of larynx SBRT, PTV coverage can vary significantly from intended plans. Online adaptive treatment evaluation and re-planning is potentially necessary and our procedure is clinically applicable to fully preserve treatment quality. This project is supported by CPRIT Individual Investigator Research Award RP150386.« less

The impact of the oxygen scavenger on the dose-rate dependence and dose sensitivity of MAGIC type polymer gels

NASA Astrophysics Data System (ADS)

Khan, Muzafar; Heilemann, Gerd; Kuess, Peter; Georg, Dietmar; Berg, Andreas

2018-03-01

Recent developments in radiation therapy aimed at more precise dose delivery along with higher dose gradients (dose painting) and more efficient dose delivery with higher dose rates e.g. flattening filter free (FFF) irradiation. Magnetic-resonance-imaging based polymer gel dosimetry offers 3D information for precise dose delivery techniques. Many of the proposed polymer gels have been reported to exhibit a dose response, measured as relaxation rate ΔR2(D), which is dose rate dependent. A lack of or a reduced dose-rate sensitivity is very important for dosimetric accuracy, especially with regard to the increasing clinical use of FFF irradiation protocols with LINACs at high dose rates. Some commonly used polymer gels are based on Methacrylic-Acid-Gel-Initiated-by-Copper (MAGIC). Here, we report on the dose sensitivity (ΔR2/ΔD) of MAGIC-type gels with different oxygen scavenger concentration for their specific dependence on the applied dose rate in order to improve the dosimetric performance, especially for high dose rates. A preclinical x-ray machine (‘Yxlon’, E  =  200 kV) was used for irradiation to cover a range of dose rates from low \\dot{D} min  =  0.6 Gy min-1 to high \\dot{D} max  =  18 Gy min-1. The dose response was evaluated using R2-imaging of the gel on a human high-field (7T) MR-scanner. The results indicate that all of the investigated dose rates had an impact on the dose response in polymer gel dosimeters, being strongest in the high dose region and less effective for low dose levels. The absolute dose rate dependence \\frac{(Δ R2/Δ D)}{Δ \\dot{D}} of the dose response in MAGIC-type gel is significantly reduced using higher concentrations of oxygen scavenger at the expense of reduced dose sensitivity. For quantitative dose evaluations the relative dose rate dependence of a polymer gel, normalized to its sensitivity is important. Based on this normalized sensitivity the dose rate sensitivity was reduced distinctly using an increased oxygen scavenger concentration with reference to standard MAGIC-type gel formulation at high dose rate levels. The proposed gel composition with high oxygen scavenger concentration exhibits a larger linear active dose response and might be used especially in FFF-radiation applications and preclinical dosimetry at high dose rates. We propose in general to use high dose rates for calibration and evaluation as the change in relative dose sensitivity is reduced at higher dose rates in all of the investigated gel types.

Assessment of background gamma radiation levels using airborne gamma ray spectrometer data over uranium deposits, Cuddapah Basin, India - A comparative study of dose rates estimated by AGRS and PGRS.

PubMed

Srinivas, D; Ramesh Babu, V; Patra, I; Tripathi, Shailesh; Ramayya, M S; Chaturvedi, A K

2017-02-01

The Atomic Minerals Directorate for Exploration and Research (AMD) has conducted high-resolution airborne gamma ray spectrometer (AGRS), magnetometer and time domain electromagnetic (TDEM) surveys for uranium exploration, along the northern margins of Cuddapah Basin. The survey area includes well known uranium deposits such as Lambapur-Peddagattu, Chitrial and Koppunuru. The AGRS data collected for uranium exploration is utilised for estimating the average absorbed rates in air due to radio-elemental (potassium in %, uranium and thorium in ppm) distribution over these known deposit areas. Further, portable gamma ray spectrometer (PGRS) was used to acquire data over two nearby locations one from Lambapur deposit, and the other from known anomalous zone and subsequently average gamma dose rates were estimated. Representative in-situ rock samples were also collected from these two areas and subjected to radio-elemental concentration analysis by gamma ray spectrometer (GRS) in the laboratory and then dose rates were estimated. Analyses of these three sets of results complement one another, thereby providing a comprehensive picture of the radiation environment over these deposits. The average absorbed area wise dose rate level is estimated to be 130 ± 47 nGy h -1 in Lambapur-Peddagattu, 186 ± 77 nGy h -1 in Chitrial and 63 ± 22 nGy h -1 in Koppunuru. The obtained average dose levels are found to be higher than the world average value of 54 nGy h -1 . The gamma absorbed dose rates in nGy h -1 were converted to annual effective dose rates in mSv y -1 as proposed by the United Nations Scientific Committee on the Effect of Atomic Radiation (UNSCEAR). The annual average effective dose rates for the entire surveyed area is 0.12 mSv y -1 , which is much lower than the recommended limit of 1 mSv y -1 by International Commission on Radiation protection (ICRP). It may be ascertained here that the present study establishes a reference data set (baseline) in these areas to assess any changes in gamma radiation levels due to mining and milling activities in future. Copyright © 2016 Elsevier Ltd. All rights reserved.

Individualized adjustments to reference phantom internal organ dosimetry—scaling factors given knowledge of patient internal anatomy

NASA Astrophysics Data System (ADS)

Wayson, Michael B.; Bolch, Wesley E.

2018-04-01

Various computational tools are currently available that facilitate patient organ dosimetry in diagnostic nuclear medicine, yet they are typically restricted to reporting organ doses to ICRP-defined reference phantoms. The present study, while remaining computational phantom based, provides straightforward tools to adjust reference phantom organ dose for both internal photon and electron sources. A wide variety of monoenergetic specific absorbed fractions were computed using radiation transport simulations for tissue spheres of varying size and separation distance. Scaling methods were then constructed for both photon and electron self-dose and cross-dose, with data validation provided from patient-specific voxel phantom simulations, as well as via comparison to the scaling methodology given in MIRD Pamphlet No. 11. Photon and electron self-dose was found to be dependent on both radiation energy and sphere size. Photon cross-dose was found to be mostly independent of sphere size. Electron cross-dose was found to be dependent on sphere size when the spheres were in close proximity, owing to differences in electron range. The validation studies showed that this dataset was more effective than the MIRD 11 method at predicting patient-specific photon doses for at both high and low energies, but gave similar results at photon energies between 100 keV and 1 MeV. The MIRD 11 method for electron self-dose scaling was accurate for lower energies but began to break down at higher energies. The photon cross-dose scaling methodology developed in this study showed gains in accuracy of up to 9% for actual patient studies, and the electron cross-dose scaling methodology showed gains in accuracy up to 9% as well when only the bremsstrahlung component of the cross-dose was scaled. These dose scaling methods are readily available for incorporation into internal dosimetry software for diagnostic phantom-based organ dosimetry.

Individualized adjustments to reference phantom internal organ dosimetry-scaling factors given knowledge of patient internal anatomy.

PubMed

Wayson, Michael B; Bolch, Wesley E

2018-04-13

Various computational tools are currently available that facilitate patient organ dosimetry in diagnostic nuclear medicine, yet they are typically restricted to reporting organ doses to ICRP-defined reference phantoms. The present study, while remaining computational phantom based, provides straightforward tools to adjust reference phantom organ dose for both internal photon and electron sources. A wide variety of monoenergetic specific absorbed fractions were computed using radiation transport simulations for tissue spheres of varying size and separation distance. Scaling methods were then constructed for both photon and electron self-dose and cross-dose, with data validation provided from patient-specific voxel phantom simulations, as well as via comparison to the scaling methodology given in MIRD Pamphlet No. 11. Photon and electron self-dose was found to be dependent on both radiation energy and sphere size. Photon cross-dose was found to be mostly independent of sphere size. Electron cross-dose was found to be dependent on sphere size when the spheres were in close proximity, owing to differences in electron range. The validation studies showed that this dataset was more effective than the MIRD 11 method at predicting patient-specific photon doses for at both high and low energies, but gave similar results at photon energies between 100 keV and 1 MeV. The MIRD 11 method for electron self-dose scaling was accurate for lower energies but began to break down at higher energies. The photon cross-dose scaling methodology developed in this study showed gains in accuracy of up to 9% for actual patient studies, and the electron cross-dose scaling methodology showed gains in accuracy up to 9% as well when only the bremsstrahlung component of the cross-dose was scaled. These dose scaling methods are readily available for incorporation into internal dosimetry software for diagnostic phantom-based organ dosimetry.

Comparison of current recommended regimens of atropinization in organophosphate poisoning.

PubMed

Connors, Nicholas J; Harnett, Zachary H; Hoffman, Robert S

2014-06-01

Atropine is the mainstay of therapy in organophosphate (OP) toxicity, though research and consensus on dosing is lacking. In 2004, as reported by Eddleston et al. (J Toxicol Clin Toxicol 42(6):865-75, 2004), they noted variation in recommended regimens. We assessed revisions of original references, additional citations, and electronic sources to determine the current variability in atropine dosing recommendations. Updated editions of references from Eddleston et al.'s work, texts of Internal and Emergency Medicine, and electronic resources were reviewed for atropine dosing recommendations. For comparison, recommendations were assessed using the same mean dose (23.4 mg) and the highest dose (75 mg) of atropine as used in the original paper. Recommendations were also compared with the dosing regimen from the World Health Organization (WHO). Thirteen of the original recommendations were updated and 15 additional references were added giving a convenience sample of 28. Sufficient information to calculate time to targeted dose was provided by 24 of these samples. Compared to 2004, current recommendations have greatly increased the speed of atropinization with 13/24 able to reach the mean and high atropine dose within 30 min compared to 1/36 in 2004. In 2004, there were 13 regimens where the maximum time to reach 75 mg was over 18 h, whereas now, there are 2. While only one recommendation called for doubling the dose for faster escalation in 2004, 15 of the 24 current works include dose doubling. In 2004, Eddleston et al. called for an evidence-based guideline for the treatment of OP poisoning that could be disseminated worldwide. Many current recommendations can adequately treat patients within 1 h. While the WHO recommendations remain slow to treat patients with OP poisoning, other authorities are close to a consensus on rapid atropinization.

Adaptive control of bivalirudin in the cardiac intensive care unit.

PubMed

Zhao, Qi; Edrich, Thomas; Paschalidis, Ioannis Ch

2015-02-01

Bivalirudin is a direct thrombin inhibitor used in the cardiac intensive care unit when heparin is contraindicated due to heparin-induced thrombocytopenia. Since it is not a commonly used drug, clinical experience with its dosing is sparse. In earlier work [1], we developed a dynamic system model that accurately predicts the effect of bivalirudin given dosage over time and patient physiological characteristics. This paper develops adaptive dosage controllers that regulate its effect to desired levels. To that end, and in the case that bivalirudin model parameters are available, we develop a Model Reference Control law. In the case that model parameters are unknown, an indirect Model Reference Adaptive Control scheme is applied to estimate model parameters first and then adapt the controller. Alternatively, direct Model Reference Adaptive Control is applied to adapt the controller directly without estimating model parameters first. Our algorithms are validated using actual patient data from a large hospital in the Boston area.

Thermoluminescent dosimeters (TLD) quality assurance network in the Czech Republic.

PubMed

Kroutilķková, Daniela; Novotný, Josef; Judas, Libor

2003-02-01

The Czech thermoluminescent dosimeters (TLD) quality assurance network was established in 1997. Its aim is to pursue a regular independent quality audit in Czech radiotherapy centres and to support state supervision. The audit is realised via mailed TL dosimetry. The TLD system consists of encapsulated LiF:Mg,Ti powder (type MT-N) read with Harshaw manual reader model 4000. Basic mode of the TLD audit covers measurements under reference conditions, specifically beam calibration checks for all clinically used photon and electron beams. Advanced mode consists of measurements under both reference and non-reference conditions using a solid multipurpose phantom ('Leuven phantom') for photon beams. The radiotherapy centres are instructed to deliver to the TLD on central beam axis absorbed dose of 2 Gy calculated with their treatment planning system for a particular treatment set-up. The TLD measured doses are compared with the calculated ones. Deviations of +/-3% are considered acceptable for both basic and advanced mode of the audit. There are 34 radiotherapy centres in the Czech Republic. They undergo the basic mode of the TLD audit regularly every 2 years. If a centre shows a deviation outside the acceptance level, it is audited more often. Presently, most of the checked beams comply with the acceptance level. The advanced TLD audit has been implemented as a pilot study for the present. The results were mostly within the acceptance limit for the measurements on-axis, whereas for off-axis points they fell beyond the limit more frequently, especially for set-ups with inhomogeneities, oblique incidence and wedges. The results prove the importance of the national TLD quality assurance network. It has contributed to the improvement of clinical dosimetry in the Czech Republic. In addition, it helps the regulatory authority to monitor effectively and regularly radiotherapy centres.

Review of the Reference Dose and Reference Concentration Processes Document

EPA Pesticide Factsheets

Summarizes the review and deliberations of the Risk Assessment Forum’s RfD/RfC Technical Panel and its recommendations for improvements in oral referencedose/inhalation reference concentration (RfD/RfC) process.

Screening-Level Risk Assessment for Styrene-Acrylonitrile (SAN) Trimer Detected in Soil and Groundwater

PubMed Central

Kirman, C. R.; Gargas, M. L.; Collins, J. J.; Rowlands, J. C.

2012-01-01

A screening-level risk assessment was conducted for styrene-acrylonitrile (SAN) Trimer detected at the Reich Farm Superfund site in Toms River, NJ. Consistent with a screening-level approach, on-site and off-site exposure scenarios were evaluated using assumptions that are expected to overestimate actual exposures and hazards at the site. Environmental sampling data collected for soil and groundwater were used to estimate exposure point concentrations. Several exposure scenarios were evaluated to assess potential on-site and off-site exposures, using parameter values for exposures to soil (oral, inhalation of particulates, and dermal contact) and groundwater (oral, dermal contact) to reflect central tendency exposure (CTE) and reasonable maximum exposure (RME) conditions. Three reference dose (RfD) values were derived for SAN Trimer for short-term, subchronic, and chronic exposures, based upon its effects on the liver in exposed rats. Benchmark (BMD) methods were used to assess the relationship between exposure and response, and to characterize appropriate points of departure (POD) for each RfD. An uncertainty factor of 300 was applied to each POD to yield RfD values of 0.1, 0.04, and 0.03 mg/kg-d for short-term, subchronic, and chronic exposures, respectively. Because a chronic cancer bioassay for SAN Trimer in rats (NTP 2011a) does not provide evidence of carcinogenicity, a cancer risk assessment is not appropriate for this chemical. Potential health hazards to human health were assessed using a hazard index (HI) approach, which considers the ratio of exposure dose (i.e., average daily dose, mg/kg-d) to toxicity dose (RfD, mg/kg-d) for each scenario. All CTE and RME HI values are well below 1 (where the average daily dose is equivalent to the RfD), indicating that there is no concern for potential noncancer effects in exposed populations even under the conservative assumptions of this screening-level assessment. PMID:23030654

Effectiveness of thyroid gland shielding in dental CBCT using a paediatric anthropomorphic phantom

PubMed Central

Davies, J; Horner, K; Theodorakou, C

2015-01-01

Objectives: The purpose of the study is to evaluate the effectiveness of thyroid shielding in dental CBCT examinations using a paediatric anthropomorphic phantom. Methods: An ATOM® 706-C anthropomorphic phantom (Computerized Imaging Reference Systems Inc., Norfolk, VA) representing a 10-year-old child was loaded with six thermoluminescent dosemeters positioned at the level of the thyroid gland. Absorbed doses to the thyroid were measured for five commercially available thyroid shields using a large field of view (FOV). Results: A statistically significant thyroid gland dose reduction was found using thyroid shielding for paediatric CBCT examinations for a large FOV. In addition, a statistically significant difference in thyroid gland doses was found depending on the position of the thyroid gland. There was little difference in the effectiveness of thyroid shielding when using a lead vs a lead-equivalent thyroid shield. Similar dose reduction was found using 0.25- and 0.50-mm lead-equivalent thyroid shields. Conclusions: Thyroid shields are to be recommended when undertaking large FOV CBCT examinations on young patients. PMID:25411710

A formalism for reference dosimetry in photon beams in the presence of a magnetic field

NASA Astrophysics Data System (ADS)

van Asselen, B.; Woodings, S. J.; Hackett, S. L.; van Soest, T. L.; Kok, J. G. M.; Raaymakers, B. W.; Wolthaus, J. W. H.

2018-06-01

A generic formalism is proposed for reference dosimetry in the presence of a magnetic field. Besides the regular correction factors from the conventional reference dosimetry formalisms, two factors are used to take into account magnetic field effects: (1) a dose conversion factor to correct for the change in local dose distribution and (2) a correction of the reading of the dosimeter used for the reference dosimetry measurements. The formalism was applied to the Elekta MRI-Linac, for which the 1.5 T magnetic field is orthogonal to the 7 MV photon beam. For this setup at reference conditions it was shown that the dose decreases with increasing magnetic field strength. The reduction in local dose for a 1.5 T transverse field, compared to no field is 0.51%  ±  0.03% at the reference point of 10 cm depth. The effect of the magnetic field on the reading of the dosimeter was measured for two waterproof ionization chambers types (PTW 30013 and IBA FC65-G) before and after multiple ramp-up and ramp-downs of the magnetic field. The chambers were aligned perpendicular and parallel to the magnetic field. The corrections of the readings of the perpendicularly aligned chambers were 0.967  ±  0.002 and 0.957  ±  0.002 for respectively the PTW and IBA ionization chambers. In the parallel alignment the corrections were small; 0.997  ±  0.001 and 1.002  ±  0.003 for the PTW and IBA chamber respectively. The change in reading due to the magnetic field can be measured by individual departments. The proposed formalism can be used to determine the correction factors needed to establish the absorbed dose in a magnetic field. It requires Monte Carlo simulations of the local dose and measurements of the response of the dosimeter. The formalism was successfully implemented for the MRI-Linac and is applicable for other field strengths and geometries.

A formalism for reference dosimetry in photon beams in the presence of a magnetic field.

PubMed

van Asselen, B; Woodings, S J; Hackett, S L; van Soest, T L; Kok, J G M; Raaymakers, B W; Wolthaus, J W H

2018-06-11

A generic formalism is proposed for reference dosimetry in the presence of a magnetic field. Besides the regular correction factors from the conventional reference dosimetry formalisms, two factors are used to take into account magnetic field effects: (1) a dose conversion factor to correct for the change in local dose distribution and (2) a correction of the reading of the dosimeter used for the reference dosimetry measurements. The formalism was applied to the Elekta MRI-Linac, for which the 1.5 T magnetic field is orthogonal to the 7 MV photon beam. For this setup at reference conditions it was shown that the dose decreases with increasing magnetic field strength. The reduction in local dose for a 1.5 T transverse field, compared to no field is 0.51%  ±  0.03% at the reference point of 10 cm depth. The effect of the magnetic field on the reading of the dosimeter was measured for two waterproof ionization chambers types (PTW 30013 and IBA FC65-G) before and after multiple ramp-up and ramp-downs of the magnetic field. The chambers were aligned perpendicular and parallel to the magnetic field. The corrections of the readings of the perpendicularly aligned chambers were 0.967  ±  0.002 and 0.957  ±  0.002 for respectively the PTW and IBA ionization chambers. In the parallel alignment the corrections were small; 0.997  ±  0.001 and 1.002  ±  0.003 for the PTW and IBA chamber respectively. The change in reading due to the magnetic field can be measured by individual departments. The proposed formalism can be used to determine the correction factors needed to establish the absorbed dose in a magnetic field. It requires Monte Carlo simulations of the local dose and measurements of the response of the dosimeter. The formalism was successfully implemented for the MRI-Linac and is applicable for other field strengths and geometries.

Calibration of helical tomotherapy machine using EPR/alanine dosimetry.

PubMed

Perichon, Nicolas; Garcia, Tristan; François, Pascal; Lourenço, Valérie; Lesven, Caroline; Bordy, Jean-Marc

2011-03-01

Current codes of practice for clinical reference dosimetry of high-energy photon beams in conventional radiotherapy recommend using a 10 x 10 cm2 square field, with the detector at a reference depth of 10 cm in water and 100 cm source to surface distance (SSD) (AAPM TG-51) or 100 cm source-to-axis distance (SAD) (IAEA TRS-398). However, the maximum field size of a helical tomotherapy (HT) machine is 40 x 5 cm2 defined at 85 cm SAD. These nonstandard conditions prevent a direct implementation of these protocols. The purpose of this study is twofold: To check the absorbed dose in water and dose rate calibration of a tomotherapy unit as well as the accuracy of the tomotherapy treatment planning system (TPS) calculations for a specific test case. Both topics are based on the use of electron paramagnetic resonance (EPR) using alanine as transfer dosimeter between the Laboratoire National Henri Becquerel (LNHB) 60Co-gamma-ray reference beam and the Institut Curie's HT beam. Irradiations performed in the LNHB reference 60Co-gamma-ray beam allowed setting up the calibration method, which was then implemented and tested at the LNHB 6 MV linac x-ray beam, resulting in a deviation of 1.6% (at a 1% standard uncertainty) relative to the reference value determined with the standard IAEA TRS-398 protocol. HT beam dose rate estimation shows a difference of 2% with the value stated by the manufacturer at a 2% standard uncertainty. A 4% deviation between measured dose and the calculation from the tomotherapy TPS was found. The latter was originated by an inadequate representation of the phantom CT-scan values and, consequently, mass densities within the phantom. This difference has been explained by the mass density values given by the CT-scan and used by the TPS which were not the true ones. Once corrected using Monte Carlo N-Particle simulations to validate the accuracy of this process, the difference between corrected TPS calculations and alanine measured dose values was then found to be around 2% (with 2% standard uncertainty on TPS doses and 1.5% standard uncertainty on EPR measurements). Beam dose rate estimation results were found to be in good agreement with the reference value given by the manufacturer at 2% standard uncertainty. Moreover, the dose determination method was set up with a deviation around 2% (at a 2% standard uncertainty).

Low dose evaluation of the antiandrogen flutamide following a Mode of Action approach

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

Sarrabay, A.; UniverSud, INSERM, UMR-996 “Inflammation, Chemokines and Immunopathology”, Châtenay-Malabry; Bayer SAS, 16, rue Jean Marie Leclair, 69009 Lyon

ABSTRACT: The dose–response characterization of endocrine mediated toxicity is an on-going debate which is controversial when exploring the nature of the dose–response curve and the effect at the low-end of the curve. To contribute to this debate we have assessed the effects of a wide range of dose levels of the antiandrogen flutamide (FLU) on 7-week male Wistar rats. FLU was administered by oral gavage at doses of 0, 0.001, 0.01, 0.1, 1 and 10 mg/kg/day for 28 days. To evaluate the reproducibility, the study was performed 3 times. The molecular initiating event (MIE; AR antagonism), the key events (LHmore » increase, Leydig cell proliferation and hyperplasia increases) and associated events involved in the mode of action (MOA) of FLU induced testicular toxicity were characterized to address the dose response concordance. Results showed no effects at low doses (< 0.1 mg/kg/day) for the different key events studied. The histopathological changes (Leydig cell hyperplasia) observed at 1 and 10 mg/kg/day were associated with an increase in steroidogenesis gene expression in the testis from 1 mg/kg/day, as well as an increase in testosterone blood level at 10 mg/kg/day. Each key event dose–response was in good concordance with the MOA of FLU on the testis. From the available results, only monotonic dose–response curves were observed for the MIE, the key events, associated events and in effects observed in other sex related tissues. All the results, so far, show that the reference endocrine disruptor FLU induces threshold effects in a standard 28-day toxicity study on adult male rats. - Highlights: • Dose–response characterization of endocrine mediated toxicity is an on-going debate. • A wide range of dose levels of flutamide was evaluated on young adult male rats. • Flutamide induces threshold effects using on standard and molecular tools.« less

Quality of pediatric abdominal CT scans performed at a dedicated children's hospital and its referring institutions: a multifactorial evaluation.

PubMed

Snow, Aisling; Milliren, Carly E; Graham, Dionne A; Callahan, Michael J; MacDougall, Robert D; Robertson, Richard L; Taylor, George A

2017-04-01

Pediatric patients requiring transfer to a dedicated children's hospital from an outside institution may undergo CT imaging as part of their evaluation. Whether this imaging is performed prior to or after transfer has been shown to impact the radiation dose imparted to the patient. Other quality variables could also be affected by the pediatric experience and expertise of the scanning institution. To identify differences in quality between abdominal CT scans and reports performed at a dedicated children's hospital, and those performed at referring institutions. Fifty consecutive pediatric abdominal CT scans performed at outside institutions were matched (for age, gender and indication) with 50 CT scans performed at a dedicated freestanding children's hospital. We analyzed the scans for technical parameters, report findings, correlation with final clinical diagnosis, and clinical utility. Technical evaluation included use of intravenous and oral contrast agents, anatomical coverage, number of scan phases and size-specific dose estimate (SSDE) for each scan. Outside institution scans were re-reported when the child was admitted to the children's hospital; they were also re-interpreted for this study by children's hospital radiologists who were provided with only the referral information given in the outside institution's report. Anonymized original outside institutional reports and children's hospital admission re-reports were analyzed by two emergency medicine physicians for ease of understanding, degree to which the clinical question was answered, and level of confidence in the report. Mean SSDE was lower (8.68) for children's hospital scans, as compared to outside institution scans (13.29, P = 0.03). Concordance with final clinical diagnosis was significantly lower for original outside institution reports (38/48, 79%) than for both the admission and study children's hospital reports (48/50, 96%; P = 0.005). Children's hospital admission reports were rated higher than outside institution reports for completeness, ease of understanding, answering of clinical question, and level of confidence of the report (P < 0.001). Pediatric abdominal CT scans performed and interpreted at a dedicated children's hospital are associated with higher technical quality, lower radiation dose and a more clinically useful report than those performed at referring institutions.

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

Harrison, F.L.; Rice, D.W. Jr.; Moore, D.H.

Traditional bioassays are unsuitable for assessing sublethal effects of low levels of radioactivity because mortality and phenotypic responses are not anticipated. We compared the usefulness of chromosomal aberration (CA) and sister chromatid exchange (SCE) induction as measures of low-level radiation effects in a sediment-dwelling marine worm, Neanthes arenaceodentata. Newly hatched larvae were exposed to two radiation exposure regimes. Groups of 100 larvae were exposed to either x rays delivered at high dose rates (0.7 Gy min/sup -1/) or to /sup 60/Co gamma rays delivered at low dose rates (4.8 X 10/sup -5/ to 1.2 X 10/sup -1/ Gy h/sup -1/).more » After irradiation, the larvae were exposed to 3 X 10/sup -5/M bromodeoxyuridine (BrdUrd) for 28 h (x-ray-irradiated larvae) or for 54 h (/sup 60/Co-irradiated larvae). Slides of larval cells were prepared for observation of CAs and SCEs. Frequencies of CAs were determined in first division cells; frequencies of SCEs were determined in second division cells. Results from x-ray irradiation indicated that dose-related increases occur in chromosome and chromatid deletions, but an x-ray dose greater than or equal to 2 Gy was required to observe a significant increase. Worm larvae receiving /sup 60/Co irradiation showed elevated SCE frequencies; a significant increase in SCE frequency was observed at 0.6 Gy. 49 references, 2 figures.« less

Impact of interpatient variability on organ dose estimates according to MIRD schema: Uncertainty and variance-based sensitivity analysis.

PubMed

Zvereva, Alexandra; Kamp, Florian; Schlattl, Helmut; Zankl, Maria; Parodi, Katia

2018-05-17

Variance-based sensitivity analysis (SA) is described and applied to the radiation dosimetry model proposed by the Committee on Medical Internal Radiation Dose (MIRD) for the organ-level absorbed dose calculations in nuclear medicine. The uncertainties in the dose coefficients thus calculated are also evaluated. A Monte Carlo approach was used to compute first-order and total-effect SA indices, which rank the input factors according to their influence on the uncertainty in the output organ doses. These methods were applied to the radiopharmaceutical (S)-4-(3- 18 F-fluoropropyl)-L-glutamic acid ( 18 F-FSPG) as an example. Since 18 F-FSPG has 11 notable source regions, a 22-dimensional model was considered here, where 11 input factors are the time-integrated activity coefficients (TIACs) in the source regions and 11 input factors correspond to the sets of the specific absorbed fractions (SAFs) employed in the dose calculation. The SA was restricted to the foregoing 22 input factors. The distributions of the input factors were built based on TIACs of five individuals to whom the radiopharmaceutical 18 F-FSPG was administered and six anatomical models, representing two reference, two overweight, and two slim individuals. The self-absorption SAFs were mass-scaled to correspond to the reference organ masses. The estimated relative uncertainties were in the range 10%-30%, with a minimum and a maximum for absorbed dose coefficients for urinary bladder wall and heart wall, respectively. The applied global variance-based SA enabled us to identify the input factors that have the highest influence on the uncertainty in the organ doses. With the applied mass-scaling of the self-absorption SAFs, these factors included the TIACs for absorbed dose coefficients in the source regions and the SAFs from blood as source region for absorbed dose coefficients in highly vascularized target regions. For some combinations of proximal target and source regions, the corresponding cross-fire SAFs were found to have an impact. Global variance-based SA has been for the first time applied to the MIRD schema for internal dose calculation. Our findings suggest that uncertainties in computed organ doses can be substantially reduced by performing an accurate determination of TIACs in the source regions, accompanied by the estimation of individual source region masses along with the usage of an appropriate blood distribution in a patient's body and, in a few cases, the cross-fire SAFs from proximal source regions. © 2018 American Association of Physicists in Medicine.

Management of testosterone therapy in adolescents and young men with hypogonadism: are we following adult clinical practice guidelines?

PubMed

Nahata, Leena; Yu, Richard N; Bhasin, Shalender; Cohen, Laurie E

2015-05-01

Male hypogonadism is a common disorder that is associated with low bone density, poor muscle mass, anemia, and sexual dysfunction. The Endocrine Society recently published a Clinical Practice Guideline for testosterone therapy in androgen-deficient men. Because treatment is frequently initiated in adolescence, the goal of this quality improvement initiative was to assess whether pediatric endocrinologists at a large tertiary care center follow these guidelines and to identify opportunities for improvement. We performed a retrospective chart review at Boston Children's Hospital. Inclusion criteria were as follows: current age ≥16 years, diagnosis of hypogonadism, and testosterone replacement therapy. Data were collected about current age, age at treatment initiation, diagnoses, pre- and on-treatment testosterone levels, route of testosterone administration and dose, bone density, hematocrit levels, and adherence with therapy. Fifty-nine patients were included. Fourteen (24%) were prescribed lower testosterone doses than those recommended in the Clinical Practice Guideline. Seven (12%) had no pre-treatment testosterone levels, and 10 (17%) had no on-treatment levels. In 49 patients with on-treatment testosterone levels, 36 had at least one value that was lower than the adult reference range. Ten (28%) of the 36 men with low testosterone levels had no dose adjustments. Thirty-seven (63%) of the 59 patients had no dual-energy X-ray absorptiometry scans, and 18 (31%) did not have hematocrit levels. Pediatric endocrinologists in this review did not consistently follow the Clinical Practice Guideline for testosterone therapy in hypogonadal adult males. Strategies that improve adherence to guidelines could help maximize the benefits of therapy and minimize treatment-associated risks.

Accuracy of a dose-area product compared to an absorbed dose to water at a point in a 2 cm diameter field

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

Dufreneix, S.; Ostrowsky, A.; Rapp, B.

Purpose: Graphite calorimeters with a core diameter larger than the beam can be used to establish dosimetric references in small fields. The dose-area product (DAP) measured can theoretically be linked to an absorbed dose at a point by the determination of a profile correction. This study aims at comparing the DAP-based protocol to the usual absorbed dose at a point protocol in a 2 cm diameter field for which both references exist. Methods: Two calorimeters were used, respectively, with a sensitive volume of 0.6 cm (for the absorbed dose at a point measurement) and 3 cm diameter (for the DAPmore » measurement). Profile correction was calculated from a 2D dose mapping using three detectors: a PinPoint chamber, a synthetic diamond, and EBT3 films. A specific protocol to read EBT3 films was implemented and the dose-rate and energy dependences were studied to assure a precise measurement, especially in the penumbra and out-of-field regions. Results: EBT3 films were found independent on dose rates over the range studied but showed a strong under-response (18%) at low energies. Depending on the dosimeter used for calculating the profile correction, a deviation of 0.8% (PinPoint chamber), 0.9% (diamond), or 1.9% (EBT3 films) was observed between the calibration coefficient derived from DAP measurements and the one directly established in terms of absorbed dose to water at a point. Conclusions: The DAP method can currently be linked to the classical dosimetric reference system based in an absorbed dose at a point only with a confidence interval of 95% (k = 2). None of the detectors studied can be used to determine an absorbed dose to water at a point from a DAP measurement with an uncertainty smaller than 1.2%.« less

Ultra-low power high temperature and radiation hard complementary metal-oxide-semiconductor (CMOS) silicon-on-insulator (SOI) voltage reference.

PubMed

Boufouss, El Hafed; Francis, Laurent A; Kilchytska, Valeriya; Gérard, Pierre; Simon, Pascal; Flandre, Denis

2013-12-13

This paper presents an ultra-low power CMOS voltage reference circuit which is robust under biomedical extreme conditions, such as high temperature and high total ionized dose (TID) radiation. To achieve such performances, the voltage reference is designed in a suitable 130 nm Silicon-on-Insulator (SOI) industrial technology and is optimized to work in the subthreshold regime of the transistors. The design simulations have been performed over the temperature range of -40-200 °C and for different process corners. Robustness to radiation was simulated using custom model parameters including TID effects, such as mobilities and threshold voltages degradation. The proposed circuit has been tested up to high total radiation dose, i.e., 1 Mrad (Si) performed at three different temperatures (room temperature, 100 °C and 200 °C). The maximum drift of the reference voltage V(REF) depends on the considered temperature and on radiation dose; however, it remains lower than 10% of the mean value of 1.5 V. The typical power dissipation at 2.5 V supply voltage is about 20 μW at room temperature and only 75 μW at a high temperature of 200 °C. To understand the effects caused by the combination of high total ionizing dose and temperature on such voltage reference, the threshold voltages of the used SOI MOSFETs were extracted under different conditions. The evolution of V(REF) and power consumption with temperature and radiation dose can then be explained in terms of the different balance between fixed oxide charge and interface states build-up. The total occupied area including pad-ring is less than 0.09 mm2.

Meta-analysis of the Association Between the Level of Cannabis Use and Risk of Psychosis

PubMed Central

Marconi, Arianna; Di Forti, Marta; Lewis, Cathryn M.; Murray, Robin M.; Vassos, Evangelos

2016-01-01

Cannabis use has been reported to induce long-lasting psychotic disorders and a dose-response relationship has been observed. We performed a systematic review of studies that investigate the association between the degree of cannabis consumption and psychosis and a meta-analysis to quantify the magnitude of effect. Published studies were identified through search of electronic databases, supplemented by manual searches of bibliographies. Studies were considered if they provided data on cannabis consumption prior to the onset of psychosis using a dose criterion (frequency/amount used) and reported psychosis-related outcomes. We performed random effects meta-analysis of individual data points generated with a simulation method from the summary data of the original studies. From 571 references, 18 studies fulfilled inclusion criteria for the systematic review and 10 were inserted in the meta-analysis, enrolling a total of 66 816 individuals. Higher levels of cannabis use were associated with increased risk for psychosis in all the included studies. A logistic regression model gave an OR of 3.90 (95% CI 2.84 to 5.34) for the risk of schizophrenia and other psychosis-related outcomes among the heaviest cannabis users compared to the nonusers. Current evidence shows that high levels of cannabis use increase the risk of psychotic outcomes and confirms a dose-response relationship between the level of use and the risk for psychosis. Although a causal link cannot be unequivocally established, there is sufficient evidence to justify harm reduction prevention programs. PMID:26884547

Environmental risks of radioactive discharges from a low-level radioactive waste disposal site at Dessel, Belgium.

PubMed

Batlle, J Vives I; Sweeck, L; Wannijn, J; Vandenhove, H

2016-10-01

The potential radiological impact of releases from a low-level radioactive waste (Category A waste) repository in Dessel, Belgium on the local fauna and flora was assessed under a reference scenario for gradual leaching. The potential impact situations for terrestrial and aquatic fauna and flora considered in this study were soil contamination due to irrigation with contaminated groundwater from a well at 70 m from the repository, contamination of the local wetlands receiving the highest radionuclide flux after migration through the aquifer and contamination of the local river receiving the highest radionuclide flux after migration through the aquifer. In addition, an exploratory study was carried out for biota residing in the groundwater. All impact assessments were performed using the Environmental Risk from Ionising Contaminants: Assessment and Management (ERICA) tool. For all scenarios considered, absorbed dose rates to biota were found to be well below the ERICA 10 μGy h -1 screening value. The highest dose rates were observed for the scenario where soil was irrigated with groundwater from the vicinity of the repository. For biota residing in the groundwater well, a few dose rates were slightly above the screening level but significantly below the dose rates at which the smallest effects are observed for those relevant species or groups of species. Given the conservative nature of the assessment, it can be concluded that manmade radionuclides deposited into the environment by the near surface disposal of category A waste at Dessel do not have a significant radiological impact to wildlife. Copyright © 2016 Elsevier Ltd. All rights reserved.

Ultralow-dose CT of the craniofacial bone for navigated surgery using adaptive statistical iterative reconstruction and model-based iterative reconstruction: 2D and 3D image quality.

PubMed

Widmann, Gerlig; Schullian, Peter; Gassner, Eva-Maria; Hoermann, Romed; Bale, Reto; Puelacher, Wolfgang

2015-03-01

OBJECTIVE. The purpose of this article is to evaluate 2D and 3D image quality of high-resolution ultralow-dose CT images of the craniofacial bone for navigated surgery using adaptive statistical iterative reconstruction (ASIR) and model-based iterative reconstruction (MBIR) in comparison with standard filtered backprojection (FBP). MATERIALS AND METHODS. A formalin-fixed human cadaver head was scanned using a clinical reference protocol at a CT dose index volume of 30.48 mGy and a series of five ultralow-dose protocols at 3.48, 2.19, 0.82, 0.44, and 0.22 mGy using FBP and ASIR at 50% (ASIR-50), ASIR at 100% (ASIR-100), and MBIR. Blinded 2D axial and 3D volume-rendered images were compared with each other by three readers using top-down scoring. Scores were analyzed per protocol or dose and reconstruction. All images were compared with the FBP reference at 30.48 mGy. A nonparametric Mann-Whitney U test was used. Statistical significance was set at p < 0.05. RESULTS. For 2D images, the FBP reference at 30.48 mGy did not statistically significantly differ from ASIR-100 at 3.48 mGy, ASIR-100 at 2.19 mGy, and MBIR at 0.82 mGy. MBIR at 2.19 and 3.48 mGy scored statistically significantly better than the FBP reference (p = 0.032 and 0.001, respectively). For 3D images, the FBP reference at 30.48 mGy did not statistically significantly differ from all reconstructions at 3.48 mGy; FBP and ASIR-100 at 2.19 mGy; FBP, ASIR-100, and MBIR at 0.82 mGy; MBIR at 0.44 mGy; and MBIR at 0.22 mGy. CONCLUSION. MBIR (2D and 3D) and ASIR-100 (2D) may significantly improve subjective image quality of ultralow-dose images and may allow more than 90% dose reductions.

HDRK-Woman: whole-body voxel model based on high-resolution color slice images of Korean adult female cadaver

NASA Astrophysics Data System (ADS)

Yeom, Yeon Soo; Jeong, Jong Hwi; Kim, Chan Hyeong; Han, Min Cheol; Ham, Bo Kyoung; Cho, Kun Woo; Hwang, Sung Bae

2014-07-01

In a previous study, we constructed a male reference Korean phantom; HDRK-Man (High-Definition Reference Korean-Man), to represent Korean adult males for radiation protection purposes. In the present study, a female phantom; HDRK-Woman (High-Definition Reference Korean-Woman), was constructed to represent Korean adult females. High-resolution color photographic images obtained by serial sectioning of a 26 year-old Korean adult female cadaver were utilized. The body height and weight, the skeletal mass, and the dimensions of the individual organs and tissues were adjusted to the reference Korean data. The phantom was then compared with the International Commission on Radiological Protection (ICRP) female reference phantom in terms of calculated organ doses and organ-depth distributions. Additionally, the effective doses were calculated using both the HDRK-Man and HDRK-Woman phantoms, and the values were compared with those of the ICRP reference phantoms.

