Dose rate evaluation of workers on the operation floor in Fukushima-Daiichi Unit 3

NASA Astrophysics Data System (ADS)

Matsushita, Kaoru; Kurosawa, Masahiko; Shirai, Keisuke; Matsuoka, Ippei; Mukaida, Naoki

2017-09-01

At Fukushima Daiichi Nuclear Power Plant Unit 3, installation of a fuel handling machine is planned to support the removal of spent fuel. The dose rates at the workplace were calculated based on the source distribution measured using a collimator in order to confirm that the dose rates on the operation floor were within a manageable range. It was confirmed that the accuracy of the source distribution was C/M = 1.0-2.4. These dose rates were then used to plan the work on the operation floor.

Biological X-ray irradiator characterization for use with small animals and cells.

PubMed

Bruno, A Colello; Mazaro, S J; Amaral, L L; Rego, E M; Oliveira, H F; Pavoni, J F

2017-03-02

This study presents the characterization of an X-ray irradiator through dosimetric tests, which confirms the actual dose rate that small animals and cells will be exposed to during radiobiological experiments. We evaluated the linearity, consistency, repeatability, and dose distribution in the positions in which the animals or cells are placed during irradiation. In addition, we evaluated the performance of the X-ray tube (voltage and tube operating current), the radiometric survey (leakage radiation) and safety devices. The irradiator default setting was established as 160 kV and 25 mA. Tests showed that the dose rate was linear overtime (R2=1) and remained stable for long (constant) and short (repeatability) intervals between readings. The mean dose rate inside the animal cages was 1.27±0.06 Gy/min with a uniform beam of 95.40% (above the minimum threshold guaranteed by the manufacturer). The mean dose rate inside the cell plates was 0.92±0.19 Gy/min. The dose rate dependence with tube voltage and current presented a quadratic and linear relationship, respectively. There was no observed mechanical failure during evaluation of the irradiator safety devices and the radiometric survey obtained a maximum ambient equivalent dose rate of 0.26 mSv/h, which exempts it from the radiological protection requirements of the International Atomic Energy Agency. The irradiator characterization enables us to perform radiobiological experiments, and assists or even replaces traditional therapy equipment (e.g., linear accelerators) for cells and small animal irradiation, especially in early research stages.

SU-F-J-45: Sparing Normal Tissue with Ultra-High Dose Rate in Radiation Therapy

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

Feng, Y

Purpose: To spare normal tissue by reducing the location uncertainty of a moving target, we proposed an ultra-high dose rate system and evaluated. Methods: High energy electrons generated with a linear accelerator were injected into a storage ring to be accumulated. The number of the electrons in the ring was determined based on the prescribed radiation dose. The dose was delivered within a millisecond, when an online imaging system found that the target was in the position that was consistent with that in a treatment plan. In such a short time period, the displacement of the target was negligible. Themore » margin added to the clinical target volume (CTV) could be reduced that was evaluated by comparing of volumes between CTV and ITV in 14 cases of lung stereotactic body radiation therapy (SBRT) treatments. A design of the ultra-high dose rate system was evaluated based clinical needs and the recent developments of low energy (a few MeV) electron storage ring. Results: This design of ultra-high dose rate system was feasible based on the techniques currently available. The reduction of a target volume was significant by reducing the margin that accounted the motion of the target. ∼50% volume reduction of the internal target volume (ITV) could be achieved in lung SBRT treatments. Conclusion: With this innovation of ultra-high dose rate system, the margin of target is able to be significantly reduced. It will reduce treatment time of gating and allow precisely specified gating window to improve the accuracy of dose delivering.« less

Correlation of radiation dose and heart rate in dual-source computed tomography coronary angiography.

PubMed

Laspas, Fotios; Tsantioti, Dimitra; Roussakis, Arkadios; Kritikos, Nikolaos; Efthimiadou, Roxani; Kehagias, Dimitrios; Andreou, John

2011-04-01

Computed tomography coronary angiography (CTCA) has been widely used since the introduction of 64-slice scanners and dual-source CT technology, but the relatively high radiation dose remains a major concern. To evaluate the relationship between radiation exposure and heart rate (HR), in dual-source CTCA. Data from 218 CTCA examinations, performed with a dual-source 64-slices scanner, were statistically evaluated. Effective radiation dose, expressed in mSv, was calculated as the product of the dose-length product (DLP) times a conversion coefficient for the chest (mSv = DLPx0.017). Heart rate range and mean heart rate, expressed in beats per minute (bpm) of each individual during CTCA, were also provided by the system. Statistical analysis of effective dose and heart rate data was performed by using Pearson correlation coefficient and two-sample t-test. Mean HR and effective dose were found to have a borderline positive relationship. Individuals with a mean HR >65 bpm observed to receive a statistically significant higher effective dose as compared to those with a mean HR ≤65 bpm. Moreover, a strong correlation between effective dose and variability of HR of more than 20 bpm was observed. Dual-source CT scanners are considered to have the capability to provide diagnostic examinations even with high HR and arrhythmias. However, it is desirable to keep the mean heart rate below 65 bpm and heart rate fluctuation less than 20 bpm in order to reduce the radiation exposure.

SU-E-T-145: Beam Characteristics of Flattening Filter Free Beams Including Low Dose Rate Setting

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

Uehara, K; Ogata, T; Nakayama, M

2015-06-15

Purpose: In commissioning of volumetric modulated arc therapy (VMAT), it is necessary to evaluate the beam characteristics of various dose rate settings with potential to use. The aim of this study is to evaluate the beam characteristics of flattened and flattening filter free (FFF) including low dose rate setting. Methods: We used a Varian TrueBeam with Millennium 120 MLC. Both 6 and 10 MV beams with or without flattening filter were used for this study. To evaluate low-dose rate FFF beams, specially-designed leaf sequence files control out-of-field MLC leaf pair at constant dose rate ranging from 80 to 400 MU/min.more » For dose rate from 80 MU/min to the maximum usable value of all energies, beam output were measured using ionization chamber (CC04, IBA). The ionization chamber was inserted into water equivalent phantom (RT3000-New, R-tech), and the phantom was set with SAD of 100cm. The beam profiles were performed using the 2D diode array (Profiler2, Sun Nuclear). The SSD was set to 90cm and a combined 30cmx30cmx9cm phantom which consisted of solid water slabs was put on the device. All measurement were made using 100MU irradiation for 10cmx10cm jaw-defined field size with a gantry angle of 0°. Results: In all energies, the dose rate dependences with beam output and variation coefficient were within 0.2% and 0.07%, respectively. The flatness and symmetry exhibited small variations (flatness ≤0.1 point and symmetry≤0.3 point at absolute difference). Conclusion: We had studied the characteristics of flattened and FFF beam over the 80 MU/min. Our results indicated that the beam output and profiles of FFF of TrueBeam linac were highly stable at low dose rate setting.« less

Impact of a phenytoin loading dose program in the emergency department.

PubMed

Brancaccio, Adam; Giuliano, Christopher; McNorton, Kelly; Delgado, George

2014-11-01

The use of a combined physician-and pharmacist-directed phenytoin loading dose program in an emergency department (ED) was evaluated. This single-center, observational, preimplementation-postimplementation study evaluated adult patients who received a phenytoin loading dose in the ED. The primary outcome compared the proportion of optimal phenytoin loading doses in the preimplementation and postimplementation groups. The postimplementation group was further stratified into pharmacist- and prescriber-dosing groups. Other outcomes evaluated included the numbers of appropriate serum phenytoin concentrations measured, adverse drug reactions (ADRs), and recurrence of seizures within 24 hours of loading dose administration in the preimplementation and postimplementation groups. There was no difference in the proportion of optimal phenytoin loading doses between the preimplementation and postimplementation groups (50% versus 62%, respectively; p=0.19). When stratified by individual groups, the rate of optimal phenytoin loading doses increased by 64% in the postimplementation pharmacist group (50% versus 82%, p=0.007), while the rate in the prescriber-dosing group remained relatively unchanged (50% versus 49%, p=0.91). The number of appropriate serum phenytoin concentrations significantly improved in the postimplementation versus preimplementation group (65% versus 40%, p=0.025). Rates of ADRs and recurrence of seizures did not differ across the study groups. No change in the percentage of optimal phenytoin loading doses in the ED was observed after implementation of a combined pharmacist- and physician- dosing program. When stratified into pharmacist or prescriber dosing, the pharmacist-led dosing program significantly improved the proportion of patients who received optimal phenytoin loading doses. Copyright © 2014 by the American Society of Health-System Pharmacists, Inc. All rights reserved.

Polymer gel dosimeters for pretreatment radiotherapy verification using the three-dimensional gamma evaluation and pass rate maps.

PubMed

Hsieh, Ling-Ling; Shieh, Jiunn-I; Wei, Li-Ju; Wang, Yi-Chun; Cheng, Kai-Yuan; Shih, Cheng-Ting

2017-05-01

Polymer gel dosimeters (PGDs) have been widely studied for use in the pretreatment verification of clinical radiation therapy. However, the readability of PGDs in three-dimensional (3D) dosimetry remain unclear. In this study, the pretreatment verifications of clinical radiation therapy were performed using an N-isopropyl-acrylamide (NIPAM) PGD, and the results were used to evaluate the performance of the NIPAM PGD on 3D dose measurement. A gel phantom was used to measure the dose distribution of a clinical case of intensity-modulated radiation therapy. Magnetic resonance imaging scans were performed for dose readouts. The measured dose volumes were compared with the planned dose volume. The relative volume histograms showed that relative volumes with a negative percent dose difference decreased as time elapsed. Furthermore, the histograms revealed few changes after 24h postirradiation. For the 3%/3mm and 2%/2mm criteria, the pass rates of the 12- and 24-h dose volumes were higher than 95%, respectively. This study thus concludes that the pass rate map can be used to evaluate the dose-temporal readability of PGDs and that the NIPAM PGD can be used for clinical pretreatment verifications. Copyright © 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

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

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.

Uveal Melanoma Treated With Iodine-125 Episcleral Plaque: An Analysis of Dose on Disease Control and Visual Outcomes

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

Perez, Bradford A.; Mettu, Pradeep; Vajzovic, Lejla

2014-05-01

Purpose: To investigate, in the treatment of uveal melanomas, how tumor control, radiation toxicity, and visual outcomes are affected by the radiation dose at the tumor apex. Methods and Materials: A retrospective review was performed to evaluate patients treated for uveal melanoma with {sup 125}I plaques between 1988 and 2010. Radiation dose is reported as dose to tumor apex and dose to 5 mm. Primary endpoints included time to local failure, distant failure, and death. Secondary endpoints included eye preservation, visual acuity, and radiation-related complications. Univariate and multivariate analyses were performed to determine associations between radiation dose and the endpointmore » variables. Results: One hundred ninety patients with sufficient data to evaluate the endpoints were included. The 5-year local control rate was 91%. The 5-year distant metastases rate was 10%. The 5-year overall survival rate was 84%. There were no differences in outcome (local control, distant metastases, overall survival) when dose was stratified by apex dose quartile (<69 Gy, 69-81 Gy, 81-89 Gy, >89 Gy). However, increasing apex dose and dose to 5-mm depth were correlated with greater visual acuity loss (P=.02, P=.0006), worse final visual acuity (P=.02, P<.0001), and radiation complications (P<.0001, P=.0009). In addition, enucleation rates were worse with increasing quartiles of dose to 5 mm (P=.0001). Conclusions: Doses at least as low as 69 Gy prescribed to the tumor apex achieve rates of local control, distant metastasis–free survival, and overall survival that are similar to radiation doses of 85 Gy to the tumor apex, but with improved visual outcomes.« less

The evaluation the magnitude radiation exposure dose rate in digital radiography room design

NASA Astrophysics Data System (ADS)

Dwiyanto, Agung; Setia Budi, Wahyu; Hardiman, Gagoek

2017-12-01

This study discusses the dose rate in digital radiography room, buit according to meet the provisions of KEMENKES No.1014 / Menkes / SK / XI / 2008 and Regulation of BAPETEN No. 8 / 2011. The provisions primary concern of radiation safety, not comfort, by considering the space design. There are five aspects to consider in designing the space: functionality, comfort, security, movement activities and aesthetics. However provisions only met three aspects of the design, which are a function, security and movement activity. Therefore, it is necessary to evaluate digital radiography room in terms of its ability to control external radiation exposure to be safe and comfortable The dose rate is measured by the range of primary and secondary radiation in the observation points by using Surveymeter. All data are obtained by the preliminary survey prior to the study. Furthermore, the review of digital radiography room is done based on architectural design theory. The dose rate for recommended improvement room is recalculated using the same method as the actual room with the help of computer modeling. The result of dose rate calculation at the inner and outer part of digital radiography observation room shows that in-room dose for a week at each measuring point exceeds the allowable dose limit both for staff and public. During a week of observation, the outdoor dose at some measuring points exceeds the dose limit set by the KEMENKES No.1014 / Menkes / SK / XI / 2008 and Regulation BEPETEN No 8/2011. Meanwhile, the result of dose rate calculation in the inner and outer part of the improved digital radiography room can meet the applicable regulations better.

The susceptibility of TaO x-based memristors to high dose rate ionizing radiation and total ionizing dose

DOE PAGES

McLain, Michael Lee; Sheridan, Timothy J.; Hjalmarson, Harold Paul; ...

2014-11-11

This paper investigates the effects of high dose rate ionizing radiation and total ionizing dose (TID) on tantalum oxide (TaO x) memristors. Transient data were obtained during the pulsed exposures for dose rates ranging from approximately 5.0 ×10 7 rad(Si)/s to 4.7 ×10 8 rad(Si)/s and for pulse widths ranging from 50 ns to 50 μs. The cumulative dose in these tests did not appear to impact the observed dose rate response. Static dose rate upset tests were also performed at a dose rate of ~3.0 ×10 8 rad(Si)/s. This is the first dose rate study on any type ofmore » memristive memory technology. In addition to assessing the tolerance of TaO x memristors to high dose rate ionizing radiation, we also evaluated their susceptibility to TID. The data indicate that it is possible for the devices to switch from a high resistance off-state to a low resistance on-state in both dose rate and TID environments. The observed radiation-induced switching is dependent on the irradiation conditions and bias configuration. Furthermore, the dose rate or ionizing dose level at which a device switches resistance states varies from device to device; the enhanced susceptibility observed in some devices is still under investigation. As a result, numerical simulations are used to qualitatively capture the observed transient radiation response and provide insight into the physics of the induced current/voltages.« less

Probability Distribution of Dose and Dose-Rate Effectiveness Factor for use in Estimating Risks of Solid Cancers From Exposure to Low-Let Radiation.

PubMed

Kocher, David C; Apostoaei, A Iulian; Hoffman, F Owen; Trabalka, John R

2018-06-01

This paper presents an analysis to develop a subjective state-of-knowledge probability distribution of a dose and dose-rate effectiveness factor for use in estimating risks of solid cancers from exposure to low linear energy transfer radiation (photons or electrons) whenever linear dose responses from acute and chronic exposure are assumed. A dose and dose-rate effectiveness factor represents an assumption that the risk of a solid cancer per Gy at low acute doses or low dose rates of low linear energy transfer radiation, RL, differs from the risk per Gy at higher acute doses, RH; RL is estimated as RH divided by a dose and dose-rate effectiveness factor, where RH is estimated from analyses of dose responses in Japanese atomic-bomb survivors. A probability distribution to represent uncertainty in a dose and dose-rate effectiveness factor for solid cancers was developed from analyses of epidemiologic data on risks of incidence or mortality from all solid cancers as a group or all cancers excluding leukemias, including (1) analyses of possible nonlinearities in dose responses in atomic-bomb survivors, which give estimates of a low-dose effectiveness factor, and (2) comparisons of risks in radiation workers or members of the public from chronic exposure to low linear energy transfer radiation at low dose rates with risks in atomic-bomb survivors, which give estimates of a dose-rate effectiveness factor. Probability distributions of uncertain low-dose effectiveness factors and dose-rate effectiveness factors for solid cancer incidence and mortality were combined using assumptions about the relative weight that should be assigned to each estimate to represent its relevance to estimation of a dose and dose-rate effectiveness factor. The probability distribution of a dose and dose-rate effectiveness factor for solid cancers developed in this study has a median (50th percentile) and 90% subjective confidence interval of 1.3 (0.47, 3.6). The harmonic mean is 1.1, which implies that the arithmetic mean of an uncertain estimate of the risk of a solid cancer per Gy at low acute doses or low dose rates of low linear energy transfer radiation is only about 10% less than the mean risk per Gy at higher acute doses. Data were also evaluated to define a low acute dose or low dose rate of low linear energy transfer radiation, i.e., a dose or dose rate below which a dose and dose-rate effectiveness factor should be applied in estimating risks of solid cancers.

Simulation-Based Evaluation of Dose-Titration Algorithms for Rapid-Acting Insulin in Subjects with Type 2 Diabetes Mellitus Inadequately Controlled on Basal Insulin and Oral Antihyperglycemic Medications.

PubMed

Ma, Xiaosu; Chien, Jenny Y; Johnson, Jennal; Malone, James; Sinha, Vikram

2017-08-01

The purpose of this prospective, model-based simulation approach was to evaluate the impact of various rapid-acting mealtime insulin dose-titration algorithms on glycemic control (hemoglobin A1c [HbA1c]). Seven stepwise, glucose-driven insulin dose-titration algorithms were evaluated with a model-based simulation approach by using insulin lispro. Pre-meal blood glucose readings were used to adjust insulin lispro doses. Two control dosing algorithms were included for comparison: no insulin lispro (basal insulin+metformin only) or insulin lispro with fixed doses without titration. Of the seven dosing algorithms assessed, daily adjustment of insulin lispro dose, when glucose targets were met at pre-breakfast, pre-lunch, and pre-dinner, sequentially, demonstrated greater HbA1c reduction at 24 weeks, compared with the other dosing algorithms. Hypoglycemic rates were comparable among the dosing algorithms except for higher rates with the insulin lispro fixed-dose scenario (no titration), as expected. The inferior HbA1c response for the "basal plus metformin only" arm supports the additional glycemic benefit with prandial insulin lispro. Our model-based simulations support a simplified dosing algorithm that does not include carbohydrate counting, but that includes glucose targets for daily dose adjustment to maintain glycemic control with a low risk of hypoglycemia.

Antibiotic Dosing in Continuous Renal Replacement Therapy.

PubMed

Shaw, Alexander R; Mueller, Bruce A

2017-07-01

Appropriate antibiotic dosing is critical to improve outcomes in critically ill patients with sepsis. The addition of continuous renal replacement therapy makes achieving appropriate antibiotic dosing more difficult. The lack of continuous renal replacement therapy standardization results in treatment variability between patients and may influence whether appropriate antibiotic exposure is achieved. The aim of this study was to determine if continuous renal replacement therapy effluent flow rate impacts attaining appropriate antibiotic concentrations when conventional continuous renal replacement therapy antibiotic doses were used. This study used Monte Carlo simulations to evaluate the effect of effluent flow rate variance on pharmacodynamic target attainment for cefepime, ceftazidime, levofloxacin, meropenem, piperacillin, and tazobactam. Published demographic and pharmacokinetic parameters for each antibiotic were used to develop a pharmacokinetic model. Monte Carlo simulations of 5000 patients were evaluated for each antibiotic dosing regimen at the extremes of Kidney Disease: Improving Global Outcomes guidelines recommended effluent flow rates (20 and 35 mL/kg/h). The probability of target attainment was calculated using antibiotic-specific pharmacodynamic targets assessed over the first 72 hours of therapy. Most conventional published antibiotic dosing recommendations, except for levofloxacin, reach acceptable probability of target attainment rates when effluent rates of 20 or 35 mL/kg/h are used. Copyright © 2017 National Kidney Foundation, Inc. Published by Elsevier Inc. All rights reserved.

Nanocluster irradiation evolution in Fe-9%Cr ODS and ferritic-martensitic alloys

NASA Astrophysics Data System (ADS)

Swenson, M. J.; Wharry, J. P.

2017-12-01

The objective of this study is to evaluate the influence of dose rate and cascade morphology on nanocluster evolution in a model Fe-9%Cr oxide dispersion strengthened steel and the commercial ferritic/martensitic (F/M) alloys HCM12A and HT9. We present a large, systematic data set spanning the three alloys, three irradiating particle types, four orders of magnitude in dose rate, and doses ranging 1-100 displacements per atom over 400-500 °C. Nanoclusters are characterized using atom probe tomography. ODS oxide nanoclusters experience partial dissolution after irradiation due to inverse Ostwald ripening, while F/M nanoclusters undergo Ostwald ripening. Damage cascade morphology is indicative of nanocluster number density evolution. Finally, the effects of dose rate on nanocluster morphology provide evidence for a temperature dilation theory, which purports that a negative temperature shift is necessary for higher dose rate irradiations to emulate nanocluster evolution in lower dose rate irradiations.

Remanent dose rates around the collimators of the LHC beam cleaning insertions.

PubMed

Brugger, M; Roesler, S

2005-01-01

The LHC will require an extremely powerful and unprecedented collimation system. As approximately 30% of the LHC beam is lost in the cleaning insertions, these will become some of the most radioactive locations around the entire LHC ring. Thus, remanent dose rates to be expected during later repair or maintenance interventions must be considered in the design phase itself. As a consequence, the beam cleaning insertions form a unique test bed for a recently developed approach to calculate remanent dose rates. A set of simulations, different in complexity, is used in order to evaluate methods for the estimation of remanent dose rates. The scope, as well as the restrictions, of the omega-factor method are shown and compared with the explicit simulation approach. The latter is then used to calculate remanent dose rates in the beam cleaning insertions. Furthermore, a detailed example for maintenance dose planning is given.

Development of Safety Assessment Code for Decommissioning of Nuclear Facilities

NASA Astrophysics Data System (ADS)

Shimada, Taro; Ohshima, Soichiro; Sukegawa, Takenori

A safety assessment code, DecDose, for decommissioning of nuclear facilities has been developed, based on the experiences of the decommissioning project of Japan Power Demonstration Reactor (JPDR) at Japan Atomic Energy Research Institute (currently JAEA). DecDose evaluates the annual exposure dose of the public and workers according to the progress of decommissioning, and also evaluates the public dose at accidental situations including fire and explosion. As for the public, both the internal and the external doses are calculated by considering inhalation, ingestion, direct radiation from radioactive aerosols and radioactive depositions, and skyshine radiation from waste containers. For external dose for workers, the dose rate from contaminated components and structures to be dismantled is calculated. Internal dose for workers is calculated by considering dismantling conditions, e.g. cutting speed, cutting length of the components and exhaust velocity. Estimation models for dose rate and staying time were verified by comparison with the actual external dose of workers which were acquired during JPDR decommissioning project. DecDose code is expected to contribute the safety assessment for decommissioning of nuclear facilities.

Low-energy electron effects on tensile modulus and infrared transmission properties of a polypyromellitimide film

NASA Technical Reports Server (NTRS)

Ferl, J. E.; Long, E. R., Jr.

1981-01-01

Infrared (IR) spectroscopy and tensile modulus testing were used to evaluate the importance of experimental procedure on changes in properties of pyromellitic dianhydride-p,p prime-oxydianiline film exposed to electron radiation. The radiation exposures were accelerated, approximate equivalents to the total dose expected for a 30 year mission in geosynchronous Earth orbit. The change in the tensile modulus depends more on the dose rate and the time interval between exposure and testing than on total dose. The IR data vary with both total dose and dose rate. A threshold dose rate exists below which reversible radiation effects on the IR spectra occur. Above the threshold dose rate, irreversible effects occur with the appearance of a new band. Post-irradiation and in situ IR absorption bands are significantly different. It is suggested that the electron radiation induced metastable, excites molecular states.

Automatic optimisation of gamma dose rate sensor networks: The DETECT Optimisation Tool

NASA Astrophysics Data System (ADS)

Helle, K. B.; Müller, T. O.; Astrup, P.; Dyve, J. E.

2014-05-01

Fast delivery of comprehensive information on the radiological situation is essential for decision-making in nuclear emergencies. Most national radiological agencies in Europe employ gamma dose rate sensor networks to monitor radioactive pollution of the atmosphere. Sensor locations were often chosen using regular grids or according to administrative constraints. Nowadays, however, the choice can be based on more realistic risk assessment, as it is possible to simulate potential radioactive plumes. To support sensor planning, we developed the DETECT Optimisation Tool (DOT) within the scope of the EU FP 7 project DETECT. It evaluates the gamma dose rates that a proposed set of sensors might measure in an emergency and uses this information to optimise the sensor locations. The gamma dose rates are taken from a comprehensive library of simulations of atmospheric radioactive plumes from 64 source locations. These simulations cover the whole European Union, so the DOT allows evaluation and optimisation of sensor networks for all EU countries, as well as evaluation of fencing sensors around possible sources. Users can choose from seven cost functions to evaluate the capability of a given monitoring network for early detection of radioactive plumes or for the creation of dose maps. The DOT is implemented as a stand-alone easy-to-use JAVA-based application with a graphical user interface and an R backend. Users can run evaluations and optimisations, and display, store and download the results. The DOT runs on a server and can be accessed via common web browsers; it can also be installed locally.

Comparison Between Prospectively Electrocardiogram-Gated High-Pitch Mode and Retrospectively Electrocardiogram-Gated Mode for Dual-Source CT Coronary Angiography.

PubMed

Koplay, Mustafa; Celik, Mahmut; Avcı, Ahmet; Erdogan, Hasan; Demir, Kenan; Sivri, Mesut; Nayman, Alaaddin

2015-01-01

We aimed to report the image quality, relationship between heart rate and image quality, amount of contrast agent given to the patients and radiation doses in coronary CT angiography (CTA) obtained by using high-pitch prospectively ECG-gated "Flash Spiral" technique (method A) or retrospectively ECG-gated technique (method B) using 128×2-slice dual-source CT. A total of 110 patients who were evaluated with method A and method B technique with a 128×2-detector dual-source CT device were included in the study. Patients were divided into three groups based on their heart rates during the procedure, and a relationship between heart rate and image quality were evaluated. The relationship between heart rate, gender and radiation dose received by the patients was compared. A total of 1760 segments were evaluated in terms of image quality. Comparison of the relationship between heart rate and image quality revealed a significant difference between heart rate <60 beats/min group and >75 beats/min group whereas <60 beats/min and 60-75 beats/min groups did not differ significantly. The average effective dose for coronary CTA was calculated as 1.11 mSv (0.47-2.01 mSv) for method A and 8.22 mSv (2.19-12.88 mSv) for method B. Method A provided high quality images with doses as low as <1 mSv in selected patients who have low heart rates with a high negative predictive value to rule out coronary artery disease. Although method B increases the amount of effective dose, it provides high diagnostic quality images for patients who have a high heart rate and arrhythmia which makes it is difficult to obtain images.

Higher dose rate Gamma Knife radiosurgery may provide earlier and longer-lasting pain relief for patients with trigeminal neuralgia.

PubMed

Lee, John Y K; Sandhu, Sukhmeet; Miller, Denise; Solberg, Timothy; Dorsey, Jay F; Alonso-Basanta, Michelle

2015-10-01

Gamma Knife radiosurgery (GKRS) utilizes cobalt-60 as its radiation source, and thus dose rate varies as the fixed source decays over its half-life of approximately 5.26 years. This natural decay results in increasing treatment times when delivering the same cumulative dose. It is also possible, however, that the biological effective dose may change based on this dose rate even if the total dose is kept constant. Because patients are generally treated in a uniform manner, radiosurgery for trigeminal neuralgia (TN) represents a clinical model whereby biological efficacy can be tested. The authors hypothesized that higher dose rates would result in earlier and more complete pain relief but only if measured with a sensitive pain assessment tool. One hundred thirty-three patients were treated with the Gamma Knife Model 4C unit at a single center by a single neurosurgeon during a single cobalt life cycle from January 2006 to May 2012. All patients were treated with 80 Gy with a single 4-mm isocenter without blocking. Using an output factor of 0.87, dose rates ranged from 1.28 to 2.95 Gy/min. The Brief Pain Inventory (BPI)-Facial was administered before the procedure and at the first follow-up office visit 1 month from the procedure (mean 1.3 months). Phone calls were made to evaluate patients after their procedures as part of a retrospective study. Univariate and multivariate linear regression was performed on several independent variables, including sex, age in deciles, diagnosis, follow-up duration, prior surgery, and dose rate. In the short-term analysis (mean 1.3 months), patients' self-reported pain intensity at its worst was significantly correlated with dose rate on multivariate analysis (p = 0.028). Similarly, patients' self-reported interference with activities of daily living was closely correlated with dose rate on multivariate analysis (p = 0.067). A 1 Gy/min decrease in dose rate resulted in a 17% decrease in pain intensity at its worst and a 22% decrease in pain interference with activities of daily living. In longer-term follow-up (mean 1.9 years), GKRS with higher dose rates (> 2.0 Gy/min; p = 0.007) and older age in deciles (p = 0.012) were associated with a lower likelihood of recurrence of pain. Prior studies investigating the role of dose rate in Gamma Knife radiosurgical ablation for TN have not used validated outcome tools to measure pain preoperatively. Consequently, differences in pain outcomes have been difficult to measure. By administering pain scales both preoperatively as well as postoperatively, the authors have identified statistically significant differences in pain intensity and pain interference with activities of daily living when comparing higher versus lower dose rates. Radiosurgery with a higher dose rate results in more pain relief at the early follow-up evaluation, and it may result in a lower recurrence rate at later follow-up.

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

Assessment of ambient gamma dose rate around a prospective uranium mining area of South India - A comparative study of dose by direct methods and soil radioactivity measurements

NASA Astrophysics Data System (ADS)

Karunakara, N.; Yashodhara, I.; Sudeep Kumara, K.; Tripathi, R. M.; Menon, S. N.; Kadam, S.; Chougaonkar, M. P.

Indoor and outdoor gamma dose rates were evaluated around a prospective uranium mining region - Gogi, South India through (i) direct measurements using a GM based gamma dose survey meter, (ii) integrated measurement days using CaSO4:Dy based thermo luminescent dosimeters (TLDs), and (iii) analyses of 273 soil samples for 226Ra, 232Th, and 40K activity concentration using HPGe gamma spectrometry. The geometric mean values of indoor and outdoor gamma dose rates were 104 nGy h-1 and 97 nGy h-1, respectively with an indoor to outdoor dose ratio of 1.09. The gamma dose rates and activity concentrations of 226Ra, 232Th, and 40K varied significantly within a small area due to the highly localized mineralization of the elements. Correlation study showed that the dose estimated from the soil radioactivity is better correlated with that measured directly using the portable survey meter, when compared to that obtained from TLDs. This study showed that in a region having localized mineralization in situ measurements using dose survey meter provide better representative values of gamma dose rates.

An accurate derivation of the air dose-rate and the deposition concentration distribution by aerial monitoring in a low level contaminated area

NASA Astrophysics Data System (ADS)

Nishizawa, Yukiyasu; Sugita, Takeshi; Sanada, Yukihisa; Torii, Tatsuo

2015-04-01

Since 2011, MEXT (Ministry of Education, Culture, Sports, Science and Technology, Japan) have been conducting aerial monitoring to investigate the distribution of radioactive cesium dispersed into the atmosphere after the accident at the Fukushima Dai-ichi Nuclear Power Plant (FDNPP), Tokyo Electric Power Company. Distribution maps of the air dose-rate at 1 m above the ground and the radioactive cesium deposition concentration on the ground are prepared using spectrum obtained by aerial monitoring. The radioactive cesium deposition is derived from its dose rate, which is calculated by excluding the dose rate of the background radiation due to natural radionuclides from the air dose-rate at 1 m above the ground. The first step of the current method of calculating the dose rate due to natural radionuclides is calculate the ratio of the total count rate of areas where no radioactive cesium is detected and the count rate of regions with energy levels of 1,400 keV or higher (BG-Index). Next, calculate the air dose rate of radioactive cesium by multiplying the BG-Index and the integrated count rate of 1,400 keV or higher for the area where the radioactive cesium is distributed. In high dose-rate areas, however, the count rate of the 1,365-keV peak of Cs-134, though small, is included in the integrated count rate of 1,400 keV or higher, which could cause an overestimation of the air dose rate of natural radionuclides. We developed a method for accurately evaluating the distribution maps of natural air dose-rate by excluding the effect of radioactive cesium, even in contaminated areas, and obtained the accurate air dose-rate map attributed the radioactive cesium deposition on the ground. Furthermore, the natural dose-rate distribution throughout Japan has been obtained by this method.

Evaluation of indoor radon equilibrium factor using CFD modeling and resulting annual effective dose

NASA Astrophysics Data System (ADS)

Rabi, R.; Oufni, L.

2018-04-01

The equilibrium factor is an important parameter for reasonably estimating the population dose from radon. However, the equilibrium factor value depended mainly on the ventilation rate and the meteorological factors. Therefore, this study focuses on investigating numerically the influence of the ventilation rate, temperature and humidity on equilibrium factor between radon and its progeny. The numerical results showed that ventilation rate, temperature and humidity have significant impacts on indoor equilibrium factor. The variations of equilibrium factor with the ventilation, temperature and relative humidity are discussed. Moreover, the committed equivalent doses due to 218Po and 214Po radon short-lived progeny were evaluated in different tissues of the respiratory tract of the members of the public from the inhalation of indoor air. The annual effective dose due to radon short lived progeny from the inhalation of indoor air by the members of the public was investigated.

Characterization of the radiation environment at the UNLV accelerator facility during operation of the Varian M6 linac

NASA Astrophysics Data System (ADS)

Hodges, M.; Barzilov, A.; Chen, Y.; Lowe, D.

2016-10-01

The bremsstrahlung photon flux from the UNLV particle accelerator (Varian M6 model) was determined using MCNP5 code for 3 MeV and 6 MeV incident electrons. Human biological equivalent dose rates due to accelerator operation were evaluated using the photon flux with the flux-to-dose conversion factors. Dose rates were computed for the accelerator facility for M6 linac use under different operating conditions. The results showed that the use of collimators and linac internal shielding significantly reduced the dose rates throughout the facility. It was shown that the walls of the facility, in addition to the earthen berm enveloping the building, provide equivalent shielding to reduce dose rates outside to below the 2 mrem/h limit.

SU-E-T-538: Evaluation of IMRT Dose Calculation Based on Pencil-Beam and AAA Algorithms.

PubMed

Yuan, Y; Duan, J; Popple, R; Brezovich, I

2012-06-01

To evaluate the accuracy of dose calculation for intensity modulated radiation therapy (IMRT) based on Pencil Beam (PB) and Analytical Anisotropic Algorithm (AAA) computation algorithms. IMRT plans of twelve patients with different treatment sites, including head/neck, lung and pelvis, were investigated. For each patient, dose calculation with PB and AAA algorithms using dose grid sizes of 0.5 mm, 0.25 mm, and 0.125 mm, were compared with composite-beam ion chamber and film measurements in patient specific QA. Discrepancies between the calculation and the measurement were evaluated by percentage error for ion chamber dose and γ〉l failure rate in gamma analysis (3%/3mm) for film dosimetry. For 9 patients, ion chamber dose calculated with AAA-algorithms is closer to ion chamber measurement than that calculated with PB algorithm with grid size of 2.5 mm, though all calculated ion chamber doses are within 3% of the measurements. For head/neck patients and other patients with large treatment volumes, γ〉l failure rate is significantly reduced (within 5%) with AAA-based treatment planning compared to generally more than 10% with PB-based treatment planning (grid size=2.5 mm). For lung and brain cancer patients with medium and small treatment volumes, γ〉l failure rates are typically within 5% for both AAA and PB-based treatment planning (grid size=2.5 mm). For both PB and AAA-based treatment planning, improvements of dose calculation accuracy with finer dose grids were observed in film dosimetry of 11 patients and in ion chamber measurements for 3 patients. AAA-based treatment planning provides more accurate dose calculation for head/neck patients and other patients with large treatment volumes. Compared with film dosimetry, a γ〉l failure rate within 5% can be achieved for AAA-based treatment planning. © 2012 American Association of Physicists in Medicine.

Accelerated Irradiations for High Dose Microstructures in Fast Reactor Alloys

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

Jiao, Zhijie

The objective of this project is to determine the extent to which high dose rate, self-ion irradiation can be used as an accelerated irradiation tool to understand microstructure evolution at high doses and temperatures relevant to advanced fast reactors. We will accomplish the goal by evaluating phase stability and swelling of F-M alloys relevant to SFR systems at very high dose by combining experiment and modeling in an effort to obtain a quantitative description of the processes at high and low damage rates.

A new approach using coagulation rate constant for evaluation of turbidity removal

NASA Astrophysics Data System (ADS)

Al-Sameraiy, Mukheled

2017-06-01

Coagulation-flocculation-sedimentation processes for treating three levels of bentonite synthetic turbid water using date seeds (DS) and alum (A) coagulants were investigated in the previous research work. In the current research, the same experimental results were used to adopt a new approach on a basis of using coagulation rate constant as an investigating parameter to identify optimum doses of these coagulants. Moreover, the performance of these coagulants to meet (WHO) turbidity standard was assessed by introducing a new evaluating criterion in terms of critical coagulation rate constant (kc). Coagulation rate constants (k2) were mathematically calculated in second order form of coagulation process for each coagulant. The maximum (k2) values corresponded to doses, which were obviously to be considered as optimum doses. The proposed criterion to assess the performance of coagulation process of these coagulants was based on the mathematical representation of (WHO) turbidity guidelines in second order form of coagulation process stated that (k2) for each coagulant should be ≥ (kc) for each level of synthetic turbid water. For all tested turbid water, DS coagulant could not satisfy it. While, A coagulant could satisfy it. The results obtained in the present research are exactly in agreement with the previous published results in terms of finding optimum doses for each coagulant and assessing their performances. On the whole, it is recommended considering coagulation rate constant to be a new approach as an indicator for investigating optimum doses and critical coagulation rate constant to be a new evaluating criterion to assess coagulants' performance.

The Impact of Dose Rate on the Accuracy of Step-and-Shoot Intensity-modulated Radiation Therapy Quality Assurance Using Varian 2300CD.

PubMed

Njeh, Christopher F; Salmon, Howard W; Schiller, Claire

2017-01-01

Intensity-modulated radiation therapy (IMRT) delivery using "step-and-shoot" technique on Varian C-Series linear accelerator (linac) is influenced by the communication frequency between the multileaf collimator and linac controllers. Hence, the dose delivery accuracy is affected by the dose rate. Our aim was to quantify the impact of using two dose rates on plan quality assurance (QA). Twenty IMRT patients were selected for this study. The plan QA was measured at two different dose rates. A gamma analysis was performed, and the degree of plan modulation on the QA pass rate was also evaluated in terms of average monitor unit per segment (MU/segment) and the total number of segments. The mean percentage gamma pass rate of 94.9% and 93.5% for 300 MU/min and 600 MU/min dose rate, respectively, was observed. There was a significant ( P = 0.001) decrease in percentage gamma pass rate when the dose rate was increased from 300 MU/min to 600 MU/min. There was a weak, but significant association between the percentage pass rate at both dose rate and total number of segments. The total number of MU was significantly correlated to the total number of segments ( r = 0.59). We found a positive correlation between the percentage pass rate and mean MU/segment, r = 0.52 and r = 0.57 for 300 MU/min and 600 MU/min, respectively. IMRT delivery using step-and-shoot technique on Varian 2300CD is impacted by the dose rate and the total amount of segments.

Dose rate dependence for different dosimeters and detectors: TLD, OSL, EBT films, and diamond detectors.

PubMed

Karsch, L; Beyreuther, E; Burris-Mog, T; Kraft, S; Richter, C; Zeil, K; Pawelke, J

2012-05-01

The use of laser accelerators in radiation therapy can perhaps increase the low number of proton and ion therapy facilities in some years due to the low investment costs and small size. The laser-based acceleration technology leads to a very high peak dose rate of about 10(11) Gy∕s. A first dosimetric task is the evaluation of dose rate dependence of clinical dosimeters and other detectors. The measurements were done at ELBE, a superconductive linear electron accelerator which generates electron pulses with 5 ps length at 20 MeV. The different dose rates are reached by adjusting the number of electrons in one beam pulse. Three clinical dosimeters (TLD, OSL, and EBT radiochromic films) were irradiated with four different dose rates and nearly the same dose. A faraday cup, an integrating current transformer, and an ionization chamber were used to control the particle flux on the dosimeters. Furthermore two diamond detectors were tested. The dosimeters are dose rate independent up to 4●10(9) Gy∕s within 2% (OSL and TLD) and up to 15●10(9) Gy∕s within 5% (EBT films). The diamond detectors show strong dose rate dependence. TLD, OSL dosimeters, and EBT films are suitable for pulsed beams with a very high pulse dose rate like laser accelerated particle beams.

Dose rate dependence for different dosimeters and detectors: TLD, OSL, EBT films, and diamond detectors

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

Karsch, L.; Beyreuther, E.; Burris-Mog, T.

Purpose: The use of laser accelerators in radiation therapy can perhaps increase the low number of proton and ion therapy facilities in some years due to the low investment costs and small size. The laser-based acceleration technology leads to a very high peak dose rate of about 10{sup 11} Gy/s. A first dosimetric task is the evaluation of dose rate dependence of clinical dosimeters and other detectors. Methods: The measurements were done at ELBE, a superconductive linear electron accelerator which generates electron pulses with 5 ps length at 20 MeV. The different dose rates are reached by adjusting the numbermore » of electrons in one beam pulse. Three clinical dosimeters (TLD, OSL, and EBT radiochromic films) were irradiated with four different dose rates and nearly the same dose. A faraday cup, an integrating current transformer, and an ionization chamber were used to control the particle flux on the dosimeters. Furthermore two diamond detectors were tested. Results: The dosimeters are dose rate independent up to 410{sup 9} Gy/s within 2% (OSL and TLD) and up to 1510{sup 9} Gy/s within 5% (EBT films). The diamond detectors show strong dose rate dependence. Conclusions: TLD, OSL dosimeters, and EBT films are suitable for pulsed beams with a very high pulse dose rate like laser accelerated particle beams.« less

Measurement of ambient dose equivalent rates by walk survey around Fukushima Dai-ichi Nuclear Power Plant using KURAMA-II until 2016.

PubMed

Andoh, Masaki; Yamamoto, Hideaki; Kanno, Takashi; Saito, Kimiaki

2018-05-17

Ambient dose equivalent rates in various environments related to human lives were measured by walk surveys using the KURAMA-II systems from 2013 to 2016 within an 80-km radius of the Fukushima Dai-ichi Nuclear Power Plant. The dose rate of the locations where the walk survey was performed decreased to about 38% of its initial value in the 42 months from June 2013 to the December 2016, which was beyond that attributable to the physical decay of radiocaesium. The ecological half-life of the slow decreasing component was evaluated to be 4.1 ± 0.2 y. The air dose rates decreased depending on the level of the evacuation areas, and the decrease in the dose rates was slightly larger in populated areas where humans are active. The dose rates as measured by walk surveys exhibited a good correlation with those by car-borne surveys, suggesting that car-borne survey data are reflecting the air dose rates in living environments surrounding roads. The comparison of walk survey data with car-borne survey data indicated that the air dose rate varies largely even within a 100 m square area, and the variation is enhanced by human activities. The dose rates measured by the walk surveys were estimated to be medial of those along roads and those of undisturbed flat ground, and they were found to be decreasing quickly compared with the air dose rate from the flat ground fixed-point measurements. Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.

Effective dose rate coefficients for exposure to contaminated soil

DOE PAGES

Veinot, Kenneth G.; Eckerman, Keith F.; Bellamy, Michael B.; ...

2017-05-10

The Oak Ridge National Laboratory Center for Radiation Protection Knowledge has undertaken calculations related to various environmental exposure scenarios. A previous paper reported the results for submersion in radioactive air and immersion in water using age-specific mathematical phantoms. This paper presents age-specific effective dose rate coefficients derived using stylized mathematical phantoms for exposure to contaminated soils. Dose rate coefficients for photon, electron, and positrons of discrete energies were calculated and folded with emissions of 1252 radionuclides addressed in ICRP Publication 107 to determine equivalent and effective dose rate coefficients. The MCNP6 radiation transport code was used for organ dose ratemore » calculations for photons and the contribution of electrons to skin dose rate was derived using point-kernels. Bremsstrahlung and annihilation photons of positron emission were evaluated as discrete photons. As a result, the coefficients calculated in this work compare favorably to those reported in the US Federal Guidance Report 12 as well as by other authors who employed voxel phantoms for similar exposure scenarios.« less

Effective dose rate coefficients for exposure to contaminated soil

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

Veinot, Kenneth G.; Eckerman, Keith F.; Bellamy, Michael B.

The Oak Ridge National Laboratory Center for Radiation Protection Knowledge has undertaken calculations related to various environmental exposure scenarios. A previous paper reported the results for submersion in radioactive air and immersion in water using age-specific mathematical phantoms. This paper presents age-specific effective dose rate coefficients derived using stylized mathematical phantoms for exposure to contaminated soils. Dose rate coefficients for photon, electron, and positrons of discrete energies were calculated and folded with emissions of 1252 radionuclides addressed in ICRP Publication 107 to determine equivalent and effective dose rate coefficients. The MCNP6 radiation transport code was used for organ dose ratemore » calculations for photons and the contribution of electrons to skin dose rate was derived using point-kernels. Bremsstrahlung and annihilation photons of positron emission were evaluated as discrete photons. As a result, the coefficients calculated in this work compare favorably to those reported in the US Federal Guidance Report 12 as well as by other authors who employed voxel phantoms for similar exposure scenarios.« less

Dose and dose rate effects of whole-body gamma-irradiation: II. Hematological variables and cytokines

NASA Technical Reports Server (NTRS)

Gridley, D. S.; Pecaut, M. J.; Miller, G. M.; Moyers, M. F.; Nelson, G. A.

2001-01-01

The goal of part II of this study was to evaluate the effects of gamma-radiation on circulating blood cells, functional characteristics of splenocytes, and cytokine expression after whole-body irradiation at varying total doses and at low- and high-dose-rates (LDR, HDR). Young adult C57BL/6 mice (n = 75) were irradiated with either 1 cGy/min or 80 cGy/min photons from a 60Co source to cumulative doses of 0.5, 1.5, and 3.0 Gy. The animals were euthanized at 4 days post-exposure for in vitro assays. Significant dose- (but not dose-rate-) dependent decreases were observed in erythrocyte and blood leukocyte counts, hemoglobin, hematocrit, lipopolysaccharide (LPS)-induced 3H-thymidine incorporation, and interleukin-2 (IL-2) secretion by activated spleen cells when compared to sham-irradiated controls (p < 0.05). Basal proliferation of leukocytes in the blood and spleen increased significantly with increasing dose (p < 0.05). Significant dose rate effects were observed only in thrombocyte counts. Plasma levels of transforming growth factor-beta 1 (TGF-beta 1) and splenocyte secretion of tumor necrosis factor-alpha (TNF-alpha) were not affected by either the dose or dose rate of radiation. The data demonstrate that the responses of blood and spleen were largely dependent upon the total dose of radiation employed and that an 80-fold difference in the dose rate was not a significant factor in the great majority of measurements.

Immunogenicity and safety of 1 vs 2 doses of quadrivalent meningococcal conjugate vaccine in youth infected with human immunodeficiency virus.

PubMed

Lujan-Zilbermann, Jorge; Warshaw, Meredith G; Williams, Paige L; Spector, Stephen A; Decker, Michael D; Abzug, Mark J; Heckman, Barb; Manzella, Adam; Kabat, Bill; Jean-Philippe, Patrick; Nachman, Sharon; Siberry, George K

2012-10-01

To compare the immunogenicity of 1 vs 2 doses of meningococcal polysaccharide conjugate vaccine (MCV4) in youth infected with human immunodeficiency virus (HIV). P1065 was a phase I/II immunogenicity and safety trial of MCV4 in 324 youth infected with HIV performed at 27 sites of the International Maternal Pediatric Adolescent AIDS Clinical Trials Group network in the US. At entry subjects received 1 dose of MCV4. At 24 weeks, those with screening cluster of differentiation 4 (CD4)% ≥ 15 were randomized to receive a second dose or not, and all with screening CD4% <15 received a second dose. Immunogenicity was evaluated as the proportion of subjects with a ≥ 4-fold rise from entry in serum bactericidal antibody against each meningococcal serogroup (SG) at weeks 28 and 72. Logistic regression models adjusting for HIV disease severity were used to evaluate the effect of 1 vs 2 MCV4 doses among those with screening CD4% ≥ 15. Subjects randomized to receive 2 vs 1 MCV4 dose had significantly higher response rates to all SGs at week 28 and to all except Neisseria meningitidis SG Y at week 72, with adjusted ORs of 2.5-5.6. In 31 subjects with screening CD4% <15 who received 2 MCV4 doses, response rates ranged from 22%-55% at week 28 and 6%-28% at week 72. In youth infected with HIV with a CD4% ≥ 15, a second dose of MCV4 given 6 months after the initial dose significantly improves response rates at 28 and 72 weeks. Subjects with CD4% <15 at entry had lower response rates despite 2 doses of MCV4. Copyright © 2012 Mosby, Inc. All rights reserved.

Feasibility of using two-dimensional array dosimeter for in vivo dose reconstruction via transit dosimetry.

PubMed

Chung, Heeteak; Li, Jonathan; Samant, Sanjiv

2011-04-08

Two-dimensional array dosimeters are commonly used to perform pretreatment quality assurance procedures, which makes them highly desirable for measuring transit fluences for in vivo dose reconstruction. The purpose of this study was to determine if an in vivo dose reconstruction via transit dosimetry using a 2D array dosimeter was possible. To test the accuracy of measuring transit dose distribution using a 2D array dosimeter, we evaluated it against the measurements made using ionization chamber and radiochromic film (RCF) profiles for various air gap distances (distance from the exit side of the solid water slabs to the detector distance; 0 cm, 30 cm, 40 cm, 50 cm, and 60 cm) and solid water slab thicknesses (10 cm and 20 cm). The backprojection dose reconstruction algorithm was described and evaluated. The agreement between the ionization chamber and RCF profiles for the transit dose distribution measurements ranged from -0.2% ~ 4.0% (average 1.79%). Using the backprojection dose reconstruction algorithm, we found that, of the six conformal fields, four had a 100% gamma index passing rate (3%/3 mm gamma index criteria), and two had gamma index passing rates of 99.4% and 99.6%. Of the five IMRT fields, three had a 100% gamma index passing rate, and two had gamma index passing rates of 99.6% and 98.8%. It was found that a 2D array dosimeter could be used for backprojection dose reconstruction for in vivo dosimetry.

Acceleration of atherogenesis in ApoE-/- mice exposed to acute or low-dose-rate ionizing radiation.

PubMed

Mancuso, Mariateresa; Pasquali, Emanuela; Braga-Tanaka, Ignacia; Tanaka, Satoshi; Pannicelli, Alessandro; Giardullo, Paola; Pazzaglia, Simonetta; Tapio, Soile; Atkinson, Michael J; Saran, Anna

2015-10-13

There is epidemiological evidence for increased non-cancer mortality, primarily due to circulatory diseases after radiation exposure above 0.5 Sv. We evaluated the effects of chronic low-dose rate versus acute exposures in a murine model of spontaneous atherogenesis. Female ApoE-/- mice (60 days) were chronically irradiated for 300 days with gamma rays at two different dose rates (1 mGy/day; 20 mGy/day), with total accumulated doses of 0.3 or 6 Gy. For comparison, age-matched ApoE-/- females were acutely exposed to the same doses and sacrificed 300 days post-irradiation. Mice acutely exposed to 0.3 or 6 Gy showed increased atherogenesis compared to age-matched controls, and this effect was persistent. When the same doses were delivered at low dose rate over 300 days, we again observed a significant impact on global development of atherosclerosis, although at 0.3 Gy effects were limited to the descending thoracic aorta. Our data suggest that a moderate dose of 0.3 Gy can have persistent detrimental effects on the cardiovascular system, and that a high dose of 6 Gy poses high risks at both high and low dose rates. Our results were clearly nonlinear with dose, suggesting that lower doses may be more damaging than predicted by a linear dose response.

Characterization and clinical evaluation of a novel 2D detector array for conventional and flattening filter free (FFF) IMRT pre-treatment verification.

PubMed

Sekar, Yuvaraj; Thoelking, Johannes; Eckl, Miriam; Kalichava, Irakli; Sihono, Dwi Seno Kuncoro; Lohr, Frank; Wenz, Frederik; Wertz, Hansjoerg

2018-04-01

The novel MatriXX FFF (IBA Dosimetry, Germany) detector is a new 2D ionization chamber detector array designed for patient specific IMRT-plan verification including flattening-filter-free (FFF) beams. This study provides a detailed analysis of the characterization and clinical evaluation of the new detector array. The verification of the MatriXX FFF was subdivided into (i) physical dosimetric tests including dose linearity, dose rate dependency and output factor measurements and (ii) patient specific IMRT pre-treatment plan verifications. The MatriXX FFF measurements were compared to the calculated dose distribution of a commissioned treatment planning system by gamma index and dose difference evaluations for 18 IMRT-sequences. All IMRT-sequences were measured with original gantry angles and with collapsing all beams to 0° gantry angle to exclude the influence of the detector's angle dependency. The MatriXX FFF was found to be linear and dose rate independent for all investigated modalities (deviations ≤0.6%). Furthermore, the output measurements of the MatriXX FFF were in very good agreement to reference measurements (deviations ≤1.8%). For the clinical evaluation an average pixel passing rate for γ (3%,3mm) of (98.5±1.5)% was achieved when applying a gantry angle correction. Also, with collapsing all beams to 0° gantry angle an excellent agreement to the calculated dose distribution was observed (γ (3%,3mm) =(99.1±1.1)%). The MatriXX FFF fulfills all physical requirements in terms of dosimetric accuracy. Furthermore, the evaluation of the IMRT-plan measurements showed that the detector particularly together with the gantry angle correction is a reliable device for IMRT-plan verification including FFF. Copyright © 2017. Published by Elsevier GmbH.

Development and Evaluation of a New Air Exchange Rate Algorithm for the Stochastic Human Exposure and Dose Simulation Model

EPA Science Inventory

between-home and between-city variability in residential pollutant infiltration. This is likely a result of differences in home ventilation, or air exchange rates (AER). The Stochastic Human Exposure and Dose Simulation (SHEDS) model is a population exposure model that uses a pro...

Effects of gamma irradiation dose-rate on sterile male Aedesaegypti

NASA Astrophysics Data System (ADS)

Ernawan, Beni; Tambunan, Usman Sumo Friend; Sugoro, Irawan; Sasmita, Hadian Iman

2017-06-01

Aedesaegypti is the most important vector for dengue, yellow fever and Zika viruses. Considering its medical importance, vector population control program utilizing radiation-based sterile insect technique (SIT) is one of the potential methods for preventing and limiting the dispersal of these viruses. The present study was undertaken to evaluate the dose-rates effects of γ-sterilization on quality parameters of sterile males. Males Ae.aegypti at the pupal stage were sterilized by applying 70 Gyγ-rays in varies dose-rates, i.e. 0 (control), 300, 600, 900, 1200 and 1500Gy/h utilizing panoramic irradiator. Adult males that emerged from the pupal stage were assessed for their quality parameters, which are the percentage of emergence, longevity, sterility and mating competitiveness. The results herein indicate that there was no major effect of dose-rate on the percentage of emergence, the data showedthat there were no differences between irradiated males compared with control. Generally, the longevity of irradiated males was lower compared to control. The data also demonstrated that longevity was significantly increased at the dose-rate from 300 to 900Gy/h, then decreased at the dose-rate 900 to 1500 Gy/h. Sterility of irradiated maleswas significantly different compared to control, while there was no significantly different at dose rate 300 to 1500 Gy/h. Mating competitiveness of irradiated males was increased at the dose rate from 300 to 1200 Gy/h, then the value was decreased significantly at the dose rate 1500 Gy/h. The dose-rate effects of γ-sterilization were discussed in the context genetic vector control, in particular, the SIT. The results give information and contribute to better understanding towards γ-sterilization optimization and quality parameters of sterile male Ae. aegypti on SIT methods.

Dose and dose rate effects of whole-body proton-irradiation on lymphocyte blastogenesis and hematological variables: part II

NASA Technical Reports Server (NTRS)

Pecaut, Michael J.; Gridley, Daila S.; Smith, Anna L.; Nelson, Gregory A.

2002-01-01

The goal of part II of this study was to evaluate functional characteristics of leukocytes and circulating blood cell parameters after whole-body proton irradiation at varying doses and at low- and high-dose-rates (LDR and HDR, respectively). C57BL/6 mice (n=51) were irradiated and euthanized at 4 days post-exposure for assay. Significant radiation dose- (but not dose-rate-) dependent decreases were observed in splenocyte responses to T and B cell mitogens when compared to sham-irradiated controls (P<0.001). Spontaneous blastogenesis, also significantly dose-dependent, was increased in both blood and spleen (P<0.001). Red blood cell counts, hemoglobin concentration, and hematocrit were decreased in a dose-dependent manner (P<0.05), whereas thrombocyte numbers were only slightly affected. Comparison of proton- and gamma-irradiated groups (both receiving 3 Gy at HDR) showed a higher level of spontaneous blastogenesis in blood leukocytes and a lower splenocyte response to concanavalin A following proton irradiation (P<0.05). There were no dose rate effects. Collectively, the data demonstrate that the measurements in blood and spleen were largely dependent upon the total dose of proton radiation and that an 80-fold difference in the dose rate was not a significant factor. A difference, however, was found between protons and gamma-rays in the degree of change induced in some of the measurements.

Cost-effectiveness of allopurinol and febuxostat for the management of gout.

PubMed

Jutkowitz, Eric; Choi, Hyon K; Pizzi, Laura T; Kuntz, Karen M

2014-11-04

Gout is the most common inflammatory arthritis in the United States. To evaluate the cost-effectiveness of urate-lowering treatment strategies for the management of gout. Markov model. Published literature and expert opinion. Patients for whom allopurinol or febuxostat is a suitable initial urate-lowering treatment. Lifetime. Health care payer. 5 urate-lowering treatment strategies were evaluated: no treatment; allopurinol- or febuxostat-only therapy; allopurinol-febuxostat sequential therapy; and febuxostat-allopurinol sequential therapy. Two dosing scenarios were investigated: fixed dose (80 mg of febuxostat daily, 0.80 success rate; 300 mg of allopurinol daily, 0.39 success rate) and dose escalation (≤120 mg of febuxostat daily, 0.82 success rate; ≤800 mg of allopurinol daily, 0.78 success rate). Discounted costs, discounted quality-adjusted life-years, and incremental cost-effectiveness ratios. In both dosing scenarios, allopurinol-only therapy was cost-saving. Dose-escalation allopurinol-febuxostat sequential therapy was more costly but more effective than dose-escalation allopurinol therapy, with an incremental cost-effectiveness ratio of $39 400 per quality-adjusted life-year. The relative rankings of treatments did not change. Our results were relatively sensitive to several potential variations of model assumptions; however, the cost-effectiveness ratios of dose escalation with allopurinol-febuxostat sequential therapy remained lower than the willingness-to-pay threshold of $109 000 per quality-adjusted life-year. Long-term outcome data for patients with gout, including medication adherence, are limited. Allopurinol single therapy is cost-saving compared with no treatment. Dose-escalation allopurinol-febuxostat sequential therapy is cost-effective compared with accepted willingness-to-pay thresholds. Agency for Healthcare Research and Quality.

Feasibility of using two‐dimensional array dosimeter for in vivo dose reconstruction via transit dosimetry

PubMed Central

Li, Jonathan; Samant, Sanjiv

2011-01-01

Two‐dimensional array dosimeters are commonly used to perform pretreatment quality assurance procedures, which makes them highly desirable for measuring transit fluences for in vivo dose reconstruction. The purpose of this study was to determine if an in vivo dose reconstruction via transit dosimetry using a 2D array dosimeter was possible. To test the accuracy of measuring transit dose distribution using a 2D array dosimeter, we evaluated it against the measurements made using ionization chamber and radiochromic film (RCF) profiles for various air gap distances (distance from the exit side of the solid water slabs to the detector distance; 0 cm, 30 cm, 40 cm, 50 cm, and 60 cm) and solid water slab thicknesses (10 cm and 20 cm). The backprojection dose reconstruction algorithm was described and evaluated. The agreement between the ionization chamber and RCF profiles for the transit dose distribution measurements ranged from ‐0.2%~ 4.0% (average 1.79%). Using the backprojection dose reconstruction algorithm, we found that, of the six conformal fields, four had a 100% gamma index passing rate (3%/3 mm gamma index criteria), and two had gamma index passing rates of 99.4% and 99.6%. Of the five IMRT fields, three had a 100% gamma index passing rate, and two had gamma index passing rates of 99.6% and 98.8%. It was found that a 2D array dosimeter could be used for backprojection dose reconstruction for in vivo dosimetry. PACS number: 87.55.N‐

Radiation Parameters of High Dose Rate Iridium -192 Sources

NASA Astrophysics Data System (ADS)

Podgorsak, Matthew B.