HDRK-Woman: whole-body voxel model based on high-resolution color slice images of Korean adult female cadaver.

PubMed

Yeom, Yeon Soo; Jeong, Jong Hwi; Kim, Chan Hyeong; Han, Min Cheol; Ham, Bo Kyoung; Cho, Kun Woo; Hwang, Sung Bae

2014-07-21

In a previous study, we constructed a male reference Korean phantom; HDRK-Man (High-Definition Reference Korean-Man), to represent Korean adult males for radiation protection purposes. In the present study, a female phantom; HDRK-Woman (High-Definition Reference Korean-Woman), was constructed to represent Korean adult females. High-resolution color photographic images obtained by serial sectioning of a 26 year-old Korean adult female cadaver were utilized. The body height and weight, the skeletal mass, and the dimensions of the individual organs and tissues were adjusted to the reference Korean data. The phantom was then compared with the International Commission on Radiological Protection (ICRP) female reference phantom in terms of calculated organ doses and organ-depth distributions. Additionally, the effective doses were calculated using both the HDRK-Man and HDRK-Woman phantoms, and the values were compared with those of the ICRP reference phantoms.

SU-C-207-02: A Method to Estimate the Average Planar Dose From a C-Arm CBCT Acquisition

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

Supanich, MP

2015-06-15

Purpose: The planar average dose in a C-arm Cone Beam CT (CBCT) acquisition had been estimated in the past by averaging the four peripheral dose measurements in a CTDI phantom and then using the standard 2/3rds peripheral and 1/3 central CTDIw method (hereafter referred to as Dw). The accuracy of this assumption has not been investigated and the purpose of this work is to test the presumed relationship. Methods: Dose measurements were made in the central plane of two consecutively placed 16cm CTDI phantoms using a 0.6cc ionization chamber at each of the 4 peripheral dose bores and in themore » central dose bore for a C-arm CBCT protocol. The same setup was scanned with a circular cut-out of radiosensitive gafchromic film positioned between the two phantoms to capture the planar dose distribution. Calibration curves for color pixel value after scanning were generated from film strips irradiated at different known dose levels. The planar average dose for red and green pixel values was calculated by summing the dose values in the irradiated circular film cut out. Dw was calculated using the ionization chamber measurements and film dose values at the location of each of the dose bores. Results: The planar average dose using both the red and green pixel color calibration curves were within 10% agreement of the planar average dose estimated using the Dw method of film dose values at the bore locations. Additionally, an average of the planar average doses calculated using the red and green calibration curves differed from the ionization chamber Dw estimate by only 5%. Conclusion: The method of calculating the planar average dose at the central plane of a C-arm CBCT non-360 rotation by calculating Dw from peripheral and central dose bore measurements is a reasonable approach to estimating the planar average dose. Research Grant, Siemens AG.« less

EFFECTS OF REACTOR RADIATION ON THE ELECTRICAL PROPERTIES OF ELECTRONIC COMPONENTS. PART II. VACUUM TUBES, TRANSISTORS AND TRANSFORMERS

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

Miglicco, P.S.; Spears, A.B.; Howell, D.B.

1957-11-22

Several types of vacuum tubes, transistors and transformers were irradiated with the Convair-Fort Worth Ground Test Reactor. The components were subjected to five different fluxes ranging from 10/sup 6/ to 10/sup 10/n/sub F// cm/sup 2/-sec and 10/sup 8/ to 10/sup 12/ gamma /cm/sup 2/-sec. The total integrated flux received was 10/sup 14/n/sub F//cm/sup 2/ and 10/sup 16/ gamma / cm/sup 2/. An attempt was made to separate radiation damage as a function of dose rate from radiation damage as a function of dose. The components were irradiated first at several low dose rates so that dose rate effects could bemore » studied while the accumulated dose was small, and then at a high dose rate to obtain the desired dose. However, because of the long time required to complete a data gathering cycle, the accumulated dose hindered the separation of dose rate and dose effects. Thus, in the report, the damage to the components is reported as a function of integrated flux. For reference, the integrated flux accumulated at each power level is given. The transformers exhibited the greatest resistance to irradiation. Every important parameter of the transistors deteriorated in the radiation field. Postirradiation tests at room temperature showed no significant recovery in the transistor's characteristics. The plate current of 65% of the tubes tested increased during irradiation. This effect, based on postirradiation tests, is considered permanent. (auth)« less

SU-C-201-04: Noise and Temporal Resolution in a Near Real-Time 3D Dosimeter

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

Rilling, M; Centre de recherche sur le cancer, Universite Laval, Quebec City, QC; Radiation oncology department, CHU de Quebec, Quebec City, QC

Purpose: To characterize the performance of a real-time three-dimensional scintillation dosimeter in terms of signal-to-noise ratio (SNR) and temporal resolution of 3D dose measurements. This study quantifies its efficiency in measuring low dose levels characteristic of EBRT dynamic treatments, and in reproducing field profiles for varying multileaf collimator (MLC) speeds. Methods: The dosimeter prototype uses a plenoptic camera to acquire continuous images of the light field emitted by a 10×10×10 cm{sup 3} plastic scintillator. Using EPID acquisitions, ray tracing-based iterative tomographic algorithms allow millimeter-sized reconstruction of relative 3D dose distributions. Measurements were taken at 6MV, 400 MU/min with the scintillatormore » centered at the isocenter, first receiving doses from 1.4 to 30.6 cGy. Dynamic measurements were then performed by closing half of the MLCs at speeds of 0.67 to 2.5 cm/s, at 0° and 90° collimator angles. A reference static half-field was obtained for measured profile comparison. Results: The SNR steadily increases as a function of dose and reaches a clinically adequate plateau of 80 at 10 cGy. Below this, the decrease in light collected and increase in pixel noise diminishes the SNR; nonetheless, the EPID acquisitions and the voxel correlation employed in the reconstruction algorithms result in suitable SNR values (>75) even at low doses. For dynamic measurements at varying MLC speeds, central relative dose profiles are characterized by gradients at %D{sub 50} of 8.48 to 22.7 %/mm. These values converge towards the 32.8 %/mm-gradient measured for the static reference field profile, but are limited by the dosimeter’s current acquisition rate of 1Hz. Conclusion: This study emphasizes the efficiency of the 3D dose distribution reconstructions, while identifying limits of the current prototype’s temporal resolution in terms of dynamic EBRT parameters. This work paves the way for providing an optimized, second-generational real-time 3D scintillation dosimeter capable of highly efficient and precise dose measurements. The presenting author is financially supported by an Alexander-Graham Bell doctoral scholarship from the Natural Sciences and Engineering Research Council of Canada (NSERC).« less

Investigating a Potential Auxin-Related Mode of Hormetic/Inhibitory Action of the Phytotoxin Parthenin.

PubMed

Belz, Regina G

2016-01-01

Parthenin is a metabolite of Parthenium hysterophorus and is believed to contribute to the weed's invasiveness via allelopathy. Despite the potential of parthenin to suppress competitors, low doses stimulate plant growth. This biphasic action was hypothesized to be auxin-like and, therefore, an auxin-related mode of parthenin action was investigated using two approaches: joint action experiments with Lactuca sativa, and dose-response experiments with auxin/antiauxin-resistant Arabidopsis thaliana genotypes. The joint action approach comprised binary mixtures of subinhibitory doses of the auxin 3-indoleacetic acid (IAA) mixed with parthenin or one of three reference compounds [indole-3-butyric acid (IBA), 2,3,5-triiodobenzoic acid (TIBA), 2-(p-chlorophenoxy)-2-methylpropionic acid (PCIB)]. The reference compounds significantly interacted with IAA at all doses, but parthenin interacted only at low doses indicating that parthenin hormesis may be auxin-related, in contrast to its inhibitory action. The genetic approach investigated the response of four auxin/antiauxin-resistant mutants and a wildtype to parthenin or two reference compounds (IAA, PCIB). The responses of mutant plants to the reference compounds confirmed previous reports, but differed from the responses observed for parthenin. Parthenin stimulated and inhibited all mutants independent of resistance. This provided no indication for an auxin-related action of parthenin. Therefore, the hypothesis of an auxin-related inhibitory action of parthenin was rejected in two independent experimental approaches, while the hypothesis of an auxin-related stimulatory effect could not be rejected.

SU-F-T-461: Dosimetric Evaluation of Indigenous Farmer Type Chamber FAR65- GB for Reference Dosimetry of FFF MV Photon Beam

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

Patwe, P; Mhatre, V; Dandekar, P

Purpose: Indigenous Farmer type chamber FAR 65 GB is a reference class 0.6 cc ion chamber. It can be used for dosimetric evaluation of photon and high energy electron beams. We studied dosimetric characteristics of the chamber for 6MV and 10MV Flattening filter free FFF photon beams available on trueBEAM STx Linac. Methods: The study was carried out on trueBEAM STx Linac having 6 and 10 MV FFF photon beam with maximum dose rate 1400 and 2400 MU per min respectively. The dosimetric device to be evaluated is Rosalina Instruments FAR 65-GB Ion Chamber with active volume 0.65 cc, totalmore » active length 23.1cm, inner diameter of cylinder 6.2mm, wall thickness 0.4mm, inner electrode diameter 1mm. Inner and outer electrodes are made from Aluminium 2.7 gm per cc and graphite 1.82 gm per cc respectively. The ion chamber was placed along central axis of beam at 10cm depth and irradiated for 10cm × 10cm field size at SAD of 100 cm in plastic phantom. We studied Precision, Dose Linearity, Dose Rate dependence, directional dependence, Recombination effect. Recombination effect was determined using standard two-voltage method. Results: 1. Measurements were reproducible std deviation of 0.0105 and type A uncertainty 0.003265 under same set of reference conditions 2. Chamber exhibit dose linearity over a wider dose range. 3. Chamber shows dose rate independence for all available dose rate range. 4. Response of chamber with the angle of incidence of radiation is constant. 5. Recombination correction factors were 1.01848 and 1.02537 for dose rate 1400 and 2400 MU per min resp. Conclusion: Our study reveals that the chamber is prone to saturation effect at dose rate of 2400 MU per min. FAR 65-GB can be used for reference dosimetry of FFF MV photon beam with proper calculation of recombination effect.« less

Duration of post-vaccination immunity to yellow fever in volunteers eight years after a dose-response study.

PubMed

de Menezes Martins, Reinaldo; Maia, Maria de Lourdes S; de Lima, Sheila Maria Barbosa; de Noronha, Tatiana Guimarães; Xavier, Janaina Reis; Camacho, Luiz Antonio Bastos; de Albuquerque, Elizabeth Maciel; Farias, Roberto Henrique Guedes; da Matta de Castro, Thalita; Homma, Akira

2018-06-27

In 2009, Bio-Manguinhos conducted a dose-response study with the yellow fever vaccine, administering the vaccine in the usual mean dose of 27,476 IU (full dose, reference) and in tapered doses (10,447 IU, 3013 IU, 587 IU, 158 IU, and 31 IU) by the usual subcutaneous route and usual volume (0.5 mL). Tapered doses were obtained by dilution in the manufacturer's laboratory, and the test batches presented industrial quality. Doses down to 587 IU showed similar immunogenicity to the full dose (27,476, reference), while the 158 IU and 31 IU doses displayed lower immunogenicity. Seropositivity was maintained at 10 months, except in the group that received the 31 IU dose. The current study aims to determine whether yellow fever seropositivity was maintained eight years after YF vaccination in non-revaccinated individuals. According to the current study's results, seropositivity was maintained in 85% of 318 participants and was similar across groups. The findings support the use of the yellow fever vaccine in fractional doses during outbreaks, but each fractional dose should have at least 587 IU. This study also supports the minimum dose required by WHO, 1000 IU. Clinicaltrials.gov NCT 03338231. Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.

A patient with Cushing disease lateralizing a pituitary adenoma by inferior petrosal sinus sampling using desmopressin: a case report.

PubMed

Lim, Joo Hee; Kim, Soo Jung; Jung, Mo Kyung; Kim, Ki Eun; Kwon, Ah Reum; Chae, Hyun Wook; Kim, Duk Hee; Kim, Ho-Seong

2016-03-01

A 14-year-old girl was referred for evaluation of the etiology of Cushing syndrome. During the previous 2 years, she had experienced weight gain, secondary amenorrhea, growth retardation, and back pain. Random serum cortisol level, 24-hour urinary free cortisol excretion, and overnight and low-dose dexamethasone suppression tests suggested Cushing syndrome. Midnight adrenocorticotropic hormone (ACTH) level and high-dose dexamethasone suppression test confirmed Cushing disease. Pituitary magnetic resonance imaging was suspicious for microadenoma. To eliminate ectopic ACTH syndrome, and lateralize the pituitary tumor, inferior petrosal sinus sampling (IPSS) was performed by desmopressin use to stimulate ACTH. Finally, the patient was diagnosed with Cushing disease due to ACTH-secreting pituitary microadenoma, lateralized to the left side; subsequently underwent transsphenoidal surgery. Here we report a case of a 14-year-old girl diagnosed with Cushing disease with a pituitary tumor lateralized by IPSS using desmopressin, which is very rare in pediatric Cushing disease.

Basic principles of molecular effects of irradiation.

PubMed

Selzer, Edgar; Hebar, Alexandra

2012-02-01

In order to understand the consequences of radiation a thorough understanding of the radiobiological mechanisms of the molecular up to the clinical level is of importance. Radiobiology therefore combines the basic principles of physics as well as biology and medicine and is concerned with the action of radiation from the subcellular level up to the living organism. Topics of interest and relevance are covered in much more broadness as is possible in the short following article in the literature to which the interested reader is referred to. Classical books in this field were written by Steel et al. (1989) as well as by Hall (1994). Topics usually covered by radiobiological reviews are the classification of different types of radiation, cell cycle dependency of radiation effects, types of radiation damage and cell death, dose response curves, measurement of radiation damage, the oxygen effect, relative biological effectiveness, the influence of dose rate, and several other important research areas. This short overview will concentrate on a subset of radiobiological topics of high importance and relative novelty.

Reducing radiation dose to the female breast during conventional and dedicated breast computed tomography

NASA Astrophysics Data System (ADS)

Rupcich, Franco John

The purpose of this study was to quantify the effectiveness of techniques intended to reduce dose to the breast during CT coronary angiography (CTCA) scans with respect to task-based image quality, and to evaluate the effectiveness of optimal energy weighting in improving contrast-to-noise ratio (CNR), and thus the potential for reducing breast dose, during energy-resolved dedicated breast CT. A database quantifying organ dose for several radiosensitive organs irradiated during CTCA, including the breast, was generated using Monte Carlo simulations. This database facilitates estimation of organ-specific dose deposited during CTCA protocols using arbitrary x-ray spectra or tube-current modulation schemes without the need to run Monte Carlo simulations. The database was used to estimate breast dose for simulated CT images acquired for a reference protocol and five protocols intended to reduce breast dose. For each protocol, the performance of two tasks (detection of signals with unknown locations) was compared over a range of breast dose levels using a task-based, signal-detectability metric: the estimator of the area under the exponential free-response relative operating characteristic curve, AFE. For large-diameter/medium-contrast signals, when maintaining equivalent AFE, the 80 kV partial, 80 kV, 120 kV partial, and 120 kV tube-current modulated protocols reduced breast dose by 85%, 81%, 18%, and 6%, respectively, while the shielded protocol increased breast dose by 68%. Results for the small-diameter/high-contrast signal followed similar trends, but with smaller magnitude of the percent changes in dose. The 80 kV protocols demonstrated the greatest reduction to breast dose, however, the subsequent increase in noise may be clinically unacceptable. Tube output for these protocols can be adjusted to achieve more desirable noise levels with lesser dose reduction. The improvement in CNR of optimally projection-based and image-based weighted images relative to photon-counting was investigated for six different energy bin combinations using a bench-top energy-resolving CT system with a cadmium zinc telluride (CZT) detector. The non-ideal spectral response reduced the CNR for the projection-based weighted images, while image-based weighting improved CNR for five out of the six investigated bin combinations, despite this non-ideal response, indicating potential for image-based weighting to reduce breast dose during dedicated breast CT.

Effect of Age at Vaccination on Rotavirus Vaccine Effectiveness in Bolivian Infants.

PubMed

Burke, Rachel M; Tate, Jacqueline E; Pringle, Kimberly D; Patel, Manish; De Oliveira, Lucia H; Parashar, Umesh D

2018-01-16

Rotavirus vaccines are less effective in developing countries versus developed countries. One hypothesis for this difference in performance is that higher levels of maternal antibodies in developing countries may interfere with vaccine response, suggesting that delayed dosing could be beneficial. The present analysis aims to assess whether rotavirus vaccine effectiveness (VE) varies by age at vaccination during routine use in Bolivia. Data were merged from two post-licensure evaluations of monovalent rotavirus vaccine (RV1) in Bolivia, where two doses of RV1 are recommended at two and four months of age. For each dose, children were classified as receiving each dose "early," "on-time," or "late." Stratified unconditional logistic regression models were used to estimate VE, using unvaccinated children as the referent. VE was calculated as (1 - odds ratio) x 100%. Models were adjusted for hospital, age, and time since RV1 introduction (via including terms for month and year of birth). VE for two doses of RV1 tended to be higher in infants receiving the first dose early (VE 92%; 95% confidence interval [CI] [70%, 98%]), when compared to infants receiving their first dose on time (72% [62%, 81%]) or late (68% [51%, 79%]). Estimates of VE were not substantially different when comparing children by age at second dose (early: VE 76% [50%, 89%]; on time: VE 70% [50%, 89%]; late: VE 75% [60%, 84%]), including all children. Our results indicate that early administration may improve VE and support the current WHO recommendations for the RV1 schedule.

Radiation dose delivery verification in the treatment of carcinoma-cervix

NASA Astrophysics Data System (ADS)

Shrotriya, D.; Kumar, S.; Srivastava, R. N. L.

2015-06-01

The accurate dose delivery to the clinical target volume in radiotherapy can be affected by various pelvic tissues heterogeneities. An in-house heterogeneous woman pelvic phantom was designed and used to verify the consistency and computational capability of treatment planning system of radiation dose delivery in the treatment of cancer cervix. Oncentra 3D-TPS with collapsed cone convolution (CCC) dose calculation algorithm was used to generate AP/PA and box field technique plan. the radiation dose was delivered by Primus Linac (Siemens make) employing high energy 15 MV photon beam by isocenter technique. A PTW make, 0.125cc ionization chamber was used for direct measurements at various reference points in cervix, bladder and rectum. The study revealed that maximum variation between computed and measured dose at cervix reference point was 1% in both the techniques and 3% and 4% variation in AP/PA field and 5% and 4.5% in box technique at bladder and rectum points respectively.

Individual external doses below the lowest reference level of 1 mSv per year five years after the 2011 Fukushima nuclear accident among all children in Soma City, Fukushima: A retrospective observational study

PubMed Central

Murakami, Michio; Nomura, Shuhei; Morita, Tomohiro; Nishikawa, Yoshitaka; Leppold, Claire; Kato, Shigeaki; Kami, Masahiro

2017-01-01

After the 2011 Fukushima Daiichi nuclear power plant accident, little information has been available on individual doses from external exposure among residents living in radioactively contaminated areas near the nuclear plant; in the present study we evaluated yearly changes in the doses from external exposure after the accident and the effects of decontamination on external exposure. This study considered all children less than 16 years of age in Soma City, Fukushima who participated in annual voluntary external exposure screening programs during the five years after the accident (n = 5,363). In total, 14,405 screening results were collected. The median participant age was eight years. The geometric mean levels of annual additional doses from external exposure attributable to the Fukushima accident, decreased each year: 0.60 mSv (range: not detectable (ND)–4.29 mSv), 0.37 mSv (range: ND–3.61 mSv), 0.22 mSv (range: ND–1.44 mSv), 0.20 mSv (range: ND–1.87 mSv), and 0.17 mSv (range: ND–0.85 mSv) in 2011, 2012, 2013, 2014, and 2015, respectively. The proportion of residents with annual additional doses from external exposure of more than 1 mSv dropped from 15.6% in 2011 to zero in 2015. Doses from external exposure decreased more rapidly than those estimated from only physical decay, even in areas without decontamination (which were halved in 395 days from November 15, 2011), presumably due to the weathering effects. While the ratios of geometric mean doses immediately after decontamination to before were slightly lower than those during the same time in areas without decontamination, annual additional doses reduced by decontamination were small (0.04–0.24 mSv in the year of immediately after decontamination was completed). The results of this study showed that the levels of external exposure among Soma residents less than 16 years of age decreased during the five years after the Fukushima Daiichi nuclear power plant accident. Decontamination had only limited and temporal effects on reducing individual external doses. PMID:28235009

Organ and effective dose coefficients for cranial and caudal irradiation geometries: Neutrons

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

Veinot, K. G.; Eckerman, K. F.; Hertel, N. E.

Dose coefficients based on the recommendations of International Commission on Radiological Protection (ICRP) Publication 103 were reported in ICRP Publication 116, the revision of ICRP Publication 74 and ICRU Publication 57 for the six reference irradiation geometries: anterior–posterior, posterior–anterior, right and left lateral, rotational and isotropic. In this work, dose coefficients for neutron irradiation of the body with parallel beams directed upward from below the feet (caudal) and downward from above the head (cranial) using the ICRP 103 methodology were computed using the MCNP 6.1 radiation transport code. The dose coefficients were determined for neutrons ranging in energy from 10more » –9 MeV to 10 GeV. Here, at energies below about 500 MeV, the cranial and caudal dose coefficients are less than those for the six reference geometries reported in ICRP Publication 116.« less

Organ and effective dose coefficients for cranial and caudal irradiation geometries: Neutrons

DOE PAGES

Veinot, K. G.; Eckerman, K. F.; Hertel, N. E.; ...

2016-08-29

Dose coefficients based on the recommendations of International Commission on Radiological Protection (ICRP) Publication 103 were reported in ICRP Publication 116, the revision of ICRP Publication 74 and ICRU Publication 57 for the six reference irradiation geometries: anterior–posterior, posterior–anterior, right and left lateral, rotational and isotropic. In this work, dose coefficients for neutron irradiation of the body with parallel beams directed upward from below the feet (caudal) and downward from above the head (cranial) using the ICRP 103 methodology were computed using the MCNP 6.1 radiation transport code. The dose coefficients were determined for neutrons ranging in energy from 10more » –9 MeV to 10 GeV. Here, at energies below about 500 MeV, the cranial and caudal dose coefficients are less than those for the six reference geometries reported in ICRP Publication 116.« less

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

Shrotriya, D., E-mail: shrotriya2007@gmail.com; Srivastava, R. N. L.; Kumar, S.

The accurate dose delivery to the clinical target volume in radiotherapy can be affected by various pelvic tissues heterogeneities. An in-house heterogeneous woman pelvic phantom was designed and used to verify the consistency and computational capability of treatment planning system of radiation dose delivery in the treatment of cancer cervix. Oncentra 3D-TPS with collapsed cone convolution (CCC) dose calculation algorithm was used to generate AP/PA and box field technique plan. the radiation dose was delivered by Primus Linac (Siemens make) employing high energy 15 MV photon beam by isocenter technique. A PTW make, 0.125cc ionization chamber was used for directmore » measurements at various reference points in cervix, bladder and rectum. The study revealed that maximum variation between computed and measured dose at cervix reference point was 1% in both the techniques and 3% and 4% variation in AP/PA field and 5% and 4.5% in box technique at bladder and rectum points respectively.« less

Neutron and gamma-ray dose measurements at various distances from the Little Boy replica

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

Huntzinger, C.J.; Hankins, D.E.

We measured neutron and gamma-ray dose rates at various distances from the Little Boy-Comet Critical Assembly at Los Alamos National Laboratory (LANL) in April of 1983. The Little Boy-Comet Assembly is a replica of the atomic weapon detonated over Hiroshima, designed to be operated at various steady-state power levels. The selected distances for measurement ranged from 107 m to 567 m. Gamma-ray measurements were made with a Reuter-Stokes environmental ionization chamber which has a sensitivity of 1.0 ..mu..R/hour. Neutron measurements were made with a pulsed-source remmeter which has a sensitivity of 0.1 ..mu..rem/hour, designed and built at Lawrence Livermore Nationalmore » Laboratory (LLNL). 12 references, 7 figures, 6 tables.« less

Urinary chromium concentrations in humans following ingestion of safe doses of hexavalent and trivalent chromium: Implications for biomonitoring

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

Finley, B.L.; Scott, P.K.; Norton, R.L.

1996-08-09

This study evaluates the significance of increased urinary chromium concentrations as a marker of chromium exposure and potential health risk. Six human volunteers ingested trivalent chromium [Cr(III)] and hexavalent chromium [Cr(VI)] at doses that are known to be safe but higher than typical levels. The following dosing regimen was used: d 1-7, 200 {mu}g/d chromium picolinate; d 8-10, Cr(VI) ingestion at the U.S. Environmental Protection Agency (EPA) reference dose (RfD) of 0.005 mg/kg/d; d 11-13, no dose; d 14-16, Cr(III) ingestion at the U.S. EPA RfD of 1.0 mg/kg/d; and 17-18, postdose. Findings are as follows: (1) ingestion of 200more » {mu}g/d of chromium picolinate yielded significantly elevated urine concentrations such that each participant routinely exceeded background, (2) ingestion of the Cr(VI) RfD (0.005 mg/kg/d) yielded individual mean urinary chromium levels (1.2-2.3 {mu}g/L) and a pooled mean urinary chromium level (2.4 {mu}g/L) that significantly exceeded background, and (3) ingestion of the Cr(III) RfD yielded no significantly exceeded background, and (3) ingestion of the Cr(III) RfD yielded no significant increase in urinary chromium concentrations, indicating that little, if any, absorption occurred. Our work identified three critical issues that need to be accounted for in any future studies that will use urinary chromium as a marker of exposure. First, a minimum urinary chromium concentration of approximately 2 {mu}g/L should be used as a screening level to critically identify individuals who may have experienced elevated exposures to chromium. Second, if Cr(III) levels in soils are known to be less than 80,000 ppm and the Cr(III) is insoluble, urinary chromium concentrations are not an appropriate marker of exposure. Third, newer forms of chromium supplements that contain organic forms of Cr(III) must be considered potential confounders and their contribution to residential chromium uptake must be carefully evaluated. 19 refs., 7 figs., 3 tabs.« less

Image quality evaluation and patient dose assessment of medical fluoroscopic X-ray systems: a national study.

PubMed

Economides, S; Hourdakis, C J; Kalivas, N; Kalathaki, M; Simantirakis, G; Tritakis, P; Manousaridis, G; Vogiatzi, S; Kipouros, P; Boziari, A; Kamenopoulou, V

2008-01-01

This study presents the results from a survey conducted by the Greek Atomic Energy Commission (GAEC), during the period 1998-2003, in 530 public and private owned fluoroscopic X-ray systems in Greece. Certain operational parameters for conventional and remote control systems were assessed, according to a quality control protocol developed by GAEC on the basis of the current literature. Public (91.5%) and private (81.5%) owned fluoroscopic units exhibit high-contrast resolution values over 1 lp mm(-1). Moreover, 88.5 and 87.1% of the fluoroscopic units installed in the public and private sector, respectively, present Maximum Patient Entrance Kerma Rate values lower than 100 mGy min(-1). Additionally, 68.3% of the units assessed were found to perform within the acceptance limits. Finally, the third quartile of the Entrance Surface Dose Rate distribution was estimated according to the Dose Reference Level definition and found equal to 35 mGy min(-1).

Oligodendroglial response to ionizing radiation: Dose and dose-rate response

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

Levy, R.P.

1991-01-01

An in vitro system using neuroglia from neonatal rat brain was developed to examining the morphologic, immunocytochemical and biochemical response of oligodendroglia to ionizing radiation. Following acute [gamma]-radiation at day-in-culture (DIC) 8, oligodendrocyte counts at DIC 14 were 55% to 65% of control values after 2 Gy, and 29% to 36% after 5 Gy. Counts increased to near-normal levels at DIC 21 in the 2 Gy group and to 75% of normal in the 5 Gy group. Myelin basic protein levels (MBP) at DIC 14 were 60% of control values after 2 Gy, and 40% after 5 Gy. At DICmore » 21, MBP after 2 Gy was 45% greater than that observed at DIC 14, but MBP, as a fraction of age-matched control values, dropped from 60% to 50%. Following 5 Gy, absolute MBP changed little between DIC 14 and DIC 21, but decreased from 40% to 25% of control cultures. It was concluded that oligodendrocytes in irradiated cultures had significantly lower functional capacity than did unirradiated controls. The response to split-dose irradiation indicated that nearly all sublethal damage in the oligodendrocyte population (and its precursors) was repaired within 3 h to 4 h. At DIC 14, the group irradiated in a single fraction had significantly lower oligodendrocyte counts than any group given split doses; all irradiated cultures had marked depression of MBP synthesis, but to significant differences referable to time interval between doses. At DIC 21, cultures irradiated at intervals of 0 h to 2 h had similar oligodendrocyte counts to one another, but these counts were significantly lower than in cultures irradiated at intervals of 4 h to 6 h; MBP levels remained depressed at DIC 21 for all irradiated cultures. The oligodendrocyte response to dose rate (0.03 to 1.97 Gy/min) was evaluated at DIC 14 and DIC 21. Exposure at 0.03 Gy/min suppressed oligodendrocyte counts at DIC 21 less than did higher dose rates in 5-Gy irradiated cultures.« less

The albumin-exendin-4 recombinant protein E2HSA improves glycemic control and β-cell function in spontaneous diabetic KKAy mice.

PubMed

Li, Caina; Hou, Shaocong; Liu, Shuainan; Huan, Yi; Sun, Sujuan; Liu, Quan; Shen, Zhufang

2017-06-19

E2HSA is a genetic fusion protein that consists of two tandem exendin-4 molecules that are covalently bonded to recombinant human serum albumin via a peptide linker. Previous studies have demonstrated that E2HSA significantly decreased blood glucose levels, improved β-cell function and promoted β-cell proliferation in diabetic db/dB mice. This study aimed to evaluate the benefits of E2HSA on glucose and lipid metabolism in a spontaneous diabetes animal model, KKAy mice. E2HSA was acutely administered at doses of 1, 3 and 9 mg/kg by subcutaneous injection in diabetic KKAy mice with exendin-4 (2 μg/kg) as a positive reference, and then the non-fasting blood glucose and food intake levels were dynamically monitored. In addition, different doses of E2HSA were injected once daily, as well as with exendin-4 twice daily, for 7 weeks to evaluate the effect on glucose and lipid metabolism, as well as the body weight, food and water intake. Single injection of E2HSA decreased non-fasting blood glucose and food intake levels in a dose-dependent manner for 4 days and 2 days, respectively. Repeated injections with E2HSA significantly decreased variations in blood glucose levels with a reduction of HbA1c levels by 1.6% at a 9 mg/kg dose, simultaneously increased fasting blood insulin levels, inhibited fasting blood glucagon levels, improved the impaired oral glucose tolerance and enhanced glucose infusion rate, which is the gold standard for evaluating β-cell function. Moreover, repeated injections with E2HSA also ameliorated the dyslipidemia and reduced body weight, food and water intake in diabetic KKAy mice. E2HSA significantly reduced blood glucose levels over a prolonged duration, enhanced β-cell function, and ameliorated dyslipidemia and obesity in diabetic KKAy mice. Thus, E2HSA may be a new candidate for the treatment of type 2 diabetes.

[Prevalence and influence factors of hypertension among mechanic factory workers].

PubMed

Pang, Li-Juan; Chen, Li-Zhang; Fu, Ben-Yan

2005-06-01

To determine the status and influence factors of hypertension on mechanic factory workers and to provide reference for further hypertension prevention and control. A cross-sectional study on 1205 workers (exposed to different noise levels) in Hunan was carried out by using questionaire and measuring the blood pressure of the workers and the noise exposure level in the workplace. The prevalence and the influence factors of hypertension among mechanic factory workers were analysed. The hypertension prevalence was 12.1%. Logistic regression analysis showed the body weight index (BMI), age, and history of hypertension in parents and accumulative noise dose levels influenced the hypertension prevalence. Controlling the body weight, reducing alcohol consumption, decreasing the sound pressure level in workshops and advocating healthy diet may reduce the prevalence rate of hypertension among mechanic factory workers.

Persistent threat of lead: medical and sociological issues

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

Needleman, H.L.

1988-12-01

Lead exposure is an ancient malady. Its history serves as a useful paradigm through which to understand many other pollutants that our technological society has inserted into the human environment and may guide preventive steps for other agents. Lead poisoning was first recognized in workers exposed to high doses. The discovery of childhood toxicity occurred a century ago in Australia, when children with striking symptoms of paralysis, ophthalmoplegia, or meningitis were found to be highly lead exposed. Encephalopathy generally occurs at blood lead levels of 80 micrograms/dL or more, but unequivocal brain damage has been demonstrated at doses well belowmore » this level. At lower doses, the neurocognitive effects of lead are expressed as diminished psychometric intelligence, attention deficits, conduct problems, alterations in the electroencephalogram, school failure, and increased referral rates for special needs. Careful epidemiologic studies, which have controlled for the important confounders, have set the effect level at 10-15 micrograms/dL. Elegant animal studies in which confounding is not an issue have confirmed these findings. Although blood lead levels in the population have dropped over time for a number of reasons, there are some 3-4 million American children with blood lead levels of more than 15 micrograms/dL. Biochemical and functional changes have been demonstrated in the heme biosynthetic pathway and in the renal, cardiovascular, endocrine, immune, and nervous systems. The threshold for effect depends on the sensitivity of the methods used. A no-effect level has not been found. Further, this is not a disease of the poor alone. But the poor are exposed to much more lead than are the more economically favored. Deficiencies in body calcium, zinc, iron, and protein stores are associated with increased uptake. Optimizing nutrition enhances the resistance to lead. 110 references.« less

A Novel Pairwise Comparison-Based Method to Determine Radiation Dose Reduction Potentials of Iterative Reconstruction Algorithms, Exemplified Through Circle of Willis Computed Tomography Angiography.

PubMed

Ellmann, Stephan; Kammerer, Ferdinand; Brand, Michael; Allmendinger, Thomas; May, Matthias S; Uder, Michael; Lell, Michael M; Kramer, Manuel

2016-05-01

The aim of this study was to determine the dose reduction potential of iterative reconstruction (IR) algorithms in computed tomography angiography (CTA) of the circle of Willis using a novel method of evaluating the quality of radiation dose-reduced images. This study relied on ReconCT, a proprietary reconstruction software that allows simulating CT scans acquired with reduced radiation dose based on the raw data of true scans. To evaluate the performance of ReconCT in this regard, a phantom study was performed to compare the image noise of true and simulated scans within simulated vessels of a head phantom. That followed, 10 patients scheduled for CTA of the circle of Willis were scanned according to our institute's standard protocol (100 kV, 145 reference mAs). Subsequently, CTA images of these patients were reconstructed as either a full-dose weighted filtered back projection or with radiation dose reductions down to 10% of the full-dose level and Sinogram-Affirmed Iterative Reconstruction (SAFIRE) with either strength 3 or 5. Images were marked with arrows pointing on vessels of different sizes, and image pairs were presented to observers. Five readers assessed image quality with 2-alternative forced choice comparisons. In the phantom study, no significant differences were observed between the noise levels of simulated and true scans in filtered back projection, SAFIRE 3, and SAFIRE 5 reconstructions.The dose reduction potential for patient scans showed a strong dependence on IR strength as well as on the size of the vessel of interest. Thus, the potential radiation dose reductions ranged from 84.4% for the evaluation of great vessels reconstructed with SAFIRE 5 to 40.9% for the evaluation of small vessels reconstructed with SAFIRE 3. This study provides a novel image quality evaluation method based on 2-alternative forced choice comparisons. In CTA of the circle of Willis, higher IR strengths and greater vessel sizes allowed higher degrees of radiation dose reduction.

[An experimental study of the anti-inflammatory action of noopept and its effect on the level of cytokines].

PubMed

Alekseeva, S V; Kovalenko, L P; Tallerova, A V; Gudasheva, T A; Durnev, A D

2012-01-01

The anti-inflammatory effects of noopept (dipeptide analog of piracetam) upon a single intraperitoneal (i.p.) administration at doses of 1, 5, and 10 mg/kg in comparison to the reference drug diclofenac (10 mg/kg, i.p.) have been studied on a model of acute exudative inflammation induced by carrageenan in outbred rats and concanavalin A (Con A) in CBA mice. The level of cytokines was studied on the lipopolysaccharide (LPS) model (single administration, 100 mg/kg, i.p.) with 5-day administration of noopept at a dose of 5 mg/kg (i.p., before endotoxin injection) in C57BL/6 mice. The administration of noopept led to a significant suppression of the inflammatory response to both carrageenan and Con A. The administration of Con A caused a 16-fold increase in the level of IL-6 interleukin in the blood serum of mice as compared to control. Noopept (5 mg/kg) reduced the level of IL-6 by a factor of 1.8 in the inflammatory response to Con A. The administration of LPS led to pronounced increase in the levels ofpro-inflammatory IL-6 and TNF-alpha in the blood serum of test mice as compared to intact animals. The course administration of noopept (5 mg/kg) significantly decreased the level of IL-6 and reduced by half the level of TNF-alpha.

An audit of therapeutic drug monitoring services of anticonvulsants at a tertiary care hospital in India.

PubMed

Taur, Santosh R; Kulkarni, Namrata B; Gogtay, Nithya J; Thatte, Urmila M

2013-04-01

Therapeutic drug monitoring (TDM) is an important adjunct to the treatment of epilepsy. However, few studies have actually correlated plasma levels of antiepileptic drugs (AEDs) with treatment response. The present audit aimed to study (i) the association between seizure control and number of AEDs, plasma AED concentration, and concomitant use of antitubercular drugs; (ii) the pattern of indications for TDM requisitions; and (iii) the association between referral for toxicity and plasma AED concentration. This observational and retrospective study was carried out to analyze the TDM data of patients referred between January 2008 and December 2011. As per the International League Against Epilepsy Task Force 2009, patients were categorized into responders and nonresponders. Plasma AED levels were interpreted as below, within, and above the reference range. Of 3206 TDM requisitions, 67% were monotherapy and 33% were 2 or more AEDs. Only 8% were responders as against 92% nonresponders. Of 95 patients on concomitant antituberculosis treatment, 72 were nonresponders, with odds ratio (95% confidence interval) 3.71 [2.19 to 6.23]. Breakthrough seizure (37%) was the most common indication followed by suspected toxicity and routine monitoring in 22% each and suspected nonadherence in 11% of the total requests. In 52% of patients, plasma levels were below the reference range, and they were equally distributed amongst responders and nonresponders. Among patients referred for suspected phenytoin toxicity, only 59% (50.6 to 67.8) had plasma concentrations above the reference range. TDM continues to remain an important tool to support dose individualization when the patient is receiving multiple AEDs or other drugs such as antitubercular medicines, to assess compliance, and to monitor and treat toxicity.

Immunoglobulin E-mediated sensitization to pine and beech dust in relation to wood dust exposure levels and respiratory symptoms in the furniture industry.