A lack of physical data for high dose rate (HDR) Ir-192 sources has necessitated the use of basic radiation parameters measured with low dose rate (LDR) Ir-192 seeds and ribbons in HDR dosimetry calculations. A rigorous examination of the radiation parameters of several HDR Ir-192 sources has shown that this extension of physical data from LDR to HDR Ir-192 may be inaccurate. Uncertainty in any of the basic radiation parameters used in dosimetry calculations compromises the accuracy of the calculated dose distribution and the subsequent dose delivery. Dose errors of up to 0.3%, 6%, and 2% can result from the use of currently accepted values for the half-life, exposure rate constant, and dose buildup effect, respectively. Since an accuracy of 5% in the delivered dose is essential to prevent severe complications or tumor regrowth, the use of basic physical constants with uncertainties approaching 6% is unacceptable. A systematic evaluation of the pertinent radiation parameters contributes to a reduction in the overall uncertainty in HDR Ir-192 dose delivery. Moreover, the results of the studies described in this thesis contribute significantly to the establishment of standardized numerical values to be used in HDR Ir-192 dosimetry calculations.

SU-F-P-39: End-To-End Validation of a 6 MV High Dose Rate Photon Beam, Configured for Eclipse AAA Algorithm Using Golden Beam Data, for SBRT Treatments Using RapidArc

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

Ferreyra, M; Salinas Aranda, F; Dodat, D

Purpose: To use end-to-end testing to validate a 6 MV high dose rate photon beam, configured for Eclipse AAA algorithm using Golden Beam Data (GBD), for SBRT treatments using RapidArc. Methods: Beam data was configured for Varian Eclipse AAA algorithm using the GBD provided by the vendor. Transverse and diagonals dose profiles, PDDs and output factors down to a field size of 2×2 cm2 were measured on a Varian Trilogy Linac and compared with GBD library using 2% 2mm 1D gamma analysis. The MLC transmission factor and dosimetric leaf gap were determined to characterize the MLC in Eclipse. Mechanical andmore » dosimetric tests were performed combining different gantry rotation speeds, dose rates and leaf speeds to evaluate the delivery system performance according to VMAT accuracy requirements. An end-to-end test was implemented planning several SBRT RapidArc treatments on a CIRS 002LFC IMRT Thorax Phantom. The CT scanner calibration curve was acquired and loaded in Eclipse. PTW 31013 ionization chamber was used with Keithley 35617EBS electrometer for absolute point dose measurements in water and lung equivalent inserts. TPS calculated planar dose distributions were compared to those measured using EPID and MapCheck, as an independent verification method. Results were evaluated with gamma criteria of 2% dose difference and 2mm DTA for 95% of points. Results: GBD set vs. measured data passed 2% 2mm 1D gamma analysis even for small fields. Machine performance tests show results are independent of machine delivery configuration, as expected. Absolute point dosimetry comparison resulted within 4% for the worst case scenario in lung. Over 97% of the points evaluated in dose distributions passed gamma index analysis. Conclusion: Eclipse AAA algorithm configuration of the 6 MV high dose rate photon beam using GBD proved efficient. End-to-end test dose calculation results indicate it can be used clinically for SBRT using RapidArc.« less

Evaluation of the Environmental Gamma-ray Dose Rate by Skyshine Analysis During the Maintenance of an Activated TFC in ITER

NASA Astrophysics Data System (ADS)

Sato, S.; Takatsu, H.; Maki, K.; Yamada, K.; Mori, S.; Iida, H.; Santoro, R. T.

1997-09-01

Gamma-ray exposure dose rates at the ITER site boundary were estimated for the cases of removal of a failed activated Toroidal Field (TF) coil from the torus and removal of a failed activated TF coil together with a sector of the activated Vacuum Vessel (VV). Skyshine analyses were performed using the two-dimensional SN radiation transport code, DOT3.5. The exposure gamma-ray dose rates on the ground at the site boundary (presently assumed to be 1 km from the ITER building), were calculated to be 1.1 and 84 μSv/year for removal of the TF coil without and with a VV sector, respectively. The dose rate level for the latter case is close to the tentative radiation limit of 100 μSv/year so an additional ˜14 cm of concrete is required in the ITER building roof to satisfy the criterion for a safety factor often for the site boundary dose rate.

A Comparison of Dose-Response Models for the Parotid Gland in a Large Group of Head-and-Neck Cancer Patients

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

Houweling, Antonetta C., E-mail: A.Houweling@umcutrecht.n; Philippens, Marielle E.P.; Dijkema, Tim

2010-03-15

Purpose: The dose-response relationship of the parotid gland has been described most frequently using the Lyman-Kutcher-Burman model. However, various other normal tissue complication probability (NTCP) models exist. We evaluated in a large group of patients the value of six NTCP models that describe the parotid gland dose response 1 year after radiotherapy. Methods and Materials: A total of 347 patients with head-and-neck tumors were included in this prospective parotid gland dose-response study. The patients were treated with either conventional radiotherapy or intensity-modulated radiotherapy. Dose-volume histograms for the parotid glands were derived from three-dimensional dose calculations using computed tomography scans. Stimulatedmore » salivary flow rates were measured before and 1 year after radiotherapy. A threshold of 25% of the pretreatment flow rate was used to define a complication. The evaluated models included the Lyman-Kutcher-Burman model, the mean dose model, the relative seriality model, the critical volume model, the parallel functional subunit model, and the dose-threshold model. The goodness of fit (GOF) was determined by the deviance and a Monte Carlo hypothesis test. Ranking of the models was based on Akaike's information criterion (AIC). Results: None of the models was rejected based on the evaluation of the GOF. The mean dose model was ranked as the best model based on the AIC. The TD{sub 50} in these models was approximately 39 Gy. Conclusions: The mean dose model was preferred for describing the dose-response relationship of the parotid gland.« less

Radiation dose distributions due to sudden ejection of cobalt device.

PubMed

Abdelhady, Amr

2016-09-01

The evaluation of the radiation dose during accident in a nuclear reactor is of great concern from the viewpoint of safety. One of important accident must be analyzed and may be occurred in open pool type reactor is the rejection of cobalt device. The study is evaluating the dose rate levels resulting from upset withdrawal of co device especially the radiation dose received by the operator in the control room. Study of indirect radiation exposure to the environment due to skyshine effect is also taken into consideration in order to evaluate the radiation dose levels around the reactor during the ejection trip. Microshield, SHLDUTIL, and MCSky codes were used in this study to calculate the radiation dose profiles during cobalt device ejection trip inside and outside the reactor building. Copyright © 2016 Elsevier Ltd. All rights reserved.

Application of a color scanner for 60Co high dose rate brachytherapy dosimetry with EBT radiochromic film

PubMed Central

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

2012-01-01

Background. The aim of this study is to evaluate the performance of a color scanner as a radiochromic film reader in two dimensional dosimetry around a high dose rate brachytherapy source. Materials and methods A Microtek ScanMaker 1000XL film scanner was utilized for the measurement of dose distribution around a high dose rate GZP6 60Co brachytherapy source with GafChromic® EBT radiochromic films. In these investigations, the non-uniformity of the film and scanner response, combined, as well as the films sensitivity to scanner’s light source was evaluated using multiple samples of films, prior to the source dosimetry. The results of these measurements were compared with the Monte Carlo simulated data using MCNPX code. In addition, isodose curves acquired by radiochromic films and Monte Carlo simulation were compared with those provided by the GZP6 treatment planning system. Results Scanning of samples of uniformly irradiated films demonstrated approximately 2.85% and 4.97% nonuniformity of the response, respectively in the longitudinal and transverse directions of the film. Our findings have also indicated that the film response is not affected by the exposure to the scanner’s light source, particularly in multiple scanning of film. The results of radiochromic film measurements are in good agreement with the Monte Carlo calculations (4%) and the corresponding dose values presented by the GZP6 treatment planning system (5%). Conclusions The results of these investigations indicate that the Microtek ScanMaker 1000XL color scanner in conjunction with GafChromic EBT film is a reliable system for dosimetric evaluation of a high dose rate brachytherapy source. PMID:23411947

Head-to-head comparison of H2-receptor antagonists and proton pump inhibitors in the treatment of erosive esophagitis: A meta-analysis

PubMed Central

Wang, Wei-Hong; Huang, Jia-Qing; Zheng, Ge-Fan; Xia, Harry Hua-Xiang; Wong, Wai-Man; Lam, Shiu-Kum; Wong, Benjamin Chun-Yu

2005-01-01

AIM: To systematically evaluate the efficacy of H2-receptor antagonists (H2RAs) and proton pump inhibitors in healing erosive esophagitis (EE). METHODS: A meta-analysis was performed. A literature search was conducted in PubMed, Medline, Embase, and Cochrane databases to include randomized controlled head-to-head comparative trials evaluating the efficacy of H2RAs or proton pump inhibitors in healing EE. Relative risk (RR) and 95% confidence interval (CI) were calculated under a random-effects model. RESULTS: RRs of cumulative healing rates for each comparison at 8 wk were: high dose vs standard dose H2RAs, 1.17 (95%CI, 1.02-1.33); standard dose proton pump inhibitors vs standard dose H2RAs, 1.59 (95%CI, 1.44-1.75); standard dose other proton pump inhibitors vs standard dose omeprazole, 1.06 (95%CI, 0.98-1.06). Proton pump inhibitors produced consistently greater healing rates than H2RAs of all doses across all grades of esophagitis, including patients refractory to H2RAs. Healing rates achieved with standard dose omeprazole were similar to those with other proton pump inhibitors in all grades of esophagitis. CONCLUSION: H2RAs are less effective for treating patients with erosive esophagitis, especially in those with severe forms of esophagitis. Standard dose proton pump inhibitors are significantly more effective than H2RAs in healing esophagitis of all grades. Proton pump inhibitors given at the recommended dose are equally effective for healing esophagitis. PMID:15996033

SU-E-T-413: Examining Acquisition Rate for Using MatriXX Ion Chamber Array to Measure HDR Brachytherapy Treatments

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

Wagar, M; Bhagwat, M; O’Farrell, D

2015-06-15

Purpose: There are unique obstacles to implementing the MatriXX ionchamber array as a QA tool in Brachytherapy given that the device is designed for use in the MV energy range. One of the challenges we investigate is the affect of acquisition rates on dose measurement accuracy for HDR treatment plans. Methods: A treatment plan was optimized in Oncentra Brachy TPS to deliver a planar dose to a 5×5cm region at 10mm depth. The applicator was affixed to the surface of the MatriXX array. The plan was delivered multiple times using a Nucleatron HDR afterloader with a 2.9Ci Ir192 source. Formore » each measurement the sampling rate of the MatriXX movie mode was varied (30ms and 500ms). This experiment was repeated with identical parameters, following a source exchange, with an 11.2Ci Ir192 source. Finally, a single snap measurement was acquired. Analysis was preformed to evaluate the fidelity of the dose delivery for each iteration of the experiment. Evaluation was based on the comparison between the measured and TPS predicted dose. Results: Higher sample rates induce a greater discrepancy between the predicted and measured dose. Delivering the plan using a lower activity source also produced greater discrepancy in the measurement due to the increased delivery time. Analyzing the single snap measurement showed little difference from the 500ms integral dose measurement. Conclusion: The advantage of using movie mode for HDR treatment delivery QA is the ability for real time source tracking in addition to dose measurement. Our analysis indicates that 500ms is an optimal frame rate.« less

SU-E-T-159: Characteristics of Fiber-Optic Radiation Sensor for Proton Therapeutic Beam

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

Son, J; Kim, M; Hwang, U

Purpose: A fiber-optic radiation sensor using Cerenkov radiation has been widely studied for use as a dosimeter for proton therapeutic beam. Although the fiber-optic radiation sensor has already been investigated for proton therapeutic, it has been examined relatively little work for clinical therapeutic proton beams. In this study, we evaluated characteristics of a fiber-optic radiation sensor for clinical therapeutic proton beams. We experimentally evaluated dose-rate dependence, dose response and energy dependence for the proton beam. Methods: A fiber-optic radiation sensor was placed in a water phantom. Beams with energies of low, middle and high were used in the passively-scattered protonmore » therapeutic beam at the National Cancer Center in Korea. The sensor consists of two plastic optical fibers (POF). A reference POF and 2 cm longer POF were used to utilize the subtraction method for having sensitive volume. Each POF is optically coupled to the Multi-Anode Photo Multiplier Tube (MAPMT) and the MAPMT signals are processed using National Instruments Data Acquisition System (NI-DAQ). We were investigated dosimetric properties including dose-rate dependence, dose response and energy dependence. Results: We have successfully evaluated characteristics of a fiber optic radiation sensor using Cerenkov radiation. The fiber-optic radiation sensor showed the dose response linearity and low energy dependence. In addition, as the dose-rate was increased, Cerenkov radiation increased linearly. Conclusion: We evaluated the basic characteristics of the fiber optic radiation sensor, the dosimetry tool, to raise the quality of proton therapy. Based on the research, we developed a real time dosimetry system of the optic fiber to confirm the real time beam position and energy for therapeutic proton pencil beam.« less

Evaluation of characteristics of high-energy electron beams using N-isopropyl-acrylamide gel dosimeter

NASA Astrophysics Data System (ADS)

Shih, Tian-Yu; Yen, Tsung-Hsien; Liu, Yan-Lin; Luzhbin, Dmytro; Wu, Jay

2017-11-01

The advantage of electron beam radiotherapy is that the absorbed dose rapidly decreases with the increasing depth, which can prevent damage to deeper organs and tissues. Accurately evaluating the absorbed dose in the superficial tumor is imperative. This study assessed the characteristics of electron beams by using the N-isopropyl-acrylamide (n-NIPAM) gel dosimeter. The n-NIPAM gel was composed of 6% gelatin, 5% monomer, and 2.5% cross-linker with 5 mM tetrakis (hydroxymethyl) phosphonium chloride for deoxygenation. The gel was irradiated with 6-, 9-, and 12-MeV electron beams with dose rates of 100-600 MU/min, respectively. The energy dependence and dose rate dependence were assessed. The beam profiles and percentage depth doses were measured and compared with the results of the Gafchromic film and ionization chamber. The linearity of the n-NIPAM gel under 6-, 9-, and 12-MeV electrons was larger than 0.990 with 2% variation in sensitivity. The sensitivity of the gel under 100-600 MU/min showed 5% variations. The energy and dose rate dependence can be negligible. The beam profiles and percentage depth doses measured by the n-NIPAM gel matched well with the results of the ionization chamber and film. This study reveals the possibility of using the n-NIPAM gel dosimeter for electron beam measurements in clinical radiotherapy.

Efficacy and Safety of OnabotulinumtoxinA Treatment of Forehead Lines: A Multicenter, Randomized, Dose-Ranging Controlled Trial.

PubMed

Solish, Nowell; Rivers, Jason K; Humphrey, Shannon; Muhn, Channy; Somogyi, Chris; Lei, Xiaofang; Bhogal, Meetu; Caulkins, Carrie

2016-03-01

Various onabotulinumtoxinA doses are effective in treating forehead lines (FHL), with a trend toward lower doses. To evaluate efficacy and safety of onabotulinumtoxinA dose-ranging treatment of FHL when the frontalis area and glabellar complex are treated together. Adults with moderate-to-severe FHL received onabotulinumtoxinA 40 U (FHL, 20 U; glabellar lines [GL], 20 U), 30 U (FHL, 10 U; GL, 20 U), or placebo. Response was assessed at weeks 1, 2, day 30, and monthly to day 180. Coprimary efficacy end points were investigator- and subject-assessed Facial Wrinkle Scale scores of none or mild (day 30). Patient-reported outcomes, onset/duration of effect, and adverse events (AEs) were evaluated. Responder rates (investigator/subject, respectively) were 40-U group, 91.2%/89.5%; 30-U group, 86.4%/81.4%; placebo, 1.7%/5.1%. OnabotulinumtoxinA resulted in significantly greater responder rates than placebo (p < .001). Adverse events were mild to moderate and similar between groups (most common AEs: nasopharyngitis [4.6%] and headache [4.0%]). Treatment of FHL with onabotulinumtoxinA 40 and 30 U (in frontalis and glabellar complex muscles) was tolerable, effective, and sustained. Both doses significantly reduced FHL severity; however, the 40-U dose demonstrated a trend toward greater sustained benefit and longer duration of effect versus the 30-U dose, with similar AE rates.

Evaluation of the Pharmacokinetics and Efficacy of a Busulfan Test Dose in Adult Patients Undergoing Myeloablative Hematopoietic Cell Transplantation.

PubMed

Weil, Elizabeth; Zook, Felicia; Oxencis, Carolyn; Canadeo, Angela; Urmanski, Angela; Waggoner, Mindy; Eastwood, Daniel; Pasquini, Marcelo; Hamadani, Mehdi; Hari, Parameswaran

2017-06-01

Owing to interpatient variability in busulfan exposure, therapeutic monitoring of busulfan is often used in myeloablative allogeneic transplantation to ensure that patients are near the optimal steady-state goal of 900 ng/mL. One challenge in therapeutic monitoring of busulfan is the brief course of busulfan treatment, requiring prompt analysis and dose adjustments as needed. Pharmacokinetic evaluation of a busulfan test dose before the start of the conditioning regimen would allow for all conditioning regimen doses to be given at the calculated optimized dose. An observational study was completed to evaluate the effects of a busulfan test dose of 0.9 mg/kg administered before the start of a myeloablative intravenous busulfan-based conditioning regimen. Sixty adult patients who received a busulfan conditioning regimen were reviewed, including 30 patients prior to the implementation of the busulfan test dose (pretest dose group) and 30 patients who received the busulfan test dose (posttest dose group). The primary objective was a pharmacokinetic evaluation of the percentage of patients who achieved the desired steady-state goal using the test dose strategy. The safety and efficacy of the busulfan test dose were evaluated as well. The average busulfan steady-state level after the first dose of the conditioning regimen was significantly lower in the pre-test dose group compared with the post-test dose group (660 ng/mL versus 879.9 ng/mL; P < 0.001). Compared with the post-test dose group, significantly fewer patients in the pre-test dose group were within 10% of the busulfan steady-state goal (10% versus 73.3%; P < 0.001) or within 5% of the goal (0% versus 53%; P < 0.001). Requirements for parenteral nutrition and/or patient-controlled analgesia owing to mucositis and rates of veno-occlusive disease were not significantly different between the pre-test dose group and the post-test dose group. The rates of disease relapse, mortality, and acute graft-versus-host disease were similar in the two groups. A pretransplantation busulfan test dose of 0.9 mg/kg improved the patients' ability to reach therapeutic busulfan target levels after the first conditioning dose and resulted in fewer adjustments during conditioning. The use of a busulfan test dose did not significantly increase patients' risk of mucositis or other safety outcomes. Copyright © 2017 The American Society for Blood and Marrow Transplantation. Published by Elsevier Inc. All rights reserved.

Modelling evolution of air dose rates in river basins in Fukushima Prefecture affected by sediment-sorbed radiocesium redistribution

NASA Astrophysics Data System (ADS)

Malins, A.; Sakuma, K.; Nakanishi, T.; Kurikami, H.; Machida, M.; Kitamura, A.; Yamada, S.

2015-12-01

The radioactive 134Cs and 137Cs isotopes deposited over Fukushima Prefecture by the Fukushima Daiichi nuclear disaster are the predominant radiological concern for the years following the accident. This is because the energetic gamma radiation they emit on decay constitutes the majority of the elevated air dose rates that now afflict the region. Therefore, we developed a tool for calculating air dose rates from arbitrary radiocesium spatial distributions across the land surface and depth profiles within the ground. As cesium is strongly absorbed by clay soils, its primary redistribution mechanism within Fukushima Prefecture is by soil erosion and water-borne sediment transport. Each year between 0.1~1% of the total radiocesium inventory in the river basins neighboring Fukushima Daiichi is eroded from the land surface and enters into water courses, predominantly during typhoon storms. Although this is a small amount in relative terms, in absolute terms it corresponds to terabecquerels of 134Cs and 137Cs redistribution each year and this can affect the air dose rate at locations of high erosion and sediment deposition. This study inputs the results of sediment redistribution simulations into the dose rate evaluation tool to calculate the locations and magnitude of air dose rate changes due to radiocesium redistribution. The dose rate calculations are supported by handheld survey instrument results taken within the Prefecture.

Treatment efficacy and safety of low-dose azathioprine in chronic active ulcerative colitis patients: A meta-analysis and systemic review.

PubMed

Luan, Zi Jian; Li, Yue; Zhao, Xin Yu; Wang, Li; Sun, Ying Hao; Wang, Shi Yao; Qian, Jia Ming

2016-10-01

To evaluate the efficacy and safety of low-dose azathioprine (AZA) in treating patients with chronic active ulcerative colitis (UC). A literature search of Medline, Embase, the Cochrane Library, Web of Science, Wanfang Database, CNKI, SinoMed, VIP Chinese Science and the Technology Journals Database was conducted to identify eligible studies that evaluated the efficacy and safety of low-dose azathioprine (AZA) in treating patients with chronic active UC published up to 15 July 2015. Data were extracted from the studies, including clinical efficacy (response rate, adverse drug reaction [ADR] rate, steroid withdrawal rate and relapse rate) and endoscopic improvement (endoscopic remission rate and mucosal healing rate). Six studies with 211 patients were eligible for the analysis. The overall response rates after 6 and 12 months of treatment were 78.0% (95% confidence interval [CI] 71.0-85.0%) and 88.0% (95% CI 80.0-96.0%), respectively. The overall ADR rate was 25.0% (95% CI 18.0-31.0%). Endoscopic response rate was around 85.0%, while the endoscopic remission rates and mucosal healing rates after 6 and 12 months of treatment were above 60.0% and 70.0%, respectively. The steroid withdrawal rate and relapse rate were in moderate to high heterogeneity. Egger's test indicated that there was no publication bias for studies regarding the 6-month response rate and ADR rate. Low-dose AZA is effective and safe in the treatment of chronic active UC patients. However, randomized controlled trials with large sample sizes are needed to draw definitive conclusions. © 2016 Chinese Medical Association Shanghai Branch, Chinese Society of Gastroenterology, Renji Hospital Affiliated to Shanghai Jiaotong University School of Medicine and John Wiley & Sons Australia, Ltd.

Continuous Exposure to Low-Dose-Rate Gamma Irradiation Reduces Airway Inflammation in Ovalbumin-Induced Asthma.

PubMed

Kim, Joong Sun; Son, Yeonghoon; Bae, Min Ji; Lee, Seung Sook; Park, Sun Hoo; Lee, Hae June; Lee, Soong In; Lee, Chang Geun; Kim, Sung Dae; Jo, Wol Soon; Kim, Sung Ho; Shin, In Sik

2015-01-01

Although safe doses of radiation have been determined, concerns about the harmful effects of low-dose radiation persist. In particular, to date, few studies have investigated the correlation between low-dose radiation and disease development. Asthma is a common chronic inflammatory airway disease that is recognized as a major public health problem. In this study, we evaluated the effects of low-dose-rate chronic irradiation on allergic asthma in a murine model. Mice were sensitized and airway-challenged with ovalbumin (OVA) and were exposed to continuous low-dose-rate irradiation (0.554 or 1.818 mGy/h) for 24 days after initial sensitization. The effects of chronic radiation on proinflammatory cytokines and the activity of matrix metalloproteinase-9 (MMP-9) were investigated. Exposure to low-dose-rate chronic irradiation significantly decreased the number of inflammatory cells, methylcholine responsiveness (PenH value), and the levels of OVA-specific immunoglobulin E, interleukin (IL)-4, and IL-5. Furthermore, airway inflammation and the mucus production in lung tissue were attenuated and elevated MMP-9 expression and activity induced by OVA challenge were significantly suppressed. These results indicate that low-dose-rate chronic irradiation suppresses allergic asthma induced by OVA challenge and does not exert any adverse effects on asthma development. Our findings can potentially provide toxicological guidance for the safe use of radiation and relieve the general anxiety about exposure to low-dose radiation.

Evaluation of the stepwise collimation method for the reduction of the patient dose in full spine radiography

NASA Astrophysics Data System (ADS)

Lee, Boram; Lee, Sunyoung; Yang, Injeong; Yoon, Myeonggeun

2014-05-01

The purpose of this study is to evaluate the dose reduction when using the stepwise collimation method for scoliosis patients undergoing full spine radiography. A Monte Carlo simulation was carried out to acquire dose vs. volume data for organs at risk (OAR) in the human body. While the effective doses in full spine radiography were reduced by 8, 15, 27 and 44% by using four different sizes of the collimation, the doses to the skin were reduced by 31, 44, 55 and 66%, indicating that the reduction of the dose to the skin is higher than that to organs inside the body. Although the reduction rates were low for the gonad, being 9, 14, 18 and 23%, there was more than a 30% reduction in the dose to the heart, suggesting that the dose reduction depends significantly on the location of the OARs in the human body. The reduction rate of the secondary cancer risk based on the excess absolute risk (EAR) varied from 0.6 to 3.4 per 10,000 persons, depending on the size of the collimation. Our results suggest that the stepwise collimation method in full spine radiography can effectively reduce the patient dose and the radiation-induced secondary cancer risk.

Application of the Monte Carlo method to the analysis of doses and shielding around an X-ray fluorescence equipment

NASA Astrophysics Data System (ADS)

Ródenas, José; Juste, Belén; Gallardo, Sergio; Querol, Andrea

2017-09-01

An X-ray fluorescence equipment is used for practical exercises in the laboratory of Nuclear Engineering of the Polytechnic University of Valencia (Spain). This equipment includes a compact X-ray tube, ECLIPSE-III, and a Si-PIN XR-100T detector. The voltage (30 kV), and the current (100 μA) of the tube are low enough so that expected doses around the tube do not represent a risk for students working in the laboratory. Nevertheless, doses and shielding should be evaluated to accomplish the ALARA criterion. The Monte Carlo method has been applied to evaluate the dose rate around the installation provided with a shielding composed by a box of methacrylate. Dose rates calculated are compared with experimental measurements to validate the model. Obtained results show that doses are below allowable limits. Hence, no extra shielding is required for the X-ray beam. A previous Monte Carlo model was also developed to obtain the tube spectrum and validated by comparison with data from manufacturer.

A randomized, double-blind, controlled clinical trial to evaluate the efficacy and safety of CJ-50300, a newly developed cell culture-derived smallpox vaccine, in healthy volunteers.

PubMed

Jang, Hee-Chang; Kim, Choong Jong; Kim, Kye Hyoung; Lee, Kwang-Hee; Byun, Young-Ho; Seong, Baik-Lin; Saletti, Giulietta; Czerkinsky, Cecil; Park, Wan Beom; Park, Sang-Won; Kim, Hong-Bin; Kim, Nam Joong; Oh, Myoung-don

2010-08-16

A randomized, double-blind, controlled clinical trial was conducted to evaluate the efficacy and safety of CJ-50300, a newly developed cell culture-derived smallpox vaccine, and to determine its minimum effective dose. The overall rates of cutaneous "take" reaction and humoral and cellular immunogenicity in CJ-50300 vaccinees were 100% (123/123), 99.2% (122/123), and 90.8% (109/120), respectively, and these rates did not differ significantly between the conventional-dose and the low-dose CJ-50300 (1.0x10(8) and 1.0x10(7) plaque-forming units/mL, respectively) (P>0.05 for each). No serious adverse reaction was observed. However, one case of possible generalized vaccinia occurred in the conventionally dosed group [ClinicalTrials.gov Identifier: NCT00607243].

Comparative analysis of dose rates in bricks determined by neutron activation analysis, alpha counting and X-ray fluorescence analysis for the thermoluminescence fine grain dating method

NASA Astrophysics Data System (ADS)

Bártová, H.; Kučera, J.; Musílek, L.; Trojek, T.

2014-11-01

In order to evaluate the age from the equivalent dose and to obtain an optimized and efficient procedure for thermoluminescence (TL) dating, it is necessary to obtain the values of both the internal and the external dose rates from dated samples and from their environment. The measurements described and compared in this paper refer to bricks from historic buildings and a fine-grain dating method. The external doses are therefore negligible, if the samples are taken from a sufficient depth in the wall. However, both the alpha dose rate and the beta and gamma dose rates must be taken into account in the internal dose. The internal dose rate to fine-grain samples is caused by the concentrations of natural radionuclides 238U, 235U, 232Th and members of their decay chains, and by 40K concentrations. Various methods can be used for determining trace concentrations of these natural radionuclides and their contributions to the dose rate. The dose rate fraction from 238U and 232Th can be calculated, e.g., from the alpha count rate, or from the concentrations of 238U and 232Th, measured by neutron activation analysis (NAA). The dose rate fraction from 40K can be calculated from the concentration of potassium measured, e.g., by X-ray fluorescence analysis (XRF) or by NAA. Alpha counting and XRF are relatively simple and are accessible for an ordinary laboratory. NAA can be considered as a more accurate method, but it is more demanding regarding time and costs, since it needs a nuclear reactor as a neutron source. A comparison of these methods allows us to decide whether the time- and cost-saving simpler techniques introduce uncertainty that is still acceptable.

Optical-CT 3D Dosimetry Using Fresnel Lenses with Minimal Refractive-Index Matching Fluid

PubMed Central

Bache, Steven; Malcolm, Javian; Adamovics, John; Oldham, Mark

2016-01-01

Telecentric optical computed tomography (optical-CT) is a state-of-the-art method for visualizing and quantifying 3-dimensional dose distributions in radiochromic dosimeters. In this work a prototype telecentric system (DFOS—Duke Fresnel Optical-CT Scanner) is evaluated which incorporates two substantial design changes: the use of Fresnel lenses (reducing lens costs from $10-30K t0 $1-3K) and the use of a ‘solid tank’ (which reduces noise, and the volume of refractively matched fluid from 1ltr to 10cc). The efficacy of DFOS was evaluated by direct comparison against commissioned scanners in our lab. Measured dose distributions from all systems were compared against the predicted dose distributions from a commissioned treatment planning system (TPS). Three treatment plans were investigated including a simple four-field box treatment, a multiple small field delivery, and a complex IMRT treatment. Dosimeters were imaged within 2h post irradiation, using consistent scanning techniques (360 projections acquired at 1 degree intervals, reconstruction at 2mm). DFOS efficacy was evaluated through inspection of dose line-profiles, and 2D and 3D dose and gamma maps. DFOS/TPS gamma pass rates with 3%/3mm dose difference/distance-to-agreement criteria ranged from 89.3% to 92.2%, compared to from 95.6% to 99.0% obtained with the commissioned system. The 3D gamma pass rate between the commissioned system and DFOS was 98.2%. The typical noise rates in DFOS reconstructions were up to 3%, compared to under 2% for the commissioned system. In conclusion, while the introduction of a solid tank proved advantageous with regards to cost and convenience, further work is required to improve the image quality and dose reconstruction accuracy of the new DFOS optical-CT system. PMID:27019460

Optical-CT 3D Dosimetry Using Fresnel Lenses with Minimal Refractive-Index Matching Fluid.

PubMed

Bache, Steven; Malcolm, Javian; Adamovics, John; Oldham, Mark

2016-01-01

Telecentric optical computed tomography (optical-CT) is a state-of-the-art method for visualizing and quantifying 3-dimensional dose distributions in radiochromic dosimeters. In this work a prototype telecentric system (DFOS-Duke Fresnel Optical-CT Scanner) is evaluated which incorporates two substantial design changes: the use of Fresnel lenses (reducing lens costs from $10-30K t0 $1-3K) and the use of a 'solid tank' (which reduces noise, and the volume of refractively matched fluid from 1 ltr to 10 cc). The efficacy of DFOS was evaluated by direct comparison against commissioned scanners in our lab. Measured dose distributions from all systems were compared against the predicted dose distributions from a commissioned treatment planning system (TPS). Three treatment plans were investigated including a simple four-field box treatment, a multiple small field delivery, and a complex IMRT treatment. Dosimeters were imaged within 2 h post irradiation, using consistent scanning techniques (360 projections acquired at 1 degree intervals, reconstruction at 2mm). DFOS efficacy was evaluated through inspection of dose line-profiles, and 2D and 3D dose and gamma maps. DFOS/TPS gamma pass rates with 3%/3mm dose difference/distance-to-agreement criteria ranged from 89.3% to 92.2%, compared to from 95.6% to 99.0% obtained with the commissioned system. The 3D gamma pass rate between the commissioned system and DFOS was 98.2%. The typical noise rates in DFOS reconstructions were up to 3%, compared to under 2% for the commissioned system. In conclusion, while the introduction of a solid tank proved advantageous with regards to cost and convenience, further work is required to improve the image quality and dose reconstruction accuracy of the new DFOS optical-CT system.

Effects of enoxaparin and unfractionated heparin in prophylactic and therapeutic doses on the fertility of female Wistar rats.

PubMed

Figueiró-Filho, Ernesto Antonio; Aydos, Ricardo Dutra; Senefonte, Flávio Renato de Almeida; Ferreira, Cristiane Munaretto; Pereira, Erica Freire de Vasconcelos; Oliveira, Vanessa Marcon de; Menezes, Giovanna Pádoa de; Bósio, Marco Antonio Costa

2014-07-01

To evaluate the effects of exposure of enoxaparin and unfractionated heparin (UFH) in prophylactic and therapeutic doses on the fertility rates of pregnant healthy Wistar rats. Enoxaparin and UFH were administered in prophylactic doses 1 mg/Kg/day 72 UI/Kg/day, and in therapeutic doses at 2 mg/kg/day 400UI/Kg/day. The rats were divided into five groups. The number of live and dead foetuses was quantified. The uterine horns were dissected and the presence of early and late reabsorptions (abortions) was determined. A p<0.05 was considered statistically significant. We did not observe statistically significant differences between groups when comparing the average weight of the foetuses and placentas, rate of female VS males, rates of pre-implantation loss (RPL), rates of efficiency implantation (REI), rates of post-implantation loss (RPIL) and rates of foetal viability (RFV). There was no significant effect on fertility with the use of anticoagulant drugs in pregnant healthy Wistar rats.

Real-time dosimetry in radiotherapy using tailored optical fibers

NASA Astrophysics Data System (ADS)

Rahman, A. K. M. Mizanur; Zubair, H. T.; Begum, Mahfuza; Abdul-Rashid, H. A.; Yusoff, Z.; Omar, Nasr Y. M.; Ung, N. M.; Mat-Sharif, K. A.; Bradley, D. A.

2016-05-01

Real-time dosimetry plays an important role for accurate patient-dose measurement during radiotherapy. A tiny piece of laboratory fabricated Ge-doped optical fiber has been investigated as a radioluminescence (RL) sensor for real-time dosimetry over the dose range from 1 Gy to 8 Gy under 6 MV photon beam by LINAC. Fiber-coupled software-based RL prototype system was used to assess essential dosimetric characteristics including dose response linearity, dose rate dependency, sensitivity, repeatability and output dependence on field sizes. The consistency level of RL photon counts versus dose rate was also compared with that of standard Al2O3:C chips. Sensitivity of Ge-doped fiber were found to be sufficiently sensitive for practical use and also provided linear dose responses for various dose rates from 100 cGy/min to 600 cGy/min using both 6 MV photon and 6 MeV electron beams. SEM-EDX analysis was performed to identify Ge-dopant concentration level within the optical fiber RL material. Accumulated doses were also estimated using simple integral technique and the error was found to be around less than 1% under dissimilar dose rates or repeat measurements. The evaluation of the Ge-doped optical fiber based RL dosimeter system indicates its potential in medical dosimetry.

Can we avoid dose escalation for intermediate-risk prostate cancer in the setting of short-course neoadjuvant androgen deprivation?

PubMed

Shakespeare, Thomas P; Wilcox, Shea W; Aherne, Noel J

2016-01-01

Both dose-escalated external beam radiotherapy (DE-EBRT) and androgen deprivation therapy (ADT) improve the outcomes in patients with intermediate-risk prostate cancer. Despite this, there are only few reports evaluating DE-EBRT for patients with intermediate-risk prostate cancer receiving neoadjuvant ADT, and virtually no studies investigating dose escalation >74 Gy in this setting. We aimed to determine whether DE-EBRT >74 Gy improved the outcomes for patients with intermediate-risk prostate cancer who received neoadjuvant ADT. In our institution, patients with intermediate-risk prostate cancer were treated with neoadjuvant ADT and DE-EBRT, with doses sequentially increasing from 74 Gy to 76 Gy and then to 78 Gy between 2006 and 2012. We identified 435 patients treated with DE-EBRT and ADT, with a median follow-up of 70 months. For the 74 Gy, 76 Gy, and 78 Gy groups, five-year biochemical disease-free survival rates were 95.0%, 97.8%, and 95.3%, respectively; metastasis-free survival rates were 99.1%, 100.0%, and 98.6%, respectively; and prostate cancer-specific survival rate was 100% for all three dose levels. There was no significant benefit for dose escalation either on univariate or multivariate analysis for any outcome. There was no benefit for DE-EBRT >74 Gy in our cohort of intermediate-risk prostate cancer patients treated with neoadjuvant ADT. Given the higher risks of toxicity associated with dose escalation, it may be feasible to omit dose escalation in this group of patients. Randomized studies evaluating dose de-escalation should be considered.

Can we avoid dose escalation for intermediate-risk prostate cancer in the setting of short-course neoadjuvant androgen deprivation?

PubMed Central

Shakespeare, Thomas P; Wilcox, Shea W; Aherne, Noel J

2016-01-01

Background Both dose-escalated external beam radiotherapy (DE-EBRT) and androgen deprivation therapy (ADT) improve the outcomes in patients with intermediate-risk prostate cancer. Despite this, there are only few reports evaluating DE-EBRT for patients with intermediate-risk prostate cancer receiving neoadjuvant ADT, and virtually no studies investigating dose escalation >74 Gy in this setting. We aimed to determine whether DE-EBRT >74 Gy improved the outcomes for patients with intermediate-risk prostate cancer who received neoadjuvant ADT. Findings In our institution, patients with intermediate-risk prostate cancer were treated with neoadjuvant ADT and DE-EBRT, with doses sequentially increasing from 74 Gy to 76 Gy and then to 78 Gy between 2006 and 2012. We identified 435 patients treated with DE-EBRT and ADT, with a median follow-up of 70 months. For the 74 Gy, 76 Gy, and 78 Gy groups, five-year biochemical disease-free survival rates were 95.0%, 97.8%, and 95.3%, respectively; metastasis-free survival rates were 99.1%, 100.0%, and 98.6%, respectively; and prostate cancer-specific survival rate was 100% for all three dose levels. There was no significant benefit for dose escalation either on univariate or multivariate analysis for any outcome. Conclusion There was no benefit for DE-EBRT >74 Gy in our cohort of intermediate-risk prostate cancer patients treated with neoadjuvant ADT. Given the higher risks of toxicity associated with dose escalation, it may be feasible to omit dose escalation in this group of patients. Randomized studies evaluating dose de-escalation should be considered. PMID:27073327

RESPONSE OF THE GREEK EARLY WARNING SYSTEM REUTER-STOKES IONIZATION CHAMBERS TO TERRESTRIAL AND COSMIC RADIATION EVALUATED IN COMPARISON WITH SPECTROSCOPIC DATA AND TIME SERIES ANALYSIS.

PubMed

Leontaris, F; Clouvas, A; Xanthos, S; Maltezos, A; Potiriadis, C; Kiriakopoulos, E; Guilhot, J

2018-02-01

The Telemetric Early Warning System Network of the Greek Atomic Energy Commission consists mainly of a network of 24 Reuter-Stokes high-pressure ionization chambers (HPIC) for gamma dose rate measurements and covers all Greece. In the present work, the response of the Reuter-Stokes HPIC to terrestrial and cosmic radiation was evaluated in comparison with spectroscopic data obtained by in situ gamma spectrometry measurements with portable hyper pure Germanium detectors (HPGe), near the Reuter-Stokes detectors and time series analysis. For the HPIC detectors, a conversion factor for the measured absorbed dose rate in air (in nGy h-1) to the total ambient dose equivalent rate Ḣ*(10), due to terrestrial and cosmic component, was deduced by the field measurements. Time series analysis of the mean monthly dose rate (measured by the Reuter-Stokes detector in Thessaloniki, northern Greece, from 2001 to 2016) was performed with advanced statistical methods (Fast Fourier Analysis and Zhao Atlas Marks Transform). Fourier analysis reveals several periodicities (periodogram). The periodogram of the absorbed dose rate in air values was compared with the periodogram of the values measured for the same period (2001-16) and in the same location with a NaI (Tl) detector which in principle is not sensitive to cosmic radiation. The obtained results are presented and discussed. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Cocaine self-administration under variable-dose schedules in squirrel monkeys.

PubMed

Panlilio, Leigh V; Thorndike, Eric B; Schindler, Charles W

2006-06-01

Squirrel monkeys self-administered cocaine under a variable-dose schedule, with the dose varied from injection to injection. As in earlier studies with rats, post-injection pauses varied as a monotonic function of dose, allowing a cocaine dose-effect curve to be obtained during each session. These curves were shifted by pretreatment with dopamine antagonists, demonstrating that this procedure may provide an efficient means of evaluating treatments that affect drug self-administration. However, drug intake eventually became "dysregulated" after extensive training (100-300 sessions), with relatively short pauses following all doses. Dose-sensitivity was restored by adding a 60-s timeout period after each injection, suggesting that dysregulation occurred because the monkeys developed a tendency to self-administer another injection before the previous injection had been adequately distributed. Finally, when the response requirement under the variable-dose schedule was increased from 1 to 10, both the post-injection pause and the rate of responding following the pause ("run rates") were found to vary with dose. The dose-dependency of run rates suggests that post-injection pauses reflect not only motivational factors, such as satiety, but also the direct effects of cocaine on leverpressing.

Use of radiation protraction to escalate biologically effective dose to the treatment target

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

Kuperman, V. Y.; Spradlin, G. S.; Department of Mathematics, Embry-Riddle University, Daytona Beach, Florida 32114

2011-12-15

Purpose: The aim of this study is to evaluate how simultaneously increasing fraction time and dose per fraction affect biologically effective dose for the target (BED{sub tar}) while biologically effective dose for the normal tissue (BED{sub nt}) is fixed. Methods: In this investigation, BED{sub tar} and BED{sub nt} were studied by assuming mono-exponential repair of sublethal damage with tissue dependent repair half-time. Results: Our results demonstrate that under certain conditions simultaneously increasing fraction time and dose per fraction result in increased BED{sub tar} while BED{sub nt} is fixed. The dependence of biologically effective dose on fraction time is influenced bymore » the dose rate. In this investigation we analytically determined time-varying dose rate R-tilde which minimizes BED. Changes in BED with fraction time were compared for constant dose rate and for R-tilde. Conclusions: A number of recent experimental and theoretical studies have demonstrated that slow delivery of radiation (known as radiation protraction) leads to reduced therapeutic effect because of increased repair of sublethal damage. In contrast, our analysis shows that under certain conditions simultaneously increasing fraction time and dose per fraction are radiobiologically advantageous.« less

Results of nDOSE and HiDOSE Experiments for Dosimetric Evaluation During STS-134 Mission

NASA Astrophysics Data System (ADS)

Pugliese, M.; Loffredo, F.; Quarto, M.; Roca, V.; Mattone, C.; Borla, O.; Zanini, A.

2014-07-01

HiDOSE (Heavy ion DOSimetry Experiment) and nDOSE (neutron DOSimetry Experiment) experiments conducted as a part of BIOKIS (Biokon in Space) payload were designed to measure the dose equivalent due to charged particles and to neutron field, on the entire energy range, during STS-134 mission. Given the complexity of the radiation field in space environment, dose measurements should be considered an asset of any space mission, and for this reason HiDOSE and nDOSE experiments represent an important contribution to the radiation environment assessment during this mission, a short duration flight. The results of these experiments, obtained using Thermo Luminescence Dosimeters (TLDs) to evaluate the charged particles dosimetry and neutron bubbles dosimeters and stack bismuth track dosimeters for neutron dosimetry, indicate that the dose equivalent rate due to space radiation exposure during the STS-134 mission is in accordance with the results obtained from long duration flights.

Comparison of the uncertainties of several European low-dose calibration facilities

NASA Astrophysics Data System (ADS)

Dombrowski, H.; Cornejo Díaz, N. A.; Toni, M. P.; Mihelic, M.; Röttger, A.

2018-04-01

The typical uncertainty of a low-dose rate calibration of a detector, which is calibrated in a dedicated secondary national calibration laboratory, is investigated, including measurements in the photon field of metrology institutes. Calibrations at low ambient dose equivalent rates (at the level of the natural ambient radiation) are needed when environmental radiation monitors are to be characterised. The uncertainties of calibration measurements in conventional irradiation facilities above ground are compared with those obtained in a low-dose rate irradiation facility located deep underground. Four laboratories quantitatively evaluated the uncertainties of their calibration facilities, in particular for calibrations at low dose rates (250 nSv/h and 1 μSv/h). For the first time, typical uncertainties of European calibration facilities are documented in a comparison and the main sources of uncertainty are revealed. All sources of uncertainties are analysed, including the irradiation geometry, scattering, deviations of real spectra from standardised spectra, etc. As a fundamental metrological consequence, no instrument calibrated in such a facility can have a lower total uncertainty in subsequent measurements. For the first time, the need to perform calibrations at very low dose rates (< 100 nSv/h) deep underground is underpinned on the basis of quantitative data.

SU-E-T-400: Evaluation of Shielding and Activation at Two Pencil Beam Scanning Proton Facilities

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

Remmes, N; Mundy, D; Classic, K

2015-06-15

Purpose: To verify acceptably low dose levels around two newly constructed identical pencil beam scanning proton therapy facilities and to evaluate accuracy of pre-construction shielding calculations. Methods: Dose measurements were taken at select points of interest using a WENDI-2 style wide-energy neutron detector. Measurements were compared to pre-construction shielding calculations. Radiation badges with neutron dose measurement capabilities were worn by personnel and also placed at points throughout the facilities. Seven neutron and gamma detectors were permanently installed throughout the facility, continuously logging data. Potential activation hazards have also been investigated. Dose rates near water tanks immediately after prolonged irradiation havemore » been measured. Equipment inside the treatment room and accelerator vault has been surveyed and/or wipe tested. Air filters from air handling units, sticky mats placed outside of the accelerator vault, and water samples from the magnet cooling water loops have also been tested. Results: All radiation badges have been returned with readings below the reporting minimum. Measurements of mats, air filters, cooling water, wipe tests and surveys of equipment that has not been placed in the beam have all come back at background levels. All survey measurements show the analytical shielding calculations to be conservative by at least a factor of 2. No anomalous events have been identified by the building radiation monitoring system. Measurements of dose rates close to scanning water tanks have shown dose rates of approximately 10 mrem/hr with a half-life less than 5 minutes. Measurements around the accelerator show some areas with dose rates slightly higher than 10 mrem/hr. Conclusion: The shielding design is shown to be adequate. Measured dose rates are below those predicted by shielding calculations. Activation hazards are minimal except in certain very well defined areas within the accelerator vault and for objects placed directly in the path of the beam.« less

Increased medication compliance of liver transplant patients switched from a twice-daily to a once-daily tacrolimus-based immunosuppressive regimen.

PubMed

Eberlin, M; Otto, G; Krämer, I

2013-01-01

Compliance with immunosuppressive therapy plays a major role in the long-term success of liver transplantation. Thus, the development of strategies to promote compliance of liver transplant patients and its evaluation over time are of particular interest. The main objective of this study was to compare medication compliance rates among liver transplant patients over time after transplantation where switched from a twice- to once-daily tacrolimus-based regimen. Sixty-five liver transplant patients being administered tacrolimus-based therapy were classified into three subgroups with regard to time posttransplantation. Medication compliance with tacrolimus-based therapy was measured using an electronic medication event monitoring system over a 12-month period: for 6 months tacrolimus was administered twice-daily and for 6 months, once-daily. Dosing, taking, and timing compliance as well as drug holidays were compared intra-individually between twice- and once-daily intake and among the three subgroups. In addition, patient compliance and quality of life were evaluated using questionnaires. A per protocol analysis of electronically obtained data showed 63 patients to be eligible. The resulting dosing, taking, and timing compliance rates of the patients were higher during the once-daily dosing period. No significant differences in compliance rates with tacrolimus therapy were observed among three subgroups independent of the dosing regimen. More patients failed the correct timing of the evening compared to the morning dose. Missing doses occurred particularly during weekends. Compliance variables measured by questionnaires (Morisky score, self-report, Medication Experience Scale for Immunosuppressants (MESI) score) and the Hospital Anxiety and Depression Scale score were similar in the two dosing periods. The short-form health survey (SF-36) score was higher with once-daily intake. The high measured compliance rates did not vary significantly dependent upon the time after transplantation. Nevertheless, compliance rates were greater using once-daily tacrolimus dosing. Copyright © 2013 Elsevier Inc. All rights reserved.

A model for evaluating radiological impacts on organisms other than man for use in post-closure assessments of geological repositories for radioactive wastes.

PubMed

Thorn, M C; Kelly, M; Rees, J H; Sánchez-Friera, P; Calvez, M

2002-09-01

Bioaccumulation and dosimetric models have been developed that allow the computation of dose rates to a wide variety of plants and animals in the context of the deep geological disposal of solid radioactive wastes. These dose rates can be compared with the threshold dose rates at which significant deleterious effects have been observed in field and laboratory observations. This provides a general indication of whether effects on ecosystems could be observable, but does not quantify the level of those effects. To address this latter issue, two indicator organisms were identified and exposure-response relationships were developed for endpoints of potential interest (mortality in conifers and the induction of skeletal malformations in rodents irradiated in utero). The bioaccumulation, dosimetry and exposure-response models were implemented and used to evaluate the potential significance of radionuclide releases from a proposed deep geological repository for radioactive wastes in France. This evaluation was undertaken in the context of a programme of assessment studies being performed by the Agence nationale pour la gestion des déchets radioactifs (ANDRA).

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.

Long-Segment Fusion for Adult Spinal Deformity Correction Using Low-Dose Recombinant Human Bone Morphogenetic Protein-2: A Retrospective Review of Fusion Rates.

PubMed

Schmitt, Paul J; Kelleher, John P; Ailon, Tamir; Heller, Joshua E; Kasliwal, Manish K; Shaffrey, Christopher I; Smith, Justin S

2016-08-01

Although use of very high-dose recombinant human bone morphogenetic protein-2 (rhBMP-2) has been reported to markedly improve fusion rates in adult spinal deformity (ASD) surgery, most centers use much lower doses due to cost constraints. How effective these lower doses are for fusion enhancement remains unclear. To assess fusion rates using relatively low-dose rhBMP-2 for ASD surgery. This was a retrospective review of consecutive ASD patients that underwent thoracic to sacral fusion. Patients that achieved 2-year follow-up were analyzed. Impact of patient and surgical factors on fusion rate was assessed, and fusion rates were compared with historical cohorts. Of 219 patients, 172 (78.5%) achieved 2-year follow-up and were analyzed. Using an average rhBMP-2 dose of 3.1 mg/level (average total dose = 35.9 mg/case), the 2-year fusion rate was 73.8%. Cancellous allograft, local autograft, and very limited iliac crest bone graft (<20 mL, obtained during iliac bolt placement) were also used. On multivariate analysis, female sex was associated with a higher fusion rate, whereas age, comorbidity score, deformity type, and 3-column osteotomy were not. There were no complications directly attributable to rhBMP-2. Fusion rates for ASD using low-dose rhBMP-2 were comparable to those reported for iliac crest bone graft but lower than for high-dose rhBMP-2. Importantly, there were substantial differences between patients in the present series and those in the historical comparison groups that could not be fully adjusted for based on available data. Prospective evaluation of rhBMP-2 dosing for ASD surgery is warranted to define the most appropriate dose that balances benefits, risks, and costs. ASD, adult spinal deformityICBG, iliac crest bone graftOR, odds ratiorhBMP-2, recombinant human bone morphogenetic protein-2RR, risk ratioTCO, 3-column osteotomy.

Effects of Solar Particle Event Proton Radiation on Parameters Related to Ferret Emesis

PubMed Central

Sanzari, J. K.; Wan, X. S.; Krigsfeld, G. S.; King, G. L.; Miller, A.; Mick, R.; Gridley, D. S.; Wroe, A. J.; Rightnar, S.; Dolney, D.; Kennedy, A. R.

2013-01-01

The effectiveness of simulated solar particle event (SPE) proton radiation to induce retching and vomiting was evaluated in the ferret experimental animal model. The endpoints measured in the study included: (1) the fraction of animals that retched or vomited, (2) the number of retches or vomits observed, (3) the latency period before the first retch or vomit and (4) the duration between the first and last retching or vomiting events. The results demonstrated that γ ray and proton irradiation delivered at a high dose rate of 0.5 Gy/min induced dose-dependent changes in the endpoints related to retching and vomiting. The minimum radiation doses required to induce statistically significant changes in retching- and vomiting-related endpoints were 0.75 and 1.0 Gy, respectively, and the relative biological effectiveness (RBE) of proton radiation at the high dose rate did not significantly differ from 1. Similar but less consistent and smaller changes in the retching- and vomiting-related endpoints were observed for groups irradiated with γ rays and protons delivered at a low dose rate of 0.5 Gy/h. Since this low dose rate is similar to a radiation dose rate expected during a SPE, these results suggest that the risk of SPE radiation-induced vomiting is low and may reach statistical significance only when the radiation dose reaches 1 Gy or higher. PMID:23883319

Acute Hematological Effects in Mice Exposed to the Expected Doses, Dose-rates, and Energies of Solar Particle Event-like Proton Radiation.

PubMed

Sanzari, Jenine K; Cengel, Keith A; Wan, X Steven; Rusek, Adam; Kennedy, Ann R

2014-07-01

NASA has funded several projects that have provided evidence for the radiation risk in space. One radiation concern arises from solar particle event (SPE) radiation, which is composed of energetic electrons, protons, alpha particles and heavier particles. SPEs are unpredictable and the accompanying SPE radiation can place astronauts at risk of blood cell death, contributing to a weakened immune system and increased susceptibility to infection. The doses, dose rates, and energies of the proton radiation expected to occur during a SPE have been simulated at the NASA Space Radiation Laboratory, Brookhaven National Laboratory, delivering total body doses to mice. Hematological values were evaluated at acute time points, up to 24 hrs. post-radiation exposure.

Acute hematological effects in mice exposed to the expected doses, dose-rates, and energies of solar particle event-like proton radiation

NASA Astrophysics Data System (ADS)

Sanzari, Jenine K.; Cengel, Keith A.; Steven Wan, X.; Rusek, Adam; Kennedy, Ann R.

2014-07-01

NASA has funded several projects that have provided evidence for the radiation risk in space. One radiation concern arises from solar particle event (SPE) radiation, which is composed of energetic electrons, protons, alpha particles and heavier particles. SPEs are unpredictable and the accompanying SPE radiation can place astronauts at risk of blood cell death, contributing to a weakened immune system and increased susceptibility to infection. The doses, dose rates, and energies of the proton radiation expected to occur during an SPE have been simulated at the NASA Space Radiation Laboratory, Brookhaven National Laboratory, delivering total body doses to mice. Hematological values were evaluated at acute time points, up to 24 hours post-radiation exposure.

Peri-interventional antibiotic prophylaxis only vs continuous low-dose antibiotic treatment in patients with JJ stents: a prospective randomised trial analysing the effect on urinary tract infections and stent-related symptoms.

PubMed

Moltzahn, Felix; Haeni, Katharina; Birkhäuser, Frédéric D; Roth, Beat; Thalmann, George N; Zehnder, Pascal

2013-02-01

To evaluate the antibiotic treatment regime in patients with indwelling JJ stents, the benefits and disadvantages of a peri-interventional antibiotic prophylaxis were compared with those of a continuous low-dose antibiotic treatment in a prospective randomised trial. In all, 95 patients were randomised to either receive peri-interventional antibiotic prophylaxis during stent insertion only (group A, 44 patients) or to additionally receive a continuous low-dose antibiotic treatment until stent removal (group B, 51). Evaluations for urinary tract infections (UTI), stent-related symptoms (SRSs) and drug side-effects were performed before stent insertion and consecutively after 1, 2 and 4 weeks and/or at stent withdrawal. All patients received a peri-interventional antibiotic prophylaxis with 1.2 g amoxicillin/clavulanic acid. Amoxicillin/clavulanic acid (625 mg) once daily was administered for continuous low-dose treatment (group B). Primary endpoints were the overall rates of UTIs and SRSs. Secondary endpoints were the rates and severity of drug side-effects. Neither the overall UTI rates (group A: 9% vs group B: 10%), nor the rates of febrile UTIs (group A: 7% vs group B: 6%) were different between the groups. Similarly, SRS rates did not differ (group A: 98% vs group B: 96%). Antibiotic side-effect symptoms were to be increased in patients treated with low-dose antibiotics. A continuous antibiotic low-dose treatment during the entire JJ stent-indwelling time does not reduce the quantity or severity of UTIs and has no effect on SRSs either compared with a peri-interventional antibiotic prophylaxis only. © 2012 BJU International.

Evaluation of ambient dose equivalent rates influenced by vertical and horizontal distribution of radioactive cesium in soil in Fukushima Prefecture.

PubMed

Malins, Alex; Kurikami, Hiroshi; Nakama, Shigeo; Saito, Tatsuo; Okumura, Masahiko; Machida, Masahiko; Kitamura, Akihiro

2016-01-01

The air dose rate in an environment contaminated with (134)Cs and (137)Cs depends on the amount, depth profile and horizontal distribution of these contaminants within the ground. This paper introduces and verifies a tool that models these variables and calculates ambient dose equivalent rates at 1 m above the ground. Good correlation is found between predicted dose rates and dose rates measured with survey meters in Fukushima Prefecture in areas contaminated with radiocesium from the Fukushima Dai-ichi Nuclear Power Plant accident. This finding is insensitive to the choice for modeling the activity depth distribution in the ground using activity measurements of collected soil layers, or by using exponential and hyperbolic secant fits to the measurement data. Better predictions are obtained by modeling the horizontal distribution of radioactive cesium across an area if multiple soil samples are available, as opposed to assuming a spatially homogeneous contamination distribution. Reductions seen in air dose rates above flat, undisturbed fields in Fukushima Prefecture are consistent with decrement by radioactive decay and downward migration of cesium into soil. Analysis of remediation strategies for farmland soils confirmed that topsoil removal and interchanging a topsoil layer with a subsoil layer result in similar reductions in the air dose rate. These two strategies are more effective than reverse tillage to invert and mix the topsoil. Copyright © 2015 Elsevier Ltd. All rights reserved.

Measuring in vitro biotransformation rates of super hydrophobic chemicals in rat liver s9 fractions using thin-film sorbent-phase dosing.

PubMed

Lee, Yung-Shan; Otton, S Victoria; Campbell, David A; Moore, Margo M; Kennedy, Chris J; Gobas, Frank A P C

2012-01-03

Methods for rapid and cost-effective assessment of the biotransformation potential of very hydrophobic and potentially bioaccumulative chemicals in mammals are urgently needed for the ongoing global evaluation of the environmental behavior of commercial chemicals. We developed and tested a novel solvent-free, thin-film sorbent-phase in vitro dosing system to measure the in vitro biotransformation rates of very hydrophobic chemicals in male Sprague-Dawley rat liver S9 homogenates and compared the rates to those measured by conventional solvent-delivery dosing. The thin-film sorbent-phase dosing system using ethylene vinyl acetate coated vials was developed to eliminate the incomplete dissolution of very hydrophobic substances in largely aqueous liver homogenates, to determine biotransformation rates at low substrate concentrations, to measure the unbound fraction of substrate in solution, and to simplify chemical analysis by avoiding the difficult extraction of test chemicals from complex biological matrices. Biotransformation rates using sorbent-phase dosing were 2-fold greater than those measured using solvent-delivery dosing. Unbound concentrations of very hydrophobic test chemicals were found to decline with increasing S9 and protein concentrations, causing measured biotransformation rates to be independent of S9 or protein concentrations. The results emphasize the importance of specifying both protein content and unbound substrate fraction in the measurement and reporting of in vitro biotransformation rates of very hydrophobic substances, which can be achieved in a thin-film sorbent-phase dosing system.

Lemna minor plants chronically exposed to ionising radiation: RNA-seq analysis indicates a dose rate dependent shift from acclimation to survival strategies.

PubMed

Van Hoeck, Arne; Horemans, Nele; Nauts, Robin; Van Hees, May; Vandenhove, Hildegarde; Blust, Ronny

2017-04-01

Ecotoxicological research provides knowledge on ionising radiation-induced responses in different plant species. However, the sparse data currently available are mainly extracted from acute exposure treatments. To provide a better understanding of environmental exposure scenarios, the response to stress in plants must be followed in more natural relevant chronic conditions. We previously showed morphological and biochemical responses in Lemna minor plants continuously exposed for 7days in a dose-rate dependent manner. In this study responses on molecular (gene expression) and physiological (photosynthetic) level are evaluated in L. minor plants exposed to ionising radiation. To enable this, we examined the gene expression profiles of irradiated L. minor plants by using an RNA-seq approach. The gene expression data reveal indications that L. minor plants exposed at lower dose rates, can tolerate the exposure by triggering acclimation responses. In contrast, at the highest dose rate tested, a high number of genes related to antioxidative defense systems, DNA repair and cell cycle were differentially expressed suggesting that only high dose rates of ionising radiation drive L. minor plants into survival strategies. Notably, the photosynthetic process seems to be unaffected in L. minor plants among the tested dose rates. This study, supported by our earlier work, clearly indicates that plants shift from acclimation responses towards survival responses at increasing dose rates of ionising radiation. Copyright © 2017 Elsevier B.V. All rights reserved.

Biological equivalence between LDR and PDR in cervical cancer: multifactor analysis using the linear-quadratic model.

PubMed

Couto, José Guilherme; Bravo, Isabel; Pirraco, Rui

2011-09-01

The purpose of this work was the biological comparison between Low Dose Rate (LDR) and Pulsed Dose Rate (PDR) in cervical cancer regarding the discontinuation of the afterloading system used for the LDR treatments at our Institution since December 2009. In the first phase we studied the influence of the pulse dose and the pulse time in the biological equivalence between LDR and PDR treatments using the Linear Quadratic Model (LQM). In the second phase, the equivalent dose in 2 Gy/fraction (EQD(2)) for the tumor, rectum and bladder in treatments performed with both techniques was evaluated and statistically compared. All evaluated patients had stage IIB cervical cancer and were treated with External Beam Radiotherapy (EBRT) plus two Brachytherapy (BT) applications. Data were collected from 48 patients (26 patients treated with LDR and 22 patients with PDR). In the analyses of the influence of PDR parameters in the biological equivalence between LDR and PDR treatments (Phase 1), it was calculated that if the pulse dose in PDR was kept equal to the LDR dose rate, a small the-rapeutic loss was expected. If the pulse dose was decreased, the therapeutic window became larger, but a correction in the prescribed dose was necessary. In PDR schemes with 1 hour interval between pulses, the pulse time did not influence significantly the equivalent dose. In the comparison between the groups treated with LDR and PDR (Phase 2) we concluded that they were not equivalent, because in the PDR group the total EQD(2) for the tumor, rectum and bladder was smaller than in the LDR group; the LQM estimated that a correction in the prescribed dose of 6% to 10% was ne-cessary to avoid therapeutic loss. A correction in the prescribed dose was necessary; this correction should be achieved by calculating the PDR dose equivalent to the desired LDR total dose.

Biological equivalence between LDR and PDR in cervical cancer: multifactor analysis using the linear-quadratic model

PubMed Central

Bravo, Isabel; Pirraco, Rui

2011-01-01

Purpose The purpose of this work was the biological comparison between Low Dose Rate (LDR) and Pulsed Dose Rate (PDR) in cervical cancer regarding the discontinuation of the afterloading system used for the LDR treatments at our Institution since December 2009. Material and methods In the first phase we studied the influence of the pulse dose and the pulse time in the biological equivalence between LDR and PDR treatments using the Linear Quadratic Model (LQM). In the second phase, the equivalent dose in 2 Gy/fraction (EQD2) for the tumor, rectum and bladder in treatments performed with both techniques was evaluated and statistically compared. All evaluated patients had stage IIB cervical cancer and were treated with External Beam Radiotherapy (EBRT) plus two Brachytherapy (BT) applications. Data were collected from 48 patients (26 patients treated with LDR and 22 patients with PDR). Results In the analyses of the influence of PDR parameters in the biological equivalence between LDR and PDR treatments (Phase 1), it was calculated that if the pulse dose in PDR was kept equal to the LDR dose rate, a small the-rapeutic loss was expected. If the pulse dose was decreased, the therapeutic window became larger, but a correction in the prescribed dose was necessary. In PDR schemes with 1 hour interval between pulses, the pulse time did not influence significantly the equivalent dose. In the comparison between the groups treated with LDR and PDR (Phase 2) we concluded that they were not equivalent, because in the PDR group the total EQD2 for the tumor, rectum and bladder was smaller than in the LDR group; the LQM estimated that a correction in the prescribed dose of 6% to 10% was ne-cessary to avoid therapeutic loss. Conclusions A correction in the prescribed dose was necessary; this correction should be achieved by calculating the PDR dose equivalent to the desired LDR total dose. PMID:23346123

Evaluation Of Shielding Efficacy Of A Ferrite Containing Ceramic Material

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

Verst, C.

2015-10-12

The shielding evaluation of the ferrite based Mitsuishi ceramic material has produced for several radiation sources and possible shielding sizes comparative dose attenuation measurements and simulated projections. High resolution gamma spectroscopy provided uncollided and scattered photon spectra at three energies, confirming theoretical estimates of the ceramic’s mass attenuation coefficient, μ/ρ. High level irradiation experiments were performed using Co-60, Cs-137, and Cf-252 sources to measure penetrating dose rates through steel, lead, concrete, and the provided ceramic slabs. The results were used to validate the radiation transport code MCNP6 which was then used to generate dose rate attenuation curves as a functionmore » of shielding material, thickness, and mass for photons and neutrons ranging in energy from 200 keV to 2 MeV.« less

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

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

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

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

Efficacy evaluation of low-dose aspirin in IVF/ICSI patients evidence from 13 RCTs: A systematic review and meta-analysis.

PubMed

Wang, Liping; Huang, Xiaman; Li, Xueli; Lv, Fang; He, Xiao; Pan, Yu; Wang, Li; Zhang, Xiaomei

2017-09-01

We conducted a systematic review and meta-analysis of existing literature to evaluate the different outcomes of low-dose aspirin on patients undergoing in vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI), including clinical pregnancy rate, implantation rate, live birth rate, miscarriage rate, fertilization rate, number of oocytes retrieved, and so forth. Electronic databases including PubMed, MEDLINE, and Embase were searched between 1997 and March 2016 to identity eligible studies. The following comparisons between treatment groups were included: aspirin versus placebo; aspirin versus control group; aspirin versus aspirin + prednisolone + control. Thirteen randomized controlled trials which included 3104 participants were selected. There were no significant differences in implantation rate (RR = 1.15; 95% CI = 0.78-1.70), live birth rate (RR = 1.06; 95% CI = 0.93-1.21), miscarriage rate (RR = 1.28; 95% CI = 0.93-1.77), fertilization rate (RR = 0.91; 95% CI = 0.75-1.11), and endometrial thickness (WMD = 0.15; 95% CI = -0.38-0.67). But the research showed that aspirin treatment may improve the clinical pregnancy rate (RR = 1.16; 95% CI = 1.04-1.28) compared to placebo or no treatment, and reduce the number of oocytes retrieved (WMD = -0.68; 95% CI = -0.91-0.46). Our findings suggest that low-dose aspirin may improve the pregnancy rate in IVF/ICSI, with the recommended clinical use dose of 100 mg/day. Considering the limitation of included studies, further well-designed large-scaled RCTs are necessary to clarify whether aspirin may improve assisted reproduction outcomes in IVF/ICSI patients.

SU-E-J-169: The Dosimetric and Temporal Effects of Respiratory-Gated Radiation Therapy in Lung Cancer Patients

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

Rouabhi, O; Gross, B; Xia, J

2015-06-15

Purpose: To evaluate the dosimetric and temporal effects of high dose rate treatment mode for respiratory-gated radiation therapy in lung cancer patients. Methods: Treatment plans from five lung cancer patients (3 nongated (Group 1), 2 gated at 80EX-80IN (Group 2)) were retrospectively evaluated. The maximum tumor motions range from 6–12 mm. Using the same planning criteria, four new treatment plans, corresponding to four gating windows (20EX–20IN, 40EX–40IN, 60EX–60IN, and 80EX–80IN), were generated for each patient. Mean tumor dose (MTD), mean lung dose (MLD), and lung V20 were used to assess the dosimetric effects. A MATLAB algorithm was developed to computemore » treatment time by considering gantry rotation time, time to position collimator leaves, dose delivery time (scaled relative to the gating window), and communication overhead. Treatment delivery time for each plan was estimated using a 500 MU/min dose rate for the original plans and a 1500 MU/min dose rate for the gated plans. Results: Differences in MTD were less than 1Gy across plans for all five patients. MLD and lung V20 were on average reduced between −16.1% to −6.0% and −20.0% to −7.2%, respectively for non-gated plans when compared with the corresponding gated plans, and between − 5.8% to −4.2% and −7.0% to −5.4%, respectively for plans originally gated at 80EX–80IN when compared with the corresponding 20EX-20IN to 60EX– 60IN gated plans. Treatment delivery times of gated plans using high dose rate were reduced on average between −19.7% (−1.9min) to −27.2% (−2.7min) for originally non-gated plans and −15.6% (−0.9min) to −20.3% (−1.2min) for originally 80EX-80IN gated plans. Conclusion: Respiratory-gated radiation therapy in lung cancer patients can reduce lung toxicity, while maintaining tumor dose. Using a gated high-dose-rate treatment, delivery time comparable to non-gated normal-dose-rate treatment can be achieved. This research is supported by Siemens Medical Solutions USA, Inc.« less

Efficacy of a novel formulation of metaflumizone plus amitraz for the treatment of sarcoptic mange in dogs.

PubMed

Fourie, L J; Kok, D J; du Plessis, A; Rugg, D

2007-12-15

A novel spot-on formulation containing metaflumizone plus amitraz (ProMeris/ProMeris Duo for Dogs, Fort Dodge Animal Health, Overland Park, KS) was evaluated for efficacy against sarcoptic mange mites in naturally infested dogs. Sixteen dogs were allocated to two equal groups and were housed individually. Eight of the dogs were treated topically with metaflumizone plus amitraz at the proposed minimum dose rate (20mg/kg of each of metaflumizone and amitraz, at a dose volume of 0.133ml/kg) on Days 0 and 28. The other eight were treated with metaflumizone plus amitraz at the proposed minimum dose rate on Days 0, 14, 28 and 42. To enumerate Sarcoptes scabiei mites, skin scrapings were taken on each of Days 2, 14, 28, 42 and 56. Clinical signs of mange and the extent of sarcoptic lesions were evaluated on each dog when scrapings were made. Evaluation of the efficacy of the treatment was based on the absence of mites supported by the absence of clinical signs associated with canine sarcoptic mange. Treatment with metaflumizone plus amitraz at the minimum proposed dose rate at monthly (two treatments) or two-weekly (four treatments) intervals resulted in a rapid reduction of mites and improved clinical signs. The overall cure rates at Day 56, based on zero mite counts and/or resolution of clinical signs were 75% and 83% of dogs for the monthly and two-weekly regimens, respectively.

Exclusive low-dose-rate brachytherapy in 279 patients with T2N0 mobile tongue carcinoma

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

Bourgier, Celine; Coche-Dequeant, Bernard; Fournier, Charles

2005-10-01

Purpose: To evaluate the therapeutic results obtained with {sup 192}Ir low-dose-rate interstitial brachytherapy in T2N0 mobile tongue carcinoma. Patients and Methods: Between December 1979 and January 1998, 279 patients with T2N0 mobile tongue carcinoma were treated by exclusive low-dose-rate brachytherapy, with or without neck dissection. {sup 192}Ir brachytherapy was performed according to the 'Paris system' with a median total dose of 60 Gy (median dose rate, 0.5 Gy/h). Results: Overall survival was 74.3% and 46.6% at 2 and 5 years. Local control was 79.1% at 2 years and regional control, respectively, 75.9% and 69.5% at 2 and 5 years (Kaplan-Meiermore » method). Systematic dissection revealed 44.6% occult node metastases, and histologic lymph node involvement was identified as the main significant factor for survival. Complication rate was 16.5% (Grade 3, 2.9%). Half of the patients presented previous and/or successive malignant tumor (ear-nose-throat, esophagus, or bronchus). Conclusion: Exclusive low-dose-rate brachytherapy is an effective treatment for T2 tongue carcinoma. Regional control and survival are excellent in patients undergoing systematic neck dissection, which is mandatory in our experience because of a high rate of occult lymph node metastases.« less

Spiromax, a New Dry Powder Inhaler: Dose Consistency under Simulated Real-World Conditions.

PubMed

Canonica, Giorgio Walter; Arp, Jan; Keegstra, Johan René; Chrystyn, Henry

2015-10-01

Spiromax(®) is a novel dry powder inhaler for patients with asthma or chronic obstructive pulmonary disease (COPD). The studies presented here provide further data on attributes (in vitro dosing consistency with budesonide-formoterol (DuoResp) Spiromax; flow rates through empty versions of the Spiromax and Turbuhaler inhaler) of importance to patients with asthma or COPD. Dose-delivery studies were performed using low-, middle-, and high-strength DuoResp Spiromax. Dose consistency was assessed over inhaler life. Total emitted doses (TEDs) were measured at various flow rates, after exposure to high and low temperature or humidity, at different inhaler orientations, and after dropping the inhaler. The criterion for evaluating dose uniformity was whether mean TEDs were within the product specification limits. In separate studies, flow rates were measured after training, using the patient information leaflets, and again after enhanced training as part of a randomized, open-label, cross-over study. Mean values for both budesonide and formoterol were within 85%-115% of the label claim for each strength of DuoResp Spiromax for initial dose uniformity and for the other investigated conditions (temperature, humidity, orientation, dropping, knocking), with the exception of approximately an 80% increase in first dose after dropping the inhaler (subsequent doses not affected). In the flow rate patient study, two patients' inhalations with Spiromax and six with Turbuhaler were <30 L/min. The majority of asthma patients [91% (Spiromax) versus 82% (Turbuhaler)] achieved the preferred flow rate of >60 L/min. DuoResp Spiromax consistently meets dose uniformity criteria, under controlled laboratory conditions and with variations intended to mimic real-world use. Following enhanced training, all patients in the flow study were able to achieve the minimal inspiratory flow rate of >30 L/min, which is required for effective treatment.

Evaluation of a single-scan protocol for radiochromic film dosimetry.

PubMed

Shimohigashi, Yoshinobu; Araki, Fujio; Maruyama, Masato; Nakaguchi, Yuji; Kuwahara, Satoshi; Nagasue, Nozomu; Kai, Yudai

2015-03-08

The purpose of this study was to evaluate a single-scan protocol using Gafchromic EBT3 film (EBT3) by comparing it with the commonly used 24-hr measurement protocol for radiochromic film dosimetry. Radiochromic film is generally scanned 24 hr after film exposure (24-hr protocol). The single-scan protocol enables measurement results within a short time using only the verification film, one calibration film, and unirradiated film. The single-scan protocol was scanned 30 min after film irradiation. The EBT3 calibration curves were obtained with the multichannel film dosimetry method. The dose verifications for each protocol were performed with the step pattern, pyramid pattern, and clinical treatment plans for intensity-modulated radiation therapy (IMRT). The absolute dose distributions for each protocol were compared with those calculated by the treatment planning system (TPS) using gamma evaluation at 3% and 3 mm. The dose distribution for the single-scan protocol was within 2% of the 24-hr protocol dose distribution. For the step pattern, the absolute dose discrepancies between the TPS for the single-scan and 24-hr protocols were 2.0 ± 1.8 cGy and 1.4 ± 1.2 cGy at the dose plateau, respectively. The pass rates were 96.0% for the single-scan protocol and 95.9% for the 24-hr protocol. Similarly, the dose discrepancies for the pyramid pattern were 3.6 ± 3.5cGy and 2.9 ± 3.3 cGy, respectively, while the pass rates for the pyramid pattern were 95.3% and 96.4%, respectively. The average pass rates for the four IMRT plans were 96.7% ± 1.8% for the single-scan protocol and 97.3% ± 1.4% for the 24-hr protocol. Thus, the single-scan protocol measurement is useful for dose verification of IMRT, based on its accuracy and efficiency.

Evaluation of a single‐scan protocol for radiochromic film dosimetry

PubMed Central

Araki, Fujio; Maruyama, Masato; Nakaguchi, Yuji; Kuwahara, Satoshi; Nagasue, Nozomu; Kai, Yudai

2015-01-01

The purpose of this study was to evaluate a single‐scan protocol using Gafchromic EBT3 film (EBT3) by comparing it with the commonly used 24‐hr measurement protocol for radiochromic film dosimetry. Radiochromic film is generally scanned 24 hr after film exposure (24‐hr protocol). The single‐scan protocol enables measurement results within a short time using only the verification film, one calibration film, and unirradiated film. The single‐scan protocol was scanned 30 min after film irradiation. The EBT3 calibration curves were obtained with the multichannel film dosimetry method. The dose verifications for each protocol were performed with the step pattern, pyramid pattern, and clinical treatment plans for intensity‐modulated radiation therapy (IMRT). The absolute dose distributions for each protocol were compared with those calculated by the treatment planning system (TPS) using gamma evaluation at 3% and 3 mm. The dose distribution for the single‐scan protocol was within 2% of the 24‐hr protocol dose distribution. For the step pattern, the absolute dose discrepancies between the TPS for the single‐scan and 24‐hr protocols were 2.0±1.8 cGy and 1.4±1.2 cGy at the dose plateau, respectively. The pass rates were 96.0% for the single‐scan protocol and 95.9% for the 24‐hr protocol. Similarly, the dose discrepancies for the pyramid pattern were 3.6±3.5 cGy and 2.9±3.3 cGy, respectively, while the pass rates for the pyramid pattern were 95.3% and 96.4%, respectively. The average pass rates for the four IMRT plans were 96.7%±1.8% for the single‐scan protocol and 97.3%±1.4% for the 24‐hr protocol. Thus, the single‐scan protocol measurement is useful for dose verification of IMRT, based on its accuracy and efficiency. PACS number: 87.55.Qr PMID:26103194

Effect of ketamine dose on self-rated dissociation in patients with treatment refractory anxiety disorders.

PubMed

Castle, Cameron; Gray, Andrew; Neehoff, Shona; Glue, Paul

2017-10-01

Patients receiving ketamine for refractory depression and anxiety report dissociative symptoms in the first 60 min post-dose. The most commonly used instrument to assess this is the Clinician-Administered Dissociative States Scale (CADSS), developed based on the assessment of patients with dissociative symptoms. Its psychometric properties for ketamine-induced dissociation have not been reported. We evaluated these from a study using 0.25-1 mg/kg ketamine and midazolam (as an active control) in 18 patients with treatment-resistant anxiety. Dissociation ratings were increased by ketamine in a dose-dependent manner. In contrast, midazolam showed no effect on ratings of dissociation. For individual CADSS items, the magnitude of change and the ketamine dose at which changes were observed were not homogenous. The Cronbach alpha for the total scale was high (0.937), with acceptable item-rest correlations for almost all individual items. Purposefully removing items to maximise alpha did not lead to meaningful improvements. Acceptable internal consistency was still observed after removing items which lacked evidence of responsiveness at lower doses. The high Cronbach alpha values identified in this study suggests that the CADSS is an internally consistent instrument for evaluating ketamine-induced dissociation in clinical trials in anxiety, although it does not capture symptoms such as thought disorder.

Quantitative evaluation of patient-specific quality assurance using online dosimetry system

NASA Astrophysics Data System (ADS)

Jung, Jae-Yong; Shin, Young-Ju; Sohn, Seung-Chang; Min, Jung-Whan; Kim, Yon-Lae; Kim, Dong-Su; Choe, Bo-Young; Suh, Tae-Suk

2018-01-01

In this study, we investigated the clinical performance of an online dosimetry system (Mobius FX system, MFX) by 1) dosimetric plan verification using gamma passing rates and dose volume metrics and 2) error-detection capability evaluation by deliberately introduced machine error. Eighteen volumetric modulated arc therapy (VMAT) plans were studied. To evaluate the clinical performance of the MFX, we used gamma analysis and dose volume histogram (DVH) analysis. In addition, to evaluate the error-detection capability, we used gamma analysis and DVH analysis utilizing three types of deliberately introduced errors (Type 1: gantry angle-independent multi-leaf collimator (MLC) error, Type 2: gantry angle-dependent MLC error, and Type 3: gantry angle error). A dosimetric verification comparison of physical dosimetry system (Delt4PT) and online dosimetry system (MFX), gamma passing rates of the two dosimetry systems showed very good agreement with treatment planning system (TPS) calculation. For the average dose difference between the TPS calculation and the MFX measurement, most of the dose metrics showed good agreement within a tolerance of 3%. For the error-detection comparison of Delta4PT and MFX, the gamma passing rates of the two dosimetry systems did not meet the 90% acceptance criterion with the magnitude of error exceeding 2 mm and 1.5 ◦, respectively, for error plans of Types 1, 2, and 3. For delivery with all error types, the average dose difference of PTV due to error magnitude showed good agreement between calculated TPS and measured MFX within 1%. Overall, the results of the online dosimetry system showed very good agreement with those of the physical dosimetry system. Our results suggest that a log file-based online dosimetry system is a very suitable verification tool for accurate and efficient clinical routines for patient-specific quality assurance (QA).

The dose effects of short-term dronabinol (oral THC) maintenance in daily cannabis users.

PubMed

Vandrey, Ryan; Stitzer, Maxine L; Mintzer, Miriam Z; Huestis, Marilyn A; Murray, Jeannie A; Lee, Dayong

2013-02-01

Prior studies have separately examined the effects of dronabinol (oral THC) on cannabis withdrawal, cognitive performance, and the acute effects of smoked cannabis. A single study examining these clinically relevant domains would benefit the continued evaluation of dronabinol as a potential medication for the treatment of cannabis use disorders. Thirteen daily cannabis smokers completed a within-subject crossover study and received 0, 30, 60 and 120mg dronabinol per day for 5 consecutive days. Vital signs and subjective ratings of cannabis withdrawal, craving and sleep were obtained daily; outcomes under active dose conditions were compared to those obtained under placebo dosing. On the 5th day of medication maintenance, participants completed a comprehensive cognitive performance battery and then smoked five puffs of cannabis for subjective effects evaluation. Each dronabinol maintenance period occurred in a counterbalanced order and was separated by 9 days of ad libitum cannabis use. Dronabinol dose-dependently attenuated cannabis withdrawal and resulted in few adverse side effects or decrements in cognitive performance. Surprisingly, dronabinol did not alter the subjective effects of smoked cannabis, but cannabis-induced increases in heart rate were attenuated by the 60 and 120mg doses. Dronabinol's ability to dose-dependently suppress cannabis withdrawal may be therapeutically beneficial to individuals trying to stop cannabis use. The absence of gross cognitive impairment or side effects in this study supports safety of doses up to 120mg/day. Continued evaluation of dronabinol in targeted clinical studies of cannabis treatment, using an expanded range of doses, is warranted. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

The Dose Effects of Short-Term Dronabinol (Oral THC) Maintenance in Daily Cannabis Users

PubMed Central

Vandrey, Ryan; Stitzer, Maxine L.; Mintzer, Miriam Z.; Huestis, Marilyn A.; Murray, Jeannie A.; Lee, Dayong

2012-01-01

BACKGROUND Prior studies have separately examined the effects of dronabinol (oral THC) on cannabis withdrawal, cognitive performance, and the acute effects of smoked cannabis. A single study examining these clinically relevant domains would benefit the continued evaluation of dronabinol as a potential medication for the treatment of cannabis use disorders. METHODS Thirteen daily cannabis smokers completed a within-subject crossover study and received 0, 30, 60 and 120 mg dronabinol per day for 5 consecutive days. Vital signs and subjective ratings of cannabis withdrawal, craving and sleep were obtained daily; outcomes under active dose conditions were compared to those obtained under placebo dosing. On the 5th day of medication maintenance, participants completed a comprehensive cognitive performance battery and then smoked 5 puffs of cannabis for subjective effects evaluation. Each dronabinol maintenance period occurred in a counterbalanced order and was separated by 9 days of ad-libitum cannabis use. RESULTS Dronabinol dose-dependently attenuated cannabis withdrawal and resulted in few adverse side effects or decrements in cognitive performance. Surprisingly, dronabinol did not alter the subjective effects of smoked cannabis, but cannabis-induced increases in heart rate were attenuated by the 60 and 120 mg doses. CONCLUSIONS Dronabinol’s ability to dose-dependently suppress cannabis withdrawal may be therapeutically beneficial to individuals trying to stop cannabis use. The absence of gross cognitive impairment or side effects in this study supports safety of doses up to 120mg per day. Continued evaluation of dronabinol in targeted clinical studies of cannabis treatment, using an expanded range of doses, is warranted. PMID:22921474

Shielding from Solar Particle Event Exposures in Deep Space

NASA Technical Reports Server (NTRS)

Wilson, John W.; Cucinotta, F. A.; Shinn, J. L.; Simonsen, L. C.; Dubey, R. R.; Jordan, W. R.; Jones, T. D.; Chang, C. K.; Kim, M. Y.

1999-01-01

The physical composition and intensities of solar particle event exposures or sensitive astronaut tissues are examined under conditions approximating an astronaut in deep space. Response functions for conversion of particle fluence into dose and dose equivalent averaged over organ tissue, are used to establish significant fluence levels and the expected dose and dose rates of the most important events from past observations. The BRYNTRN transport code is used to evaluate the local environment experienced by sensitive tissues and used to evaluate bioresponse models developed for use in tactical nuclear warfare. The present results will help to the biophysical aspects of such exposure in the assessment of RBE and dose rate effects and their impact on design of protection systems for the astronauts. The use of polymers as shielding material in place of an equal mass of aluminum would prowide a large safety factor without increasing the vehicle mass. This safety factor is sufficient to provide adequate protection if a factor of two larger event than has ever been observed in fact occurs during the mission.

Sensory evaluation by gamma radiation effect on protein allergen of laying hen eggs

NASA Astrophysics Data System (ADS)

Harder, M. N. C.; Arthur, V.; Perina, V. C. S.; Silva, L. C. A. S.; Bortoleto, G. G.

2012-08-01

Although considered the most complete food and nutritionally shown to be part of a healthy diet, the egg is the source of many eating disorders, especially for infants. Irradiation has been used in studies not only as a means of microbiological control, but also on its structural action in the substances molecules and has been used to reduce the allergenic effects. The aim of this study was to evaluate the sensory effects of Co60 gamma radiation on proteins, enabling the acceptability of allergy food for genetically intolerant people. Eggs commercial fresh and freeze-dried and subjected to gamma irradiation by Co60 source at doses 0 (control), 10 kGy; 20 kGy and 30 kGy and rates of doses of 19.4 kGy/h and 31.8 kGy/h. Acceptability test was used by the hedonic scale, since it is necessary to know the "affective status" of consumers for the product, implying a preference, i.e. the most preferred samples are the most accepted and vice versa. The samples were presented as the habit of consumption (cooked) to a group of 41 adults panelists of both gender, aged from 21 to 40 years, and served under complete block design balanced with respect to the order of presentation. The evaluated attributes was flavor, appearance and overall acceptability. In general, for boiled eggs and freeze-dried, it was observed that the control sample was the most acceptable, followed by the sample irradiated with 10 kGy in both dose rates. In addition, panelists presented in testimony that they found interesting changes due to irradiation; also said they would not buy the product because of the marked change in appearance and smell, which at one point he ended up in disgust and detract from sales of the product, but they would buy irradiated with 10 kGy in both dose rate and dose of 20 kGy at a dose rate of 19.4 kGy/h.

A dose-response study of dexmedetomidine administered as the primary sedative in infants following open heart surgery.

PubMed

Su, Felice; Nicolson, Susan C; Zuppa, Athena F

2013-06-01

To evaluate the dose-response relationship of dexmedetomidine in infants with congenital heart disease postoperative from open heart surgery. Prospective open-label dose-escalation pharmacokinetic-pharmacodynamic study. Tertiary pediatric cardiac ICU. Thirty-six evaluable infants, 1-24 months old, postoperative from open heart surgery requiring mechanical ventilation. Cohorts of 12 infants were enrolled sequentially to one of the three IV loading doses of dexmedetomidine (0.35, 0.7, and 1 mcg/kg) over 10 minutes followed by respective continuous infusions (0.25, 0.5, and 0.75 mcg/kg/hr) for up to 24 hours. Dexmedetomidine plasma concentrations were obtained at timed intervals during and following discontinuation of infusion. Pharmacodynamic variables evaluated included sedation scores, supplemental sedation and analgesia medication administration, time to tracheal extubation, respiratory function, and hemodynamic parameters. Infants achieved a deeper sedation measured by the University of Michigan Sedation Scale score (2.6 vs 1) despite requiring minimal supplemental sedation (0 unit doses/hr) and fewer analgesic medications (0.07 vs 0.15 unit doses/hr) while receiving dexmedetomidine compared with the 12-hour follow-up period. Thirty-one patients were successfully extubated while receiving the dexmedetomidine infusion. Only one patient remained intubated due to oversedation during the infusion. While receiving dexmedetomidine, there was a decrease in heart rate compared with baseline, 132 versus 161 bpm, but there was an increase in heart rate compared with postinfusion values, 132 versus 128 bpm. There was no statistically or clinically significant change in mean arterial blood pressure. Dexmedetomidine administration in infants following open heart surgery can provide improved sedation with reduction in supplemental medication requirements, leading to successful extubation while receiving a continuous infusion. The postoperative hemodynamic changes that occur in infants postoperative from open heart surgery are multifactorial. Although dexmedetomidine may play a role in decreasing heart rate immediately postoperative, the changes were not clinically significant and did not fall below postinfusion heart rates.

Dose and dose rate effects of whole-body proton irradiation on leukocyte populations and lymphoid organs: part I

NASA Technical Reports Server (NTRS)

Gridley, Daila S.; Pecaut, Michael J.; Dutta-Roy, Radha; Nelson, Gregory A.

2002-01-01

The goal of part I of this study was to evaluate the effects of whole-body proton irradiation on lymphoid organs and specific leukocyte populations. C57BL/6 mice were exposed to the entry region of the proton Bragg curve to total doses of 0.5 gray (Gy), 1.5 Gy, and 3.0 Gy, each delivered at a low dose rate (LDR) of 1 cGy/min and high dose rate (HDR) of 80 cGy/min. Non-irradiated and 3 Gy HDR gamma-irradiated groups were included as controls. At 4 days post-irradiation, highly significant radiation dose-dependent reductions were observed in the mass of both lymphoid organs and the numbers of leukocytes and T (CD3(+)), T helper (CD3(+)/CD4(+)), T cytotoxic (CD3(+)/CD8(+)), and B (CD19(+)) cells in both blood and spleen. A less pronounced dose effect was noted for natural killer (NK1.1(+) NK) cells in spleen. Monocyte, but not granulocyte, counts in blood were highly dose-dependent. The numbers for each population generally tended to be lower with HDR than with LDR radiation; a significant dose rate effect was found in the percentages of T and B cells, monocytes, and granulocytes and in CD4(+):CD8(+) ratios. These data indicate that mononuclear cell response to the entry region of the proton Bragg curve is highly dependent upon the total dose and that dose rate effects are evident with some cell types. Results from gamma- and proton-irradiated groups (both at 3 Gy HDR) were similar, although proton-irradiation gave consistently lower values in some measurements.

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

SU-E-T-184: Clinical VMAT QA Practice Using LINAC Delivery Log Files

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

Johnston, H; Jacobson, T; Gu, X

2015-06-15

Purpose: To evaluate the accuracy of volumetric modulated arc therapy (VMAT) treatment delivery dose clouds by comparing linac log data to doses measured using an ionization chamber and film. Methods: A commercial IMRT quality assurance (QA) process utilizing a DICOM-RT framework was tested for clinical practice using 30 prostate and 30 head and neck VMAT plans. Delivered 3D VMAT dose distributions were independently checked using a PinPoint ionization chamber and radiographic film in a solid water phantom. DICOM RT coordinates were used to extract the corresponding point and planar doses from 3D log file dose distributions. Point doses were evaluatedmore » by computing the percent error between log file and chamber measured values. A planar dose evaluation was performed for each plan using a 2D gamma analysis with 3% global dose difference and 3 mm isodose point distance criteria. The same analysis was performed to compare treatment planning system (TPS) doses to measured values to establish a baseline assessment of agreement. Results: The mean percent error between log file and ionization chamber dose was 1.0%±2.1% for prostate VMAT plans and −0.2%±1.4% for head and neck plans. The corresponding TPS calculated and measured ionization chamber values agree within 1.7%±1.6%. The average 2D gamma passing rates for the log file comparison to film are 98.8%±1.0% and 96.2%±4.2% for the prostate and head and neck plans, respectively. The corresponding passing rates for the TPS comparison to film are 99.4%±0.5% and 93.9%±5.1%. Overall, the point dose and film data indicate that log file determined doses are in excellent agreement with measured values. Conclusion: Clinical VMAT QA practice using LINAC treatment log files is a fast and reliable method for patient-specific plan evaluation.« less

Acute Hematological Effects in Mice Exposed to the Expected Doses, Dose-rates, and Energies of Solar Particle Event-like Proton Radiation

PubMed Central

Sanzari, Jenine K.; Cengel, Keith A.; Wan, X. Steven; Rusek, Adam; Kennedy, Ann R.

2014-01-01

NASA has funded several projects that have provided evidence for the radiation risk in space. One radiation concern arises from solar particle event (SPE) radiation, which is composed of energetic electrons, protons, alpha particles and heavier particles. SPEs are unpredictable and the accompanying SPE radiation can place astronauts at risk of blood cell death, contributing to a weakened immune system and increased susceptibility to infection. The doses, dose rates, and energies of the proton radiation expected to occur during a SPE have been simulated at the NASA Space Radiation Laboratory, Brookhaven National Laboratory, delivering total body doses to mice. Hematological values were evaluated at acute time points, up to 24 hrs. post-radiation exposure. PMID:25202654

Identifying the most successful dose (MSD) in dose-finding studies in cancer.

PubMed

Zohar, Sarah; O'Quigley, John

2006-01-01

For a dose finding study in cancer, the most successful dose (MSD), among a group of available doses, is that dose at which the overall success rate is the highest. This rate is the product of the rate of seeing non-toxicities together with the rate of tumor response. A successful dose finding trial in this context is one where we manage to identify the MSD in an efficient manner. In practice we may also need to consider algorithms for identifying the MSD which can incorporate certain restrictions, the most common restriction maintaining the estimated toxicity rate alone below some maximum rate. In this case the MSD may correspond to a different level than that for the unconstrained MSD and, in providing a final recommendation, it is important to underline that it is subject to the given constraint. We work with the approach described in O'Quigley et al. [Biometrics 2001; 57(4):1018-1029]. The focus of that work was dose finding in HIV where both information on toxicity and efficacy were almost immediately available. Recent cancer studies are beginning to fall under this same heading where, as before, toxicity can be quickly evaluated and, in addition, we can rely on biological markers or other measures of tumor response. Mindful of the particular context of cancer, our purpose here is to consider the methodology developed by O'Quigley et al. and its practical implementation. We also carry out a study on the doubly under-parameterized model, developed by O'Quigley et al. but not

Evaluation of GaAs low noise and power MMIC technologies to neutron, ionizing dose and dose rate effects

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

Derewonko, H.; Bosella, A.; Pataut, G.

1996-06-01

An evaluation program of Thomson CSF-TCS GaAs low noise and power MMIC technologies to 1 MeV equivalent neutron fluence levels, up to 1 {times} 10{sup 15} n/cm{sup 2}, ionizing 1.17--1.33 MeV CO{sup 60} dose levels in excess of 200 Mrad(GaAs) and dose rate levels reaching 1.89 {times} 10{sup 11} rad(GaAs)/s is presented in terms of proper components and parameter choices, DC/RF electrical measurements and test methods under irradiation. Experimental results are explained together with drift analyses of electrical parameters that have determined threshold limits of component degradations. Modelling the effects of radiation on GaAs components relies on degradation analysis ofmore » active layer which appears to be the most sensitive factor. MMICs degradation under neutron fluence was simulated from irradiated FET data. Finally, based on sensitivity of technological parameters, rad-hard design including material, technology and MMIC design enhancement is discussed.« less

AN EVALUATION OF THE BASIC CHARACTERISTICS OF A PLASTIC SCINTILLATING FIBRE DETECTOR IN CT RADIATION FIELDS.

PubMed

Terasaki, Kento; Fujibuchi, Toshioh; Toyoda, Takatoshi; Yoshida, Yutaka; Akasaka, Tsutomu; Nohtomi, Akihiro; Morishita, Junji

2016-12-01

The ionisation chamber for computed tomography (CT) is an instrument that is most commonly used to measure the computed tomography dose index. However, it has been reported that the 10 cm effective detection length of the ionisation chamber is insufficient due to the extent of the dose distribution outside the chamber. The purpose of this study was to estimate the basic characteristics of a plastic scintillating fibre (PSF) detector with a long detection length of 50 cm in CT radiation fields. The authors investigated position dependence using diagnostic X-ray equipment and dependencies for energy, dose rate and slice thickness using an X-ray CT system. The PSF detector outputs piled up at a count rate of 10 000 counts ms -1 in dose rate dependence study. With calibration, this detector may be useful as a CT dosemeter with a long detection length except for the measurement at high dose rate. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Optically Stimulated Luminescence Analysis Method for High Dose Rate Using an Optical Fiber Type Dosimeter

NASA Astrophysics Data System (ADS)

Ueno, Katsunori; Tominaga, Kazuo; Tadokoro, Takahiro; Ishizawa, Koji; Takahashi, Yoshinori; Kuwabara, Hitoshi

2016-08-01

The investigation of air dose rates at locations in the Fukushima Dai-ichi Nuclear Power Station is necessary for safe removal of the molten nuclear fuel. The target performance for the investigation is to analyze a dose rate in the range of 10-3 Gy/h to 102 Gy/h with a measurement precision of ±4.0% full scale (F.S.) at a measurement interval of 60 s. In order to achieve this target, the authors proposed an optically stimulated luminescence (OSL) analysis method using prompt OSL for a wide dynamic range of dose rates; the OSL is generated using BaFBr:Eu with a fast decay time constant. The luminescence intensity by prompt OSL was formulated by the electron concentration of the trapping state during gamma ray and stimulation light irradiations. The prototype OSL monitor using BaFBr:Eu was manufactured for investigation of prompt OSL and evaluation of the measurement precision. The time dependence of the luminescence intensity by prompt OSL was analyzed by irradiating the OSL sensor in a 60Co irradiation facility. The measured dose rates were obtained in a prompt mode and an accumulating mode with a precision of ±3.3% F.S. for the dose rate range of 9.5 ×10-4 Gy/h to 1.2 ×102 Gy/h.

The Study of External Dose Rate and Retained Body Activity of Patients Receiving 131I Therapy for Differentiated Thyroid Carcinoma

PubMed Central

Zhang, Haiying; Jiao, Ling; Cui, Songye; Wang, Liang; Tan, Jian; Zhang, Guizhi; He, Yajing; Ruan, Shuzhou; Fan, Saijun; Zhang, Wenyi

2014-01-01

Radiation safety is an integral part of targeted radionuclide therapy. The aim of this work was to study the external dose rate and retained body activity as functions of time in differentiated thyroid carcinoma patients receiving 131I therapy. Seventy patients were stratified into two groups: the ablation group (A) and the follow-up group (FU). The patients’ external dose rate was measured, and simultaneously, their retained body radiation activity was monitored at various time points. The equations of the external dose rate and the retained body activity, described as a function of hours post administration, were fitted. Additionally, the release time for patients was calculated. The reduction in activity in the group receiving a second or subsequent treatment was more rapid than the group receiving only the initial treatment. Most important, an expeditious method was established to indirectly evaluate the retained body activity of patients by measuring the external dose rate with a portable radiation survey meter. By this method, the calculated external dose rate limits are 19.2, 8.85, 5.08 and 2.32 μSv·h−1 at 1, 1.5, 2 and 3 m, respectively, according to a patient’s released threshold level of retained body activity <400 MBq. This study is beneficial for radiation safety decision-making. PMID:25337944

Individualized Radiation Dose Escalation Based on the Decrease in Tumor FDG Uptake and Normal Tissue Constraints Improve Survival in Patients With Esophageal Carcinoma.

PubMed

Ma, Jinbo; Wang, Zhaoyang; Wang, Chengde; Chen, Ercheng; Dong, Yaozong; Song, Yipeng; Wang, Wei; You, Dong; Jiang, Wei; Zang, Rukun

2017-02-01

To determine whether individualized radiation dose escalation after planned chemoradiation based on the decrease in tumor and normal tissue constraints can improve survival in patients with esophageal carcinoma. From August 2005 to December 2010, 112 patients with squamous esophageal carcinoma were treated with radical concurrent chemoradiation. Patients received positron emission tomography-computer tomography scan twice, before radiation and after radiation dose of 50.4 Gy. All patients were noncomplete metabolic response groups according to the Response Evaluation Criteria in solid tumors. Only 52 patients with noncomplete metabolic response received individualized dose escalation based on tumor and normal tissue constraints. Survival and treatment failure were observed and analyzed using SPSS (13.0). The rate of complete metabolic response for patients with noncomplete metabolic response after dose escalation reached 17.3% (9 of 52). The 2-year overall survival rates for patients with noncomplete metabolic response in the conventional and dose-escalation groups were 20.5% and 42.8%, respectively( P = .001). The 2-year local control rates for patients were 35.7% and 76.2%, respectively ( P = .002). When patients were classified into partial metabolic response and no metabolic response, 2-year overall survival rates for patients with partial metabolic response were significantly different in conventional and dose-escalation groups (33.8% vs 78.4%; P = .000). The 2-year overall survival rates for patients with no metabolic response in two groups (8.6% vs 15.1%) did not significantly differ ( P = .917). Individualized radiation dose escalation has the potential to improve survival in patients with esophageal carcinoma according to increased rate of complete metabolic response. However, further trials are needed to confirm this and to identify patients who may benefit from dose escalation.

Radiosensitivity study and radiation effects on morphology characterization of grey oyster mushroom Pleurotus sajor-caju

NASA Astrophysics Data System (ADS)

Rashid, Rosnani Abdul; Daud, Fauzi; Senafi, Sahidan; Awang, Mat Rasol; Mohamad, Azhar; Mutaat, Hassan Hamdani; Maskom, Mohd Meswan

2014-09-01

Radiosensitive dosage and morphology characterization of irradiated grey oyster mushroom Pleurotus sajor-caju by gamma rays was investigated due to effects of irradiation. In order to establish the effect, mycelium of P. sajor-caju was irradiated by gamma rays at dose 0.1 to 8.0 kGy with dose rate 0.227 Gy sec-1. The irradiation of mycelia was carried out at the radiation facility in Malaysian Nuclear Agency. The radiosensitivity study was performed by evaluating the percentage of survival irradiated mycelia. The lethal dose of the mycelium P. sajor-caju was determined at 4.0 kGy and LD50 to be equal at 2.2 kGy. The radiation effects on morphology were evaluated based on growth rate of irradiated mycelia, mycelia types, colonization period on substrate, morphology of fruit bodies and yields. The results shown growth rate of irradiated mycelium was slightly lower than the control and decreased as the dose increased. Irradiation was found can induced the primordia formation on PDA and the BE of irradiated seed is higher than to control. The irradiation is proven to be useful for generating new varieties of mushroom with commercial value to the industry.

Agreement between gamma passing rates using computed tomography in radiotherapy and secondary cancer risk prediction from more advanced dose calculated models

PubMed Central

Balosso, Jacques

2017-01-01

Background During the past decades, in radiotherapy, the dose distributions were calculated using density correction methods with pencil beam as type ‘a’ algorithm. The objectives of this study are to assess and evaluate the impact of dose distribution shift on the predicted secondary cancer risk (SCR), using modern advanced dose calculation algorithms, point kernel, as type ‘b’, which consider change in lateral electrons transport. Methods Clinical examples of pediatric cranio-spinal irradiation patients were evaluated. For each case, two radiotherapy treatment plans with were generated using the same prescribed dose to the target resulting in different number of monitor units (MUs) per field. The dose distributions were calculated, respectively, using both algorithms types. A gamma index (γ) analysis was used to compare dose distribution in the lung. The organ equivalent dose (OED) has been calculated with three different models, the linear, the linear-exponential and the plateau dose response curves. The excess absolute risk ratio (EAR) was also evaluated as (EAR = OED type ‘b’ / OED type ‘a’). Results The γ analysis results indicated an acceptable dose distribution agreement of 95% with 3%/3 mm. Although, the γ-maps displayed dose displacement >1 mm around the healthy lungs. Compared to type ‘a’, the OED values from type ‘b’ dose distributions’ were about 8% to 16% higher, leading to an EAR ratio >1, ranged from 1.08 to 1.13 depending on SCR models. Conclusions The shift of dose calculation in radiotherapy, according to the algorithm, can significantly influence the SCR prediction and the plan optimization, since OEDs are calculated from DVH for a specific treatment. The agreement between dose distribution and SCR prediction depends on dose response models and epidemiological data. In addition, the γ passing rates of 3%/3 mm does not translate the difference, up to 15%, in the predictions of SCR resulting from alternative algorithms. Considering that modern algorithms are more accurate, showing more precisely the dose distributions, but that the prediction of absolute SCR is still very imprecise, only the EAR ratio could be used to rank radiotherapy plans. PMID:28811995

Comparison of the Efficacy and Safety of Oritavancin Front-Loaded Dosing Regimens to Daily Dosing: an Analysis of the SIMPLIFI Trial ▿

PubMed Central

Dunbar, Lala M.; Milata, Joe; McClure, Ty; Wasilewski, Margaret M.

2011-01-01

Oritavancin is a novel lipoglycopeptide with demonstrated effectiveness against complicated skin and skin structure infections (cSSSI) caused by Gram-positive pathogens, including those caused by methicillin-resistant Staphylococcus aureus (MRSA). The pharmacokinetic and pharmacodynamic profile of oritavancin is favorable for single or infrequent dosing. A phase 2, multicenter, randomized, double-blind, parallel, active-comparator study (ClinicalTrials.gov identifier, NCT00514527) of single and infrequent dosing of intravenous (i.v.) oritavancin for the treatment of cSSSI caused by Gram-positive pathogens (wound infections, major abscess, and cellulitis) was undertaken to evaluate the noninferiority of front-loaded dosing regimens compared to a daily-dosing regimen. A total of 302 patients ≥18 years of age were randomized equally to one of three oritavancin treatment groups, receiving either a daily dose (200 mg) administered for 3 to 7 days, a single dose (1,200 mg), or an infrequent dose (800-mg dose, with the option for an additional 400 mg on day 5). The primary efficacy was defined as a clinical response in clinically evaluable (CE) patients assessed at days 21 to 29 (test of cure [TOC]). The cure rates in the CE population were 72.4% (55/76) in the daily-dose group, 81.5% (66/81) in the 1,200-mg-single-dose group, and 77.5% (55/71) in the infrequent-dose group. In patients with MRSA at baseline, the cure rates were 78.3% (18/23), 73.0% (27/37), and 87.0% (20/23) in the daily-, 1,200-mg-single-, and infrequent-dose groups, respectively; however, the study was not powered to assess outcomes in the MRSA subpopulation, and given the heterogeneity of the types of infection and the small sample size, these do not suggest any true differences in efficacy rates for these pathogens. The frequencies of adverse events were similar among treatment groups. The results of this study show that single- and infrequent-dosing schedules of oritavancin were as efficacious as daily administration and had a similar safety profile in treating cSSSI caused by Gram-positive pathogens, including MRSA. PMID:21537018

PARMA: PHITS-based Analytical Radiation Model in the Atmosphere--Verification of Its Accuracy in Estimating Cosmic Radiation Doses

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

Sato, Tatsuhiko; Satoh, Daiki; Endo, Akira

Estimation of cosmic-ray spectra in the atmosphere has been an essential issue in the evaluation of the aircrew doses. We therefore developed an analytical model that can predict the terrestrial neutron, proton, He nucleus, muon, electron, positron and photon spectra at altitudes below 20 km, based on the Monte Carlo simulation results of cosmic-ray propagation in the atmosphere performed by the PHITS code. The model was designated PARMA. In order to examine the accuracy of PARMA in terms of the neutron dose estimation, we measured the neutron dose rates at the altitudes between 20 to 10400 m, using our developedmore » dose monitor DARWIN mounted on an aircraft. Excellent agreement was observed between the measured dose rates and the corresponding data calculated by PARMA coupled with the fluence-to-dose conversion coefficients, indicating the applicability of the model to be utilized in the route-dose calculation.« less

Extra dose due to extravehicular activity during the NASA4 mission measured by an on-board TLD system.

PubMed

Deme, S; Apathy, I; Hejja, I; Lang, E; Feher, I

1999-01-01

A microprocessor-controlled on-board TLD system, 'Pille'96', was used during the NASA4 (1997) mission to monitor the cosmic radiation dose inside the Mir Space Station and to measure the extra dose to two astronauts in the course of their extravehicular activity (EVA). For the EVA dose measurements, CaSO4:Dy bulb dosemeters were located in specially designed pockets of the ORLAN spacesuits. During an EVA lasting 6 h, the dose ratio inside and outside Mir was measured. During the EVA, Mir crossed the South Atlantic Anomaly (SAA) three times. Taking into account the influence of these three crossings the mean EVA/internal dose rate ratio was 3.2. Internal dose mapping using CaSO4:Dy dosemeters gave mean dose rates ranging from 9.3 to 18.3 microGy h-1 at locations where the shielding effect was not the same. Evaluation results of the high temperature region of LiF dosemeters are given to estimate the mean LET.

SU-E-T-370: Evaluating Plan Quality and Dose Delivery Accuracy of Tomotherapy SBRT Treatments for Lung Cancer

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

Blake, S; Thwaites, D; Hansen, C

2015-06-15

Purpose: This study evaluated the plan quality and dose delivery accuracy of stereotactic body radiotherapy (SBRT) helical Tomotherapy (HT) treatments for lung cancer. Results were compared with those previously reported by our group for flattening filter (FF) and flattening filter free (FFF) VMAT treatments. This work forms part of an ongoing multicentre and multisystem planning and dosimetry audit on FFF beams for lung SBRT. Methods: CT datasets and DICOM RT structures delineating the target volume and organs at risk for 6 lung cancer patients were selected. Treatment plans were generated using the HT treatment planning system. Tumour locations were classifiedmore » as near rib, near bronchial tree or in free lung with prescribed doses of 48Gy/4fr, 50Gy/5fr and 54Gy/3fr respectively. Dose constraints were specified by a modified RTOG0915 protocol used for an Australian SBRT phase II trial. Plan quality was evaluated using mean PTV dose, PTV volume receiving 100% of the prescribed dose (V100%), target conformity (CI=VD100%/VPTV) and low dose spillage (LDS=VD50%/VPTV). Planned dose distributions were compared to those measured using an ArcCheck phantom. Delivery accuracy was evaluated using a gamma-index pass rate of 95% with 3% (of max dose) and 3mm criteria. Results: Treatment plans for all patients were clinically acceptable in terms of quality and accuracy of dose delivery. The following DVH metrics are reported as averages (SD) of all plans investigated: mean PTV dose was 115.3(2.4)% of prescription, V100% was 98.8(0.9)%, CI was 1.14(0.03) and LDS was 5.02(0.37). The plans had an average gamma-index passing rate of 99.3(1.3)%. Conclusion: The results reported in this study for HT agree within 1 SD to those previously published by our group for VMAT FF and FFF lung SBRT treatments. This suggests that HT delivers lung SBRT treatments of comparable quality and delivery accuracy as VMAT using both FF and FFF beams.« less

Statistical variability and confidence intervals for planar dose QA pass rates

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

Bailey, Daniel W.; Nelms, Benjamin E.; Attwood, Kristopher

Purpose: The most common metric for comparing measured to calculated dose, such as for pretreatment quality assurance of intensity-modulated photon fields, is a pass rate (%) generated using percent difference (%Diff), distance-to-agreement (DTA), or some combination of the two (e.g., gamma evaluation). For many dosimeters, the grid of analyzed points corresponds to an array with a low areal density of point detectors. In these cases, the pass rates for any given comparison criteria are not absolute but exhibit statistical variability that is a function, in part, on the detector sampling geometry. In this work, the authors analyze the statistics ofmore » various methods commonly used to calculate pass rates and propose methods for establishing confidence intervals for pass rates obtained with low-density arrays. Methods: Dose planes were acquired for 25 prostate and 79 head and neck intensity-modulated fields via diode array and electronic portal imaging device (EPID), and matching calculated dose planes were created via a commercial treatment planning system. Pass rates for each dose plane pair (both centered to the beam central axis) were calculated with several common comparison methods: %Diff/DTA composite analysis and gamma evaluation, using absolute dose comparison with both local and global normalization. Specialized software was designed to selectively sample the measured EPID response (very high data density) down to discrete points to simulate low-density measurements. The software was used to realign the simulated detector grid at many simulated positions with respect to the beam central axis, thereby altering the low-density sampled grid. Simulations were repeated with 100 positional iterations using a 1 detector/cm{sup 2} uniform grid, a 2 detector/cm{sup 2} uniform grid, and similar random detector grids. For each simulation, %/DTA composite pass rates were calculated with various %Diff/DTA criteria and for both local and global %Diff normalization techniques. Results: For the prostate and head/neck cases studied, the pass rates obtained with gamma analysis of high density dose planes were 2%-5% higher than respective %/DTA composite analysis on average (ranging as high as 11%), depending on tolerances and normalization. Meanwhile, the pass rates obtained via local normalization were 2%-12% lower than with global maximum normalization on average (ranging as high as 27%), depending on tolerances and calculation method. Repositioning of simulated low-density sampled grids leads to a distribution of possible pass rates for each measured/calculated dose plane pair. These distributions can be predicted using a binomial distribution in order to establish confidence intervals that depend largely on the sampling density and the observed pass rate (i.e., the degree of difference between measured and calculated dose). These results can be extended to apply to 3D arrays of detectors, as well. Conclusions: Dose plane QA analysis can be greatly affected by choice of calculation metric and user-defined parameters, and so all pass rates should be reported with a complete description of calculation method. Pass rates for low-density arrays are subject to statistical uncertainty (vs. the high-density pass rate), but these sampling errors can be modeled using statistical confidence intervals derived from the sampled pass rate and detector density. Thus, pass rates for low-density array measurements should be accompanied by a confidence interval indicating the uncertainty of each pass rate.« less

Biological effective dose evaluation in gynaecological brachytherapy: LDR and HDR treatments, dependence on radiobiological parameters, and treatment optimisation.

PubMed

Bianchi, C; Botta, F; Conte, L; Vanoli, P; Cerizza, L

2008-10-01

This study was undertaken to compare the biological efficacy of different high-dose-rate (HDR) and low-dose-rate (LDR) treatments of gynaecological lesions, to identify the causes of possible nonuniformity and to optimise treatment through customised calculation. The study considered 110 patients treated between 2001 and 2006 with external beam radiation therapy and/or brachytherapy with either LDR (afterloader Selectron, (137)Cs) or HDR (afterloader microSelectron Classic, (192)Ir). The treatments were compared in terms of biologically effective dose (BED) to the tumour and to the rectum (linear-quadratic model) by using statistical tests for comparisons between independent samples. The difference between the two treatments was statistically significant in one case only. However, within each technique, we identified considerable nonuniformity in therapeutic efficacy due to differences in fractionation schemes and overall treatment time. To solve this problem, we created a Microsoft Excel spreadsheet allowing calculation of the optimal treatment for each patient: best efficacy (BED(tumour)) without exceeding toxicity threshold (BED(rectum)). The efficacy of a treatment may vary as a result of several factors. Customised radiobiological evaluation is a useful adjunct to clinical evaluation in planning equivalent treatments that satisfy all dosimetric constraints.

Characterization of ferrous-methylthymol blue-polyvinyl alcohol gel dosimeters using nuclear magnetic resonance and optical techniques

NASA Astrophysics Data System (ADS)

Rabaeh, Khalid A.; Eyadeh, Molham M.; Hailat, Tariq F.; Aldweri, Feras M.; Alheet, Samer M.; Eid, Rania M.

2018-07-01

A new composition of Ferrous sulphate-Metheylthymol blue (MTB)-Polyvinyl alcohol (PVA) dosimeter is introduced in this work and evaluated using nuclear magnetic resonance (NMR) and absorbance spectrophotometry techniques. The Fricke-MTB-PVA dosimeters were irradiated using a medical linear accelerator in a cubic water phantom. The dose response of the dosimeters was investigated using NMR in terms of spin-spin relaxation rate (R2), and ultraviolet and visible regions (UV-Vis) spectrophotometry in terms of absorbance. The dosimeter presents a linear dose response for doses up to 20 Gy with UV-Vis and 40 Gy with NMR method. The sample with 0.1 mM MTB, 5% PVA by weight showed highest dose sensitivity for both techniques. The Fricke-MTB-PVA dosimeter developed in this work has a significant advance over the Fricke-MTB-gelatin system: the NMR sensitivity was remarkably improved; the auto-oxidation rate was seven times lower, and no significant dose rate or photon energy effects were observed.

Assessment of neutron dosemeters around standard sources and nuclear fissile objects.

PubMed

Raimondi, N; Tournier, B; Groetz, J E; Piot, J; Riebler, E; Crovisier, P; Chambaudet, A; Cabanné, N

2002-01-01

In order to evaluate the neutron doses around nuclear fissile objects, a comparative study has been made on several neutron dosemeters: bubble dosemeters, etched-track detectors (CR-39) and 3He-filled proportional counters used as dose-rate meters. The measurements were made on the ambient and the personal dose equivalents H*(10) and Hp(10). Results showed that several bubble dosemeters should have been used due to a low reproducibility in the measurements. A strong correlation with the neutron energy was also found, with about a 30% underestimation of Hp(10) for neutrons from the PuBe source, and about a 9% overestimation for neutrons from the 252Cf source. Measurements of the nuclear fissile objects were made using the CR-39 and the dose-rate meters. The CR-39 led to an underestimation of 30% with respect to the neutron dose-rate meter measurements. In addition, the MCNP calculation code was used in the different configurations.

Comparison of Immunogenicity Between Inactivated and Live Attenuated Hepatitis A Vaccines Among Young Adults: A 3-Year Follow-up Study.

PubMed

Liu, Xue-en; Chen, Hai-ying; Liao, Zheng; Zhou, Yisheng; Wen, Hairong; Peng, Shihui; Liu, Yan; Li, Rui; Li, Jie; Zhuang, Hui

2015-10-15

A randomized clinical trial of hepatitis A vaccines (1 or 2 doses of inactivated vaccine [Healive] or 1 dose of live attenuated vaccine [Biovac]) was conducted among adults to evaluate seroprotection rates and geometric mean concentrations of antibody against hepatitis A virus for 36 months. High rates of seroprotection persisted for at least 36 months among adults who received 1 or 2 doses of inactivated hepatitis A vaccine but not among adults who received 1 dose of live attenuated hepatitis A vaccine. The long-term serial monitoring of immunogenicity induced by 1 dose of inactivated hepatitis A vaccine is needed to determine an effective alternative to a 2-dose schedule. NCT01865968. © The Author 2015. Published by Oxford University Press on behalf of the Infectious Diseases Society of America. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Establishment of quality assurance for respiratory-gated radiotherapy using a respiration-simulating phantom and gamma index: Evaluation of accuracy taking into account tumor motion and respiratory cycle

NASA Astrophysics Data System (ADS)

Lee, Jae-Seung; Im, In-Chul; Kang, Su-Man; Goo, Eun-Hoe; Baek, Seong-Min

2013-11-01

The purpose of this study is to present a new method of quality assurance (QA) in order to ensure effective evaluation of the accuracy of respiratory-gated radiotherapy (RGR). This would help in quantitatively analyzing the patient's respiratory cycle and respiration-induced tumor motion and in performing a subsequent comparative analysis of dose distributions, using the gamma-index method, as reproduced in our in-house developed respiration-simulating phantom. Therefore, we designed a respiration-simulating phantom capable of reproducing the patient's respiratory cycle and respiration-induced tumor motion and evaluated the accuracy of RGR by estimating its pass rates. We applied the gamma index passing criteria of accepted error ranges of 3% and 3 mm for the dose distribution calculated by using the treatment planning system (TPS) and the actual dose distribution of RGR. The pass rate clearly increased inversely to the gating width chosen. When respiration-induced tumor motion was 12 mm or less, pass rates of 85% and above were achieved for the 30-70% respiratory phase, and pass rates of 90% and above were achieved for the 40-60% respiratory phase. However, a respiratory cycle with a very small fluctuation range of pass rates failed to prove reliable in evaluating the accuracy of RGR. Therefore, accurate and reliable outcomes of radiotherapy will be obtainable only by establishing a novel QA system using the respiration-simulating phantom, the gamma-index analysis, and a quantitative analysis of diaphragmatic motion, enabling an indirect measurement of tumor motion.