PubMed

Schlünssen, Vivi; Kespohl, Sabine; Jacobsen, Gitte; Raulf-Heimsoth, Monika; Schaumburg, Inger; Sigsgaard, Torben

2011-03-01

Wood dust exposure may cause Immunoglobulin E (IgE)-mediated allergic diseases. Our objectives were to estimate pine and beech dust sensitization rates among woodworkers and a reference group, explore the association between exposure and sensitization and between sensitization and respiratory symptoms, and finally investigate the impact of proteinogenic specific IgE (sIgE) epitopes on respiratory symptoms. In a Danish study among 52 furniture factories and 2 reference factories, we evaluated the workers' asthma and rhinitis status using questionnaires and blood samples collected from 1506 woodworkers and 195 references. Workers with asthma symptoms (N=298), a random study sample (N=399) and a random rhinitis sample (N=100) were evaluated for IgE-mediated sensitization to pine and beech dust. The prevalence of pine and beech sensitization among current woodworkers was 1.7 and 3.1%, respectively. No differences in sensitization rates were found between woodworkers and references, but the prevalence of wood dust sensitization was dose-dependently associated with the current level of wood dust exposure. No relation was observed between wood dust sensitization per se and respiratory symptoms. Only symptomatic subjects had proteinogenic IgE epitopes to pine. Increased odds ratios for sIgE based on proteinogenic epitopes to beech and respiratory symptoms were found, although they were not statistically significant. Sensitization rates to pine and beech were the same for woodworkers and references but dependent on the current wood dust exposure level. The importance of beech and pine wood sensitization is limited, but may be of clinical significance for a few workers if the IgE epitopes are proteinogenic.

Estimating Toxicity Pathway Activating Doses for High Throughput Chemical Risk Assessments

EPA Science Inventory

Estimating a Toxicity Pathway Activating Dose (TPAD) from in vitro assays as an analog to a reference dose (RfD) derived from in vivo toxicity tests would facilitate high throughput risk assessments of thousands of data-poor environmental chemicals. Estimating a TPAD requires def...

Effects of body habitus on internal radiation dose calculations using the 5-year-old anthropomorphic male models.

PubMed

Xie, Tianwu; Kuster, Niels; Zaidi, Habib

2017-07-13

Computational phantoms are commonly used in internal radiation dosimetry to assess the amount and distribution pattern of energy deposited in various parts of the human body from different internal radiation sources. Radiation dose assessments are commonly performed on predetermined reference computational phantoms while the argument for individualized patient-specific radiation dosimetry exists. This study aims to evaluate the influence of body habitus on internal dosimetry and to quantify the uncertainties in dose estimation correlated with the use of fixed reference models. The 5-year-old IT'IS male phantom was modified to match target anthropometric parameters, including body weight, body height and sitting height/stature ratio (SSR), determined from reference databases, thus enabling the creation of 125 5-year-old habitus-dependent male phantoms with 10th, 25th, 50th, 75th and 90th percentile body morphometries. We evaluated the absorbed fractions and the mean absorbed dose to the target region per unit cumulative activity in the source region (S-values) of F-18 in 46 source regions for the generated 125 anthropomorphic 5-year-old hybrid male phantoms using the Monte Carlo N-Particle eXtended general purpose Monte Carlo transport code and calculated the absorbed dose and effective dose of five 18 F-labelled radiotracers for children of various habitus. For most organs, the S-value of F-18 presents stronger statistical correlations with body weight, standing height and sitting height than BMI and SSR. The self-absorbed fraction and self-absorbed S-values of F-18 and the absorbed dose and effective dose of 18 F-labelled radiotracers present with the strongest statistical correlations with body weight. For 18 F-Amino acids, 18 F-Brain receptor substances, 18 F-FDG, 18 F-L-DOPA and 18 F-FBPA, the mean absolute effective dose differences between phantoms of different habitus and fixed reference models are 11.4%, 11.3%, 10.8%, 13.3% and 11.4%, respectively. Total body weight, standing height and sitting height have considerable effects on human internal dosimetry. Radiation dose calculations for individual subjects using the most closely matched habitus-dependent computational phantom should be considered as an alternative to improve the accuracy of the estimates.

Effects of body habitus on internal radiation dose calculations using the 5-year-old anthropomorphic male models

NASA Astrophysics Data System (ADS)

Xie, Tianwu; Kuster, Niels; Zaidi, Habib

2017-08-01

Computational phantoms are commonly used in internal radiation dosimetry to assess the amount and distribution pattern of energy deposited in various parts of the human body from different internal radiation sources. Radiation dose assessments are commonly performed on predetermined reference computational phantoms while the argument for individualized patient-specific radiation dosimetry exists. This study aims to evaluate the influence of body habitus on internal dosimetry and to quantify the uncertainties in dose estimation correlated with the use of fixed reference models. The 5-year-old IT’IS male phantom was modified to match target anthropometric parameters, including body weight, body height and sitting height/stature ratio (SSR), determined from reference databases, thus enabling the creation of 125 5-year-old habitus-dependent male phantoms with 10th, 25th, 50th, 75th and 90th percentile body morphometries. We evaluated the absorbed fractions and the mean absorbed dose to the target region per unit cumulative activity in the source region (S-values) of F-18 in 46 source regions for the generated 125 anthropomorphic 5-year-old hybrid male phantoms using the Monte Carlo N-Particle eXtended general purpose Monte Carlo transport code and calculated the absorbed dose and effective dose of five 18F-labelled radiotracers for children of various habitus. For most organs, the S-value of F-18 presents stronger statistical correlations with body weight, standing height and sitting height than BMI and SSR. The self-absorbed fraction and self-absorbed S-values of F-18 and the absorbed dose and effective dose of 18F-labelled radiotracers present with the strongest statistical correlations with body weight. For 18F-Amino acids, 18F-Brain receptor substances, 18F-FDG, 18F-L-DOPA and 18F-FBPA, the mean absolute effective dose differences between phantoms of different habitus and fixed reference models are 11.4%, 11.3%, 10.8%, 13.3% and 11.4%, respectively. Total body weight, standing height and sitting height have considerable effects on human internal dosimetry. Radiation dose calculations for individual subjects using the most closely matched habitus-dependent computational phantom should be considered as an alternative to improve the accuracy of the estimates.

IRIS Toxicological Review of Beryllium and Compounds (2008 ...

EPA Pesticide Factsheets

EPA is conducting a peer review and public comment of the scientific basis supporting the human health hazard and dose-response assessment of Beryllium that when finalized will appear on the Integrated Risk Information System (IRIS) database. An IRIS Toxicological Review of Beryllium and Compounds was published in 1988 and reassessed in 1998. The current draft (2007) only focuses on the cancer assessment and does not re-evaluate posted reference doses or reference concentrations.

The role of a microDiamond detector in the dosimetry of proton pencil beams.

PubMed

Gomà, Carles; Marinelli, Marco; Safai, Sairos; Verona-Rinati, Gianluca; Würfel, Jan

2016-03-01

In this work, the performance of a microDiamond detector in a scanned proton beam is studied and its potential role in the dosimetric characterization of proton pencil beams is assessed. The linearity of the detector response with the absorbed dose and the dependence on the dose-rate were tested. The depth-dose curve and the lateral dose profiles of a proton pencil beam were measured and compared to reference data. The feasibility of calibrating the beam monitor chamber with a microDiamond detector was also studied. It was found the detector reading is linear with the absorbed dose to water (down to few cGy) and the detector response is independent of both the dose-rate (up to few Gy/s) and the proton beam energy (within the whole clinically-relevant energy range). The detector showed a good performance in depth-dose curve and lateral dose profile measurements; and it might even be used to calibrate the beam monitor chambers-provided it is cross-calibrated against a reference ionization chamber. In conclusion, the microDiamond detector was proved capable of performing an accurate dosimetric characterization of proton pencil beams. Copyright © 2015. Published by Elsevier GmbH.

An EGSnrc Monte Carlo study of the microionization chamber for reference dosimetry of narrow irregular IMRT beamlets.

PubMed

Capote, Roberto; Sánchez-Doblado, Francisco; Leal, Antonio; Lagares, Juan Ignacio; Arráns, Rafael; Hartmann, Günther H

2004-09-01

Intensity modulated radiation therapy (IMRT) has evolved toward the use of many small radiation fields, or "beamlets," to increase the resolution of the intensity map. The size of smaller beamlets can be typically about 1-5 cm2. Therefore small ionization chambers (IC) with sensitive volumes < or = 0.1 cm3 are generally used for dose verification of IMRT treatment. The dosimetry of these narrow photon beams pertains to the so-called nonreference conditions for beam calibration. The use of ion chambers for such narrow beams remains questionable due to the lack of electron equilibrium in most of the field. The present contribution aims to estimate, by the Monte Carlo (MC) method, the total correction needed to convert the IBA-Wellhöfer NAC007 micro IC measured charge in such radiation field to the absolute dose to water. Detailed geometrical simulation of the microionization chamber was performed. The ion chamber was always positioned at a 10 cm depth in water, parallel to the beam axis. The delivered doses to air and water cavity were calculated using the CAVRZ EGSnrc user code. The 6 MV phase-spaces for Primus Clinac (Siemens) used as an input to the CAVRZnrc code were derived by BEAM/EGS4 modeling of the treatment head of the machine along with the multileaf collimator [Sánchez-Doblado et al., Phys. Med. Biol. 48, 2081-2099 (2003)] and contrasted with experimental measurements. Dose calculations were carried out for two irradiation geometries, namely, the reference 10x10 cm2 field and an irregular (approximately 2x2 cm2) IMRT beamlet. The dose measured by the ion chamber is estimated by MC simulation as a dose averaged over the air cavity inside the ion-chamber (Dair). The absorbed dose to water is derived as the dose deposited inside the same volume, in the same geometrical position, filled and surrounded by water (Dwater) in the absence of the ionization chamber. Therefore, the Dwater/Dair dose ratio is a MC direct estimation of the total correction factor needed to convert the absorbed dose in air to absorbed dose to water. The dose ratio was calculated for several chamber positions, starting from the penumbra region around the beamlet along the two diagonals crossing the radiation field. For this quantity from 0 up to a 3% difference is observed between the dose ratio values obtained within the small irregular IMRT beamlet in comparison with the dose ratio derived for the reference 10x10 cm2 field. Greater differences from the reference value up to 9% were obtained in the penumbra region of the small IMRT beamlet.

The prednisone dosage in the CHOP chemotherapy regimen for non-Hodgkin's lymphomas (NHL): is there a standard?

PubMed

Moreno, A; Colon-Otero, G; Solberg, L A

2000-01-01

Discrepancies in the quoted prednisone dosages in the regimens reported as the only standard CHOP regimen stimulated our interest in reviewing the medical literature regarding this issue and to assess whether practicing hematologists and oncologists in the U.S. are aware of the different dose schedules of prednisone in the published CHOP programs. Sixteen textbooks and chemotherapy reference books were reviewed. A MEDLINE search of English-language articles published between January 1970 and December 1998 was performed. An eight-point questionnaire was sent via e-mail with responses obtained from 421 hematology/oncology physicians in the U.S. Sixteen textbooks and chemotherapy reference books reviewed quoted only one prednisone dosage as part of the standard CHOP regimen; the prednisone dosages quoted as standard varied between publications. More than 4,000 eligible non-Hodgkin's lymphoma patients have been treated with the CHOP chemotherapy as part of 43 different clinical trials reviewed. The dosages of prednisone and prednisolone used varied among six different levels. Thirty percent (127/421) of practicing U.S. physicians were not aware of the existence of more than one prednisone dose schedule as part of the CHOP regimen. The three most frequently used dosages are 100 mg/days 1-5 (67%), 100 mg/m(2)/days 1-5 (17%), and 60 mg/m(2)/days 1-5 (13%). Discrepancies in steroid dosages used as part of the reported standard CHOP regimens are common and not well recognized in the medical literature nor by practicing U.S. hematologists/oncologists. Based on this study, a prednisone dose of 100 mg/day for five days should be considered the standard dose.

Reference air kerma rate calibration system for high dose rate Ir-192 brachytherapy sources in Taiwan

NASA Astrophysics Data System (ADS)

Chu, Wei-Han; Yuan, Ming-Chen; Lee, Jeng-Hung; Lin, Yi-Chun

2017-11-01

Ir-192 sources are widely used in brachytherapy and the number of treatments is around seven thousand for the use of the high dose rate (HDR) Ir-192 brachytherapy source per year in Taiwan. Due to its physical half-life of 73.8 days, the source should be replaced four times per year to maintain the HDR treatment mode (DDEP, 2005; Coursey et al., 1992). When doing this work, it must perform the source dose trace to assure the dose accuracy. To establish the primary measurement standard of reference air kerma rate(RAKR) for the HDR Ir-192 brachytherapy sources in Taiwan, the Institute of Nuclear Energy Research (INER) fabricated a dual spherical graphite-walled cavity ionization chambers system to directly measure the RAKR of the Ir-192 brachytherapy source. In this system, the ion-charge was accumulated by the two ionization chambers and after correction for the ion recombination, temperature, atmosphere pressure, room scattering, graphite-wall attenuation, air attenuation, source decay, stem effect, and so on. The RAKR of the Ir-192 source was obtained in the ambient conditions of 22 °C and one atmosphere. The measurement uncertainty of the system was around 0.92% in 96% confidence level (k=2.0). To verify the accuracy of the result, the source calibration comparison has been made at the National Radiation Standard Laboratory (NRSL) of INER and Physikalisch-Technische Bundesanstalt (PTB, Germany) in 2015. The ratio of the measurement results between INER and PTB, INER/PTB, was 0.998±0.027 (k=2) which showed good consistency and the performance of the system was verified.

Automation of film densitometry for application in personal monitoring.

PubMed

Taheri, M; Movafeghi, A; Rastkhah, N

2011-03-01

In this research work, a semi-automatic densitometry system has been developed for large-scale monitoring services by use of film badge dosemeters. The system consists of a charge-coupled device (CCD)-based scanner that can scan optical densities (ODs) up to 4.2, a computer vision algorithm to improve the quality of digitised films and an analyser program to calculate the necessary information, e.g. the mean OD of region of interest and radiation doses. For calibration of the system, two reference films were used. The Microtek scanner International Color Consortium (ICC) profiler is applied for determining the colour attributes of the scanner accurately and a reference of the density step tablet, Bundesanstalt für Materialforschung und-prüfung (BAM) is used for calibrating the automatic conversion of gray-level values to OD values in the range of 0.2-4.0 OD. The system contributes to achieve more objectives and reliable results. So by applying this system, we can digitise a set of 20 films at once and calculate their relative doses less than about 4 min, and meanwhile it causes to avoid disadvantages of manual process and to enhance the accuracy of dosimetry.

Organ doses for reference pediatric and adolescent patients undergoing computed tomography estimated by Monte Carlo simulation

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

Lee, Choonsik; Kim, Kwang Pyo; Long, Daniel J.

Purpose: To establish an organ dose database for pediatric and adolescent reference individuals undergoing computed tomography (CT) examinations by using Monte Carlo simulation. The data will permit rapid estimates of organ and effective doses for patients of different age, gender, examination type, and CT scanner model. Methods: The Monte Carlo simulation model of a Siemens Sensation 16 CT scanner previously published was employed as a base CT scanner model. A set of absorbed doses for 33 organs/tissues normalized to the product of 100 mAs and CTDI{sub vol} (mGy/100 mAs mGy) was established by coupling the CT scanner model with age-dependentmore » reference pediatric hybrid phantoms. A series of single axial scans from the top of head to the feet of the phantoms was performed at a slice thickness of 10 mm, and at tube potentials of 80, 100, and 120 kVp. Using the established CTDI{sub vol}- and 100 mAs-normalized dose matrix, organ doses for different pediatric phantoms undergoing head, chest, abdomen-pelvis, and chest-abdomen-pelvis (CAP) scans with the Siemens Sensation 16 scanner were estimated and analyzed. The results were then compared with the values obtained from three independent published methods: CT-Expo software, organ dose for abdominal CT scan derived empirically from patient abdominal circumference, and effective dose per dose-length product (DLP). Results: Organ and effective doses were calculated and normalized to 100 mAs and CTDI{sub vol} for different CT examinations. At the same technical setting, dose to the organs, which were entirely included in the CT beam coverage, were higher by from 40 to 80% for newborn phantoms compared to those of 15-year phantoms. An increase of tube potential from 80 to 120 kVp resulted in 2.5-2.9-fold greater brain dose for head scans. The results from this study were compared with three different published studies and/or techniques. First, organ doses were compared to those given by CT-Expo which revealed dose differences up to several-fold when organs were partially included in the scan coverage. Second, selected organ doses from our calculations agreed to within 20% of values derived from empirical formulae based upon measured patient abdominal circumference. Third, the existing DLP-to-effective dose conversion coefficients tended to be smaller than values given in the present study for all examinations except head scans. Conclusions: A comprehensive organ/effective dose database was established to readily calculate doses for given patients undergoing different CT examinations. The comparisons of our results with the existing studies highlight that use of hybrid phantoms with realistic anatomy is important to improve the accuracy of CT organ dosimetry. The comprehensive pediatric dose data developed here are the first organ-specific pediatric CT scan database based on the realistic pediatric hybrid phantoms which are compliant with the reference data from the International Commission on Radiological Protection (ICRP). The organ dose database is being coupled with an adult organ dose database recently published as part of the development of a user-friendly computer program enabling rapid estimates of organ and effective dose doses for patients of any age, gender, examination types, and CT scanner model.« less

SU-E-T-549: A Combinatorial Optimization Approach to Treatment Planning with Non-Uniform Fractions in Intensity Modulated Proton Therapy

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

Papp, D; Unkelbach, J

2014-06-01

Purpose: Non-uniform fractionation, i.e. delivering distinct dose distributions in two subsequent fractions, can potentially improve outcomes by increasing biological dose to the target without increasing dose to healthy tissues. This is possible if both fractions deliver a similar dose to normal tissues (exploit the fractionation effect) but high single fraction doses to subvolumes of the target (hypofractionation). Optimization of such treatment plans can be formulated using biological equivalent dose (BED), but leads to intractable nonconvex optimization problems. We introduce a novel optimization approach to address this challenge. Methods: We first optimize a reference IMPT plan using standard techniques that deliversmore » a homogeneous target dose in both fractions. The method then divides the pencil beams into two sets, which are assigned to either fraction one or fraction two. The total intensity of each pencil beam, and therefore the physical dose, remains unchanged compared to the reference plan. The objectives are to maximize the mean BED in the target and to minimize the mean BED in normal tissues, which is a quadratic function of the pencil beam weights. The optimal reassignment of pencil beams to one of the two fractions is formulated as a binary quadratic optimization problem. A near-optimal solution to this problem can be obtained by convex relaxation and randomized rounding. Results: The method is demonstrated for a large arteriovenous malformation (AVM) case treated in two fractions. The algorithm yields a treatment plan, which delivers a high dose to parts of the AVM in one of the fractions, but similar doses in both fractions to the normal brain tissue adjacent to the AVM. Using the approach, the mean BED in the target was increased by approximately 10% compared to what would have been possible with a uniform reference plan for the same normal tissue mean BED.« less

Fiber-Coupled, Time-Gated { {Al}}_{2}{ {O}}_{3} : { {C}} Radioluminescence Dosimetry Technique and Algorithm for Radiation Therapy With LINACs

NASA Astrophysics Data System (ADS)

Magne, Sylvain; Deloule, Sybelle; Ostrowsky, Aimé; Ferdinand, Pierre

2013-08-01

An original algorithm for real-time In Vivo Dosimetry (IVD) based on Radioluminescence (RL) of dosimetric-grade Al2O3:C crystals is described and demonstrated in reference conditions with 12-MV photon beams from a Saturne 43 linear accelerator (LINAC), simulating External Beam Radiation Therapy (EBRT) treatments. During the course of irradiation, a portion of electrons is trapped within the Al2O3:C crystal while another portion recombines and generates RL, recorded on-line using an optical fiber. The RL sensitivity is dose-dependent and increases in accordance with the concentration of trapped electrons. Once irradiation is completed, the Al2O3:C crystal is reset by laser light (reusable) and the resultant OSL (Optically Stimulated Luminescence) is also collected back by the remote RL-OSL reader and finally integrated to yield the absorbed dose. During irradiation, scintillation and Cerenkov lights generated within the optical fiber (“stem effect”) are removed by a time-discrimination method involving a discriminating unit and a fiber-coupled BGO scintillator placed in the irradiation room, next to the LINAC. The RL signals were then calibrated with respect to reference dose and dose rate data using an ionization chamber (IC). The algorithm relies upon the integral of the RL and provides the accumulated dose (useful to the medical physicist) at any time during irradiation, the dose rate being derived afterwards. It is tested with both step and arbitrary dose rate profiles, manually operated from the LINAC control desk. The doses measured by RL and OSL are both compared to reference doses and deviations are about ±2% and ±1% respectively, thus demonstrating the reliability of the algorithm for arbitrary profiles and wide range of dose rates. Although the calculation was done off-line, it is amenable to real-time processing during irradiation.

Radiation dose constraints for organs at risk in neuro-oncology; the European Particle Therapy Network consensus.

PubMed

Lambrecht, Maarten; Eekers, Daniëlle B P; Alapetite, Claire; Burnet, Neil G; Calugaru, Valentin; Coremans, Ida E M; Fossati, Piero; Høyer, Morten; Langendijk, Johannes A; Romero, Alejandra Méndez; Paulsen, Frank; Perpar, Ana; Renard, Laurette; de Ruysscher, Dirk; Timmermann, Beate; Vitek, Pavel; Weber, Damien C; van der Weide, Hiske L; Whitfield, Gillian A; Wiggenraad, Ruud; Roelofs, Erik; Nyström, Petra Witt; Troost, Esther G C

2018-05-17

For unbiased comparison of different radiation modalities and techniques, consensus on delineation of radiation sensitive organs at risk (OARs) and on their dose constraints is warranted. Following the publication of a digital, online atlas for OAR delineation in neuro-oncology by the same group, we assessed the brain OAR-dose constraints in a follow-up study. We performed a comprehensive search to identify the current papers on OAR dose constraints for normofractionated photon and particle therapy in PubMed, Ovid Medline, Cochrane Library, Embase and Web of Science. Moreover, the included articles' reference lists were cross-checked for potential studies that met the inclusion criteria. Consensus was reached among 20 radiation oncology experts in the field of neuro-oncology. For the OARs published in the neuro-oncology literature, we summarized the available literature and recommended dose constraints associated with certain levels of normal tissue complication probability (NTCP) according to the recent ICRU recommendations. For those OARs with lacking or insufficient NTCP data, a proposal for effective and efficient data collection is given. The use of the European Particle Therapy Network-consensus OAR dose constraints summarized in this article is recommended for the model-based approach comparing photon and proton beam irradiation as well as for prospective clinical trials including novel radiation techniques and/or modalities. Copyright © 2018 Elsevier B.V. All rights reserved.

Six months exposure to a real life mixture of 13 chemicals' below individual NOAELs induced non monotonic sex-dependent biochemical and redox status changes in rats.

PubMed

Docea, Anca Oana; Gofita, Eliza; Goumenou, Marina; Calina, Daniela; Rogoveanu, Otilia; Varut, Marius; Olaru, Cristian; Kerasioti, Efthalia; Fountoucidou, Polyxeni; Taitzoglou, Ioannis; Zlatian, Ovidiu; Rakitskii, Valerii N; Hernandez, Antonio F; Kouretas, Dimitrios; Tsatsakis, Aristidis

2018-05-01

This study assessed the potential adverse health effects of long-term low-dose exposure to chemical mixtures simulating complex real-life human exposures. Four groups of Sprague Dawley rats were administered mixtures containing carbaryl, dimethoate, glyphosate, methomyl, methyl parathion, triadimefon, aspartame, sodium benzoate, calcium disodium ethylene diamine tetra-acetate, ethylparaben, butylparaben, bisphenol A, and acacia gum at doses of 0, 0.25, 1 or 5 times the respective Toxicological Reference Values (TRV): acceptable daily intake (ADI) or tolerable daily intake (TDI) in a 24 weeks toxicity study. Body weight gain, feed and water consumption were evaluated weekly. At 24 weeks blood was collected and biochemistry parameters and redox status markers were assessed. Adverse effects were observed on body weight gain and in hepatotoxic parameters such as the total bilirubin, alanine aminotransferase (ALT) and alkaline phosphatase (ALP), especially in low dose and affecting mainly male rats. The low dose group showed increased catalase activity both in females and males, whereas the high dose group exhibited decreased protein carbonyl and total antioxidant capacity (TAC) levels in both sex groups. Non-monotonic effects and adaptive responses on liver function tests and redox status, leading to non-linear dose-responses curves, are probably produced by modulation of different mechanisms. Copyright © 2018. Published by Elsevier Ltd.

A retrospective analysis of toxicity studies in dogs and impact on the chronic reference dose for conventional pesticide chemicals.

PubMed

Dellarco, Vicki L; Rowland, Jess; May, Brenda

2010-01-01

Prior to October 2007, the US Environmental Protection Agency (EPA) required both 13-week and 1-year studies in Beagle dogs be submitted in support of registration for pesticides. Following an extensive retrospective analysis, we (the authors) determined that the 1-year toxicity dog study should be eliminated as a requirement for pesticide registration. The present work presents this retrospective analysis of results from 13-week and 1-year dog studies for 110 conventional pesticide chemicals, representing more than 50 classes of pesticides. The data were evaluated to determine if the 13-week dog study, in addition to the long-term studies in two rodent species (mice and rats), were sufficient for the identification of no observed adverse effect levels (NOAELs) and lowest observed adverse effect levels (LOAELs) for the derivation of chronic reference doses (RfD). Only pesticides with adequate 13-week and 1-year duration studies were included in the present evaluation. Toxicity endpoints and dose-response data from 13-week and 1-year studies were compared. The analysis showed that 70 of the 110 pesticides had similar critical effects regardless of duration and had NOAELs and LOAELs within a difference of 1.5-fold of each other. For the remaining 40 pesticides, 31 had lower NOAELs and LOAELs in the 1-year study, primarily due to dose selection and spacing. In only 2% of the cases were additional toxic effects identified in the 1-year study that were not observed in the 13-week study and/or in the rodent studies. In 8% of the cases, the 1-year dog had a lower NOAEL and/or LOAEL than the 13-week study, but there would have been no regulatory impact if the 1-year dog study had not been performed because adequate data were available from the other required studies. A dog toxicity study beyond 13-weeks does not have significant impact on the derivation of a chronic RfD for pesticide risk assessment.

1983 international intercomparison of nuclear accident dosimetry systems at Oak Ridge National Laboratory

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

Swaja, R.E.; Greene, R.T.; Sims, C.S.

1985-04-01

An international intercomparison of nuclear accident dosimetry systems was conducted during September 12-16, 1983, at Oak Ridge National Laboratory (ORNL) using the Health Physics Research Reactor operated in the pulse mode to simulate criticality accidents. This study marked the twentieth in a series of annual accident dosimetry intercomparisons conducted at ORNL. Participants from ten organizations attended this intercomparison and measured neutron and gamma doses at area monitoring stations and on phantoms for three different shield conditions. Results of this study indicate that foil activation techniques are the most popular and accurate method of determining accident-level neutron doses at area monitoringmore » stations. For personnel monitoring, foil activation, blood sodium activation, and thermoluminescent (TL) methods are all capable of providing accurate dose estimates in a variety of radiation fields. All participants in this study used TLD's to determine gamma doses with very good results on the average. Chemical dosemeters were also shown to be capable of yielding accurate estimates of total neutron plus gamma doses in a variety of radiation fields. While 83% of all neutron measurements satisfied regulatory standards relative to reference values, only 39% of all gamma results satisfied corresponding guidelines for gamma measurements. These results indicate that continued improvement in accident dosimetry evaluation and measurement techniques is needed.« less

SU-F-J-214: Dose Reduction by Spatially Optimized Image Quality Via Fluence Modulated Proton CT (FMpCT)

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

De Angelis, L; Landry, G; Dedes, G

Purpose: Proton CT (pCT) is a promising imaging modality for reducing range uncertainty in image-guided proton therapy. Range uncertainties partially originate from X-ray CT number conversion to stopping power ratio (SPR) and are limiting the exploitation of the full potential of proton therapy. In this study we explore the concept of spatially dependent fluence modulated proton CT (FMpCT), for achieving optimal image quality in a clinical region of interest (ROI), while reducing significantly the imaging dose to the patient. Methods: The study was based on simulated ideal pCT using pencil beam (PB) scanning. A set of 250 MeV protons PBsmore » was used to create 360 projections of a cylindrical water phantom and a head and neck cancer patient. The tomographic images were reconstructed using a filtered backprojection (FBP) as well as an iterative algorithm (ITR). Different fluence modulation levels were investigated and their impact on the image was quantified in terms of SPR accuracy as well as noise within and outside selected ROIs, as a function of imaging dose. The unmodulated image served as reference. Results: Both FBP reconstruction and ITR without total variation (TV) yielded image quality in the ROIs similar to the reference images, for modulation down to 0.1 of the full proton fluence. The average dose was reduced by 75% for the water phantom and by 40% for the patient. FMpCT does not improve the noise for ITR with TV and modulation 0.1. Conclusion: This is the first work proposing and investigating FMpCT for producing optimal image quality for treatment planning and image guidance, while simultaneously reducing imaging dose. Future work will address spatial resolution effects and the impact of FMpCT on the quality of proton treatment plans for a prototype pCT scanner capable of list mode data acquisition. Acknowledgement: DFG-MAP DFG - Munich-Centre for Advanced Photonics (MAP)« less

International Atomic Energy Agency study with referring physicians on patient radiation exposure and its tracking: a prospective survey using a web-based questionnaire

PubMed Central

Rehani, Madan M; Berris, Theocharis

2012-01-01

Objectives To assess the following themes among referring physicians: (A) importance of acquiring information about previous diagnostic exposures; (B) knowledge about radiation doses involved, familiarity with radiation units and, age-related radiosensitivity; (C) opinion on whether patients should be provided information about radiation dose and (D) self-assessment of appropriateness of referrals. Design A prospective survey using a web-based questionnaire. Setting International survey among referring physicians. Participants Referring physicians from 28 countries. Main outcome measures Knowledge, opinion and practice of the four themes of the survey. Results All 728 responses from 28 countries (52.3% from developed and 47.7% from developing countries) indicated that while the vast majority (71.7%) of physicians feel that being aware of history of CT scans would always or mostly lead them to a better decision on referring patients for CT scans, only 43.4% often enquire about it. The majority of referring physicians (60.5%) stated that having a system that provides quick information about patient exposure history would be useful. The knowledge about radiation doses involved is poor, as only one-third (34.7%) of respondents chose the correct option of the number of chest x-rays with equivalence of a CT scan. In total, 70.9% of physicians stated that they do not feel uncomfortable when patients ask about radiation risk from CT scans they prescribe. Most physicians (85.6%) assessed that they have rarely prescribed CT scans of no clinical use in patient management. Conclusions This first ever multinational survey among referring physicians from 28 countries indicates support for a system that provides radiation exposure history of the patient, demonstrates poor knowledge about radiation doses, supports radiation risk communication with patients and mandatory provisions for justification of a CT examination. PMID:22997065

[Analysis of main risk factors causing foodborne diseases in food catering business].

PubMed

Fan, Yong-xiang; Liu, Xiu-mei; Bao, Yi-dan

2011-06-01

To study main risk factors that cause foodborne diseases in food catering business. Data from references and investigations conducted in food catering units were used to establish models which based on @Risk 4.5 with Monte Carlo method referring to food handling practice model (FHPM) to make risk assessment on factors of food contamination in food catering units. The Beta-Poisson models on dose-response relationship to Salmonella (developed by WHO/FAO and United States Department of Agriculture) and Vibrio parahaemolyticus (developed by US FDA) were used in this article to analyze the dose-response relationship of pathogens. The average probability of food poisoning by consuming Salmonella contaminated cooked meat under refrigeration was 1.96 × 10(-4) which was 1/2800 of the food under non-refrigeration (the average probability of food poisoning was 0.35 at room temperature 25°C). The average probability by consuming 6 hours stored meat under room temperature was 0.11 which was 16 times of 2 hours storage (6.79 × 10(-3)). The average probability by consuming contaminated meat without fully cooking was 1.71 × 10(-4) which was 100 times of consuming fully cooked meat (1.88 × 10(-6)). The probability growth of food poisoning by consuming Vibrio parahaemolyticus contaminated fresh seafood was proportional with contamination level and prevalence. The primary contamination level, storage temperature and time, cooking process and cross contamination are important factors of catering food safety.

A bioequivalence study of levothyroxine tablets versus an oral levothyroxine solution in healthy volunteers.

PubMed

Yannovits, N; Zintzaras, E; Pouli, A; Koukoulis, G; Lyberi, S; Savari, E; Potamianos, S; Triposkiadis, F; Stefanidis, I; Zartaloudis, E; Benakis, A

2006-01-01

Probably for genetic reasons a substantial part of the Greek population requires Levothyroxine treatment. Since commercially available Levothyroxine was first marketed, the manufacture and storage of the drug in tablet form has been complicated and difficult; and as cases of therapeutic failure have frequently been reported following treatment with this medicinal agent, quality control is an essential factor. Due to the unreliability of Levothyroxine-based commercial products, in the present study we decided to follow the Food and Drug Administration (FDA) guidelines*, and use a Levothyroxine solution as reference product. The bioavailability of the Levothyroxine sodium tablet formulation THYROHORMONE/Ni-The Ltd (0.2 mg/tab) and that of a reference oral solution (0.3 mg/100 ml) under fasting conditions were compared in an open, randomized, single-dose two-way crossover study. Twenty four healthy Caucasian volunteers (M/F=15/9, mean age=32.9+/-7.4yr) participated in the study. Bioavailability was assessed by pharmacokinetic parameters such as the area under plasma concentration-time curve from time zero up to the measurable last time point (AUC(last)) and the maximum plasma concentration (Cmax). Heparinized venous blood samples were collected pre-dose and up to a 48-hour period post-dose. Levothyroxine sodium in plasma samples was assayed by a validated electrochemiluninescent immunoassay technique. Statistical analysis showed that the post-dose thyrotropin-stimulating hormone (TSH) levels decreased significantly (p<0.05). Regarding Levothyroxine (T4), the point estimate of the test formulation to the reference formulation ratios (T/R) for AUC(last) and Cmax was 0.92 with 90% confidence limits (0.90, 0.94) and 0.93 with 90% confidence limits (0.91, 0.94), respectively. Regarding triiodo-L-thyronine (T3), the point estimate for the T/R ratios of AUC(last) and Cmax was 0.92 with 90% confidence limits (0.90, 0.95) and 0.94 with 90% confidence limits (0.92, 0.95), respectively. The 90% confidence limits for the pharmacokinetic parameters AUC(last) and Cmax lie within the acceptance limits for bioequivalence (0.80, 1.25), for both T3 and T4.

Potential antimalarial activity of Methyl Jasmonate and its effect on lipid profiles in Plasmodium Berghei infected mice.

PubMed

Oyinloye, Oladapo E; Kosoko, Ayokulehin M; Emikpe, Benjamin; Falade, Catherine O; Ademowo, Olusegun G

2015-09-01

The antimalarial activity and lipid profiles of Methyl Jasmonate (MJ) were investigated against established malaria infection in vivo using BALB/c mice. Arteether (AE) and chloroquine (CQ) were used as reference drugs while ethanol was used as the vehicle for drug delivery for MJ. Mice treated with 10 and 25 mg/kg MJ showed a remarkable reduction in percentage parasitemia by 68.3% and 78.2% on day 10(post treatment) respectively while 45.4% and 87.2% reduction in percentage parasitemia were observed in the group treated with 50 mg/kg on day 3 and 10 (post treatment) respectively. The highest mean survival time was observed in CQ followed by AE and MJ in dose-dependent manner. A progressive decrease in packed cell volume (PCV) was observed in infected untreated mice which led to the death of all the mice by day 9 (post treatment). Infected mice treated with MJ showed reduced level of HDL and LDL compared with infected untreated group. As the dose of MJ increased in infected mice cholesterol levels increased while there was reduction in triglyceride. Overall there was marked decrease in parasitemia in Plasmodium berghei infected mice treated with graded doses of MJ but appears to have reduced antimalarial activity compared with CQ and AE.

Extract of Lycopus europaeus L. reduces cardiac signs of hyperthyroidism in rats.

PubMed

Vonhoff, Christian; Baumgartner, Andreas; Hegger, Mirjam; Korte, Brigitte; Biller, Andreas; Winterhoff, Hilke

2006-02-02

Extracts from the plant Lycopus europaeus L. are traditionally used in mild forms of hyperthyroidism. High doses caused a reduction of TSH or thyroid hormone levels in animal experiments, whereas in hyperthyroid patients treated with low doses of Lycopus an improvement of cardiac symptoms was reported without major changes in TSH or thyroid hormone concentrations. Lycopus extract was tested in thyroxine treated hyperthyroid rats (0.7 mg/kg BW i.p.). Co-treatment with an hydroethanolic extract from L. europaeus L. started one week later than T4-application and lasted 5.5 weeks. As reference substance atenolol was used. The raised body temperature was reduced very effectively even by the low dose of the plant extract, whereas the reduced gain of body weight and the increased food intake remained unaffected by any treatment. No significant changes of thyroid hormone concentrations or TSH levels were observed. Lycopus extract and atenolol reduced the increased heart rate and blood pressure. The cardiac hypertrophy was alleviated significantly by both treatment regimes. beta-Adrenoceptor density in heart tissue was significantly reduced by the Lycopus extract or the beta-blocking agent showing an almost equal efficacy. Although the mode of action remains unclear, these organo-specific anti-T4-effects seem to be of practical interest, for example in patients with latent hyperthyroidism.

Heavy construction equipment noise study using dosimetry and time-motion studies

NASA Astrophysics Data System (ADS)

Spencer, Ellsworth R.; Yantek, David S.

2005-09-01

Noise-induced hearing loss continues to afflict workers in many occupational settings despite longstanding recognition of the problems and well-known methods of prevention and regulations. Sound levels associated with heavy construction equipment range from 80 to 120 dB(A) and power tools commonly used in construction produce sound levels up to 115 dB(A). The focus of the research was to determine the noise exposures of heavy construction equipment operators while documenting the workers' tasks, (i.e., hauling, moving, and/or pushing construction material). Time-motion studies were performed at the construction sites and were used to correlate the noise dosage with the work performed by equipment operators. The cumulative dose for the operator was then plotted with references to work tasks, to identify the tasks that caused the greatest noise exposure. Three construction sites were examined and located in the western Pennsylvania and eastern Ohio areas. The types of construction equipment studied included asphalt pavers, backhoes, bulldozers, compaction equipment, excavators, haul trucks, telehandlers, and wheeled loaders. The results showed that bulldozer operators consistently had the highest noise exposures, ranging from a NIOSH REL (Recommended Exposure Limit) dose of 844% to 25836% and an OSHA PEL (Permissible Exposure Limit) dose of 139% to 1397%.

Implementation of Information Management System for Radiation Safety of Personnel at the Russian Northwest Center for Radioactive Waste Management 'SevRAO' - 13131

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

Chizhov, K.; Simakov, A.; Seregin, V.

2013-07-01

The report is an overview of the information-analytical system designed to assure radiation safety of workers. The system was implemented in the Northwest Radioactive Waste Management Center 'SevRAO' (which is a branch of the Federal State Unitary Enterprise 'Radioactive Waste Management Enterprise RosRAO'). The center is located in the Northwest Russia. In respect to 'SevRAO', the Federal Medical-Biological Agency is the regulatory body, which deals with issues of radiation control. The main document to regulate radiation control is 'Reference levels of radiation factors in radioactive wastes management center'. This document contains about 250 parameters. We have developed a software toolmore » to simplify control of these parameters. The software includes: input interface, the database, dose calculating module and analytical block. Input interface is used to enter radiation environment data. Dose calculating module calculates the dose on the route. Analytical block optimizes and analyzes radiation situation maps. Much attention is paid to the GUI and graphical representation of results. The operator can enter the route at the industrial site or watch the fluctuations of the dose rate field on the map. Most of the results are presented in a visual form. Here we present some analytical tasks, such as comparison of the dose rate in some point with control levels at this point, to be solved for the purpose of radiation safety control. The program helps to identify points making the largest contribution to the collective dose of the personnel. The tool can automatically calculate the route with the lowest dose, compare and choose the best route. The program uses several options to visualize the radiation environment at the industrial site. This system will be useful for radiation monitoring services during the operation, planning of works and development of scenarios. The paper presents some applications of this system on real data over three years - from March 2009 to February 2012. (authors)« less

Can we safely administer the recommended dose of phenobarbital in very low birth weight infants?

PubMed

Oztekin, Osman; Kalay, Salih; Tezel, Gonul; Akcakus, Mustafa; Oygur, Nihal

2013-08-01

We investigated whether the recommended phenobarbital loading dose of 15-20 mg/kg with maintenance of 3-4 mg/kg/day can safely be administered to very low birth weight preterm newborns with seizures. Twenty-four convulsive preterms of <1,500 g were enrolled in the study. Phenobarbital was administered intravenously with a loading dose of 15 mg/kg in approximately 10-15 min. After 24 h, the maintenance dose of 3 mg/kg/day was administered as a single injection. Blood samples were obtained 2, 24, 48, 72, and 96 h after the phenobarbital loading dose was administered, immediately before the next phenobarbital dose was injected. None of the cases had plasma phenobarbital concentrations above the therapeutic upper limit of 40 μg/mL on the 2nd hour; one case (4.7%), on the 24th; 11 cases (45.8%), on the 48th; 15 cases (62.5%), on the 72nd; and 17 cases (70.8%), on the 96th hour. A negative correlation was detected between the serum concentrations of phenobarbital and gestational age on the 72th (p, 0.036; r, -0.608) and 96th hour (p, 0.043; r, -0.769). We suggest that particular attention should be done while administering phenobarbital in preterms, as blood levels of phenobarbital are higher than the reference ranges that those are often reached with the recommended doses in these groups of babies.

Direct measurement of a patient's entrance skin dose during pediatric cardiac catheterization

PubMed Central

Sun, Lue; Mizuno, Yusuke; Iwamoto, Mari; Goto, Takahisa; Koguchi, Yasuhiro; Miyamoto, Yuka; Tsuboi, Koji; Chida, Koichi; Moritake, Takashi

2014-01-01

Children with complex congenital heart diseases often require repeated cardiac catheterization; however, children are more radiosensitive than adults. Therefore, radiation-induced carcinogenesis is an important consideration for children who undergo those procedures. We measured entrance skin doses (ESDs) using radio-photoluminescence dosimeter (RPLD) chips during cardiac catheterization for 15 pediatric patients (median age, 1.92 years; males, n = 9; females, n = 6) with cardiac diseases. Four RPLD chips were placed on the patient's posterior and right side of the chest. Correlations between maximum ESD and dose–area products (DAP), total number of frames, total fluoroscopic time, number of cine runs, cumulative dose at the interventional reference point (IRP), body weight, chest thickness, and height were analyzed. The maximum ESD was 80 ± 59 (mean ± standard deviation) mGy. Maximum ESD closely correlated with both DAP (r = 0.78) and cumulative dose at the IRP (r = 0.82). Maximum ESD for coiling and ballooning tended to be higher than that for ablation, balloon atrial septostomy, and diagnostic procedures. In conclusion, we directly measured ESD using RPLD chips and found that maximum ESD could be estimated in real-time using angiographic parameters, such as DAP and cumulative dose at the IRP. Children requiring repeated catheterizations would be exposed to high radiation levels throughout their lives, although treatment influences radiation dose. Therefore, the radiation dose associated with individual cardiac catheterizations should be analyzed, and the effects of radiation throughout the lives of such patients should be followed. PMID:24968708

Image perception by expert readers as a function of patient skin entrance dose levels in digital radiography

NASA Astrophysics Data System (ADS)

Lehnert, T.; Korkusuz, H.; Khan, F.; Vogl, T. J.; Mack, M. G.

2008-03-01

In this study, image quality was based on required clinical criteria, in order to investigate to what degree entrance dose could be lowered and what kind of added filtration can be used without impinging on radiologist confidence levels in diagnosing. Images were taken of extremities from a cadaver using stepwise decreasing dose levels and variation of added filtration (no filtration, aluminum, aluminum/copper) under digital projection radiography (Kodak DirectView DR7500). The starting point dose level for all body parts imaged was the current x-ray technique. Two experienced and two resident radiologists were presented the images in a blinded fashion and rated each with an image quality score from 1 to 9 indicated very satisfied and 1 as very unsatisfied indicating loss of diagnostic value. The readers were not aware of which dose level and added filtration corresponded to which image. Dose levels considered were 100%, 75%, 50% and 25% of the normal and customary x-ray techniques used for the particular body part and projection. Images were reviewed on a clinical diagnostic workstation with no time limits imposed. Readers were also able to change the image presentation by adjusting the window width and level. Without added filtration image quality mean score was rated with 6.3 (dose level 100%), 6.2 (dose level 75%), 5.3 (dose level 50%) and with 4.4 (dose level 25%). An added aluminum filtration induced an image quality mean score of 6.3 (dose level 100%), 6.0 (dose level 75%), 5.1 (dose level 50%) and of 4.2 (dose level 25%). Using aluminum/copper filtration image quality mean score was rated with 6.0 (dose level 100%), 6.1 (dose level 75%), 5.0 (dose level 50%) and with 3.8 (dose level 25%). Regardless of the added filtration a differentiation between dose levels 100% and 75% was possible in 38.9%, between dose levels 75% and 50% in 66.7%, and between dose levels 50% and 25% in 70.0% of the cases. It is possible, in the case of extremities, to lower entrance doses up to 75 % of the normal value, a reduction of 25% in dose, under simultaneous use of added aluminum or aluminum/copper filtration, without comprising the diagnostic value required.

Analysis of uncertainties in Monte Carlo simulated organ dose for chest CT

NASA Astrophysics Data System (ADS)

Muryn, John S.; Morgan, Ashraf G.; Segars, W. P.; Liptak, Chris L.; Dong, Frank F.; Primak, Andrew N.; Li, Xiang

2015-03-01

In Monte Carlo simulation of organ dose for a chest CT scan, many input parameters are required (e.g., half-value layer of the x-ray energy spectrum, effective beam width, and anatomical coverage of the scan). The input parameter values are provided by the manufacturer, measured experimentally, or determined based on typical clinical practices. The goal of this study was to assess the uncertainties in Monte Carlo simulated organ dose as a result of using input parameter values that deviate from the truth (clinical reality). Organ dose from a chest CT scan was simulated for a standard-size female phantom using a set of reference input parameter values (treated as the truth). To emulate the situation in which the input parameter values used by the researcher may deviate from the truth, additional simulations were performed in which errors were purposefully introduced into the input parameter values, the effects of which on organ dose per CTDIvol were analyzed. Our study showed that when errors in half value layer were within ± 0.5 mm Al, the errors in organ dose per CTDIvol were less than 6%. Errors in effective beam width of up to 3 mm had negligible effect (< 2.5%) on organ dose. In contrast, when the assumed anatomical center of the patient deviated from the true anatomical center by 5 cm, organ dose errors of up to 20% were introduced. Lastly, when the assumed extra scan length was longer by 4 cm than the true value, dose errors of up to 160% were found. The results answer the important question: to what level of accuracy each input parameter needs to be determined in order to obtain accurate organ dose results.

Effective Dose in Nuclear Medicine Studies and SPECT/CT: Dosimetry Survey Across Quebec Province.

PubMed

Charest, Mathieu; Asselin, Chantal

2018-06-01

The aims of the current study were to draw a portrait of the delivered dose in selected nuclear medicine studies in Québec province and to assess the degree of change between an earlier survey performed in 2010 and a later survey performed in 2014. Methods: Each surveyed nuclear medicine department had to complete 2 forms: the first, about the administered activity in selected nuclear medicine studies, and the second, about the CT parameters used in SPECT/CT imaging, if available. The administered activities were converted into effective doses using the most recent conversion factors. Diagnostic reference levels were computed for each imaging procedure to obtain a benchmark for comparison. Results: The distributions of administered activity in various nuclear medicine studies, along with the corresponding distribution of the effective doses, were determined. Excluding 131 I for thyroid studies, 67 Ga-citrate for infectious workups, and combined stress and rest myocardial perfusion studies, the remainder of the 99m Tc-based studies delivered average effective doses clustered below 10 mSv. Between the 2010 survey and the 2014 survey, there was a statistically significant decrease in delivered dose from 18.3 to 14.5 mSv. 67 Ga-citrate studies for infectious workups also showed a significant decrease in delivered dose from 31.0 to 26.2 mSv. The standardized CT portion of SPECT/CT studies yielded a mean effective dose 14 times lower than the radiopharmaceutical portion of the study. Conclusion: Between 2010 and 2014, there was a significant decrease in the delivered effective dose in myocardial perfusion and 67 Ga-citrate studies. The CT portions of the surveyed SPECT/CT studies contributed a relatively small fraction of the total delivered effective dose. © 2018 by the Society of Nuclear Medicine and Molecular Imaging.

Metabolomic analysis reveals metabolic changes caused by bisphenol A in rats.

PubMed

Chen, Minjian; Zhou, Kun; Chen, Xiaojiao; Qiao, Shanlei; Hu, Yanhui; Xu, Bo; Xu, Bin; Han, Xiumei; Tang, Rong; Mao, Zhilei; Dong, Congcong; Wu, Di; Wang, Yubang; Wang, Shoulin; Zhou, Zuomin; Xia, Yankai; Wang, Xinru

2014-04-01

Bisphenol A (BPA) is a widely used material known to cause adverse effects in humans and other mammals. To date, little is known about the global metabolomic alterations caused by BPA using urinalysis. Sprague-Dawley rats were orally administrated BPA at the levels of 0, 0.5 μg/kg/day and 50 mg/kg/day covering a low dose and a reference dose for 8 weeks. We conducted a capillary electrophoresis in tandem with electrospray ionization time-of-flight mass spectrometry based nontargeted metabolomic analysis using rat urine. To verify the metabolic alteration at both low and high doses, reverse transcription-polymerase chain reaction (RT-PCR) and western blotting were further conducted to analyze hepatic expression of methionine adenosyltransferase Iα (Mat1a) and methionine adenosyltransferase IIα (Mat2a). Hepatic S-adenosylmethionine (SAMe) was also analyzed. A total of 199 metabolites were profiled. Statistical analysis and pathway mapping indicated that the most significant metabolic perturbations induced by BPA were the increased biotin and riboflavin excretion, increased synthesis of methylated products, elevated purine nucleotide catabolism, and increased flux through the choline metabolism pathway. We found significantly higher mRNA and protein levels of Mat1a and Mat2a, and significantly higher SAMe levels in rat liver at both low and high doses. These two genes encode critical isoenzymes that catalyze the formation of SAMe, the principal biological methyl donor involved in the choline metabolism. In conclusion, an elevated choline metabolism is underlying the mechanism of highly methylated environment and related metabolic alterations caused by BPA. The data of BPA-elevated accepted biomarkers of injury indicate that BPA induces DNA methylation damage and broad protein degradation, and the increased deleterious metabolites in choline pathway may also be involved in the toxicity of BPA.

Education and Risk of Dementia: Dose-Response Meta-Analysis of Prospective Cohort Studies.

PubMed

Xu, Wei; Tan, Lan; Wang, Hui-Fu; Tan, Meng-Shan; Tan, Lin; Li, Jie-Qiong; Zhao, Qing-Fei; Yu, Jin-Tai

2016-07-01

Educational level has been regarded as one of the most widely accepted risk factors in the epidemiological studies for dementia, despite with discordant qualitative results. However, the dose-response relation between education and incident dementia was still unknown. To quantitatively evaluate the association between exposure level to high and low education and risk of dementia, we searched PubMed, EMBASE, and the Cochrane Library up to November 2014 and references of retrieved literatures. Specific prospective cohort studies, in which educational attainment was categorized into at least three levels, were included. Newcastle-Ottawa scale was used to assess the quality of included studies. Fifteen prospective cohort studies with 55655 for low education and eight prospective cohort studies with 20172 for high education were included. In the qualitative analysis, both low and high education showed a dose-response trend with risk of dementia and Alzheimer's disease (AD). In the quantitative analysis, the dementia risk was reduced by 7 % for per year increase in education (RR, 0.93; 95 % CI, 0.92-0.94; p for overall trend = 0.000; p for nonlinearity = 0.0643). Nonetheless, we did not find statistically significant association between per year decrease in education and dementia (RR, 1.03; 95 % CI, 0.96-1.10; p for overall trend = 0.283; p for nonlinearity = 0.0041) or AD (RR, 1.03; 95 % CI, 0.97-1.10; p for overall trend = 0.357; p for nonlinearity = 0.0022). Both low and high education showed a trend of dose-response relation with risk of dementia and AD. The dementia risk was reduced by 7 % for per year increase in education.

Biological measure of compliance to Artesunate plus Amodiaquine association: interest in a Mono-Desethyl-Amodiaquine blood assay?

PubMed

Sarrassat, Sophie; Sakho, Madiagne; Le Hesran, Jean Yves

2009-04-01

The deployment of Artemisinin-based Combination Therapy for treating uncomplicated malaria poses problems in the patient compliance to these new treatments. The aim of our study was to investigate the relationship between compliance to 3 days treatment with Artesunate plus Amodiaquine (AS+AQ) and the Mono-Desethyl-Amodiaquine (MDA) blood concentration on the fourth day. A reference scale of mean MDA blood concentrations was constructed in 40 healthy adults. Each concentration corresponded to the MDA level on day 3 in a subject having one of the seven compliance degrees defined by the number and sequence of drug intakes from day 0 to day 2: one single dose on day 0, day 1 or day 2; two single doses separated by 24h, on day 0 and day 1 or on day 1 and day 2; two single doses separated by 48 h, on day 0 and day 2; three single doses, on day 0, day 1 and day 2. MDA was assayed in whole blood samples by HPLC. Non-parametric Mann and Whitney U tests were used for the comparison of two means. Our results demonstrated no clear relationship between the mean MDA blood concentrations on day 3 and compliance degrees, according to neither the number nor the sequence of doses taken. In particular, even though the differences were not significant, the mean concentration after three doses, expected to be the maximum, was unexpectedly lower than after two doses, on day 0 and day 1 or on day 1 and day 2. The high inter-individual variability of MDA concentrations attributed to the different rates of hepatic metabolism of each individual appears to have a greater effect on MDA levels than the number or timing of doses. Therefore, it seems that the role of a MDA blood assay is limited in use to discerning if none or one or more doses have been taken. A MDA assay do not allow to measure the compliance degree of one patient to AS+AQ association. Presently, interview and pill count following treatment seem to be the only tools available that may permit differentiation between degrees of compliance.

Bombesin and G-17 dose responses in duodenal ulcer and controls.

PubMed

Hirschowitz, B I; Tim, L O; Helman, C A; Molina, E

1985-11-01

Gastric acid and pepsin secretion and serum gastrin concentrations were measured in nine patients with uncomplicated duodenal ulcer (DU) and 10 normal controls in the fasting state and in response to graded doses of bombesin, a tetradecapeptide gastrin releaser, and, for reference, synthetic gastrin G-17. Serum gastrin with bombesin stimulation was significantly greater in duodenal ulcer (maximum 467 pg/ml) than in controls (153 pg/ml), while in seven of the DU group tested gastrin levels after a meal were not different from that seen in five of the normal controls. Gastric acid concentrations and outputs were greater in duodenal ulcer with both stimuli. Secretory responses were then related to serum gastrin levels; despite increasing gastrin levels with bombesin stimulation, peak outputs achieved with bombesin were only 50% of G-17 maximum in normals and up to 90% of maximum in duodenal ulcer. Up to the point of peak response to bombesin, acid and pepsin outputs were the same with exogenous and endogenous gastrin, ie, bombesin acted only via G-17. Furthermore, in direct comparison of duodenal ulcer and normals with G-17 infusion, acid and pepsin outputs related to serum gastrin were congruent up to 75% of duodenal ulcer maximum, at which point normals reached their maximum level. These data have shown that duodenal ulcer patients are not more sensitive to either exogenous or endogenous gastrin; we have also shown regulatory defects in duodenal ulcer patients not previously described: an exaggerated release of gastrin with bombesin stimulation, and a defective inhibition of acid and pepsin secretion with higher doses of bombesin.

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-E-T-13: A Feasibility Study of the Use of Hybrid Computational Phantoms for Improved Historical Dose Reconstruction in the Study of Late Radiation Effects for Hodgkin's Lymphoma

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

Petroccia, H; O'Reilly, S; Bolch, W

Purpose: Radiation-induced cancer effects are well-documented following radiotherapy. Further investigation is needed to more accurately determine a dose-response relationship for late radiation effects. Recent dosimetry studies tend to use representative patients (Taylor 2009) or anthropomorphic phantoms (Wirth 2008) for estimating organ mean doses. In this study, we compare hybrid computational phantoms to patient-specific voxel phantoms to test the accuracy of University of Florida Hybrid Phantom Library (UFHP Library) for historical dose reconstructions. Methods: A cohort of 10 patients with CT images was used to reproduce the data that was collected historically for Hodgkin's lymphoma patients (i.e. caliper measurements and photographs).more » Four types of phantoms were generated to show a range of refinement from reference hybrid-computational phantom to patient-specific phantoms. Each patient is matched to a reference phantom from the UFHP Library based on height and weight. The reference phantom is refined in the anterior/posterior direction to create a ‘caliper-scaled phantom’. A photograph is simulated using a surface rendering from segmented CT images. Further refinement in the lateral direction is performed using ratios from a simulated-photograph to create a ‘photograph and caliper-scaled phantom’; breast size and position is visually adjusted. Patient-specific hybrid phantoms, with matched organ volumes, are generated and show the capabilities of the UF Hybrid Phantom Library. Reference, caliper-scaled, photograph and caliper-scaled, and patient-specific hybrid phantoms are compared with patient-specific voxel phantoms to determine the accuracy of the study. Results: Progression from reference phantom to patient specific hybrid shows good agreement with the patient specific voxel phantoms. Each stage of refinement shows an overall trend of improvement in dose accuracy within the study, which suggests that computational phantoms can show improved accuracy in historical dose estimates. Conclusion: Computational hybrid phantoms show promise for improved accuracy within retrospective studies when CTs and other x-ray images are not available.« less

Abdominal CT with model-based iterative reconstruction (MBIR): initial results of a prospective trial comparing ultralow-dose with standard-dose imaging.

PubMed

Pickhardt, Perry J; Lubner, Meghan G; Kim, David H; Tang, Jie; Ruma, Julie A; del Rio, Alejandro Muñoz; Chen, Guang-Hong

2012-12-01

The purpose of this study was to report preliminary results of an ongoing prospective trial of ultralow-dose abdominal MDCT. Imaging with standard-dose contrast-enhanced (n = 21) and unenhanced (n = 24) clinical abdominal MDCT protocols was immediately followed by ultralow-dose imaging of a matched series of 45 consecutively registered adults (mean age, 57.9 years; mean body mass index, 28.5). The ultralow-dose images were reconstructed with filtered back projection (FBP), adaptive statistical iterative reconstruction (ASIR), and model-based iterative reconstruction (MBIR). Standard-dose series were reconstructed with FBP (reference standard). Image noise was measured at multiple predefined sites. Two blinded abdominal radiologists interpreted randomly presented ultralow-dose images for multilevel subjective image quality (5-point scale) and depiction of organ-based focal lesions. Mean dose reduction relative to the standard series was 74% (median, 78%; range, 57-88%; mean effective dose, 1.90 mSv). Mean multiorgan image noise for low-dose MBIR was 14.7 ± 2.6 HU, significantly lower than standard-dose FBP (28.9 ± 9.9 HU), low-dose FBP (59.2 ± 23.3 HU), and ASIR (45.6 ± 14.1 HU) (p < 0.001). The mean subjective image quality score for low-dose MBIR (3.0 ± 0.5) was significantly higher than for low-dose FBP (1.6 ± 0.7) and ASIR (1.8 ± 0.7) (p < 0.001). Readers identified 213 focal noncalcific lesions with standard-dose FBP. Pooled lesion detection was higher for low-dose MBIR (79.3% [169/213]) compared with low-dose FBP (66.2% [141/213]) and ASIR (62.0% [132/213]) (p < 0.05). MBIR shows great potential for substantially reducing radiation doses at routine abdominal CT. Both FBP and ASIR are limited in this regard owing to reduced image quality and diagnostic capability. Further investigation is needed to determine the optimal dose level for MBIR that maintains adequate diagnostic performance. In general, objective and subjective image quality measurements do not necessarily correlate with diagnostic performance at ultralow-dose CT.

Efficacy and safety data of subsequent entry biologics pertinent to nephrology practice: a systematic review.

PubMed

Marin, Judith Genevieve; Leung, Marianna; Lo, Clifford; Tsao, Nicole W; Martinusen, Daniel J

2014-01-01

Subsequent entry biologics (SEBs) may soon be a reality in Canadian nephrology practice. Understanding the worldwide experience with these agents will be valuable to Canadian clinicians. To compare the efficacy and safety data between SEBs used in nephrology practice and their reference biologic. Systematic review. Ovid MEDLINE, EMBASE, Cochrane Database of Systematic Reviews, Database of Abstracts of Review of Effects, Cochrane Central Register of Controlled Trials. Adult patients with chronic kidney disease (CKD). Our systematic review follows the process outlined by Cochrane Reviews. For efficacy data, all randomized controlled trials (RCTs), quasi-RCTs and observational trials in nephrology practice were included. For safety data, case series, case reports, review articles in nephrology practice and pharmacovigilance programs were included as well. Only epoetin SEBs trials were published in the literature. Ten studies involving three different epoetin SEBs (epoetin zeta, HX575 and epoetin theta) were included. The mean epoetin dose used did not differ significantly between the SEBs and the reference product. For epoetin zeta and epoetin theta, the mean hemoglobin levels achieved in the studies were similar between the SEBs and the reference epoetin. The HX 575 studies reported a mean absolute change in hemoglobin within the predefined equivalence margin, when compared with the reference biologic. In terms of safety data, 2 cases of pure-red-cell aplasia were linked to the subcutaneous administration of HX 575. Otherwise, the rate of adverse drug reactions was similar when epoetin SEBs were compared with the reference biologic. Our analysis is limited by the paucity of information available on SEB use in nephrology with the exception of epoetin SEBs. Methodological flaw was found in one of the epoetin zeta studies which accounted for 45% of pooled results. Little clinical difference was found between epoetin SEBs and the reference product. Although not deemed clinically important, the financial implication of a possible dose difference between epoetin zeta and reference product should be considered in pharmacoeconomic studies. Ongoing trials are expected to address the risk of pure-red-cell aplasia with HX 575.

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

Brent, R.L.

Many professionals are unfamiliar with radiation biology or the quantitative nature of the risks. Frequently, microwave, ultrasound, and ionizing radiation risks are confused. Although it is impossible to prove no risk for any environmental hazard, it appears that exposure to microwave radiation below the maximal permissible levels present no measurable risk to the embryo. Ultrasound exposure from diagnostic ultrasonographic imaging equipment also is quite innocuous. It is true that continued surveillance and research into potential risks of these low-level exposures should continue, but at present ultrasound not only improves obstetric care but also reduces the necessity of diagnostic x-ray procedures.more » In the field of ionizing radiation, we have as good a comprehension of the biologic effects and the quantitative maximum risks as of any other environmental hazard. Although the animal and human data support the conclusion that no increases in the incidence of gross congenital malformations, intrauterine growth retardation, or abortion will occur with exposures less than 5 rad, that does not mean that there are definitely no risks to the embryo exposed to lower doses of radiation. Whether there exists a linear or exponential dose-response relationship or a threshold exposure for genetic, carcinogenic, cell-depleting, and life-shortening effects has not been determined. In establishing maximum permissible levels for the embryo at low exposures, refer to Tables 4, 5, 6, 8, and 9. It is obvious that the risks of 1-rad or 5-rad acute exposure are far below the spontaneous risks of the developing embryo because 15 per cent of human embryos abort, 2.7 to 3.0 per cent of human embryos have major malformations, 4 per cent have intrauterine growth retardation, and 8 to 10 per cent have early- or late-onset genetic disease. 98 references.« less

Application of mathematical models to metronomic chemotherapy: What can be inferred from minimal parameterized models?

PubMed

Ledzewicz, Urszula; Schättler, Heinz

2017-08-10

Metronomic chemotherapy refers to the frequent administration of chemotherapy at relatively low, minimally toxic doses without prolonged treatment interruptions. Different from conventional or maximum-tolerated-dose chemotherapy which aims at an eradication of all malignant cells, in a metronomic dosing the goal often lies in the long-term management of the disease when eradication proves elusive. Mathematical modeling and subsequent analysis (theoretical as well as numerical) have become an increasingly more valuable tool (in silico) both for determining conditions under which specific treatment strategies should be preferred and for numerically optimizing treatment regimens. While elaborate, computationally-driven patient specific schemes that would optimize the timing and drug dose levels are still a part of the future, such procedures may become instrumental in making chemotherapy effective in situations where it currently fails. Ideally, mathematical modeling and analysis will develop into an additional decision making tool in the complicated process that is the determination of efficient chemotherapy regimens. In this article, we review some of the results that have been obtained about metronomic chemotherapy from mathematical models and what they infer about the structure of optimal treatment regimens. Copyright © 2017 Elsevier B.V. All rights reserved.

Fluence-to-dose conversion coefficients for heavy ions calculated using the PHITS code and the ICRP/ICRU adult reference computational phantoms.

PubMed

Sato, Tatsuhiko; Endo, Akira; Niita, Koji

2010-04-21

The fluence to organ-absorbed-dose and effective-dose conversion coefficients for heavy ions with atomic numbers up to 28 and energies from 1 MeV/nucleon to 100 GeV/nucleon were calculated using the PHITS code coupled to the ICRP/ICRU adult reference computational phantoms, following the instruction given in ICRP Publication 103 (2007 (Oxford: Pergamon)). The conversion coefficients for effective dose equivalents derived using the radiation quality factors of both Q(L) and Q(y) relationships were also estimated, utilizing the functions for calculating the probability densities of absorbed dose in terms of LET (L) and lineal energy (y), respectively, implemented in PHITS. The calculation results indicate that the effective dose can generally give a conservative estimation of the effective dose equivalent for heavy-ion exposure, although it is occasionally too conservative especially for high-energy lighter-ion irradiations. It is also found from the calculation that the conversion coefficients for the Q(y)-based effective dose equivalents are generally smaller than the corresponding Q(L)-based values because of the conceptual difference between LET and y as well as the numerical incompatibility between the Q(L) and Q(y) relationships. The calculated data of these dose conversion coefficients are very useful for the dose estimation of astronauts due to cosmic-ray exposure.

Patient doses and occupational exposure in a hybrid operating room.

PubMed

Andrés, C; Pérez-García, H; Agulla, M; Torres, R; Miguel, D; Del Castillo, A; Flota, C M; Alonso, D; de Frutos, J; Vaquero, C

2017-05-01

This study aimed to characterize the radiation exposure to patients and workers in a new vascular hybrid operating room during X-ray-guided procedures. During one year, data from 260 interventions performed in a hybrid operating room equipped with a Siemens Artis Zeego angiography system were monitored. The patient doses were analysed using the following parameters: radiation time, kerma-area product, patient entrance reference point dose and peak skin dose. Staff radiation exposure and ambient dose equivalent were also measured using direct reading dosimeters and thermoluminescent dosimeters. The radiation time, kerma-area product, patient entrance reference point dose and peak skin dose were, on average, 19:15min, 67Gy·cm 2 , 0.41Gy and 0.23Gy, respectively. Although the contribution of the acquisition mode was smaller than 5% in terms of the radiation time, this mode accounted for more than 60% of the effective dose per patient. All of the worker dose measurements remained below the limits established by law. The working conditions in the hybrid operating room HOR are safe in terms of patient and staff radiation protection. Nevertheless, doses are highly dependent on the workload; thus, further research is necessary to evaluate any possible radiological deviation of the daily working conditions in the HOR. Copyright © 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

Hemolytic Potential of Tafenoquine in Female Volunteers Heterozygous for Glucose-6-Phosphate Dehydrogenase (G6PD) Deficiency (G6PD Mahidol Variant) versus G6PD-Normal Volunteers

PubMed Central

Rueangweerayut, Ronnatrai; Bancone, Germana; Harrell, Emma J.; Beelen, Andrew P.; Kongpatanakul, Supornchai; Möhrle, Jörg J.; Rousell, Vicki; Mohamed, Khadeeja; Qureshi, Ammar; Narayan, Sushma; Yubon, Nushara; Miller, Ann; Nosten, François H.; Luzzatto, Lucio; Duparc, Stephan; Kleim, Jörg-Peter; Green, Justin A.

2017-01-01

Abstract. Tafenoquine is an 8-aminoquinoline under investigation for the prevention of relapse in Plasmodium vivax malaria. This open-label, dose-escalation study assessed quantitatively the hemolytic risk with tafenoquine in female healthy volunteers heterozygous for the Mahidol487A glucose-6-phosphate dehydrogenase (G6PD)-deficient variant versus G6PD-normal females, and with reference to primaquine. Six G6PD-heterozygous subjects (G6PD enzyme activity 40–60% of normal) and six G6PD-normal subjects per treatment group received single-dose tafenoquine (100, 200, or 300 mg) or primaquine (15 mg × 14 days). All participants had pretreatment hemoglobin levels ≥ 12.0 g/dL. Tafenoquine dose escalation stopped when hemoglobin decreased by ≥ 2.5 g/dL (or hematocrit decline ≥ 7.5%) versus pretreatment values in ≥ 3/6 subjects. A dose–response was evident in G6PD-heterozygous subjects (N = 15) receiving tafenoquine for the maximum decrease in hemoglobin versus pretreatment values. Hemoglobin declines were similar for tafenoquine 300 mg (−2.65 to −2.95 g/dL [N = 3]) and primaquine (−1.25 to −3.0 g/dL [N = 5]). Two further cohorts of G6PD-heterozygous subjects with G6PD enzyme levels 61–80% (N = 2) and > 80% (N = 5) of the site median normal received tafenoquine 200 mg; hemolysis was less pronounced at higher G6PD enzyme activities. Tafenoquine hemolytic potential was dose dependent, and hemolysis was greater in G6PD-heterozygous females with lower G6PD enzyme activity levels. Single-dose tafenoquine 300 mg did not appear to increase the severity of hemolysis versus primaquine 15 mg × 14 days. PMID:28749773

Prescribing smoked cannabis for chronic noncancer pain: preliminary recommendations.

PubMed

Kahan, Meldon; Srivastava, Anita; Spithoff, Sheryl; Bromley, Lisa

2014-12-01

To offer preliminary guidance on prescribing smoked cannabis for chronic pain before the release of formal guidelines. We reviewed the literature on the analgesic effectiveness of smoked cannabis and the harms of medical and recreational cannabis use. We developed recommendations on indications, contraindications, precautions, and dosing of smoked cannabis, and categorized the recommendations based on levels of evidence. Evidence is mostly level II (well conducted observational studies) and III (expert opinion). Smoked cannabis might be indicated for patients with severe neuropathic pain conditions who have not responded to adequate trials of pharmaceutical cannabinoids and standard analgesics (level II evidence). Smoked cannabis is contraindicated in patients who are 25 years of age or younger (level II evidence); who have a current, past, or strong family history of psychosis (level II evidence); who have a current or past cannabis use disorder (level III evidence); who have a current substance use disorder (level III evidence); who have cardiovascular or respiratory disease (level III evidence); or who are pregnant or planning to become pregnant (level II evidence). It should be used with caution in patients who smoke tobacco (level II evidence), who are at increased risk of cardiovascular disease (level III evidence), who have anxiety or mood disorders (level II evidence), or who are taking higher doses of opioids or benzodiazepines (level III evidence). Cannabis users should be advised not to drive for at least 3 to 4 hours after smoking, for at least 6 hours after oral ingestion, and for at least 8 hours if they experience a subjective "high" (level II evidence). The maximum recommended dose is 1 inhalation 4 times per day (approximately 400 mg per day) of dried cannabis containing 9% delta-9-tetrahydrocannabinol (level III evidence). Physicians should avoid referring patients to "cannabinoid" clinics (level III evidence). Future guidelines should be based on systematic review of the literature on the safety and effectiveness of smoked cannabis. Further research is needed on the effectiveness and long-term safety of smoked cannabis compared with pharmaceutical cannabinoids, opioids, and other standard analgesics. Copyright© the College of Family Physicians of Canada.

Prescribing smoked cannabis for chronic noncancer pain

PubMed Central

Kahan, Meldon; Srivastava, Anita; Spithoff, Sheryl; Bromley, Lisa

2014-01-01

Objective To offer preliminary guidance on prescribing smoked cannabis for chronic pain before the release of formal guidelines. Quality of evidence We reviewed the literature on the analgesic effectiveness of smoked cannabis and the harms of medical and recreational cannabis use. We developed recommendations on indications, contraindications, precautions, and dosing of smoked cannabis, and categorized the recommendations based on levels of evidence. Evidence is mostly level II (well conducted observational studies) and III (expert opinion). Main message Smoked cannabis might be indicated for patients with severe neuropathic pain conditions who have not responded to adequate trials of pharmaceutical cannabinoids and standard analgesics (level II evidence). Smoked cannabis is contraindicated in patients who are 25 years of age or younger (level II evidence); who have a current, past, or strong family history of psychosis (level II evidence); who have a current or past cannabis use disorder (level III evidence); who have a current substance use disorder (level III evidence); who have cardiovascular or respiratory disease (level III evidence); or who are pregnant or planning to become pregnant (level II evidence). It should be used with caution in patients who smoke tobacco (level II evidence), who are at increased risk of cardiovascular disease (level III evidence), who have anxiety or mood disorders (level II evidence), or who are taking higher doses of opioids or benzodiazepines (level III evidence). Cannabis users should be advised not to drive for at least 3 to 4 hours after smoking, for at least 6 hours after oral ingestion, and for at least 8 hours if they experience a subjective “high” (level II evidence). The maximum recommended dose is 1 inhalation 4 times per day (approximately 400 mg per day) of dried cannabis containing 9% delta-9-tetrahydrocannabinol (level III evidence). Physicians should avoid referring patients to “cannabinoid” clinics (level III evidence). Conclusion Future guidelines should be based on systematic review of the literature on the safety and effectiveness of smoked cannabis. Further research is needed on the effectiveness and long-term safety of smoked cannabis compared with pharmaceutical cannabinoids, opioids, and other standard analgesics. PMID:25500598

Graph theoretical analysis, insilico modeling, design, and synthesis of compounds containing benzimidazole skeleton as antidepressant agents.

PubMed

Theivendren, Panneerselvam; Subramanian, Arumugam; Murugan, Indhumathy; Joshi, Shrinivas D; More, Uttam A

2017-05-01

In this study, drug target was identified using KEGG database and network analysis through Cytoscape software. Designed series of novel benzimidazoles were taken along with reference standard Flibanserin for insilico modeling. The novel 4-(1H-benzo[d]imidazol-2-yl)-N-(substituted phenyl)-4-oxobutanamide (3a-j) analogs were synthesized and evaluated for their antidepressant activity. Reaction of 4-(1H-benzo[d]imidazol-2-yl)-4-oxobutanoic acid (1) with 4-(1H-benzo [d] imidazol-2-yl)-4-oxobutanoyl chloride (2) furnished novel 4-(1H-benzo [d] imidazol-2-yl)-N-(substituted phenyl)-4-oxobutanamide (3a-j). All the newly synthesized compounds were characterized by IR, 1 H-NMR, and mass spectral analysis. The antidepressant activities of synthesized derivatives were compared with standard drug clomipramine at a dose level of 20 mg/kg. Among the derivatives tested, most of the compounds were found to have potent activity against depression. The high level of activity was shown by the compounds 3d, 3e, 3i, and it significantly reduced the duration of immobility time at the dose level of 50 mg/kg. © 2016 John Wiley & Sons A/S.

Definitions and outlook targeting x-ray exposure of patients in diagnostic imaging

NASA Astrophysics Data System (ADS)

Regulla, Dieter F.

2011-03-01

Computer tomography (CT) is vital and currently irreplaceable in diagnostic radiology. But CT operates with ionizing radiation which may cause cancer or non-cancer diseases in humans. The degree of radiation impact depends on the dose administered by an investigation. And this is the core issue: Even CT exams executed lege artis, administer doses to patients which by magnitude are far beyond the level of hitherto known doses of conventional film-screen techniques. Patients undergoing one or multiple CT examinations, digital angiographies or interventions will be exposed to effective doses between roughly several mSv and several 100 mSv depending on type and frequency of the diagnostic investigations. From the radiation protection point of view, there is therefore the worldwide problem of formulating firm rules for the control of these high-dose investigations, as dose limits can not be established for reasons of the medical benefit. This makes the difference compared with radiation protection for occupationally exposed persons. What remains is "software", namely "justification" and "optimization". Justification requires balancing the interests between the health benefit and the potential harm of an exam which has to be responsibly executed by the physician himself; therefore the radiologists' associations are in the duty to prepare practicable rules for justification. Optimization again needs a cooperative solution, and that is the establishment of reference doses for diagnostic examinations, to be checked by the technical service of the producers' companies. Experts and authorities have been aware of the high-dose dilemma in diagnostic imaging since long. It is time for the reflection of active solutions and their implementation into practice.

Does Intensity Matter? Preschoolers' Print Knowledge Development within a Classroom-Based Intervention

ERIC Educational Resources Information Center

McGinty, Anita S.; Breit-Smith, Allison; Fan, Xitao; Justice, Laura M.; Kaderavek, Joan N.

2011-01-01

The present study examined the extent to which two dimensions of intervention intensity, ("dose frequency" and "dose") of a 30-week print-referencing intervention related to the print knowledge development of 367 randomly selected children from 55 preschool classrooms. "Dose frequency" refers to the number of intervention sessions implemented per…

10 CFR 20.1003 - Definitions.

Code of Federal Regulations, 2014 CFR

2014-01-01

... assessment of dose equivalent by the use of devices designed to be worn by an individual; (2) The assessment... equipment) means devices designed to be worn by a single individual for the assessment of dose equivalent... radionuclide in a year by the reference man that would result in a committed effective dose equivalent of 5...

10 CFR 20.1003 - Definitions.

Code of Federal Regulations, 2012 CFR

2012-01-01

... assessment of dose equivalent by the use of devices designed to be worn by an individual; (2) The assessment... equipment) means devices designed to be worn by a single individual for the assessment of dose equivalent... radionuclide in a year by the reference man that would result in a committed effective dose equivalent of 5...

10 CFR 20.1003 - Definitions.

Code of Federal Regulations, 2011 CFR

2011-01-01

... assessment of dose equivalent by the use of devices designed to be worn by an individual; (2) The assessment... equipment) means devices designed to be worn by a single individual for the assessment of dose equivalent... radionuclide in a year by the reference man that would result in a committed effective dose equivalent of 5...

10 CFR 20.1003 - Definitions.

Code of Federal Regulations, 2013 CFR

2013-01-01

... assessment of dose equivalent by the use of devices designed to be worn by an individual; (2) The assessment... equipment) means devices designed to be worn by a single individual for the assessment of dose equivalent... radionuclide in a year by the reference man that would result in a committed effective dose equivalent of 5...

10 CFR 20.1003 - Definitions.

Code of Federal Regulations, 2010 CFR

2010-01-01

... assessment of dose equivalent by the use of devices designed to be worn by an individual; (2) The assessment... equipment) means devices designed to be worn by a single individual for the assessment of dose equivalent... radionuclide in a year by the reference man that would result in a committed effective dose equivalent of 5...

[STUDYING SOME PHARMACOLOGICAL EFFECTS OF NEW 3-HYDROXYPYRIDINE DERIVATIVE].