Comparative evaluation of two-dimensional radiography and three dimensional computed tomography based dose-volume parameters for high-dose-rate intracavitary brachytherapy of cervical cancer: a prospective study.

PubMed

Madan, Renu; Pathy, Sushmita; Subramani, Vellaiyan; Sharma, Seema; Mohanti, Bidhu Kalyan; Chander, Subhash; Thulkar, Sanjay; Kumar, Lalit; Dadhwal, Vatsla

2014-01-01

Dosimetric comparison of two dimensional (2D) radiography and three-dimensional computed tomography (3D-CT) based dose distributions with high-dose-rate (HDR) intracavitry radiotherapy (ICRT) for carcinoma cervix, in terms of target coverage and doses to bladder and rectum. Sixty four sessions of HDR ICRT were performed in 22 patients. External beam radiotherapy to pelvis at a dose of 50 Gray in 27 fractions followed by HDR ICRT, 21 Grays to point A in 3 sessions, one week apart was planned . All patients underwent 2D-orthogonal and 3D-CT simulation for each session. Treatment plans were generated using 2D-orthogonal images and dose prescription was made at point A. 3D plans were generated using 3D-CT images after delineating target volume and organs at risk. Comparative evaluation of 2D and 3D treatment planning was made for each session in terms of target coverage (dose received by 90%, 95% and 100% of the target volume: D90, D95 and D100 respectively) and doses to bladder and rectum: ICRU-38 bladder and rectum point dose in 2D planning and dose to 0.1cc, 1cc, 2cc, 5cc, and 10cc of bladder and rectum in 3D planning. Mean doses received by 100% and 90% of the target volume were 4.24 ± 0.63 and 4.9 ± 0.56 Gy respectively. Doses received by 0.1cc, 1cc and 2cc volume of bladder were 2.88 ± 0.72, 2.5 ± 0.65 and 2.2 ± 0.57 times more than the ICRU bladder reference point. Similarly, doses received by 0.1cc, 1cc and 2cc of rectum were 1.80 ± 0.5, 1.48 ± 0.41 and 1.35 ± 0.37 times higher than ICRU rectal reference point. Dosimetric comparative evaluation of 2D and 3D CT based treatment planning for the same brachytherapy session demonstrates underestimation of OAR doses and overestimation of target coverage in 2D treatment planning.

Effects of Epoetin Alfa Titration Practices, Implemented After Changes to Product Labeling, on Hemoglobin Levels, Transfusion Use, and Hospitalization Rates.

PubMed

Molony, Julia T; Monda, Keri L; Li, Suying; Beaubrun, Anne C; Gilbertson, David T; Bradbury, Brian D; Collins, Allan J

2016-08-01

Little is known about epoetin alfa (EPO) dosing at dialysis centers after implementation of the US Medicare prospective payment system and revision of the EPO label in 2011. Retrospective cohort study. Approximately 412,000 adult hemodialysis patients with Medicare Parts A and B as primary payer in 2009 to 2012 to describe EPO dosing and hemoglobin patterns; of these, about 70,000 patients clustered in about 1,300 dialysis facilities to evaluate facility-level EPO titration practices and patient-level outcomes in 2012. Facility EPO titration practices when hemoglobin levels were <10 and >11g/dL (grouped treatment variable) determined from monthly EPO dosing and hemoglobin level patterns. Patient mean hemoglobin levels, red blood cell transfusion rates, and all-cause and cause-specific hospitalization rates using a facility-based analysis. Monthly EPO dose and hemoglobin level, red blood cell transfusion rates, and all-cause and cause-specific hospitalization rates. Monthly EPO doses declined across all hemoglobin levels, with the greatest decline in patients with hemoglobin levels < 10g/dL (July-October 2011). In 2012, nine distinct facility titration practices were identified. Across groups, mean hemoglobin levels differed slightly (10.5-10.8g/dL) but within-patient hemoglobin standard deviations were similar (∼0.68g/dL). Patients at facilities implementing greater dose reductions and smaller dose escalations had lower hemoglobin levels and higher transfusion rates. In contrast, patients at facilities that implemented greater dose escalations (and large or small dose reductions) had higher hemoglobin levels and lower transfusion rates. There were no clinically meaningful differences in all-cause or cause-specific hospitalization events across groups. Possibly incomplete claims data; excluded small facilities and those without consistent titration patterns; hemoglobin levels reported monthly; inferred facility practice from observed dosing. Following prospective payment system implementation and labeling revisions, EPO doses declined significantly. Under the new label, facility EPO titration practices were associated with mean hemoglobin levels (but not standard deviations) and transfusion use, but not hospitalization rates. Copyright © 2016 National Kidney Foundation, Inc. Published by Elsevier Inc. All rights reserved.

Beta- and gamma-dose measurements of the Godiva IV critical assembly.

PubMed

Hankins, D E

1984-03-01

To aid in the re-evaluation of an exposure that occurred in 1963, information was required on the response of film badges to the beta- and gamma-ray doses from a critical assembly. Of particular interest was the beta spectra from the assembly. The techniques used and the results obtained in this study are of interest to health physicists at facilities where exposures to betas occur. The dose rates from the Los Alamos National Laboratory Godiva IV Critical Assembly were measured at numerous distances from the assembly four and 12 days following a burst. Information was obtained on the beta-particle spectra using absorption curve studies. The beta/gamma dose-rate ratio as a function of distance from the assembly was determined. Shielding provided by various metals, gloves and clothing was measured. The beta- and gamma-ray doses measured were compared with a film packet used in the past at the Nevada Test Site with two types of current TLD personnel badges. Measurements made with a commercial thin-window ion chamber instrument are compared with the dose rates obtained using other dosimeters.

Terrestrial gamma radiation dose (TGRD) levels in northern zone of Jos Plateau, Nigeria: Statistical relationship between dose rates and geological formations

NASA Astrophysics Data System (ADS)

Abba, Habu Tela; Hassan, Wan Muhamad Saridan Wan; Saleh, Muneer Aziz; Aliyu, Abubakar Sadiq; Ramli, Ahmad Termizi

2017-11-01

In- situ measurement of terrestrial gamma radiation dose rates (TGRD) was conducted in northern zone of Jos Plateau and a statistical relationship between the TGRD and the underlying geological formations was investigated. The TGRD rates in all the measurements ranged from 40 to 1265 nGy h-1 with a mean value of 250 nGy h-1. The maximum TGDR was recorded on geological type G8 (Younger Granites) at Bisitchi, and the lowest TGDR was recorded on G6 (Basaltic rocks) at Gabia. One way analysis of variance (ANOVA) statistical test was used to compared the data. Significantly, the results of this study inferred a strong relationship between TGRD levels with geological structures of a place. An isodose map was plotted to represent exposure rates due to TGRD. The results of this investigation could be useful for multiple public interest such as evaluating public dose for the area.

Lifetime Effective Dose Assessment Based on Background Outdoor Gamma Exposure in Chihuahua City, Mexico

PubMed Central

Luevano-Gurrola, Sergio; Perez-Tapia, Angelica; Pinedo-Alvarez, Carmelo; Carrillo-Flores, Jorge; Montero-Cabrera, Maria Elena; Renteria-Villalobos, Marusia

2015-01-01

Determining ionizing radiation in a geographic area serves to assess its effects on a population’s health. The aim of this study was to evaluate the spatial distribution of the background environmental outdoor gamma dose rates in Chihuahua City. This study also estimated the annual effective dose and the lifetime cancer risks of the population of this city. To determine the outdoor gamma dose rate in air, the annual effective dose and the lifetime cancer risk, 48 sampling points were randomly selected in Chihuahua City. Outdoor gamma dose rate measurements were carried out by using a Geiger-Müller counter. Outdoor gamma dose rates ranged from 113 to 310 nGy·h−1. At the same sites, 48 soil samples were taken to obtain the activity concentrations of 226Ra, 232Th and 40K and to calculate their terrestrial gamma dose rates. Radioisotope activity concentrations were determined by gamma spectrometry. Calculated gamma dose rates ranged from 56 to 193 nGy·h−1. Results indicated that the lifetime effective dose of the inhabitants of Chihuahua City is on average 19.8 mSv, resulting in a lifetime cancer risk of 0.001. In addition, the mean of the activity concentrations in soil were 52, 73 and 1097 Bq·kg−1, for 226Ra, 232Th and 40K, respectively. From the analysis, the spatial distribution of 232Th, 226Ra and 40K is to the north, to the north-center and to the south of city, respectively. In conclusion, the natural background gamma dose received by the inhabitants of Chihuahua City is high and mainly due to the geological characteristics of the zone. From the radiological point of view, this kind of study allows us to identify the importance of manmade environments, which are often highly variable and difficult to characterize. PMID:26437425

Lifetime Effective Dose Assessment Based on Background Outdoor Gamma Exposure in Chihuahua City, Mexico.

PubMed

Luevano-Gurrola, Sergio; Perez-Tapia, Angelica; Pinedo-Alvarez, Carmelo; Carrillo-Flores, Jorge; Montero-Cabrera, Maria Elena; Renteria-Villalobos, Marusia

2015-09-30

Determining ionizing radiation in a geographic area serves to assess its effects on a population's health. The aim of this study was to evaluate the spatial distribution of the background environmental outdoor gamma dose rates in Chihuahua City. This study also estimated the annual effective dose and the lifetime cancer risks of the population of this city. To determine the outdoor gamma dose rate in air, the annual effective dose and the lifetime cancer risk, 48 sampling points were randomly selected in Chihuahua City. Outdoor gamma dose rate measurements were carried out by using a Geiger-Müller counter. Outdoor gamma dose rates ranged from 113 to 310 nGy·h(-1). At the same sites, 48 soil samples were taken to obtain the activity concentrations of (226)Ra, (232)Th and (40)K and to calculate their terrestrial gamma dose rates. Radioisotope activity concentrations were determined by gamma spectrometry. Calculated gamma dose rates ranged from 56 to 193 nGy·h(-1). Results indicated that the lifetime effective dose of the inhabitants of Chihuahua City is on average 19.8 mSv, resulting in a lifetime cancer risk of 0.001. In addition, the mean of the activity concentrations in soil were 52, 73 and 1097 Bq·kg(-1), for (226)Ra, (232)Th and (40)K, respectively. From the analysis, the spatial distribution of (232)Th, (226)Ra and (40)K is to the north, to the north-center and to the south of city, respectively. In conclusion, the natural background gamma dose received by the inhabitants of Chihuahua City is high and mainly due to the geological characteristics of the zone. From the radiological point of view, this kind of study allows us to identify the importance of manmade environments, which are often highly variable and difficult to characterize.

Evaluation of the effect of prostate volume change on tumor control probability in LDR brachytherapy.

PubMed

Knaup, Courtney; Mavroidis, Panayiotis; Stathakis, Sotirios; Smith, Mark; Swanson, Gregory; Papanikolaou, Niko

2011-09-01

This study evaluates low dose-rate brachytherapy (LDR) prostate plans to determine the biological effect of dose degradation due to prostate volume changes. In this study, 39 patients were evaluated. Pre-implant prostate volume was determined using ultrasound. These images were used with the treatment planning system (Nucletron Spot Pro 3.1(®)) to create treatment plans using (103)Pd seeds. Following the implant, patients were imaged using CT for post-implant dosimetry. From the pre and post-implant DVHs, the biologically equivalent dose and the tumor control probability (TCP) were determined using the biologically effective uniform dose. The model used RBE = 1.75 and α/β = 2 Gy. The prostate volume changed between pre and post implant image sets ranged from -8% to 110%. TCP and the mean dose were reduced up to 21% and 56%, respectively. TCP is observed to decrease as the mean dose decreases to the prostate. The post-implant tumor dose was generally observed to decrease, compared to the planned dose. A critical uniform dose of 130 Gy was established. Below this dose, TCP begins to fall-off. It was also determined that patients with a small prostates were more likely to suffer TCP decrease. The biological effect of post operative prostate growth due to operative trauma in LDR was evaluated using the concept. The post-implant dose was lower than the planned dose due to an increase of prostate volume post-implant. A critical uniform dose of 130 Gy was determined, below which TCP begun to decline.

HLW Flexible jumper materials compatibility evaluation

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

Skidmore, T. E.

H-Tank Farm Engineering tasked SRNL/Materials Science & Technology (MS&T) to evaluate the compatibility of Goodyear Viper® chemical transfer hose with HLW solutions. The hose is proposed as a flexible Safety Class jumper for up to six months service. SRNL/MS&T performed various tests to evaluate the effects of radiation, high pH chemistry and elevated temperature on the hose, particularly the inner liner. Test results suggest an upper dose limit of 50 Mrad for the hose. Room temperature burst pressure values at 50 Mrad are estimated at 600- 800 psi, providing a safety factor of 4.0-5.3X over the anticipated operating pressure ofmore » 150 psi and a safety factor of 3.0-4.0X over the working pressure of the hose (200 psi), independent of temperature effects. Radiation effects are minimal at doses less than 10 Mrad. Doses greater than 50 Mrad may be allowed, depending on operating conditions and required safety factors, but cannot be recommended at this time. At 250 Mrad, burst pressure values are reduced to the hose working pressure. At 300 Mrad, burst pressures are below 150 psi. At a bounding continuous dose rate of 57,870 rad/hr, the 50 Mrad dose limit is reached within 1.2 months. Actual dose rates may be lower, particularly during non-transfer periods. Refined dose calculations are therefore recommended to justify longer service. This report details the tests performed and interpretation of the results. Recommendations for shelf-life/storage, component quality verification, and post-service examination are provided.« less

Initial clinical results with a new needle screen storage phosphor system in chest radiograms.

PubMed

Körner, M; Wirth, S; Treitl, M; Reiser, M; Pfeifer, K-J

2005-11-01

To evaluate image quality and anatomical detail depiction in dose-reduced digital plain chest radiograms using a new needle screen storage phosphor (NIP) in comparison to full dose conventional powder screen storage phosphor (PIP) images. 24 supine chest radiograms were obtained with PIP at standard dose and compared to follow-up studies of the same patients obtained with NIP with dose reduced to 50 % of the PIP dose (all imaging systems: AGFA-Gevaert, Mortsel, Belgium). In both systems identical versions of post-processing software supplied by the manufacturer were used with matched parameters. Six independent readers blinded to both modality and dose evaluated the images for depiction and differentiation of defined anatomical regions (peripheral lung parenchyma, central lung parenchyma, hilum, heart, diaphragm, upper mediastinum, and bone). All NIP images were compared to the corresponding PIP images using a five-point scale (- 2, clearly inferior to + 2, clearly superior). Overall image quality was rated for each PIP and NIP image separately (1, not usable to 5, excellent). PIP and dose reduced NIP images were rated equivalent. Mean image noise impression was only slightly higher on NIP images. Mean image quality for NIP showed no significant differences (p > 0.05, Mann-Whitney U test). With the use of the new needle structured storage phosphors in chest radiography, dose reduction of up to 50 % is possible without detracting from image quality or detail depiction. Especially in patients with multiple follow-up studies the overall dose can be decreased significantly.

Assessing doses to terrestrial wildlife at a radioactive waste disposal site: inter-comparison of modelling approaches.

PubMed

Johansen, M P; Barnett, C L; Beresford, N A; Brown, J E; Černe, M; Howard, B J; Kamboj, S; Keum, D-K; Smodiš, B; Twining, J R; Vandenhove, H; Vives i Batlle, J; Wood, M D; Yu, C

2012-06-15

Radiological doses to terrestrial wildlife were examined in this model inter-comparison study that emphasised factors causing variability in dose estimation. The study participants used varying modelling approaches and information sources to estimate dose rates and tissue concentrations for a range of biota types exposed to soil contamination at a shallow radionuclide waste burial site in Australia. Results indicated that the dominant factor causing variation in dose rate estimates (up to three orders of magnitude on mean total dose rates) was the soil-to-organism transfer of radionuclides that included variation in transfer parameter values as well as transfer calculation methods. Additional variation was associated with other modelling factors including: how participants conceptualised and modelled the exposure configurations (two orders of magnitude); which progeny to include with the parent radionuclide (typically less than one order of magnitude); and dose calculation parameters, including radiation weighting factors and dose conversion coefficients (typically less than one order of magnitude). Probabilistic approaches to model parameterisation were used to encompass and describe variable model parameters and outcomes. The study confirms the need for continued evaluation of the underlying mechanisms governing soil-to-organism transfer of radionuclides to improve estimation of dose rates to terrestrial wildlife. The exposure pathways and configurations available in most current codes are limited when considering instances where organisms access subsurface contamination through rooting, burrowing, or using different localised waste areas as part of their habitual routines. Crown Copyright © 2012. Published by Elsevier B.V. All rights reserved.

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

PubMed Central

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

2012-01-01

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

Model-based Iterative Reconstruction: Effect on Patient Radiation Dose and Image Quality in Pediatric Body CT

PubMed Central

Dillman, Jonathan R.; Goodsitt, Mitchell M.; Christodoulou, Emmanuel G.; Keshavarzi, Nahid; Strouse, Peter J.

2014-01-01

Purpose To retrospectively compare image quality and radiation dose between a reduced-dose computed tomographic (CT) protocol that uses model-based iterative reconstruction (MBIR) and a standard-dose CT protocol that uses 30% adaptive statistical iterative reconstruction (ASIR) with filtered back projection. Materials and Methods Institutional review board approval was obtained. Clinical CT images of the chest, abdomen, and pelvis obtained with a reduced-dose protocol were identified. Images were reconstructed with two algorithms: MBIR and 100% ASIR. All subjects had undergone standard-dose CT within the prior year, and the images were reconstructed with 30% ASIR. Reduced- and standard-dose images were evaluated objectively and subjectively. Reduced-dose images were evaluated for lesion detectability. Spatial resolution was assessed in a phantom. Radiation dose was estimated by using volumetric CT dose index (CTDIvol) and calculated size-specific dose estimates (SSDE). A combination of descriptive statistics, analysis of variance, and t tests was used for statistical analysis. Results In the 25 patients who underwent the reduced-dose protocol, mean decrease in CTDIvol was 46% (range, 19%–65%) and mean decrease in SSDE was 44% (range, 19%–64%). Reduced-dose MBIR images had less noise (P > .004). Spatial resolution was superior for reduced-dose MBIR images. Reduced-dose MBIR images were equivalent to standard-dose images for lungs and soft tissues (P > .05) but were inferior for bones (P = .004). Reduced-dose 100% ASIR images were inferior for soft tissues (P < .002), lungs (P < .001), and bones (P < .001). By using the same reduced-dose acquisition, lesion detectability was better (38% [32 of 84 rated lesions]) or the same (62% [52 of 84 rated lesions]) with MBIR as compared with 100% ASIR. Conclusion CT performed with a reduced-dose protocol and MBIR is feasible in the pediatric population, and it maintains diagnostic quality. © RSNA, 2013 Online supplemental material is available for this article. PMID:24091359

Evaluation of Gamma Radiation-Induced Biochemical Changes in Skin for Dose Assesment: A Study on Small Experimental Animals.

PubMed

Kumar Soni, Sandeep; Basu, Mitra; Agrawal, Priyanka; Bhatnagar, Aseem; Chhillar, Neelam

2018-05-24

Researchers have been evaluating several approaches to assess acute radiation injury/toxicity markers owing to radiation exposure. Keeping in mind this background, we assumed that whole-body irradiation in single fraction in graded doses can affect the antioxidant profile in skin that could be used as an acute radiation injury/toxicity marker. Sprague-Dawley rats were treated with CO-60 gamma radiation (dose: 1-5 Gy; dose rate: 0.85 Gy/minute). Skin samples were collected (before and after radiation up to 72 hours) and analyzed for glutathione (GSH), glutathione peroxidase (GPx), superoxide dismutase (SOD), catalase (CAT), and lipid peroxidation (LPx). Intra-group comparison showed significant differences in GSH, GPx, SOD, and CAT, and they declined in a dose-dependent manner from 1 to 5 Gy (P value0.05). This study suggests that skin antioxidants were sensitive toward radiation even at a low radiation dose, which can be used as a predictor of radiation injury and altered in a dose-dependent manner. These biochemical parameters may have wider application in the evaluation of radiation-induced skin injury and dose assessment. (Disaster Med Public Health Preparedness. 2018;page 1 of 6).

Simplification of an MCNP model designed for dose rate estimation

NASA Astrophysics Data System (ADS)

Laptev, Alexander; Perry, Robert

2017-09-01

A study was made to investigate the methods of building a simplified MCNP model for radiological dose estimation. The research was done using an example of a complicated glovebox with extra shielding. The paper presents several different calculations for neutron and photon dose evaluations where glovebox elements were consecutively excluded from the MCNP model. The analysis indicated that to obtain a fast and reasonable estimation of dose, the model should be realistic in details that are close to the tally. Other details may be omitted.

Development of a synthetic single crystal diamond dosimeter for dose measurement of clinical proton beams

NASA Astrophysics Data System (ADS)

Moignier, Cyril; Tromson, Dominique; de Marzi, Ludovic; Marsolat, Fanny; García Hernández, Juan Carlos; Agelou, Mathieu; Pomorski, Michal; Woo, Romuald; Bourbotte, Jean-Michel; Moignau, Fabien; Lazaro, Delphine; Mazal, Alejandro

2017-07-01

The scope of this work was to develop a synthetic single crystal diamond dosimeter (SCDD-Pro) for accurate relative dose measurements of clinical proton beams in water. Monte Carlo simulations were carried out based on the MCNPX code in order to investigate and reduce the dose curve perturbation caused by the SCDD-Pro. In particular, various diamond thicknesses were simulated to evaluate the influence of the active volume thickness (e AV) as well as the influence of the addition of a front silver resin (250 µm in thickness in front of the diamond crystal) on depth-dose curves. The simulations indicated that the diamond crystal alone, with a small e AV of just 5 µm, already affects the dose at Bragg peak position (Bragg peak dose) by more than 2% with respect to the Bragg peak dose deposited in water. The optimal design that resulted from the Monte Carlo simulations consists of a diamond crystal of 1 mm in width and 150 µm in thickness with the front silver resin, enclosed by a water-equivalent packaging. This design leads to a deviation between the Bragg peak dose from the full detector modeling and the Bragg peak dose deposited in water of less than 1.2%. Based on those optimizations, an SCDD-Pro prototype was built and evaluated in broad passive scattering proton beams. The experimental evaluation led to probed SCDD-Pro repeatability, dose rate dependence and linearity, that were better than 0.2%, 0.4% (in the 1.0-5.5 Gy min-1 range) and 0.4% (for dose higher than 0.05 Gy), respectively. The depth-dose curves in the 90-160 MeV energy range, measured with the SCDD-Pro without applying any correction, were in good agreement with those measured using a commercial IBA PPC05 plane-parallel ionization chamber, differing by less than 1.6%. The experimental results confirmed that this SCDD-Pro is suitable for measurements with standard electrometers and that the depth-dose curve perturbation is negligible, with no energy dependence and no significant dose rate dependence.

Development of a synthetic single crystal diamond dosimeter for dose measurement of clinical proton beams.

PubMed

Moignier, Cyril; Tromson, Dominique; de Marzi, Ludovic; Marsolat, Fanny; García Hernández, Juan Carlos; Agelou, Mathieu; Pomorski, Michal; Woo, Romuald; Bourbotte, Jean-Michel; Moignau, Fabien; Lazaro, Delphine; Mazal, Alejandro

2017-07-07

The scope of this work was to develop a synthetic single crystal diamond dosimeter (SCDD-Pro) for accurate relative dose measurements of clinical proton beams in water. Monte Carlo simulations were carried out based on the MCNPX code in order to investigate and reduce the dose curve perturbation caused by the SCDD-Pro. In particular, various diamond thicknesses were simulated to evaluate the influence of the active volume thickness (e AV ) as well as the influence of the addition of a front silver resin (250 µm in thickness in front of the diamond crystal) on depth-dose curves. The simulations indicated that the diamond crystal alone, with a small e AV of just 5 µm, already affects the dose at Bragg peak position (Bragg peak dose) by more than 2% with respect to the Bragg peak dose deposited in water. The optimal design that resulted from the Monte Carlo simulations consists of a diamond crystal of 1 mm in width and 150 µm in thickness with the front silver resin, enclosed by a water-equivalent packaging. This design leads to a deviation between the Bragg peak dose from the full detector modeling and the Bragg peak dose deposited in water of less than 1.2%. Based on those optimizations, an SCDD-Pro prototype was built and evaluated in broad passive scattering proton beams. The experimental evaluation led to probed SCDD-Pro repeatability, dose rate dependence and linearity, that were better than 0.2%, 0.4% (in the 1.0-5.5 Gy min -1 range) and 0.4% (for dose higher than 0.05 Gy), respectively. The depth-dose curves in the 90-160 MeV energy range, measured with the SCDD-Pro without applying any correction, were in good agreement with those measured using a commercial IBA PPC05 plane-parallel ionization chamber, differing by less than 1.6%. The experimental results confirmed that this SCDD-Pro is suitable for measurements with standard electrometers and that the depth-dose curve perturbation is negligible, with no energy dependence and no significant dose rate dependence.

Dose properties of a laser accelerated electron beam and prospects for clinical application.

PubMed

Kainz, K K; Hogstrom, K R; Antolak, J A; Almond, P R; Bloch, C D; Chiu, C; Fomytskyi, M; Raischel, F; Downer, M; Tajima, T

2004-07-01

Laser wakefield acceleration (LWFA) technology has evolved to where it should be evaluated for its potential as a future competitor to existing technology that produces electron and x-ray beams. The purpose of the present work is to investigate the dosimetric properties of an electron beam that should be achievable using existing LWFA technology, and to document the necessary improvements to make radiotherapy application for LWFA viable. This paper first qualitatively reviews the fundamental principles of LWFA and describes a potential design for a 30 cm accelerator chamber containing a gas target. Electron beam energy spectra, upon which our dose calculations are based, were obtained from a uniform energy distribution and from two-dimensional particle-in-cell (2D PIC) simulations. The 2D PIC simulation parameters are consistent with those reported by a previous LWFA experiment. According to the 2D PIC simulations, only approximately 0.3% of the LWFA electrons are emitted with an energy greater than 1 MeV. We studied only the high-energy electrons to determine their potential for clinical electron beams of central energy from 9 to 21 MeV. Each electron beam was broadened and flattened by designing a dual scattering foil system to produce a uniform beam (103%>off-axis ratio>95%) over a 25 x 25 cm2 field. An energy window (deltaE) ranging from 0.5 to 6.5 MeV was selected to study central-axis depth dose, beam flatness, and dose rate. Dose was calculated in water at a 100 cm source-to-surface distance using the EGS/BEAM Monte Carlo algorithm. Calculations showed that the beam flatness was fairly insensitive to deltaE. However, since the falloff of the depth-dose curve (R10-R90) and the dose rate both increase with deltaE, a tradeoff between minimizing (R10-R90) and maximizing dose rate is implied. If deltaE is constrained so that R10-R90 is within 0.5 cm of its value for a monoenergetic beam, the maximum practical dose rate based on 2D PIC is approximately 0.1 Gy min(-1) for a 9 MeV beam and 0.03 Gy min(-1) for a 15 MeV beam. It was concluded that current LWFA technology should allow a table-top terawatt (T3) laser to produce therapeutic electron beams that have acceptable flatness, penetration, and falloff of depth dose; however, the dose rate is still 1%-3% of that which would be acceptable, especially for higher-energy electron beams. Further progress in laser technology, e.g., increasing the pulse repetition rate or number of high energy electrons generated per pulse, is necessary to give dose rates acceptable for electron beams. Future measurements confirming dosimetric calculations are required to substantiate our results. In addition to achieving adequate dose rate, significant engineering developments are needed for this technology to compete with current electron acceleration technology. Also, the functional benefits of LWFA electron beams require further study and evaluation.

Dose Calculations for [131I] Meta-Iodobenzylguanidine-Induced Bystander Effects

PubMed Central

Gow, M. D.; Seymour, C. B.; Boyd, M.; Mairs, R. J.; Prestiwch, W. V.; Mothersill, C. E.

2014-01-01

Targeted radiotherapy is a potentially useful treatment for some cancers and may be potentiated by bystander effects. However, without estimation of absorbed dose, it is difficult to compare the effects with conventional external radiation treatment. Methods: Using the Vynckier – Wambersie dose point kernel, a model for dose rate evaluation was created allowing for calculation of absorbed dose values to two cell lines transfected with the noradrenaline transporter (NAT) gene and treated with [131I]MIBG. Results: The mean doses required to decrease surviving fractions of UVW/NAT and EJ138/NAT cells, which received medium from [131I]MIBG-treated cells, to 25 – 30% were 1.6 and 1.7 Gy respectively. The maximum mean dose rates achieved during [131I]MIBG treatment were 0.09 – 0.75 Gy/h for UVW/NAT and 0.07 – 0.78 Gy/h for EJ138/NAT. These were significantly lower than the external beam gamma radiation dose rate of 15 Gy/h. In the case of control lines which were incapable of [131I]MIBG uptake the mean absorbed doses following radiopharmaceutical were 0.03 – 0.23 Gy for UVW and 0.03 – 0.32 Gy for EJ138. Conclusion: [131I]MIBG treatment for ICCM production elicited a bystander dose-response profile similar to that generated by external beam gamma irradiation but with significantly greater cell death. PMID:24659931

Staff Radiation Doses in a Real-Time Display Inside the Angiography Room

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

Sanchez, Roberto, E-mail: rmsanchez.hcsc@salud.madrid.org; Vano, E.; Fernandez, J. M.

MethodsThe evaluation of a new occupational Dose Aware System (DAS) showing staff radiation doses in real time has been carried out in several angiography rooms in our hospital. The system uses electronic solid-state detectors with high-capacity memory storage. Every second, it archives the dose and dose rate measured and is wirelessly linked to a base-station screen mounted close to the diagnostic monitors. An easy transfer of the values to a data sheet permits further analysis of the scatter dose profile measured during the procedure, compares it with patient doses, and seeks to find the most effective actions to reduce operatormore » exposure to radiation.ResultsThe cumulative occupational doses measured per procedure (shoulder-over lead apron) ranged from 0.6 to 350 {mu}Sv when the ceiling-suspended screen was used, and DSA (Digital Subtraction Acquisition) runs were acquired while the personnel left the angiography room. When the suspended screen was not used and radiologists remained inside the angiography room during DSA acquisitions, the dose rates registered at the operator's position reached up to 1-5 mSv/h during fluoroscopy and 12-235 mSv/h during DSA acquisitions. In such case, the cumulative scatter dose could be more than 3 mSv per procedure.ConclusionReal-time display of doses to staff members warns interventionists whenever the scatter dose rates are too high or the radiation protection tools are not being properly used, providing an opportunity to improve personal protection accordingly.« less

Six steps to a successful dose-reduction strategy

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

Bennett, M.

1995-03-01

The increased importance of demonstrating achievement of the ALARA principle has helped produce a proliferation of dose-reduction ideas. Across a company there may be many dose-reduction items being pursued in a variety of areas. However, companies have a limited amount of resource and, therefore, to ensure funding is directed to those items which will produce the most benefit and that all areas apply a common policy, requires the presence of a dose-reduction strategy. Six steps were identified in formulating the dose-reduction strategy for Rolls-Royce and Associates (RRA): (1) collating the ideas; (2) quantitatively evaluating them on a common basis; (3)more » prioritizing the ideas in terms of cost benefit, (4) implementation of the highest priority items; (5) monitoring their success; (6) periodically reviewing the strategy. Inherent in producing the dose-reduction strategy has been a comprehensive dose database and the RRA-developed dose management computer code DOMAIN, which allows prediction of dose rates and dose. The database enabled high task dose items to be identified, assisted in evaluating dose benefits, and monitored dose trends once items had been implemented. The DOMAIN code was used both in quantifying some of the project dose benefits and its results, such as dose contours, used in some of the dose-reduction items themselves. In all, over fifty dose-reduction items were evaluated in the strategy process and the items which will give greatest benefit are being implemented. The strategy has been successful in giving renewed impetus and direction to dose-reduction management.« less

Absorbed dose calculations in a brachytherapy pelvic phantom using the Monte Carlo method

PubMed Central

Rodríguez, Miguel L.; deAlmeida, Carlos E.

2002-01-01

Monte Carlo calculations of the absorbed dose at various points of a brachytherapy anthropomorphic phantom are presented. The phantom walls and internal structures are made of polymethylmethacrylate and its external shape was taken from a female Alderson phantom. A complete Fletcher‐Green type applicator with the uterine tandem was fixed at the bottom of the phantom reproducing a typical geometrical configuration as that attained in a gynecological brachytherapy treatment. The dose rate produced by an array of five 137Cs CDC‐J type sources placed in the applicator colpostats and the uterine tandem was evaluated by Monte Carlo simulations using the code penelope at three points: point A, the rectum, and the bladder. The influence of the applicator in the dose rate was evaluated by comparing Monte Carlo simulations of the sources alone and the sources inserted in the applicator. Differences up to 56% in the dose may be observed for the two cases in the planes including the rectum and bladder. The results show a reduction of the dose of 15.6%, 14.0%, and 5.6% in the rectum, bladder, and point A respectively, when the applicator wall and shieldings are considered. PACS number(s): 87.53Jw, 87.53.Wz, 87.53.Vb, 87.66.Xa PMID:12383048

Evaluation of Gafchromic EBT-XD film, with comparison to EBT3 film, and application in high dose radiotherapy verification.

PubMed

Palmer, Antony L; Dimitriadis, Alexis; Nisbet, Andrew; Clark, Catharine H

2015-11-21

There is renewed interest in film dosimetry for the verification of dose delivery of complex treatments, particularly small fields, compared to treatment planning system calculations. A new radiochromic film, Gafchromic EBT-XD, is available for high-dose treatment verification and we present the first published evaluation of its use. We evaluate the new film for MV photon dosimetry, including calibration curves, performance with single- and triple-channel dosimetry, and comparison to existing EBT3 film. In the verification of a typical 25 Gy stereotactic radiotherapy (SRS) treatment, compared to TPS planned dose distribution, excellent agreement was seen with EBT-XD using triple-channel dosimetry, in isodose overlay, maximum 1.0 mm difference over 200-2400 cGy, and gamma evaluation, mean passing rate 97% at 3% locally-normalised, 1.5 mm criteria. In comparison to EBT3, EBT-XD gave improved evaluation results for the SRS-plan, had improved calibration curve gradients at high doses, and had reduced lateral scanner effect. The dimensions of the two films are identical. The optical density of EBT-XD is lower than EBT3 for the same dose. The effective atomic number for both may be considered water-equivalent in MV radiotherapy. We have validated the use of EBT-XD for high-dose, small-field radiotherapy, for routine QC and a forthcoming multi-centre SRS dosimetry intercomparison.

Evaluation of Gafchromic EBT-XD film, with comparison to EBT3 film, and application in high dose radiotherapy verification

NASA Astrophysics Data System (ADS)

Palmer, Antony L.; Dimitriadis, Alexis; Nisbet, Andrew; Clark, Catharine H.

2015-11-01

There is renewed interest in film dosimetry for the verification of dose delivery of complex treatments, particularly small fields, compared to treatment planning system calculations. A new radiochromic film, Gafchromic EBT-XD, is available for high-dose treatment verification and we present the first published evaluation of its use. We evaluate the new film for MV photon dosimetry, including calibration curves, performance with single- and triple-channel dosimetry, and comparison to existing EBT3 film. In the verification of a typical 25 Gy stereotactic radiotherapy (SRS) treatment, compared to TPS planned dose distribution, excellent agreement was seen with EBT-XD using triple-channel dosimetry, in isodose overlay, maximum 1.0 mm difference over 200-2400 cGy, and gamma evaluation, mean passing rate 97% at 3% locally-normalised, 1.5 mm criteria. In comparison to EBT3, EBT-XD gave improved evaluation results for the SRS-plan, had improved calibration curve gradients at high doses, and had reduced lateral scanner effect. The dimensions of the two films are identical. The optical density of EBT-XD is lower than EBT3 for the same dose. The effective atomic number for both may be considered water-equivalent in MV radiotherapy. We have validated the use of EBT-XD for high-dose, small-field radiotherapy, for routine QC and a forthcoming multi-centre SRS dosimetry intercomparison.

[Application of half-dose depot long-acting triptorelin in postoperative adjuvant therapy for endometriosis].

PubMed

Liu, Xia; Zhang, Hong-xia; Wang, Li-ping; Fu, Wei-ping

2013-01-15

To evaluate the efficacy and adverse effects of half-dose depot long-acting triptorelin in the therapy of endometriosis. The efficacy and adverse effects of routine-dose or half-dose triptorelin in postoperative endometriosis patients were prospectively observed. A total of 186 postoperative patients with moderate or severe endometriosis received an intramuscular injection of triptorelin every 28 days for 6 times. They were randomly divided into 3 groups, i.e. half-dose group (n = 99): 1.875 mg each time; "draw-back" group (n = 52): 3.75 mg first time, then 1.875 mg each time; and routine-dose group (n = 35): 3.75 mg each time. Amenorrhea was effectively induced in all patients after the second injection. There was no significant difference in the rate of serum E2 level at Day 28 of every injection below the upper limit of "estrogen threshold (110 - 146 pmol/L)" not stimulating ectopic endometrium proliferation among half-dose group, "draw-back" group and routine-dose group (99% vs 100% and 99.0%, P > 0.05), the percentage of E2 < 37 pmol/L in E2 < 110 pmol/L in half-dose group was significantly lower than that in "draw-back" and routine-dose groups after 2-5(th) injection (69% vs 79% and 85%, P < 0.01), but there was no significant difference after first half-dose and routine-dose injection (71% vs 73%, P > 0.05). No significant difference existed in the rate of pelvic pain relief during the first returning menstruation and the recurrence rate of endometriosis within 1 year postoperation among three groups (both P > 0.05). However, the incidences of menopausal syndrome and severe menopausal syndrome in half-dose group were significantly lower than those in "draw-back" and routine-dose groups (both P < 0.01). And the incompletion rate of six-time drug for severe menopause syndrome was also significantly lower (P < 0.05) while the completion rate of six-time drug use in half-dose group was significantly higher (P < 0.05). As a postoperative adjuvant, half-dose depot triptorelin therapy is efficacious for endometriosis. It reduces menopausal syndrome and treatment cost and enhances patient compliance.

Effect of combined heat and radiation on microbial destruction

NASA Technical Reports Server (NTRS)

Fisher, D. A.; Pflug, I. J.

1977-01-01

A series of experiments at several levels of relative humidity and radiation dose rates was carried out using spores of Bacillus subtilis var. niger to evaluate the effect of heat alone, radiation alone, and a combination of heat and radiation. Combined heat and radiation treatment of microorganisms yields a destruction rate greater than the additive rates of the independent agents. The synergistic mechanism shows a proportional dependency on radiation dose rate, an Arrhenius dependence on temperature, and a dependency on relative humidity. Maximum synergism occurs under conditions where heat and radiation individually destroy microorganisms at approximately equal rates. Larger synergistic advantage is possible at low relative humidities rather than at high relative humidities.

Impact of weight-based ribavirin with peginterferon alfa-2b in African Americans with hepatitis C virus genotype 1.

PubMed

Jacobson, Ira M; Brown, Robert S; McCone, Jonathan; Black, Martin; Albert, Clive; Dragutsky, Michael S; Siddiqui, Firdous A; Hargrave, Thomas; Kwo, Paul Y; Lambiase, Louis; Galler, Greg W; Araya, Victor; Freilich, Bradley; Harvey, Joann; Griffel, Louis H; Brass, Clifford A

2007-10-01

WIN-R (Weight-based dosing of pegINterferon alfa-2b and Ribavirin) was a multicenter, randomized, open-label, investigator-initiated trial involving 236 community and academic sites in the United States, comparing response to pegylated interferon (PEG-IFN) alfa-2b plus a flat or weight-based dose of ribavirin (RBV) in treatment-naive patients with chronic hepatitis C and compensated liver disease. Patients were randomized to receive PEG-IFN alfa-2b at 1.5 microg/kg/week plus flat-dose (800 mg/day) or weight-based-dose RBV (800 mg/day for weight <65 kg, 1000 mg/day for 65-85 kg, 1200 mg/day for >85-105 kg, or 1400 mg/day for >105-<125 kg). Sustained virologic response (SVR; undetectable [<125 IU/mL] hepatitis C virus [HCV] RNA at end of follow-up) in patients > or =65 kg was the primary end point. Low SVR rates have been reported among African American individuals, in whom there is a preponderance of HCV genotype 1. This subanalysis of WIN-R was conducted to evaluate the efficacy of weight-based dosing among African American individuals with genotype 1 infection enrolled in the trial. Of 362 African American patients in the primary efficacy analysis, 188 received RBV flat dosing and 174 received weight-based dosing. SVR rates were higher (21% versus 10%; P = 0.0006) and relapse rates were lower (22% versus 30%) in the weight-based-dose group than in the flat-dose group. Safety and rates of drug discontinuation were similar between the 2 groups. Weight-based dosing of RBV is more effective than flat dosing in combination with PEG-IFN alfa-2b in African American individuals with HCV genotype 1. Even with weight-based dosing, response rates in African American individuals are lower than reported in other ethnic groups.

Spiromax, a New Dry Powder Inhaler: Dose Consistency under Simulated Real-World Conditions

PubMed Central

Canonica, Giorgio Walter; Arp, Jan; Keegstra, Johan René

2015-01-01

Abstract Background: Spiromax® is a novel dry powder inhaler for patients with asthma or chronic obstructive pulmonary disease (COPD). The studies presented here provide further data on attributes (in vitro dosing consistency with budesonide–formoterol (DuoResp) Spiromax; flow rates through empty versions of the Spiromax and Turbuhaler inhaler) of importance to patients with asthma or COPD. Methods: Dose-delivery studies were performed using low-, middle-, and high-strength DuoResp Spiromax. Dose consistency was assessed over inhaler life. Total emitted doses (TEDs) were measured at various flow rates, after exposure to high and low temperature or humidity, at different inhaler orientations, and after dropping the inhaler. The criterion for evaluating dose uniformity was whether mean TEDs were within the product specification limits. In separate studies, flow rates were measured after training, using the patient information leaflets, and again after enhanced training as part of a randomized, open-label, cross-over study. Results: Mean values for both budesonide and formoterol were within 85%–115% of the label claim for each strength of DuoResp Spiromax for initial dose uniformity and for the other investigated conditions (temperature, humidity, orientation, dropping, knocking), with the exception of approximately an 80% increase in first dose after dropping the inhaler (subsequent doses not affected). In the flow rate patient study, two patients' inhalations with Spiromax and six with Turbuhaler were <30 L/min. The majority of asthma patients [91% (Spiromax) versus 82% (Turbuhaler)] achieved the preferred flow rate of >60 L/min. Conclusions: DuoResp Spiromax consistently meets dose uniformity criteria, under controlled laboratory conditions and with variations intended to mimic real-world use. Following enhanced training, all patients in the flow study were able to achieve the minimal inspiratory flow rate of >30 L/min, which is required for effective treatment. PMID:26352860

A new metric for assessing IMRT modulation complexity and plan deliverability.

PubMed

McNiven, Andrea L; Sharpe, Michael B; Purdie, Thomas G

2010-02-01

To evaluate the utility of a new complexity metric, the modulation complexity score (MCS), in the treatment planning and quality assurance processes and to evaluate the relationship of the metric with deliverability. A multisite (breast, rectum, prostate, prostate bed, lung, and head and neck) and site-specific (lung) dosimetric evaluation has been completed. The MCS was calculated for each beam and the overall treatment plan. A 2D diode array (MapCHECK, Sun Nuclear, Melbourne, FL) was used to acquire measurements for each beam. The measured and planned dose (PINNACLE3, Phillips, Madison, WI) was evaluated using different percent differences and distance to agreement (DTA) criteria (3%/ 3 mm and 2%/ 1 mm) and the relationship between the dosimetric results and complexity (as measured by the MCS or simple beam parameters) assessed. For the multisite analysis (243 plans total), the mean MCS scores for each treatment site were breast (0.92), rectum (0.858), prostate (0.837), prostate bed (0.652), lung (0.631), and head and neck (0.356). The MCS allowed for compilation of treatment site-specific statistics, which is useful for comparing different techniques, as well as for comparison of individual treatment plans with the typical complexity levels. For the six plans selected for dosimetry, the average diode percent pass rate was 98.7% (minimum of 96%) for 3%/3 mm evaluation criteria. The average difference in absolute dose measurement between the planned and measured dose was 1.7 cGy. The detailed lung analysis also showed excellent agreement between the measured and planned dose, as all beams had a diode percentage pass rate for 3%/3 mm criteria of greater than 95.9%, with an average pass rate of 99.0%. The average absolute maximum dose difference for the lung plans was 0.7 cGy. There was no direct correlation between the MCS and simple beam parameters which could be used as a surrogate for complexity level (i.e., number of segments or MU). An evaluation criterion of 2%/ 1 mm reliably allowed for the identification of beams that are dosimetrically robust. In this study we defined a robust beam or plan as one that maintained a diode percentage pass rate greater than 90% at 2%/ 1 mm, indicating delivery that was deemed accurate when compared to the planned dose, even under stricter evaluation criterion. MCS and MU threshold criteria were determined by defining a required specificity of 1.0. A MCS threshold of 0.8 allowed for identification of robust deliverability with a sensitivity of 0.36. In contrast, MU had a lower sensitivity of 0.23 for a threshold of 50 MU. The MCS allows for a quantitative assessment of plan complexity, on a fixed scale, that can be applied to all treatment sites and can provide more information related to dose delivery than simple beam parameters. This could prove useful throughout the entire treatment planning and QA process.

Safety and immunogenicity of a monovalent MF59®-adjuvanted A/H1N1 vaccine in HIV-infected children and young adults.

PubMed

Palma, Paolo; Romiti, Maria Luisa; Bernardi, Stefania; Pontrelli, Giuseppe; Mora, Nadia; Santilli, Veronica; Tchidjou, Hyppolite Kuekou; Aquilani, Angela; Cotugno, Nicola; Alghisi, Federico; Lucidi, Vincenzina; Rossi, Paolo; Douagi, Iyadh

2012-03-01

This Phase IV study evaluated the safety and immunogenicity of a two-dose, MF59®-adjuvanted (Novartis Vaccines, Marburg, Germany), monovalent, A/H1N1 pandemic influenza vaccination schedule in Human Immunodeficiency Virus (HIV) positive children and young adults. A total of 83 children infected with HIV-1, and 37 non-immunocompromised, age-matched controls were enrolled. All participants received two vaccine doses administered three weeks apart. Antibody responses were assessed by haemagglutination assay at baseline, three weeks after each vaccine dose, and six months after immunization. Vaccines were evaluated according to European influenza vaccine licensure criteria. The investigational vaccine was well tolerated. After the first vaccine dose, seroconversion rates were significantly lower in HIV-positive patients (60%) than controls (82%), with GMTs of 419 and 600, respectively. No significant differences in seroconversion rates were observed between the two study groups in response to the second vaccine dose. Persisting antibody titers were similar for both HIV-positive and non-infected controls, six months after immunization. One dose of MF59-adjuvanted vaccine was sufficient to provide adequate levels of seroprotection against A/H1N1 influenza disease in HIV-positive children. However, a two-dose vaccination schedule may be optimal for this population. Copyright © 2011 The International Alliance for Biological Standardization. Published by Elsevier Ltd. All rights reserved.

The radiological exposure of man from radioactivity in the Baltic Sea.

PubMed

Nielsen, S P; Bengtson, P; Bojanowsky, R; Hagel, P; Herrmann, J; Ilus, E; Jakobson, E; Motiejunas, S; Panteleev, Y; Skujina, A; Suplinska, M

1999-09-30

A radiological assessment has been carried out considering discharges of radioactivity to the Baltic Sea marine environment since 1950. The sources of radioactivity that have been evaluated are atmospheric nuclear-weapons fallout, fallout from the Chernobyl accident in 1986, discharges of radionuclides from Sellafield and La Hague transported into the Baltic Sea, and discharges of radionuclides from nuclear installations located in the Baltic Sea area. Dose rates from man-made radioactivity to individual members of the public (critical groups) have been calculated based on annual intake of seafood and beach occupancy time. The dose rates to individuals from the regions of the Bothnian Sea and Gulf of Finland are predicted to be larger than from any other area in the Baltic Sea due to the pattern of Chernobyl fallout. The dose rates are predicted to have peaked in 1986 at a value of 0.2 mSv year-1. Collective committed doses to members of the public have been calculated based on fishery statistics and predicted concentrations of radionuclides in biota and coastal sediments. The total collective dose from man-made radioactivity in the Baltic Sea is estimated at 2600 manSv, of which approximately two-thirds originate from Chernobyl fallout, approximately one-quarter from atmospheric nuclear-weapons fallout, approximately 8% from European reprocessing facilities, and approximately 0.04% from nuclear installations bordering the Baltic Sea area. An assessment of small-scale dumping of low-level radioactive waste in the Baltic Sea in the 1960s by Sweden and the Soviet Union has showed that doses to man from these activities are negligible. Dose rates and doses from natural radioactivity dominate except for the year 1986 where dose rates to individuals from Chernobyl fallout in some regions of the Baltic Sea approached those from natural radioactivity.

Evaluation of potential hazard exposure resulting from DOE waste treatment and disposal at Rollins Environmental Services, Baton Rouge, LA

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

Not Available

1992-04-01

The equivalent dose rate to populations potentially exposed to wastes shipped to Rollins Environmental Services, Baton Rouge, LA from Oak Ridge and Savannah River Operations of the Department of Energy was estimated. Where definitive information necessary to the estimation of a dose rate was unavailable, bounding assumptions were employed to ensure an overestimate of the actual dose rate experienced by the potentially exposed population. On this basis, it was estimated that a total of about 3.85 million pounds of waste was shipped from these DOE operations to Rollins with a maximum combined total activity of about 0.048 Curies. Populations nearmore » the Rollins site could potentially be exposed to the radionuclides in the DOE wastes via the air pathway after incineration of the DOE wastes or by migration from the soil after landfill disposal. AIRDOS was used to estimate the dose rate after incineration. RESRAD was used to estimate the dose rate after landfill disposal. Calculations were conducted with the estimated radioactive specie distribution in the wastes and, as a test of the sensitivity of the results to the estimated distribution, with the entire activity associated with individual radioactive species such as Cs-137, Ba-137, Sr-90, Co-60, U-234, U-235 and U-238. With a given total activity, the dose rates to nearby individuals were dominated by the uranium species.« less

Use of two doses of cloprostenol in different intervals for estrus synchronization in hair sheep under tropical conditions.

PubMed

de Carvalho Menezes de Almeida, Sheylla Foligno; Souza-Fabjan, Joanna Maria Gonçalves; Balaro, Mario Felipe Alvarez; Bragança, Gláucia Mota; Pinto, Pedro Henrique Nicolau; de Almeida, José Gabriel; Moura, Ana Beatriz Bossois; da Fonseca, Jeferson Ferreira; Brandão, Felipe Zandonadi

2018-02-01

This study evaluated the effect of two doses of prostaglandin at different intervals on reproductive parameters of crossbred ewes. In Experiment 1, 30 ewes received two doses of 120 μg cloprostenol at 7 (G 7 days ), 9 (G 9 days ), or 11.5 (G 11.5 days ) days apart. Ultrasound assessments were performed from the first and second cloprostenol administration for 5 days or ovulation detection. Estrus signs were checked by a teaser male. Plasma progesterone concentration was measured before each cloprostenol dose. In Experiment 2, 95 ewes were allocated into the same treatments and after the second dose, ewes in estrus were mated. At 30 days after breeding, pregnancy diagnosis was conducted and prolificacy was evaluated at lambing. In Experiment 1, at the first cloprostenol administration, 50% of ewes had an active CL and all showed estrus. At the second administration, 66.7% of ewes had an active CL and one did not present estrus. There was no difference (P > 0.05) after the second dose for as follows: overall estrous response (90%), interval from cloprostenol administration to estrous onset (42.0 ± 4.9 h), estrus duration (31.5 ± 2.1 h), ovulation rate (100.0%), and number of ovulations (1.5 ± 0.3). In Experiment 2, both pregnancy and prolificacy rates were similar (P > 0.05) for G 7 days (73.3; 145%), G 9 days (75.9; 125%), or G 11.5 days (75.9; 145%), leading to an overall pregnancy rate of 75.0% (66/88) and prolificacy rate of 137% . Therefore, the three treatments proposed were able to promote high pregnancy and prolificacy rates in crossbred ewes.

Radionuclide concentrations in soil and lifetime cancer risk due to gamma radioactivity in Kirklareli, Turkey.

PubMed

Taskin, H; Karavus, M; Ay, P; Topuzoglu, A; Hidiroglu, S; Karahan, G

2009-01-01

The objective of this study is to evaluate and map soil radionuclides' activity concentrations and environmental outdoor gamma dose rates (terrestrial and cosmic) in Kirklareli, Turkey. The excess lifetime cancer risks are also calculated. Outdoor gamma dose rates were determined in 230 sampling stations and soil samples were taken from 177 locations. The coordinates of the readings were determined by the Global Positioning System (GPS). The outdoor gamma dose rates were determined by Eberline smart portable device (ESP-2) and measurements were taken in air for two minutes at 1m from the ground. The average outdoor gamma dose rate was 118+/-34nGyh(-1). Annual effective gamma dose of Kirklareli was 144microSv and the excess lifetime cancer risk of 5.0x10(-4). Soil samples were analyzed by gamma spectroscopy. The average 226Ra, 238U, 232Th, 137Cs, and 40K activities were 37+/-18Bqkg(-1), 28+/-13Bqkg(-1), 40+/-18Bqkg(-1), 8+/-5Bqkg(-1) and 667+/-281Bqkg(-1), respectively. The average soil radionuclides' concentrations of Kirklareli were within the worldwide range although some extreme values had been determined. Annual effective gamma doses and the excess lifetime risks of cancer were higher than the world's average.

Radiological characteristics of MRI-based VIP polymer gel under carbon beam irradiation

NASA Astrophysics Data System (ADS)

Maeyama, T.; Fukunishi, N.; Ishikawa, K. L.; Furuta, T.; Fukasaku, K.; Takagi, S.; Noda, S.; Himeno, R.; Fukuda, S.

2015-02-01

We study the radiological characteristics of VIP polymer gel dosimeters under carbon beam irradiation with energy of 135 and 290 AMeV. To evaluate dose response of VIP polymer gels, the transverse (or spin-spin) relaxation rate R2 of the dosimeters measured by magnetic resonance imaging (MRI) as a function of linear energy transfer (LET), rather than penetration depth, as is usually done in previous reports. LET is evaluated by use of the particle transport simulation code PHITS. Our results reveal that the dose response decreases with increasing dose-averaged LET and that the dose response-LET relation also varies with incident carbon beam energy. The latter can be explained by taking into account the contribution from fragmentation products.

Dose verification for respiratory-gated volumetric modulated arc therapy (VMAT)

PubMed Central

Qian, Jianguo; Xing, Lei; Liu, Wu; Luxton, Gary

2011-01-01

A novel commercial medical linac system (TrueBeam™, Varian Medical Systems, Palo Alto, CA) allows respiratory-gated volumetric modulated arc therapy (VMAT), a new modality for treating moving tumors with high precision and improved accuracy by allowing for regular motion associated with a patient's breathing during VMAT delivery. The purpose of this work is to adapt a previously-developed dose reconstruction technique to evaluate the fidelity of VMAT treatment during gated delivery under clinic-relevant periodic motion related to patient breathing. A Varian TrueBeam system was used in this study. VMAT plans were created for three patients with lung or pancreas tumors. Conventional 6 MV and 15 MV beams with flattening filter and high dose-rate 10 MV beams with no flattening filter were used in these plans. Each patient plan was delivered to a phantom first without gating and then with gating for three simulated respiratory periods (3, 4.5 and 6 seconds). Using the adapted log file-based dose reconstruction procedure supplemented with ion chamber array (Seven29™, PTW, Freiburg, Germany) measurements, the delivered dose was used to evaluate the fidelity of gated VMAT delivery. Comparison of Seven29 measurements with and without gating showed good agreement with gamma-index passing rates above 99% for 1%/1mm dose accuracy/distance-to-agreement criteria. With original plans as reference, gamma-index passing rates were 100% for the reconstituted plans (1%/1 mm criteria) and 93.5–100% for gated Seven29 measurements (3%/3 mm criteria). In the presence of leaf error deliberately introduced into the gated delivery of a pancreas patient plan, both dose reconstruction and Seven29 measurement consistently indicated substantial dosimetric differences from the original plan. In summary, a dose reconstruction procedure was demonstrated for evaluating the accuracy of respiratory-gated VMAT delivery. This technique showed that under clinical operation, the TrueBeam system faithfully realized treatment plans with gated delivery. This methodology affords a useful tool for machine and patient-specific quality assurance of the newly available respiratory-gated VMAT. PMID:21753232

Inverse Planning Approach for 3-D MRI-Based Pulse-Dose Rate Intracavitary Brachytherapy in Cervix Cancer

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

Chajon, Enrique; Dumas, Isabelle; Touleimat, Mahmoud B.Sc.

2007-11-01

Purpose: The purpose of this study was to evaluate the inverse planning simulated annealing (IPSA) software for the optimization of dose distribution in patients with cervix carcinoma treated with MRI-based pulsed-dose rate intracavitary brachytherapy. Methods and Materials: Thirty patients treated with a technique using a customized vaginal mold were selected. Dose-volume parameters obtained using the IPSA method were compared with the classic manual optimization method (MOM). Target volumes and organs at risk were delineated according to the Gynecological Brachytherapy Group/European Society for Therapeutic Radiology and Oncology recommendations. Because the pulsed dose rate program was based on clinical experience with lowmore » dose rate, dwell time values were required to be as homogeneous as possible. To achieve this goal, different modifications of the IPSA program were applied. Results: The first dose distribution calculated by the IPSA algorithm proposed a heterogeneous distribution of dwell time positions. The mean D90, D100, and V100 calculated with both methods did not differ significantly when the constraints were applied. For the bladder, doses calculated at the ICRU reference point derived from the MOM differed significantly from the doses calculated by the IPSA method (mean, 58.4 vs. 55 Gy respectively; p = 0.0001). For the rectum, the doses calculated at the ICRU reference point were also significantly lower with the IPSA method. Conclusions: The inverse planning method provided fast and automatic solutions for the optimization of dose distribution. However, the straightforward use of IPSA generated significant heterogeneity in dwell time values. Caution is therefore recommended in the use of inverse optimization tools with clinical relevance study of new dosimetric rules.« less

Monte Carlo calculation of the neutron dose to a fetus at commercial flight altitudes

NASA Astrophysics Data System (ADS)

Alves, M. C.; Galeano, D. C.; Santos, W. S.; Hunt, John G.; d'Errico, Francesco; Souza, S. O.; de Carvalho Júnior, A. B.