PubMed

Yasnetsov, V V; Tsublova, E G; Yasnetsov, Vic V; Skachilova, S Ya; Karsanova, S K; Ivanov, Yu V

2016-01-01

It was established that a new 3-hydroxypyridine (3-HP) derivative, 2-ethyl-6-methyl-3-hydroxypyridine L-aspartate (3-HP), in small doses (1 and 5 mg/kg) increased physical performance in treadmill and swimming tests on rats. The new substance showed greater or equal effects compared to the reference actoprotector drugs metaprot and ladasten in much higher doses. The gluconeogenesis inhibitor tryptophan significantly (74 ± 5%, p < 0.01) prevented this stimulatory effect of 3-HPA in the treadmill test on rats. 3-HPA at a higher dose (30 mg/kg) had marked antiamnesic effect on various models of amnesia in mice. It was more effective than reference drugs mexidol (another 3-HP derivative) in a dose of 30 mg/kg and nootropic drug piracetam in a dose of 200 mg/kg, but had equal effect with these drugs in doses of 50 and 800 mg/kg, respectively. 3-HPA (30 mg/kg per day) had neuroprotective effect in rats with brain ischemia and decreased the neurologic deficiency more effectively than mexidol (50 mg/kg per day).

Derivation of a reference dose for a complex petroleum hydrocarbon mixture

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

Ryer-Powder, J.E.; LaPirre, A.; Scofield, R.

1997-12-31

Petroleum hydrocarbon mixtures pose a challenge in assessing potential health effects associated with environmental exposures through impacted media. Two components of risk assessment that must be addressed when evaluating these mixtures are toxicity and environmental fate. In this paper, we focus on issues regarding toxicity. Specifically, we have developed a methodology to derive a reference dose (RfD) for a complex petroleum hydrocarbon mixture referred to as diluent. Diluent is a solvent used in the production of crude oil and is composed of hydrocarbons in the middle distillate range. Two conservative approaches to developing a reference dose for diluent are presented.more » Both involve separating the diluent into carbon number ranges (e.g., diluent consists of hydrocarbons containing between 5 carbons and greater than 21 carbons, so, the mixture can be divided into mixtures of hydrocarbons having 5 carbons, 6-11 carbons, etcetera) and assigning each range a representative RfD. In the first approach, the representative RfD for each range is that of one specific chemical within the range (e.g., the reference dose for the C{sub 5}-C{sub 8} carbon range is that of n-hexane). In the second approach, the RfD dose for each range is that of a mixture of chemicals representative of each carbon number range (e.g., the RfD for the C{sub 6} to C{sub 11} carbon range is that of mineral spirits). The RfD for each carbon range is then multiplied by the percent of diluent in the corresponding range and the products are added to arrive at a final RfD. The RfD for diluent using the first approach is estimated at 2 mg/kg-day and that using the second approach is estimated at 1 mg/kg-day.« less

Percentiles of the product of uncertainty factors for establishing probabilistic reference doses.

PubMed

Gaylor, D W; Kodell, R L

2000-04-01

Exposure guidelines for potentially toxic substances are often based on a reference dose (RfD) that is determined by dividing a no-observed-adverse-effect-level (NOAEL), lowest-observed-adverse-effect-level (LOAEL), or benchmark dose (BD) corresponding to a low level of risk, by a product of uncertainty factors. The uncertainty factors for animal to human extrapolation, variable sensitivities among humans, extrapolation from measured subchronic effects to unknown results for chronic exposures, and extrapolation from a LOAEL to a NOAEL can be thought of as random variables that vary from chemical to chemical. Selected databases are examined that provide distributions across chemicals of inter- and intraspecies effects, ratios of LOAELs to NOAELs, and differences in acute and chronic effects, to illustrate the determination of percentiles for uncertainty factors. The distributions of uncertainty factors tend to be approximately lognormally distributed. The logarithm of the product of independent uncertainty factors is approximately distributed as the sum of normally distributed variables, making it possible to estimate percentiles for the product. Hence, the size of the products of uncertainty factors can be selected to provide adequate safety for a large percentage (e.g., approximately 95%) of RfDs. For the databases used to describe the distributions of uncertainty factors, using values of 10 appear to be reasonable and conservative. For the databases examined the following simple "Rule of 3s" is suggested that exceeds the estimated 95th percentile of the product of uncertainty factors: If only a single uncertainty factor is required use 33, for any two uncertainty factors use 3 x 33 approximately 100, for any three uncertainty factors use a combined factor of 3 x 100 = 300, and if all four uncertainty factors are needed use a total factor of 3 x 300 = 900. If near the 99th percentile is desired use another factor of 3. An additional factor may be needed for inadequate data or a modifying factor for other uncertainties (e.g., different routes of exposure) not covered above.

Radiation Protection in Pediatric Radiology: Results of a Survey Among Dutch Hospitals.

PubMed

Bijwaard, Harmen; Valk, Doreth; de Waard-Schalkx, Ischa

2016-10-01

A survey about radiation protection in pediatric radiology was conducted among 22 general and seven children's hospitals in the Netherlands. Questions concerned, for example, child protocols used for CT, fluoroscopy and x-ray imaging, number of images and scans made, radiation doses and measures taken to reduce these, special tools used for children, and quality assurance issues. The answers received from 27 hospitals indicate that radiation protection practices differ considerably between general and children's hospitals but also between the respective general and children's hospitals. It is recommended that hospitals consult each other to come up with more uniform best practices. Few hospitals were able to supply doses that can be compared to the national Diagnostic Reference Levels (DRLs). The ones that could be compared exceeded the DRLs in one in five cases, which is more than was expected beforehand.

Fluence-to-dose conversion coefficients for neutrons and protons calculated using the PHITS code and ICRP/ICRU adult reference computational phantoms.

PubMed

Sato, Tatsuhiko; Endo, Akira; Zankl, Maria; Petoussi-Henss, Nina; Niita, Koji

2009-04-07

The fluence to organ-dose and effective-dose conversion coefficients for neutrons and protons with energies up to 100 GeV was calculated using the PHITS code coupled to male and female adult reference computational phantoms, which are to be released as a common ICRP/ICRU publication. For the calculation, the radiation and tissue weighting factors, w(R) and w(T), respectively, as revised in ICRP Publication 103 were employed. The conversion coefficients for effective dose equivalents derived using the radiation quality factors of both Q(L) and Q(y) relationships were also estimated, utilizing the functions for calculating the probability densities of the absorbed dose in terms of LET (L) and lineal energy (y), respectively, implemented in PHITS. By comparing these data with the corresponding data for the effective dose, we found that the numerical compatibilities of the revised w(R) with the Q(L) and Q(y) relationships are fairly established. The calculated data of these dose conversion coefficients are indispensable for constructing the radiation protection systems based on the new recommendations given in ICRP103 for aircrews and astronauts, as well as for workers in accelerators and nuclear facilities.

A revision of the gamma-evaluation concept for the comparison of dose distributions.

PubMed

Bakai, Annemarie; Alber, Markus; Nüsslin, Fridtjof

2003-11-07

A method for the quantitative four-dimensional (4D) evaluation of discrete dose data based on gradient-dependent local acceptance thresholds is presented. The method takes into account the local dose gradients of a reference distribution for critical appraisal of misalignment and collimation errors. These contribute to the maximum tolerable dose error at each evaluation point to which the local dose differences between comparison and reference data are compared. As shown, the presented concept is analogous to the gamma-concept of Low et al (1998a Med. Phys. 25 656-61) if extended to (3+1) dimensions. The pointwise dose comparisons of the reformulated concept are easier to perform and speed up the evaluation process considerably, especially for fine-grid evaluations of 3D dose distributions. The occurrences of false negative indications due to the discrete nature of the data are reduced with the method. The presented method was applied to film-measured, clinical data and compared with gamma-evaluations. 4D and 3D evaluations were performed. Comparisons prove that 4D evaluations have to be given priority, especially if complex treatment situations are verified, e.g., non-coplanar beam configurations.

SU-F-P-19: Fetal Dose Estimate for a High-Dose Fluoroscopy Guided Intervention Using Modern Data Tools

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

Moirano, J

Purpose: An accurate dose estimate is necessary for effective patient management after a fetal exposure. In the case of a high-dose exposure, it is critical to use all resources available in order to make the most accurate assessment of the fetal dose. This work will demonstrate a methodology for accurate fetal dose estimation using tools that have recently become available in many clinics, and show examples of best practices for collecting data and performing the fetal dose calculation. Methods: A fetal dose estimate calculation was performed using modern data collection tools to determine parameters for the calculation. The reference pointmore » air kerma as displayed by the fluoroscopic system was checked for accuracy. A cumulative dose incidence map and DICOM header mining were used to determine the displayed reference point air kerma. Corrections for attenuation caused by the patient table and pad were measured and applied in order to determine the peak skin dose. The position and depth of the fetus was determined by ultrasound imaging and consultation with a radiologist. The data collected was used to determine a normalized uterus dose from Monte Carlo simulation data. Fetal dose values from this process were compared to other accepted calculation methods. Results: An accurate high-dose fetal dose estimate was made. Comparison to accepted legacy methods were were within 35% of estimated values. Conclusion: Modern data collection and reporting methods ease the process for estimation of fetal dose from interventional fluoroscopy exposures. Many aspects of the calculation can now be quantified rather than estimated, which should allow for a more accurate estimation of fetal dose.« less

SU-F-BRD-15: Quality Correction Factors in Scanned Or Broad Proton Therapy Beams Are Indistinguishable

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

Sorriaux, J; Lee, J; ICTEAM Institute, Universite catholique de Louvain, Louvain-la-Neuve

2015-06-15

Purpose: The IAEA TRS-398 code of practice details the reference conditions for reference dosimetry of proton beams using ionization chambers and the required beam quality correction factors (kQ). Pencil beam scanning (PBS) requires multiple spots to reproduce the reference conditions. The objective is to demonstrate, using Monte Carlo (MC) calculations, that kQ factors for broad beams can be used for scanned beams under the same reference conditions with no significant additional uncertainty. We consider hereafter the general Alfonso formalism (Alfonso et al, 2008) for non-standard beam. Methods: To approach the reference conditions and the associated dose distributions, PBS must combinemore » many pencil beams with range modulation and shaping techniques different than those used in passive systems (broad beams). This might lead to a different energy spectrum at the measurement point. In order to evaluate the impact of these differences on kQ factors, ion chamber responses are computed with MC (Geant4 9.6) in a dedicated scanned pencil beam (Q-pcsr) producing a 10×10cm2 composite field with a flat dose distribution from 10 to 16 cm depth. Ion chamber responses are also computed by MC in a broad beam with quality Q-ds (double scattering). The dose distribution of Q -pcsr matches the dose distribution of Q-ds. k-(Q-pcsr,Q-ds) is computed for a 2×2×0.2cm{sup 3} idealized air cavity and a realistic plane-parallel ion chamber (IC). Results: Under reference conditions, quality correction factors for a scanned composite field versus a broad beam are the same for air cavity dose response, k-(Q-pcsr,Q-ds) =1.001±0.001 and for a Roos IC, k-(Q-pcsr,Q-ds) =0.999±0.005. Conclusion: Quality correction factors for ion chamber response in scanned and broad proton therapy beams are identical under reference conditions within the calculation uncertainties. The results indicate that quality correction factors published in IAEA TRS-398 can be used for scanned beams in the SOBP of a high-energy proton beam. Jefferson Sorriaux is financed by the Walloon Region under the convention 1217662. Jefferson Sorriaux is sponsored by a public-private partnership IBA - Walloon Region.« less

Curative potential of GM-CSF-secreting tumor cell vaccines on established orthotopic liver tumors: mechanisms for the superior antitumor activity of live tumor cell vaccines.

PubMed

Tai, Kuo-Feng; Chen, Ding-Shinn; Hwang, Lih-Hwa

2004-01-01

In preclinical studies, tumor cells genetically engineered to secrete cytokines, hereafter referred to as tumor cell vaccines, can often generate systemic antitumor immunity. This study investigated the therapeutic effects of live or irradiated tumor cell vaccines that secrete granulocyte-macrophage colony-stimulating factor (GM-CSF) on established orthotopic liver tumors. Experimental results indicated that two doses (3 x 10(7) cells per dose) of irradiated tumor cell vaccines were therapeutically ineffective, whereas one dose (3 x 10(6) cells) of live tumor cell vaccines caused complete tumor regression. In vivo depletion of CD8+ T cells, but not natural killer cells, restored tumor formation in the live vaccine-treated animals. Additionally, the treatment of cells with live vaccine induced markedly higher levels of cytotoxic T lymphocyte activity than the irradiated vaccines in the draining lymph nodes. The higher levels of cytokine and antigen loads could partly explain the superior antitumor activity of live tumor cell vaccines, but other unidentified mechanisms could also play a role in the early T cell activation in the lymph nodes. A protocol using multiple and higher dosages of irradiated tumor cell vaccines also caused significant regression of liver tumors. These results suggest that the GM-CSF-secreting tumor cell vaccines are highly promising for orthotopic liver tumors if higher levels of immune responses are elicited during early tumor development. Copyright 2004 National Science Council, ROC and S. Karger AG, Basel

Toxicity reference values for chlorophacinone and their application for assessing anticoagulant rodenticide risk to raptors.

PubMed

Rattner, Barnett A; Horak, Katherine E; Lazarus, Rebecca S; Schultz, Sandra L; Knowles, Susan; Abbo, Benjamin G; Volker, Steven F

2015-05-01

Despite widespread use and benefit, there are growing concerns regarding hazards of second-generation anticoagulant rodenticides to non-target wildlife which may result in expanded use of first-generation compounds, including chlorophacinone (CPN). The toxicity of CPN over a 7-day exposure period was investigated in American kestrels (Falco sparverius) fed either rat tissue mechanically-amended with CPN, tissue from rats fed Rozol(®) bait (biologically-incorporated CPN), or control diets (tissue from untreated rats or commercial bird of prey diet) ad libitum. Nominal CPN concentrations in the formulated diets were 0.15, 0.75 and 1.5 µg/g food wet weight, and measured concentrations averaged 94 % of target values. Kestrel food consumption was similar among groups and body weight varied by less than 6 %. Overt signs of intoxication, liver CPN residues, and changes in prothrombin time (PT), Russell's viper venom time (RVVT) and hematocrit, were generally dose-dependent. Histological evidence of hemorrhage was present at all CPN dose levels, and most frequently observed in pectoral muscle and heart. There were no apparent differences in toxicity between mechanically-amended and biologically-incorporated CPN diet formulations. Dietary-based toxicity reference values at which clotting times were prolonged in 50 % of the kestrels were 79.2 µg CPN consumed/kg body weight-day for PT and 39.1 µg/kg body weight-day for RVVT. Based upon daily food consumption of kestrels and previously reported CPN concentrations found in small mammals following field baiting trials, these toxicity reference values might be exceeded by free-ranging raptors consuming such exposed prey. Tissue-based toxicity reference values for coagulopathy in 50 % of exposed birds were 0.107 µg CPN/g liver wet weight for PT and 0.076 µg/g liver for RVVT, and are below the range of residue levels reported in raptor mortality incidents attributed to CPN exposure. Sublethal responses associated with exposure to environmentally realistic concentrations of CPN could compromise survival of free-ranging raptors, and should be considered in weighing the costs and benefits of anticoagulant rodenticide use in pest control and eradication programs.

Methods for Derivation of Inhalation Reference Concentrations and Application of Inhalation Dosimetry

EPA Pesticide Factsheets

EPA's methodology for estimation of inhalation reference concentrations (RfCs) as benchmark estimates of the quantitative dose-response assessment of chronic noncancer toxicity for individual inhaled chemicals.

Vanderbilt University Gamma Irradiation of Nano-modified Concrete (2017 Milestone Report)

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

Deichert, Geoffrey G.; Linton, Kory D.; Terrani, Kurt A.

This document outlines the irradiation of concrete specimens in the Gamma Irradiation Facility in the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory (ORNL). Two gamma irradiation runs were performed in July of 2017 on 18 reference mortar bar specimens, 26 reference cement paste bar specimens, and 28 reference cement paste tab specimens to determine the dose and temperature response of the specimens in the gamma irradiation environment. Specimens from the first two gamma irradiations were surveyed and released to Vanderbilt University. The temperature and dose information obtained informs the test parameters of the final two gamma irradiationsmore » of nano-modified concrete planned for FY 2018.« less

Safety assessment and single-dose toxicokinetics of the flavouring agent myricitrin in Sprague-Dawley rats.

PubMed

Maronpot, Robert R; Koyanagi, Mihoko; Davis, Jeffrey; Recio, Leslie; Marbury, Dean; Boyle, Molly; Hayashi, Shim-mo

2015-01-01

Myricitrin, a flavonol rhamnoside of myricetin extracted from the Chinese bayberry (Myrica rubra Siebold) plant, has been used in Japan since 1992 as a flavour modifier in snack foods, dairy products, and beverages. It is affirmed as generally recognised as safe (GRAS) by the US Flavour and Extract Manufacturer Association (FEMA) and is considered safe by the Joint FAO/WHO Expert Committee on Food Additives (JECFA) at current estimated dietary exposures. In anticipation of expanded marketing, 97% pure myricitrin was fed to male and female Sprague-Dawley rats at dietary concentrations of 0.5%, 1.5% and 5.0% in a 90-day toxicity study. There was increased food consumption and decreased body weight gain in males exposed to 5% myricitrin. Blood values were within laboratory reference ranges except for mean increases in basophils in low- and high-dose males and serum phosphorus in high-dose males. In the absence of abnormal clinical or histopathological changes, these changes are not considered adverse. Based on the 90-day rat toxicity study, the no observed adverse effect level (NOAEL) is 2926 mg kg(-1) day(-1) in males and 3197 mg kg(-1) day(-1) in females. Gavage administration of myricitrin resulted in blood levels of myricitrin within 1 h after single oral doses of 250, 500 or 1000 mg kg(-1) body weight, indicating direct absorption of the glycosylated form of this flavonoid. Blood levels of myricetin, a metabolite of myricitrin, were not present in rats dosed orally with 1.6 mg kg(-1) myricetin, but were present only at 12 or 24 h in one of five, in three of five, and in four of five rats dosed with 250, 500 and 1000 mg myricitrin kg(-1) body weight, respectively, possibly a result of hepatic conversion of myricitrin to myricetin and enterohepatic recirculation of the resulting myricetin. The current studies further support prior safety assessments of myricitrin as a food flavouring.

A Unified Probabilistic Framework for Dose-Response Assessment of Human Health Effects.

PubMed

Chiu, Weihsueh A; Slob, Wout

2015-12-01

When chemical health hazards have been identified, probabilistic dose-response assessment ("hazard characterization") quantifies uncertainty and/or variability in toxicity as a function of human exposure. Existing probabilistic approaches differ for different types of endpoints or modes-of-action, lacking a unifying framework. We developed a unified framework for probabilistic dose-response assessment. We established a framework based on four principles: a) individual and population dose responses are distinct; b) dose-response relationships for all (including quantal) endpoints can be recast as relating to an underlying continuous measure of response at the individual level; c) for effects relevant to humans, "effect metrics" can be specified to define "toxicologically equivalent" sizes for this underlying individual response; and d) dose-response assessment requires making adjustments and accounting for uncertainty and variability. We then derived a step-by-step probabilistic approach for dose-response assessment of animal toxicology data similar to how nonprobabilistic reference doses are derived, illustrating the approach with example non-cancer and cancer datasets. Probabilistically derived exposure limits are based on estimating a "target human dose" (HDMI), which requires risk management-informed choices for the magnitude (M) of individual effect being protected against, the remaining incidence (I) of individuals with effects ≥ M in the population, and the percent confidence. In the example datasets, probabilistically derived 90% confidence intervals for HDMI values span a 40- to 60-fold range, where I = 1% of the population experiences ≥ M = 1%-10% effect sizes. Although some implementation challenges remain, this unified probabilistic framework can provide substantially more complete and transparent characterization of chemical hazards and support better-informed risk management decisions.

Effects of dosage, comorbidities, and food on isoniazid pharmacokinetics in Peruvian tuberculosis patients.

PubMed

Requena-Méndez, Ana; Davies, Geraint; Waterhouse, David; Ardrey, Alison; Jave, Oswaldo; López-Romero, Sonia Llanet; Ward, Stephen A; Moore, David A J

2014-12-01

Poor response to tuberculosis (TB) therapy might be attributable to subtherapeutic levels in drug-compliant patients. Pharmacokinetic (PK) parameters can be affected by several factors, such as comorbidities or the interaction of TB drugs with food. This study aimed to determine the PK of isoniazid (INH) in a Peruvian TB population under observed daily and twice-weekly (i.e., biweekly) therapy. Isoniazid levels were analyzed at 2 and 6 h after drug intake using liquid chromatography mass spectrometric methods. A total of 107 recruited patients had available PK data; of these 107 patients, 42.1% received biweekly isoniazid. The mean biweekly dose (12.8 mg/kg of body weight/day) was significantly lower than the nominal dose of 15 mg/kg/day (P < 0.001), and this effect was particularly marked in patients with concurrent diabetes and in males. The median maximum plasma concentration (Cmax) and area under the concentration-time curve from 0 to 6 h (AUC0-6) were 2.77 mg/liter and 9.71 mg · h/liter, respectively, for daily administration and 8.74 mg/liter and 37.8 mg · h/liter, respectively, for biweekly administration. There were no differences in the Cmax with respect to gender, diabetes mellitus (DM) status, or HIV status. Food was weakly associated with lower levels of isoniazid during the continuation phase. Overall, 34% of patients during the intensive phase and 33.3% during the continuation phase did not reach the Cmax reference value. However, low levels of INH were not associated with poorer clinical outcomes. In our population, INH exposure was affected by weight-adjusted dose and by food, but comorbidities did not indicate any effect on PK. We were unable to demonstrate a clear relationship between the Cmax and treatment outcome in this data set. Twice-weekly weight-adjusted dosing of INH appears to be quite robust with respect to important potentially influential patient factors under program conditions. Copyright © 2014 Requena-Méndez et al.

Dosimetry for Small Fields in Stereotactic Radiosurgery Using Gafchromic MD-V2-55 Film, TLD-100 and Alanine Dosimeters

PubMed Central

Massillon-JL, Guerda; Cueva-Prócel, Diego; Díaz-Aguirre, Porfirio; Rodríguez-Ponce, Miguel; Herrera-Martínez, Flor

2013-01-01

This work investigated the suitability of passive dosimeters for reference dosimetry in small fields with acceptable accuracy. Absorbed dose to water rate was determined in nine small radiation fields with diameters between 4 and 35 mm in a Leksell Gamma Knife (LGK) and a modified linear accelerator (linac) for stereotactic radiosurgery treatments. Measurements were made using Gafchromic film (MD-V2-55), alanine and thermoluminescent (TLD-100) dosimeters and compared with conventional dosimetry systems. Detectors were calibrated in terms of absorbed dose to water in 60Co gamma-ray and 6 MV x-ray reference (10×10 cm2) fields using an ionization chamber calibrated at a standards laboratory. Absorbed dose to water rate computed with MD-V2-55 was higher than that obtained with the others dosimeters, possibly due to a smaller volume averaging effect. Ratio between the dose-rates determined with each dosimeter and those obtained with the film was evaluated for both treatment modalities. For the LGK, the ratio decreased as the dosimeter size increased and remained constant for collimator diameters larger than 8 mm. The same behaviour was observed for the linac and the ratio increased with field size, independent of the dosimeter used. These behaviours could be explained as an averaging volume effect due to dose gradient and lack of electronic equilibrium. Evaluation of the output factors for the LGK collimators indicated that, even when agreement was observed between Monte Carlo simulation and measurements with different dosimeters, this does not warrant that the absorbed dose to water rate in the field was properly known and thus, investigation of the reference dosimetry should be an important issue. These results indicated that alanine dosimeter provides a high degree of accuracy but cannot be used in fields smaller than 20 mm diameter. Gafchromic film can be considered as a suitable methodology for reference dosimetry. TLD dosimeters are not appropriate in fields smaller than 10 mm diameters. PMID:23671677

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

Papadimitroulas, P; Kagadis, GC; Loudos, G

Purpose: Our purpose is to evaluate the administered absorbed dose in pediatric, nuclear imaging studies. Monte Carlo simulations with the incorporation of pediatric computational models can serve as reference for the accurate determination of absorbed dose. The procedure of the calculated dosimetric factors is described, while a dataset of reference doses is created. Methods: Realistic simulations were executed using the GATE toolkit and a series of pediatric computational models, developed by the “IT'IS Foundation”. The series of the phantoms used in our work includes 6 models in the range of 5–14 years old (3 boys and 3 girls). Pre-processing techniquesmore » were applied to the images, to incorporate the phantoms in GATE simulations. The resolution of the phantoms was set to 2 mm3. The most important organ densities were simulated according to the GATE “Materials Database”. Several used radiopharmaceuticals in SPECT and PET applications are being tested, following the EANM pediatric dosage protocol. The biodistributions of the several isotopes used as activity maps in the simulations, were derived by the literature. Results: Initial results of absorbed dose per organ (mGy) are presented in a 5 years old girl from the whole body exposure to 99mTc - SestaMIBI, 30 minutes after administration. Heart, kidney, liver, ovary, pancreas and brain are the most critical organs, in which the S-factors are calculated. The statistical uncertainty in the simulation procedure was kept lower than 5%. The Sfactors for each target organ are calculated in Gy/(MBq*sec) with highest dose being absorbed in kidneys and pancreas (9.29*10{sup 10} and 0.15*10{sup 10} respectively). Conclusion: An approach for the accurate dosimetry on pediatric models is presented, creating a reference dosage dataset for several radionuclides in children computational models with the advantages of MC techniques. Our study is ongoing, extending our investigation to other reference models and evaluating the results with clinical estimated doses.« less

Radiation-induced cytogenetic and hematologic effects on aquatic biota within the Chernobyl exclusion zone.

PubMed

Gudkov, D I; Shevtsova, N L; Pomortseva, N A; Dzyubenko, E V; Kaglyan, A E; Nazarov, A B

2016-01-01

During 1998-2014 the rate of chromosomal aberrations in embryo tissues of the pond snail (Lymnaea stagnalis) and root meristems of higher aquatic plants, and also hematologic indexes of mantle liquid of the adult snails and peripheral blood of fishes in water bodies within the Chernobyl exclusion zone (EZ) was studied. The absorbed dose rate for hydrobionts from water bodies of the EZ registered in a range from 0.25 to 420 μGy h(-1) and in the reference ones - up to 0.09 μGy h(-1). The level of chromosomal aberrations in the molluscs from the most contaminated water bodies of the EZ was registered within range of 18-27% and for the molluscs from the reference lakes this index was on the average 1.5% with the maximal values 2.3%. The rate of chromosomal aberrations in root meristematic cells of higher aquatic plants from the contaminated lakes of the EZ was in range of 7-17% and in the plants from reference water bodies was not exceed 2.1%. The positive correlation between chromosomal aberration rate and absorbed dose rate in the pond snail's embryos and root meristems of higher aquatic plants in water bodies of the EZ was registered. Analysis of hemolymph structure of snails from the most contaminated water bodies showed a high rate of dead and phagocytic cells as well as decrease of the young amoebocytes quantity. Hematologic research of fish allows to determine on the one hand an insignificant changes of leukogram structure, and from the other hand a high level of red cells with different abnormalities in the peripheral blood of fishes from the water bodies with high levels of radioactive contamination. It is suppose that qualitative indexes of red cells in peripheral blood of fish are more sensitive to long-term radiation impact in comparison with elements of white blood, which can be used for conducting of the hematologic monitoring of radioactive contaminated water bodies. Copyright © 2015 Elsevier Ltd. All rights reserved.

Novel spectrometers for environmental dose rate monitoring.

PubMed

Kessler, P; Behnke, B; Dabrowski, R; Dombrowski, H; Röttger, A; Neumaier, S

2018-07-01

A new generation of dosemeters, based on the scintillators LaBr 3 , CeBr 3 and SrI 2 , read out with conventional photomultipliers, to be used in the field of environmental gamma-radiation monitoring, was investigated. The main features of these new instruments and especially their outdoor performance, studied by long-term investigations under real weather conditions, are presented. The systems were tested at the reference sites for environmental radiation of the Physikalisch-Technische Bundesanstalt. The measurements are compared with that of well characterized classical dose rate reference instruments to demonstrate the suitability of new spectrometers for environmental dose rate monitoring even in adverse weather conditions. Their potential to replace the (mainly Geiger Müller based) dose rate meters operated in about 5000 European early waning network stations as well as in environmental radiation monitoring in general is shown. Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.

Dosimetric changes with computed tomography automatic tube-current modulation techniques.

PubMed

Spampinato, Sofia; Gueli, Anna Maria; Milone, Pietro; Raffaele, Luigi Angelo

2018-04-06

The study is aimed at a verification of dose changes for a computed tomography automatic tube-current modulation (ATCM) technique. For this purpose, anthropomorphic phantom and Gafchromic ® XR-QA2 films were used. Radiochromic films were cut according to the shape of two thorax regions. The ATCM algorithm is based on noise index (NI) and three exam protocols with different NI were chosen, of which one was a reference. Results were compared with dose values displayed by the console and with Poisson statistics. The information obtained with radiochromic films has been normalized with respect to the NI reference value to compare dose percentage variations. Results showed that, on average, the information reported by the CT console and calculated values coincide with measurements. The study allowed verification of the dose information reported by the CT console for an ATCM technique. Although this evaluation represents an estimate, the method can be a starting point for further studies.

Extended range radiation dose-rate monitor

DOEpatents

Valentine, Kenneth H.

1988-01-01

An extended range dose-rate monitor is provided which utilizes the pulse pileup phenomenon that occurs in conventional counting systems to alter the dynamic response of the system to extend the dose-rate counting range. The current pulses from a solid-state detector generated by radiation events are amplified and shaped prior to applying the pulses to the input of a comparator. The comparator generates one logic pulse for each input pulse which exceeds the comparator reference threshold. These pulses are integrated and applied to a meter calibrated to indicate the measured dose-rate in response to the integrator output. A portion of the output signal from the integrator is fed back to vary the comparator reference threshold in proportion to the output count rate to extend the sensitive dynamic detection range by delaying the asymptotic approach of the integrator output toward full scale as measured by the meter.

Evaluation of the dosimetric properties of a synthetic single crystal diamond detector in high energy clinical proton beams.

PubMed

Mandapaka, A K; Ghebremedhin, A; Patyal, B; Marinelli, Marco; Prestopino, G; Verona, C; Verona-Rinati, G

2013-12-01

To investigate the dosimetric properties of a synthetic single crystal diamond Schottky diode for accurate relative dose measurements in large and small field high-energy clinical proton beams. The dosimetric properties of a synthetic single crystal diamond detector were assessed by comparison with a reference Markus parallel plate ionization chamber, an Exradin A16 microionization chamber, and Exradin T1a ion chamber. The diamond detector was operated at zero bias voltage at all times. Comparative dose distribution measurements were performed by means of Fractional depth dose curves and lateral beam profiles in clinical proton beams of energies 155 and 250 MeV for a 14 cm square cerrobend aperture and 126 MeV for 3, 2, and 1 cm diameter circular brass collimators. ICRU Report No. 78 recommended beam parameters were used to compare fractional depth dose curves and beam profiles obtained using the diamond detector and the reference ionization chamber. Warm-up∕stability of the detector response and linearity with dose were evaluated in a 250 MeV proton beam and dose rate dependence was evaluated in a 126 MeV proton beam. Stem effect and the azimuthal angle dependence of the diode response were also evaluated. A maximum deviation in diamond detector signal from the average reading of less than 0.5% was found during the warm-up irradiation procedure. The detector response showed a good linear behavior as a function of dose with observed deviations below 0.5% over a dose range from 50 to 500 cGy. The detector response was dose rate independent, with deviations below 0.5% in the investigated dose rates ranging from 85 to 300 cGy∕min. Stem effect and azimuthal angle dependence of the diode signal were within 0.5%. Fractional depth dose curves and lateral beam profiles obtained with the diamond detector were in good agreement with those measured using reference dosimeters. The observed dosimetric properties of the synthetic single crystal diamond detector indicate that its behavior is proton energy independent and dose rate independent in the investigated energy and dose rate range and it is suitable for accurate relative dosimetric measurements in large as well as in small field high energy clinical proton beams.

SU-E-T-602: Patient-Specific Online Dose Verification Based On Transmission Detector Measurements

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

Thoelking, J; Yuvaraj, S; Jens, F

Purpose: Intensity modulated radiotherapy requires a comprehensive quality assurance program in general and ideally independent verification of dose delivery. Since conventional 2D detector arrays allow only pre-treatment verification, there is a debate concerning the need of online dose verification. This study presents the clinical performance, including dosimetric plan verification in 2D as well as in 3D and the error detection abilities of a new transmission detector (TD) for online dose verification of 6MV photon beam. Methods: To validate the dosimetric performance of the new device, dose reconstruction based on TD measurements were compared to a conventional pre-treatment verification method (reference)more » and treatment planning system (TPS) for 18 IMRT and VMAT treatment plans. Furthermore, dose reconstruction inside the patient based on TD read-out was evaluated by comparing various dose volume indices and 3D gamma evaluations against independent dose computation and TPS. To investigate the sensitivity of the new device, different types of systematic and random errors for leaf positions and linac output were introduced in IMRT treatment sequences. Results: The 2D gamma index evaluation of transmission detector based dose reconstruction showed an excellent agreement for all IMRT and VMAT plans compared to reference measurements (99.3±1.2)% and TPS (99.1±0.7)%. Good agreement was also obtained for 3D dose reconstruction based on TD read-out compared to dose computation (mean gamma value of PTV = 0.27±0.04). Only a minimal dose underestimation within the target volume was observed when analyzing DVH indices (<1%). Positional errors in leaf banks larger than 1mm and errors in linac output larger than 2% could clearly identified with the TD. Conclusion: Since 2D and 3D evaluations for all IMRT and VMAT treatment plans were in excellent agreement with reference measurements and dose computation, the new TD is suitable to qualify for routine treatment plan verification. Funding Support, Disclosures, and Conflict of Interest: COIs: Frank Lohr: Elekta: research grant, travel grants, teaching honoraria IBA: research grant, travel grants, teaching honoraria, advisory board C-Rad: board honoraria, travel grants Frederik Wenz: Elekta: research grant, teaching honoraria, consultant, advisory board Zeiss: research grant, teaching honoraria, patent Hansjoerg Wertz: Elekta: research grant, teaching honoraria IBA: research grant.« less

Opportunities to improve the in vivo measurement of manganese in human hands.

PubMed

Aslam; Chettle, D R; Pejović-Milić, A; Waker, A J

2009-01-07

Manganese (Mn) is an element which is both essential for regulating neurological and skeletal functions in the human body and also toxic when humans are exposed to excessive levels. Its excessive inhalation as a result of exposure through industrial and environmental emissions can cause neurological damage, which may manifest as memory deficit, loss of motor control and reduction in the refinement of certain body motions. A number of clinical studies demonstrate that biological monitoring of Mn exposure using body fluids, particularly blood, plasma/serum and urine is of very limited use and reflect only the most recent exposure and rapidly return to within normal ranges. In this context, a non-invasive neutron activation technique has been developed at the McMaster University accelerator laboratory that could provide an alternative to measure manganese stored in the bones of exposed subjects. In a first pilot study we conducted recently on non-exposed human subjects to measure the ratio of Mn to Ca in hand bones, it was determined that the technique needed further development to improve the precision of the measurements. It could be achieved by improving the minimum detection limit (MDL) of the system from 2.1 microg Mn/g Ca to the reference value of 0.6 microg g(-1) Ca (range: 0.16-0.78 microg Mn/g Ca) for the non-exposed population. However, the developed procedure might still be a suitable means of screening patients and people exposed to excessive amounts of Mn, who could develop many-fold increased levels of Mn in bones as demonstrated through various animal studies. To improve the MDL of the technique to the expected levels of Mn in a reference population, the present study investigates further optimization of irradiation conditions, which includes the optimal selection of proton beam energy, beam current and irradiation time and the effect of upgrading the 4pi detection system. The maximum local dose equivalent that could be given to the hand as a result of irradiation was constrained to be less than 150 mSv as opposed to the previously imposed dose equivalent limit of 20 mSv. A maximum beam current, which could be delivered on the lithium target to produce neutrons, was restricted to 500 microA. The length of irradiation intervals larger than 10 min, was considered inconvenient and impractical to implement with Mn measurements in humans. To fulfil the requirements for developing a protocol for in vivo bone Mn measurements, a revised estimate of the dose equivalent has been presented here. Beam energy of 1.98 MeV was determined to be optimal to complete the irradiation procedure within 10 min using 500 microA beam current. The local dose equivalent given to hand was estimated as 118 mSv, which is lower by a factor of 1.5 compared to that of 2.00 MeV. The optimized beam parameters are expected to improve the currently obtained detection limit of 2.1 microg Mn/g Ca to 0.6 microg Mn/g Ca. Using this dose equivalent delivered to the central location of the hand, the average dose equivalent to the hand of 74 mSv and an effective dose of approximately 70 microSv will be accompanying the non-invasive, in vivo measurements of bone Mn, which is little over the chest radiograph examination dose.

Opportunities to improve the in vivo measurement of manganese in human hands

NASA Astrophysics Data System (ADS)

Aslam; Chettle, D. R.; Pejović-Milić, A.; Waker, A. J.

2009-01-01

Manganese (Mn) is an element which is both essential for regulating neurological and skeletal functions in the human body and also toxic when humans are exposed to excessive levels. Its excessive inhalation as a result of exposure through industrial and environmental emissions can cause neurological damage, which may manifest as memory deficit, loss of motor control and reduction in the refinement of certain body motions. A number of clinical studies demonstrate that biological monitoring of Mn exposure using body fluids, particularly blood, plasma/serum and urine is of very limited use and reflect only the most recent exposure and rapidly return to within normal ranges. In this context, a non-invasive neutron activation technique has been developed at the McMaster University accelerator laboratory that could provide an alternative to measure manganese stored in the bones of exposed subjects. In a first pilot study we conducted recently on non-exposed human subjects to measure the ratio of Mn to Ca in hand bones, it was determined that the technique needed further development to improve the precision of the measurements. It could be achieved by improving the minimum detection limit (MDL) of the system from 2.1 µg Mn/g Ca to the reference value of 0.6 µg g-1 Ca (range: 0.16-0.78 µg Mn/g Ca) for the non-exposed population. However, the developed procedure might still be a suitable means of screening patients and people exposed to excessive amounts of Mn, who could develop many-fold increased levels of Mn in bones as demonstrated through various animal studies. To improve the MDL of the technique to the expected levels of Mn in a reference population, the present study investigates further optimization of irradiation conditions, which includes the optimal selection of proton beam energy, beam current and irradiation time and the effect of upgrading the 4π detection system. The maximum local dose equivalent that could be given to the hand as a result of irradiation was constrained to be less than 150 mSv as opposed to the previously imposed dose equivalent limit of 20 mSv. A maximum beam current, which could be delivered on the lithium target to produce neutrons, was restricted to 500 µA. The length of irradiation intervals larger than 10 min, was considered inconvenient and impractical to implement with Mn measurements in humans. To fulfil the requirements for developing a protocol for in vivo bone Mn measurements, a revised estimate of the dose equivalent has been presented here. Beam energy of 1.98 MeV was determined to be optimal to complete the irradiation procedure within 10 min using 500 µA beam current. The local dose equivalent given to hand was estimated as 118 mSv, which is lower by a factor of 1.5 compared to that of 2.00 MeV. The optimized beam parameters are expected to improve the currently obtained detection limit of 2.1 µg Mn/g Ca to 0.6 µg Mn/g Ca. Using this dose equivalent delivered to the central location of the hand, the average dose equivalent to the hand of 74 mSv and an effective dose of approximately 70 µSv will be accompanying the non-invasive, in vivo measurements of bone Mn, which is little over the chest radiograph examination dose.

Safety of phase I clinical trials with monoclonal antibodies in Germany--the regulatory requirements viewed in the aftermath of the TGN1412 disaster.

PubMed

Liedert, B; Bassus, S; Schneider, C K; Kalinke, U; Löwer, J

2007-01-01

This review summarizes scientific, ethical and regulatory aspects of Phase I clinical trials with monoclonal antibodies. The current standard requirements for pre-clinical testing and for clinical study design are presented. The scientific considerations discussed herein are generally applicable, the view on legal requirements for clinical trials refer to the German jurisdiction only. The adverse effects associated with the TGN1412 Phase I trial indicate that the predictive value of pre-clinical animal models requires reevaluation and that, in certain cases, some issues of clinical trial protocols such as dose fixing may need refinement or redesign. Concrete safety measures, which have been proposed as a consequence of the TGN1412 event include introduction of criteria for high-risk antibodies, sequential inclusion of trial participants and implementation of pre-Phase I studies where dose calculation is based on the pre-clinical No Effect Level instead of the No Observed Adverse Effect Level. The recently established European clinical trials database (EUDRACT Database) is a further safety tool to expedite the sharing of relevant information between scientific authorities.

Natural radioactivity and radon exhalation rates in man-made tiles used as building materials in Japan.

PubMed

Iwaoka, K; Hosoda, M; Suwankot, N; Omori, Y; Ishikawa, T; Yonehara, H; Tokonami, S

2015-11-01

Man-made tiles frequently used in Japan were collected, and activity concentrations and radon ((222)Rn) exhalation rates in these tiles were measured. Dose estimations for inhabitants living in houses built using these tiles were also carried out. The activity concentrations of (226)Ra, (228)Ra and (40)K in the man-made tiles were 31-170, 35-110 and 260-980 Bq kg(-1), respectively. The (222)Rn exhalation rates in the tiles were 8.8-21 μBq m(-2) s(-1). The ranges of experimental activity concentrations and (222)Rn exhalation rates were almost identical to those of natural rocks used as typical building materials in Japan. The maximum value of effective dose to inhabitants living in houses built with the man-made tiles was 0.14 mSv y(-1), which is lower than the reference level range (1-20 mSv y(-1)) for abnormally high levels of natural background radiation published in the ICRP Publication 103. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Characterization of a commercial hybrid iterative and model-based reconstruction algorithm in radiation oncology

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

Price, Ryan G.; Vance, Sean; Cattaneo, Richard

2014-08-15

Purpose: Iterative reconstruction (IR) reduces noise, thereby allowing dose reduction in computed tomography (CT) while maintaining comparable image quality to filtered back-projection (FBP). This study sought to characterize image quality metrics, delineation, dosimetric assessment, and other aspects necessary to integrate IR into treatment planning. Methods: CT images (Brilliance Big Bore v3.6, Philips Healthcare) were acquired of several phantoms using 120 kVp and 25–800 mAs. IR was applied at levels corresponding to noise reduction of 0.89–0.55 with respect to FBP. Noise power spectrum (NPS) analysis was used to characterize noise magnitude and texture. CT to electron density (CT-ED) curves were generatedmore » over all IR levels. Uniformity as well as spatial and low contrast resolution were quantified using a CATPHAN phantom. Task specific modulation transfer functions (MTF{sub task}) were developed to characterize spatial frequency across objects of varied contrast. A prospective dose reduction study was conducted for 14 patients undergoing interfraction CT scans for high-dose rate brachytherapy. Three physicians performed image quality assessment using a six-point grading scale between the normal-dose FBP (reference), low-dose FBP, and low-dose IR scans for the following metrics: image noise, detectability of the vaginal cuff/bladder interface, spatial resolution, texture, segmentation confidence, and overall image quality. Contouring differences between FBP and IR were quantified for the bladder and rectum via overlap indices (OI) and Dice similarity coefficients (DSC). Line profile and region of interest analyses quantified noise and boundary changes. For two subjects, the impact of IR on external beam dose calculation was assessed via gamma analysis and changes in digitally reconstructed radiographs (DRRs) were quantified. Results: NPS showed large reduction in noise magnitude (50%), and a slight spatial frequency shift (∼0.1 mm{sup −1}) with application of IR at L6. No appreciable changes were observed for CT-ED curves between FBP and IR levels [maximum difference ∼13 HU for bone (∼1% difference)]. For uniformity, differences were ∼1 HU between FBP and IR. Spatial resolution was well conserved; the largest MTF{sub task} decrease between FBP and IR levels was 0.08 A.U. No notable changes in low-contrast detectability were observed and CNR increased substantially with IR. For the patient study, qualitative image grading showed low-dose IR was equivalent to or slightly worse than normal dose FBP, and is superior to low-dose FBP (p < 0.001 for noise), although these did not translate to differences in CT number, contouring ability, or dose calculation. The largest CT number discrepancy from FBP occurred at a bone/tissue interface using the most aggressive IR level [−1.2 ± 4.9 HU (range: −17.6–12.5 HU)]. No clinically significant contour differences were found between IR and FBP, with OIs and DSCs ranging from 0.85 to 0.95. Negligible changes in dose calculation were observed. DRRs preserved anatomical detail with <2% difference in intensity from FBP combined with aggressive IRL6. Conclusions: These results support integrating IR into treatment planning. While slight degradation in edges and shift in texture were observed in phantom, patient results show qualitative image grading, contouring ability, and dosimetric parameters were not adversely affected.« less

SU-E-T-117: Analysis of the ArcCHECK Dosimetry Gamma Failure Using the 3DVH System

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

Cho, S; Choi, W; Lee, H

2015-06-15

Purpose: To evaluate gamma analysis failure for the VMAT patient specific QA using ArcCHECK cylindrical phantom. The 3DVH system(Sun Nuclear, FL) was used to analyze the dose difference statistic between measured dose and treatment planning system calculated dose. Methods: Four case of gamma analysis failure were selected retrospectively. Our institution gamma analysis indexes were absolute dose, 3%/3mm and 90%pass rate in the ArcCHECK dosimetry. The collapsed cone convolution superposition (CCCS) dose calculation algorithm for VMAT was used. Dose delivery was performed with Elekta Agility. The A1SL(standard imaging, WI) and cavity plug were used for point dose measurement. Delivery QA plansmore » and images were used for 3DVH Reference data instead of patient plan and image. The measured data of ‘.txt’ file was used for comparison at diodes to acquire a global dose level. The,.acml’ file was used for AC-PDP and to calculated point dose. Results: The global dose of 3DVH was calculated as 1.10 Gy, 1.13, 1.01 and 0.2 Gy respectively. The global dose of 0.2 Gy case was induced by distance discrepancy. The TPS calculated point dose of was 2.33 Gy to 2.77 Gy and 3DVH calculated dose was 2.33 Gy to 2.68 Gy. The maximum dose differences were −2.83% and −3.1% for TPS vs. measured dose and TPS vs. 3DVH calculated respectively in the same case. The difference between measured and 3DVH was 0.1% in that case. The 3DVH gamma pass rate was 98% to 99.7%. Conclusion: We found the TPS calculation error by 3DVH calculation using ArcCHECK measured dose. It seemed that our CCCS algorithm RTP system over estimated at the central region and underestimated scattering at the peripheral diode detector point. The relative gamma analysis and point dose measurement would be recommended for VMAT DQA in the gamma failure case of ArcCHECK dosimetry.« less

Bioavailability of cyanide after consumption of a single meal of foods containing high levels of cyanogenic glycosides: a crossover study in humans.

PubMed

Abraham, Klaus; Buhrke, Thorsten; Lampen, Alfonso

2016-03-01

The acute toxicity of cyanide is determined by its peak levels reached in the body. Compared to the ingestion of free cyanide, lower peak levels may be expected after consumption of foods containing cyanogenic glycosides with the same equivalent dose of cyanide. This is due to possible delayed and/or incomplete release of cyanide from the cyanogenic glycosides depending on many factors. Data on bioavailability of cyanide after consumption of foods containing high levels of cyanogenic glycosides as presented herein were necessary to allow a meaningful risk assessment for these foods. A crossover study was carried out in 12 healthy adults who consumed persipan paste (equivalent total cyanide: 68 mg/kg), linseed (220 mg/kg), bitter apricot kernels (about 3250 mg/kg), and fresh cassava roots (76-150 mg/kg), with each "meal" containing equivalents of 6.8 mg cyanide. Cyanide levels were determined in whole blood using a GC-MS method with K(13)C(15)N as internal standard. Mean levels of cyanide at the different time points were highest after consumption of cassava (15.4 µM, after 37.5 min) and bitter apricot kernels (14.3 µM, after 20 min), followed by linseed (5.7 µM, after 40 min) and 100 g persipan (1.3 µM, after 105 min). The double dose of 13.6 mg cyanide eaten with 200 g persipan paste resulted in a mean peak level of 2.9 µM (after 150 min). An acute reference dose of 0.075 mg/kg body weight was derived being valid for a single application/meal of cyanides or hydrocyanic acid as well as of unprocessed foods with cyanogenic glycosides also containing the accompanying intact β-glucosidase. For some of these foods, this approach may be overly conservative due to delayed release of cyanide, as demonstrated for linseed. In case of missing or inactivated β-glucosidase, the hazard potential is much lower.

Reducing radiation dose to the female breast during CT coronary angiography: A simulation study comparing breast shielding, angular tube current modulation, reduced kV, and partial angle protocols using an unknown-location signal-detectability metric

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

Rupcich, Franco; Gilat Schmidt, Taly; Badal, Andreu

2013-08-15

Purpose: The authors compared the performance of five protocols intended to reduce dose to the breast during computed tomography (CT) coronary angiography scans using a model observer unknown-location signal-detectability metric.Methods: The authors simulated CT images of an anthropomorphic female thorax phantom for a 120 kV reference protocol and five “dose reduction” protocols intended to reduce dose to the breast: 120 kV partial angle (posteriorly centered), 120 kV tube-current modulated (TCM), 120 kV with shielded breasts, 80 kV, and 80 kV partial angle (posteriorly centered). Two image quality tasks were investigated: the detection and localization of 4-mm, 3.25 mg/ml and 1-mm,more » 6.0 mg/ml iodine contrast signals randomly located in the heart region. For each protocol, the authors plotted the signal detectability, as quantified by the area under the exponentially transformed free response characteristic curve estimator (A-caret{sub FE}), as well as noise and contrast-to-noise ratio (CNR) versus breast and lung dose. In addition, the authors quantified each protocol's dose performance as the percent difference in dose relative to the reference protocol achieved while maintaining equivalent A-caret{sub FE}.Results: For the 4-mm signal-size task, the 80 kV full scan and 80 kV partial angle protocols decreased dose to the breast (80.5% and 85.3%, respectively) and lung (80.5% and 76.7%, respectively) with A-caret{sub FE} = 0.96, but also resulted in an approximate three-fold increase in image noise. The 120 kV partial protocol reduced dose to the breast (17.6%) at the expense of increased lung dose (25.3%). The TCM algorithm decreased dose to the breast (6.0%) and lung (10.4%). Breast shielding increased breast dose (67.8%) and lung dose (103.4%). The 80 kV and 80 kV partial protocols demonstrated greater dose reductions for the 4-mm task than for the 1-mm task, and the shielded protocol showed a larger increase in dose for the 4-mm task than for the 1-mm task. In general, the CNR curves indicate a similar relative ranking of protocol performance as the corresponding A-caret{sub FE} curves, however, the CNR metric overestimated the performance of the shielded protocol for both tasks, leading to corresponding underestimates in the relative dose increases compared to those obtained when using the A-caret{sub FE} metric.Conclusions: The 80 kV and 80 kV partial angle protocols demonstrated the greatest reduction to breast and lung dose, however, the subsequent increase in image noise may be deemed clinically unacceptable. Tube output for these protocols can be adjusted to achieve a more desirable noise level with lesser breast dose savings. Breast shielding increased breast and lung dose when maintaining equivalent A-caret{sub FE}. The results demonstrated that comparisons of dose performance depend on both the image quality metric and the specific task, and that CNR may not be a reliable metric of signal detectability.« less

Do changes in biomarkers from space radiation reflect dose or risk?

NASA Astrophysics Data System (ADS)

Brooks, A.

The space environment is made up of many different kinds of radiation so that the proper use of biomarkers is essential to estimate radiation risk. This presentation will evaluate differences between biomarkers of dose and risk and demonstrate why they should not be confused following radiation exposures in deep space. Dose is a physical quantity, while risk is a biological quantity. Many examples exist w ereh dose or changes in biomarkers of dose are inappropriately used as predictors of risk. Without information on the biology of the system, the biomarkers of dose provide little help in predicting risk in tissues or radiation exposure types where no excess risk can be demonstrated. Many of these biomarkers of dose only reflect changes in radiation dose or exposure. However, these markers are often incorrectly used to predict risk. For example, exposure of the trachea or of the deep lung to high-LET alpha particles results in similar changes in the biomarker chromosome damage in these two tissues. Such an observation would predict that the risk for cancer induction would be similar in these two tissues. It has been noted , however, that there has never been a tracheal tumor observed in rats that inhaled radon, but with the same exposure, large numbers of tumors were produced in the deep lung. The biology of the different tissues is the major determinant of the risk rather than the radiation dose. Recognition of this fact has resulted in the generation of tissue weighting factors for use in radiation protection. When tissue weighting factors are used the values derived are still called "dose". It is important to recognize that tissue specific observations have been corrected to reflect risk, and therefore should no longer be viewed as dose. The relative biological effectiveness (RBE) is also used to estimate radiation risk. The use of biomarkers to derive RBE is a difficult since it involves the use of a biological response to a standard low-LET reference radiation. Following low-LET radiation exposure, the biological response often does not increase as a linear function of dose. Thus, the RBE and the subsequent risk predicted is dependent on the dose where the two radiation types are compared. To avoid this problem the standard procedure is to use the dose and dose-rate response and compare the linear components of the two r diation exposures. Important riska comparisons are often done at very low doses, where the reference radiation may either increase or decrease as a function of dose. Since the low-LET exposure often does not produce a significant change above the background level of damage, the derived RBE factors can become very large.Studies using micronuclei as biomarkers following exposure to mono-energetic neutrons, x-rays and gamma rays delivered at very low doses (up to 0.10 Gy) demonstrated the differences in the shape of each dose-response relationship and the problems associated with the RBE. These studies show that RBE may not accurately reflect the hazards or risk associated with space radiation exposure. As additional measures of biological change are developed, it may become possible to base risk on biological change and not on changes in radiation doses. Research funded through grants # DE-FG03-99ER62787 from DOE Office of Biological and Environmental Research and RO1 CA74053-01 from NIH/NASA to Washington State University Tri-Cities.

Ozonation of the pharmaceutical compound ranitidine: reactivity and kinetic aspects.

PubMed

Rivas, Javier; Gimeno, Olga; Encinas, Angel; Beltrán, Fernando

2009-07-01

Ranitidine has been ozonated under different operating conditions of pH, applied ozone dose, initial ranitidine concentration and presence or absence of free radical inhibitors. Results of ranitidine evolution with time indicate a high reactivity of this compound with molecular ozone. Mineralization levels achieved in the order of 20-25% suggest that the (CH3)2-N-CH2- moiety bonded to the furan ring could be separated from the rest of the ranitidine structure and further mineralized. Only alkaline conditions (pH=11) are capable of increasing TOC conversion up to values close to 70%. Determination of the direct ozonation rate constant for ranitidine by means of competitive kinetics reveals an unacceptable dependence of the aforementioned constant with the reference compound reactivity. It is hypothesised that only reference compounds with reactivity similar to the target species should be used.

Sci—Thur AM: YIS - 11: Estimation of Bladder-Wall Cumulative Dose in Multi-Fraction Image-Based Gynaecological Brachytherapy Using Deformable Point Set Registration

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

Zakariaee, R; Brown, C J; Hamarneh, G

2014-08-15

Dosimetric parameters based on dose-volume histograms (DVH) of contoured structures are routinely used to evaluate dose delivered to target structures and organs at risk. However, the DVH provides no information on the spatial distribution of the dose in situations of repeated fractions with changes in organ shape or size. The aim of this research was to develop methods to more accurately determine geometrically localized, cumulative dose to the bladder wall in intracavitary brachytherapy for cervical cancer. The CT scans and treatment plans of 20 cervical cancer patients were used. Each patient was treated with five high-dose-rate (HDR) brachytherapy fractions ofmore » 600cGy prescribed dose. The bladder inner and outer surfaces were delineated using MIM Maestro software (MIM Software Inc.) and were imported into MATLAB (MathWorks) as 3-dimensional point clouds constituting the “bladder wall”. A point-set registration toolbox for MATLAB, Coherent Point Drift (CPD), was used to non-rigidly transform the bladder-wall points from four of the fractions to the coordinate system of the remaining (reference) fraction, which was chosen to be the emptiest bladder for each patient. The doses were accumulated on the reference fraction and new cumulative dosimetric parameters were calculated. The LENT-SOMA toxicity scores of these patients were studied against the cumulative dose parameters. Based on this study, there was no significant correlation between the toxicity scores and the determined cumulative dose parameters.« less

Optimisation of radiation dose and image quality in mobile neonatal chest radiography.

PubMed

Hinojos-Armendáriz, V I; Mejía-Rosales, S J; Franco-Cabrera, M C

2018-05-01

To optimise the radiation dose and image quality for chest radiography in the neonatal intensive care unit (NICU) by increasing the mean beam energy. Two techniques for the acquisition of NICU AP chest X-ray images were compared for image quality and radiation dose. 73 images were acquired using a standard technique (56 kV, 3.2 mAs and no additional filtration) and 90 images with a new technique (62 kV, 2 mAs and 2 mm Al filtration). The entrance surface air kerma (ESAK) was measured using a phantom and compared between the techniques and against established diagnostic reference levels (DRL). Images were evaluated using seven image quality criteria independently by three radiologists. Images quality and radiation dose were compared statistically between the standard and new techniques. The maximum ESAK for the new technique was 40.20 μGy, 43.7% of the ESAK of the standard technique. Statistical evaluation demonstrated no significant differences in image quality between the two acquisition techniques. Based on the techniques and acquisition factors investigated within this study, it is possible to lower the radiation dose without any significant effects on image quality by adding filtration (2 mm Al) and increasing the tube potential. Such steps are relatively simple to undertake and as such, other departments should consider testing and implementing this dose reduction strategy within clinical practice where appropriate. Copyright © 2017 The College of Radiographers. Published by Elsevier Ltd. All rights reserved.

Effects of Different Types of Statins on Lipid Profile: A Perspective on Asians.

PubMed

Meor Anuar Shuhaili, Meor Fairuz Rizal; Samsudin, Intan Nureslyna; Stanslas, Johnson; Hasan, Shariful; Thambiah, Subashini C

2017-04-01

The present review aimed at reviewing the effects of different statins on lipid profile, particularly in Asians. PubMed searches were conducted using the keywords 'statin, effect, and lipid profile' from database inception through March 2016. In this review, 718 articles were retrieved from the primary search. After reviewing the titles, abstracts, and full texts, we found that 59 studies met our inclusion criteria. These also included subsequent reference searches of retrieved articles. CURVES study compared the effect on lipid profile between atorvastatin and other statins. This study demonstrated that low-density lipoprotein cholesterol (LDL-C), total cholesterol (TC), and triglycerides (TG) were reduced more with atorvastatin compared to simvastatin, pravastatin, lovastatin, and fluvastatin. However, simvastatin provided a greater elevation of high-density lipoprotein cholesterol (HDL-C) compared to atorvastatin. The STELLAR trial was based on dose-to-dose comparisons between atorvastatin and rosuvastatin efficacy in reducing LDL-C. Te present study also revealed that as the doses of rosuvastatin, simvastatin, and pravastatin increased, HDL-C also increased, with rosuvastatin having the greatest effect. However, HDL-C levels decreased as the dose of atorvastatin increased. The DISCOVERY study involving the Asian population revealed that the percentage of patients achieving the European goals for LDL-C and TC at 12 weeks was higher in rosuvastatin group compared to atorvastatin group. The effects of statins on lipid profile are dose dependent. Most studies showed that rosuvastatin has the best effect on lipid profile. Prescribing lower doses of statins in Asians seems necessary.

TLD postal dose intercomparison for megavoltage units in Poland.

PubMed

Izewska, J; Gajewski, R; Gwiazdowska, B; Kania, M; Rostkowska, J

1995-08-01

The aim of the TLD pilot study was to investigate and to reduce the uncertainties involved in the measurements of absorbed dose and to improve the consistency in dose determination in the regional radiotherapy centres in Poland. The intercomparison was organized by the SSDL. It covered absorbed dose measurements under reference conditions for Co-60, high energy X-rays and electron beams. LiF powder type MT-N was used for the irradiations and read with the Harshaw TLD reader model 2000B/2000C. The TLD system was set up and an analysis of the factors influencing the accuracy of absorbed dose measurements with TL-detectors was performed to evaluate and minimize the measurement uncertainty. A fading not exceeding 2% in 12 weeks was found. The relative energy correction factor did not exceed 3% for X-rays in the range 4-15 MV, and 4% for electron beams between 6 and 20 MeV. A total of 34 beams was checked. Deviation of +/- 3.5% stated and evaluated dose was considered acceptable for photons and +/- 5% for electron beams. The results for Co-60, high energy X-rays and electron beams showed that there were two, three and no centres, respectively, beyond acceptance levels. The sources of errors for all deviations out of this range were thoroughly investigated, discussed and corrected, however two deviations remained unexplained. The pilot study resulted in an improvement of the accuracy and consistency of dosimetry in Poland.

Patient grouping for dose surveys and establishment of diagnostic reference levels in paediatric computed tomography.

PubMed

Vassileva, J; Rehani, M

2015-07-01

There has been confusion in literature on whether paediatric patients should be grouped according to age, weight or other parameters when dealing with dose surveys. The present work aims to suggest a pragmatic approach to achieve reasonable accuracy for performing patient dose surveys in countries with limited resources. The analysis is based on a subset of data collected within the IAEA survey of paediatric computed tomography (CT) doses, involving 82 CT facilities from 32 countries in Asia, Europe, Africa and Latin America. Data for 6115 patients were collected, in 34.5 % of which data for weight were available. The present study suggests that using four age groups, <1, >1-5, >5-10 and >10-15 y, is realistic and pragmatic for dose surveys in less resourced countries and for the establishment of DRLs. To ensure relevant accuracy of results, data for >30 patients in a particular age group should be collected if patient weight is not known. If a smaller sample is used, patient weight should be recorded and the median weight in the sample should be within 5-10 % from the median weight of the sample for which the DRLs were established. Comparison of results from different surveys should always be performed with caution, taking into consideration the way of grouping of paediatric patients. Dose results can be corrected for differences in patient weight/age group. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

The use of rotation to fentanyl in cancer-related pain

PubMed Central

Dima, Delia; Tomuleasa, Ciprian; Frinc, Ioana; Pasca, Sergiu; Magdo, Lorand; Berindan-Neagoe, Ioana; Muresan, Mihai; Lisencu, Cosmin; Irimie, Alexandru; Zdrenghea, Mihnea

2017-01-01

Pain is commonly diagnosed with respect to cancer and heart diseases, being a major symptom in most neoplastic diseases. Uncontrolled pain leads to a decrease in the quality of life and an increase in the morbidity of the patient. Opioids represent the best analgetic supportive therapy and are frequently used in patients suffering from cancer and experiencing a high level of pain. Opioid treatment starts with a gradual titration of the dose until the minimum effective dose and the maximum tolerated dose are determined. Opioid rotation refers to the switch from one opioid to another in order to get a better response to analgetic therapy and reduce side effects. Fentanyl therapy is recommended to be continued during chemotherapy, radiotherapy, or in the case of surgical intervention. Rotation to fentanyl patches is an efficient and elegant solution for cancer patients, with reduced side effects. Opioid rotation, especially to fentanyl, was shown to increase the quality of life in patients with malignant disease. Finally, rotation to fentanyl is also advantageous from an economic point of view. PMID:28223843

Benefits of an automatic patient dose registry system for interventional radiology and cardiology at five hospitals of the Madrid area.

PubMed

Fernandez-Soto, J M; Ten, J I; Sanchez, R M; España, M; Pifarre, X; Vano, E

2015-07-01

The purpose of this article is to present the results of connecting the interventional radiology and cardiology laboratories of five university hospitals to a unique server using an automatic patient dose registry system (Dose On Line for Interventional Radiology, DOLIR) developed in-house, and to evaluate its feasibility more than a year after its introduction. The system receives and stores demographic and dosimetric parameters included in the MPPS DICOM objects sent by the modalities to a database. A web service provides a graphical interface to analyse the information received. During 2013, the system processed 10 788 procedures (6874 cardiac, 2906 vascular and 1008 neuro interventional). The percentages of patients requiring clinical follow-up due to potential tissue reactions before and after the use of DOLIR are presented. The system allowed users to verify in real-time, if diagnostic (or interventional) reference levels are fulfilled. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Effect of (+)-Methamphetamine on Path Integration Learning, Novel Object Recognition, and Neurotoxicity in Rats

PubMed Central

Herring, Nicole R.; Schaefer, Tori L.; Gudelsky, Gary A.; Vorhees, Charles V.; Williams, Michael T.

2008-01-01

Rationale Methamphetamine (MA) has been implicated in cognitive deficits in humans after chronic use. Animal models of neurotoxic MA exposure reveal persistent damage to monoaminergic systems, but few associated cognitive effects. Objectives Since, questions have been raised about the typical neurotoxic dosing regimen used in animals and whether it adequately models human cumulative drug exposure, these experiments examined two different dosing regimens. Methods Rats were treated with one of two regimens, one the typical neurotoxic regimen (4 × 10 mg/kg every 2 h) and one based on pharmacokinetic modeling (Cho et al. 2001) designed to better represent accumulating plasma concentrations of MA as seen in human users (24 ×1.67 mg/kg once every 15 min); matched for total daily dose. In two separate experiments, dosing regimens were compared for their effects on markers of neurotoxicity or on behavior. Results On markers of neurotoxicity, MA showed decreased DA and 5-HT, and increased glial fibrillary acidic protein and increased corticosterone levels regardless of dosing regimen 3 days post-treatment. Behaviorally, MA-treated groups, regardless of dosing regimen, showed hypoactivity, increased initial hyperactivity to a subsequent MA challenge, impaired novel object recognition, impaired learning in a multiple-T water maze test of path integration, and no differences on spatial navigation or reference memory in the Morris water maze. After behavioral testing, reductions of DA and 5-HT remained. Conclusions MA treatment induces an effect on path integration learning not previously reported. Dosing regimen had no differential effects on behavior or neurotoxicity. PMID:18509623

Effect of +-methamphetamine on path integration learning, novel object recognition, and neurotoxicity in rats.

PubMed

Herring, Nicole R; Schaefer, Tori L; Gudelsky, Gary A; Vorhees, Charles V; Williams, Michael T

2008-09-01

Methamphetamine (MA) has been implicated in cognitive deficits in humans after chronic use. Animal models of neurotoxic MA exposure reveal persistent damage to monoaminergic systems but few associated cognitive effects. Since questions have been raised about the typical neurotoxic dosing regimen used in animals and whether it adequately models human cumulative drug exposure, these experiments examined two different dosing regimens. Rats were treated with one of the two regimens: one based on the typical neurotoxic regimen (4 x 10 mg/kg every 2 h) and one based on pharmacokinetic modeling (Cho AK, Melega WP, Kuczenski R, Segal DS Synapse 39:161-166, 2001) designed to better represent accumulating plasma concentrations of MA as seen in human users (24 x 1.67 mg/kg once every 15 min) matched for total daily dose. In two separate experiments, dosing regimens were compared for their effects on markers of neurotoxicity or on behavior. On markers of neurotoxicity, MA showed decreased dopamine (DA) and 5-HT, increased glial fibrillary acidic protein, and increased corticosterone levels regardless of dosing regimen 3 days post-treatment. Behaviorally, MA-treated groups, regardless of dosing regimen, showed hypoactivity, increased initial hyperactivity to a subsequent MA challenge, impaired novel object recognition, impaired learning in a multiple T water maze test of path integration, and no differences on spatial navigation or reference memory in the Morris water maze. After behavioral testing, reductions of DA and 5-HT remained. MA treatment induces an effect on path integration learning not previously reported. Dosing regimen had no differential effects on behavior or neurotoxicity.

A mathematical approach to beam matching

PubMed Central

Manikandan, A; Nandy, M; Gossman, M S; Sureka, C S; Ray, A; Sujatha, N

2013-01-01

Objective: This report provides the mathematical commissioning instructions for the evaluation of beam matching between two different linear accelerators. Methods: Test packages were first obtained including an open beam profile, a wedge beam profile and a depth–dose curve, each from a 10×10 cm2 beam. From these plots, a spatial error (SE) and a percentage dose error were introduced to form new plots. These three test package curves and the associated error curves were then differentiated in space with respect to dose for a first and second derivative to determine the slope and curvature of each data set. The derivatives, also known as bandwidths, were analysed to determine the level of acceptability for the beam matching test described in this study. Results: The open and wedged beam profiles and depth–dose curve in the build-up region were determined to match within 1% dose error and 1-mm SE at 71.4% and 70.8% for of all points, respectively. For the depth–dose analysis specifically, beam matching was achieved for 96.8% of all points at 1%/1 mm beyond the depth of maximum dose. Conclusion: To quantify the beam matching procedure in any clinic, the user needs to merely generate test packages from their reference linear accelerator. It then follows that if the bandwidths are smooth and continuous across the profile and depth, there is greater likelihood of beam matching. Differentiated spatial and percentage variation analysis is appropriate, ideal and accurate for this commissioning process. Advances in knowledge: We report a mathematically rigorous formulation for the qualitative evaluation of beam matching between linear accelerators. PMID:23995874

Increased 5-hydroxymethylcytosine and Ten-eleven Translocation Protein Expression in Ultraviolet B-irradiated HaCaT Cells

PubMed Central

Wang, Dan; Huang, Jin-Hua; Zeng, Qing-Hai; Gu, Can; Ding, Shu; Lu, Jian-Yun; Chen, Jing; Yang, Sheng-Bo

2017-01-01

Background: DNA hydroxymethylation refers to a chemical modification process in which 5-methylcytosine (5mC) is catalyzed to 5- hydroxymethylcytosine (5hmC) by ten-eleven translocation (TET) family proteins. Recent studies have revealed that aberrant TETs expression or 5hmC level may play important roles in the occurrence and development of various pathological and physiological processes including cancer and aging. This study aimed to explore the relation between aberrant DNA hydroxymethylation with skin photoaging and to investigate the levels of TETs, 5mC, and 5hmC expression 24 h after 40 mJ/cm2 and 80 mJ/cm2 doses of ultraviolet B (UVB) irradiation to HaCaT cells. Methods: To explore whether aberrant DNA hydroxymethylation is also related to skin photoaging, 40 mJ/cm2 and 80 mJ/cm2 doses of UVB were chosen to treat keratinocytes (HaCaT cells). After 24 h of UVB irradiation, 5mC and 5hmC levels were determined by immunohistochemistry (IHC) and immunofluorescence (IF), and at the same time, the expression levels of matrix metalloproteinase 1 (MMP-1) and TETs were assessed by reverse transcription-polymerase chain reaction or Western blot analysis. Results: After 40 mJ/cm2 and 80 mJ/cm2 doses of UVB exposure, both IHC and IF results showed that 5hmC levels increased significantly, while the 5mC levels did not exhibit significant changes in HaCaT cells, compared with HaCat cells without UVB exposure. Moreover, compared with HaCat cells without UVB exposure, the levels of TET1, TET2, and TET3 mRNA and protein expression were significantly upregulated (mRNA: P = 0.0022 and 0.0043 for TET1; all P < 0.0001 for TET2; all P = 0.0006 for TET3; protein: P = 0.0012 and 0.0006 for TET1; all P = 0.0022 for TET2; and all P = 0.0002 for TET3), and the levels of MMP-1 mRNA expression increased dose dependently in 40 mJ/cm2 and 80 mJ/cm2 UVB-irradiated groups. Conclusion: UVB radiation could cause increased 5hmC and TET expression, which might become a novel biomarker in UVB-related skin aging. PMID:28229992

Keeping an eye on the ring: COMS plaque loading optimization for improved dose conformity and homogeneity.

PubMed

Gagne, Nolan L; Cutright, Daniel R; Rivard, Mark J

2012-09-01

To improve tumor dose conformity and homogeneity for COMS plaque brachytherapy by investigating the dosimetric effects of varying component source ring radionuclides and source strengths. The MCNP5 Monte Carlo (MC) radiation transport code was used to simulate plaque heterogeneity-corrected dose distributions for individually-activated source rings of 14, 16 and 18 mm diameter COMS plaques, populated with (103)Pd, (125)I and (131)Cs sources. Ellipsoidal tumors were contoured for each plaque size and MATLAB programming was developed to generate tumor dose distributions for all possible ring weighting and radionuclide permutations for a given plaque size and source strength resolution, assuming a 75 Gy apical prescription dose. These dose distributions were analyzed for conformity and homogeneity and compared to reference dose distributions from uniformly-loaded (125)I plaques. The most conformal and homogeneous dose distributions were reproduced within a reference eye environment to assess organ-at-risk (OAR) doses in the Pinnacle(3) treatment planning system (TPS). The gamma-index analysis method was used to quantitatively compare MC and TPS-generated dose distributions. Concentrating > 97% of the total source strength in a single or pair of central (103)Pd seeds produced the most conformal dose distributions, with tumor basal doses a factor of 2-3 higher and OAR doses a factor of 2-3 lower than those of corresponding uniformly-loaded (125)I plaques. Concentrating 82-86% of the total source strength in peripherally-loaded (131)Cs seeds produced the most homogeneous dose distributions, with tumor basal doses 17-25% lower and OAR doses typically 20% higher than those of corresponding uniformly-loaded (125)I plaques. Gamma-index analysis found > 99% agreement between MC and TPS dose distributions. A method was developed to select intra-plaque ring radionuclide compositions and source strengths to deliver more conformal and homogeneous tumor dose distributions than uniformly-loaded (125)I plaques. This method may support coordinated investigations of an appropriate clinical target for eye plaque brachytherapy.

The mass-action law based algorithms for quantitative econo-green bio-research.

PubMed

Chou, Ting-Chao

2011-05-01

The relationship between dose and effect is not random, but rather governed by the unified theory based on the median-effect equation (MEE) of the mass-action law. Rearrangement of MEE yields the mathematical form of the Michaelis-Menten, Hill, Henderson-Hasselbalch and Scatchard equations of biochemistry and biophysics, and the median-effect plot allows linearization of all dose-effect curves regardless of potency and shape. The "median" is the universal common-link and reference-point for the 1st-order to higher-order dynamics, and from single-entities to multiple-entities and thus, it allows the all for one and one for all unity theory to "integrate" simple and complex systems. Its applications include the construction of a dose-effect curve with a theoretical minimum of only two data points if they are accurately determined; quantification of synergism or antagonism at all dose and effect levels; the low-dose risk assessment for carcinogens, toxic substances or radiation; and the determination of competitiveness and exclusivity for receptor binding. Since the MEE algorithm allows the reduced requirement of the number of data points for small size experimentation, and yields quantitative bioinformatics, it points to the deterministic, efficient, low-cost biomedical research and drug discovery, and ethical planning for clinical trials. It is concluded that the contemporary biomedical sciences would greatly benefit from the mass-action law based "Green Revolution".

Current global and Korean issues in radiation safety of nuclear medicine procedures.

PubMed

Song, H C

2016-06-01

In recent years, the management of patient doses in medical imaging has evolved as concern about radiation exposure has increased. Efforts and techniques to reduce radiation doses are focussed not only on the basis of patient safety, but also on the fundamentals of justification and optimisation in cooperation with international organisations such as the International Commission on Radiological Protection, the International Atomic Energy Agency, and the World Health Organization. The Image Gently campaign in children and Image Wisely campaign in adults to lower radiation doses have been initiated in the USA. The European Association of Nuclear Medicine paediatric dosage card, North American consensus guidelines, and Nuclear Medicine Global Initiative have recommended the activities of radiopharmaceuticals that should be administered in children. Diagnostic reference levels (DRLs), developed predominantly in Europe, may be an important tool to manage patient doses. In Korea, overexposure to radiation, even from the use of medical imaging, has become a public issue, particularly since the accident at the Fukushima nuclear power plant. As a result, the Korean Nuclear Safety and Security Commission revised the technical standards for radiation safety management in medical fields. In parallel, DRLs for nuclear medicine procedures have been collected on a nationwide scale. Notice of total effective dose from positron emission tomography-computed tomography for cancer screening has been mandatory since mid-November 2014. © The International Society for Prosthetics and Orthotics.

Development of a technique and conceptual design of a survey instrument for beta dosimetry in the nuclear power industry

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

Murphy, R.O.

1986-01-01

Before an employee of the nuclear power industry can be assigned to work in an area with radiation hazards, the total dose rate from all radiation present should be known to determine the risk. As the plants age, the level of maintenance has increased and certain tasks have required the workers to be exposed to intense beta radiation fields. Currently available survey instruments do not accurately assess the beta dose or dose rate in many circumstances due to several factors, including the fluctuation of the response of the detector due to the variation in the energy of the beta particlesmore » comprising the radiation field. This research involved developing a technique for calculating the beta dose rate, using the differential energy spectrum and the fluence rate for the beta particles, the fundamental features of the beta radiation. The energy spectrum was used to determine a spectrum weighted average mass stopping power (SWAMPS). The SWAMPS, when multiplied by the fluence rate, gives the energy deposited per unit mass per second, which is the absorbed dose rate for the beta radiation. Reference sources were developed and calibrated using an extrapolation chamber that had, itself, been calibrated using beta sources at the National Bureau of Standards. Different spectrometry systems were tested for applicability to the SWAMPS technique.« less

Potential antianxiety activity of Fumaria indica: A preclinical study

PubMed Central

Singh, Gireesh K.; Chauhan, Sudhir K.; Rai, Geeta; Chatterjee, Shyam S.; Kumar, Vikas

2013-01-01

Background: In the view of diverse CNS modulating properties of Fumaria indica, present study was planned to evaluate its putative anxiolytic activity in behavioural models of rats, followed by elucidation of mechanism of observed activity through biochemical estimations. Materials and Methods: Effects of seven daily 100, 200 and 400 mg/kg oral doses of a Fumaria indica extract (FI) was compared with those of an acute oral dose (5 mg/kg) of lorazepam in a battery of rat models consisting of open-field, elevated plus and zero maze, social interaction, and novelty induced feeding tests. Results: Dose dependant antianxiety effects of FI observed in all tests were qualitatively similar to those of the reference anxiolytic drug. Although FI treatments did not alter the concentrations of noradrenaline and serotonin in hippocampus and hypothalamus, concentrations of both these monoamines were dose dependently elevated in prefrontal cortex of FI treated animals. Flunitrazepam binding in brain frontal cortex was also elevated by the extract. Moreover, higher levels of brain expressions of the cytokines TNF-α, IL-1β, and IL-10 observed in animals with prior experience on elevated plus maze were almost completely reversed by the lowest dose of FI tested in the behavioral models. Conclusion: Taken together, these observations strongly suggest that FI is a functionally novel type of antianxiety agent, and that inhibition of cytokine expressions in the brain could be involved in its mode of action. PMID:23661988

Multicenter field trial on possible health effects of toluene. II. Cross-sectional evaluation of acute low-level exposure.