2017-11-01

Aircrew members are exposed to primary cosmic rays as well as to secondary radiations from the interaction of cosmic rays with the atmosphere and with the aircraft. The radiation field at flight altitudes comprises neutrons, protons, electrons, positrons, photons, muons and pions. Generally, 50% of the effective dose to airplane passengers is due to neutrons. Care must be taken especially with pregnant aircrew members and frequent fliers so that the equivalent dose to the fetus will not exceed prescribed limits during pregnancy (1 mSv according to ICRP, and 5 mSv according to NCRP). Therefore, it is necessary to evaluate the equivalent dose to a fetus in the maternal womb. Up to now, the equivalent dose rate to a fetus at commercial flight altitudes was obtained using stylized pregnant-female phantom models. The aim of this study was calculating neutron fluence to dose conversion coefficients for a fetus of six months of gestation age using a new, realistic pregnant-female mesh-phantom. The equivalent dose rate to a fetus during an intercontinental flight was also calculated by folding our conversion coefficients with published spectral neutron flux data. The calculated equivalent dose rate to the fetus was 2.35 μSv.h-1, that is 1.5 times higher than equivalent dose rates reported in the literature. The neutron fluence to dose conversion coefficients for the fetus calculated in this study were 2.7, 3.1 and 3.9 times higher than those from previous studies using fetus models of 3, 6 and 9 months of gestation age, respectively. The differences between our study and data from the literature highlight the importance of using more realistic anthropomorphic phantoms to estimate doses to a fetus in pregnant aircrew members.

Phase I dose-escalation studies of roniciclib, a pan-cyclin-dependent kinase inhibitor, in advanced malignancies.

PubMed

Bahleda, Rastislav; Grilley-Olson, Juneko E; Govindan, Ramaswamy; Barlesi, Fabrice; Greillier, Laurent; Perol, Maurice; Ray-Coquard, Isabelle; Strumberg, Dirk; Schultheis, Beate; Dy, Grace K; Zalcman, Gérard; Weiss, Glen J; Walter, Annette O; Kornacker, Martin; Rajagopalan, Prabhu; Henderson, David; Nogai, Hendrik; Ocker, Matthias; Soria, Jean-Charles

2017-06-06

To evaluate safety, pharmacokinetics, and maximum tolerated dose of roniciclib in patients with advanced malignancies, with dose expansion to evaluate clinical benefit at the recommended phase II dose (RP2D). Two phase I dose-escalation studies evaluated two roniciclib dosing schedules: 3 days on/4 days off or 4 weeks on/2 weeks off. The expansion phase included patients with small-cell lung cancer (SCLC), ovarian cancer, or tumour mutations involving the CDK signalling pathway. Ten patients were evaluable in the 4 weeks on/2 weeks off schedule (terminated following limited tolerability) and 47 in the 3 days on/4 days off schedule dose-escalation cohorts. On the 3 days on/4 days off schedule, RP2D was 5 mg twice daily in solid tumours (n=40); undetermined in lymphoid malignancies (n=7). Common roniciclib-related adverse events included nausea (76.6%), fatigue (65.8%), diarrhoea (63.1%), and vomiting (57.7%). Roniciclib demonstrated rapid absorption and dose-proportional increase in exposure. One partial response (1.0%) was observed. In RP2D expansion cohorts, the disease control rate (DCR) was 40.9% for patients with ovarian cancer (n=25), 17.4% for patients with SCLC (n=33), and 33.3% for patients with CDK-related tumour mutations (n=6). Roniciclib demonstrated an acceptable safety profile and moderate DCR in 3 days on/4 days off schedule.

Cytogenetic damage analysis in mice chronically exposed to low-dose internal tritium beta-particle radiation.

PubMed

Roch-Lefèvre, Sandrine; Grégoire, Eric; Martin-Bodiot, Cécile; Flegal, Matthew; Fréneau, Amélie; Blimkie, Melinda; Bannister, Laura; Wyatt, Heather; Barquinero, Joan-Francesc; Roy, Laurence; Benadjaoud, Mohamed; Priest, Nick; Jourdain, Jean-René; Klokov, Dmitry

2018-06-08

The aim of this study was to carry out a comprehensive examination of potential genotoxic effects of low doses of tritium delivered chronically to mice and to compare these effects to the ones resulting from equivalent doses of gamma-irradiation. Mice were chronically exposed for one or eight months to either tritiated water (HTO) or organically bound tritium (OBT) in drinking water at concentrations of 10 kBq/L, 1 MBq/L or 20 MBq/L. Dose rates of internal β-particle resulting from such tritium treatments were calculated and matching external gamma-exposures were carried out. We measured cytogenetic damage in bone marrow and in peripheral blood lymphocytes (PBLs) and the cumulative tritium doses (0.009 - 181 mGy) were used to evaluate the dose-response of OBT in PBLs, as well as its relative biological effectiveness (RBE). Neither tritium, nor gamma exposures produced genotoxic effects in bone marrow. However, significant increases in chromosome damage rates in PBLs were found as a result of chronic OBT exposures at 1 and 20 M Bq/L, but not at 10 kBq/L. When compared to an external acute gamma-exposure ex vivo , the RBE of OBT for chromosome aberrations induction was evaluated to be significantly higher than 1 at cumulative tritium doses below 10 mGy. Although found non-existent at 10 kBq/L (the WHO limit), the genotoxic potential of low doses of tritium (>10 kBq/L), mainly OBT, may be higher than currently assumed.

Characterization and long-term persistence of immune response following two doses of an AS03A-adjuvanted H1N1 influenza vaccine in healthy Japanese adults.

PubMed

Ikematsu, Hideyuki; Nagai, Hideaki; Kawashima, Masahiro; Kawakami, Yasunobu; Tenjinbaru, Kazuyoshi; Li, Ping; Walravens, Karl; Gillard, Paul; Roman, François

2012-02-01

Background Long-term persistence of immune response and safety of two doses of an A/California/07/2009 H1N1 pandemic influenza vaccine adjuvanted with AS03 (an α-tocopherol oil-in-water emulsion-based Adjuvant System) administered 21 d apart was evaluated in Japanese adults [NCT00989612]. Methods One-hundred healthy subjects aged 20-64 y (stratified [1:1] into two age strata 20-40 y and 41-64 y) received 21 d apart, two doses of AS03-adjuvanted 3.75µg haemagglutinin (HA) H1N1 2009 vaccine. Immunogenicity data by haemagglutination inhibition (HI) assay six months after the first vaccine dose (Day 182) and microneutralization assay following each of the two vaccine doses (Days 21 and 42) and at Day 182 are reported here. Results Persistence of strong HI immune response was observed at Day 182 that met the US and European regulatory thresholds for pandemic influenza vaccines (seroprotection rate: 95%; seroconversion rate: 93%; geometric mean fold-rise: 20). The neutralizing antibody response against the A/Netherlands/602/2009 strain (antigenically similar to vaccine-strain) persisted for at least up to Day 182 (vaccine response rate: 76%; geometric mean titer: 114.4) and paralleled the HI immune response at all time points. No marked difference was observed in HI antibody persistence and neutralising antibody response between the two age strata. The vaccine had a clinically-acceptable safety profile. Conclusion Two priming doses of H1N1 2009 pandemic influenza vaccine induced an immune response persisting for at least six months after the first vaccine dose. This could be beneficial in evaluating the importance and effect of vaccination with this AS03-adjuvanted pandemic influenza vaccine.

Once daily oral mesalamine compared to conventional dosing for induction and maintenance of remission in ulcerative colitis: a systematic review and meta-analysis.

PubMed

Feagan, Brian G; MacDonald, John K

2012-09-01

We systematically reviewed and compared the efficacy and safety of once daily (OD) mesalamine to conventional dosing for induction and maintenance of remission in ulcerative colitis (UC). A literature search to January 2012 identified all applicable randomized trials. Study quality was evaluated using the Cochrane risk of bias tool. The GRADE criteria were used to assess the overall quality of the evidence. Studies were subgrouped by formulation for meta-analysis. Eleven studies that evaluated 4070 patients were identified. The risk of bias was low for most factors, although five studies were single-blind and one was open-label. No difference was observed between the dosing strategies in the proportion of patients with clinical remission (relative risk [RR] 0.95; 95% confidence interval [CI] 0.82-1.10), clinical improvement (RR 0.87 95% CI 0.68-1.10), or relapse at 6 (RR 1.10; 95% CI 0.83-1.46) or 12 months (RR 0.92; 95% CI 0.83-1.03). Subgroup analyses showed no important differences in efficacy. No significant difference was demonstrated in rates of medication adherence or adverse events between OD and conventional dosing. OD mesalamine appears to be as effective and safe as conventional dosing for both the treatment of mild to moderately active UC and for maintenance of remission in quiescent UC. The failure to demonstrate a superior rate of adherence to OD dosing may be due to the high rate of adherence observed in the clinical trials environment. Future research should assess the value of OD dosing in community settings. Copyright © 2012 Crohn's & Colitis Foundation of America, Inc.

Effect of Jiangzhi tablet on gastrointestinal propulsive function in mice

NASA Astrophysics Data System (ADS)

Wang, Xiangrong; Geng, Xiuli; Zhao, Jingsheng; Fan, Lili; Zhang, Zhengchen

2018-04-01

This paper aims to study the effect of lipid-lowering tablets on gastric emptying and small intestinal propulsion in mice. Mice were randomly divided into control group, Digestant Pill group, Jiangzhi tablet group, middle dose and small dose, the mice gastric emptying phenolsulfonphthalein, gastric residual rate of phenol red indicator to evaluate the gastric emptying rate, residual rate of detection in mouse stomach; small intestine propulsion and selection of carbon ink as the experimental index. Effects were observed to promote the function of normal mice gastric emptying and intestine. The gastric emptying and small intestinal motor function of normal mice were all promoted by each administration group, and the effect was most obvious in small dose group. The effect of reducing blood lipid on gastrointestinal motility of mice ware obviously enhanced.

Radiosensitivity study and radiation effects on morphology characterization of grey oyster mushroom Pleurotus sajor-caju

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

Rashid, Rosnani Abdul; Awang, Mat Rasol; Mohamad, Azhar

2014-09-03

Radiosensitive dosage and morphology characterization of irradiated grey oyster mushroom Pleurotus sajor-caju by gamma rays was investigated due to effects of irradiation. In order to establish the effect, mycelium of P. sajor-caju was irradiated by gamma rays at dose 0.1 to 8.0 kGy with dose rate 0.227 Gy sec{sup −1}. The irradiation of mycelia was carried out at the radiation facility in Malaysian Nuclear Agency. The radiosensitivity study was performed by evaluating the percentage of survival irradiated mycelia. The lethal dose of the mycelium P. sajor-caju was determined at 4.0 kGy and LD{sub 50} to be equal at 2.2 kGy.more » The radiation effects on morphology were evaluated based on growth rate of irradiated mycelia, mycelia types, colonization period on substrate, morphology of fruit bodies and yields. The results shown growth rate of irradiated mycelium was slightly lower than the control and decreased as the dose increased. Irradiation was found can induced the primordia formation on PDA and the BE of irradiated seed is higher than to control. The irradiation is proven to be useful for generating new varieties of mushroom with commercial value to the industry.« less

Technical basis for implementation of remote reading capabilities for radiological control instruments at tank farms

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

PIERSON, R.M.

1999-10-27

This document provides the technical basis for use of remote reading capabilities with radiological control instruments at River Protection Project facilities. The purpose of this document is to evaluate applications of remote reading capabilities with Radiological Control instrumentation to allow continuous monitoring of radiation dose rates at River Protection Project (RPP) facilities. In addition this document provides a technical basis and implementing guidelines for remote monitoring of dose rates and their potential contribution to maintaining radiation exposures ALARA.

Modern dosimetric tools for 60Co irradiation at high containment laboratories

PubMed Central

Twardoski, Barri; Feldmann, Heinz; Bloom, Marshall E.; Ward, Joe

2011-01-01

Purpose To evaluate an innovative photo-fluorescent film as a routine dosimetric tool during 60Co irradiations at a high containment biological research laboratory, and to investigate whether manufacturer-provided chamber exposure rates can be used to accurately administer a prescribed dose to biological specimens. Materials and methods Photo-fluorescent, lithium fluoride film dosimeters and National Institutes of Standards and Technology (NIST) transfer dosimeters were co-located in a self-shielded 60Co irradiator and exposed to γ-radiation with doses ranging from 5–85 kGy. Film dose-response relationships were developed for varying temperatures simulating conditions present when irradiating infectious biological specimens. Dose measurement results from NIST transfer dosimeters were compared to doses predicted using manufacturer-provided irradiator chamber exposure rates. Results The film dosimeter exhibited a photo-fluorescent response signal that was consistent and nearly linear in relationship to γ-radiation exposure over a wide dose range. The dosimeter response also showed negligible effects from dose fractionization and humidity. Significant disparities existed between manufacturer-provided chamber exposure rates and actual doses administered. Conclusion This study demonstrates the merit of utilizing dosimetric tools to validate the process of exposing dangerous and exotic biological agents to γ-radiation at high containment laboratories. The film dosimeter used in this study can be utilized to eliminate potential for improperly administering γ-radiation doses. PMID:21961968

Effect of the dose of exogenous fibrolytic enzyme preparations on preingestive fiber hydrolysis, ruminal fermentation, and in vitro digestibility of bermudagrass haylage.

PubMed

Romero, J J; Zarate, M A; Adesogan, A T

2015-01-01

Our objectives were to evaluate the effects of the dose rates of 5 Trichoderma reesei and Aspergillus oryzae exogenous fibrolytic enzymes (EFE; 1A, 2A, 11C, 13D, and 15D) on in vitro digestibility, fermentation characteristics, and preingestive hydrolysis of bermudagrass haylage and to identify the optimal dose of each EFE for subsequent in vitro and in vivo studies. In experiment 1, EFE were diluted in citrate-phosphate buffer (pH 6) and applied in quadruplicate in each of 2 runs at 0× (control), 0.5×, 1×, 2×, and 3×; where 1× was the respective manufacturer-recommended dose (2.25, 2.25, 10, 15, and 15g of EFE/kg of dry matter). The suspension was incubated for 24h at 25°C and for a further 24h at 39°C after the addition of ruminal fluid. In experiment 2, a similar approach to that in experiment 1 was used to evaluate simulated preingestive effects, except that sodium azide (0.02% wt/vol) was added to the EFE solution. The suspension was incubated for 24h at 25°C and then 15mL of water was added before filtration to extract water-soluble compounds. For both experiments, data for each enzyme were analyzed separately as a completely randomized block design with a model that included effects of EFE dose, run, and their interaction. In experiment 1, increasing the EFE dose rate nonlinearly increased the DM digestibility of 1A, 2A, 11C, and 13D and the neutral detergent fiber digestibility (NDFD) of 1A, 2A, 11C, and 13D. Optimal doses of 1A, 2A, 11C, 13D, and 15D, as indicated by the greatest increases in NDFD at the lowest dose tested, were 2×, 2×, 1×, 0.5×, and 0.5×, respectively. Increasing the dose rate of 2A, 11C, and 13D nonlinearly increased concentrations of total volatile fatty acids and propionate (mM), decreased their acetate-to-propionate ratios and linearly decreased those of samples treated with 1A and 15D. In experiment 2, increasing the dose rate of each EFE nonlinearly decreased concentrations of netural detergent fiber; also, increasing the dose rate of 1A, 2A, 11C, and 1D nonlinearly increased concentrations of water-soluble carbohydrates and free ferulic acid (μg/g). Application of increasing doses of the EFE increased NDF hydrolysis, NDFD, and ruminal fluid fermentation of bermudagrass haylage, but the optimal dose varied with the EFE. Copyright © 2015 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

THE UNIQUE VALUE OF BREATH BIOMARKERS FOR ESTIMATING PHAMACOKINETIC RATE CONSTANTS AND BODY BURDEN FROM RANDOM/INTERMITTENT DOSE

EPA Science Inventory

Biomarker measurements are used in three ways: 1) evaluating the time course and distribution of a chemical in the body, 2) estimating previous exposure or dose, and 3) assessing disease state. Blood and urine measurements are the primary methods employed. Of late, it has been ...

Mathematical optimization of high dose-rate brachytherapy—derivation of a linear penalty model from a dose-volume model

NASA Astrophysics Data System (ADS)

Morén, B.; Larsson, T.; Carlsson Tedgren, Å.

2018-03-01

High dose-rate brachytherapy is a method for cancer treatment where the radiation source is placed within the body, inside or close to a tumour. For dose planning, mathematical optimization techniques are being used in practice and the most common approach is to use a linear model which penalizes deviations from specified dose limits for the tumour and for nearby organs. This linear penalty model is easy to solve, but its weakness lies in the poor correlation of its objective value and the dose-volume objectives that are used clinically to evaluate dose distributions. Furthermore, the model contains parameters that have no clear clinical interpretation. Another approach for dose planning is to solve mixed-integer optimization models with explicit dose-volume constraints which include parameters that directly correspond to dose-volume objectives, and which are therefore tangible. The two mentioned models take the overall goals for dose planning into account in fundamentally different ways. We show that there is, however, a mathematical relationship between them by deriving a linear penalty model from a dose-volume model. This relationship has not been established before and improves the understanding of the linear penalty model. In particular, the parameters of the linear penalty model can be interpreted as dual variables in the dose-volume model.

Comparative dosimetric characterization for different types of detectors in high-energy electron beams

NASA Astrophysics Data System (ADS)

Lee, Chang Yeol; Kim, Woo Chul; Kim, Hun Jeong; Huh, Hyun Do; Park, Seungwoo; Choi, Sang Hyoun; Kim, Kum Bae; Min, Chul Kee; Kim, Seong Hoon; Shin, Dong Oh

2017-02-01

The purpose of this study is to perform a comparison and on analysis of measured dose factor values by using various commercially available high-energy electron beam detectors to measure dose profiles and energy property data. By analyzing the high-energy electron beam data from each detector, we determined the optimal detector for measuring electron beams in clinical applications. The dose linearity, dose-rate dependence, percentage depth dose, and dose profile of each detector were measured to evaluate the dosimetry characteristics of high-energy electron beams. The dose profile and the energy characteristics of high-energy electron beams were found to be different when measured by different detectors. Through comparison with other detectors based on the analyzed data, the microdiamond detector was found to have outstanding dose linearity, a low dose-rate dependency, and a small effective volume. Thus, this detector has outstanding spatial resolution and is the optimal detector for measuring electron beams. Radiation therapy results can be improved and related medical accidents can be prevented by using the procedure developed in this research in clinical practice for all beam detectors when measuring the electron beam dose.

Evaluation of the immunogenicity of the quadrivalent HPV vaccine using 2 versus 3 doses at month 21: An epidemiological surveillance mechanism for alternate vaccination schemes

PubMed Central

Hernández-Ávila, Mauricio; Torres-Ibarra, Leticia; Stanley, Margaret; Salmerón, Jorge; Cruz-Valdez, Aurelio; Muñoz, Nubia; Herrero, Rolando; Villaseñor-Ruíz, Ignacio F; Lazcano-Ponce, Eduardo

2016-01-01

The cost of HPV vaccines and the need for 3 doses remains a barrier for their inclusion in routine vaccination schedules for girls in low and middle income countries. In a non-inferiority study, we aimed to compare the immunogenicity of a standard 3 doses and a 2 doses schedule. We enrolled 450 participants in an open-label non-randomized clinical trial to evaluate the immunogenicity induced at different ages by the licensed HPV6/11/16/18 quadrivalent vaccine in a 2 doses schedule (0–6 months, n = 150 girls aged 9–10 y) and 3 doses schedule (0, 2, and 6 months; n = 150 girls aged 9–10 y and n=150 women aged 18 to 24 years). To assess the antibody response, blood samples were obtained at Month 7 and 21 after the first vaccination from participants in all study groups. cLIA testing was performed at Merck Research Laboratories. Antibody levels were expressed as milli-Merck units (mMU) per ml. Primary outcome was non-inferiority (95% CI, lower bound >0.5) of the geometric mean titers (GMT) ratios for HPV6, HPV11, HPV16 and HPV18 antibodies 7 and 21 months after the first dose among girls receiving 2 doses compared with young women and girls receiving 3 doses. All vaccinees were seropositive for both HPV16 and HPV18 antibodies at month 7. At month 21, 98.5 and 56.6% of women 18–24 y old were seropositive for HPV16 and 18, respectively. For girls in the three doses group, seropositivity rates were 99.3 and 86.3% for HPV16 and 18, respectively. For girls in the two doses group rates were 99.3 and 70.2% for HPV16 and 18, respectively. The two doses schedule was non-inferior compared to the 3 doses schedule in same-age girls and to the group of adult women after 21 months of the first vaccine dose. Our results are in agreement with similar trials evaluating the immune response of a 2 doses schedule of both HPV vaccines, supporting the recent WHO recommendation as well as the Mexican policy to incorporate the 2 doses schedule for girls aged 9–11 y. PMID:26211489

A study of the time of hospital discharge of differentiated thyroid cancer patients after receiving iodine-131 for thyroid remnant ablation treatment.

PubMed

Azizmohammadi, Zahra; Tabei, Faraj; Shafiei, Babak; Babaei, Ali Akbar; Jukandan, Seyed Mohsen Qutbi; Naghshine, Reza; Javadi, Hamid; Nabipour, Iraj; Assadi, Majid; Asli, Isa Neshandar

2013-01-01

The aim of this study was to measure the radiation exposure rate from differentiated thyroid carcinoma (DTC) patients who had received iodine-131 ((131)I) treatment, and to evaluate hospital discharge planning in relation to three different sets of regulations. We studied 100 patients, 78 females and 22 males, aged 13 to 79 years (mean 44.40±15.83 years) with DTC, in three Groups who were treated with 3.7, 5.5 or 7.4GBq of (131)I, respectively. The external whole-body dose rates following oral administration of (131)I were measured after each one of the first three hospitalization days. A multivariant linear analysis was performed, considering exposure rates as dependent variables to the administered dose for treatment, age, gender, regional and/or distant metastases, thyroglobulin (Tg), antibodies to Tg and thyroid remnant in the three dose groups. We found that the exposure rates after each of the three first days of hospitalization were 30, 50 and 70μSvh-1 at 1m. All our DTC patients had an acceptable dose rate on days 2 and 3 that allowed their hospital discharge. After only 1 day of hospitalization, just 3/11 cases showed not permissible exposure rates above 70μSvh-1. In conclusion, it is the opinion of the authors that after measuring the exposure rates, most treated, DTC patients could be discharged after only one day of hospitalization, even some of those treated with high doses of (131)I (7.4GBq). Patients, who received the higher doses of (131)I, should not be released before their individual exposure rate is measured.

SU-C-BRD-07: Three-Dimensional Dose Reconstruction in the Presence of Inhomogeneities Using Fast EPID-Based Back-Projection Method

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

Ren, Q; Cao, R; Pei, X

2015-06-15

Purpose: Three-dimensional dose verification can detect errors introduced by the treatment planning system (TPS) or differences between planned and delivered dose distribution during the treatment. The aim of the study is to extend a previous in-house developed three-dimensional dose reconstructed model in homogeneous phantom to situtions in which tissue inhomogeneities are present. Methods: The method was based on the portal grey images from an electronic portal imaging device (EPID) and the relationship between beamlets and grey-scoring voxels at the position of the EPID. The relationship was expressed in the form of grey response matrix that was quantified using thickness-dependence scattermore » kernels determined by series of experiments. From the portal grey-value distribution information measured by the EPID the two-dimensional incident fluence distribution was reconstructed based on the grey response matrix using a fast iterative algorithm. The accuracy of this approach was verified using a four-field intensity-modulated radiotherapy (IMRT) plan for the treatment of lung cancer in anthopomorphic phantom. Each field had between twenty and twenty-eight segments and was evaluated by comparing the reconstructed dose distribution with the measured dose. Results: The gamma-evaluation method was used with various evaluation criteria of dose difference and distance-to-agreement: 3%/3mm and 2%/2 mm. The dose comparison for all irradiated fields showed a pass rate of 100% with the criterion of 3%/3mm, and a pass rate of higher than 92% with the criterion of 2%/2mm. Conclusion: Our experimental results demonstrate that our method is capable of accurately reconstructing three-dimensional dose distribution in the presence of inhomogeneities. Using the method, the combined planning and treatment delivery process is verified, offing an easy-to-use tool for the verification of complex treatments.« less

Selective enhancement of fentanyl-induced antinociception by the delta agonist SNC162 but not by ketamine in rhesus monkeys: Further evidence supportive of delta agonists as candidate adjuncts to mu opioid analgesics.

PubMed

Banks, Matthew L; Folk, John E; Rice, Kenner C; Negus, S Stevens

2010-12-01

Mu-opioid receptor agonists such as fentanyl are effective analgesics, but their clinical use is limited by untoward effects. Adjunct medications may improve the effectiveness and/or safety of opioid analgesics. This study compared interactions between fentanyl and either the noncompetitive N-methyl-D-aspartate (NMDA) glutamate receptor antagonist ketamine or the delta-opioid receptor agonist SNC162 [(+)-4-[(alphaR)-alpha-[(2S,5R)-2,5-dimethyl-4-(2-propenyl)-1-piperazinyl]-(3-phenyl)methyl]-N,N-diethylbenzamide] in two behavioral assays in rhesus monkeys. An assay of thermal nociception evaluated tail-withdrawal latencies from water heated to 50 and 54°C. An assay of schedule-controlled responding evaluated response rates maintained under a fixed-ratio 30 schedule of food presentation. Effects of each drug alone and of three mixtures of ketamine+fentanyl (22:1, 65:1, 195:1 ketamine/fentanyl) or SNC162+fentanyl (59:1, 176:1, 528:1 SNC162/fentanyl) were evaluated in each assay. All drugs and mixtures dose-dependently decreased rates of food-maintained responding, and drug proportions in the mixtures were based on relative potencies in this assay. Ketamine and SNC162 were inactive in the assay of thermal antinociception, but fentanyl and all mixtures produced dose-dependent antinociception. Drug interactions were evaluated using dose-addition and dose-ratio analysis. Dose-addition analysis revealed that interactions for all ketamine/fentanyl mixtures were additive in both assays. SNC162/fentanyl interactions were usually additive, but one mixture (176:1) produced synergistic antinociception at 50°C. Dose-ratio analysis indicated that ketamine failed to improve the relative potency of fentanyl to produce antinociception vs. rate suppression, whereas two SNC162/fentanyl mixtures (59:1 and 176:1) increased the relative potency of fentanyl to produce antinociception. These results suggest that delta agonists may produce more selective enhancement than ketamine of mu agonist-induced antinociception. Copyright © 2010 Elsevier Inc. All rights reserved.

Micron MT29F128G08AJAAA 128GB Asynchronous Flash Memory Total Ionizing Dose Characterization Test Report

NASA Technical Reports Server (NTRS)

Campola, Michael; Wyrwas, Edward

2017-01-01

The purpose of this test was to characterize the Micron MT29F128G08AJAAAs parameter degradation for total dose response and to evaluate and compare lot date codes for sensitivity. In the test, the device was exposed to both low dose and high dose rate (HDR) irradiations using gamma radiation. Device parameters such as leakage currents, quantity of upset bits and overall chip and die health were investigated to determine which lot is more robust.

Paediatric nurses' adherence to the double-checking process during medication administration in a children's hospital: an observational study.

PubMed

Alsulami, Zayed; Choonara, Imti; Conroy, Sharon

2014-06-01

To evaluate how closely double-checking policies are followed by nurses in paediatric areas and also to identify the types, frequency and rates of medication administration errors that occur despite the double-checking process. Double-checking by two nurses is an intervention used in many UK hospitals to prevent or reduce medication administration errors. There is, however, insufficient evidence to either support or refute the practice of double-checking in terms of medication error risk reduction. Prospective observational study. This was a prospective observational study of paediatric nurses' adherence to the double-checking process for medication administration from April-July 2012. Drug dose administration events (n = 2000) were observed. Independent drug dose calculation, rate of administering intravenous bolus drugs and labelling of flush syringes were the steps with lowest adherence rates. Drug dose calculation was only double-checked independently in 591 (30%) drug administrations. There was a statistically significant difference in nurses' adherence rate to the double-checking steps between weekdays and weekends in nine of the 15 evaluated steps. Medication administration errors (n = 191) or deviations from policy were observed, at a rate of 9·6% of drug administrations. These included 64 drug doses, which were left for parents to administer without nurse observation. There was variation between paediatric nurses' adherence to double-checking steps during medication administration. The most frequent type of administration errors or deviation from policy involved the medicine being given to the parents to administer to the child when the nurse was not present. © 2013 John Wiley & Sons Ltd.

High doses of dextromethorphan, an NMDA antagonist, produce effects similar to classic hallucinogens

PubMed Central

Carter, Lawrence P.; Johnson, Matthew W.; Mintzer, Miriam Z.; Klinedinst, Margaret A.; Griffiths, Roland R.

2013-01-01

Rationale Although reports of dextromethorphan (DXM) abuse have increased recently, few studies have examined the effects of high doses of DXM. Objective This study in humans evaluated the effects of supratherapeutic doses of DXM and triazolam. Methods Single, acute, oral doses of DXM (100, 200, 300, 400, 500, 600, 700, 800 mg/70 kg), triazolam (0.25, 0.5 mg/70kg), and placebo were administered to twelve healthy volunteers with histories of hallucinogen use, under double-blind conditions, using an ascending dose run-up design. Subjective, behavioral, and physiological effects were assessed repeatedly after drug administration for 6 hours. Results Triazolam produced dose-related increases in subject-rated sedation, observer-rated sedation, and behavioral impairment. DXM produced a profile of dose-related physiological and subjective effects differing from triazolam. DXM effects included increases in blood pressure, heart rate, and emesis, increases in observer-rated effects typical of classic hallucinogens (e.g. distance from reality, visual effects with eyes open and closed, joy, anxiety), and participant ratings of stimulation (e.g. jittery, nervous), somatic effects (e.g. tingling, headache), perceptual changes, end-of-session drug liking, and mystical-type experience. After 400 mg/70kg DXM, 11 of 12 participants indicated on a pharmacological class questionnaire that they thought they had received a classic hallucinogen (e.g. psilocybin). Drug effects resolved without significant adverse effects by the end of the session. In a 1-month follow up volunteers attributed increased spirituality and positive changes in attitudes, moods, and behavior to the session experiences. Conclusions High doses of DXM produced effects distinct from triazolam and had characteristics that were similar to the classic hallucinogen psilocybin. PMID:22526529

Islet oxygen consumption rate (OCR) dose predicts insulin independence for first clinical islet allotransplants

PubMed Central

Kitzmann, JP; O’Gorman, D; Kin, T; Gruessner, AC; Senior, P; Imes, S; Gruessner, RW; Shapiro, AMJ; Papas, KK

2014-01-01

Human islet allotransplant (ITx) for the treatment of type 1 diabetes is in phase III clinical registration trials in the US and standard of care in several other countries. Current islet product release criteria include viability based on cell membrane integrity stains, glucose stimulated insulin release (GSIR), and islet equivalent (IE) dose based on counts. However, only a fraction of patients transplanted with islets that meet or exceed these release criteria become insulin independent following one transplant. Measurements of islet oxygen consumption rate (OCR) have been reported as highly predictive of transplant outcome in many models. In this paper we report on the assessment of clinical islet allograft preparations using islet oxygen consumption rate (OCR) dose (or viable IE dose) and current product release assays in a series of 13 first transplant recipients. The predictive capability of each assay was examined and successful graft function was defined as 100% insulin independence within 45 days post-transplant. Results showed that OCR dose was most predictive of CTO. IE dose was also highly predictive, while GSIR and membrane integrity stains were not. In conclusion, OCR dose can predict CTO with high specificity and sensitivity and is a useful tool for evaluating islet preparations prior to clinical ITx. PMID:25131089

SU-E-T-113: Dose Distribution Using Respiratory Signals and Machine Parameters During Treatment

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

Imae, T; Haga, A; Saotome, N

Purpose: Volumetric modulated arc therapy (VMAT) is a rotational intensity-modulated radiotherapy (IMRT) technique capable of acquiring projection images during treatment. Treatment plans for lung tumors using stereotactic body radiotherapy (SBRT) are calculated with planning computed tomography (CT) images only exhale phase. Purpose of this study is to evaluate dose distribution by reconstructing from only the data such as respiratory signals and machine parameters acquired during treatment. Methods: Phantom and three patients with lung tumor underwent CT scans for treatment planning. They were treated by VMAT while acquiring projection images to derive their respiratory signals and machine parameters including positions ofmore » multi leaf collimators, dose rates and integrated monitor units. The respiratory signals were divided into 4 and 10 phases and machine parameters were correlated with the divided respiratory signals based on the gantry angle. Dose distributions of each respiratory phase were calculated from plans which were reconstructed from the respiratory signals and the machine parameters during treatment. The doses at isocenter, maximum point and the centroid of target were evaluated. Results and Discussion: Dose distributions during treatment were calculated using the machine parameters and the respiratory signals detected from projection images. Maximum dose difference between plan and in treatment distribution was −1.8±0.4% at centroid of target and dose differences of evaluated points between 4 and 10 phases were no significant. Conclusion: The present method successfully evaluated dose distribution using respiratory signals and machine parameters during treatment. This method is feasible to verify the actual dose for moving target.« less

High dose-per-pulse electron beam dosimetry: Usability and dose-rate independence of EBT3 Gafchromic films.

PubMed

Jaccard, Maud; Petersson, Kristoffer; Buchillier, Thierry; Germond, Jean-François; Durán, Maria Teresa; Vozenin, Marie-Catherine; Bourhis, Jean; Bochud, François O; Bailat, Claude

2017-02-01

The aim of this study was to assess the suitability of Gafchromic EBT3 films for reference dose measurements in the beam of a prototype high dose-per-pulse linear accelerator (linac), capable of delivering electron beams with a mean dose-rate (Ḋ m ) ranging from 0.07 to 3000 Gy/s and a dose-rate in pulse (Ḋ p ) of up to 8 × 10 6 Gy/s. To do this, we evaluated the overall uncertainties in EBT3 film dosimetry as well as the energy and dose-rate dependence of their response. Our dosimetric system was composed of EBT3 Gafchromic films in combination with a flatbed scanner and was calibrated against an ionization chamber traceable to primary standard. All sources of uncertainties in EBT3 dosimetry were carefully analyzed using irradiations at a clinical radiotherapy linac. Energy dependence was investigated with the same machine by acquiring and comparing calibration curves for three different beam energies (4, 8 and 12 MeV), for doses between 0.25 and 30 Gy. Ḋ m dependence was studied at the clinical linac by changing the pulse repetition frequency (f) of the beam in order to vary Ḋ m between 0.55 and 4.40 Gy/min, while Ḋ p dependence was probed at the prototype machine for Ḋ p ranging from 7 × 10 3 to 8 × 10 6 Gy/s. Ḋ p dependence was first determined by studying the correlation between the dose measured by films and the charge of electrons measured at the exit of the machine by an induction torus. Furthermore, we compared doses from the films to independently calibrated thermo-luminescent dosimeters (TLD) that have been reported as being dose-rate independent up to such high dose-rates. We report that uncertainty below 4% (k = 2) can be achieved in the dose range between 3 and 17 Gy. Results also demonstrated that EBT3 films did not display any detectable energy dependence for electron beam energies between 4 and 12 MeV. No Ḋ m dependence was found either. In addition, we obtained excellent consistency between films and TLDs over the entire Ḋ p range attainable at the prototype linac confirming the absence of any dose-rate dependence within the investigated range (7 × 10 3 to 8 × 10 6 Gy/s). This aspect was further corroborated by the linear relationship between the dose-per-pulse (D p ) measured by films and the charge per pulse (C p ) measured at the prototype linac exit. Our study shows that the use of EBT3 Gafchromic films can be extended to reference dosimetry in pulsed electron beams with a very high dose rate. The measurement results are associated with an overall uncertainty below 4% (k = 2) and are dose-rate and energy independent. © 2016 American Association of Physicists in Medicine.

Effect of infusion regime on doxorubicin pharmacokinetics in the cat.

PubMed

Hahn, K A; Frazier, D L; Cox, S K; Legendre, A M

1997-01-01

In the pharmacokinetic evaluation of a single doxorubicin dose calculated by body surface area (25 mg/m2) or body weight (1 mg/kg body weight) and given intravenously as a 10-, 15-, or 20-minute infusion, the rate of doxorubicin infusion (mg per minute per m2 or mg per minute per kg) correlated positively with clearance and the distribution rate constant alpha, and it inversely correlated with area under the plasma concentration versus time curve (AUC). These findings suggest that a slower infusion rate results in a greater AUC and longer distribution phase than a faster infusion rate and indicates the importance of normalizing dosage regimes by infusion rate rather than by infusion duration when considering dose-response phenomena in veterinary patients.

Shaken baby syndrome and a triple-dose strategy for its prevention.

PubMed

Stewart, Tanya Charyk; Polgar, Denise; Gilliland, Jason; Tanner, David A; Girotti, Murray J; Parry, Neil; Fraser, Douglas D

2011-12-01

Inflicted traumatic brain injury associated with Shaken Baby Syndrome (SBS) is a leading cause of injury mortality and morbidity in infants. A triple-dose SBS prevention program was implemented with the aim to reduce the incidence of SBS. The objectives of this study were to describe the epidemiology of SBS, the triple-dose prevention program, and its evaluation. Descriptive and spatial epidemiologic profiles of SBS cases treated at Children's Hospital, London Health Sciences Centre, from 1991 to 2010 were created. Dose 1 (in-hospital education): pre-post impact evaluation of registered nurse training, with a questionnaire developed to assess parents' satisfaction with the program. Dose 2 (public health home visits): process evaluation of additional education given to new parents. Dose 3 (media campaign): a questionnaire developed to rate the importance of factors on a 7-point Likert scale. These factors were used to create weights for statistical modeling and mapping within a geographic information system to target prevention ads. Forty-three percent of severe infant injuries were intentional. A total of 54 SBS cases were identified. The mean age was 6.7 months (standard deviation, 10.9 months), with 61% of infant males. The mean Injury Severity Score was 26.3 (standard deviation, 5.5) with a 19% mortality rate. Registered nurses learned new information on crying patterns and SBS, with a 47% increase in knowledge posttraining (p < 0.001). Over 10,000 parents were educated in-hospital, a 93% education compliance rate. Nearly all parents (93%) rated the program as useful, citing "what to do when the crying becomes frustrating" as the most important message. Only 6% of families needed to be educated during home visits. Locations of families with a new baby, high population density, and percentage of lone parents were found to be the most important factors for selecting media sites. The spatial analysis revealed six areas needed to be targeted for ad locations. SBS is a devastating intentional injury that often results in poor outcomes for the child. Implementing a triple-dose prevention program that provides education on crying patterns, coping strategies, and the dangers of shaking is key to SBS prevention. The program increased knowledge. Parents rated the program as useful. The media campaign allowed us to extend the primary prevention beyond new parents to help create a cultural change in the way crying, the primary trigger for SBS, is viewed. Targeting our intervention increased the likelihood that our message was reaching the population in greatest need.

Assessment of normal tissue complications following prostate cancer irradiation: Comparison of radiation treatment modalities using NTCP models

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

Takam, Rungdham; Bezak, Eva; Yeoh, Eric E.

2010-09-15

Purpose: Normal tissue complication probability (NTCP) of the rectum, bladder, urethra, and femoral heads following several techniques for radiation treatment of prostate cancer were evaluated applying the relative seriality and Lyman models. Methods: Model parameters from literature were used in this evaluation. The treatment techniques included external (standard fractionated, hypofractionated, and dose-escalated) three-dimensional conformal radiotherapy (3D-CRT), low-dose-rate (LDR) brachytherapy (I-125 seeds), and high-dose-rate (HDR) brachytherapy (Ir-192 source). Dose-volume histograms (DVHs) of the rectum, bladder, and urethra retrieved from corresponding treatment planning systems were converted to biological effective dose-based and equivalent dose-based DVHs, respectively, in order to account for differences inmore » radiation treatment modality and fractionation schedule. Results: Results indicated that with hypofractionated 3D-CRT (20 fractions of 2.75 Gy/fraction delivered five times/week to total dose of 55 Gy), NTCP of the rectum, bladder, and urethra were less than those for standard fractionated 3D-CRT using a four-field technique (32 fractions of 2 Gy/fraction delivered five times/week to total dose of 64 Gy) and dose-escalated 3D-CRT. Rectal and bladder NTCPs (5.2% and 6.6%, respectively) following the dose-escalated four-field 3D-CRT (2 Gy/fraction to total dose of 74 Gy) were the highest among analyzed treatment techniques. The average NTCP for the rectum and urethra were 0.6% and 24.7% for LDR-BT and 0.5% and 11.2% for HDR-BT. Conclusions: Although brachytherapy techniques resulted in delivering larger equivalent doses to normal tissues, the corresponding NTCPs were lower than those of external beam techniques other than the urethra because of much smaller volumes irradiated to higher doses. Among analyzed normal tissues, the femoral heads were found to have the lowest probability of complications as most of their volume was irradiated to lower equivalent doses compared to other tissues.« less

Safety and long-term humoral immune response in adults after vaccination with an H1N1 2009 pandemic influenza vaccine with or without AS03 adjuvant.

PubMed

Ferguson, Murdo; Risi, George; Davis, Matthew; Sheldon, Eric; Baron, Mira; Li, Ping; Madariaga, Miguel; Fries, Louis; Godeaux, Olivier; Vaughn, David

2012-03-01

In this study (NCT00985088) we evaluated different formulations of an H1N1 2009 pandemic influenza vaccine that deliver various viral hemagglutinin (HA) doses with or without AS03 (a tocopherol-based oil-in-water adjuvant system). A total of 1340 healthy subjects aged ≥18 years were randomized to receive 1 or 2 doses of an adjuvanted (3.75-μg HA/AS03(A) or 1.9-μg HA/AS03(B)) or nonadjuvanted vaccine formulation. Safety and immunogenicity (by hemagglutination-inhibition [HI] assay) after each dose and 6 months after dose 1 are reported here. A single dose of AS03(A)-adjuvanted 3.75-μg HA H1N1 2009 induced the strongest immune responses in subjects aged 18-64 years (seroprotection rate [SPR], 97.2%; seroconversion rate [SCR], 90.1%) as well as in subjects aged >64 years (SPR, 91.1%; SCR, 78.2%) 21 days after vaccination. Six months after dose 1, subjects who received 2 doses of either the adjuvanted formulation or 1 dose of the adjuvanted 3.75-μg HA formulation continued to meet all Center for Biologics Evaluation and Research and Committee for Medicinal Products for Human Use criteria. All formulations had clinically acceptable safety profiles. A single dose of the 3.75-μg HA AS03(A)-adjuvanted H1N1 2009 influenza vaccine was highly immunogenic in both age strata (18-64 and >64 years), inducing long-term persistence of the immune response until at least 6 months after dose 1.

Thermoluminescence dosimetry for in-vivo verification of high dose rate brachytherapy for prostate cancer.

PubMed

Das, R; Toye, W; Kron, T; Williams, S; Duchesne, G

2007-09-01

It was the aim of the study to verify dose delivered in urethra and rectum during High Dose Rate brachytherapy boost (HDRBB) of prostate cancer patients. During the first fraction of HDRBB measurement catheters were placed in the urethra and rectum of prostate cancer patients. These contained LiF:Mg,Ti Thermoluminescence Dosimetry (TLD) rods of 1 mm diameter, with up to 11 detectors positioned every 16 mm separated by radio-opaque markers. A Lorentzian peak function was used to fit the data. Measurements from 50 patients were evaluated and measured doses were compared with predictions from the treatment planning system (Plato Vs 13.5 to 14.1). Prospective urinary and rectal toxicity scores were collected following treatment. In more than 90% of cases, the Lorentzian peak function provided a good fit to both experimental and planning urethral data (r2 > 0.9). In general there was good agreement between measured and predicted doses with the average difference between measured and planned maximum dose being 0.1 Gy. No significant association between dose and any clinical endpoints was observed in 43 patients available for clinical evaluation. An average inferior shift of 2 mm between the plan and the measurement performed approximately 1 hour after the planning CT scan was found for the dose distribution in the cohort of patients for the urethra measurements. Rectal measurements proved to be more difficult to interpret as there is more variability of TLD position between planning and treatment. TLD in-vivo measurements are easily performed in urethra and rectum during HDR brachytherapy of prostate patients. They verify the delivery and provide information about the dose delivered to critical structures. The latter may be of particular interest if higher doses are to be given per fraction such as in HDR monotherapy.

Comparison of 2D and 3D Imaging and Treatment Planning for Postoperative Vaginal Apex High-Dose Rate Brachytherapy for Endometrial Cancer

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

Russo, James K.; Armeson, Kent E.; Richardson, Susan, E-mail: srichardson@radonc.wustl.edu

2012-05-01

Purpose: To evaluate bladder and rectal doses using two-dimensional (2D) and 3D treatment planning for vaginal cuff high-dose rate (HDR) in endometrial cancer. Methods and Materials: Ninety-one consecutive patients treated between 2000 and 2007 were evaluated. Seventy-one and 20 patients underwent 2D and 3D planning, respectively. Each patient received six fractions prescribed at 0.5 cm to the superior 3 cm of the vagina. International Commission on Radiation Units and Measurements (ICRU) doses were calculated for 2D patients. Maximum and 2-cc doses were calculated for 3D patients. Organ doses were normalized to prescription dose. Results: Bladder maximum doses were 178% ofmore » ICRU doses (p < 0.0001). Two-cubic centimeter doses were no different than ICRU doses (p = 0.22). Two-cubic centimeter doses were 59% of maximum doses (p < 0.0001). Rectal maximum doses were 137% of ICRU doses (p < 0.0001). Two-cubic centimeter doses were 87% of ICRU doses (p < 0.0001). Two-cubic centimeter doses were 64% of maximum doses (p < 0.0001). Using the first 1, 2, 3, 4 or 5 fractions, we predicted the final bladder dose to within 10% for 44%, 59%, 83%, 82%, and 89% of patients by using the ICRU dose, and for 45%, 55%, 80%, 85%, and 85% of patients by using the maximum dose, and for 37%, 68%, 79%, 79%, and 84% of patients by using the 2-cc dose. Using the first 1, 2, 3, 4 or 5 fractions, we predicted the final rectal dose to within 10% for 100%, 100%, 100%, 100%, and 100% of patients by using the ICRU dose, and for 60%, 65%, 70%, 75%, and 75% of patients by using the maximum dose, and for 68%, 95%, 84%, 84%, and 84% of patients by using the 2-cc dose. Conclusions: Doses to organs at risk vary depending on the calculation method. In some cases, final dose accuracy appears to plateau after the third fraction, indicating that simulation and planning may not be necessary in all fractions. A clinically relevant level of accuracy should be determined and further research conducted to address this issue.« less

Evaluation of ifosfamide salvage therapy for metastatic canine osteosarcoma.

PubMed

Batschinski, K; Dervisis, N G; Kitchell, B E

2014-12-01

A retrospective study was performed to assess toxicity and response rate of ifosfamide salvage treatment for dogs diagnosed with metastatic osteosarcoma (OSA). Dogs diagnosed with OSA and previously treated with standard chemotherapy were included in the study. Nineteen dogs met the inclusion criteria, and 17 dogs were evaluable for response. Ifosfamide doses ranged from 375 to 425 mg m(-2) (median dose 375 mg m(-2)), with a median of two doses administered per dog (range 1-7 doses). The overall response to ifosfamide was 11.8% [complete response (CR) = 1/17, partial response (PR) = 1/17, stable disease (SD) = 2/17, progressive disease (PD) = 13/17]. Two dogs were hospitalized due to ifosfamide toxicosis. The median survival duration from the first dose of ifosfamide to death was 95 days. Ifosfamide was well tolerated, but minor anti-tumour activity was observed. © 2012 Blackwell Publishing Ltd.

SU-F-T-50: Evaluation of Monte Carlo Simulations Performance for Pediatric Brachytherapy Dosimetry

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

Chatzipapas, C; Kagadis, G; Papadimitroulas, P

Purpose: Pediatric tumors are generally treated with multi-modal procedures. Brachytherapy can be used with pediatric tumors, especially given that in this patient population low toxicity on normal tissues is critical as is the suppression of the probability for late malignancies. Our goal is to validate the GATE toolkit on realistic brachytherapy applications, and evaluate brachytherapy plans on pediatrics for accurate dosimetry on sensitive and critical organs of interest. Methods: The GATE Monte Carlo (MC) toolkit was used. Two High Dose Rate (HDR) 192Ir brachytherapy sources were simulated (Nucletron mHDR-v1 and Varian VS2000), and fully validated using the AAPM and ESTROmore » protocols. A realistic brachytherapy plan was also simulated using the XCAT anthropomorphic computational model .The simulated data were compared to the clinical dose points. Finally, a 14 years old girl with vaginal rhabdomyosarcoma was modelled based on clinical procedures for the calculation of the absorbed dose per organ. Results: The MC simulations resulted in accurate dosimetry in terms of dose rate constant (Λ), radial dose gL(r) and anisotropy function F(r,θ) for both sources.The simulations were executed using ∼1010 number of primaries resulting in statistical uncertainties lower than 2%.The differences between the theoretical values and the simulated ones ranged from 0.01% up to 3.3%, with the largest discrepancy (6%) being observed in the dose rate constant calculation.The simulated DVH using an adult female XCAT model was also compared to a clinical one resulting in differences smaller than 5%. Finally, a realistic pediatric brachytherapy simulation was performed to evaluate the absorbed dose per organ and to calculate DVH with respect to heterogeneities of the human anatomy. Conclusion: GATE is a reliable tool for brachytherapy simulations both for source modeling and for dosimetry in anthropomorphic voxelized models. Our project aims to evaluate a variety of pediatric brachytherapy schemes using a population of pediatric phantoms for several pathological cases. This study is part of a project that has received funding from the European Union Horizon2020 research and innovation programme under the MarieSklodowska-Curiegrantagreement.No691203.The results published in this study reflect only the authors view and the Research Executive Agency (REA) and the European Commission is not responsible for any use that may be madeof the information it contains.« less

Design and implementation of wireless dose logger network for radiological emergency decision support system.

PubMed

Gopalakrishnan, V; Baskaran, R; Venkatraman, B

2016-08-01

A decision support system (DSS) is implemented in Radiological Safety Division, Indira Gandhi Centre for Atomic Research for providing guidance for emergency decision making in case of an inadvertent nuclear accident. Real time gamma dose rate measurement around the stack is used for estimating the radioactive release rate (source term) by using inverse calculation. Wireless gamma dose logging network is designed, implemented, and installed around the Madras Atomic Power Station reactor stack to continuously acquire the environmental gamma dose rate and the details are presented in the paper. The network uses XBee-Pro wireless modules and PSoC controller for wireless interfacing, and the data are logged at the base station. A LabView based program is developed to receive the data, display it on the Google Map, plot the data over the time scale, and register the data in a file to share with DSS software. The DSS at the base station evaluates the real time source term to assess radiation impact.

Design and implementation of wireless dose logger network for radiological emergency decision support system

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

Gopalakrishnan, V.; Baskaran, R.; Venkatraman, B.

A decision support system (DSS) is implemented in Radiological Safety Division, Indira Gandhi Centre for Atomic Research for providing guidance for emergency decision making in case of an inadvertent nuclear accident. Real time gamma dose rate measurement around the stack is used for estimating the radioactive release rate (source term) by using inverse calculation. Wireless gamma dose logging network is designed, implemented, and installed around the Madras Atomic Power Station reactor stack to continuously acquire the environmental gamma dose rate and the details are presented in the paper. The network uses XBee–Pro wireless modules and PSoC controller for wireless interfacing,more » and the data are logged at the base station. A LabView based program is developed to receive the data, display it on the Google Map, plot the data over the time scale, and register the data in a file to share with DSS software. The DSS at the base station evaluates the real time source term to assess radiation impact.« less

MO-FG-BRA-05: Dosimetric and Radiobiological Validation of Respiratory Gating in Conventional and Hypofractionated Radiotherapy of the Lung: Effect of Dose, Dose Rate, Gating Window and Breathing Pattern

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

Cervino, L; Soultan, D; Pettersson, N

2016-06-15

Purpose: to evaluate the dosimetric and radiobiological consequences from having different gating windows, dose rates, and breathing patterns in gated VMAT lung radiotherapy. Methods: A novel 3D-printed moving phantom with central high and peripheral low tracer uptake regions was 4D FDG-PET/CT-scanned using ideal, patient-specific regular, and irregular breathing patterns. A scan of the stationary phantom was obtained as a reference. Target volumes corresponding to different uptake regions were delineated. Simultaneous integrated boost (SIB) 6 MV VMAT plans were produced for conventional and hypofractionated radiotherapy, using 30–70 and 100% cycle gating scenarios. Prescribed doses were 200 cGy with SIB to 240more » cGy to high uptake volume for conventional, and 800 with SIB to 900 cGy for hypofractionated plans. Dose rates of 600 MU/min (conventional and hypofractionated) and flattening filter free 1400 MU/min (hypofractionated) were used. Ion chamber measurements were performed to verify delivered doses. Vials with A549 cells placed in locations matching ion chamber measurements were irradiated using the same plans to measure clonogenic survival. Differences in survival for the different doses, dose rates, gating windows, and breathing patterns were analyzed. Results: Ion chamber measurements agreed within 3% of the planned dose, for all locations, breathing patterns and gating windows. Cell survival depended on dose alone, and not on gating window, breathing pattern, MU rate, or delivery time. The surviving fraction varied from approximately 40% at 2Gy to 1% for 9 Gy and was within statistical uncertainty relative to that observed for the stationary phantom. Conclusions: Use of gated VMAT in PET-driven SIB radiotherapy was validated using ion chamber measurements and cell survival assays for conventional and hypofractionated radiotherapy.« less

Evaluating the accuracy of technicians and pharmacists in checking unit dose medication cassettes.

PubMed

Ambrose, Peter J; Saya, Frank G; Lovett, Larry T; Tan, Sandy; Adams, Dale W; Shane, Rita

2002-06-15

The accuracy rates of board-registered pharmacy technicians and pharmacists in checking unit dose medication cassettes in the inpatient setting at two separate institutions were examined. Cedars-Sinai Medical Center and Long Beach Memorial Medical Center, both in Los Angeles county, petitioned the California State Board of Pharmacy to approve a waiver of the California Code of Regulations to conduct an experimental program to compare the accuracy of unit dose medication cassettes checked by pharmacists with that of cassettes checked by trained, certified pharmacy technicians. The study consisted of three parts: assessing pharmacist baseline checking accuracy (Phase I), developing a technician-training program and certifying technicians who completed the didactic and practical training (Phase II), and evaluating the accuracy of certified technicians checking unit dose medication cassettes as a daily function (Phase III). Twenty-nine pharmacists and 41 technicians (3 of whom were pharmacy interns) participated in the study. Of the technicians, all 41 successfully completed the didactic and practical training, 39 successfully completed the audits and became certified checkers, and 2 (including 1 of the interns) did not complete the certification audits because they were reassigned to another work area or had resigned. In Phase II, the observed accuracy rate and its lower confidence limit exceeded the predetermined minimum requirement of 99.8% for a certified checker. The mean accuracy rates for technicians were identical at the two institutions (p = 1.0). The difference in mean accuracy rates between pharmacists (99.52%; 95% confidence interval [CI] 99.44-99.58%) and technicians, (99.89%; 95% CI 99.87-99.90%) was significant (p < 0.0001). Inpatient technicians who had been trained and certified in a closely supervised program that incorporated quality assurance mechanisms could safely and accurately check unit dose medication cassettes filled by other technicians.

Reducing the dose of smallpox vaccine reduces vaccine-associated morbidity without reducing vaccination success rates or immune responses.

PubMed

Couch, Robert B; Winokur, Patricia; Edwards, Kathryn M; Black, Steven; Atmar, Robert L; Stapleton, Jack T; Kissner, Jennifer M; Shinefield, Henry; Denny, Thomas N; Bybel, Michael J; Newman, Frances K; Yan, Lihan

2007-03-15

When the decision was made to prepare for a deliberate release of smallpox, the United States had approximately 15 million doses of Wyeth Dryvax vaccine, which was known to induce significant morbidity when used undiluted; Sanofi Pasteur, Inc., later identified approximately 85 million additional doses in storage. Eleven vaccine-dose groups, each with 30 vaccinia-naive subjects, were given diluted Dryvax vaccine or 1 of 2 lots of Sanofi Pasteur smallpox vaccine and were evaluated for vaccination success rates, morbidity, and immune responses. Estimated doses of 10(6.6)-10(8.2) pfu of virus/mL induced major reactions (or "takes") in 93%-100% of subjects in each dose group. No differences in vaccination take rates, lesion size, erythema, and induration or in serum neutralizing-antibody response were detected between the groups. However, systemic reactogenicity and missed activities were significantly lower for the vaccine groups given doses of 10(6.6)-10(7.2) pfu/mL than for those given doses of 10(7.6)-10(8.2) pfu/mL. These findings support the use of a higher dilution of Wyeth Dryvax vaccine and Sanofi Pasteur smallpox vaccine, given that the resulting morbidity should be significantly lower without loss of vaccine effectiveness. A plan for use of higher dilutions would create an enormous stockpile of vaccine.

Sperm Oxidative Stress Is Detrimental to Embryo Development: A Dose-Dependent Study Model and a New and More Sensitive Oxidative Status Evaluation

PubMed Central

de Castro, Letícia S.; de Assis, Patrícia M.; Siqueira, Adriano F. P.; Hamilton, Thais R. S.; Mendes, Camilla M.; Losano, João D. A.; Nichi, Marcílio; Visintin, José A.; Assumpção, Mayra E. O. A.

2016-01-01

Our study aimed to assess the impact of sperm oxidative stress on embryo development by means of a dose-dependent model. In experiment 1, straws from five bulls were subjected to incubation with increasing H2O2 doses (0, 12.5, 25, and 50 μM). Motility parameters were evaluated by Computed Assisted System Analysis (CASA). Experiment 2 was designed to study a high (50 μM) and low dose (12.5 μM) of H2O2 compared to a control (0 μM). Samples were incubated and further used for in vitro fertilization. Analyses of motility (CASA), oxidative status (CellROX green and 2'-7' dichlorofluorescein diacetate), mitochondrial potential (JC-1), chromatin integrity (AO), and sperm capacitation status (chlortetracycline) were performed. Embryos were evaluated based on fast cleavage (30 h.p.i.), cleavage (D = 3), development (D = 5), and blastocyst rates (D = 8). We observed a dose-dependent deleterious effect of H2O2 on motility and increase on the percentages of positive cells for CellROX green, capacitated sperm, and AO. A decrease on cleavage and blastocyst rates was observed as H2O2 increased. Also, we detected a blockage on embryo development. We concluded that sperm when exposed to oxidative environment presents impaired motility traits, prooxidative status, and premature capacitation; such alterations resulting in embryo development fail. PMID:26770658

SU-F-BRD-04: Robustness Analysis of Proton Breast Treatments Using An Alpha-Stable Distribution Parameterization

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

Van den Heuvel, F; Hackett, S; Fiorini, F

Purpose: Currently, planning systems allow robustness calculations to be performed, but a generalized assessment methodology is not yet available. We introduce and evaluate a methodology to quantify the robustness of a plan on an individual patient basis. Methods: We introduce the notion of characterizing a treatment instance (i.e. one single fraction delivery) by describing the dose distribution within an organ as an alpha-stable distribution. The parameters of the distribution (shape(α), scale(γ), position(δ), and symmetry(β)), will vary continuously (in a mathematical sense) as the distributions change with the different positions. The rate of change of the parameters provides a measure ofmore » the robustness of the treatment. The methodology is tested in a planning study of 25 patients with known residual errors at each fraction. Each patient was planned using Eclipse with an IBA-proton beam model. The residual error space for every patient was sampled 30 times, yielding 31 treatment plans for each patient and dose distributions in 5 organs. The parameters’ change rate as a function of Euclidean distance from the original plan was analyzed. Results: More than 1,000 dose distributions were analyzed. For 4 of the 25 patients the change in scale rate (γ) was considerably higher than the lowest change rate, indicating a lack of robustness. The sign of the shape change rate (α) also seemed indicative but the experiment lacked the power to prove significance. Conclusion: There are indications that this robustness measure is a valuable tool to allow a more patient individualized approach to the determination of margins. In a further study we will also evaluate this robustness measure using photon treatments, and evaluate the impact of using breath hold techniques, and the a Monte Carlo based dose deposition calculation. A principle component analysis is also planned.« less

Sperm quality and fertility of boar seminal doses after 2 days of storage: does the type of extender really matter?

PubMed

Pinart, Elisabeth; Yeste, Marc; Prieto-Martínez, Noelia; Reixach, Josep; Bonet, Sergi

2015-06-01

The present approach was designed to evaluate the extender effects on sperm quality and fertility of short-term refrigerated seminal doses from Landrace boars lodged in husbandry-controlled conditions. For this purpose, we analyzed the sperm quality of seminal doses diluted in short-term (Beltsville Thawing Solution) and extra-long-term (Duragen) extenders from Days 0 to 2 of storage at 17 °C during an 8-month period. Pregnancy rates and litter size were evaluated from double inseminations within an interval of 12 hours (36 and 48 hours of refrigeration) of multiparous females using seminal doses diluted in each extender type. Sperm quality was assessed from the analyses of sperm motility and kinetics, sperm viability, expressed as plasma and acrosome membrane integrity, membrane lipid disorder, intracellular calcium levels, and acrosin activity. Results indicated significant differences between the extenders in the sperm quality of seminal doses. Therefore, the seminal doses diluted in Duragen had higher percentages of progressive motile spermatozoa and membrane-intact spermatozoa than those diluted in Beltsville Thawing Solution throughout all the experimental months. Nevertheless, despite these differences in preserving the sperm quality, pregnancy rates (>90%) and litter sizes (>10 piglets born per litter) were similar between the extenders. Our results had great relevance from a practical point of view because they reported lack of an extender effect on the reproductive performance of seminal doses during short-tem storage. Copyright © 2015 Elsevier Inc. All rights reserved.

Comparison of TID Effects in Space-Like Variable Dose Rates and Constant Dose Rates

NASA Technical Reports Server (NTRS)

Harris, Richard D.; McClure, Steven S.; Rax, Bernard G.; Evans, Robin W.; Jun, Insoo

2008-01-01

The degradation of the LM193 dual voltage comparator has been studied at different TID dose rate profiles, including several different constant dose rates and a variable dose rate that simulates the behavior of a solar flare. A comparison of results following constant dose rate vs. variable dose rates is made to explore how well the constant dose rates used for typical part testing predict the performance during a simulated space-like mission. Testing at a constant dose rate equal to the lowest dose rate seen during the simulated flare provides an extremely conservative estimate of the overall amount of degradation. A constant dose rate equal to the average dose rate is also more conservative than the variable rate. It appears that, for this part, weighting the dose rates by the amount of total dose received at each rate (rather than the amount of time at each dose rate) results in an average rate that produces an amount of degradation that is a reasonable approximation to that received by the variable rate.

Atmospheric radiation modeling of galactic cosmic rays using LRO/CRaTER and the EMMREM model with comparisons to balloon and airline based measurements

NASA Astrophysics Data System (ADS)

Joyce, C. J.; Schwadron, N. A.; Townsend, L. W.; deWet, W. C.; Wilson, J. K.; Spence, H. E.; Tobiska, W. K.; Shelton-Mur, K.; Yarborough, A.; Harvey, J.; Herbst, A.; Koske-Phillips, A.; Molina, F.; Omondi, S.; Reid, C.; Reid, D.; Shultz, J.; Stephenson, B.; McDevitt, M.; Phillips, T.

2016-09-01

We provide an analysis of the galactic cosmic ray radiation environment of Earth's atmosphere using measurements from the Cosmic Ray Telescope for the Effects of Radiation (CRaTER) aboard the Lunar Reconnaissance Orbiter (LRO) together with the Badhwar-O'Neil model and dose lookup tables generated by the Earth-Moon-Mars Radiation Environment Module (EMMREM). This study demonstrates an updated atmospheric radiation model that uses new dose tables to improve the accuracy of the modeled dose rates. Additionally, a method for computing geomagnetic cutoffs is incorporated into the model in order to account for location-dependent effects of the magnetosphere. Newly available measurements of atmospheric dose rates from instruments aboard commercial aircraft and high-altitude balloons enable us to evaluate the accuracy of the model in computing atmospheric dose rates. When compared to the available observations, the model seems to be reasonably accurate in modeling atmospheric radiation levels, overestimating airline dose rates by an average of 20%, which falls within the uncertainty limit recommended by the International Commission on Radiation Units and Measurements (ICRU). Additionally, measurements made aboard high-altitude balloons during simultaneous launches from New Hampshire and California provide an additional comparison to the model. We also find that the newly incorporated geomagnetic cutoff method enables the model to represent radiation variability as a function of location with sufficient accuracy.

Technical Note: The impact of deformable image registration methods on dose warping.

PubMed

Qin, An; Liang, Jian; Han, Xiao; O'Connell, Nicolette; Yan, Di

2018-03-01

The purpose of this study was to investigate the clinical-relevant discrepancy between doses warped by pure image based deformable image registration (IM-DIR) and by biomechanical model based DIR (BM-DIR) on intensity-homogeneous organs. Ten patients (5Head&Neck, 5Prostate) were included. A research DIR tool (ADMRIE_v1.12) was utilized for IM-DIR. After IM-DIR, BM-DIR was carried out for organs (parotids, bladder, and rectum) which often encompass sharp dose gradient. Briefly, high-quality tetrahedron meshes were generated and deformable vector fields (DVF) from IM-DIR were interpolated to the surface nodes of the volume meshes as boundary condition. Then, a FEM solver (ABAQUS_v6.14) was used to simulate the displacement of internal nodes, which were then interpolated to image-voxel grids to get the more physically plausible DVF. Both geometrical and subsequent dose warping discrepancies were quantified between the two DIR methods. Target registration discrepancy(TRD) was evaluated to show the geometry difference. The re-calculated doses on second CT were warped to the pre-treatment CT via two DIR. Clinical-relevant dose parameters and γ passing rate were compared between two types of warped dose. The correlation was evaluated between parotid shrinkage and TRD/dose discrepancy. The parotid shrunk to 75.7% ± 9% of its pre-treatment volume and the percentage of volume with TRD>1.5 mm) was 6.5% ± 4.7%. The normalized mean-dose difference (NMDD) of IM-DIR and BM-DIR was -0.8% ± 1.5%, with range (-4.7% to 1.5%). 2 mm/2% passing rate was 99.0% ± 1.4%. A moderate correlation was found between parotid shrinkage and TRD and NMDD. The bladder had a NMDD of -9.9% ± 9.7%, with BM-DIR warped dose systematically higher. Only minor deviation was observed for rectum NMDD (0.5% ± 1.1%). Impact of DIR method on treatment dose warping is patient and organ-specific. Generally, intensity-homogeneous organs, which undergo larger deformation/shrinkage during treatment and encompass sharp dose gradient, will have greater dose warping uncertainty. For these organs, BM-DIR could be beneficial to the evaluation of DIR/dose-warping uncertainty. © 2018 American Association of Physicists in Medicine.

An algorithm for treatment of patients with hypersensitivity reactions after vaccines.

PubMed

Wood, Robert A; Berger, Melvin; Dreskin, Stephen C; Setse, Rosanna; Engler, Renata J M; Dekker, Cornelia L; Halsey, Neal A

2008-09-01

Concerns about possible allergic reactions to immunizations are raised frequently by both patients/parents and primary care providers. Estimates of true allergic, or immediate hypersensitivity, reactions to routine vaccines range from 1 per 50000 doses for diphtheria-tetanus-pertussis to approximately 1 per 500000 to 1000000 doses for most other vaccines. In a large study from New Zealand, data were collected during a 5-year period on 15 marketed vaccines and revealed an estimated rate of 1 immediate hypersensitivity reaction per 450000 doses of vaccine administered. Another large study, conducted within the Vaccine Safety Datalink, described a range of reaction rates to >7.5 million doses. Depending on the study design and the time after the immunization event, reaction rates varied from 0.65 cases per million doses to 1.53 cases per million doses when additional allergy codes were included. For some vaccines, particularly when allergens such as gelatin are part of the formulation (eg, Japanese encephalitis), higher rates of serious allergic reactions may occur. Although these per-dose estimates suggest that true hypersensitivity reactions are quite rare, the large number of doses that are administered, especially for the commonly used vaccines, makes this a relatively common clinical problem. In this review, we present background information on vaccine hypersensitivity, followed by a detailed algorithm that provides a rational and organized approach for the evaluation and treatment of patients with suspected hypersensitivity. We then include 3 cases of suspected allergic reactions to vaccines that have been referred to the Clinical Immunization Safety Assessment network to demonstrate the practical application of the algorithm.

[Immune response to one booster dose of inactivated hepatitis A vaccine in college students].

PubMed

Liao, Z; Feng, X W; Liu, X E; Zhou, Y S; Wen, H R; Peng, S H; Zhang, Y X; Xu, B; Zhuang, H; Chen, H Y

2017-05-10

Objective: To evaluate the safety and immunogenicity of one booster dose of inactivated hepatitis A vaccine in young adults. Methods: The subjects were selected from participants in the clinical trial of immunogenicity of inactivated and attenuated live hepatitis A vaccine in young adults. Eligible subjects were those who had received one dose of inactivated or attenuated hepatitis A vaccine, could be contacted and were sero-negative before primary vaccination. All qualified subjects were immunized with one booster dose of inactivated hepatitis A vaccine. The blood samples were collected before booster dose vaccination and 28 days after the immunization. Anti-HAV antibody titer ≥20 mIU/ml was considered to be sero-protected against hepatitis A virus. Results: The GMCs in the inactivated HAV vaccine group and attenuated live vaccine group before booster dose vaccination were 70.80 mIU/ml and 50.12 mIU/ml, respectively, and the sero-protection rates were 94.7 % and 65.0 % , respectively. After the vaccination of the booster dose, the sero-protection rates in both groups were 100.0 % , and the GMCs were 2 816.09 mIU/ml and 2 654.55 mIU/ml, respectively. Conclusion: The GMCs and sero-protection rates of anti-HAV antibody in young adults declined after three years of the primary vaccination. However, the higher GMC and sero-protection rate were observed in the inactivated vaccine group than in the attenuated live vaccine group. Significant increases of GMC levels were observed in both groups after one booster dose vaccination.

SU-E-T-315: The Change of Optically Stimulated Luminescent Dosimeters (OSLDs) Sensitivity by Accumulated Dose and High Dose

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

Han, S; Jung, H; Kim, M

2014-06-01

Purpose: The objective of this study is to evaluate radiation sensitivity of optical stimulated luminance dosimeters (OSLDs) by accumulated dose and high dose. Methods: This study was carried out in Co-60 unit (Theratron 780, AECL, and Canada) and used InLight MicroStar reader (Landauer, Inc., Glenwood, IL) for reading. We annealed for 30 min using optical annealing system which contained fluorescent lamps (Osram lumilux, 24 W, 280 ∼780 nm). To evaluate change of OSLDs sensitivity by repeated irradiation, the dosimeters were repeatedly irradiated with 1 Gy. And whenever a repeated irradiation, we evaluated OSLDs sensitivity. To evaluate OSLDs sensitivity after accumulatedmore » dose with 5 Gy, We irradiated dose accumulatively (from 1 Gy to 5 Gy) without annealing. And OSLDs was also irradiated with 15, 20, 30 Gy to certify change of OSLDs sensitivity after high dose irradiation. After annealing them, they were irradiated with 1Gy, repeatedly. Results: The OSLDs sensitivity increased up to 3% during irradiating seven times and decreased continuously above 8 times. That dropped by about 0.35 Gy per an irradiation. Finally, after 30 times irradiation, OSLDs sensitivity decreased by about 7%. For accumulated dose from 1 Gy to 5 Gy, OSLDs sensitivity about 1 Gy increased until 4.4% after second times accumulated dose compared with before that. OSLDs sensitivity about 1 Gy decreased by 1.6% in five times irradiation. When OSLDs were irradiated ten times with 1Gy after irradiating high dose (10, 15, 20 Gy), OSLDs sensitivity decreased until 6%, 9%, 12% compared with it before high dose irradiation, respectively. Conclusion: This study certified OSLDs sensitivity by accumulated dose and high dose. When irradiated with 1Gy, repeatedly, OSLDs sensitivity decreased linearly and the reduction rate of OSLDs sensitivity after high dose irradiation had dependence on irradiated dose.« less

Dosimetric characterization of a microDiamond detector in clinical scanned carbon ion beams.

PubMed

Marinelli, Marco; Prestopino, G; Verona, C; Verona-Rinati, G; Ciocca, M; Mirandola, A; Mairani, A; Raffaele, L; Magro, G

2015-04-01

To investigate for the first time the dosimetric properties of a new commercial synthetic diamond detector (PTW microDiamond) in high-energy scanned clinical carbon ion beams generated by a synchrotron at the CNAO facility. The detector response was evaluated in a water phantom with actively scanned carbon ion beams ranging from 115 to 380 MeV/u (30-250 mm Bragg peak depth in water). Homogeneous square fields of 3 × 3 and 6 × 6 cm(2) were used. Short- and medium-term (2 months) detector response stability, dependence on beam energy as well as ion type (carbon ions and protons), linearity with dose, and directional and dose-rate dependence were investigated. The depth dose curve of a 280 MeV/u carbon ion beam, scanned over a 3 × 3 cm(2) area, was measured with the microDiamond detector and compared to that measured using a PTW Advanced Markus ionization chamber, and also simulated using fluka Monte Carlo code. The detector response in two spread-out-Bragg-peaks (SOBPs), respectively, centered at 9 and 21 cm depths in water and calculated using the treatment planning system (TPS) used at CNAO, was measured. A negligible drift of detector sensitivity within the experimental session was seen, indicating that no detector preirradiation was needed. Short-term response reproducibility around 1% (1 standard deviation) was found. Only 2% maximum variation of microDiamond sensitivity was observed among all the evaluated proton and carbon ion beam energies. The detector response showed a good linear behavior. Detector sensitivity was found to be dose-rate independent, with a variation below 1.3% in the evaluated dose-rate range. A very good agreement between measured and simulated Bragg curves with both microDiamond and Advanced Markus chamber was found, showing a negligible LET dependence of the tested detector. A depth dose curve was also measured by positioning the microDiamond with its main axis oriented orthogonally to the beam direction. A strong distortion in Bragg peak measurement was observed, confirming manufacturer recommendation on avoiding such configuration. Very good results were obtained for SOBP measurements, with a difference below 1% between measured and TPS-calculated doses. The stability of detector sensitivity in the observation period was within the experimental uncertainty. Dosimetric characterization of a PTW microDiamond detector in high-energy scanned carbon ion beams was performed. The results of the present study showed that this detector is suitable for dosimetry of clinical carbon ion beams, with a negligible LET and dose-rate dependence.

Evaluation of a 15-week CHOP protocol for the treatment of canine multicentric lymphoma.

PubMed

Burton, J H; Garrett-Mayer, E; Thamm, D H

2013-12-01

Dose intense CHOP protocols have been shown to improve outcome for people with non-Hodgkin's lymphoma, but evaluation of dose intense CHOP protocols for canine lymphoma is currently limited. The hypothesis of this retrospective study was that a 15-week dose intense CHOP protocol would have shorter treatment duration with similar efficacy to other doxorubicin-based multidrug protocols. Thirty-one client owned dogs with multicentric lymphoma were treated with a 15-week CHOP chemotherapy protocol with an overall response rate of 100% and a median progression-free interval (PFI) of 140 days [95% confidence interval (CI) 91-335 days]. Dogs that had two or more treatment delays had significantly prolonged PFI and overall survival in multivariate analysis. Dose intensity did not correlate with patient outcome. Dogs experiencing multiple treatment delays secondary to adverse events may receive their individual maximally tolerated dose while dogs with no adverse events may be underdosed. Future studies should focus on individual patient dose optimization. © 2012 Blackwell Publishing Ltd.

Novel, single-dose, topical treatment of tinea pedis using terbinafine: results of a dose-finding clinical trial.

PubMed

de Chauvin, Martine Feuilhade; Viguié-Vallanet, Claude; Kienzler, Jean-Luc; Larnier, Catherine

2008-01-01

Tinea pedis is the most common dermatophytosis requiring topical antifungals for at least 1-4 weeks. To determine the effectiveness of a novel topical single dose formulation of terbinafine (film forming solution-FFS) in the treatment of tinea pedis, 344 outpatients from 43 dermatological centres in France and Bulgaria suffering from tinea pedis with possible extension to soles confirmed by mycological examination (direct and culture) were evaluated for efficacy of terbinafine 1%, 5%, 10% FFS in a randomised double blind vehicle controlled parallel group dose finding study. Evaluations were carried out at baseline, 1 and 6 weeks after a single application of FFS. Effective treatment rate based on negative mycology (direct and culture) and minimal signs and symptoms (two or less with only mild recorded) was measured at week 6. Effective treatment rates at week 6 with terbinafine 1%, 5% and 10% FFS were 66%, 70%, 61% compared with 18% with placebo. All three active preparations were shown to be significantly superior to placebo (P < 0.001). Terbinafine 1% and 5% FFS were shown to be non-inferior to terbinafine 10% FFS. Terbinafine 1% FFS is an effective, safe dose for the treatment of tinea pedis. This novel product represents a significant advance with the enhanced compliance and convenience that it offers.

Efficacy of a radiation absorbing shield in reducing dose to the interventionalist during peripheral endovascular procedures: a single centre pilot study.

PubMed

Power, S; Mirza, M; Thakorlal, A; Ganai, B; Gavagan, L D; Given, M F; Lee, M J

2015-06-01

This prospective pilot study was undertaken to evaluate the feasibility and effectiveness of using a radiation absorbing shield to reduce operator dose from scatter during lower limb endovascular procedures. A commercially available bismuth shield system (RADPAD) was used. Sixty consecutive patients undergoing lower limb angioplasty were included. Thirty procedures were performed without the RADPAD (control group) and thirty with the RADPAD (study group). Two separate methods were used to measure dose to a single operator. Thermoluminescent dosimeter (TLD) badges were used to measure hand, eye, and unshielded body dose. A direct dosimeter with digital readout was also used to measure eye and unshielded body dose. To allow for variation between control and study groups, dose per unit time was calculated. TLD results demonstrated a significant reduction in median body dose per unit time for the study group compared with controls (p = 0.001), corresponding to a mean dose reduction rate of 65 %. Median eye and hand dose per unit time were also reduced in the study group compared with control group, however, this was not statistically significant (p = 0.081 for eye, p = 0.628 for hand). Direct dosimeter readings also showed statistically significant reduction in median unshielded body dose rate for the study group compared with controls (p = 0.037). Eye dose rate was reduced for the study group but this was not statistically significant (p = 0.142). Initial results are encouraging. Use of the shield resulted in a statistically significant reduction in unshielded dose to the operator's body. Measured dose to the eye and hand of operator were also reduced but did not reach statistical significance in this pilot study.

Performance of Panasonic ZP-1460 Electronic Personal Dosemeter under Exposure Conditions Likely to be Found at Fukushima Daiichi Nuclear Power Plant

NASA Astrophysics Data System (ADS)

Tsujimura, Norio; Yoshida, Tadayoshi; Hoshi, Katsuya; Momose, Takumaro

A study on the performance of the Panasonic ZP-1460 electronic personal dosemeter, the model used in the aftermath of the Fukushima Daiichi nuclear power plant accident in March 2011, was conducted under actual exposure situations likely encountered in the plant. The tests pertained to (1) the dose rate response over dose rates >100 mSv/h and (2) the angular response on an anthropomorphic phantom exposed to the rotational and isotropic irradiation geometries. The test results confirmed that the dosemeter provides Hp(10) as a reasonably close estimate of the effective dose for any exposure geometries. The dosemeter response data evaluated in this study can be utilized for converting dosemeter readings to the absorbed dose to any organs and tissues for epidemiologic purposes.

SU-C-16A-02: A Beryllium Oxide (BeO) Fibre-Coupled Luminescence Dosimeter for High Dose Rate Brachytherapy

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

Santos, A; Institute for Photonics and Advanced Sensing and School of Chem and Phys, Adelaide, South Australia; Mohammadi, M

Purpose: Beryllium oxide (BeO) ceramics have an effective atomic number, zeff ∼7.1, closely matched to water, zeff ∼7.4. The purpose of this study was to evaluate the use of a beryllium oxide (BeO) ceramic fibrecoupled luminescence dosimeter, named RL/OSL BeO FOD, for high dose rate (HDR) brachytherapy dosimetry. In our dosimetry system the radioluminescence (RL) of BeO ceramics is utilized for dose-rate measurements, and the optically stimulated luminescence (OSL) can be read post exposure for accumulated dose measurements. Methods: The RL/OSL BeO FOD consists of a 1 mm diameter × 1 mm long cylinder of BeO ceramic coupled to amore » 15 m long silica-silica optical fibre. The optical fibre is connected to a custom developed portable RL and OSL reader, located outside of the treatment suite. The x-ray energy response was evaluated using superficial x-rays, an Ir-192 source and high energy linear accelerators. The RL/OSL BeO FOD was then characterised for an Ir-192 source, investigating the dose response and angular dependency. A depth dose curve for the Ir-192 source was also measured. Results: The RL/OSL BeO FOD shows an under-response at low energy x-rays as expected. Though at higher x-ray energies, the OSL response continued to increase, while the RL response remained relatively constant. The dose response for the RL is found to be linear up to doses of 15 Gy, while the OSL response becomes more supralinear to doses above 15 Gy. Little angular dependency is observed and the depth dose curve measured agreed within 4% of that calculated based on TG-43. Conclusion: This works shows that the RL/OSL BeO FOD can be useful in HDR dosimetry. With the RL/OSL BeO FODs current size, it is capable of being inserted into intraluminal catheters and interstitial needles to verify HDR treatments.« less

Recommendations to harmonize European early warning dosimetry network systems

NASA Astrophysics Data System (ADS)

Dombrowski, H.; Bleher, M.; De Cort, M.; Dabrowski, R.; Neumaier, S.; Stöhlker, U.

2017-12-01

After the Chernobyl nuclear power plant accident in 1986, followed by the Fukushima Nuclear power plant accident 25 years later, it became obvious that real-time information is required to quickly gain radiological information. As a consequence, the European countries established early warning network systems with the aim to provide an immediate warning in case of a major radiological emergency, to supply reliable information on area dose rates, contamination levels, radioactivity concentrations in air and finally to assess public exposure. This is relevant for governmental decisions on intervention measures in an emergency situation. Since different methods are used by national environmental monitoring systems to measure area dose rate values and activity concentrations, there are significant differences in the results provided by different countries. Because European and neighboring countries report area dose rate data to a central data base operated on behalf of the European Commission, the comparability of the data is crucial for its meaningful interpretation, especially in the case of a nuclear accident with transboundary implications. Only by harmonizing measuring methods and data evaluation, is the comparability of the dose rate data ensured. This publication concentrates on technical requirements and methods with the goal to effectively harmonize area dose rate monitoring data provided by automatic early warning network systems. The requirements and procedures laid down in this publication are based on studies within the MetroERM project, taking into account realistic technical approaches and tested procedures.

Determination of the gamma-ray skyshine dose contribution in a Loss Of Shielding accident

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

Dennis, M.L.; Weiner, R.F.; Osborn, D.M.

2007-07-01

The goal of this research is to determine the gamma-ray dose contribution from skyshine. In a transportation accident involving the loss of lead gamma shielding, first responders to the accident will be exposed to both direct gamma radiation streaming from the exposed spent nuclear fuel and atmospherically reflected gamma radiation. The reflected radiation is referred to as skyshine and should contribute minimally to the overall dose; however, when there is minimal shielding above the exposed source, skyshine at large distances from the source must be considered. The program SKYDOSE developed by Shultis and Faw evaluates the gamma-ray skyshine dose frommore » a point, isotropic, polyenergetic, gamma-photon source. Assuming an infinite black wall shielding all direct radiation, the model assumes a first responder is located at varying distances from the wall. Skyshine doses are calculated both through SKYDOSE's integral line-beam method and an approximate approach prescribed by the National Council of Radiation Protection and Measurements. Initial results from SKYDOSE indicate nearly equivalent dose rates from either direct or skyshine radiation at nine meters from the wall, which seemed unusual and not readily explained. NCRP methodology, however, yields skyshine dose rates which are drastically smaller than direct dose rates at the same distance. Further investigation using the program MicroSkyshine{sup R}, which allows a variety of source configurations, suggests skyshine contributes minimally to dose in a loss-of-shielding accident. (authors)« less

SU-E-T-433: Field-In-Field Irradiation for Breast Cancer with VERO-4DRT System: A Feasibility Study

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

Hayashi, N; Mizuno, T; Takada, Y

2015-06-15

Purpose: The Vero-4DRT system is a dedicated system for high precision radiation therapy. However, the field size is limited at 15 cm x 15 cm and shapes by using multi-leaf collimator (MLC) without X-Jaw and Y-Jaw. Therefore VERO-4DRT system is not available to simple wedged irradiation for breast cancer. In this study, we suppose FIF with ring and/or tilt/pan angles whole breast irradiation (FIFWBI). The purpose of this study is to verify the feasibility of FIFWBI with VERO-4DRT system. Methods: As fundamental evaluation, we performed commissioning test with phantom. The absorbed dose evaluation at several reference points and dose distributionmore » including split area were performed. We planned 10 demonstrative shapes in phantom for measuring these contents with i-plan workstation (BrainLAB). As clinical evaluation, the dose distribution and dose indexes were evaluated with actual patient data. Five patients with breast cancer were designed FIFWBI radiotherapy plan with split fields. Then, the dose distribution and dose indexes (including Dmax, Dmin, D95, D5 and Homogeneity index) were evaluated in these plans. Results: As the results of fundamental evaluation, all absorbed dose errors between calculated and measured doses were within 2%. The gamma passing rates with 2 mm/3% criteria in all cases were 96±2%. As the results of clinical evaluation, the values of Dmax, D95, D50, D5, and Homogeneity Index were 41.7±0.90 Gy, 49.4±0.34 Gy, 52.26±0.24 Gy, and 1.39±0.03, respectively. For Japanese breast cancer patients, this technique was feasible. However, the large split region was happened in FIFWBI in case of patient with large breast. Conclusion: We evaluated the FIFWBI technique with VERO-4DRT system. This technique is feasible for Japanese patients, but the patient with large breast should be disagreed with this technique.« less

Multicenter phase II study of apatinib, a novel VEGFR inhibitor in heavily pretreated patients with metastatic triple-negative breast cancer.

PubMed

Hu, Xichun; Zhang, Jian; Xu, Binghe; Jiang, Zefei; Ragaz, Joseph; Tong, Zhongsheng; Zhang, Qingyuan; Wang, Xiaojia; Feng, Jifeng; Pang, Danmei; Fan, Minhao; Li, Jin; Wang, Biyun; Wang, Zhonghua; Zhang, Qunling; Sun, Si; Liao, Chunmei

2014-10-15

Apatinib is an oral, highly potent tyrosine-kinase inhibitor targeting VEGFR2. Phase I study showed the recommended dose of 750 mg/day with substantial antitumor activity. This phase II study aims to evaluate the optimum dose level for the efficacy and safety of apatinib monotherapy in heavily pretreated patients with metastatic triple negative breast cancer (mTNBC) in China. Phase IIa was first performed among 25 patients previously treated with anthracycline and/or taxane. All patients received apatinib 750 mg/day p.o. in a 4-week cycle. Subsequently, a phase IIb study of 59 patients was activated, with the endpoint progression-free survival (PFS). The dosage of drug for the Phase IIb was determined according to safety, tolerability and efficacy from the phase IIa study. As a result of toxicity associated with the 750 mg dose in phase IIa, the recommended initial dose of apatinib in the phase IIb was 500 mg/day. In phase IIb, grade 3/4 hematologic toxicities were thrombocytopenia (13.6%), leukopenia (6.8%), neutropenia (3.4%) and anemia (1.7%). The most frequent grade 3/4 nonhematologic toxicities were hand-foot syndrome, proteinuria, hypertension, and increased ALT. In the 56 evaluable patients, overall response rate and clinical benefit rate (CBR) were 10.7 and 25.0%, respectively. Median PFS and overall survival were 3.3 (95% CI 1.7-5.0) and 10.6 (95% CI 5.6-15.7) months, respectively. Our results indicate that apatinib dose of 500 mg rather than 750 mg is the recommended starting dose for the heavily pretreated mTNBC patients with measurable rate of partial response and PFS. © 2014 UICC.

Feasibility study on the verification of actual beam delivery in a treatment room using EPID transit dosimetry.

PubMed

Baek, Tae Seong; Chung, Eun Ji; Son, Jaeman; Yoon, Myonggeun

2014-12-04

The aim of this study is to evaluate the ability of transit dosimetry using commercial treatment planning system (TPS) and an electronic portal imaging device (EPID) with simple calibration method to verify the beam delivery based on detection of large errors in treatment room. Twenty four fields of intensity modulated radiotherapy (IMRT) plans were selected from four lung cancer patients and used in the irradiation of an anthropomorphic phantom. The proposed method was evaluated by comparing the calculated dose map from TPS and EPID measurement on the same plane using a gamma index method with a 3% dose and 3 mm distance-to-dose agreement tolerance limit. In a simulation using a homogeneous plastic water phantom, performed to verify the effectiveness of the proposed method, the average passing rate of the transit dose based on gamma index was high enough, averaging 94.2% when there was no error during beam delivery. The passing rate of the transit dose for 24 IMRT fields was lower with the anthropomorphic phantom, averaging 86.8% ± 3.8%, a reduction partially due to the inaccuracy of TPS calculations for inhomogeneity. Compared with the TPS, the absolute value of the transit dose at the beam center differed by -0.38% ± 2.1%. The simulation study indicated that the passing rate of the gamma index was significantly reduced, to less than 40%, when a wrong field was erroneously irradiated to patient in the treatment room. This feasibility study suggested that transit dosimetry based on the calculation with commercial TPS and EPID measurement with simple calibration can provide information about large errors for treatment beam delivery.

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

Cardiovascular effects of constant rate infusions of lidocaine, lidocaine and dexmedetomidine, and dexmedetomidine in dogs anesthetized at equipotent doses of sevoflurane.

PubMed

Moran-Muñoz, Rafael; Valverde, Alexander; Ibancovichi, J A; Acevedo-Arcique, Carlos M; Recillas-Morales, Sergio; Sanchez-Aparicio, Pedro; Osorio-Avalos, Jorge; Chavez-Monteagudo, Julio Raul

2017-07-01

This study evaluated the cardiovascular effects of a constant rate infusion (CRI) of lidocaine, lidocaine and dexmedetomidine, and dexmedetomidine in dogs anesthetized with sevoflurane at equipotent doses. Treatments consisted of T1-Lidocaine [loading dose 2 mg/kg body weight (BW), IV, and CRI of 100 μg/kg BW per min] at 1.4% end-tidal of sevoflurane (FE SEV ); T2-Dexmedetomidine (loading dose 2 μg/kg BW, IV, and CRI of 2 μg/kg BW per hour) and FE SEV 1.1%; and T3-Lidocaine-Dexmedetomidine using the same doses of T1 and T2 and FE SEV 0.8%. Constant rate infusion of lidocaine did not induce any cardiovascular changes; lidocaine and dexmedetomidine resulted in cardiovascular effects similar to dexmedetomidine alone. These effects were characterized by a significant ( P < 0.001) decrease in heart rate, cardiac output, cardiac index, oxygen delivery, and pulmonary vascular resistance index, and a significant ( P < 0.001) increase in mean and diastolic arterial pressure, systemic vascular resistance index, pulmonary arterial occlusion pressure and oxygen extraction ratio, compared with baseline values. In conclusion, a CRI of lidocaine combined with dexmedetomidine produces significant cardiovascular changes similar to those observed with dexmedetomidine alone.

Helical prospective ECG-gating in cardiac computed tomography: radiation dose and image quality.

PubMed

DeFrance, Tony; Dubois, Eric; Gebow, Dan; Ramirez, Alex; Wolf, Florian; Feuchtner, Gudrun M

2010-01-01

Helical prospective ECG-gating (pECG) may reduce radiation dose while maintaining the advantages of helical image acquisition for coronary computed tomography angiography (CCTA). Aim of this study was to evaluate helical pECG-gating in CCTA in regards to radiation dose and image quality. 86 patients undergoing 64-multislice CCTA were enrolled. pECG-gating was performed in patients with regular heart rates (HR) < 65 bpm; with the gating window set at 70-85% of the cardiac cycle. All patients received oral and some received additional IV beta-blockers to achieve HR < 65 bpm. In patients with higher or irregular HR, or for functional evaluation, retrospective ECG-gating (rECG) was performed. The average X-ray dose was estimated from the dose length product. Each arterial segment (modified AHA/ACC 17-segment-model) was evaluated on a 4-point image quality scale (4 = excellent; 3 = good, mild artefact; 2 = acceptable, some artefact, 1 = uninterpretable). pECG-gating was applied in 57 patients, rECG-gating in 29 patients. There was no difference in age, gender, body mass index, scan length or tube output settings between both groups. HR in the pECG-group was 54.7 bpm (range, 43-64). The effective radiation dose was significantly lower for patients scanned with pECG-gating with mean 6.9 mSv +/- 1.9 (range, 2.9-10.7) compared to rECG with 16.9 mSv +/- 4.1 (P < 0.001), resulting in a mean dose reduction of 59.2%. For pECG-gating, out of 969 coronary segments, 99.3% were interpretable. Image quality was excellent in 90.2%, good in 7.8%, acceptable in 1.3% and non-interpretable in 0.7% (n = 7 segments). For patients with steady heart rates <65 bpm, helical prospective ECG-gating can significantly lower the radiation dose while maintaining high image quality.

Using temperature-switching approach to evaluate the ELDRS of bipolar devices

NASA Astrophysics Data System (ADS)

Li, Xiaolong; Lu, Wu; Wang, Xin; Guo, Qi; Yu, Xin; He, Chengfa; Sun, Jing; Liu, Mohan; Yao, Shuai; Wei, Xinyu

2017-12-01

Enhanced low-dose rate sensitivity (ELDRS) exhibited at low-dose rates (LDRs) by most bipolar devices is considered as one of the main concerns for spacecraft reliability. In this work, a time-saving and conservative approach - temperature-switching approach (TSA) - to simulate the ELDRS of bipolar devices is presented. Good agreement is observed between the predictive curve obtained with the TSA and the LDR data, and TSA provides us with a new insight into the test technique for ELDRS. Additionally, the mechanisms of TSA are analyzed in this paper.

First-principles X-ray absorption dose calculation for time-dependent mass and optical density.

PubMed

Berejnov, Viatcheslav; Rubinstein, Boris; Melo, Lis G A; Hitchcock, Adam P

2018-05-01

A dose integral of time-dependent X-ray absorption under conditions of variable photon energy and changing sample mass is derived from first principles starting with the Beer-Lambert (BL) absorption model. For a given photon energy the BL dose integral D(e, t) reduces to the product of an effective time integral T(t) and a dose rate R(e). Two approximations of the time-dependent optical density, i.e. exponential A(t) = c + aexp(-bt) for first-order kinetics and hyperbolic A(t) = c + a/(b + t) for second-order kinetics, were considered for BL dose evaluation. For both models three methods of evaluating the effective time integral are considered: analytical integration, approximation by a function, and calculation of the asymptotic behaviour at large times. Data for poly(methyl methacrylate) and perfluorosulfonic acid polymers measured by scanning transmission soft X-ray microscopy were used to test the BL dose calculation. It was found that a previous method to calculate time-dependent dose underestimates the dose in mass loss situations, depending on the applied exposure time. All these methods here show that the BL dose is proportional to the exposure time D(e, t) ≃ K(e)t.

An assessment of a 3D EPID-based dosimetry system using conventional two- and three-dimensional detectors for VMAT.

PubMed

Stevens, S; Dvorak, P; Spevacek, V; Pilarova, K; Bray-Parry, M; Gesner, J; Richmond, A

2018-01-01

To provide a 3D dosimetric evaluation of a commercial portal dosimetry system using 2D/3D detectors under ideal conditions using VMAT. A 2D ion chamber array, radiochromic film and gel dosimeter were utilised to provide a dosimetric evaluation of transit phantom and pre-treatment 'fluence' EPID back-projected dose distributions for a standard VMAT plan. In-house 2D and 3D gamma methods compared pass statistics relative to each dosimeter and TPS dose distributions. Fluence mode and transit EPID dose distributions back-projected onto phantom geometry produced 2D gamma pass rates in excess of 97% relative to other tested detectors and exported TPS dose planes when a 3%, 3 mm global gamma criterion was applied. Use of a gel dosimeter within a glass vial allowed comparison of measured 3D dose distributions versus EPID 3D dose and TPS calculated distributions. 3D gamma comparisons between modalities at 3%, 3 mm gave pass rates in excess of 92%. Use of fluence mode was indicative of transit results under ideal conditions with slightly reduced dose definition. 3D EPID back projected dose distributions were validated against detectors in both 2D and 3D. Cross validation of transit dose delivered to a patient is limited due to reasons of practicality and the tests presented are recommended as a guideline for 3D EPID dosimetry commissioning; allowing direct comparison between detector, TPS, fluence and transit modes. The results indicate achievable gamma scores for a complex VMAT plan in a homogenous phantom geometry and contributes to growing experience of 3D EPID dosimetry. Copyright © 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

Islet Oxygen Consumption Rate (OCR) Dose Predicts Insulin Independence in Clinical Islet Autotransplantation.

PubMed

Papas, Klearchos K; Bellin, Melena D; Sutherland, David E R; Suszynski, Thomas M; Kitzmann, Jennifer P; Avgoustiniatos, Efstathios S; Gruessner, Angelika C; Mueller, Kathryn R; Beilman, Gregory J; Balamurugan, Appakalai N; Loganathan, Gopalakrishnan; Colton, Clark K; Koulmanda, Maria; Weir, Gordon C; Wilhelm, Josh J; Qian, Dajun; Niland, Joyce C; Hering, Bernhard J

2015-01-01

Reliable in vitro islet quality assessment assays that can be performed routinely, prospectively, and are able to predict clinical transplant outcomes are needed. In this paper we present data on the utility of an assay based on cellular oxygen consumption rate (OCR) in predicting clinical islet autotransplant (IAT) insulin independence (II). IAT is an attractive model for evaluating characterization assays regarding their utility in predicting II due to an absence of confounding factors such as immune rejection and immunosuppressant toxicity. Membrane integrity staining (FDA/PI), OCR normalized to DNA (OCR/DNA), islet equivalent (IE) and OCR (viable IE) normalized to recipient body weight (IE dose and OCR dose), and OCR/DNA normalized to islet size index (ISI) were used to characterize autoislet preparations (n = 35). Correlation between pre-IAT islet product characteristics and II was determined using receiver operating characteristic analysis. Preparations that resulted in II had significantly higher OCR dose and IE dose (p<0.001). These islet characterization methods were highly correlated with II at 6-12 months post-IAT (area-under-the-curve (AUC) = 0.94 for IE dose and 0.96 for OCR dose). FDA/PI (AUC = 0.49) and OCR/DNA (AUC = 0.58) did not correlate with II. OCR/DNA/ISI may have some utility in predicting outcome (AUC = 0.72). Commonly used assays to determine whether a clinical islet preparation is of high quality prior to transplantation are greatly lacking in sensitivity and specificity. While IE dose is highly predictive, it does not take into account islet cell quality. OCR dose, which takes into consideration both islet cell quality and quantity, may enable a more accurate and prospective evaluation of clinical islet preparations.

Evaluation of the radiobiological gamma index with motion interplay in tangential IMRT breast treatment

PubMed Central

Sumida, Iori; Yamaguchi, Hajime; Das, Indra J.; Kizaki, Hisao; Aboshi, Keiko; Tsujii, Mari; Yamada, Yuji; Tamari, Kiesuke; Suzuki, Osamu; Seo, Yuji; Isohashi, Fumiaki; Yoshioka, Yasuo; Ogawa, Kazuhiko

2016-01-01

The purpose of this study was to evaluate the impact of the motion interplay effect in early-stage left-sided breast cancer intensity-modulated radiation therapy (IMRT), incorporating the radiobiological gamma index (RGI). The IMRT dosimetry for various breathing amplitudes and cycles was investigated in 10 patients. The predicted dose was calculated using the convolution of segmented measured doses. The physical gamma index (PGI) of the planning target volume (PTV) and the organs at risk (OAR) was calculated by comparing the original with the predicted dose distributions. The RGI was calculated from the PGI using the tumor control probability (TCP) and the normal tissue complication probability (NTCP). The predicted mean dose and the generalized equivalent uniform dose (gEUD) to the target with various breathing amplitudes were lower than the original dose (P < 0.01). The predicted mean dose and gEUD to the OARs with motion were higher than for the original dose to the OARs (P < 0.01). However, the predicted data did not differ significantly between the various breathing cycles for either the PTV or the OARs. The mean RGI gamma passing rate for the PTV was higher than that for the PGI (P < 0.01), and for OARs, the RGI values were higher than those for the PGI (P < 0.01). The gamma passing rates of the RGI for the target and the OARs other than the contralateral lung differed significantly from those of the PGI under organ motion. Provided an NTCP value <0.05 is considered acceptable, it may be possible, by taking breathing motion into consideration, to escalate the dose to achieve the PTV coverage without compromising the TCP. PMID:27534793

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

Russell Feder and Mahmoud Z. Yousef

Neutronics analysis to find nuclear heating rates and personnel dose rates were conducted in support of the integration of diagnostics in to the ITER Upper Port Plugs. Simplified shielding models of the Visible-Infrared diagnostic and of the ECH heating system were incorporated in to the ITER global CAD model. Results for these systems are representative of typical designs with maximum shielding and a small aperture (Vis-IR) and minimal shielding with a large aperture (ECH). The neutronics discrete-ordinates code ATTILA® and SEVERIAN® (the ATTILA parallel processing version) was used. Material properties and the 500 MW D-T volume source were taken frommore » the ITER “Brand Model” MCNP benchmark model. A biased quadrature set equivelant to Sn=32 and a scattering degree of Pn=3 were used along with a 46-neutron and 21-gamma FENDL energy subgrouping. Total nuclear heating (neutron plug gamma heating) in the upper port plugs ranged between 380 and 350 kW for the Vis-IR and ECH cases. The ECH or Large Aperture model exhibited lower total heating but much higher peak volumetric heating on the upper port plug structure. Personnel dose rates are calculated in a three step process involving a neutron-only transport calculation, the generation of activation volume sources at pre-defined time steps and finally gamma transport analyses are run for selected time steps. ANSI-ANS 6.1.1 1977 Flux-to-Dose conversion factors were used. Dose rates were evaluated for 1 full year of 500 MW DT operation which is comprised of 3000 1800-second pulses. After one year the machine is shut down for maintenance and personnel are permitted to access the diagnostic interspace after 2-weeks if dose rates are below 100 μSv/hr. Dose rates in the Visible-IR diagnostic model after one day of shutdown were 130 μSv/hr but fell below the limit to 90 μSv/hr 2-weeks later. The Large Aperture or ECH style shielding model exhibited higher and more persistent dose rates. After 1-day the dose rate was 230 μSv/hr but was still at 120 μSv/hr 4-weeks later. __________________________________________________« less

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

Russell E. Feder and Mahmoud Z. Youssef

Neutronics analysis to find nuclear heating rates and personnel dose rates were conducted in support of the integration of diagnostics in to the ITER Upper Port Plugs. Simplified shielding models of the Visible-Infrared diagnostic and of a large aperture diagnostic were incorporated in to the ITER global CAD model. Results for these systems are representative of typical designs with maximum shielding and a small aperture (Vis-IR) and minimal shielding with a large aperture. The neutronics discrete-ordinates code ATTILA® and SEVERIAN® (the ATTILA parallel processing version) was used. Material properties and the 500 MW D-T volume source were taken from themore » ITER “Brand Model” MCNP benchmark model. A biased quadrature set equivelant to Sn=32 and a scattering degree of Pn=3 were used along with a 46-neutron and 21-gamma FENDL energy subgrouping. Total nuclear heating (neutron plug gamma heating) in the upper port plugs ranged between 380 and 350 kW for the Vis-IR and Large Aperture cases. The Large Aperture model exhibited lower total heating but much higher peak volumetric heating on the upper port plug structure. Personnel dose rates are calculated in a three step process involving a neutron-only transport calculation, the generation of activation volume sources at pre-defined time steps and finally gamma transport analyses are run for selected time steps. ANSI-ANS 6.1.1 1977 Flux-to-Dose conversion factors were used. Dose rates were evaluated for 1 full year of 500 MW DT operation which is comprised of 3000 1800-second pulses. After one year the machine is shut down for maintenance and personnel are permitted to access the diagnostic interspace after 2-weeks if dose rates are below 100 μSv/hr. Dose rates in the Visible-IR diagnostic model after one day of shutdown were 130 μSv/hr but fell below the limit to 90 μSv/hr 2-weeks later. The Large Aperture style shielding model exhibited higher and more persistent dose rates. After 1-day the dose rate was 230 μSv/hr but was still at 120 μSv/hr 4-weeks later.« less

Dose specification and quality assurance of RTOG protocol 95-17; a cooperative group study of 192Ir breast implants as sole therapy

PubMed Central

Ibbott, Geoffrey S.; Hanson, W.F.; Martin, Elizabeth; Kuske, Robert R.; Arthur, Douglas; Rabinovitch, Rachel; White, Julia; Wilenzick, Raymond M.; Harris, Irene; Tailor, Ramesh C.

2007-01-01

Purpose RTOG protocol 95-17 was a phase I/II trial to evaluate multi-catheter brachytherapy as the sole method of adjuvant breast radiotherapy for stage I/II breast carcinoma following breast conserving surgery. Low or high dose rate sources were allowed. Dose prescription and treatment evaluation were based on recommendations in ICRU Report 58, and included the parameters mean central dose (MCD), average peripheral dose, dose homogeneity index (DHI), and the dimensions of the low and high dose regions. Methods and Materials Three levels of quality assurance were implemented: (1) Credentialing of institutions was required prior to entering patients onto the study. (2) Rapid review of each treatment plan was conducted prior to treatment, and (3) Retrospective review was performed by the Radiological Physics Center in conjunction with the study chairman and RTOG dosimetry staff. Results Credentialing focused on the accuracy of dose calculation algorithm and compliance with protocol guidelines. Rapid review was designed to identify and correct deviations from the protocol prior to treatment. The retrospective review involved recalculation of dosimetry parameters and review of dose distributions to evaluate the treatment. Specifying both central and peripheral doses resulted in uniform dose distributions, with a mean dose homogeneity index of 0.83 ±0.06. Conclusions Vigorous quality assurance resulted in a high-quality study with few deviations; only 4 of 100 patients were judged as minor variations from protocol and no patient was judged a major deviation. This study should be considered a model for quality assurance of future trials. PMID:18035213

Effectiveness of a Third Dose of MMR Vaccine for Mumps Outbreak Control.

PubMed

Cardemil, Cristina V; Dahl, Rebecca M; James, Lisa; Wannemuehler, Kathleen; Gary, Howard E; Shah, Minesh; Marin, Mona; Riley, Jacob; Feikin, Daniel R; Patel, Manisha; Quinlisk, Patricia

2017-09-07

The effect of a third dose of the measles-mumps-rubella (MMR) vaccine in stemming a mumps outbreak is unknown. During an outbreak among vaccinated students at the University of Iowa, health officials implemented a widespread MMR vaccine campaign. We evaluated the effectiveness of a third dose for outbreak control and assessed for waning immunity. Of 20,496 university students who were enrolled during the 2015-2016 academic year, mumps was diagnosed in 259 students. We used Fisher's exact test to compare unadjusted attack rates according to dose status and years since receipt of the second MMR vaccine dose. We used multivariable time-dependent Cox regression models to evaluate vaccine effectiveness, according to dose status (three vs. two doses and two vs. no doses) after adjustment for the number of years since the second dose. Before the outbreak, 98.1% of the students had received at least two doses of MMR vaccine. During the outbreak, 4783 received a third dose. The attack rate was lower among the students who had received three doses than among those who had received two doses (6.7 vs. 14.5 cases per 1000 population, P<0.001). Students had more than nine times the risk of mumps if they had received the second MMR dose 13 years or more before the outbreak. At 28 days after vaccination, receipt of the third vaccine dose was associated with a 78.1% lower risk of mumps than receipt of a second dose (adjusted hazard ratio, 0.22; 95% confidence interval, 0.12 to 0.39). The vaccine effectiveness of two doses versus no doses was lower among students with more distant receipt of the second vaccine dose. Students who had received a third dose of MMR vaccine had a lower risk of mumps than did those who had received two doses, after adjustment for the number of years since the second dose. Students who had received a second dose of MMR vaccine 13 years or more before the outbreak had an increased risk of mumps. These findings suggest that the campaign to administer a third dose of MMR vaccine improved mumps outbreak control and that waning immunity probably contributed to propagation of the outbreak. (Funded by the Centers for Disease Control and Prevention.).

Dose assessment of digital tomosynthesis in pediatric imaging

NASA Astrophysics Data System (ADS)

Gislason, Amber; Elbakri, Idris A.; Reed, Martin

2009-02-01

We investigated the potential for digital tomosynthesis (DT) to reduce pediatric x-ray dose while maintaining image quality. We utilized the DT feature (VolumeRadTM) on the GE DefiniumTM 8000 flat panel system installed in the Winnipeg Children's Hospital. Facial bones, cervical spine, thoracic spine, and knee of children aged 5, 10, and 15 years were represented by acrylic phantoms for DT dose measurements. Effective dose was estimated for DT and for corresponding digital radiography (DR) and computed tomography (CT) patient image sets. Anthropomorphic phantoms of selected body parts were imaged by DR, DT, and CT. Pediatric radiologists rated visualization of selected anatomic features in these images. Dose and image quality comparisons between DR, DT, and CT determined the usefulness of tomosynthesis for pediatric imaging. CT effective dose was highest; total DR effective dose was not always lowest - depending how many projections were in the DR image set. For the cervical spine, DT dose was close to and occasionally lower than DR dose. Expert radiologists rated visibility of the central facial complex in a skull phantom as better than DR and comparable to CT. Digital tomosynthesis has a significantly lower dose than CT. This study has demonstrated DT shows promise to replace CT for some facial bones and spinal diagnoses. Other clinical applications will be evaluated in the future.

Development of a novel low-radiation-absorbent lok-bar to reduce X-ray scattering and absorption in RapidArc® treatment planning and dose delivery.

PubMed

Monzen, Hajime; Kubo, Kazuki; Tamura, Mikoto; Hayakawa, Masaru; Nishimura, Yasumasa

2017-05-01

We developed a novel low-radiation-absorbent lok-bar (HM-bar) that is used to secure the immobilizers to the couch. The aim of this study was to investigate the X-ray scattering and absorption properties of the HM-bar in computed tomography (CT) simulation and radiotherapy dose delivery using the Varian Exact™ lok-bar (VL-bar) as a benchmark. CT images were obtained with or without lok-bar, and then each image was visually evaluated for artifacts. The attenuation rates for each lok-bar were measured using a farmer-type ionization chamber (PTW30013) and the I'mRT phantom (IBA Dosimetry GmbH). Measurement points were between gantry angles of 110 and 180°. The treatment apparatus was a NovalisTx (Brainlab AG); X-ray energies were set at 6 MV and 10 MV. In the presence of each lok-bar, the radiation dose was measured in accordance with 10 volumetric modulated arc therapy-stereotactic body radiation therapy (VMAT-SBRT) plans for lung cancer. Artifacts were seldom observed in the CT scans of the HM-bar. The attenuation rate of each lok-bar was higher when the X-ray energy was set at 6 MV than at 10 MV. The highest attenuation rate in the VL-bar was observed at a gantry angle of 112°; the rates were 22.4% at 6 MV and 19.3% at 10 MV. Similarly, the highest attenuation rate for the HM-bar was also observed at a gantry angle of 112°; the rates were 12.2% and 10.1% at 6 MV and 10 MV, respectively. When the VL-bar was evaluated, the isocenter dose of the VMAT-SBRT plans was attenuated by 2.6% as a maximum case. In the case of the HM-bar, the maximum attenuation was 1.4%. In the measurements of each VMAT-SBRT plan, the difference of the dose attenuation rate between the VL-bar and HM-bar was approximately 1%. The HM-bar could be used to minimize the occurrence of artifacts and provide good images in CT scans regarding radiotherapy planning and dose calculation. It can be used for patient therapy at hospitals to provide accurate dose delivery because of its low X-ray scattering and absorption characteristics. © 2017 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of Physicists in Medicine.

Neutron dose estimation in a zero power nuclear reactor

NASA Astrophysics Data System (ADS)

Triviño, S.; Vedelago, J.; Cantargi, F.; Keil, W.; Figueroa, R.; Mattea, F.; Chautemps, A.; Santibañez, M.; Valente, M.

2016-10-01

This work presents the characterization and contribution of neutron and gamma components to the absorbed dose in a zero power nuclear reactor. A dosimetric method based on Fricke gel was implemented to evaluate the separation between dose components in the mixed field. The validation of this proposed method was performed by means of direct measurements of neutron flux in different positions using Au and Mg-Ni activation foils. Monte Carlo simulations were conversely performed using the MCNP main code with a dedicated subroutine to incorporate the exact complete geometry of the nuclear reactor facility. Once nuclear fuel elements were defined, the simulations computed the different contributions to the absorbed dose in specific positions inside the core. Thermal/epithermal contributions of absorbed dose were assessed by means of Fricke gel dosimetry using different isotopic compositions aimed at modifying the sensitivity of the dosimeter for specific dose components. Clear distinctions between gamma and neutron capture dose were obtained. Both Monte Carlo simulations and experimental results provided reliable estimations about neutron flux rate as well as dose rate during the reactor operation. Simulations and experimental results are in good agreement in every positions measured and simulated in the core.

Evaluation of Low- Versus High-dose Valganciclovir for Prevention of Cytomegalovirus Disease in High-risk Renal Transplant Recipients.

PubMed

Gabardi, Steven; Asipenko, Natalya; Fleming, James; Lor, Kevin; McDevitt-Potter, Lisa; Mohammed, Anisa; Rogers, Christin; Tichy, Eric M; Weng, Renee; Lee, Ruth-Ann

2015-07-01

Despite proven efficacy of prolonged cytomegalovirus (CMV) prophylaxis using valganciclovir 900 mg/day, some centers use 450 mg/day due to reported success and cost savings. This multicenter, retrospective study compared the efficacy and safety of 6 months of low-dose versus high-dose valganciclovir prophylaxis in high-risk, donor-positive/recipient-negative, renal transplant recipients (RTR). Two hundred thirty-seven high-risk RTR (low-dose group = valganciclovir 450 mg/day [n = 130]; high-dose group = valganciclovir 900 mg/day [n = s7]) were evaluated for 1-year CMV disease prevalence. Breakthrough CMV, resistant CMV, biopsy-proven acute rejection (BPAR), graft loss, opportunistic infections (OI), new-onset diabetes after transplantation (NODAT), premature valganciclovir discontinuation, renal function and myelosuppression were also assessed. Patient demographics and transplant characteristics were comparable. Induction and maintenance immunosuppression were similar, except for more early steroid withdrawal in the high-dose group. Similar proportions of patients developed CMV disease (14.6% vs 24.3%; P = 0.068); however, controlling CMV risk factor differences through multivariate logistic regression revealed significantly lower CMV disease in the low-dose group (P = 0.02; odds ratio, 0.432, 95% confidence interval, 0.211-0.887). Breakthrough and resistant CMV occurred at similar frequencies. There was no difference in renal function or rates of biopsy-proven acute rejection, graft loss, opportunistic infections, or new-onset diabetes after transplantation. The high-dose group had significantly lower mean white blood cell counts at months 5 and 6; however, premature valganciclovir discontinuation rates were similar. Low-dose and high-dose valganciclovir regimens provide similar efficacy in preventing CMV disease in high-risk RTR, with a reduced incidence of leukopenia associated with the low-dose regimen and no difference in resistant CMV. Low-dose valganciclovir may provide a significant cost avoidance benefit.

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

Evaluation of oral and subcutaneous delivery of an experimental canarypox recombinant canine distemper vaccine in the Siberian polecate (Mustela eversmanni)

USGS Publications Warehouse

Wimsatt, Jeffrey; Biggins, Dean E.; Innes, Kim; Taylor, Bobbi; Garell, Della

2003-01-01

We assessed the safety and efficacy of an experimental canarypox-vectored recombinant canine distemper virus (CDV) subunit vaccine in the Siberian polecat (Mustela eversmanni), a close relative of the black-footed ferret, (M. nigripes), an endangered species that is highly susceptible to the virus. Siberian polecats were randomized into six treatment groups. Recombinant canine distemper vaccine was administered s.c. at three dose levels (104.5, 105.0, and 105.5 plaque-forming units [PFU] per dose) and was administered orally by spraying the vaccine into the oropharnyx at two dose levels (105.5, 108.0 PFU per dose). The sixth group of control animals was not vaccinated. For both routes of administration, two 1-ml doses of reconstituted vaccine were delivered 4 wk apart, followed by live virus challenge 3 wk after the second vaccination. During the challenge, Synder Hill test strain CDV obtained from the National Veterinary Services Laboratory in Ames, Iowa, was administered i.p. Serial blood samples for CDV serology were collected immediately before vaccination and challenge, and 10, 15, and 20 days after challenge. Clinical signs and body weights were recorded up to 32 days after challenge. The survival rate in animals receiving vaccine at the highest oral dose (108.0 PFU per dose) was 83.3%. Survival rate was 50.0% in the high s.c. and 60.0% in the medium s.c. groups. All animals in the low–s.c. dose, low–oral dose, and control groups died after exposure. Vaccine dose overall (oral and s.c.) and dose in response to s.c. administration when considered alone were significant predictors of survival (P = 0.006 and P = 0.04, respectively). Among the polecats challenged with virulent virus, those that died became sick sooner than those that survived. Animals that died lost significantly more weight during the 10 days after challenge than did animals that survived (P = 0.02). Survival rates did not differ by sex, founder female status, or breeding pedigree in any of the treatment groups. Survival rates were higher in animals with increasing serum neutralization titers (P = 0.027). This study demonstrates the efficacy of oral delivery of a recombinant CDV vaccine in the Siberian polecat. Further studies are needed to evaluate the safety and efficacy of vectored recombinant vaccines in highly susceptible species and especially in those species in which vaccination with modified live CDV has led to disease.

Evaluation of oral and subcutaneous delivery of an experimental canarypox recombinant canine distemper vaccine in the Siberian polecat (Mustela eversmanni).

PubMed

Wimsatt, Jeffrey; Biggins, Dean; Innes, Kim; Taylor, Bobbi; Garell, Della

2003-03-01

We assessed the safety and efficacy of an experimental canarypox-vectored recombinant canine distemper virus (CDV) subunit vaccine in the Siberian polecat (Mustela eversmanni), a close relative of the black-footed ferret, (M. nigripes), an endangered species that is highly susceptible to the virus. Siberian polecats were randomized into six treatment groups. Recombinant canine distemper vaccine was administered s.c. at three dose levels (10(4.5), 10(5.0), and 10(5.5) plaque-forming units [PFU] per dose) and was administered orally by spraying the vaccine into the oropharnyx at two dose levels (10(5.5), 10(8.0) PFU per dose). The sixth group of control animals was not vaccinated. For both routes of administration, two 1-ml doses of reconstituted vaccine were delivered 4 wk apart, followed by live virus challenge 3 wk after the second vaccination. During the challenge, Synder Hill test strain CDV obtained from the National Veterinary Services Laboratory in Ames, Iowa, was administered i.p. Serial blood samples for CDV serology were collected immediately before vaccination and challenge, and 10, 15, and 20 days after challenge. Clinical signs and body weights were recorded up to 32 days after challenge. The survival rate in animals receiving vaccine at the highest oral dose (10(8.0) PFU per dose) was 83.3%. Survival rate was 50.0% in the high s.c. and 60.0% in the medium s.c. groups. All animals in the low-s.c. dose, low-oral dose, and control groups died after exposure. Vaccine dose overall (oral and s.c.) and dose in response to s.c. administration when considered alone were significant predictors of survival (P = 0.006 and P = 0.04, respectively). Among the polecats challenged with virulent virus, those that died became sick sooner than those that survived. Animals that died lost significantly more weight during the 10 days after challenge than did animals that survived (P = 0.02). Survival rates did not differ by sex, founder female status, or breeding pedigree in any of the treatment groups. Survival rates were higher in animals with increasing serum neutralization titers (P = 0.027). This study demonstrates the efficacy of oral delivery of a recombinant CDV vaccine in the Siberian polecat. Further studies are needed to evaluate the safety and efficacy of vectored recombinant vaccines in highly susceptible species and especially in those species in which vaccination with modified live CDV has led to disease.