PubMed

Neubert, D; Gericke, C; Hanke, B; Beckmann, G; Baltes, M M; Kühl, K P; Bochert, G; Hartmann, J

2001-11-15

Data on possible acute effects of today's relevant low-level exposure to toluene are contradictory, and information on possible effects of exposure under occupational conditions is largely lacking. In a controlled, multi-center, blinded field trial, effects possibly associated with acute toluene exposure were evaluated in workers of 12 German rotogravure factories. Medical examinations (inquiries on subjective symptoms, and standard tests of psycho-physiological and psycho-motor functions) were performed on almost 1500 volunteers, of whom 1290 were toluene-exposed (1178 men and 112 women), and about 200 participants served as references (157 men and 37 women), but the main aim of the trial was to reveal dose-response relationships. All volunteers were of the morning work-shift (6 h exposure). Both individual ambient air concentrations (time-weighted average) during the work-shift, as well as blood toluene concentrations after the work-shift were measured. Therefore, the medical data could for the first time be correlated with the actual individual body burden (blood toluene level) at the time of testing. In order to largely exclude confounding by chronic toluene exposure, kinetic measurements as well as the psycho-physiological and psycho-motoric tests were performed before and after the work-shift. Except for minor statistical deviations, neither convincing dose-dependent acute effects could be demonstrated with regression analyses in male volunteers at the exposure levels evaluated, nor were significant differences found when applying group statistics (highly toluene-exposed group versus volunteers with negligible exposure). Due to the rather large number of participants, the predictive power of the study is high, especially when compared with previous publications. In two psycho-physiological tests, a few more female volunteers with quite low toluene body burdens (<340 microg/l blood) showed relatively low scores when compared with participants of the reference group. Although evidence for a medical relevance is meager, the small numbers of participants, in both the exposure and the reference groups, hamper a reliable interpretation of the results concerning exposure levels above 85 microg toluene/l blood, and it is difficult to take confounding factors adequately into account. For the end points evaluated and under occupational conditions, neither blood toluene levels of 850 to 1700 microg/l (in the highest exposure group [EXPO-IV] with 56 participants), as measured 1/2 (+/-1/2) h after the work-shift, nor ambient air concentrations (time-weighted average over 6 h) between 50 and 100 ppm (188-375 mg/m(3)) were convincingly associated with alterations in psycho-physiological and psycho-motoric performances or increased the frequency of subjective complaints in male volunteers. For higher dose ranges of toluene exposure (i.e. >1700 microg toluene/l blood [or >100 ppm in ambient air]), our data set is too small for far reaching conclusions. Our data are insufficient for conclusions on a possibly higher susceptibility to toluene of some female workers. Results of kinetic studies and possible effects of long-term exposure are discussed in two accompanying publications (Neubert et al., 2001; Gericke et al., 2001).

A novel method for patient exit and entrance dose prediction based on water equivalent path length measured with an amorphous silicon electronic portal imaging device.

PubMed

Kavuma, Awusi; Glegg, Martin; Metwaly, Mohamed; Currie, Garry; Elliott, Alex

2010-01-21

In vivo dosimetry is one of the quality assurance tools used in radiotherapy to monitor the dose delivered to the patient. Electronic portal imaging device (EPID) images for a set of solid water phantoms of varying thicknesses were acquired and the data fitted onto a quadratic equation, which relates the reduction in photon beam intensity to the attenuation coefficient and material thickness at a reference condition. The quadratic model is used to convert the measured grey scale value into water equivalent path length (EPL) at each pixel for any material imaged by the detector. For any other non-reference conditions, scatter, field size and MU variation effects on the image were corrected by relative measurements using an ionization chamber and an EPID. The 2D EPL is linked to the percentage exit dose table, for different thicknesses and field sizes, thereby converting the plane pixel values at each point into a 2D dose map. The off-axis ratio is corrected using envelope and boundary profiles generated from the treatment planning system (TPS). The method requires field size, monitor unit and source-to-surface distance (SSD) as clinical input parameters to predict the exit dose, which is then used to determine the entrance dose. The measured pixel dose maps were compared with calculated doses from TPS for both entrance and exit depth of phantom. The gamma index at 3% dose difference (DD) and 3 mm distance to agreement (DTA) resulted in an average of 97% passing for the square fields of 5, 10, 15 and 20 cm. The exit dose EPID dose distributions predicted by the algorithm were in better agreement with TPS-calculated doses than phantom entrance dose distributions.

A novel method for patient exit and entrance dose prediction based on water equivalent path length measured with an amorphous silicon electronic portal imaging device

NASA Astrophysics Data System (ADS)

Kavuma, Awusi; Glegg, Martin; Metwaly, Mohamed; Currie, Garry; Elliott, Alex

2010-01-01

In vivo dosimetry is one of the quality assurance tools used in radiotherapy to monitor the dose delivered to the patient. Electronic portal imaging device (EPID) images for a set of solid water phantoms of varying thicknesses were acquired and the data fitted onto a quadratic equation, which relates the reduction in photon beam intensity to the attenuation coefficient and material thickness at a reference condition. The quadratic model is used to convert the measured grey scale value into water equivalent path length (EPL) at each pixel for any material imaged by the detector. For any other non-reference conditions, scatter, field size and MU variation effects on the image were corrected by relative measurements using an ionization chamber and an EPID. The 2D EPL is linked to the percentage exit dose table, for different thicknesses and field sizes, thereby converting the plane pixel values at each point into a 2D dose map. The off-axis ratio is corrected using envelope and boundary profiles generated from the treatment planning system (TPS). The method requires field size, monitor unit and source-to-surface distance (SSD) as clinical input parameters to predict the exit dose, which is then used to determine the entrance dose. The measured pixel dose maps were compared with calculated doses from TPS for both entrance and exit depth of phantom. The gamma index at 3% dose difference (DD) and 3 mm distance to agreement (DTA) resulted in an average of 97% passing for the square fields of 5, 10, 15 and 20 cm. The exit dose EPID dose distributions predicted by the algorithm were in better agreement with TPS-calculated doses than phantom entrance dose distributions.

Monte Carlo evaluation of magnetically focused proton beams for radiosurgery

NASA Astrophysics Data System (ADS)

McAuley, Grant A.; Heczko, Sarah L.; Nguyen, Theodore T.; Slater, James M.; Slater, Jerry D.; Wroe, Andrew J.

2018-03-01

The purpose of this project is to investigate the advantages in dose distribution and delivery of proton beams focused by a triplet of quadrupole magnets in the context of potential radiosurgery treatments. Monte Carlo simulations were performed using various configurations of three quadrupole magnets located immediately upstream of a water phantom. Magnet parameters were selected to match what can be commercially manufactured as assemblies of rare-earth permanent magnetic materials. Focused unmodulated proton beams with a range of ~10 cm in water were target matched with passive collimated beams (the current beam delivery method for proton radiosurgery) and properties of transverse dose, depth dose and volumetric dose distributions were compared. Magnetically focused beams delivered beam spots of low eccentricity to Bragg peak depth with full widths at the 90% reference dose contour from ~2.5 to 5 mm. When focused initial beam diameters were larger than matching unfocused beams (10 of 11 cases) the focused beams showed 16%–83% larger peak-to-entrance dose ratios and 1.3 to 3.4-fold increases in dose delivery efficiency. Peak-to-entrance and efficiency benefits tended to increase with larger magnet gradients and larger initial diameter focused beams. Finally, it was observed that focusing tended to shift dose in the water phantom volume from the 80%–20% dose range to below 20% of reference dose, compared to unfocused beams. We conclude that focusing proton beams immediately upstream from tissue entry using permanent magnet assemblies can produce beams with larger peak-to-entrance dose ratios and increased dose delivery efficiencies. Such beams could potentially be used in the clinic to irradiate small-field radiosurgical targets with fewer beams, lower entrance dose and shorter treatment times.

Results of a 2011 national questionnaire for investigation of mean glandular dose from mammography in Japan.

PubMed

Asada, Y; Suzuki, S; Minami, K; Shirakawa, S

2014-03-01

Diagnostic reference levels (DRLs) for mammography have yet to be created in Japan. A national questionnaire investigation into radiographic conditions in Japan was carried out for the purpose of creating DRLs. Items investigated included the following: tube voltage; tube current; current-time product; source-image distance; craniocaudal view; automatic exposure control (AEC) settings; name of mammography unit; image receptor system (computed radiography (CR), flat panel detector (FPD), or film/screen (F/S)); and supported or unsupported monitor diagnosis (including monitor resolution). Estimation of the mean glandular dose (MGD) for mammography was performed and compared with previous investigations. The MGD was 1.58(0.48) mGy, which did not significantly differ from a 2007 investigation. In relation to image receptors, although no difference in average MGD values was observed between CR and FPD systems, F/S systems had a significantly decreased value compared to both CR and FPDs. Concerning digital systems (FPDs), the MGD value of the direct conversion system was significantly higher than the indirect conversion system. No significant difference in MGD value was evident concerning type of monitor diagnosis for either the CR or the FPD digital systems; however, hard copies were used more often in CR. No significant difference in the MGD value was found in relation to monitor resolution. This report suggests ways to lower the doses patients undergoing mammography receive in Japan, and serves as reference data for 4.2 cm compressed breast tissue of 50% composition DRLs. Furthermore, our findings suggest that further optimisation of FPD settings can promote a reduction in the MGD value.

Using a single tablet daily to treat latent tuberculosis infection in Brazil: bioequivalence of two different isoniazid formulations (300 mg and 100 mg) demonstrated by a sensitive and rapid high-performance liquid chromatography-tandem mass spectrometry method in a randomised, crossover study.

PubMed

Daher, André; Pitta, Luciana; Santos, Tereza; Barreira, Draurio; Pinto, Douglas

2015-06-01

The recommended treatment for latent tuberculosis (TB) infection in adults is a daily dose of isoniazid (INH) 300 mg for six months. In Brazil, INH was formulated as 100 mg tablets. The treatment duration and the high pill burden compromised patient adherence to the treatment. The Brazilian National Programme for Tuberculosis requested a new 300 mg INH formulation. The aim of our study was to compare the bioavailability of the new INH 300 mg formulation and three 100 mg tablets of the reference formulation. We conducted a randomised, single dose, open label, two-phase crossover bioequivalence study in 28 healthy human volunteers. The 90% confidence interval for the INH maximum concentration of drug observed in plasma and area under the plasma concentration vs. time curve from time zero to the last measurable concentration "time t" was 89.61-115.92 and 94.82-119.44, respectively. The main limitation of our study was that neither adherence nor the safety profile of multiple doses was evaluated. To determine the level of INH in human plasma, we developed and validated a sensitive, simple and rapid high-performance liquid chromatography-tandem mass spectrometry method. Our results showed that the new formulation was bioequivalent to the 100 mg reference product. This finding supports the use of a single 300 mg tablet daily strategy to treat latent TB. This new formulation may increase patients' adherence to the treatment and quality of life.

Characterization of a synthetic single crystal diamond Schottky diode for radiotherapy electron beam dosimetry.

PubMed

Di Venanzio, C; Marinelli, Marco; Milani, E; Prestopino, G; Verona, C; Verona-Rinati, G; Falco, M D; Bagalà, P; Santoni, R; Pimpinella, M

2013-02-01

To investigate the dosimetric properties of synthetic single crystal diamond based Schottky diodes under irradiation with therapeutic electron beams from linear accelerators. A single crystal diamond detector was fabricated and tested under 6, 8, 10, 12, and 15 MeV electron beams. The detector performances were evaluated using three types of commercial detectors as reference dosimeters: an Advanced Markus plane parallel ionization chamber, a Semiflex cylindrical ionization chamber, and a p-type silicon detector. Preirradiation, linearity with dose, dose rate dependence, output factors, lateral field profiles, and percentage depth dose profiles were investigated and discussed. During preirradiation the diamond detector signal shows a weak decrease within 0.7% with respect to the plateau value and a final signal stability of 0.1% (1σ) is observed after about 5 Gy. A good linear behavior of the detector response as a function of the delivered dose is observed with deviations below ±0.3% in the dose range from 0.02 to 10 Gy. In addition, the detector response is dose rate independent, with deviations below 0.3% in the investigated dose rate range from 0.17 to 5.45 Gy∕min. Percentage depth dose curves obtained from the diamond detector are in good agreement with the ones from the reference dosimeters. Lateral beam profile measurements show an overall good agreement among detectors, taking into account their respective geometrical features. The spatial resolution of solid state detectors is confirmed to be better than that of ionization chambers, being the one from the diamond detector comparable to that of the silicon diode. A good agreement within experimental uncertainties was also found in terms of output factor measurements between the diamond detector and reference dosimeters. The observed dosimetric properties indicate that the tested diamond detector is a suitable candidate for clinical electron beam dosimetry.

A global quality assurance system for personalized radiation therapy treatment planning for the prostate (or other sites)

NASA Astrophysics Data System (ADS)

Nwankwo, Obioma; Sihono, Dwi Seno K.; Schneider, Frank; Wenz, Frederik

2014-09-01

Introduction: the quality of radiotherapy treatment plans varies across institutions and depends on the experience of the planner. For the purpose of intra- and inter-institutional homogenization of treatment plan quality, we present an algorithm that learns the organs-at-risk (OARs) sparing patterns from a database of high quality plans. Thereafter, the algorithm predicts the dose that similar organs will receive in future radiotherapy plans prior to treatment planning on the basis of the anatomies of the organs. The predicted dose provides the basis for the individualized specification of planning objectives, and for the objective assessment of the quality of radiotherapy plans. Materials and method: one hundred and twenty eight (128) Volumetric Modulated Arc Therapy (VMAT) plans were selected from a database of prostate cancer plans. The plans were divided into two groups, namely a training set that is made up of 95 plans and a validation set that consists of 33 plans. A multivariate analysis technique was used to determine the relationships between the positions of voxels and their dose. This information was used to predict the likely sparing of the OARs of the plans of the validation set. The predicted doses were visually and quantitatively compared to the reference data using dose volume histograms, the 3D dose distribution, and a novel evaluation metric that is based on the dose different test. Results: a voxel of the bladder on the average receives a higher dose than a voxel of the rectum in optimized radiotherapy plans for the treatment of prostate cancer in our institution if both voxels are at the same distance to the PTV. Based on our evaluation metric, the predicted and reference dose to the bladder agree to within 5% of the prescribed dose to the PTV in 18 out of 33 cases, while the predicted and reference doses to the rectum agree to within 5% in 28 out of the 33 plans of the validation set. Conclusion: We have described a method to predict the likely dose that OARs will receive before treatment planning. This prospective knowledge could be used to implement a global quality assurance system for personalized radiation therapy treatment planning.

Relative bioavailability of two 5-mg montelukast sodium chewable tablets: a single dose, randomized, open-label, 2-period crossover comparison in healthy korean adult male volunteers.

PubMed

Kim, H T; Song, Y-K; Lee, S D; Park, Y; Kim, C-K

2012-03-01

Montelukast sodium, cysteinyl leukotriene receptor 1 specific antagonist, has been marketed in Korea for the treatment of bronchial asthma and allergic rhinitis. The aim of this study was to compare the pharmacokinetics and relative bioavailability of a test and reference formulation of montelukast 5-mg chewable tablets in healthy Korean male volunteers to meet KFDA regulatory criteria for marketing of the new generic formulation. This study was designed as a single-dose, 2-treatment, and 2-period crossover trial with 32 healthy volunteers. Each subject was randomly assigned to receive the test (Dong-Kook Montelukast Sodium Chewable Tablet 5 mg®) or reference (Singulair Chewable Tablet 5 mg®) formulation. The tablet was chewed 20 times, and then swallowed with 240 mL of water. Plasma concentrations of montelukast up to 24 h after the dose were determined using a validated UPLC-MS/MS method, and the bioequivalence between the 2 formulations was assessed by statistical analysis of mean ratios of log-transformed AUC0-24 h and Cmax. No period or sequence effects were detected. The AUC0-24 h was 1 835 ng·h/mL for the test formulation, and 1 930 ng·h/mL for the reference formulation. The respective values of AUC0-∞ were 1 917 and 2 015 ng·h/mL. The Cmax of the test and reference products (247 and 283 ng/mL, respectively) reached at 2.25 and 2.72 h, respectively. Then, they gradually decreased with the mean terminal t1/2 of 5.25 and 5.30 h for the test and reference products, respectively. The 90% CIs for the ratio of log-transformed AUC0-24 h and Cmax for the test and reference formulations were 0.92-0.99 and 0.83-0.91, respectively. No adverse events were reported in this study. This single dose study found that the test and reference products met the regulatory criteria for bioequivalence in these fasting healthy Korean male volunteers. © Georg Thieme Verlag KG Stuttgart · New York.

Effect of hydro-alcoholic extract of Vernonia cinerea Less. against ethylene glycol-induced urolithiasis in rats.

PubMed

Hiremath, Ravindra D; Jalalpure, Sunil S

2016-01-01

Aim of this study is to evaluate antiurolithiatic potential of whole plant hydro-alcoholic (30:70) extract of Vernonia cinerea Less. in accordance to its claims made in ancient literature and also being one of the ingredients of cystone, a marketed formulation widely used in the management of urolithiasis. To induce urolithiasis, 0.75% v/v ethylene glycol was administered orally for 14 days. The curative dose of 400 mg/kg b.w. and preventive doses of 100, 200, and 400 mg/kg b.w. were administered from 15 th to 28 th and 1 st to 28 days, respectively. Cystone 750 mg/kg b.w. was selected as the reference standard for both curative and preventive doses. On 28 th day, urinate of 24 h was collected and subjected for estimation of calcium, oxalate, and phosphates. Serum biochemical and kidney homogenate analysis was done for determination of renal oxalate contents. The diseased Group II showed marked increase ( P < 0.001 vs. normal Group I) in levels of urine calcium, oxalate, and phosphate. Serum creatinine, urea, and uric acid levels were also increased. Histopathological studies of kidney sections revealed significant changes. Treatment with hydro-alcoholic extract of V. cinerea showed significant ( P < 0.01 vs. calculi-induced Group II) dose-dependent activity. A progressive increase in urine output, body weight, and decline in concentrations of stone-forming components such as calcium, oxalates, and phosphates was observed. It can be inferred that V. cinerea Less. is effective in ethylene glycol-induced urolithiasis and may have a potential in preventing and curing urolithiasis.

Thalidomide results in diminished ovarian reserve in reproductive age female IBD patients

PubMed Central

Peng, Xiang; Zhi, Min; Wei, Ming; Li, Ting-Ting; Zhang, Min; Zhang, Yuan-Qi; He, Huan; Su, Mingli; Wang, Wei; Chen, Jun-rong; Tang, Jian; Gao, Xiang; Hu, Pin-Jin; Liang, Xiao-Yan

2017-01-01

Abstract The effectiveness of thalidomide in treating inflammatory bowel disease (IBD) has been widely recognized. Meanwhile, many serious adverse drug reactions have been observed, but no know reports on ovarian reserve function. Female patients, ranging in age between 18 and 40, were referred to our institution to undergo sex hormone detection and ultrasonic scanning for ovarian function assessment, between February 1, 2016 and September 31, 2016. Thirty-three patients treated with thalidomide (group A), 73 patients without thalidomide (group B), and 78 healthy women as control were studied. Menstrual disorder was higher in group A than group B (78.8% vs 57.2%, P < 0.05), and both groups were higher than control group 33.3%, P < 0.05. Anti-Mullerian hormone (AMH) levels and antral follicle count (AFC) in group A were lower than group B, P < 0.05, while estradiol (E2) and follicle-stimulating hormone (FSH) levels were no different between 2 groups. Crohn Disease Endoscopic Index of Severity (CDEIS) and thalidomide were the independent risk factors in diminished ovarian reserve (DOR), and when dose reached 75 mg/day, 5 g total, or when treatment time reached 10 months respectively. These influence may increasing (P < 0.05), but they may recover after stopping (P < 0.05). Thalidomide was an independent risk factor leading to DOR in female IBD patients, the influence may increasing when daily dose and accumulated dose reached 75 mg/day and 5 g total dose, but may be reversed by stopping. PMID:28538364

Diagnostic reference levels in low- and middle-income countries: early "ALARAm" bells?

PubMed

Meyer, Steven; Groenewald, Willem A; Pitcher, Richard D

2017-04-01

Background In 1996 the International Commission on Radiological Protection (ICRP) introduced diagnostic reference levels (DRLs) as a quality assurance tool for radiation dose optimization. While many countries have published DRLs, available data are largely from high-income countries. There is arguably a greater need for DRLs in low- and middle-income-countries (LMICs), where imaging equipment may be older and trained imaging technicians are scarce. To date, there has been no critical analysis of the published work on DRLs in LMICs. Such work is important to evaluate data deficiencies and stimulate future quality assurance initiatives. Purpose To review the published work on DRLs in LMICs and to critically analyze the comprehensiveness of available data. Material and Methods Medline, Scopus, and Web of Science database searches were conducted for English-language articles published between 1996 and 2015 documenting DRLs for diagnostic imaging in LMICs. Retrieved articles were analyzed and classified by geographical region, country of origin, contributing author, year of publication, imaging modality, body part, and patient age. Results Fifty-three articles reported DRLs for 28 of 135 LMICs (21%), reflecting data from 26/104 (25%) middle-income countries and 2/31 (6%) low-income countries. General radiography (n = 26, 49%) and computerized tomography (n = 17, 32%) data were most commonly reported. Pediatric DRLs (n = 14, 26%) constituted approximately one-quarter of published work. Conclusion Published DRL data are deficient in the majority of LMICs, with the paucity most striking in low-income countries. DRL initiatives are required in LMICs to enhance dose optimization.

Derivation of new diagnostic reference levels for neuro-paediatric computed tomography examinations in Switzerland.

PubMed

Wagner, Franca; Bize, Julie; Racine, Damien; Le Coultre, Regis; Francis, Verdun; Trueb, Philipp; Treier, Reto

2018-05-22

Definition of new national diagnostic reference levels (DRLs) for volume computed tomography dose index (CTDIvol) and dose length product (DLP) for neuro-paediatric CT examinations depending on the medical indication. Methods: Paediatric cranial CT data sets acquired between January 2013 and December 2016 were retrospectively collected between July 2016 and March 2017 from the eight largest university and cantonal hospitals that perform most of the neuro-paediatric CTs in Switzerland. A consensus review of CTDIvol and DLP was undertaken for the three defined anatomical regions: brain, facial bone and petrous bone; each with and without contrast medium application. All indications for cranial CT imaging in paediatrics were assigned to one of these three regions. Descriptive statistical analysis of the distribution of the median values for CTDIvol and DLP yielded minimum, maximum, 25th percentile (1st quartile), median (2nd quartile) and 75th percentile (3rd quartile). New DRLs for neuro-paediatric CT examinations in Switzerland were based on the 75th percentiles of the distributions of the median values of all eight centres. Where appropriate, values were rounded such that the DRLs increase or at least remain constant as the age of the patient increases. Results: Our results revealed DRLs for CTDIvol and DLP up to 20% lower than the DRLs used so far in Switzerland and elsewhere in Europe. Conclusions: This study provides Swiss neuro-paediatric CT DRL values to establish optimum conditions for paediatric cranial CT examinations. Periodic national updates of DRLs, following international comparisons, are essential. . Creative Commons Attribution license.

The development of Operational Intervention Levels (OILs) for Soils - A decision support tool in nuclear and radiological emergency response

NASA Astrophysics Data System (ADS)

Lee Zhi Yi, Amelia; Dercon, Gerd; Blackburn, Carl; Kheng, Heng Lee

2017-04-01

In the event of a large-scale nuclear accident, the swift implementation of response actions is imperative. For food and agriculture, it is important to restrict contaminated food from being produced or gathered, and to put in place systems to prevent contaminated produce from entering the food chain. Emergency tools and response protocols exist to assist food control and health authorities but they tend to focus on radioactivity concentrations in food products as a means of restricting the distribution and sale of contaminated produce. Few, if any, emergency tools or protocols focus on the food production environment, for example radioactivity concentrations in soils. Here we present the Operational Intervention Levels for Soils (OIL for Soils) concept, an optimization tool developed at the IAEA to facilitate agricultural decision making and to improve nuclear emergency preparedness and response capabilities. Effective intervention relies on the prompt availability of radioactivity concentration data and the ability to implement countermeasures. Sampling in food and agriculture can be demanding because it may involve large areas and many sample types. In addition, there are finite resources available in terms of manpower and laboratory support. Consequently, there is a risk that timely decision making will be hindered and food safety compromised due to time taken to sample and analyse produce. However, the OILs for Soils concept developed based on experience in Japan can help in this situation and greatly assist authorities responsible for agricultural production. OILs for Soils - pre-determined reference levels of air dose rates linked to radionuclide concentrations in soils - can be used to trigger response actions particularly important for agricultural and food protection. Key considerations in the development of the OILs for Soils are: (1) establishing a pragmatic sampling approach to prioritize and optimize available resources and data requirements for decision making in agricultural sites: (2) creating a system that is adaptable to different countries, and; (3) developing a framework to calculate default values of OILs for Soils for application during an emergency. The OILs for Soils reference levels are calculated using a mathematical model. Empirical equations, paired with radionuclide data (e.g. Cs-134, Cs-137 and I-131) from the ICRU 53 report, are utilized to determine soil contamination from aerial monitoring air dose rate data. Modelling allows soil contamination values to be readily approximated and this is used to prioritize soil and food sampling sites. Reference levels are based on a model that considers radionuclide transfer factors for up-take into plants, soil density, and soil sampling depth. Decision actions for determined reference levels are suggested for processed foods, animal products, animal feed and crop products (including plants at the growing stage, mature stage, fallow farmland, and forestry products). With these steps, OILs for Soils provide practical guidance that will equip authorities to respond efficiently and help maintain the safety of the food supply during large-scale nuclear or radiological emergency situations.

Repeated Post- or Presession Cocaine Administration: Roles of Dose and Fixed-Ratio Schedule

ERIC Educational Resources Information Center

Pinkston, Jonathan W.; Branch, Marc N.

2004-01-01

Effects of repeated administration of cocaine to animals behaving under operant contingencies have depended on when the drug is given. Moderate doses given presession have generally led to a decrease in the drug's effect, an outcome usually referred to as tolerance. When these same doses have been given after sessions, the usual result has been no…

Radiation dose in temporomandibular joint zonography

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

Coucke, M.E.; Bourgoignie, R.R.; Dermaut, L.R.

1991-06-01

Temporomandibular joint morphology and function can be evaluated by panoramic zonography. Thermoluminescent dosimetry was applied to evaluate the radiation dose to predetermined sites on a phantom eye, thyroid, pituitary, and parotid, and the dose distribution on the skin of the head and neck when the TMJ program of the Zonarc panoramic x-ray unit was used. Findings are discussed with reference to similar radiographic techniques.

Dose calculation algorithm of fast fine-heterogeneity correction for heavy charged particle radiotherapy.

PubMed

Kanematsu, Nobuyuki

2011-04-01

This work addresses computing techniques for dose calculations in treatment planning with proton and ion beams, based on an efficient kernel-convolution method referred to as grid-dose spreading (GDS) and accurate heterogeneity-correction method referred to as Gaussian beam splitting. The original GDS algorithm suffered from distortion of dose distribution for beams tilted with respect to the dose-grid axes. Use of intermediate grids normal to the beam field has solved the beam-tilting distortion. Interplay of arrangement between beams and grids was found as another intrinsic source of artifact. Inclusion of rectangular-kernel convolution in beam transport, to share the beam contribution among the nearest grids in a regulatory manner, has solved the interplay problem. This algorithmic framework was applied to a tilted proton pencil beam and a broad carbon-ion beam. In these cases, while the elementary pencil beams individually split into several tens, the calculation time increased only by several times with the GDS algorithm. The GDS and beam-splitting methods will complementarily enable accurate and efficient dose calculations for radiotherapy with protons and ions. Copyright © 2010 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

Meta-analysis of the Association Between the Level of Cannabis Use and Risk of Psychosis.

PubMed

Marconi, Arianna; Di Forti, Marta; Lewis, Cathryn M; Murray, Robin M; Vassos, Evangelos

2016-09-01

Cannabis use has been reported to induce long-lasting psychotic disorders and a dose-response relationship has been observed. We performed a systematic review of studies that investigate the association between the degree of cannabis consumption and psychosis and a meta-analysis to quantify the magnitude of effect. Published studies were identified through search of electronic databases, supplemented by manual searches of bibliographies. Studies were considered if they provided data on cannabis consumption prior to the onset of psychosis using a dose criterion (frequency/amount used) and reported psychosis-related outcomes. We performed random effects meta-analysis of individual data points generated with a simulation method from the summary data of the original studies. From 571 references, 18 studies fulfilled inclusion criteria for the systematic review and 10 were inserted in the meta-analysis, enrolling a total of 66 816 individuals. Higher levels of cannabis use were associated with increased risk for psychosis in all the included studies. A logistic regression model gave an OR of 3.90 (95% CI 2.84 to 5.34) for the risk of schizophrenia and other psychosis-related outcomes among the heaviest cannabis users compared to the nonusers. Current evidence shows that high levels of cannabis use increase the risk of psychotic outcomes and confirms a dose-response relationship between the level of use and the risk for psychosis. Although a causal link cannot be unequivocally established, there is sufficient evidence to justify harm reduction prevention programs. © The Author 2016. Published by Oxford University Press on behalf of the Maryland Psychiatric Research Center. All rights reserved. For permissions, please email: journals.permissions@oup.com.

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

Hull, A.P.

From the major accident at Unit 4 of the Chernobyl nuclear power station, a plume of airborne radioactive fission products was initially carried northwesterly toward Poland, thence toward Scandinavia and into Central Europe. Reports of the levels of radioactivity in a variety of media and of external radiation levels were collected in the Department of Energy's Emergency Operations Center and compiled into a data bank. Portions of these and other data which were obtained directly from published and official reports were utilized to make a preliminary assessment of the extent and magnitude of the external dose to individuals downwind frommore » Chernobyl. Radioactive /sup 131/I was the predominant fission product. The time of arrival of the plume and the maximum concentrations of /sup 131/I in air, vegetation and milk and the maximum reported depositions and external radiation levels have been tabulated country by country. A large amount of the total activity in the release was apparently carried to a significant elevation. The data suggest that in areas where rainfall occurred, deposition levels were from ten to one-hundred times those observed in nearby ''dry'' locations. Sufficient spectral data were obtained to establish average release fractions and to establish a reference spectra of the other nuclides in the release. Preliminary calculations indicated that the collective dose equivalent to the population in Scandinavia and Central Europe during the first year after the Chernobyl accident would be about 8 x 10/sup 6/ person-rem. From the Soviet report, it appears that a first year population dose of about 2 x 10/sup 7/ person-rem (2 x 10/sup 5/ Sv) will be received by the population who were downwind of Chernobyl within the U.S.S.R. during the accident and its subsequent releases over the following week. 32 refs., 14 figs., 20 tabs.« less

Development of a four-dimensional Monte Carlo dose calculation system for real-time tumor-tracking irradiation with a gimbaled X-ray head.

PubMed

Ishihara, Yoshitomo; Nakamura, Mitsuhiro; Miyabe, Yuki; Mukumoto, Nobutaka; Matsuo, Yukinori; Sawada, Akira; Kokubo, Masaki; Mizowaki, Takashi; Hiraoka, Masahiro

2017-03-01

To develop a four-dimensional (4D) dose calculation system for real-time tumor tracking (RTTT) irradiation by the Vero4DRT. First, a 6-MV photon beam delivered by the Vero4DRT was simulated using EGSnrc. A moving phantom position was directly measured by a laser displacement gauge. The pan and tilt angles, monitor units, and the indexing time indicating the phantom position were also extracted from a log file. Next, phase space data at any angle were created from both the log file and particle data under the dynamic multileaf collimator. Irradiation both with and without RTTT, with the phantom moving, were simulated using several treatment field sizes. Each was compared with the corresponding measurement using films. Finally, dose calculation for each computed tomography dataset of 10 respiratory phases with the X-ray head rotated was performed to simulate the RTTT irradiation (4D plan) for lung, liver, and pancreatic cancer patients. Dose-volume histograms of the 4D plan were compared with those calculated on the single reference respiratory phase without the gimbal rotation [three-dimensional (3D) plan]. Differences between the simulated and measured doses were less than 3% for RTTT irradiation in most areas, except the high-dose gradient. For clinical cases, the target coverage in 4D plans was almost identical to that of the 3D plans. However, the doses to organs at risk in the 4D plans varied at intermediate- and low-dose levels. Our proposed system has acceptable accuracy for RTTT irradiation in the Vero4DRT and is capable of simulating clinical RTTT plans. Copyright © 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

Radiation dose reduction in parasinus CT by spectral shaping.

PubMed

May, Matthias S; Brand, Michael; Lell, Michael M; Sedlmair, Martin; Allmendinger, Thomas; Uder, Michael; Wuest, Wolfgang

2017-02-01

Spectral shaping aims to narrow the X-ray spectrum of clinical CT. The aim of this study was to determine the image quality and the extent of radiation dose reduction that can be achieved by tin prefiltration for parasinus CT. All scans were performed with a third generation dual-source CT scanner. A study protocol was designed using 100 kV tube voltage with tin prefiltration (200 mAs) that provides image noise levels comparable to a low-dose reference protocol using 100 kV without spectral shaping (25 mAs). One hundred consecutive patients were prospectively enrolled and randomly assigned to the study or control group. All patients signed written informed consent. The study protocol was approved by the local Institutional Review Board and applies to the HIPAA. Subjective and objective image quality (attenuation values, image noise, and contrast-to-noise ratio (CNR)) were assessed. Radiation exposure was assessed as volumetric CT dose index, and effective dose was estimated. Mann-Whitney U test was performed for radiation exposure and for image noise comparison. All scans were of diagnostic image quality. Image noise in air, in the retrobulbar fat, and in the eye globe was comparable between both groups (all p > 0.05). CNR eye globe/air did not differ significantly between both groups (p = 0.7). Radiation exposure (1.7 vs. 2.1 mGy, p < 0.01) and effective dose (0.055 vs. 0.066 mSv, p < 0.01) were significantly reduced in the study group. Radiation dose can be further reduced by 17% for low-dose parasinus CT by tin prefiltration maintaining diagnostic image quality.

Effects of particle size and coating on toxicologic parameters, fecal elimination kinetics and tissue distribution of acutely ingested silver nanoparticles in a mouse model

PubMed Central

Bergin, Ingrid L.; Wilding, Laura A.; Morishita, Masako; Walacavage, Kim; Ault, Andrew P.; Axson, Jessica L.; Stark, Diana I.; Hashway, Sara A.; Capracotta, Sonja S.; Leroueil, Pascale R.; Maynard, Andrew D.; Philbert, Martin A.

2015-01-01

Consumer exposure to silver nanoparticles (AgNP) via ingestion can occur due to incorporation of AgNP into products such as food containers and dietary supplements. AgNP variations in size and coating may affect toxicity, elimination kinetics or tissue distribution. Here, we directly compared acute administration of AgNP of two differing coatings and sizes to mice, using doses of 0.1, 1 and 10 mg/kg body weight/day administered by oral gavage for 3 days. The maximal dose is equivalent to 2000× the EPA oral reference dose. Silver acetate at the same doses was used as ionic silver control. We found no toxicity and no significant tissue accumulation. Additionally, no toxicity was seen when AgNP were dosed concurrently with a broad-spectrum antibiotic. Between 70.5% and 98.6% of the administered silver dose was recovered in feces and particle size and coating differences did not significantly influence fecal silver. Peak fecal silver was detected between 6- and 9-h post-administration and <0.5% of the administered dose was cumulatively detected in liver, spleen, intestines or urine at 48 h. Although particle size and coating did not affect tissue accumulation, silver was detected in liver, spleen and kidney of mice administered ionic silver at marginally higher levels than those administered AgNP, suggesting that silver ion may be more bioavailable. Our results suggest that, irrespective of particle size and coating, acute oral exposure to AgNP at doses relevant to potential human exposure is associated with predominantly fecal elimination and is not associated with accumulation in tissue or toxicity. PMID:26305411

Radiation dose from MDCT using Monte Carlo simulations: estimating fetal dose due to pulmonary embolism scans accounting for overscan

NASA Astrophysics Data System (ADS)

Angel, E.; Wellnitz, C.; Goodsitt, M.; DeMarco, J.; Cagnon, C.; Ghatali, M.; Cody, D.; Stevens, D.; McCollough, C.; Primak, A.; McNitt-Gray, M.

2007-03-01

Pregnant women with shortness of breath are increasingly referred for CT Angiography to rule out Pulmonary Embolism (PE). While this exam is typically focused on the lungs, extending scan boundaries and overscan can add to the irradiated volume and have implications on fetal dose. The purpose of this work was to estimate radiation dose to the fetus when various levels of overscan were encountered. Two voxelized models of pregnant patients derived from actual patient anatomy were created based on image data. The models represent an early (< 7 weeks) and late term pregnancy (36 weeks). A previously validated Monte Carlo model of an MDCT scanner was used that takes into account physical details of the scanner. Simulated helical scans used 120 kVp, 4x5 mm beam collimation, pitch 1, and varying beam-off locations (edge of the irradiated volume) were used to represent different protocols plus overscan. Normalized dose (mGy/100mAs) was calculated for each fetus. For the early term and the late term pregnancy models, fetal dose estimates for a standard thoracic PE exam were estimated to be 0.05 and 0.3 mGy/100mAs, respectively, increasing to 9 mGy/100mAs when the beam-off location was extended to encompass the fetus. When performing PE exams to rule out PE in pregnant patients, the beam-off location may have a large effect on fetal dose, especially for late term pregnancies. Careful consideration of ending location of the x-ray beam - and not the end of image data - could result in significant reduction in radiation dose to the fetus.

Reproductive Alterations in Chronically Exposed Female Mice to Environmentally Relevant Doses of a Mixture of Phthalates and Alkylphenols.

PubMed

Patiño-García, Daniel; Cruz-Fernandes, Leonor; Buñay, Julio; Palomino, Jaime; Moreno, Ricardo D

2018-02-01

Endocrine-disrupting chemicals (EDCs) are exogenous compounds that modify hormone biosynthesis, causing adverse effects to human health. Among them, phthalates and alkylphenols are important due to their wide use in plastics, detergents, personal care products, cosmetics, and food packaging. However, their conjoint effects over reproductive female health have not been addressed. The aim of this work was to test the effect of chronically exposed female mice to a mixture of three phthalates [bis (2-ethylhexyl), dibutyl, and benzyl butyl] and two alkylphenols (4-nonylphenol and 4-tert-octylphenol) from conception to adulthood at environmentally relevant doses. These EDCs were administered in two doses: one below the minimal risk dose to cause adverse effects on human development and reproduction [1 mg/kg body weight (BW)/d of the total mixture] and the other one based on the reference value close to occupational exposure in humans (10 mg/kg BW/d of the total mixture). Our results show that both doses had similar effects regarding the uterus and ovary relative weight, estrous cyclicity, serum levels of progesterone and 17β-estradiol, and expression of key elements in the steroidogenesis pathway (acute steroidogenic regulatory protein and CYP19A1). However, only the 1-mg/kg BW/d dose delayed the onset of puberty and the transition from preantral to antral follicles, whereas the 10-mg/kg BW/d dose decreased the number of antral follicles and gonadotropin receptor expression. In addition, we observed changes in several fertility parameters in exposed females and in their progeny (F2 generation). In conclusion, our results indicate that chronic exposure to a complex EDC mixture, at environmentally relevant doses, modifies reproductive parameters in female mice. Copyright © 2018 Endocrine Society.

IRIS Toxicological Review of Dichloromethane (Methylene ...

EPA Pesticide Factsheets

EPA has finalized the Toxicological Review of Dichloromethane (Methylene Chloride): In support of the Integrated Risk Information System (IRIS). Now final, this assessment may be used by EPA’s program and regional offices to inform decisions to protect human health. This document presents background information and justification for the Intergrated Risk Information System (IRIS) Summary of the hazard and dose-response assessment of dichloromethane. IRIS Summaries may include oral reference dose (RfD) and inhalation reference concentration (RfC) values for chronic and other exposure durations, and a carcinogencity assessment. Internet/NCEA web site

Reference dose (RfD): description and use in health risk assessments

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

Barnes, D.G.; Dourson, M.

1988-12-01

For many years the concept of the acceptable daily intake has served the toxicological and regulatory fields quite well. However, as approaches to assessing the health significance of exposures to noncarcinogenic substances receive greater scrutiny, some difficulties with this traditional approach have become more apparent. Consequently, the concept of the reference dose is introduced in order to avoid use of prejudicial terms (e.g., safety and acceptable), to promote greater consistency in the assessment of noncarcinogenic chemicals, and to maintain the functional separation between risk assessment and risk management.

Effects of prolonged daily low level mercuric chloride dosing in a horse

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

Roberts, M.C.; Seawright, A.A.