Effects of infectious virus dose and bloodmeal delivery method on susceptibility of Aedes aegypti and Aedes albopictus to chikungunya virus.

PubMed

Pesko, Kendra; Westbrook, Catherine J; Mores, Christopher N; Lounibos, L Philip; Reiskind, Michael H

2009-03-01

Chikungunya virus (CHIKV) is an arbovirus (genus Alphavirus, family Togaviridae) that has recently caused disease outbreaks in the Indian Ocean basin and southern Europe. These outbreaks could be associated with a possible shift in primary vector from Aedes aegypti to Ae. albopictus. To evaluate vector competence differences in possible CHIKV vectors, we evaluated the dose-dependant susceptibility of Florida strains of Ae. albopictus and Ae. aegypti for infection with a La Réunion island strain of CHIKV. Pledget and water-jacketed membrane feeding systems were also evaluated. We show that both Aedes spp. were susceptible to the highest CHIKV doses, whereas only Ae. albopictus developed disseminated infections after exposure to the two lowest doses. Infection rates for both mosquito species were significantly affected by the bloodmeal delivery method used. This information is important in assessing risk of an outbreak of imported CHIKV in the United States, in determining differences in vectorial capacity of these two vector species, and in evaluating arbovirus delivery methods in the laboratory.

Effects of Infectious Virus Dose and Bloodmeal Delivery Method on Susceptibility of Aedes aegypti and Aedes albopictus to Chikungunya Virus

PubMed Central

Pesko, Kendra; Westbrook, Catherine J.; Mores, Christopher N.; Lounibos, L. Philip; Reiskind, Michael H.

2009-01-01

Chikungunya virus (CHIKV) is an arbovirus (genus Alphavirus, family Togaviridae) that has recently caused disease outbreaks in the Indian Ocean basin and southern Europe. These outbreaks could be associated with a possible shift in primary vector from Aedes aegypti to Ae. albopictus. To evaluate vector competence differences in possible CHIKV vectors, we evaluated the dose-dependant susceptibility of Florida strains of Ae. albopictus and Ae. aegypti for infection with a La Réunion island strain of CHIKV. Pledget and water-jacketed membrane feeding systems were also evaluated. We show that both Aedes spp. were susceptible to the highest CHIKV doses, whereas only Ae. albopictus developed disseminated infections after exposure to the two lowest doses. Infection rates for both mosquito species were significantly affected by the bloodmeal delivery method used. This information is important in assessing risk of an outbreak of imported CHIKV in the United States, in determining differences in vectorial capacity of these two vector species, and in evaluating arbovirus delivery methods in the laboratory. PMID:19351094

Error detection capability of a novel transmission detector: a validation study for online VMAT monitoring.

PubMed

Pasler, Marlies; Michel, Kilian; Marrazzo, Livia; Obenland, Michael; Pallotta, Stefania; Björnsgard, Mari; Lutterbach, Johannes

2017-09-01

The purpose of this study was to characterize a new single large-area ionization chamber, the integral quality monitor system (iRT, Germany), for online and real-time beam monitoring. Signal stability, monitor unit (MU) linearity and dose rate dependence were investigated for static and arc deliveries and compared to independent ionization chamber measurements. The dose verification capability of the transmission detector system was evaluated by comparing calculated and measured detector signals for 15 volumetric modulated arc therapy plans. The error detection sensitivity was tested by introducing MLC position and linac output errors. Deviations in dose distributions between the original and error-induced plans were compared in terms of detector signal deviation, dose-volume histogram (DVH) metrics and 2D γ-evaluation (2%/2 mm and 3%/3 mm). The detector signal is linearly dependent on linac output and shows negligible (<0.4%) dose rate dependence up to 460 MU min -1 . Signal stability is within 1% for cumulative detector output; substantial variations were observed for the segment-by-segment signal. Calculated versus measured cumulative signal deviations ranged from  -0.16%-2.25%. DVH, mean 2D γ-value and detector signal evaluations showed increasing deviations with regard to the respective reference with growing MLC and dose output errors; good correlation between DVH metrics and detector signal deviation was found (e.g. PTV D mean : R 2   =  0.97). Positional MLC errors of 1 mm and errors in linac output of 2% were identified with the transmission detector system. The extensive tests performed in this investigation show that the new transmission detector provides a stable and sensitive cumulative signal output and is suitable for beam monitoring during patient treatment.

Error detection capability of a novel transmission detector: a validation study for online VMAT monitoring

NASA Astrophysics Data System (ADS)

Pasler, Marlies; Michel, Kilian; Marrazzo, Livia; Obenland, Michael; Pallotta, Stefania; Björnsgard, Mari; Lutterbach, Johannes

2017-09-01

The purpose of this study was to characterize a new single large-area ionization chamber, the integral quality monitor system (iRT, Germany), for online and real-time beam monitoring. Signal stability, monitor unit (MU) linearity and dose rate dependence were investigated for static and arc deliveries and compared to independent ionization chamber measurements. The dose verification capability of the transmission detector system was evaluated by comparing calculated and measured detector signals for 15 volumetric modulated arc therapy plans. The error detection sensitivity was tested by introducing MLC position and linac output errors. Deviations in dose distributions between the original and error-induced plans were compared in terms of detector signal deviation, dose-volume histogram (DVH) metrics and 2D γ-evaluation (2%/2 mm and 3%/3 mm). The detector signal is linearly dependent on linac output and shows negligible (<0.4%) dose rate dependence up to 460 MU min-1. Signal stability is within 1% for cumulative detector output; substantial variations were observed for the segment-by-segment signal. Calculated versus measured cumulative signal deviations ranged from  -0.16%-2.25%. DVH, mean 2D γ-value and detector signal evaluations showed increasing deviations with regard to the respective reference with growing MLC and dose output errors; good correlation between DVH metrics and detector signal deviation was found (e.g. PTV D mean: R 2  =  0.97). Positional MLC errors of 1 mm and errors in linac output of 2% were identified with the transmission detector system. The extensive tests performed in this investigation show that the new transmission detector provides a stable and sensitive cumulative signal output and is suitable for beam monitoring during patient treatment.

Switching to aripiprazole in outpatients with schizophrenia experiencing insufficient efficacy and/or safety/tolerability issues with risperidone: a randomized, multicentre, open-label study.

PubMed

Ryckmans, V; Kahn, J P; Modell, S; Werner, C; McQuade, R D; Kerselaers, W; Lissens, J; Sanchez, R

2009-05-01

This study evaluated the safety/tolerability and effectiveness of aripiprazole titrated-dose versus fixed-dose switching strategies from risperidone in patients with schizophrenia experiencing insufficient efficacy and/or safety/tolerability issues. Patients were randomized to an aripiprazole titrated-dose (starting dose 5 mg/day) or fixed-dose (dose 15 mg/day) switching strategy with risperidone down-tapering. Primary endpoint was rate of discontinuation due to adverse events (AEs) during the 12-week study. Secondary endpoints included positive and negative syndrome scale (PANSS), clinical global impressions - improvement of illness scale (CGI-I), preference of medication (POM), subjective well-being under neuroleptics (SWN-K) and GEOPTE (Grupo Español para la Optimización del Tratamiento de la Esquizofrenia) scales. Rates of discontinuations due to AEs were similar between titrated-dose and fixed-dose strategies (3.5% vs. 5.0%; p=0.448). Improvements in mean PANSS total scores were similar between aripiprazole titrated-dose and fixed-dose strategies (-14.8 vs. -17.2; LOCF), as were mean CGI-I scores (2.9 vs. 2.8; p=0.425; LOCF) and SWN-K scores (+8.6 vs.+10.3; OC,+7.8 vs.+9.8; LOCF). Switching can be effectively and safely achieved through a titrated-dose or fixed-dose switching strategy for aripiprazole, with down-titration of risperidone.

SU-E-T-472: A Multi-Dimensional Measurements Comparison to Analyze a 3D Patient Specific QA Tool

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

Ashmeg, S; Jackson, J; Zhang, Y

Purpose: To quantitatively evaluate a 3D patient specific QA tool using 2D film and 3D Presage dosimetry. Methods: A brain IMRT case was delivered to Delta4, EBT2 film and Presage plastic dosimeter. The film was inserted in the solid water slabs at 7.5cm depth for measurement. The Presage dosimeter was inserted into a head phantom for 3D dose measurement. Delta4's Anatomy software was used to calculate the corresponding dose to the film in solid water slabs and to Presage in the head phantom. The results from Anatomy were compared to both calculated results from Eclipse and measured dose from filmmore » and Presage to evaluate its accuracy. Using RIT software, we compared the “Anatomy” dose to the EBT2 film measurement and the film measurement to ECLIPSE calculation. For 3D analysis, DICOM file of “Anatomy” was extracted and imported to CERR software, which was used to compare the Presage dose to both “Anatomy” calculation and ECLIPSE calculation. Gamma criteria of 3% - 3mm and 5% - 5mm was used for comparison. Results: Gamma passing rates of film vs “Anatomy”, “Anatomy” vs ECLIPSE and film vs ECLIPSE were 82.8%, 70.9% and 87.6% respectively when 3% - 3mm criteria is used. When the criteria is changed to 5% - 5mm, the passing rates became 87.8%, 76.3% and 90.8% respectively. For 3D analysis, Anatomy vs ECLIPSE showed gamma passing rate of 86.4% and 93.3% for 3% - 3mm and 5% - 5mm respectively. The rate is 77.0% for Presage vs ECLIPSE analysis. The Anatomy vs ECLIPSE were absolute dose comparison. However, film and Presage analysis were relative comparison Conclusion: The results show higher passing rate in 3D than 2D in “Anatomy” software. This could be due to the higher degrees of freedom in 3D than in 2D for gamma analysis.« less

A prospective randomized, double-dummy trial comparing IV push low dose ketamine to short infusion of low dose ketamine for treatment of  pain in the ED.

PubMed

Motov, Sergey; Mai, Mo; Pushkar, Illya; Likourezos, Antonios; Drapkin, Jefferson; Yasavolian, Matthew; Brady, Jason; Homel, Peter; Fromm, Christian

2017-08-01

Compare adverse effects and analgesic efficacy of low-dose ketamine for acute pain in the ED administered either by single intravenous push (IVP) or short infusion (SI). Patients 18-65, presenting to ED with acute abdominal, flank, or musculoskeletal pain with initial pain score≥5, were randomized to ketamine 0.3mg/kg by either IVP or SI with placebo double-dummy. Adverse effects were evaluated by Side Effects Rating Scale for Dissociative Anesthetics (SERSDA) and Richmond Agitation-Sedation Scale (RASS) at 5, 15, 30, 60, 90, and 120min post-administration; analgesic efficacy was evaluated by Numerical Rating Scale (NRS). 48 patients enrolled in the study. IVP group had higher overall rates of feeling of unreality on SERSDA scale: 92% versus 54% (difference 37.5%; p=0.008; 95% CI 9.3-59.5%). At 5min median severity of feeling of unreality was 3.0 for IVP versus 0.0 for SI (p=0.001). IVP also showed greater rates of sedation on RASS scale at 5min: median RASS -2.0 versus 0.0 (p=0.01). Decrease in mean pain scores from baseline to 15min was similar across groups: 5.2±3.53 (95% CI 3.7-6.7) for IVP; 5.75±3.48 (95% CI 4.3-7.2) for SI. There were no statistically significant differences with respect to changes in vital signs and need for rescue medication. Low-dose ketamine given as a short infusion is associated with significantly lower rates of feeling of unreality and sedation with no difference in analgesic efficacy in comparison to intravenous push. Copyright © 2017 Elsevier Inc. All rights reserved.

Four-dimensional dose distributions of step-and-shoot IMRT delivered with real-time tumor tracking for patients with irregular breathing: Constant dose rate vs dose rate regulation

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

Yang Xiaocheng; Han-Oh, Sarah; Gui Minzhi

2012-09-15

Purpose: Dose-rate-regulated tracking (DRRT) is a tumor tracking strategy that programs the MLC to track the tumor under regular breathing and adapts to breathing irregularities during delivery using dose rate regulation. Constant-dose-rate tracking (CDRT) is a strategy that dynamically repositions the beam to account for intrafractional 3D target motion according to real-time information of target location obtained from an independent position monitoring system. The purpose of this study is to illustrate the differences in the effectiveness and delivery accuracy between these two tracking methods in the presence of breathing irregularities. Methods: Step-and-shoot IMRT plans optimized at a reference phase weremore » extended to remaining phases to generate 10-phased 4D-IMRT plans using segment aperture morphing (SAM) algorithm, where both tumor displacement and deformation were considered. A SAM-based 4D plan has been demonstrated to provide better plan quality than plans not considering target deformation. However, delivering such a plan requires preprogramming of the MLC aperture sequence. Deliveries of the 4D plans using DRRT and CDRT tracking approaches were simulated assuming the breathing period is either shorter or longer than the planning day, for 4 IMRT cases: two lung and two pancreatic cases with maximum GTV centroid motion greater than 1 cm were selected. In DRRT, dose rate was regulated to speed up or slow down delivery as needed such that each planned segment is delivered at the planned breathing phase. In CDRT, MLC is separately controlled to follow the tumor motion, but dose rate was kept constant. In addition to breathing period change, effect of breathing amplitude variation on target and critical tissue dose distribution is also evaluated. Results: Delivery of preprogrammed 4D plans by the CDRT method resulted in an average of 5% increase in target dose and noticeable increase in organs at risk (OAR) dose when patient breathing is either 10% faster or slower than the planning day. In contrast, DRRT method showed less than 1% reduction in target dose and no noticeable change in OAR dose under the same breathing period irregularities. When {+-}20% variation of target motion amplitude was present as breathing irregularity, the two delivery methods show compatible plan quality if the dose distribution of CDRT delivery is renormalized. Conclusions: Delivery of 4D-IMRT treatment plans, stemmed from 3D step-and-shoot IMRT and preprogrammed using SAM algorithm, is simulated for two dynamic MLC-based real-time tumor tracking strategies: with and without dose-rate regulation. Comparison of cumulative dose distribution indicates that the preprogrammed 4D plan is more accurately and efficiently conformed using the DRRT strategy, as it compensates the interplay between patient breathing irregularity and tracking delivery without compromising the segment-weight modulation.« less

Hematopoietic responses under protracted exposures to low daily dose gamma irradiation

NASA Astrophysics Data System (ADS)

Seed, T. M.; Fritz, T. E.; Tolle, D. V.; Jackson, W. E.

In attempting to evaluate the possible health consequences of chronic ionizing radiation exposure during extended space travel (e.g., Mars Mission), ground-based experimental studies of the clinical and pathological responses of canines under low daily doses of 60Co gamma irradiation (0.3-26.3 cGy d -1) have been examined. Specific reference was given to responses of the blood forming system. Results suggest that the daily dose rate of 7.5 cGy d -1 represents a threshold below which the hematopoietic system can retain either partial or full trilineal cell-producing capacity (erythropoiesis, myelopoiesis, and megakaryopoiesis) for extended periods of exposure (> 1yr). Trilineal capacity was fully retained for several years of exposure at the lowest dose-rate tested (0.3 cGy d -1) but was completely lost within several hundred days at the highest dose-rate (26.3 cGy d -1). Retention of hematopoietic capacity under chronic exposure has been demonstrated to be mediated by hematopoietic progenitors with acquired radioresistance and repair functions, altered cytogenetics, and cell-cycle characteristics. Radiological, biological, and temporal parameters responsible for these vital acquisitions by hematopoietic progenitors have been partially characterized. These parameters, along with threshold responses, are described and discussed in relation to potential health risks of the space traveler under chronic stress of low-dose irradiation.

Dose-volume histogram analysis of brainstem necrosis in head and neck tumors treated using carbon-ion radiotherapy.

PubMed

Shirai, Katsuyuki; Fukata, Kyohei; Adachi, Akiko; Saitoh, Jun-Ichi; Musha, Atsushi; Abe, Takanori; Kanai, Tatsuaki; Kobayashi, Daijiro; Shigeta, Yuka; Yokoo, Satoshi; Chikamatsu, Kazuaki; Ohno, Tatsuya; Nakano, Takashi

2017-10-01

We aimed to evaluate the relationship between brainstem necrosis and dose-volume histograms in patients with head and neck tumors after carbon-ion radiotherapy. We evaluated 85 patients with head and neck tumors who underwent carbon-ion radiotherapy and were followed-up for ≥12months. Brainstem necrosis was evaluated using the Common Terminology Criteria for Adverse Events (version 4.0). The median follow-up was 24months, and four patients developed grade 1 brainstem necrosis, with 2-year and 3-year cumulative rates of 2.8% and 6.5%, respectively. Receiver operating characteristic curve analysis revealed the following significant cut-off values: a maximum brainstem dose of 48Gy (relative biological effectiveness [RBE]), D1cm 3 of 27Gy (RBE), V40Gy (RBE) of 0.1cm 3 , V30Gy (RBE) of 0.7cm 3 , and V20Gy (RBE) of 1.4cm 3 . Multivariate analysis revealed that V30Gy (RBE) was most significantly associated with brainstem necrosis. The 2-year cumulative rates were 33% and 0% for V30Gy (RBE) of ≥0.7cm 3 and <0.7cm 3 , respectively (p<0.001). The present study indicated that the dose constraints might help minimize brainstem necrosis after carbon-ion radiotherapy. Copyright © 2017 The Author(s). Published by Elsevier B.V. All rights reserved.

Better retention of Malaysian opiate dependents treated with high dose methadone in methadone maintenance therapy

PubMed Central

2010-01-01

Background Methadone is a synthetic opiate mu receptor agonist that is widely used to substitute for illicit opiates in the management of opiate dependence. It helps prevent opiate users from injecting and sharing needles which are vehicles for the spread of HIV and other blood borne viruses. This study has the objective of determining the utility of daily methadone dose to predict retention rates and re-injecting behaviour among opiate dependents. Methods Subjects comprised opiate dependent individuals who met study criteria. They took methadone based on the Malaysian guidelines and were monitored according to the study protocols. At six months, data was collected for analyses. The sensitivity and specificity daily methadone doses to predict retention rates and re-injecting behaviour were evaluated. Results Sixty-four patients volunteered to participate but only 35 (54.69%) remained active and 29 (45.31%) were inactive at 6 months of treatment. Higher doses were significantly correlated with retention rate (p < 0.0001) and re-injecting behaviour (p < 0.001). Of those retained, 80.0% were on 80 mg or more methadone per day doses with 20.0% on receiving 40 mg -79 mg. Conclusions We concluded that a daily dose of at least 40 mg was required to retain patients in treatment and to prevent re-injecting behaviour. A dose of at least 80 mg per day was associated with best results. PMID:21167035

Impact of West Nile virus dose and incubation period on vector competence of Culex nigripalpus (Diptera: Culicidae).

PubMed

Richards, Stephanie L; Anderson, Sheri L; Lord, Cynthia C; Tabachnick, Walter J

2011-11-01

Female Culex nigripalpus were fed blood containing a low dose (6.3±0.01 logs plaque-forming units (PFU)/mL) or high dose (7.3±0.1 logs PFU/mL) of West Nile virus (WNV) and maintained at 28°C for incubation periods (IPs) of 6 or 12 days. Vector competence was measured using rates of infection (% with WNV-positive bodies), dissemination (% infected with WNV-positive legs), and transmission (% infected with WNV-positive saliva). Infection rates were not influenced by dose or IP. Dissemination rates were significantly higher at the high dose, and this was dependent on IP. Despite 100% infection and 90% dissemination in the most permissive treatment of high dose and 12 days, only 11% transmission was observed. Virus titers in body and leg tissues were significantly lower at the low dose and the titers were not influenced by IP. We show that not all mosquitoes with infections and/or disseminated infections transmit WNV under the conditions of this test. Therefore, characterizing the transmission ability of a vector population using infection or dissemination as indicators of transmission may provide inaccurate information. The complex relationships between infection, dissemination, and transmission must be evaluated under a variety of biological and environmental conditions to begin to assess the epidemiological risk of natural mosquito populations.

Radiation dose to patients and image quality evaluation from coronary 256-slice computed tomographic angiography

NASA Astrophysics Data System (ADS)

Chen, Liang-Kuang; Wu, Tung-Hsin; Yang, Ching-Ching; Tsai, Chia-Jung; Lee, Jason J. S.

2010-07-01

The aim of this study is to assess radiation dose and the corresponding image quality from suggested CT protocols which depends on different mean heart rate and high heart rate variability by using 256-slice CT. Fifty consecutive patients referred for a cardiac CT examination were included in this study. All coronary computed tomographic angiography (CCTA) examinations were performed on a 256-slice CT scanner with one of five different protocols: retrospective ECG-gating (RGH) with full dose exposure in all R-R intervals (protocol A), RGH of 30-80% pulsing window with tube current modulation (B), RGH of 78±5% pulsing window with tube current modulation (C), prospective ECG-triggering (PGT) of 78% R-R interval with 5% padding window (D) and PGT of 78% R-R interval without padding window (E). Radiation dose parameters and image quality scoring were determined and compared. In this study, no significant differences were found in comparison on image quality of the five different protocols. Protocol A obtained the highest radiation dose comparing with those of protocols B, C, D and E by a factor of 1.6, 2.4, 2.5 and 4.3, respectively ( p<0.001), which were ranged between 2.7 and 11.8 mSv. The PGT could significantly reduce radiation dose delivered to patients, as compared to the RGH. However, the use of PGT has limitations and is only good in assessing cases with lower mean heart rate and stable heart rate variability. With higher mean heart rate and high heart rate variability circumstances, the RGH within 30-80% of R-R interval pulsing window is suggested as a feasible technique for assessing diagnostic performance.

Characterization of the radiation environment for a large-area interim spent-nuclear-fuel storage facility

NASA Astrophysics Data System (ADS)

Fortkamp, Jonathan C.

Current needs in the nuclear industry and movements in the political arena indicate that authorization may soon be given for development of a federal interim storage facility for spent nuclear fuel. The initial stages of the design work have already begun within the Department of Energy and are being reviewed by the Nuclear Regulatory Commission. This dissertation addresses the radiation environment around an interim spent nuclear fuel storage facility. Specifically the dissertation characterizes the radiation dose rates around the facility based on a design basis source term, evaluates the changes in dose due to varying cask spacing configurations, and uses these results to define some applicable health physics principles for the storage facility. Results indicate that dose rates from the facility are due primarily from photons from the spent fuel and Co-60 activation in the fuel assemblies. In the modeled cask system, skyshine was a significant contribution to dose rates at distances from the cask array, but this contribution can be reduced with an alternate cask venting system. With the application of appropriate health physics principles, occupation doses can be easily maintained far below regulatory limits and maintained ALARA.

Health Physics Society Comments to U.S. Environmental Protection Agency Regulatory Reform Task Force.

PubMed

Ring, Joseph; Tupin, Edward; Elder, Deirdre; Hiatt, Jerry; Sheetz, Michael; Kirner, Nancy; Little, Craig

2018-05-01

The Health Physics Society (HPS) provided comment to the U.S. Environmental Protection Agency (EPA) on options to consider when developing an action plan for President Trump's Executive Order to evaluate regulations for repeal, replacement, or modification. The HPS recommended that the EPA reconsider their adherence to the linear no-threshold (LNT) model for radiation risk calculations and improve several documents by better addressing uncertainties in low-dose, low dose-rate (LDDR) radiation exposure environments. The authors point out that use of the LNT model near background levels cannot provide reliable risk projections, use of the LNT model and collective-dose calculations in some EPA documents is inconsistent with the recommendations of international organizations, and some EPA documents have not been exposed to the public comment rule-making process. To assist in establishing a better scientific basis for the risks of low dose rate and low dose radiation exposure, the EPA should continue to support the "Million Worker Study," led by the National Council on Radiation Protection and Measurement.

Evaluating the risk of death via the hematopoietic syndrome mode for prolonged exposure of nuclear workers to radiation delivered at very low rates.

PubMed

Scott, B R; Lyzlov, A F; Osovets, S V

1998-05-01

During a Phase-I effort, studies were planned to evaluate deterministic (nonstochastic) effects of chronic exposure of nuclear workers at the Mayak atomic complex in the former Soviet Union to relatively high levels (> 0.25 Gy) of ionizing radiation. The Mayak complex has been used, since the late 1940's, to produce plutonium for nuclear weapons. Workers at Site A of the complex were involved in plutonium breeding using nuclear reactors, and some were exposed to relatively large doses of gamma rays plus relatively small neutron doses. The Weibull normalized-dose model, which has been set up to evaluate the risk of specific deterministic effects of combined, continuous exposure of humans to alpha, beta, and gamma radiations, is here adapted for chronic exposure to gamma rays and neutrons during repeated 6-h work shifts--as occurred for some nuclear workers at Site A. Using the adapted model, key conclusions were reached that will facilitate a Phase-II study of deterministic effects among Mayak workers. These conclusions include the following: (1) neutron doses may be more important for Mayak workers than for Japanese A-bomb victims in Hiroshima and can be accounted for using an adjusted dose (which accounts for neutron relative biological effectiveness); (2) to account for dose-rate effects, normalized dose X (a dimensionless fraction of an LD50 or ED50) can be evaluated in terms of an adjusted dose; (3) nonlinear dose-response curves for the risk of death via the hematopoietic mode can be converted to linear dose-response curves (for low levels of risk) using a newly proposed dimensionless dose, D = X(V), in units of Oklad (where D is pronounced "deh"), and V is the shape parameter in the Weibull model; (4) for X < or = Xo, where Xo is the threshold normalized dose, D = 0; (5) unlike absorbed dose, the dose D can be averaged over different Mayak workers in order to calculate the average risk of death via the hematopoietic mode for the population exposed at Site A; and (6) the expected cases of death via the hematopoietic syndrome mode for Mayak workers chronically exposed during work shifts at Site A to gamma rays and neutrons can be predicted using ln(2)B M[D]; where B (pronounced "beh") is the number of workers at risk (criticality accident victims excluded); and M[D] is the average (mean) value of D (averaged over the worker population at risk, for Site A, for the time period considered). These results can be used to facilitate a Phase II study of deterministic radiation effects among Mayak workers chronically exposed to gamma rays and neutrons.

Multicentre evaluation of a novel vaginal dose reporting method in 153 cervical cancer patients.

PubMed

Westerveld, Henrike; de Leeuw, Astrid; Kirchheiner, Kathrin; Dankulchai, Pittaya; Oosterveld, Bernard; Oinam, Arun; Hudej, Robert; Swamidas, Jamema; Lindegaard, Jacob; Tanderup, Kari; Pötter, Richard; Kirisits, Christian

2016-09-01

Recently, a vaginal dose reporting method for combined EBRT and BT in cervical cancer patients was proposed. The current study was to evaluate vaginal doses with this method in a multicentre setting, wherein different applicators, dose rates and protocols were used. In a subset of patients from the EMBRACE study, vaginal doses were evaluated. Doses at the applicator surface left/right and anterior/posterior and at 5mm depth were measured. In addition, the dose at the Posterior-Inferior Border of Symphysis (PIBS) vaginal dose point and PIBS±2cm, corresponding to the mid and lower vagina, was measured. 153 patients from seven institutions were included. Large dose variations expressed in EQD2 with α/β=3Gy were seen between patients, in particular at the top left and right vaginal wall (median 195 (range 61-947)Gy/178 (61-980)Gy, respectively). At 5mm depth, doses were 98 (55-212)Gy/91 (54-227)Gy left/right, and 71 (51-145)Gy/67 (49-189)Gy anterior/posterior, respectively. The dose at PIBS and PIBS±2cm was 41 (3-81)Gy, 54 (32-109)Gy and 5 (1-51)Gy, respectively. At PIBS+2cm (mid vagina) dose variation was coming from BT. The variation at PIBS-2cm (lower vagina) was mainly dependent on EBRT field border location. This novel method for reporting vaginal doses coming from EBRT and BT through well-defined dose points gives a robust representation of the dose along the vaginal axis. In addition, it allows comparison of vaginal dose between patients from different centres. The doses at the PIBS points represent the doses at the mid and lower parts of the vagina. Large variations in dose throughout the vagina were observed between patients and centres. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Needle migration and dosimetric impact in high-dose-rate brachytherapy for prostate cancer evaluated by repeated MRI.

PubMed

Buus, Simon; Lizondo, Maria; Hokland, Steffen; Rylander, Susanne; Pedersen, Erik M; Tanderup, Kari; Bentzen, Lise

To quantify needle migration and dosimetric impact in high-dose-rate brachytherapy for prostate cancer and propose a threshold for needle migration. Twenty-four high-risk prostate cancer patients treated with an HDR boost of 2 × 8.5 Gy were included. Patients received an MRI for planning (MRI1), before (MRI2), and after treatment (MRI3). Time from needle insertion to MRI3 was ∼3 hours. Needle migration was evaluated from coregistered images: MRI1-MRI2 and MRI1-MRI3. Dose volume histogram parameters from the treatment plan based on MRI1 were related to parameters based on needle positions in MRI2 or MRI3. Regression was used to model the average needle migration per implant and change in D90 clinical target volume, CTV prostate+3mm . The model fit was used for estimating the dosimetric impact in equivalent dose in 2 Gy fractions for dose levels of 6, 8.5, 10, 15, and 19 Gy. Needle migration was on average 2.2 ± 1.8 mm SD from MRI1-MRI2 and 5.0 ± 3.0 mm SD from MRI1-MRI3. D90 CTV prostate+3mm was robust toward average needle migration ≤3 mm, whereas for migration >3 mm D90 decreased by 4.5% per mm. A 3 mm of needle migration resulted in a decrease of 0.9, 1.7, 2.3, 4.8, and 7.6 equivalent dose in 2 Gy fractions for dose levels of 6, 8.5, 10, 15, and 19 Gy, respectively. Substantial needle migration in high-dose-rate brachytherapy occurs frequently in 1-3 hours following needle insertion. A 3-mm threshold of needle migration is proposed, but 2 mm may be considered for dose levels ≥15 Gy. Copyright © 2017 American Brachytherapy Society. Published by Elsevier Inc. All rights reserved.

MAGAT gel and EBT2 film‐based dosimetry for evaluating source plugging‐based treatment plan in Gamma Knife stereotactic radiosurgery

PubMed Central

Vivekanandhan, S.; Kale, S.S.; Rath, G.K.; Senthilkumaran, S.; Thulkar, S.; Subramani, V.; Laviraj, M.A.; Bisht, R.K.; Mahapatra, A.K.

2012-01-01

This work illustrates a procedure to assess the overall accuracy associated with Gamma Knife treatment planning using plugging. The main role of source plugging or blocking is to create dose falloff in the junction between a target and a critical structure. We report the use of MAGAT gel dosimeter for verification of an experimental treatment plan based on plugging. The polymer gel contained in a head‐sized glass container simulated all major aspects of the treatment process of Gamma Knife radiosurgery. The 3D dose distribution recorded in the gel dosimeter was read using a 1.5T MRI scanner. Scanning protocol was: CPMG pulse sequence with 8 equidistant echoes, TR=7 s, echo step=14 ms, pixel size=0.5 mm x 0.5 mm, and slice thickness of 2 mm. Using a calibration relationship between absorbed dose and spin‐spin relaxation rate (R2), we converted R2 images to dose images. Volumetric dose comparison between treatment planning system (TPS) and gel measurement was accomplished using an in‐house MATLAB‐based program. The isodose overlay of the measured and computed dose distribution on axial planes was in close agreement. Gamma index analysis of 3D data showed more than 94% voxel pass rate for different tolerance criteria of 3%/2 mm, 3%/1 mm and 2%/2 mm. Film dosimetry with GAFCHROMIC EBT 2 film was also performed to compare the results with the calculated TPS dose. Gamma index analysis of film measurement for the same tolerance criteria used for gel measurement evaluation showed more than 95% voxel pass rate. Verification of gamma plan calculated dose on account of shield is not part of acceptance testing of Leksell Gamma Knife (LGK). Through this study we accomplished a volumetric comparison of dose distributions measured with a polymer gel dosimeter and Leksell GammaPlan (LGP) calculations for plans using plugging. We propose gel dosimeter as a quality assurance (QA) tool for verification of plug‐based planning. PACS number: 87.53.Ly, 87.55.‐x, 87.56.N‐ PMID:23149780

Single point estimation of phenytoin dosing: a reappraisal.

PubMed

Koup, J R; Gibaldi, M; Godolphin, W

1981-11-01

A previously proposed method for estimation of phenytoin dosing requirement using a single serum sample obtained 24 hours after intravenous loading dose (18 mg/Kg) has been re-evaluated. Using more realistic values for the volume of distribution of phenytoin (0.4 to 1.2 L/Kg), simulations indicate that the proposed method will fail to consistently predict dosage requirements. Additional simulations indicate that two samples obtained during the 24 hour interval following the iv loading dose could be used to more reliably predict phenytoin dose requirement. Because of the nonlinear relationship which exists between phenytoin dose administration rate (RO) and the mean steady state serum concentration (CSS), small errors in prediction of the required RO result in much larger errors in CSS.

Low-dose levodopa therapy in Japanese patients with Parkinson's disease: a retrospective study.

PubMed

Kitagawa, Mayumi; Tashiro, Kunio

2005-09-01

To investigate the efficacy and the rate of adverse events of chronic low-dose levodopa-carbidopa therapy in Japanese patients with Parkinson's disease (PD). A total of 92 Japanese PD patients treated with low doses of levodopa from the outset were studied. Both disease-specific motor disabilities and quality of life (QOL) in the patients were evaluated using the Unified Parkinson's Disease Rating Scale (UPDRS) and the Parkinson's Disease 39 Quality of Life Questionnaire (PDQ39), respectively. In the overall patient group, the mean duration of treatment, the mean daily dose of levodopa, the disability scores and the motor scores of UPDRS were 6.2 years, 186.4 mg, 8.0 and 19.2, respectively. The rates of motor fluctuations, dyskinesias and hallucinations were 8.7%, 6.5% and 14.1%, respectively. The mean summary index of PDQ39 scores was 23.1. Patients with motor fluctuations showed a significantly earlier disease onset. Dose of levodopa, age at onset, and treatment duration were not associated with the occurrence of dyskinesias. Patients with hallucination had higher doses of levodopa and dopamine agonist. Our results demonstrate that chronic administration of a low-dose levodopa preparation can provide satisfactory benefit with a low incidence of motor complications, and can result in good QOL in Japanese patients with PD. The concomitant use of a small amount of dopamine agonist and amantadine from the outset has partly contributed to a reduced dose of levodopa and the lesser occurrence of motor complications.

Radioinduced changes in respiration, organoleptic properties, weight, flesh firmness, and surface color of apple fruits during controlled atmosphere (CA) storage

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

Okamoto, T.; Harata, J.; Osanai, T.

1972-03-01

Jonathan apples were irradiated with /sup 60/Co gamma rays, with doses of 0 (control), 5, 50 and 200 Krad (dose rate: 100 Krad/hr), stored for 6.0 months in a CA room (oxygen 3%, carbon dioxide 3%) at 0 deg C and analyzed. No significant differences between irradiated and unirradiated apples in changes of weight, flesh age under CA conditions at 0 deg C. The irradiation of apple fruits with a dose of 200 Krad lowered their qualities in respect to respiration and organoleptic properties. Apples irradiated with a dose of 5 Krad, however, showed the lowest respiration rate and keptmore » superior qualities which were evaluated by organoleptic tests. According to the above results, the irradiation with 5 Krad may be recommended as the pretreatment of CA storage of apple fruite. (auth)« less

Evaluation of scattered radiation emitted from X-ray security scanners on occupational dose to airport personnel

NASA Astrophysics Data System (ADS)

Dalah, Entesar; Fakhry, Angham; Mukhtar, Asma; Al Salti, Farah; Bader, May; Khouri, Sara; Al-Zahmi, Reem

2017-06-01

Based on security issues and regulations airports are provided with luggage cargo scanners. These scanners utilize ionizing radiation that in principle present health risks toward humans. The study aims to investigate the amount of backscatter produced by passenger luggage and cargo toward airport personnel who are located at different distances from the scanners. To approach our investigation a Thermo Electron Radeye-G probe was used to quantify the backscattered radiation measured in terms of dose-rate emitted from airport scanners, Measurements were taken at the entrance and exit positions of the X-ray tunnel at three different distances (0, 50, and 100 cm) for two different scanners; both scanners include shielding curtains that reduce scattered radiation. Correlation was demonstrated using the Pearson coefficient test. Measurements confirmed an inverse relationship between dose rate and distance. An estimated occupational accumulative dose of 0.88 mSv/y, and 2.04 mSv/y were obtained for personnel working in inspection of carry-on, and cargo, respectively. Findings confirm that the projected dose of security and engineering staff are being well within dose limits.

Reprint of 'Evaluation of Scattered Radiation Emitted From X-ray Security Scanners on Occupational Dose to Airport Personnel'

NASA Astrophysics Data System (ADS)

Dalah, Entesar; Fakhry, Angham; Mukhtar, Asma; Al Salti, Farah; Bader, May; Khouri, Sara; Al-Zahmi, Reem

2017-11-01

Based on security issues and regulations airports are provided with luggage cargo scanners. These scanners utilize ionizing radiation that in principle present health risks toward humans. The study aims to investigate the amount of backscatter produced by passenger luggage and cargo toward airport personnel who are located at different distances from the scanners. To approach our investigation a Thermo Electron Radeye-G probe was used to quantify the backscattered radiation measured in terms of dose-rate emitted from airport scanners, Measurements were taken at the entrance and exit positions of the X-ray tunnel at three different distances (0, 50, and 100 cm) for two different scanners; both scanners include shielding curtains that reduce scattered radiation. Correlation was demonstrated using the Pearson coefficient test. Measurements confirmed an inverse relationship between dose rate and distance. An estimated occupational accumulative dose of 0.88 mSv/y, and 2.04 mSv/y were obtained for personnel working in inspection of carry-on, and cargo, respectively. Findings confirm that the projected dose of security and engineering staff are being well within dose limits.

Dose Escalation of Whole-Brain Radiotherapy for Brain Metastases From Melanoma

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

Rades, Dirk, E-mail: Rades.Dirk@gmx.ne; Heisterkamp, Christine; Huttenlocher, Stefan

2010-06-01

Purpose: The majority of patients with brain metastases from melanoma receive whole-brain radiotherapy (WBRT). However, the results are poor. Hypofractionation regimens failed to improve the outcome of these patients. This study investigates a potential benefit from escalation of the WBRT dose beyond the 'standard' regimen 30 Gy in 10 fractions (10x3 Gy). Methods and Materials: Data from 51 melanoma patients receiving WBRT alone were retrospectively analyzed. A dosage of 10x3 Gy (n = 33) was compared with higher doses including 40 Gy/20 fractions (n = 11) and 45 Gy/15 fractions (n = 7) for survival (OS) and local (intracerebral) controlmore » (LC). Additional potential prognostic factors were evaluated: age, gender, performance status, number of metastases, extracerebral metastases, and recursive partitioning analysis (RPA) class. Results: At 6 months, OS rates were 27% after 10x3 Gy and 50% after higher doses (p = 0.009). The OS rates at 12 months were 4% and 20%. On multivariate analysis, higher WBRT doses (p = 0.010), fewer than four brain metastases (p = 0.012), no extracerebral metastases (p = 0.006), and RPA class 1 (p = 0.005) were associated with improved OS. The LC rates at 6 months were 23% after 10x3 Gy and 50% after higher doses (p = 0.021). The LC rates at 12 months were 0% and 13%. On multivariate analysis, higher WBRT doses (p = 0.020) and fewer than brain metastases (p = 0.002) were associated with better LC. Conclusions: Given the limitations of a retrospective study, the findings suggest that patients with brain metastases from melanoma receiving WBRT alone may benefit from dose escalation beyond 10x3 Gy. The hypothesis generated by this study must be confirmed in a randomized trial stratifying for significant prognostic factors.« less

Physiological responses to glyphosate are dependent on Eucalyptus urograndis genotype

USDA-ARS?s Scientific Manuscript database

Two experiments were conducted to evaluate the response of Eucalyptus urograndis genotypes (C219 and GG100) to glyphosate in growth chambers. As glyphosate dose increased (18 up to 720 g ae ha-1), CO2 assimilation rate, transpiration rate, and stomatal conductance decreased fastest and strongest in ...

Development and Evaluation of a New Air Exchange Rate Algorithm for the Stochastic Human Exposure and Dose Simulation Model (ISES Presentation)

EPA Science Inventory

Previous exposure assessment panel studies have observed considerable seasonal, between-home and between-city variability in residential pollutant infiltration. This is likely a result of differences in home ventilation, or air exchange rates (AER). The Stochastic Human Exposure ...

Failed heart rate control with oral metoprolol prior to coronary CT angiography: effect of additional intravenous metoprolol on heart rate, image quality and radiation dose.

PubMed

Jiménez-Juan, Laura; Nguyen, Elsie T; Wintersperger, Bernd J; Moshonov, Hadas; Crean, Andrew M; Deva, Djeven P; Paul, Narinder S; Torres, Felipe S

2013-01-01

The purpose of this study was to evaluate the effect of intravenous (i.v.) metoprolol after a suboptimal heart rate (HR) response to oral metoprolol (75-150 mg) on HR control, image quality (IQ) and radiation dose during coronary CTA using 320-MDCT. Fifty-three consecutive patients who failed to achieve a target HR of < 60 bpm after an oral dose of metoprolol and required supplementary i.v. metoprolol (5-20 mg) prior to coronary CTA were evaluated. Patients with HR < 60 bpm during image acquisition were defined as responders (R) and those with HR ≥ 60 bpm as non-responders (NR). Two observers assessed IQ using a 3-point scale (1-2, diagnostic and 3, non-diagnostic). Effective dose (ED) was estimated using dose-length product and a 0.014 mSV/mGy.cm conversion factor. Baseline characteristics and HR on arrival were similar in the two groups. 58% of patients didn't achieve the target HR after receiving i.v. metoprolol (NR). R had a significantly higher HR reduction after oral (mean HR 63.9 ± 4.5 bpm vs. 69.6 ± 5.6 bpm) (p < 0.005) and i.v. (mean HR 55.4 ± 3.9 bpm vs. 67.4 ± 5.3 bpm) (p < 0.005) doses of metoprolol. Studies from NR showed a significantly higher ED in comparison to R (8.0 ± 2.9 vs. 6.1 ± 2.2 mSv) (p = 0.016) and a significantly higher proportion of non-diagnostic coronary segments (9.2 vs. 2.5%) (p < 0.001). 58% of patients who do not achieve a HR of <60 bpm prior to coronary CTA with oral fail to respond to additional i.v. metoprolol and have studies with higher radiation dose and worse image quality.

High-dose-rate stereotactic body radiation therapy for postradiation therapy locally recurrent prostatic carcinoma: Preliminary prostate-specific antigen response, disease-free survival, and toxicity assessment.

PubMed

Fuller, Donald B; Wurzer, James; Shirazi, Reza; Bridge, Stephen S; Law, Jonathan; Mardirossian, George

2015-01-01

Patients with locally recurrent adenocarcinoma of the prostate following radiation therapy (RT) present a challenging problem. We prospectively evaluated the use of "high-dose-rate-like" prostate stereotactic body RT (SBRT) salvage for this circumstance, evaluating prostate-specific antigen response, disease-free survival, and toxicity. Between February 2009 and March 2014, 29 patients with biopsy-proven recurrent locally prostate cancer >2 years post-RT were treated. Median prior RT dose was 73.8 Gy and median interval to SBRT salvage was 88 months. Median recurrence Gleason score was 7 (79% was ≥7). Pre-existing RT toxicity >grade 1 was a reason for exclusion. Magnetic resonance imaging-defined prostate volume including any suspected extraprostatic extension, comprising the planning target volume. A total of 34 Gy/5 fractions was given, delivering a heterogeneous, high-dose-rate-like dose-escalation pattern. Toxicities were assessed using Common Terminology Criteria for Adverse Events, version 3.0, criteria. Twenty-nine treated patients had a median 24-month follow-up (range, 3-60 months). A median pre-SBRT salvage baseline prostate-specific antigen level of 3.1 ng/mL decreased to 0.65 ng/mL and 0.16 ng/mL at 1 and 2 years, respectively. Actuarial 2-year biochemical disease-free survival measured 82%, with no local failures. Toxicity >grade 1 was limited to the genitourinary domain, with 18% grade 2 or higher and 7% grade 3 or higher. No gastrointestinal toxicity >grade 1 occurred. Two-year disease-free survival is encouraging, and the prostate-specific antigen response kinetic appears comparable with that seen in de novo patients treated with SBRT, albeit still a preliminary finding. Grade ≥2 genitourinary toxicity was occasionally seen with no obvious predictive factor. Noting that our only brachytherapy case was 1 of the 2 cases with ≥grade 3 genitourinary toxicity, caution is recommended treating these patients. SBRT salvage of post-RT local recurrence appears clinically feasible, with longer term evaluation required to assess ultimate efficacy and late toxicity rates. Copyright © 2015 American Society for Radiation Oncology. Published by Elsevier Inc. All rights reserved.

Evaluation of dose-response relationship between smoking load and cardiopulmonary fitness in adult smokers: A cross-sectional study.

PubMed

Lauria, V T; Sperandio, E F; de Sousa, T L W; de Oliveira Vieira, W; Romiti, M; de Toledo Gagliardi, A R; Arantes, R L; Dourado, V Z

To evaluate the dose-response relationship between smoking load and cardiopulmonary fitness, as measured with cardiopulmonary exercise testing (CPET), in adult smokers free of respiratory diseases. After a complete clinical evaluation and spirometry, 95 adult smokers (35 men and 60 women) underwent CPET on a treadmill. The physiological responses during CPET showed lower cardiorespiratory fitness levels, regardless of smoking load, with a peak [Formula: see text] lower than 100% of the expected value and a lower maximum heart rate. We observed a significant moderate negative correlation between smoking load and peak [Formula: see text] . The smoking load also presented a significant negative correlation with maximum heart rate(r=-0.36; p<0.05), lactate threshold(r=-0.45; p<0.05), and peak ventilation(r=-0.43; p<0.05). However, a dose-response relationship between smoking load quartiles and cardiopulmonary fitness was not found comparing quartiles of smoking loads after adjustment for age, sex and cardiovascular risk. There appears to be no dose-response relationship between SL and cardiopulmonary fitness in adult smokers with preserved pulmonary function, after adjusting the analysis for age and cardiovascular risk. Our results suggest that smoking cessation might be useful as the primary strategy to prevent cardiopulmonary fitness decline in smokers, regardless of smoking load. Thus, even a very low dose of tobacco use must be avoided in preventive strategies focusing on becoming people more physically active and fit. Copyright © 2016 Sociedade Portuguesa de Pneumologia. Published by Elsevier España, S.L.U. All rights reserved.

Implementation of IMRT and VMAT using Delta4 phantom and portal dosimetry as dosimetry verification tools

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

Daci, Lulzime, E-mail: lulzime.daci@nodlandssykehuset.no; Malkaj, Partizan, E-mail: malkaj-p@hotmail.com

2016-03-25

In this study we analyzed and compared the dose distribution of different IMRT and VMAT plans with the intent to provide pre-treatment quality assurance using two different tools. Materials/Methods: We have used the electronic portal imaging device EPID after calibration to dose and correction for the background offset signal and also the Delta4 phantom after en evaluation of angular sensitivity. The Delta4 phantom has a two-dimensional array with ionization chambers. We analyzed three plans for each anatomical site calculated by Eclipse treatment planning system. The measurements were analyzed using γ-evaluation method with passing criteria 3% absolute dose and 3 mm distancemore » to agreement (DTA). For all the plans the range of score has been from 97% to 99% for gantry fixed at 0° while for rotational planes there was a slightly decreased pass rates and above 95%. Point measurement with a ionization chamber were done in additional to see the accuracy of portal dosimetry and to evaluate the Delta4 device to various dose rates. Conclusions: Both Delt4 and Portal dosimetry shows good results between the measured and calculated doses. While Delta4 is more accurate in measurements EPID is more time efficient. We have decided to use both methods in the first steps of IMRT and VMAT implementation and later on to decide which of the tools to use depending on the complexity of plans, how much accurate we want to be and the time we have on the machine.« less

Mating competitiveness of male Anopheles arabiensis mosquitoes irradiated with a partially or fully sterilizing dose in small and large laboratory cages.

PubMed

Helinski, M E H; Knols, B G J

2008-07-01

Male mating competitiveness is a crucial parameter in many genetic control programs including the sterile insect technique (SIT). We evaluated competitiveness of male Anopheles arabiensis Patton as a function of three experimental variables: (1) small or large cages for mating, (2) the effects of either a partially sterilizing (70 Gy) or fully sterilizing (120 Gy) dose, and (3) pupal or adult irradiation. Irradiated males competed for females with an equal number of unirradiated males. Competitiveness was determined by measuring hatch rates of individually laid egg batches. In small cages, pupal irradiation with the high dose resulted in the lowest competitiveness, whereas adult irradiation with the low dose gave the highest, with the latter males being equal in competitiveness to unirradiated males. In the large cage, reduced competitiveness of males irradiated in the pupal stage was more pronounced compared with the small cage; the males irradiated as adults at both doses performed similarly to unirradiated males. Unexpectedly, males irradiated with the high dose performed better in a large cage than in a small one. A high proportion of intermediate hatch rates was observed for eggs collected in the large cage experiments with males irradiated at the pupal stage. It is concluded that irradiation of adult An. arabiensis with the partially sterilizing dose results in the highest competitiveness for both cage designs. Cage size affected competitiveness for some treatments; therefore, competitiveness determined in laboratory experiments must be confirmed by releases into simulated field conditions. The protocols described are readily transferable to evaluate male competitiveness for other genetic control techniques.

Evaluation of rotigotine transdermal patch for the treatment of apathy and motor symptoms in Parkinson's disease.

PubMed

Hauser, Robert A; Slawek, Jaroslaw; Barone, Paolo; Dohin, Elisabeth; Surmann, Erwin; Asgharnejad, Mahnaz; Bauer, Lars

2016-06-07

This multicenter, double-blind, placebo-controlled study assessed the efficacy of rotigotine transdermal patch on apathy and motor symptoms in patients with Parkinson's disease (PD). Patients with PD-associated apathy (Unified Parkinson's Disease Rating Scale [UPDRS] I item 4 [motivation] ≥2 and patient-rated Apathy Scale [AS] ≥14) were randomized 1:1:1 to "low-dose" rotigotine (≤6 mg/24 h for early PD [those not receiving levodopa] or ≤8 mg/24 h for advanced PD [those receiving levodopa]), "high-dose" rotigotine (≤8 mg/24 h for early PD or ≤16 mg/24 h for advanced PD), or placebo, and maintained at optimal/maximal dose for 12 weeks. Coprimary efficacy variables were: change from baseline to End of Maintenance in patient-rated AS and UPDRS II + III total score. Recruitment was stopped after an interim futility analysis; therefore, all p values are exploratory. Of 122 patients randomized, 81.1 % completed the study (placebo, n = 32/40 [80.0 %]; low-dose rotigotine, n = 30/41 [73.2 %]; high-dose rotigotine, n = 37/41 [90.2 %]). No treatment difference was observed in the change in patient-rated AS (least squares mean [95 % confidence interval (CI)] difference: low-dose, 0.04 [-2.42, 2.50], p =0.977; high-dose, -0.22 [-2.61, 2.18], p = 0.859). Rotigotine improved UPDRS II + III total scores versus placebo (least squares mean [95 % CI] treatment difference: low-dose, -7.29 [-12.30, -2.28], p = 0.005; high-dose, -6.06 [-10.90, -1.21], p = 0.015), and the "mood/apathy" domain of the Non-Motor Symptom Scale as rated by the investigator (secondary outcome). The most frequent adverse events in rotigotine-treated patients were application site reactions, somnolence, and nausea. Rotigotine did not improve PD-associated apathy as rated by the patient but provided clinically relevant improvement in motor control and activities of daily living. ClinicalTrials.gov identifier NCT01782222 . Trial registration date: January 30, 2013.

Real-time tracking of respiratory-induced tumor motion by dose-rate regulation

NASA Astrophysics Data System (ADS)

Han-Oh, Yeonju Sarah

We have developed a novel real-time tumor-tracking technology, called Dose-Rate-Regulated Tracking (DRRT), to compensate for tumor motion caused by breathing. Unlike other previously proposed tumor-tracking methods, this new method uses a preprogrammed dynamic multileaf collimator (MLC) sequence in combination with real-time dose-rate control. This new scheme circumvents the technical challenge in MLC-based tumor tracking, that is to control the MLC motion in real time, based on real-time detected tumor motion. The preprogrammed MLC sequence describes the movement of the tumor, as a function of breathing phase, amplitude, or tidal volume. The irregularity of tumor motion during treatment is handled by real-time regulation of the dose rate, which effectively speeds up or slows down the delivery of radiation as needed. This method is based on the fact that all of the parameters in dynamic radiation delivery, including MLC motion, are enslaved to the cumulative dose, which, in turn, can be accelerated or decelerated by varying the dose rate. Because commercially available MLC systems do not allow the MLC delivery sequence to be modified in real time based on the patient's breathing signal, previously proposed tumor-tracking techniques using a MLC cannot be readily implemented in the clinic today. By using a preprogrammed MLC sequence to handle the required motion, the task for real-time control is greatly simplified. We have developed and tested the pre- programmed MLC sequence and the dose-rate regulation algorithm using lung-cancer patients breathing signals. It has been shown that DRRT can track the tumor with an accuracy of less than 2 mm for a latency of the DRRT system of less than 0.35 s. We also have evaluated the usefulness of guided breathing for DRRT. Since DRRT by its very nature can compensate for breathing-period changes, guided breathing was shown to be unnecessary for real-time tracking when using DRRT. Finally, DRRT uses the existing dose-rate control system that is provided for current linear accelerators. Therefore, DRRT can be achieved with minimal modification of existing technology, and this can shorten substantially the time necessary to establish DRRT in clinical practice.

Feasibility study of volumetric modulated arc therapy with constant dose rate for endometrial cancer

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

Yang, Ruijie; Wang, Junjie, E-mail: junjiewang47@yahoo.com; Xu, Feng

2013-10-01

To investigate the feasibility, efficiency, and delivery accuracy of volumetric modulated arc therapy with constant dose rate (VMAT-CDR) for whole-pelvic radiotherapy (WPRT) of endometrial cancer. The nine-field intensity-modulated radiotherapy (IMRT), VMAT with variable dose-rate (VMAT-VDR), and VMAT-CDR plans were created for 9 patients with endometrial cancer undergoing WPRT. The dose distribution of planning target volume (PTV), organs at risk (OARs), and normal tissue (NT) were compared. The monitor units (MUs) and treatment delivery time were also evaluated. For each VMAT-CDR plan, a dry run was performed to assess the dosimetric accuracy with MatriXX from IBA. Compared with IMRT, the VMAT-CDRmore » plans delivered a slightly greater V{sub 20} of the bowel, bladder, pelvis bone, and NT, but significantly decreased the dose to the high-dose region of the rectum and pelvis bone. The MUs decreased from 1105 with IMRT to 628 with VMAT-CDR. The delivery time also decreased from 9.5 to 3.2 minutes. The average gamma pass rate was 95.6% at the 3%/3 mm criteria with MatriXX pretreatment verification for 9 patients. VMAT-CDR can achieve comparable plan quality with significant shorter delivery time and smaller number of MUs compared with IMRT for patients with endometrial cancer undergoing WPRT. It can be accurately delivered and be an alternative to IMRT on the linear accelerator without VDR capability.« less

Safety and immunogenicity of different doses and schedules of a live attenuated tetravalent dengue vaccine (TDV) in healthy adults: A Phase 1b randomized study.

PubMed

Rupp, Richard; Luckasen, Gary Joseph; Kirstein, Judith Lee; Osorio, Jorge E; Santangelo, Joseph D; Raanan, Marsha; Smith, Mary Kathryn; Wallace, Derek; Gordon, Gilad S; Stinchcomb, Dan T

2015-11-17

A safe, effective dengue vaccine that can simultaneously induce immunity to all four dengue virus serotypes (DENV-1-4) is a public health priority. A chimeric tetravalent dengue vaccine (TDV) based on an attenuated DENV-2 serotype backbone was evaluated in healthy, flavivirus-seronegative adults. In this randomized, multicenter, Phase 1b study conducted in the United States, the safety and immunogenicity of TDV were evaluated in 140 participants aged 18-45 years in six dosing regimen study groups. Participants were injected subcutaneously on Days 0 and 90; placebo (saline) was injected where appropriate to maintain double blinding. Three different TDV dosages (TDV, a vaccine in which TDV-4 had been increased three-fold, and a one-tenth TDV dose), and single or double dosing were evaluated in one and/or both arms. Primary endpoints were solicited and unsolicited adverse events (AEs) and seroconversion rates to DENV-1-4 at Day 120. The severity of all AEs was generally mild. The most common unsolicited AEs were headache (52%), fatigue (43%) and myalgia (29%). The incidence of injection site pain ranged from 29 to 64% and 5 to 52% among study groups after the first and second doses, respectively. At Day 120, the ranges of seroconversion rates among the groups were DEN-1: 84-100%; DEN-2: 96-100%; DEN-3: 83-100%; and DEN-4: 33-77%. More than 80% of participants in each group seroconverted to at least three dengue serotypes. Substantial GMT increases from baseline were observed for DEN-1-3 at all time points from Day 30 onward; DEN-4 GMT increases were lower. Increasing TDV-4 slightly increased DEN-4 GMT, did not impact DEN-2 and DEN-3 GMT, but reduced DEN-1 GMT. Neither multiple dosing in both arms, nor one-tenth TDV dosing meaningfully impacted GMT increases relative to TDV. All TDV doses and dosing schedules were well tolerated and immunogenic in healthy flavivirus-naive adults (ClinicalTrials.gov NCT01511250). Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

Dose-rate effects on the radiation-induced oxidation of electric cable used in nuclear power plants

NASA Astrophysics Data System (ADS)

Reynolds, A. B.; Bell, R. M.; Bryson, N. M. N.; Doyle, T. E.; Hall, M. B.; Mason, L. R.; Quintric, L.; Terwilliger, P. L.

1995-01-01

Dose-rate effects were measured for typical ethylene propylene rubber (EPR) and crosslinked polyethylene (XLPE) electric cable used in nuclear power plants. The radiation source was the 60Co Irradiation Facility at the University of Virginia. Dose rates were varied from 5 Gy/h to 2500 Gy/h. It was found that there is little or no dose-rate effect at low doses for four of the five EPR cable products tested from 2500 Gy/h down to dose rates of 5 Gy/h but perhaps a small dose-rate effect at high doses for dose rates above 340 Gy/h. A small dose-rate exists for the fifth EPR above 340 Gy/h at all doses. A dose-rate effect exists above 40 Gy/h for two of the three XLPE cable products tested, but there is no dose-rate for these XLPE's between 40 Gy/h and 5 Gy/h. These results indicate that the dose-rate effects observed are due to oxygen diffusion effects during heterogeneous aging and suggest that there is no dose-rate effect for either EPR or XLPE during homogeneous aging.