1978-12-01

Relatively few of the signs hitherto accepted as being consistent with chronic inorganic mercury intoxication were exhibited by a horse exposed to 31.3 g inorganic mercury (dose rate 0.4 mg/kg) given as mercuric chloride over 23.5 weeks. Clinical features included poor appetite, weight loss, debility, dullness, transient diarrhea and polydipsia, with little impairment of functional renal capacity. Limited degenerative changes were seen in the renal tubules. Edema and a mild inflammatory infiltrate of predominantly the mucosa and submucosa caused marked thickening of the lower alimentary tract. An approximate mean plasma inorganic mercury concentration of 400 ng/ml was quickly reached andmore » maintained. The kidneys had the highest tissue mercury content, almost 10 times greater than the liver and over 70 times that found in the intestinal mucosa and the dorsal root ganglia. 18 references, 6 figures.« less

Dosimetry of Al2O3 optically stimulated luminescent dosimeter at high energy photons and electrons

NASA Astrophysics Data System (ADS)

Yusof, M. F. Mohd; Joohari, N. A.; Abdullah, R.; Shukor, N. S. Abd; Kadir, A. B. Abd; Isa, N. Mohd

2018-01-01

The linearity of Al2O3 OSL dosimeters (OSLD) were evaluated for dosimetry works in clinical photons and electrons. The measurements were made at a reference depth of Zref according to IAEA TRS 398:2000 codes of practice at 6 and 10 MV photons and 6 and 9 MeV electrons. The measured dose was compared to the thermoluminescence dosimeters (TLD) and ionization chamber commonly used for dosimetry works for higher energy photons and electrons. The results showed that the measured dose in OSL dosimeters were in good agreement with the reported by the ionization chamber in both high energy photons and electrons. A reproducibility test also reported excellent consistency of readings with the OSL at similar energy levels. The overall results confirmed the suitability of OSL dosimeters for dosimetry works involving high energy photons and electrons in radiotherapy.

Radiation Risk From Medical Imaging

PubMed Central

Lin, Eugene C.

2010-01-01

This review provides a practical overview of the excess cancer risks related to radiation from medical imaging. Primary care physicians should have a basic understanding of these risks. Because of recent attention to this issue, patients are more likely to express concerns over radiation risk. In addition, physicians can play a role in reducing radiation risk to their patients by considering these risks when making imaging referrals. This review provides a brief overview of the evidence pertaining to low-level radiation and excess cancer risks and addresses the radiation doses and risks from common medical imaging studies. Specific subsets of patients may be at greater risk from radiation exposure, and radiation risk should be considered carefully in these patients. Recent technical innovations have contributed to lowering the radiation dose from computed tomography, and the referring physician should be aware of these innovations in making imaging referrals. PMID:21123642

Home blood sodium monitoring, sliding-scale fluid prescription and subcutaneous DDAVP for infantile diabetes insipidus with impaired thirst mechanism.

PubMed

Hameed, Shihab; Mendoza-Cruz, Abel C; Neville, Kristen A; Woodhead, Helen J; Walker, Jan L; Verge, Charles F

2012-06-09

Infants with diabetes insipidus (DI), especially those with impaired thirst mechanism or hypothalamic hyperphagia, are prone to severe sodium fluctuations, often requiring hospitalization. We aimed to avoid dangerous fluctuations in serum sodium and improve parental independence. A 16-month old girl with central DI, absent thirst mechanism and hyperphagia following surgery for hypothalamic astrocytoma had erratic absorption of oral DDAVP during chemotherapy cycles. She required prolonged hospitalizations for hypernatremia and hyponatremic seizure. Intensive monitoring of fluid balance, weight and clinical assessment of hydration were not helpful in predicting serum sodium. Discharge home was deemed unsafe. Oral DDAVP was switched to subcutaneous (twice-daily injections, starting with 0.01mcg/dose, increasing to 0.024mcg/dose). The parents adjusted daily fluid allocation by sliding-scale, according to the blood sodium level (measured by handheld i-STAT analyser, Abbott). We adjusted the DDAVP dose if fluid allocation differed from maintenance requirements for 3 consecutive days. After 2.5 months, sodium was better controlled, with 84% of levels within reference range (135-145 mmol/L) vs. only 51% on the old regimen (p = 0.0001). The sodium ranged from 132-154 mmol/L, compared to 120-156 on the old regimen. She was discharged home. This practical regimen improved sodium control, parental independence, and allowed discharge home.

Home blood sodium monitoring, sliding-scale fluid prescription and subcutaneous DDAVP for infantile diabetes insipidus with impaired thirst mechanism

PubMed Central

2012-01-01

Background/Aims Infants with diabetes insipidus (DI), especially those with impaired thirst mechanism or hypothalamic hyperphagia, are prone to severe sodium fluctuations, often requiring hospitalization. We aimed to avoid dangerous fluctuations in serum sodium and improve parental independence. Methods A 16-month old girl with central DI, absent thirst mechanism and hyperphagia following surgery for hypothalamic astrocytoma had erratic absorption of oral DDAVP during chemotherapy cycles. She required prolonged hospitalizations for hypernatremia and hyponatremic seizure. Intensive monitoring of fluid balance, weight and clinical assessment of hydration were not helpful in predicting serum sodium. Discharge home was deemed unsafe. Oral DDAVP was switched to subcutaneous (twice-daily injections, starting with 0.01mcg/dose, increasing to 0.024mcg/dose). The parents adjusted daily fluid allocation by sliding-scale, according to the blood sodium level (measured by handheld i-STAT analyser, Abbott). We adjusted the DDAVP dose if fluid allocation differed from maintenance requirements for 3 consecutive days. Results After 2.5 months, sodium was better controlled, with 84% of levels within reference range (135-145 mmol/L) vs. only 51% on the old regimen (p = 0.0001). The sodium ranged from 132-154 mmol/L, compared to 120–156 on the old regimen. She was discharged home. Conclusion This practical regimen improved sodium control, parental independence, and allowed discharge home. PMID:22682315

Practical Synthesis, Antidepressant, and Anticonvulsant Activity of 3-Phenyliminoindolin-2-one Derivatives.

PubMed

Ma, Jian-Yin; Quan, Ying-Chun; Jin, Hong-Guo; Zhen, Xing-Hua; Zhang, Xue-Wu; Guan, Li-Ping

2016-03-01

Herein, a series of 3-phenyliminoindolin-2-one derivatives were designed, synthesized, and screened for their antidepressant and anticonvulsant activities. The IR spectra of the compounds afforded NH stretching (3340-3346 cm(-1)) bands and C=O stretching (1731-1746 cm(-1)). In the (1)H-NMR spectra of the compounds, N-H protons of indoline ring were observed at 10.65-10.89 ppm generally as broad bands, and (13)C-NMR spectra of the compounds C=O were seen at 161.72-169.27 ppm. Interestingly, compounds 3o, 3p and 3r significantly shortened immobility time in the The forced swimming test (FST) and The tail suspension test (TST) at 50 mg/kg dose levels. In addition, compound 3r exhibited higher levels of efficacy than the reference standard fluoxetine but had no effect on locomotor activity in the open-field test. Compound 3r significantly increased serotonin and norepinephrine and the metabolite 5-hydroxyindoleacetic acid in mouse brain, suggesting that the effects of compound 3r may be mediated through these neurotransmitters. In the seizure screen, 15 compounds showed some degree against PTZ-induced seizure at a dose of 100 mg/kg, and the tested compounds did not show any neurotoxicity at a dose of 300 mg/kg in the rotarod test. © 2015 John Wiley & Sons A/S.

The Effects of Blood Glucose Levels on Cognitive Performance: A Review of the Literature

NASA Technical Reports Server (NTRS)

Feldman, Jolene; Barshi, Immanuel

2007-01-01

The purpose of this review paper is to discuss the research literature on the effects of blood glucose levels on executive and non-executive functions in humans. The review begins with a brief description of blood glucose, how it has been studied, previous syntheses of prior studies, and basic results regarding the role of blood glucose on cognitive functioning. The following sections describe work that investigated the effect of blood glucose on both non-executive and executive functions (e.g., sensory processing, psychomotor functioning, attention, vigilance, memory, language and communication, judgement and decision-making, and complex task performance). Within each section, summaries of the findings and challenges to the literature are included. Measurement conversions of blood glucose levels, blood glucose values, and associated symptoms are depicted. References to the types of tests used to investigate blood glucose and cognitive performance are provided. For more detailed descriptions of references within (and in addition to) this paper, an annotated bibliography is also provided. Several moderator variables including individual differences and contextual variables related to the effects of blood glucose levels on performance (e.g., age, gender, time of day, familiarity with the task and symptom awareness, expectancy effects, dose dependent effects, time dependent effects, task specific effects, rising and falling blood glucose levels, and speed and/or accuracy trade-offs) are addressed later in the paper. Some suggestions for future experimental methodologies are also made.

Influence of terrestrial radionuclides on environmental gamma exposure in a uranium deposit in Paraíba, Brazil.

PubMed

Araújo Dos Santos Júnior, José; Dos Santos Amaral, Romilton; Simões Cezar Menezes, Rômulo; Reinaldo Estevez Álvarez, Juan; Marques do Nascimento Santos, Josineide; Herrero Fernández, Zahily; Dias Bezerra, Jairo; Antônio da Silva, Alberto; Francys Rodrigues Damascena, Kennedy; de Almeida Maciel Neto, José

2017-07-01

One of the main natural uranium deposits in Brazil is located in the municipality of Espinharas, in the State of Paraíba. This area may present high levels of natural radioactivity due to the presence of these radionuclides. Since this is a populated area, there is need for a radioecological dosimetry assessment to investigate the possible risks to the population. Based on this problem, the objective of this study was to estimate the environmental effective dose outdoors in inhabited areas influenced by the uranium deposit, using the specific activities of equivalent uranium, equivalent thorium and 40 K and conversion factors. The environmental assessment was carried using gamma spectroscopy in sixty-two points within the municipality, with a high-resolution gamma spectrometer with HPGe semiconductor detector and Be window. The results obtained ranged from 0.01 to 19.11 mSv y -1 , with an average of 2.64 mSv y -1 . These levels are, on average, 23 times higher than UNSCEAR reference levels and up to 273 times the reference value of the earth's crust for primordial radionuclides. Therefore, given the high radioactivity levels found, we conclude that there is need for further investigation to evaluate the levels of radioactivity in indoor environments, which will reflect more closely the risks of the local population. Copyright © 2017 Elsevier Inc. All rights reserved.

Bioavailability of paracetamol, phenylephrine hydrochloride and guaifenesin in a fixed-combination syrup versus an oral reference product.

PubMed

Janin, Annick; Monnet, Joelle

2014-04-01

The primary objective of this study was to compare the bioavailability of paracetamol, phenylephrine hydrochloride and guaifenesin in a new oral syrup with an established oral reference product. The secondary objective was to compare the safety of the new syrup and the reference product. This was a single-centre, open-label, randomized, reference-replicated, crossover study. Healthy adult volunteers received one dose of syrup and two separate doses of a reference oral liquid formulation in a randomized sequence over three study periods, with a washout interval of ≥ 7 days between study periods. Blood samples were taken regularly postdose and analysed for paracetamol, phenylephrine hydrochloride and guaifenesin concentrations; adverse events were recorded. This study enrolled 45 subjects. For paracetamol and guaifenesin, the syrup and reference product were considered to be bioequivalent. Bioequivalence was not shown for phenylephrine hydrochloride. All adverse events were mild or moderate, most of which were considered formulation related. The syrup did not reach bioequivalence with the reference product, as bioequivalence could not be shown for phenylephrine hydrochloride. This may be due to differences in the excipients between the two products. Both the syrup and the reference product had a good safety profile and were well tolerated.

The ampakine, Org 26576, bolsters early spatial reference learning and retrieval in the Morris water maze: a subchronic, dose-ranging study in rats.

PubMed

Hamlyn, Eugene; Brand, Linda; Shahid, Mohammed; Harvey, Brian H

2009-10-01

Ampakines have shown beneficial effects on cognition in selected animal models of learning. However, their ability to modify long-term spatial memory tasks has not been studied yet. This would lend credence to their possible value in treating disorders of cognition. We evaluated the actions of subchronic Org 26576 administration on spatial reference memory performance in the 5-day Morris water maze task in male Sprague-Dawley rats, at doses of 1, 3 and 10 mg/kg twice daily through intraperitoneal injection over 12 days. Org 26576 exerted a dose and time-dependent effect on spatial learning, with dosages of 3 and 10 mg/kg significantly enhancing acquisition on day 1. Globally, escape latency decreased significantly as the training days progressed in the saline and Org 26576-treated groups, indicating that significant and equal learning had taken place over the learning period. However, at the end of the learning period, all doses of Org 26576 significantly improved spatial memory storage/retrieval without confounding effects in the cued version of the task. Org 26576 offers early phase spatial memory benefits in rats, but particularly enhances search accuracy during reference memory retrieval. These results support its possible utility in treating disorders characterized by deficits in cognitive performance.

Latin American dose survey results in mammography studies under IAEA programme: radiological protection of patients in medical exposures (TSA3).

PubMed

Mora, Patricia; Blanco, Susana; Khoury, Helen; Leyton, Fernando; Cárdenas, Juan; Defaz, María Yolanda; Garay, Fernando; Telón, Flaviano; Aguilar, Juan Garcia; Roas, Norma; Gamarra, Mirtha; Blanco, Daniel; Quintero, Ana Rosa; Nader, Alejandro

2015-03-01

Latin American countries (Argentina, Brazil, Chile, Costa Rica, Cuba, Ecuador, El Salvador, Guatemala, Mexico, Nicaragua, Paraguay, Uruguay and Venezuela) working under the International Atomic Energy Agency (IAEA) Technical Cooperation Programme: TSA3 Radiological Protection of Patients in Medical Exposures have joined efforts in the optimisation of radiation protection in mammography practice. Through surveys of patient doses, the region has a unique database of diagnostic reference levels for analogue and digital equipment that will direct future optimisation activities towards the early detection of breast cancer among asymptomatic women. During RLA9/057 (2007-09) 24 institutions participated with analogue equipment in a dose survey. Regional training on methodology and measurement equipment was addressed in May 2007. The mean glandular dose (DG) was estimated using the incident kerma in air and relevant conversion coefficients for both projections craneo caudal and mediolateral oblique (CC and MLO). For Phase 2, RLA9/067 (2010-11), it was decided to include also digital systems in order to see their impact in future dose optimisation activities. Any new country that joined the project received training in the activities through IAEA expert missions. Twenty-nine new institutions participated (9 analogue and 20 digital equipment). A total of 2262 patient doses were collected during this study and from them D(G) (mGy) for both projections were estimated for each institution and country. Regional results (75 percentile in mGy) show for CC and MLO views, respectively: RLA9/057 (analogue) 2.63 and 3.17; RLA/067: 2.57 and 3.15 (analogue) and 2.69 and 2.90 (digital). Regarding only digital equipment for CC and MLO, respectively, computed radiography systems showed 2.59 and 2.78 and direct digital radiography (DDR) systems 2.78 and 3.04. Based on the IAEA Basic Safety Standard (BSS) reference dose (3 mGy), it can be observed that there is enough room to start optimisation processes in Latin America (LA); several countries or even particular institutions have values much higher than the 3 mGy. The main issues to address are lack of well-established quality assurance programmes for mammography, not enough medical physicists with training in mammography, an increase in patient doses with the introduction of digital equipment and to create awareness on radiation risk and optimisation strategies. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Diagnostic value of different adherence measures using electronic monitoring and virologic failure as reference standards.

PubMed

Deschamps, Ann E; De Geest, Sabina; Vandamme, Anne-Mieke; Bobbaers, Herman; Peetermans, Willy E; Van Wijngaerden, Eric

2008-09-01

Nonadherence to antiretroviral therapy is a substantial problem in HIV and jeopardizes the success of treatment. Accurate measurement of nonadherence is therefore imperative for good clinical management but no gold standard has been agreed on yet. In a single-center prospective study nonadherence was assessed by electronic monitoring: percentage of doses missed and drug holidays and by three self reports: (1) a visual analogue scale (VAS): percentage of overall doses taken; (2) the Swiss HIV Cohort Study Adherence Questionnaire (SHCS-AQ): percentage of overall doses missed and drug holidays and (3) the European HIV Treatment Questionnaire (EHTQ): percentage of doses missed and drug holidays for each antiretroviral drug separately. Virologic failure prospectively assessed during 1 year, and electronic monitoring were used as reference standards. Using virologic failure as reference standard, the best results were for (1) the SHCS-AQ after electronic monitoring (sensitivity, 87.5%; specificity, 78.6%); (2) electronic monitoring (sensitivity, 75%; specificity, 85.6%), and (3) the VAS combined with the SHCS-AQ before electronic monitoring (sensitivity, 87.5%; specificity, 58.6%). The sensitivity of the complex EHTQ was less than 50%. Asking simple questions about doses taken or missed is more sensitive than complex questioning about each drug separately. Combining the VAS with the SHCS-AQ seems a feasible nonadherence measure for daily clinical practice. Self-reports perform better after electronic monitoring: their diagnostic value could be lower when given independently.

External dose-rate conversion factors of radionuclides for air submersion, ground surface contamination and water immersion based on the new ICRP dosimetric setting.

PubMed

Yoo, Song Jae; Jang, Han-Ki; Lee, Jai-Ki; Noh, Siwan; Cho, Gyuseong

2013-01-01

For the assessment of external doses due to contaminated environment, the dose-rate conversion factors (DCFs) prescribed in Federal Guidance Report 12 (FGR 12) and FGR 13 have been widely used. Recently, there were significant changes in dosimetric models and parameters, which include the use of the Reference Male and Female Phantoms and the revised tissue weighting factors, as well as the updated decay data of radionuclides. In this study, the DCFs for effective and equivalent doses were calculated for three exposure settings: skyshine, groundshine and water immersion. Doses to the Reference Phantoms were calculated by Monte Carlo simulations with the MCNPX 2.7.0 radiation transport code for 26 mono-energy photons between 0.01 and 10 MeV. The transport calculations were performed for the source volume within the cut-off distances practically contributing to the dose rates, which were determined by a simplified calculation model. For small tissues for which the reduction of variances are difficult, the equivalent dose ratios to a larger tissue (with lower statistical errors) nearby were employed to make the calculation efficient. Empirical response functions relating photon energies, and the organ equivalent doses or the effective doses were then derived by the use of cubic-spline fitting of the resulting doses for 26 energy points. The DCFs for all radionuclides considered important were evaluated by combining the photon emission data of the radionuclide and the empirical response functions. Finally, contributions of accompanied beta particles to the skin equivalent doses and the effective doses were calculated separately and added to the DCFs. For radionuclides considered in this study, the new DCFs for the three exposure settings were within ±10 % when compared with DCFs in FGR 13.

External dose-rate conversion factors of radionuclides for air submersion, ground surface contamination and water immersion based on the new ICRP dosimetric setting

PubMed Central

Yoo, Song Jae; Jang, Han-Ki; Lee, Jai-Ki; Noh, Siwan; Cho, Gyuseong

2013-01-01

For the assessment of external doses due to contaminated environment, the dose-rate conversion factors (DCFs) prescribed in Federal Guidance Report 12 (FGR 12) and FGR 13 have been widely used. Recently, there were significant changes in dosimetric models and parameters, which include the use of the Reference Male and Female Phantoms and the revised tissue weighting factors, as well as the updated decay data of radionuclides. In this study, the DCFs for effective and equivalent doses were calculated for three exposure settings: skyshine, groundshine and water immersion. Doses to the Reference Phantoms were calculated by Monte Carlo simulations with the MCNPX 2.7.0 radiation transport code for 26 mono-energy photons between 0.01 and 10 MeV. The transport calculations were performed for the source volume within the cut-off distances practically contributing to the dose rates, which were determined by a simplified calculation model. For small tissues for which the reduction of variances are difficult, the equivalent dose ratios to a larger tissue (with lower statistical errors) nearby were employed to make the calculation efficient. Empirical response functions relating photon energies, and the organ equivalent doses or the effective doses were then derived by the use of cubic-spline fitting of the resulting doses for 26 energy points. The DCFs for all radionuclides considered important were evaluated by combining the photon emission data of the radionuclide and the empirical response functions. Finally, contributions of accompanied beta particles to the skin equivalent doses and the effective doses were calculated separately and added to the DCFs. For radionuclides considered in this study, the new DCFs for the three exposure settings were within ±10 % when compared with DCFs in FGR 13. PMID:23542764

Bayesian methods for uncertainty factor application for derivation of reference values.

PubMed

Simon, Ted W; Zhu, Yiliang; Dourson, Michael L; Beck, Nancy B

2016-10-01

In 2014, the National Research Council (NRC) published Review of EPA's Integrated Risk Information System (IRIS) Process that considers methods EPA uses for developing toxicity criteria for non-carcinogens. These criteria are the Reference Dose (RfD) for oral exposure and Reference Concentration (RfC) for inhalation exposure. The NRC Review suggested using Bayesian methods for application of uncertainty factors (UFs) to adjust the point of departure dose or concentration to a level considered to be without adverse effects for the human population. The NRC foresaw Bayesian methods would be potentially useful for combining toxicity data from disparate sources-high throughput assays, animal testing, and observational epidemiology. UFs represent five distinct areas for which both adjustment and consideration of uncertainty may be needed. NRC suggested UFs could be represented as Bayesian prior distributions, illustrated the use of a log-normal distribution to represent the composite UF, and combined this distribution with a log-normal distribution representing uncertainty in the point of departure (POD) to reflect the overall uncertainty. Here, we explore these suggestions and present a refinement of the methodology suggested by NRC that considers each individual UF as a distribution. From an examination of 24 evaluations from EPA's IRIS program, when individual UFs were represented using this approach, the geometric mean fold change in the value of the RfD or RfC increased from 3 to over 30, depending on the number of individual UFs used and the sophistication of the assessment. We present example calculations and recommendations for implementing the refined NRC methodology. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

Overview of ICRP Committee 5: protection of the environment.

PubMed

Larsson, C-M

2016-06-01

Protection of the environment is integral to the system of radiological protection, as outlined in the 2007 Recommendations of the International Commission on Radiological Protection (ICRP, Publication 103). The Commission's activities in this area are mainly pursued by Committee 5 and its associated Task Groups. Publication 91 broadly outlines the approach to radiological protection of the environment, and its alignment with approaches to environmental protection from hazardous substances in general. Publications 108 and 114 provide the cornerstones of the environmental protection system and relevant databases. Publication 124 considers its application in planned, existing, and emergency exposure situations. The system centres on 12 Reference Animals and Plants (RAPs) with broad relevance for environmental protection based on their ubiquity and significance as well as other criteria, as described in Publication 108 The databases comprise general biology of the RAPs, transfer parameters, dose conversion coefficients, and effects data. Derived Consideration Reference Levels (DCRLs) were established for each RAP; a DCRL represents a band of dose rates that might result in some deleterious effects in individuals of that type of RAP. Newly established Task Group 99 will compile the RAP-specific reference information into monographs, with the view of updating information and improving the applicability of the system in different exposure situations. For certain scenarios, more precise and ecosystem-specific protection benchmarks may be justified, which would have to be informed by consideration of representative organisms (i.e. representative of a particular ecosystem and relevant to the specific scenario; Publication 124). Committee 5 will explore this further, making use of a limited number of case studies. © The International Society for Prosthetics and Orthotics.

Survey of undeclared soy allergen levels in the most frequently recalled food categories with or without precautionary labelling.

PubMed

Khuda, Sefat E; Sharma, Girdhari M; Gaines, Dennis; Do, Andrew B; Pereira, Marion; Chang, Michael; Ferguson, Martine; Williams, Kristina M

2016-08-01

A comprehensive study was designed to determine the frequency and levels of soy allergen in packaged bakery and snack food products. A representative sample of products with no soy allergen disclosed on the label was analysed using two widely used enzyme-linked immunosorbent assay (ELISA) methods. Samples were chosen that either had no soy identified on the product label or which had a soy precautionary statement. Among 558 bakery and snack products, soy protein was detected in 17% of the products using the Neogen (NE) kit and 11% of the products using the Elisa Systems (ES) kit. The disagreement rates between kits were 8.8% for bakery products and 3.3% for snack products. Overall soy protein was detected at higher frequency in bakery products than in snack foods. Among 284 bakery samples, soy protein was detected in 25% of the samples with no precautionary statement and 19% of the samples which had a precautionary statement. Among 274 snack samples, soy protein was detected in 11% of the samples with no precautionary statement and 9% of the samples which had a precautionary statement. The sample repeatability was at an acceptable level (< 9%) for each method and food commodity. The reproducibility between kits was 23% for bakery foods and 36% for snack foods. None of the bakery (21) and snack (6) products without precautionary labelling (measured level > 5 ppm) had a higher level of soy protein per serving compared with the eliciting dose10 (ED10) of 10.6 mg for soy allergic patients. But the level of soy protein per serving may be clinically relevant to a subpopulation of soy allergic patients if a more stringent eliciting dose is applied. These findings emphasise that suitable detection methodologies and references doses are crucial for labelling accuracy and the safety of soy allergic consumers.

Organ doses, effective doses, and risk indices in adult CT: Comparison of four types of reference phantoms across different examination protocols

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

Zhang Yakun; Li Xiang; Paul Segars, W.

Purpose: Radiation exposure from computed tomography (CT) to the public has increased the concern among radiation protection professionals. Being able to accurately assess the radiation dose patients receive during CT procedures is a crucial step in the management of CT dose. Currently, various computational anthropomorphic phantoms are used to assess radiation dose by different research groups. It is desirable to better understand how the dose results are affected by different choices of phantoms. In this study, the authors assessed the uncertainties in CT dose and risk estimation associated with different types of computational phantoms for a selected group of representativemore » CT protocols. Methods: Routinely used CT examinations were categorized into ten body and three neurological examination categories. Organ doses, effective doses, risk indices, and conversion coefficients to effective dose and risk index (k and q factors, respectively) were estimated for these examinations for a clinical CT system (LightSpeed VCT, GE Healthcare). Four methods were used, each employing a different type of reference phantoms. The first and second methods employed a Monte Carlo program previously developed and validated in our laboratory. In the first method, the reference male and female extended cardiac-torso (XCAT) phantoms were used, which were initially created from the Visible Human data and later adjusted to match organ masses defined in ICRP publication 89. In the second method, the reference male and female phantoms described in ICRP publication 110 were used, which were initially developed from tomographic data of two patients and later modified to match ICRP 89 organ masses. The third method employed a commercial dosimetry spreadsheet (ImPACT group, London, England) with its own hermaphrodite stylized phantom. In the fourth method, another widely used dosimetry spreadsheet (CT-Expo, Medizinische Hochschule, Hannover, Germany) was employed together with its associated male and female stylized phantoms. Results: For fully irradiated organs, average coefficients of variation (COV) ranged from 0.07 to 0.22 across the four male phantoms and from 0.06 to 0.18 across the four female phantoms; for partially irradiated organs, average COV ranged from 0.13 to 0.30 across the four male phantoms and from 0.15 to 0.30 across the four female phantoms. Doses to the testes, breasts, and esophagus showed large variations between phantoms. COV for gender-averaged effective dose and k factor ranged from 0.03 to 0.23 and from 0.06 to 0.30, respectively. COV for male risk index and q factor ranged from 0.06 to 0.30 and from 0.05 to 0.36, respectively; COV for female risk index and q factor ranged from 0.06 to 0.49 and from 0.07 to 0.54, respectively. Conclusions: Despite closely matched organ mass, total body weight, and height, large differences in organ dose exist due to variation in organ location, spatial distribution, and dose approximation method. Dose differences for fully irradiated radiosensitive organs were much smaller than those for partially irradiated organs. Weighted dosimetry quantities including effective dose, male risk indices, k factors, and male q factors agreed well across phantoms. The female risk indices and q factors varied considerably across phantoms.« less

Organ doses, effective doses, and risk indices in adult CT: Comparison of four types of reference phantoms across different examination protocols

PubMed Central

Zhang, Yakun; Li, Xiang; Paul Segars, W.; Samei, Ehsan

2012-01-01

Purpose: Radiation exposure from computed tomography (CT) to the public has increased the concern among radiation protection professionals. Being able to accurately assess the radiation dose patients receive during CT procedures is a crucial step in the management of CT dose. Currently, various computational anthropomorphic phantoms are used to assess radiation dose by different research groups. It is desirable to better understand how the dose results are affected by different choices of phantoms. In this study, the authors assessed the uncertainties in CT dose and risk estimation associated with different types of computational phantoms for a selected group of representative CT protocols. Methods: Routinely used CT examinations were categorized into ten body and three neurological examination categories. Organ doses, effective doses, risk indices, and conversion coefficients to effective dose and risk index (k and q factors, respectively) were estimated for these examinations for a clinical CT system (LightSpeed VCT, GE Healthcare). Four methods were used, each employing a different type of reference phantoms. The first and second methods employed a Monte Carlo program previously developed and validated in our laboratory. In the first method, the reference male and female extended cardiac-torso (XCAT) phantoms were used, which were initially created from the Visible Human data and later adjusted to match organ masses defined in ICRP publication 89. In the second method, the reference male and female phantoms described in ICRP publication 110 were used, which were initially developed from tomographic data of two patients and later modified to match ICRP 89 organ masses. The third method employed a commercial dosimetry spreadsheet (ImPACT group, London, England) with its own hermaphrodite stylized phantom. In the fourth method, another widely used dosimetry spreadsheet (CT-Expo, Medizinische Hochschule, Hannover, Germany) was employed together with its associated male and female stylized phantoms. Results: For fully irradiated organs, average coefficients of variation (COV) ranged from 0.07 to 0.22 across the four male phantoms and from 0.06 to 0.18 across the four female phantoms; for partially irradiated organs, average COV ranged from 0.13 to 0.30 across the four male phantoms and from 0.15 to 0.30 across the four female phantoms. Doses to the testes, breasts, and esophagus showed large variations between phantoms. COV for gender-averaged effective dose and k factor ranged from 0.03 to 0.23 and from 0.06 to 0.30, respectively. COV for male risk index and q factor ranged from 0.06 to 0.30 and from 0.05 to 0.36, respectively; COV for female risk index and q factor ranged from 0.06 to 0.49 and from 0.07 to 0.54, respectively. Conclusions: Despite closely matched organ mass, total body weight, and height, large differences in organ dose exist due to variation in organ location, spatial distribution, and dose approximation method. Dose differences for fully irradiated radiosensitive organs were much smaller than those for partially irradiated organs. Weighted dosimetry quantities including effective dose, male risk indices, k factors, and male q factors agreed well across phantoms. The female risk indices and q factors varied considerably across phantoms. PMID:22755721

Sub-chronic safety evaluation of the ethanol extract of Aralia elata leaves in Beagle dogs.

PubMed

Li, Fengjin; He, Xiaoli; Niu, Wenying; Feng, Yuenan; Bian, Jingqi; Kuang, Haixue; Xiao, Hongbin

2016-08-01

Aralia elata Seem. (A. elata) is a traditional Chinese medicine to treat some diseases. This investigation aims to evaluate the pharmaceutical safety of the ethanol extract of A. elata leaves, namely ethanol leaves extract (ELE), in Beagle dogs. In sub-chronic oral toxicity study, dogs were treated with the ELE at doses of 50, 100 and 200 mg/kg for 12 weeks and followed by 4 weeks recovery period. During experimental period, clinical signs, mortality, body temperature, food consumption and body weight were recorded. Analysis of electrocardiogram, urinalysis, ophthalmoscopy, hematology, serum biochemistry, organ weights and histopathology were performed. The results showed that both food consumption and body weight significantly decreased in high-dose group. Treatment-related side effects and mortality were observed in high-dose female dogs. Some parameters showed significant alterations in electrocardiogram, urinalysis, serum biochemistry and relative organ weights. These alterations were not related to dose or consistent across gender, which were ascribed to incidental and biological variability. The findings in this study indicated that the no-observed adverse effect level (NOAEL) of the ELE was 100 mg/kg in dogs and provided a vital reference for selecting a safe application dosage for human consumption. Copyright © 2016 Elsevier Inc. All rights reserved.

Caffeine tolerance: behavioral, electrophysiological and neurochemical evidence

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

Chou, D.T.; Khan, S.; Forde, J.

The development of tolerance to the stimulatory action of caffeine upon mesencephalic reticular neurons and upon spontaneous locomotor activity was evaluated in rats after two weeks of chronic exposure to low doses of caffeine (5-10 mg/kg/day via their drinking water). These doses are achievable through dietary intake of caffeine-containing beverages in man. Concomitant measurement of (/sup 3/H)-CHA binding in the mesencephalic reticular formation was also carried out in order to explore the neurochemical basis of the development of tolerance. Caffeine, 2.5 mg/kg i.v., markedly increased the firing rate of reticular neurons in caffeine naive rats but failed to modify themore » neuronal activity in a group exposed chronically to low doses of caffeine. In addition, in spontaneous locomotor activity studies, the data show a distinct shift to the right of the caffeine dose-response curve in caffeine pretreated rats. These results clearly indicate that tolerance develops to the stimulatory action of caffeine upon the reticular formation at the single neuronal activity level as well as upon spontaneous locomotor activity. Furthermore, in chronically caffeine exposed rats, an increase in the number of binding sites for (/sup 3/H)-CHA was observed in reticular formation membranes without any change in receptor affinity. 28 references, 4 figures.« less

Patient-Centered Imaging: Shared Decision Making for Cardiac Imaging Procedures with Exposure to Ionizing Radiation

PubMed Central

Einstein, Andrew J.; Berman, Daniel S.; Min, James K.; Hendel, Robert C.; Gerber, Thomas C.; Carr, J. Jeffrey; Cerqueira, Manuel D.; Cullom, S. James; DeKemp, Robert; Dickert, Neal; Dorbala, Sharmila; Garcia, Ernest V.; Gibbons, Raymond J.; Halliburton, Sandra S.; Hausleiter, Jörg; Heller, Gary V.; Jerome, Scott; Lesser, John R.; Fazel, Reza; Raff, Gilbert L.; Tilkemeier, Peter; Williams, Kim A.; Shaw, Leslee J.

2014-01-01

Objective To identify key components of a radiation accountability framework fostering patient-centered imaging and shared decision-making in cardiac imaging. Background An NIH-NHLBI/NCI-sponsored symposium was held in November 2012 to address these issues. Methods Symposium participants, working in three tracks, identified key components of a framework to target critical radiation safety issues for the patient, the laboratory, and the larger population of patients with known or suspected cardiovascular disease. Results Use of ionizing radiation during an imaging procedure should be disclosed to all patients by the ordering provider at the time of ordering, and reinforced by the performing provider team. An imaging protocol with effective dose ≤3mSv is considered very low risk, not warranting extensive discussion or written consent. However, a protocol effective dose <20mSv was proposed as a level requiring particular attention in terms of shared decision-making and either formal discussion or written informed consent. Laboratory reporting of radiation dosimetry is a critical component of creating a quality laboratory fostering a patient-centered environment with transparent procedural methodology. Efforts should be directed to avoiding testing involving radiation, in patients with inappropriate indications. Standardized reporting and diagnostic reference levels for computed tomography and nuclear cardiology are important for the goal of public reporting of laboratory radiation dose levels in conjunction with diagnostic performance. Conclusions The development of cardiac imaging technologies revolutionized cardiology practice by allowing routine, noninvasive assessment of myocardial perfusion and anatomy. It is now incumbent upon the imaging community to create an accountability framework to safely drive appropriate imaging utilization. PMID:24530677

Effect of x-ray tube parameters and iodine concentration on image quality and radiation dose in cerebral pediatric and adult CT angiography: a phantom study.

PubMed

Papadakis, Antonios E; Perisinakis, Kostas; Raissaki, Maria; Damilakis, John

2013-04-01

The aim of the present phantom study was to investigate the effect of x-ray tube parameters and iodine concentration on image quality and radiation dose in cerebral computed tomographic (CT) angiographic examinations of pediatric and adult individuals. Four physical anthropomorphic phantoms that represent the average individual as neonate, 1-year-old, 5-year-old, and 10-year-old children and the RANDO phantom that simulates the average adult individual were used. Cylindrical vessels were bored along the brain-equivalent plugs of each physical phantom. To simulate the brain vasculature, vessels of 0.6, 1, 2, and 3 mm in diameter were created. These vessels were filled with contrast medium (CM) solutions at different iodine concentrations, that is, 5.6, 4.2, 2.7, and 1.4 mg I/mL. The phantom heads were scanned at 120, 100, and 80 kV. The applied quality reference tube current-time product values ranged from a minimum of 45 to a maximum of 680. The CT acquisitions were performed on a 16-slice CT scanner using the automatic exposure control system. Image quality was evaluated on the basis of image noise and contrast-to-noise ratio (CNR) between the contrast-enhanced iodinated vessels and the unenhanced regions of interest. Dose reduction was calculated as the percentage difference of the CT dose index value at the quality reference tube current-time product and the CT dose index at the mean modulated tube current-time product. Image noise that was measured using the preset tube current-time product settings varied significantly among the different phantoms (P < 0.0001). Hounsfield unit number of iodinated vessels was linearly related to CM concentration (r² = 0.907) and vessel diameter (r² = 0.918). The Hounsfield unit number of iodinated vessels followed a decreasing trend from the neonate phantom to the adult phantom at all kilovoltage settings. For the same image noise level, a CNR improvement of up to 69% and a dose reduction of up to 61% may be achieved when CT acquisition is performed at 80 kV compared with 120 kV. For the same CNR, a reduction by 25% of the administered CM concentration may be achieved when CT acquisition is performed at 80 kV compared with 120 kV. In cerebral CT angiographic studies, appropriate adjustment of the preset tube current-time product settings is required to achieve the same image noise level among participants of different age. Cerebral CT angiography at 80 kV significantly improves CNR and significantly reduces radiation dose. Moreover, at 80 kV, a considerable reduction of the administered amount of the CM may be reached, thus reducing potential risks for contrast-induced nephropathy.

Evaluating exposure and potential effects on honeybee brood (Apis mellifera) development using glyphosate as an example.

PubMed

Thompson, Helen M; Levine, Steven L; Doering, Janine; Norman, Steve; Manson, Philip; Sutton, Peter; von Mérey, Georg

2014-07-01

This study aimed to develop an approach to evaluate potential effects of plant protection products on honeybee brood with colonies at realistic worst-case exposure rates. The approach comprised 2 stages. In the first stage, honeybee colonies were exposed to a commercial formulation of glyphosate applied to flowering Phacelia tanacetifolia with glyphosate residues quantified in relevant matrices (pollen and nectar) collected by foraging bees on days 1, 2, 3, 4, and 7 postapplication and glyphosate levels in larvae were measured on days 4 and 7. Glyphosate levels in pollen were approximately 10 times higher than in nectar and glyphosate demonstrated rapid decline in both matrices. Residue data along with foraging rates and food requirements of the colony were then used to set dose rates in the effects study. In the second stage, the toxicity of technical glyphosate to developing honeybee larvae and pupae, and residues in larvae, were then determined by feeding treated sucrose directly to honeybee colonies at dose rates that reflect worst-case exposure scenarios. There were no significant effects from glyphosate observed in brood survival, development, and mean pupal weight. Additionally, there were no biologically significant levels of adult mortality observed in any glyphosate treatment group. Significant effects were observed only in the fenoxycarb toxic reference group and included increased brood mortality and a decline in the numbers of bees and brood. Mean glyphosate residues in larvae were comparable at 4 days after spray application in the exposure study and also following dosing at a level calculated from the mean measured levels in pollen and nectar, showing the applicability and robustness of the approach for dose setting with honeybee brood studies. This study has developed a versatile and predictive approach for use in higher tier honeybee toxicity studies. It can be used to realistically quantify exposure of colonies to pesticides to allow the appropriate dose rates to be determined, based on realistic worst-case residues in pollen and nectar and estimated intake by the colony, as shown by the residue analysis. Previous studies have used the standard methodology developed primarily to identify pesticides with insect-growth disrupting properties of pesticide formulations, which are less reliant on identifying realistic exposure scenarios. However, this adaptation of the method can be used to determine dose-response effects of colony level exposure to pesticides with a wide range of properties. This approach would limit the number of replicated tunnel or field-scale studies that need to be undertaken to assess effects on honeybee brood and may be of particular benefit where residues in pollen and nectar are crop- and/or formulation-specific, such as systemic seed treatments and granular applications. © 2014 The Authors. Integrated Environmental Assessment and Management Published by SETAC.