SU-F-T-619: Dose Evaluation of Specific Patient Plans Based On Monte Carlo Algorithm for a CyberKnife Stereotactic Radiosurgery System

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

Piao, J; PLA 302 Hospital, Beijing; Xu, S

2016-06-15

Purpose: This study will use Monte Carlo to simulate the Cyberknife system, and intend to develop the third-party tool to evaluate the dose verification of specific patient plans in TPS. Methods: By simulating the treatment head using the BEAMnrc and DOSXYZnrc software, the comparison between the calculated and measured data will be done to determine the beam parameters. The dose distribution calculated in the Raytracing, Monte Carlo algorithms of TPS (Multiplan Ver4.0.2) and in-house Monte Carlo simulation method for 30 patient plans, which included 10 head, lung and liver cases in each, were analyzed. The γ analysis with the combinedmore » 3mm/3% criteria would be introduced to quantitatively evaluate the difference of the accuracy between three algorithms. Results: More than 90% of the global error points were less than 2% for the comparison of the PDD and OAR curves after determining the mean energy and FWHM.The relative ideal Monte Carlo beam model had been established. Based on the quantitative evaluation of dose accuracy for three algorithms, the results of γ analysis shows that the passing rates (84.88±9.67% for head,98.83±1.05% for liver,98.26±1.87% for lung) of PTV in 30 plans between Monte Carlo simulation and TPS Monte Carlo algorithms were good. And the passing rates (95.93±3.12%,99.84±0.33% in each) of PTV in head and liver plans between Monte Carlo simulation and TPS Ray-tracing algorithms were also good. But the difference of DVHs in lung plans between Monte Carlo simulation and Ray-tracing algorithms was obvious, and the passing rate (51.263±38.964%) of γ criteria was not good. It is feasible that Monte Carlo simulation was used for verifying the dose distribution of patient plans. Conclusion: Monte Carlo simulation algorithm developed in the CyberKnife system of this study can be used as a reference tool for the third-party tool, which plays an important role in dose verification of patient plans. This work was supported in part by the grant from Chinese Natural Science Foundation (Grant No. 11275105). Thanks for the support from Accuray Corp.« less

SU-E-T-268: Differences in Treatment Plan Quality and Delivery Between Two Commercial Treatment Planning Systems for Volumetric Arc-Based Radiation Therapy

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

Chen, S; Zhang, H; Zhang, B

2015-06-15

Purpose: To clinically evaluate the differences in volumetric modulated arc therapy (VMAT) treatment plan and delivery between two commercial treatment planning systems. Methods: Two commercial VMAT treatment planning systems with different VMAT optimization algorithms and delivery approaches were evaluated. This study included 16 clinical VMAT plans performed with the first system: 2 spine, 4 head and neck (HN), 2 brain, 4 pancreas, and 4 pelvis plans. These 16 plans were then re-optimized with the same number of arcs using the second treatment planning system. Planning goals were invariant between the two systems. Gantry speed, dose rate modulation, MLC modulation, planmore » quality, number of monitor units (MUs), VMAT quality assurance (QA) results, and treatment delivery time were compared between the 2 systems. VMAT QA results were performed using Mapcheck2 and analyzed with gamma analysis (3mm/3% and 2mm/2%). Results: Similar plan quality was achieved with each VMAT optimization algorithm, and the difference in delivery time was minimal. Algorithm 1 achieved planning goals by highly modulating the MLC (total distance traveled by leaves (TL) = 193 cm average over control points per plan), while maintaining a relatively constant dose rate (dose-rate change <100 MU/min). Algorithm 2 involved less MLC modulation (TL = 143 cm per plan), but greater dose-rate modulation (range = 0-600 MU/min). The average number of MUs was 20% less for algorithm 2 (ratio of MUs for algorithms 2 and 1 ranged from 0.5-1). VMAT QA results were similar for all disease sites except HN plans. For HN plans, the average gamma passing rates were 88.5% (2mm/2%) and 96.9% (3mm/3%) for algorithm 1 and 97.9% (2mm/2%) and 99.6% (3mm/3%) for algorithm 2. Conclusion: Both VMAT optimization algorithms achieved comparable plan quality; however, fewer MUs were needed and QA results were more robust for Algorithm 2, which more highly modulated dose rate.« less

WE-EF-BRA-06: Feasibility of Spatially Modulated Proton Beams for Small Animal Research

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

Lee, E; Meyer, J

Purpose: To investigate the feasibility of proton minibeam radiotherapy (pMBRT) for small animal research. The motivation is to explore with protons the extraordinary normal tissue sparing effects to spatially modulated beams as observed on high flux synchrotron beam lines. We hypothesized that we can design a multi-slit collimator for our proton beam line to produce planar-parallel dose profiles with high modulation in the entrance region and homogenous dose coverage in the overlap of the Bragg peaks. Methods: The high dose rate 50 MeV research proton beamline at the University of Washington was modeled using the TOol for PArticle Simulation (TOPAS)more » Monte Carlo package. A brass collimator was implemented to generate proton minibeams. The collimator consists of an array of 2 cm long slits to cover an area of 2×2 cm{sup 2}. The slit widths (0.1–1 mm), center-to-center (ctc) distances (1–3 mm) and collimator thickness (1–7 cm) were varied to evaluate the effect on dose rate, the peak-to-valley dose ratios (PVDR) and the change of penumbra and peak width (FWHM) with depth. Results: The Bragg peak was at a depth of ∼21 mm. The penumbra and FWHM remained relatively constant to a depth of about 10–15 mm. The PVDR ranged from 1.6 to 26 and the dose rate dropped exponentially with collimator thickness. A uniform dose can be achieved at depth with slightly compromised PVDRs and dose rate. Conclusion: The technical realization of pMBRT is feasible. The simulations have shown that it is possible to obtain uniform dose at depth while modulation is maintained on the entrance side. While the simulated beam widths are larger than on synchrotron generated microbeams the dosimetric advantage could avoid having to interlace two microbeams to achieve uniform dose in the target. The next steps are to build a collimator and verify the simulations experimentally.« less

Dosimetric and radiobiological comparison of volumetric modulated arc therapy, high-dose rate brachytherapy, and low-dose rate permanent seeds implant for localized prostate cancer.

PubMed

Yang, Ruijie; Zhao, Nan; Liao, Anyan; Wang, Hao; Qu, Ang

2016-01-01

To investigate the dosimetric and radiobiological differences among volumetric modulated arc therapy (VMAT), high-dose rate (HDR) brachytherapy, and low-dose rate (LDR) permanent seeds implant for localized prostate cancer. A total of 10 patients with localized prostate cancer were selected for this study. VMAT, HDR brachytherapy, and LDR permanent seeds implant plans were created for each patient. For VMAT, planning target volume (PTV) was defined as the clinical target volume plus a margin of 5mm. Rectum, bladder, urethra, and femoral heads were considered as organs at risk. A 78Gy in 39 fractions were prescribed for PTV. For HDR and LDR plans, the dose prescription was D90 of 34Gy in 8.5Gy per fraction, and 145Gy to clinical target volume, respectively. The dose and dose volume parameters were evaluated for target, organs at risk, and normal tissue. Physical dose was converted to dose based on 2-Gy fractions (equivalent dose in 2Gy per fraction, EQD2) for comparison of 3 techniques. HDR and LDR significantly reduced the dose to rectum and bladder compared with VMAT. The Dmean (EQD2) of rectum decreased 22.36Gy in HDR and 17.01Gy in LDR from 30.24Gy in VMAT, respectively. The Dmean (EQD2) of bladder decreased 6.91Gy in HDR and 2.53Gy in LDR from 13.46Gy in VMAT. For the femoral heads and normal tissue, the mean doses were also significantly reduced in both HDR and LDR compared with VMAT. For the urethra, the mean dose (EQD2) was 80.26, 70.23, and 104.91Gy in VMAT, HDR, and LDR brachytherapy, respectively. For localized prostate cancer, both HDR and LDR brachytherapy were clearly superior in the sparing of rectum, bladder, femoral heads, and normal tissue compared with VMAT. HDR provided the advantage in sparing of urethra compared with VMAT and LDR. Copyright © 2016 American Association of Medical Dosimetrists. Published by Elsevier Inc. All rights reserved.

Dosimetric and radiobiological comparison of volumetric modulated arc therapy, high-dose rate brachytherapy, and low-dose rate permanent seeds implant for localized prostate cancer

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

Yang, Ruijie, E-mail: ruijyang@yahoo.com; Zhao, Nan; Liao, Anyan

To investigate the dosimetric and radiobiological differences among volumetric modulated arc therapy (VMAT), high-dose rate (HDR) brachytherapy, and low-dose rate (LDR) permanent seeds implant for localized prostate cancer. A total of 10 patients with localized prostate cancer were selected for this study. VMAT, HDR brachytherapy, and LDR permanent seeds implant plans were created for each patient. For VMAT, planning target volume (PTV) was defined as the clinical target volume plus a margin of 5 mm. Rectum, bladder, urethra, and femoral heads were considered as organs at risk. A 78 Gy in 39 fractions were prescribed for PTV. For HDR andmore » LDR plans, the dose prescription was D{sub 90} of 34 Gy in 8.5 Gy per fraction, and 145 Gy to clinical target volume, respectively. The dose and dose volume parameters were evaluated for target, organs at risk, and normal tissue. Physical dose was converted to dose based on 2-Gy fractions (equivalent dose in 2 Gy per fraction, EQD{sub 2}) for comparison of 3 techniques. HDR and LDR significantly reduced the dose to rectum and bladder compared with VMAT. The D{sub mean} (EQD{sub 2}) of rectum decreased 22.36 Gy in HDR and 17.01 Gy in LDR from 30.24 Gy in VMAT, respectively. The D{sub mean} (EQD{sub 2}) of bladder decreased 6.91 Gy in HDR and 2.53 Gy in LDR from 13.46 Gy in VMAT. For the femoral heads and normal tissue, the mean doses were also significantly reduced in both HDR and LDR compared with VMAT. For the urethra, the mean dose (EQD{sub 2}) was 80.26, 70.23, and 104.91 Gy in VMAT, HDR, and LDR brachytherapy, respectively. For localized prostate cancer, both HDR and LDR brachytherapy were clearly superior in the sparing of rectum, bladder, femoral heads, and normal tissue compared with VMAT. HDR provided the advantage in sparing of urethra compared with VMAT and LDR.« less

Single-Dose Oritavancin Treatment of Acute Bacterial Skin and Skin Structure Infections: SOLO Trial Efficacy by Eron Severity and Management Setting.

PubMed

Deck, Daniel H; Jordan, Jennifer M; Holland, Thomas L; Fan, Weihong; Wikler, Matthew A; Sulham, Katherine A; Ralph Corey, G

2016-09-01

Introduction of new antibiotics enabling single-dose administration, such as oritavancin may significantly impact site of care decisions for patients with acute bacterial skin and skin structure infections (ABSSSI). This analysis compared the efficacy of single-dose oritavancin with multiple-dose vancomycin in patients categorized according to disease severity via modified Eron classification and management setting. SOLO I and II were phase 3 studies evaluating single-dose oritavancin versus 7-10 days of vancomycin for treatment of ABSSSI. Patient characteristics were collected at baseline and retrospectively analyzed. Study protocols were amended, allowing outpatient management at the discretion of investigators. In this post hoc analysis, patients were categorized according to a modified Eron severity classification and management setting (outpatient vs. inpatient) and the efficacy compared. Overall, 1910 patients in the SOLO trials were categorized into Class I (520, 26.5%), II (790, 40.3%), and III (600, 30.6%). Of the 767 patients (40%) in the SOLO trials who were managed entirely in the outpatient setting 40.3% were categorized as Class II and 30.6% were Class III. Clinical efficacy was similar between oritavancin and vancomycin treatment groups, regardless of severity classification and across inpatient and outpatient settings. Class III patients had lower response rates (oritavancin 73.3%, vancomycin 76.6%) at early clinical evaluation when compared to patients in Class I (82.6%) or II (86.1%); however, clinical cure rates at the post-therapy evaluation were similar for Class III patients (oritavancin 79.8%, vancomycin 79.9%) when compared to Class I and II patients (79.1-85.7%). Single-dose oritavancin therapy results in efficacy comparable to multiple-dose vancomycin in patients categorized according to modified Eron disease severity classification regardless of whether management occurred in the inpatient or outpatient setting. The Medicines Company, Parsippany, NJ, USA. ClinicalTrials.gov identifiers, NCT01252719 (SOLO I) and NCT01252732 (SOLO II).

A retrospective analysis for patient-specific quality assurance of volumetric-modulated arc therapy plans.

PubMed

Li, Guangjun; Wu, Kui; Peng, Guang; Zhang, Yingjie; Bai, Sen

2014-01-01

Volumetric-modulated arc therapy (VMAT) is now widely used clinically, as it is capable of delivering a highly conformal dose distribution in a short time interval. We retrospectively analyzed patient-specific quality assurance (QA) of VMAT and examined the relationships between the planning parameters and the QA results. A total of 118 clinical VMAT cases underwent pretreatment QA. All plans had 3-dimensional diode array measurements, and 69 also had ion chamber measurements. Dose distribution and isocenter point dose were evaluated by comparing the measurements and the treatment planning system (TPS) calculations. In addition, the relationship between QA results and several planning parameters, such as dose level, control points (CPs), monitor units (MUs), average field width, and average leaf travel, were also analyzed. For delivered dose distribution, a gamma analysis passing rate greater than 90% was obtained for all plans and greater than 95% for 100 of 118 plans with the 3%/3-mm criteria. The difference (mean ± standard deviation) between the point doses measured by the ion chamber and those calculated by TPS was 0.9% ± 2.0% for all plans. For all cancer sites, nasopharyngeal carcinoma and gastric cancer have the lowest and highest average passing rates, respectively. From multivariate linear regression analysis, the dose level (p = 0.001) and the average leaf travel (p < 0.001) showed negative correlations with the passing rate, and the average field width (p = 0.003) showed a positive correlation with the passing rate, all indicating a correlation between the passing rate and the plan complexity. No statistically significant correlation was found between MU or CP and the passing rate. Analysis of the results of dosimetric pretreatment measurements as a function of VMAT plan parameters can provide important information to guide the plan parameter setting and optimization in TPS. Copyright © 2014 American Association of Medical Dosimetrists. Published by Elsevier Inc. All rights reserved.

WE-DE-201-05: Evaluation of a Windowless Extrapolation Chamber Design and Monte Carlo Based Corrections for the Calibration of Ophthalmic Applicators

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

Hansen, J; Culberson, W; DeWerd, L

Purpose: To test the validity of a windowless extrapolation chamber used to measure surface dose rate from planar ophthalmic applicators and to compare different Monte Carlo based codes for deriving correction factors. Methods: Dose rate measurements were performed using a windowless, planar extrapolation chamber with a {sup 90}Sr/{sup 90}Y Tracerlab RA-1 ophthalmic applicator previously calibrated at the National Institute of Standards and Technology (NIST). Capacitance measurements were performed to estimate the initial air gap width between the source face and collecting electrode. Current was measured as a function of air gap, and Bragg-Gray cavity theory was used to calculate themore » absorbed dose rate to water. To determine correction factors for backscatter, divergence, and attenuation from the Mylar entrance window found in the NIST extrapolation chamber, both EGSnrc Monte Carlo user code and Monte Carlo N-Particle Transport Code (MCNP) were utilized. Simulation results were compared with experimental current readings from the windowless extrapolation chamber as a function of air gap. Additionally, measured dose rate values were compared with the expected result from the NIST source calibration to test the validity of the windowless chamber design. Results: Better agreement was seen between EGSnrc simulated dose results and experimental current readings at very small air gaps (<100 µm) for the windowless extrapolation chamber, while MCNP results demonstrated divergence at these small gap widths. Three separate dose rate measurements were performed with the RA-1 applicator. The average observed difference from the expected result based on the NIST calibration was −1.88% with a statistical standard deviation of 0.39% (k=1). Conclusion: EGSnrc user code will be used during future work to derive correction factors for extrapolation chamber measurements. Additionally, experiment results suggest that an entrance window is not needed in order for an extrapolation chamber to provide accurate dose rate measurements for a planar ophthalmic applicator.« less

A retrospective analysis for patient-specific quality assurance of volumetric-modulated arc therapy plans

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

Li, Guangjun; Wu, Kui; Peng, Guang

2014-01-01

Volumetric-modulated arc therapy (VMAT) is now widely used clinically, as it is capable of delivering a highly conformal dose distribution in a short time interval. We retrospectively analyzed patient-specific quality assurance (QA) of VMAT and examined the relationships between the planning parameters and the QA results. A total of 118 clinical VMAT cases underwent pretreatment QA. All plans had 3-dimensional diode array measurements, and 69 also had ion chamber measurements. Dose distribution and isocenter point dose were evaluated by comparing the measurements and the treatment planning system (TPS) calculations. In addition, the relationship between QA results and several planning parameters,more » such as dose level, control points (CPs), monitor units (MUs), average field width, and average leaf travel, were also analyzed. For delivered dose distribution, a gamma analysis passing rate greater than 90% was obtained for all plans and greater than 95% for 100 of 118 plans with the 3%/3-mm criteria. The difference (mean ± standard deviation) between the point doses measured by the ion chamber and those calculated by TPS was 0.9% ± 2.0% for all plans. For all cancer sites, nasopharyngeal carcinoma and gastric cancer have the lowest and highest average passing rates, respectively. From multivariate linear regression analysis, the dose level (p = 0.001) and the average leaf travel (p < 0.001) showed negative correlations with the passing rate, and the average field width (p = 0.003) showed a positive correlation with the passing rate, all indicating a correlation between the passing rate and the plan complexity. No statistically significant correlation was found between MU or CP and the passing rate. Analysis of the results of dosimetric pretreatment measurements as a function of VMAT plan parameters can provide important information to guide the plan parameter setting and optimization in TPS.« less

SU-E-T-579: Impact of Cylinder Size in High-Dose Rate Brachytherapy (HDRBT) for Primary Cancer in the Vagina

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

Zhang, H; Gopalakrishnan, M; Lee, P

2014-06-01

Purpose: To evaluate the dosimetric impact of cylinder size in high dose rate Brachytherapy for primary vaginal cancers. Methods: Patients treated with HDR vaginal vault radiation in a list of cylinders ranging from 2.5 to 4 cm in diameter at 0.5 cm increment were analyzed. All patients’ doses were prescribed at the 0.5 cm from the vaginal surface with different treatment lengths. A series of reference points were created to optimize the dose distribution. The fraction dose was 5.5 Gy, the treatment was repeated for 4 times in two weeks. A cylinder volume was contoured in each case according tomore » the prescribed treatment length, and then expanded to 5 mm to get a volume Cylinder-5mm-exp. A volume of PTV-Eval was obtained by subtracting the cylinder volume from the Cylinder-5mm-exp. The shell volume, PTV-Eval serves as the target volume for dosimetric evaluation. Results: DVH curves and average doses of PTV-Eval were obtained. Our results indicated that the DVH curves shifted toward higher dose side when larger cylinder was used instead of smaller ones. When 3.0 cm cylinder was used instead of 2.5 cm, for 3.0 cm treatment length, the average dose only increased 1%, from 790 to 799 cGy. However, the average doses for 3.5 and 4 cm cylinders respectively are 932 and 1137 cGy at the same treatment length. For 5.0 cm treatment length, the average dose is 741 cGy for 2.5 cm cylinder, and 859 cGy for 3 cm cylinder. Conclusion: Our data analysis suggests that for the vaginal intracavitary HDRBT, the average dose is at least 35% larger than the prescribed dose in the studied cases; the size of the cylinder will impact the dose delivered to the target volume. The cylinder with bigger diameter tends to deliver larger average dose to the PTV-Eval.« less

Typical doses and dose rates in studies pertinent to radiation risk inference at low doses and low dose rates

PubMed Central

Rühm, Werner; Azizova, Tamara; Bouffler, Simon; Cullings, Harry M; Grosche, Bernd; Little, Mark P; Shore, Roy S; Walsh, Linda; Woloschak, Gayle E

2018-01-01

Abstract In order to quantify radiation risks at exposure scenarios relevant for radiation protection, often extrapolation of data obtained at high doses and high dose rates down to low doses and low dose rates is needed. Task Group TG91 on ‘Radiation Risk Inference at Low-dose and Low-dose Rate Exposure for Radiological Protection Purposes’ of the International Commission on Radiological Protection is currently reviewing the relevant cellular, animal and human studies that could be used for that purpose. This paper provides an overview of dose rates and doses typically used or present in those studies, and compares them with doses and dose rates typical of those received by the A-bomb survivors in Japan. PMID:29432579

The efficacy of intracoelomic fospropofol in red-eared sliders (Trachemys scripta elegans).

PubMed

Schroeder, Carrie A; Johnson, Rebecca A

2013-12-01

Intravenous anesthetic delivery in reptiles can be challenging. Current injectable techniques have varied induction/recovery times and anesthetic quality. This study hypothesized that intracoelomic administration of a new anesthetic, fospropofol, in turtles would result in dose-dependent anesthesia and respiratory depression. A two-part prospective trial using adult red-eared slider turtles (Trachemys scripta elegans) weighing 764 +/- 17 g was conducted to determine an effective anesthetic dose and to evaluate the anesthetic quality, duration, and respiratory effects of an efficacious dose. In part 1, six turtles were randomly administered 25-mg/ kg (low-dose [LD]) and 50-mg/kg (high-dose [HD]) fospropofol in a crossover design. Respiratory rate, immobility, and muscle relaxation scores were evaluated for 180 min. In part 2, eight turtles were administered HD fospropofol. Immobility and muscle relaxation (front and hind limb) scores and time to endotracheal intubation/extubation were evaluated until scores returned to baseline. In part 1, the LD group had significantly lower immobility and muscle relaxation scores versus the HD group over time (both P < 0.05); scores were significantly elevated from baseline for 20-120 min and 15-180 min, respectively (all P < 0.05). Although not significantly different between groups (P > 0.05), respiratory rate was significantly decreased from baseline from 10 to 120 min (all P < 0.05). In part 2, HD fospropofol decreased respiratory rate from 21.5 +/- 2.9 breaths/min to 0.1 +/- 0.1 breaths/min, similar to the results in part 1. Maximal reductions in mobility and front and hind limb motor tone occurred at 39.0 +/- 4.1, 30.8 +/- 3.6, and 24.0 +/- 3.6 min, respectively. Intubation in 7/8 turtles occurred at 45.7 +/- 5.4 min and extubation at 147.0 +/- 23.2 min. However, 2/8 turtles showed prolonged anesthetic effects, requiring resuscitative efforts for recovery. Due to the unpredictable quality and duration of anesthesia with intracoelomic fospropofol, it should be used with caution for general anesthesia in red-eared sliders at the doses and administration route investigated.

THE EFFICACY OF INTRACOELOMIC FOSPROPOFOL IN RED-EARED SLIDERS (TRACHEMYS SCRIPTA)

PubMed Central

Schroeder, Carrie A.; Johnson, Rebecca A.

2015-01-01

Intravenous anesthetic delivery in reptiles can be challenging; current injectable techniques have varied induction/recovery times and anesthetic quality. This study hypothesized that intracoelomic administration of a new anesthetic, fospropofol, in turtles would result in dose-dependent anesthesia and respiratory depression. A two-part prospective trial using adult red-eared slider turtles (Trachemys scripta) weighing 764±17 g was conducted to 1) determine an effective anesthetic dose, and 2) evaluate the anesthetic quality, duration and respiratory effects of an efficacious dose. In Part 1, six turtles were randomly administered 25 mg kg−1 (low dose: LD) and 50 mg kg−1 (high dose: HD) fospropofol in a cross-over design. Respiratory rate, immobility and muscle relaxation scores were evaluated for 180 minutes. In Part 2, eight turtles were administered HD fospropofol. Immobility and muscle relaxation (front and hind limb) scores, and time to endotracheal intubation/extubation were evaluated until scores returned to baseline. In Part 1, the LD group had significantly lower immobility and muscle relaxation scores versus the HD group over time (both P<0.05); scores were significantly elevated from baseline for 20–120 minutes and 15–180 minutes, respectively (all P<0.05). Although not significantly different between groups (P>0.05), respiratory rate was significantly decreased from baseline from 10–120 minutes (all P<0.05). In Part 2, HD fospropofol decreased respiratory rate from 21.5±2.9 breaths min−1 to 0.1±0.1 breaths min−1, similar to the results in Part 1. Maximal reductions in immobility, front and hind limb motor tone occurred at 39.0±4.1, 30.8±3.6, and 24.0±3.6 minutes, respectively. Intubation in 7/8 turtles occurred at 45.7±5.4 min and extubation at 147.0±23.2 min. However, 2/8 turtles showed prolonged anesthetic effects, requiring resuscitative efforts for recovery. Due to the unpredictable quality and duration of anesthesia with intracoelomic fospropofol, it should be used with caution for general anesthesia in red-eared sliders at the doses and administration route investigated. PMID:24450053

Effects of an injectable trace mineral supplement on first-service conception rate of dairy cows.

PubMed

Vanegas, J A; Reynolds, J; Atwill, E R

2004-11-01

A total of 825 dairy cows from a commercial dairy farm in central California were used to evaluate effects of one or 2 doses of an injectable trace mineral supplement containing 20 mg/mL of zinc, 20 mg/mL of manganese, 5 mg/mL of selenium, and 10 mg/mL of copper on first-service conception rate. Cows were randomly allocated into treatment or control group to either a single dose (experiment 1) or a double dose (experiment 2) of injected supplement. Allocation was based on days in lactation for experiment 1 and the length of gestation periods for experiment 2. In experiment 1, cows 38 to 45 d in lactation (n = 190) received a single dose of 5 mL of injected supplement. Similar cows were used as controls (n = 227). In experiment 2, cows and pregnant heifers received an initial injection of 5 mL of the mineral supplement from 2 to 3 wk precalving (n = 186). An equal dose was repeated 38 to 45 d in lactation. A similar group of cows and pregnant heifers served as controls for experiment 2 (n = 222). Health and reproductive events postcalving were recorded. In experiment 1, the odds of first-service conception were not significantly different for cows receiving a one-dose regimen of minerals compared with untreated control cows; conception rates were 26.8 and 27.5% for experiment 1 treatment and control groups, respectively. In experiment 1, the odds of first-service conception were significantly lower (odds ratio = 0.66) for cows and heifers given the 2-dose regimen of minerals compared with untreated controls; overall conception rates were 21.5 and 31.5% for experiment 2 treatment and control groups, respectively. In this intensively managed dairy herd, a single dose of injected trace minerals before breeding had no beneficial effects on first-service conception rate. However, dairy cows receiving a dose of trace minerals before calving and another dose before breeding had lower conception at first service.

Is high–dose rate RapidArc-based radiosurgery dosimetrically advantageous for the treatment of intracranial tumors?

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

Zhao, Bo; Yang, Yong, E-mail: yangy2@upmc.edu; Li, Xiang

In linac-based stereotactic radiosurgery (SRS) and radiotherapy (SRT), circular cone(s) or conformal arc(s) are conventionally used to treat intracranial lesions. However, when the target is in close proximity to critical structures, it is frequently quite challenging to generate a quality plan using these techniques. In this study, we investigated the dosimetric characteristics of using high–dose rate RapidArc (RA) technique for radiosurgical treatment of intracranial lesions. A total of 10 intracranial SRS/SRT cases previously planned using dynamic conformal arc (DCA) or cone-based techniques have been included in this study. For each case, 3 treatment plans were generated: (1) a DCA planmore » with multiple noncoplanar arcs, (2) a high–dose rate RA plan with arcs oriented the same as DCA (multiple-arc RA), and 3) a high–dose rate RA plan with a single coplanar arc (single-arc RA). All treatment plans were generated under the same prescription and similar critical structure dose limits. Plan quality for different plans was evaluated by comparing various dosimetric parameters such as target coverage, conformity index (CI), homogeneity index (HI), critical structures, and normal brain tissue doses as well as beam delivery time. With similar critical structure sparing, high–dose rate RA plans can achieve much better target coverage, dose conformity, and dose homogeneity than the DCA plans can. Plan quality indices CI and HI, for the DCA, multiple-arc RA, and single-arc RA techniques, were measured as 1.67 ± 0.39, 1.32 ± 0.28, and 1.38 ± 0.30 and 1.24 ± 0.11, 1.10 ± 0.04, and 1.12 ± 0.07, respectively. Normal brain tissue dose (V{sub 12} {sub Gy}) was found to be similar for DCA and multiple-arc RA plans but much larger for the single-arc RA plans. Beam delivery was similar for DCA and multiple-arc RA plans but shorter with single-arc RA plans. Multiple-arc RA SRS/SRT can provide better treatment plans than conventional DCA plans, especially for complex cases.« less

Important Physiological Parameters and Physical Activity Data for Evaluating Exposure Modeling Performance: a Synthesis

EPA Science Inventory

The purpose of this report is to develop a database of physiological parameters needed for understanding and evaluating performance of the APEX and SHEDS exposure/intake dose rate model used by the Environmental Protection Agency (EPA) as part of its regulatory activities. The A...

Tolerance to effects of high-dose oral δ9-tetrahydrocannabinol and plasma cannabinoid concentrations in male daily cannabis smokers.

PubMed

Gorelick, David A; Goodwin, Robert S; Schwilke, Eugene; Schwope, David M; Darwin, William D; Kelly, Deanna L; McMahon, Robert P; Liu, Fang; Ortemann-Renon, Catherine; Bonnet, Denis; Huestis, Marilyn A

2013-01-01

Oral cannabinoids are taken for medicinal or recreational purposes, yet little is known about tolerance to their effects after high-dose extended exposure. The development of tolerance to effects of around-the-clock oral synthetic Δ9-tetrahydrocannabinol (THC) (20 mg every 3.5-6 h) was evaluated in 13 healthy male daily cannabis smokers residing on a secure research unit: 40 mg on Day 1; 100 mg on Days 2-4; 120 mg on Days 5-6. Systolic and diastolic blood pressure (BP), heart rate, and symptoms of subjective intoxication (100 mm visual-analogue scales, VAS) were assessed the morning of Day 1 (before any oral THC), and on Days 2, 4 and 6, every 30 min for 3 h after the first morning THC dose. Morning subjective intoxication ratings increased from Days 1 to 2, and then declined on Days 4 and 6. The morning THC dose increased intoxication ratings on Day 2, but had less effect on Days 4 and 6, a pattern consistent with tolerance. THC lowered BP and increased heart rate over the six days. Plasma THC and 11-OH-THC concentrations increased significantly over the first five days of dosing. Six days of around-the-clock, oral THC produced tolerance to subjective intoxication, but not to cardiovascular effects.

Dose reduction of up to 89% while maintaining image quality in cardiovascular CT achieved with prospective ECG gating

NASA Astrophysics Data System (ADS)

Londt, John H.; Shreter, Uri; Vass, Melissa; Hsieh, Jiang; Ge, Zhanyu; Adda, Olivier; Dowe, David A.; Sabllayrolles, Jean-Louis

2007-03-01

We present the results of dose and image quality performance evaluation of a novel, prospective ECG-gated Coronary CT Angiography acquisition mode (SnapShot Pulse, LightSpeed VCT-XT scanner, GE Healthcare, Waukesha, WI), and compare it to conventional retrospective ECG gated helical acquisition in clinical and phantom studies. Image quality phantoms were used to measure noise, slice sensitivity profile, in-plane resolution, low contrast detectability and dose, using the two acquisition modes. Clinical image quality and diagnostic confidence were evaluated in a study of 31 patients scanned with the two acquisition modes. Radiation dose reduction in clinical practice was evaluated by tracking 120 consecutive patients scanned with the prospectively gated scan mode. In the phantom measurements, the prospectively gated mode resulted in equivalent or better image quality measures at dose reductions of up to 89% compared to non-ECG modulated conventional helical scans. In the clinical study, image quality was rated excellent by expert radiologist reviewing the cases, with pathology being identical using the two acquisition modes. The average dose to patients in the clinical practice study was 5.6 mSv, representing 50% reduction compared to a similar patient population scanned with the conventional helical mode.

A Commentary on: "A History of the United States Department of Energy (DOE) Low Dose Radiation Research Program: 1998-2008".

PubMed

Brooks, Antone L

2015-04-01

This commentary provides a very brief overview of the book "A History of the United States Department of Energy (DOE) Low Dose Radiation Research Program: 1998-2008" ( http://lowdose.energy.gov ). The book summarizes and evaluates the research progress, publications and impact of the U.S. Department of Energy Low Dose Radiation Research Program over its first 10 years. The purpose of this book was to summarize the impact of the program's research on the current thinking and low-dose paradigms associated with the radiation biology field and to help stimulate research on the potential adverse and/or protective health effects of low doses of ionizing radiation. In addition, this book provides a summary of the data generated in the low dose program and a scientific background for anyone interested in conducting future research on the effects of low-dose or low-dose-rate radiation exposure. This book's exhaustive list of publications coupled with discussions of major observations should provide a significant resource for future research in the low-dose and dose-rate region. However, because of space limitations, only a limited number of critical references are mentioned. Finally, this history book provides a list of major advancements that were accomplished by the program in the field of radiation biology, and these bulleted highlights can be found in last part of chapters 4-10.

Dose rate mapping of VMAT treatments

NASA Astrophysics Data System (ADS)

Podesta, Mark; Antoniu Popescu, I.; Verhaegen, Frank

2016-06-01

Human tissues exhibit a varying response to radiation dose depending on the dose rate and fractionation scheme used. Dose rate effects have been reported for different radiations, and tissue types. The literature indicates that there is not a significant difference in response for low-LET radiation when using dose rates between 1 Gy min-1 and 12 Gy min-1 but lower dose rates have an observable sparing effect on tissues and a differential effect between tissues. In intensity-modulated radiotherapy such as volumetric modulated arc therapy (VMAT) the dose can be delivered with a wide range of dose rates. In this work we developed a method based on time-resolved Monte Carlo simulations to quantify the dose rate frequency distribution for clinical VMAT treatments for three cancer sites, head and neck, lung, and pelvis within both planning target volumes (PTV) and normal tissues. The results show a wide range of dose rates are used to deliver dose in VMAT and up to 75% of the PTV can have its dose delivered with dose rates  <1 Gy min-1. Pelvic plans on average have a lower mean dose rate within the PTV than lung or head and neck plans but a comparable mean dose rate within the organs at risk. Two VMAT plans that fulfil the same dose objectives and constraints may be delivered with different dose rate distributions, particularly when comparing single arcs to multiple arc plans. It is concluded that for dynamic plans, the dose rate range used varies to a larger degree than previously assumed. The effect of the dose rate range in VMAT on clinical outcome is unknown.

Evaluation of an intragastric challenge model for Shigella dysenteriae 1 in rhesus monkeys (Macaca mulatta) for the pre-clinical assessment of Shigella vaccine formulations

PubMed Central

Islam, Dilara; Ruamsap, Nattaya; Khantapura, Patchariya; Aksomboon, Ajchara; Srijan, Apichai; Wongstitwilairoong, Boonchai; Bodhidatta, Ladaporn; Gettayacamin, Montip; Venkatesan, Malabi M; Mason, Carl J

2014-01-01

Shigellosis is a worldwide disease, characterized by abdominal pain, fever, vomiting, and the passage of blood- and mucus-streaked stools. Rhesus monkeys and other primates are the only animals that are naturally susceptible to shigellosis. A suitable animal model is required for the pre-clinical evaluation of vaccines candidates. In this study, the minimal dose of Shigella dysenteriae1 1617 strain required to produce dysentery in four of five (80% attack rate) monkeys using an escalating dose range for three groups [2 × 108, 2 × 109 and 2 × 1010 colony forming unit (CFU)] was determined. In addition, the monkeys were re-infected. The identified optimal challenge dose was 2 × 109 CFU; this dose elicited 60% protection in monkeys when they were re-challenged with a one log higher dose (2 × 1010 CFU). The challenge dose, 2 × 1010 CFU, produced severe dysentery in all monkeys, with one monkey dying within 24 h, elicited 100% protection when re-challenged with the same dose. All monkeys exhibited immune responses. This study concludes that the rhesus monkey model closely mimics the disease and immune response seen in humans and is a suitable animal model for the pre-clinical evaluation of Shigella vaccine candidates. Prior infection with the 1617 strain can protect monkeys against subsequent re-challenges with homologous strains. PMID:24028276

Dosimetric evaluation of a MOSFET detector for clinical application in photon therapy.

PubMed

Kohno, Ryosuke; Hirano, Eriko; Nishio, Teiji; Miyagishi, Tomoko; Goka, Tomonori; Kawashima, Mitsuhiko; Ogino, Takashi

2008-01-01

Dosimetric characteristics of a metal oxide-silicon semiconductor field effect transistor (MOSFET) detector are studied with megavoltage photon beams for patient dose verification. The major advantages of this detector are its size, which makes it a point dosimeter, and its ease of use. In order to use the MOSFET detector for dose verification of intensity-modulated radiation therapy (IMRT) and in-vivo dosimetry for radiation therapy, we need to evaluate the dosimetric properties of the MOSFET detector. Therefore, we investigated the reproducibility, dose-rate effect, accumulated-dose effect, angular dependence, and accuracy in tissue-maximum ratio measurements. Then, as it takes about 20 min in actual IMRT for the patient, we evaluated fading effect of MOSFET response. When the MOSFETs were read-out 20 min after irradiation, we observed a fading effect of 0.9% with 0.9% standard error of the mean. Further, we applied the MOSFET to the measurement of small field total scatter factor. The MOSFET for dose measurements of small field sizes was better than the reference pinpoint chamber with vertical direction. In conclusion, we assessed the accuracy, reliability, and usefulness of the MOSFET detector in clinical applications such as pinpoint absolute dosimetry for small fields.

An evaluation of some pertinent parameters that influence the dosimetric performance of synthetic diamond detectors

NASA Astrophysics Data System (ADS)

Ade, N.; Nam, T. L.; Mhlanga, S. H.

2013-05-01

Although the near-tissue equivalence of diamond allows the direct measurement of dose for clinical applications without the need for energy-corrections, it is often cited that diamond detectors require pre-irradiation, a procedure necessary to stabilize the response or sensitivity of a diamond detector before dose measurements. In addition it has been pointed out that the relative dose measured with a diamond detector requires dose rate dependence correction and that the angular dependence of a detector could be due to its mechanical design or to the intrinsic angular sensitivity of the detection process. While the cause of instability of response has not been meticulously investigated, the issue of dose rate dependence correction is uncertain as some studies ignored it but reported good results. The aims of this study were therefore to investigate, in particular (1) the major cause of the unstable response of diamond detectors requiring pre-irradiation; (2) the influence of dose rate dependence correction in relative dose measurements; and (3) the angular dependence of the diamond detectors. The study was conducted with low-energy X-rays and electron therapy beams on HPHT and CVD synthesized diamonds. Ionization chambers were used for comparative measurements. Through systematic investigations, the major cause of the unstable response of diamond detectors requiring the recommended pre-irradiation step was isolated and attributed to the presence and effects of ambient light. The variation in detector's response between measurements in light and dark conditions could be as high as 63% for a CVD diamond. Dose rate dependence parameters (Δ values) of 0.950 and 1.035 were found for the HPHT and CVD diamond detectors, respectively. Without corrections based on dose rate dependence, the relative differences between depth-doses measured with the diamond detectors and a Markus chamber for exposures to 7 and 14 MeV electron beams were within 2.5%. A dose rate dependence correction using the Δ values obtained seemed to worsen the performance of the HPHT sample (up to about 3.3%) but it had a marginal effect on the performance of the CVD sample. In addition, the angular response of the CVD diamond detector was shown to be comparable with that of a cylindrical chamber. This study concludes that once the responses of the diamond detectors have been stabilised and they are properly shielded from ambient light, pre-irradiation prior to each measurement is not required. Also, the relative dose measured with the diamond detectors do not require dose rate dependence corrections as the required correction is only marginal and could have no dosimetric significance.

Effects of HMX exposure upon metabolic rate of northern bobwhite quail (Colinus virginianus) in ovo.

PubMed

Liu, Jun; Cox, Stephen B; Beall, Blake; Brunjes, Kristina J; Pan, Xiaoping; Kendall, Ronald J; Anderson, Todd A; McMurry, Scott T; Cobb, George P; Smith, Philip N

2008-05-01

We evaluated the use of the gas exchange rate as an ecologically relevant indicator of chemical stress in avian embryos/eggs. Northern bobwhite quail (Colinus virginianus) were exposed to octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) via feed containing nominal concentrations of 0, 12.5, 50.0, and 125.0 mg kg(-1). Metabolic rates (oxygen consumption) of developing quail eggs were then measured via respirometry to examine potential effects of HMX exposure. Metabolic rates were examined on 5, 9, and 21 d of incubation. Next, concentrations of HMX in embryos/eggs were determined by liquid chromatography-mass spectrometry. Mean (+/-SE) concentrations of HMX in eggs were 21.0+/-5.9, 1113+/-79.0, 3864+/-154.0, and 7426+/-301.1 ng g(-1) in control, low, medium and high dose groups, respectively. There were significant differences in oxygen consumption among the three embryo ages, however differences among the ages were not consistent among dose groups (age x dose group interaction p<0.0001). Oxygen consumption rates did not vary as a function of HMX in embryos (p=0.18). No evidence was observed for alterations of in ovo metabolic rates associated with HMX exposure.

Serum toxicokinetics after intravenous and oral dosing of larkspur toxins in goats.

PubMed

Welch, K D; Gardner, D R; Stonecipher, C A; Green, B T; Pfister, J A

2017-07-01

Poisoning of cattle by larkspur plants (Delphinium spp.) is a concern for cattle ranchers in western North America. Previous research studies have evaluated the toxicokinetic profile of multiple larkspur toxins in several livestock species. However, those studies were all performed by orally dosing plant material. Consequently some toxicokinetic parameters could not be definitively determined. In this study, we compared the serum toxicokinetic profile of the larkspur alkaloids methyllycaconitine (MLA) and deltaline in goats dosed both IV and via oral gavage. The results from this study indicate that the toxic alkaloids in larkspurs undergo flip-flop kinetics, meaning the rate of absorption of the alkaloids is slower than the rate of elimination. The implications of flip-flop kinetics in treating animals poisoned by larkspur is discussed. Published by Elsevier Ltd.

Adaptive prospective ECG-triggered sequence coronary angiography in dual-source CT without heart rate control: Image quality and diagnostic performance.

PubMed

Pan, Chang-Jie; Qian, Nong; Wang, Tao; Tang, Xiao-Qiang; Xue, Yue-Jun

2013-02-01

The aim of this study was to evaluate the accuracy of using second generation dual-source CT (DSCT) to obtain high quality images and diagnostic performance and to reduce the radiation dose in adaptive prospective electrocardiography (ECG)-triggered sequence (CorAdSeq) CT coronary angiography (CTCA) without heart rate control. No prescan β-blockers were administered. Un-enhanced CT and CTCA with adaptive prospective CorAdSeq scanning without heart rate control were performed in 683 consecutive patients divided into two body mass index (BMI) groups: BMI <25 kg/m(2) (group A, n=412) and BMI ≥25 kg/m(2) (group B, n=271). The image quality and quantitative stenosis of all coronary segments with a diameter ≥1 mm were assessed. The mean heart rate (MHR), heart rate variability (HRV) and radiation dose values were recorded. In 426 cases, the diagnostic performance was evaluated using quantitative conventional coronary angiography as the reference standard. Diagnostic image quality was obtained in 98.5% of segments in group A and in 98.8% of segments in group B, with no significant differences between the groups. No correlations were observed between the image quality score and MHR or HRV (P=0.492, P=0.564, respectively). The effective radiation doses in groups A and B were 2.57±1.01 mSv and 6.36±1.88 mSv, respectively. The sensitivities and specificities of diagnosing coronary heart disease per patient were 99.6% and 97.8% in group A and 99.5% and 97.5% in group B, respectively (P>0.05). Adaptive prospective CorAdSeq scanning, without heart rate control, by second generation DSCT had a high image quality and diagnostic performance for coronary artery stenosis with lower radiation doses.

Musculoskeletal imaging with a prototype photon-counting detector.

PubMed

Gruber, M; Homolka, P; Chmeissani, M; Uffmann, M; Pretterklieber, M; Kainberger, F

2012-01-01

To test a digital imaging X-ray device based on the direct capture of X-ray photons with pixel detectors, which are coupled with photon-counting readout electronics. The chip consists of a matrix of 256 × 256 pixels with a pixel pitch of 55 μm. A monolithic image of 11.2 cm × 7 cm was obtained by the consecutive displacement approach. Images of embalmed anatomical specimens of eight human hands were obtained at four different dose levels (skin dose 2.4, 6, 12, 25 μGy) with the new detector, as well as with a flat-panel detector. The overall rating scores for the evaluated anatomical regions ranged from 5.23 at the lowest dose level, 6.32 at approximately 6 μGy, 6.70 at 12 μGy, to 6.99 at the highest dose level with the photon-counting system. The corresponding rating scores for the flat-panel detector were 3.84, 5.39, 6.64, and 7.34. When images obtained at the same dose were compared, the new system outperformed the conventional DR system at the two lowest dose levels. At the higher dose levels, there were no significant differences between the two systems. The photon-counting detector has great potential to obtain musculoskeletal images of excellent quality at very low dose levels.

A phase I study of cabazitaxel in combination with platinum and 5-fluorouracil (PF) in locally advanced squamous cell carcinoma of head and neck (LA-SCCHN).

PubMed

Camille, Nadia; Rozehnal, John; Roy, Elizabeth; Uczkowski, Dariusz; Olson, Ashely; Genden, Eric; Teng, Marita; Bakst, Richard; Gupta, Vishal; Posner, Marshall; Misiukiewicz, Krzysztof

2017-08-01

There is a clinical need to improve outcomes for patients with locally advanced squamous cell carcinoma of the head and neck (LA-SCCHN), especially in Human Papilloma Virus (HPV) negative and HPV positive subtypes with a significant history of tobacco use. In animal models bearing SCCHN, Cabazitaxel showed an excellent response rate compared to docetaxel and might prove useful in treatment of patients. The primary objective of this study was to determine the dose-limiting toxicity (DLT) and maximum tolerated dose (MTD) of cabazitaxel when combined with cisplatin and 5-fluorouracil (PF) in induction chemotherapy (IC) for patients with SCCHN. Cabazitaxel-PF IC administered in 3 cycles (each 21 days) followed by concurrent chemoradiation (CRT) or surgery has been evaluated to assess overall response rate (ORR) and progression-free survival (PFS) in this population. This phase I study employed a standard 3+3 design. DLT was defined as grade 4 or 5 toxicity or grade 3 toxicity lasting >7days. Out of 40 consented patients with stage IV, curable, previously untreated, LA-SCHHN and poor prognosis, 35 (32M, 3F) were enrolled and evaluated for toxicity: 19 oropharynx, 10 larynx, 2 oral cancer, 1 nasopharynx and 3 hypopharynx. Five dose levels of cabazitaxel (10, 12.5, 15, 17.5 and 20mg/m 2 ) were tested in combination with cisplatin 100mg/m 2 and 5-fluorouracil (5-FU) 800mg/m 2 /d×4days. Dose escalation for cabazitaxel was terminated upon the occurrences of 2 DLTs and the establishment of MTD. Cabazitaxel was then further escalated with cisplatin 75mg/m 2 and 5-FU 800mg/m 2 /d×4days in the subsequent 3 dose levels (17.5, 20 and 22.5mg/m 2 ). In the expansion cohort, 9 patients were enrolled at the 22.5mg/m 2 dose level. Following 3 cycles of IC, patients were evaluated for clinical, radiographic, and pathologic response to cabazitaxel-PF before beginning CRT or surgery. There were two DLTs (grade 4 hyperuricemia; neutropenic fever, sepsis, and grade 4 thrombocytopenia) among 2 patients in cohort 5 at the dose of 20mg/m 2 of cabazitaxel. There were no DLTs reported with cohorts using a lower dose of cisplatin, even in the expansion cohort. The study was stopped at the dose of 22.5mg/m 2 in accordance with the initial study design. With 33 evaluable patients for response, the Overall Response Rate (ORR) rate was 57.6%: 9.1% Complete Responses (CR) and 48.5% Partial Responses (PR) were noted. The recommended phase II dose for cabazitaxel in combination with cisplatin 75mg/m 2 and 5-FU 800mg/m 2 /d×4days is 22.5mg/m 2 and for cisplatin 100mg/m 2 and 5-FU 800mg/m 2 /d×4days is 17.5mg/m 2 . With a median follow-up of 39months, PFS for the entire non-metastatic population at 3years was approximately 58%. Copyright © 2017 Elsevier Ltd. All rights reserved.

Evaluation of an X-Ray Dose Profile Derived from an Optically Stimulated Luminescent Dosimeter during Computed Tomographic Fluoroscopy.

PubMed

Hasegawa, Hiroaki; Sato, Masanori; Tanaka, Hiroshi

2015-01-01

The purpose of this study was to evaluate scatter radiation dose to the subject surface during X-ray computed tomography (CT) fluoroscopy using the integrated dose ratio (IDR) of an X-ray dose profile derived from an optically stimulated luminescent (OSL) dosimeter. We aimed to obtain quantitative evidence supporting the radiation protection methods used during previous CT fluoroscopy. A multislice CT scanner was used to perform this study. OSL dosimeters were placed on the top and the lateral side of the chest phantom so that the longitudinal direction of dosimeters was parallel to the orthogonal axis-to-slice plane for measurement of dose profiles in CT fluoroscopy. Measurement of fluoroscopic conditions was performed at 120 kVp and 80 kVp. Scatter radiation dose was evaluated by calculating the integrated dose determined by OSL dosimetry. The overall percent difference of the integrated doses between OSL dosimeters and ionization chamber was 5.92%. The ratio of the integrated dose of a 100-mm length area to its tails (-50 to -6 mm, 50 to 6 mm) was the lowest on the lateral side at 80 kVp and the highest on the top at 120 kVp. The IDRs for different measurement positions were larger at 120 kVp than at 80 kVp. Similarly, the IDRs for the tube voltage between the primary X-ray beam and scatter radiation was larger on the lateral side than on the top of the phantom. IDR evaluation suggested that the scatter radiation dose has a high dependence on the position and a low dependence on tube voltage relative to the primary X-ray beam for constant dose rate fluoroscopic conditions. These results provided quantitative evidence supporting the radiation protection methods used during CT fluoroscopy in previous studies.

Evaluation of an X-Ray Dose Profile Derived from an Optically Stimulated Luminescent Dosimeter during Computed Tomographic Fluoroscopy

PubMed Central

Hasegawa, Hiroaki; Sato, Masanori; Tanaka, Hiroshi

2015-01-01

The purpose of this study was to evaluate scatter radiation dose to the subject surface during X-ray computed tomography (CT) fluoroscopy using the integrated dose ratio (IDR) of an X-ray dose profile derived from an optically stimulated luminescent (OSL) dosimeter. We aimed to obtain quantitative evidence supporting the radiation protection methods used during previous CT fluoroscopy. A multislice CT scanner was used to perform this study. OSL dosimeters were placed on the top and the lateral side of the chest phantom so that the longitudinal direction of dosimeters was parallel to the orthogonal axis-to-slice plane for measurement of dose profiles in CT fluoroscopy. Measurement of fluoroscopic conditions was performed at 120 kVp and 80 kVp. Scatter radiation dose was evaluated by calculating the integrated dose determined by OSL dosimetry. The overall percent difference of the integrated doses between OSL dosimeters and ionization chamber was 5.92%. The ratio of the integrated dose of a 100-mm length area to its tails (−50 to −6 mm, 50 to 6 mm) was the lowest on the lateral side at 80 kVp and the highest on the top at 120 kVp. The IDRs for different measurement positions were larger at 120 kVp than at 80 kVp. Similarly, the IDRs for the tube voltage between the primary X-ray beam and scatter radiation was larger on the lateral side than on the top of the phantom. IDR evaluation suggested that the scatter radiation dose has a high dependence on the position and a low dependence on tube voltage relative to the primary X-ray beam for constant dose rate fluoroscopic conditions. These results provided quantitative evidence supporting the radiation protection methods used during CT fluoroscopy in previous studies. PMID:26151914

Quantitative evaluation of 3D dosimetry for stereotactic volumetric‐modulated arc delivery using COMPASS

PubMed Central

Manigandan, Durai; Karrthick, Karukkupalayam Palaniappan; Sambasivaselli, Raju; Senniandavar, Vellaingiri; Ramu, Mahendran; Rajesh, Thiyagarajan; Lutz, Muller; Muthukumaran, Manavalan; Karthikeyan, Nithyanantham; Tejinder, Kataria

2014-01-01

The purpose of this study was to evaluate quantitatively the patient‐specific 3D dosimetry tool COMPASS with 2D array MatriXX detector for stereotactic volumetric‐modulated arc delivery. Twenty‐five patients CT images and RT structures from different sites (brain, head & neck, thorax, abdomen, and spine) were taken from CyberKnife Multiplan planning system for this study. All these patients underwent radical stereotactic treatment in CyberKnife. For each patient, linac based volumetric‐modulated arc therapy (VMAT) stereotactic plans were generated in Monaco TPS v3.1 using Elekta Beam Modulator MLC. Dose prescription was in the range of 5–20 Gy per fraction. Target prescription and critical organ constraints were tried to match the delivered treatment plans. Each plan quality was analyzed using conformity index (CI), conformity number (CN), gradient Index (GI), target coverage (TC), and dose to 95% of volume (D95). Monaco Monte Carlo (MC)‐calculated treatment plan delivery accuracy was quantitatively evaluated with COMPASS‐calculated (CCA) dose and COMPASS indirectly measured (CME) dose based on dose‐volume histogram metrics. In order to ascertain the potential of COMPASS 3D dosimetry for stereotactic plan delivery, 2D fluence verification was performed with MatriXX using MultiCube phantom. Routine quality assurance of absolute point dose verification was performed to check the overall delivery accuracy. Quantitative analyses of dose delivery verification were compared with pass and fail criteria of 3 mm and 3% distance to agreement and dose differences. Gamma passing rate was compared with 2D fluence verification from MatriXX with MultiCube. Comparison of COMPASS reconstructed dose from measured fluence and COMPASS computed dose has shown a very good agreement with TPS calculated dose. Each plan was evaluated based on dose volume parameters for target volumes such as dose at 95% of volume (D95) and average dose. For critical organs dose at 20% of volume (D20), dose at 50% of volume (D50), and maximum point doses were evaluated. Comparison was carried out using gamma analysis with passing criteria of 3 mm and 3%. Mean deviation of 1.9%±1% was observed for dose at 95% of volume (D95) of target volumes, whereas much less difference was noticed for critical organs. However, significant dose difference was noticed in two cases due to the smaller tumor size. Evaluation of this study revealed that the COMPASS 3D dosimetry is efficient and easy to use for patient‐specific QA of VMAT stereotactic delivery. 3D dosimetric QA with COMPASS provides additional degrees of freedom to check the high‐dose modulated stereotactic delivery with very high precision on patient CT images. PACS numbers: 87.55.Qr, 87.56.Fc PMID:25679152

SU-F-T-587: Quality Assurance of Stereotactic Radiosurgery (SRS) and Stereotactic Body Radiation Therapy (SBRT) for Patient Specific Plans: A Comparison Between MATRIXX and Delta4 QA Devices

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

Tsai, YC; Lu, SH; Chen, LH

2016-06-15

Purpose: Patient-specific quality assurance (QA) is necessary to accurately deliver high dose radiation to the target, especially for stereotactic radiosurgery (SRS) and stereotactic body radiation therapy (SBRT). Unlike previous 2 dimensional (D) array QA devices, Delta{sup 4} can verify the dose delivery in 3D. In this study, the difference between calculated and measured dose distribution was compared with two QA devices (MATRIXX and Delta{sup 4}) to evaluate the delivery accuracy. Methods: Twenty-seven SRS/SBRT plans with VMAT were verified with point-dose and dose-map analysis. We use an ion chamber (A1SL, 0.053cc) for point-dose measurement. For verification of the dose map, themore » differences between the calculated and measured doses were analyzed with a gamma index using MATRIXX and Delta{sup 4} devices. The passing criteria for gamma evaluation were set at 3 mm for distance-to-agreement (DTA) and 3% for dose-difference. A gamma index less than 1 was defined as the verification passing the criteria and satisfying at least 95% of the points. Results: The mean prescribed dose and fraction was 40 ± 14.41 Gy (range: 16–60) and 10 ± 2.35 fractions (range: 1–8), respectively. In point dose analysis, the differences between the calculated and measured doses were all less than 5% (mean: 2.12 ± 1.13%; range: −0.55% to 4.45%). In dose-map analysis, the average passing rates were 99.38 ± 0.96% (range: 95.31–100%) and 100 ± 0.12% (range: 99.5%–100%) for MATRIXX and Delta{sup 4}, respectively. Even using criteria of 2%/2 mm, the passing rate of Delta{sup 4} was still more than 95% (mean: 99 ± 1.08%; range: 95.6%–100%). Conclusion: Both MATRIXX and Delta{sup 4} offer accurate and efficient verification for SRS/SBRT plans. The results measured by MATRIXX and Delta{sup 4} dosimetry systems are similar for SRS/SBRT performed with the VMAT technique.« less

SU-E-T-269: Quality Assurance of Spine Volumetric Modulated Arc Therapy with Flattening Filter Free Beams Using Gafchromic EBT3 Films

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

Choi, Y; Cho, B; Kwak, J

2014-06-01

Purpose: We implemented the Gafchromic film-based patient specific QA of volumetric modulated arc therapy (VMAT) with flattening-filter free (FFF) beams for spine metastases and validated the accuracy of fast arc delivery. Methods: EBT3 films and a homemade cylindrical QA phantom were employed for dosimetric verification of VMATs. For 14 FFF VMAT plans (10 with 10-MV FFF beams and 4 with 6-MV FFF beams), the doses were recalculated on the phantom and delivered by a TrueBeam STx accelerator equipped with a high-definition 120 leaf MLC. The EBT3 films were scanned using an Epson 10000XL scanner through the FilmQA Pro software. Allmore » the irradiated film images were converted to dose map using a calibration response curve. The resulting dose map of film measurement was compared with treatment plan and evaluated using gamma analysis with dose tolerance of 2% within 2 mm. In addition, the point-dose measurement in the phantom using an ion chamber was evaluated as a reference in a ratio of measured and planned doses. Results: The gamma pass rates averaged over all FFF plans for composite-field measurements were 96.0 ± 3.6% (88.9%–99.5%). When adopting a tolerance level of 3% - 3 mm, the gamma pass rates were improved with the ranges from 98% to 100%. In addition, dose profiles and dose distributions showed that spinal cord was protected by the rapid dose fall-off and by delivering the treatment with high precision. In point-dose measurements, the average differences between the measured and planned doses were 0.5% ± 1.0% of the prescription dose. Conclusion: We demonstrated that Gafchromic EBT3 film would be an effective patient-specific QA tool, especially for VMAT of spine SBRT with treatment of small fields and highly gradient dose distributions. The results of film QA verified that the dosimetric accuracy of spine SBRT utilizing RapidArc with FFF beams in our institution is reliable.« less

Evaluate an impact of incident alpha particle and gamma ray on human blood components: A comparison study

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

Ismail, Asaad H.; Yaba, Sardar P.; Ismail, Haider J.

An impact of alpha and gamma irradiation on human blood components have been evaluated and compared for healthy blood samples (male and females). Irradiation dose and time of irradiation calibrated and considered as a main comparison factors. Density of blood components measured for each in vitro irradiation before and after irradiation for males and females. Survey radiation dosimeter (Inspector Exp) and nuclear track detectors type CR-39 used to evaluate exposure dose rate and incident density of alpha particles, respectively. Experiment results verified that the irradiation of blood makes ionizing of blood components, either alpha or gamma irradiation dose, and themore » impacts of ionizing radiation were relativity for WBC, RBC, and PLT. Limited irradiation doses of 1-5 μSv/hr considered as a low radiation dose of alpha and gamma radiation sources ({sup 226}Ra, and {sup 137}Cs). Density of alpha particles accumulated on the blood surface was 34 (alpha particle/cm{sup 2}) for selected dose of incident alpha particle. Optimum value of irradiation dose and time of irradiation were 5 μSv/hr and 4 second for males and females. On the other hands, the values of irradiation dose and time of irradiation were 2.1 μSv/hr and 2 second for males and females for gamma irradiation. Thus, present results demonstrated that densities of RBC and WBC cells are capable of inducing reproduction in vitro for both type of irradiation. (authors)« less

A Multiple-Dose, Randomized, Double-Blind, Placebo-Controlled, Parallel-Group QT/QTc Study to Evaluate the Electrophysiologic Effects of THC/CBD Spray.

PubMed

Sellers, Edward M; Schoedel, Kerri; Bartlett, Cindy; Romach, Myroslava; Russo, Ethan B; Stott, Colin G; Wright, Stephen; White, Linda; Duncombe, Paul; Chen, Chien-Feng

2013-07-01

Delta-9-tetrahydrocannabinol (THC)/cannabidiol (CBD) oromucosal spray has proved efficacious in the treatment of spasticity in multiple sclerosis and chronic pain. A thorough QT/QTc study was performed to investigate the effects of THC/CBD spray on electrocardiogram (ECG) parameters in compliance with regulatory requirements, evaluating the effect of a recommended daily dose (8 sprays/day) and supratherapeutic doses (24 or 36 sprays/day) of THC/CBD spray on the QT/QTc interval in 258 healthy volunteers. The safety, tolerability, and pharmacokinetic profile of THC/CBD spray were also evaluated. Therapeutic and supratherapeutic doses of THC/CBD spray had no effect on cardiac repolarization with primary and secondary endpoints of QTcI and QTcF/QTcB, respectively, showing similar results. There was no indication of any effect on heart rate, atrioventricular conduction, or cardiac depolarization and no new clinically relevant morphological changes were observed. Overall, 19 subjects (25.0%) in the supratherapeutic (24/36 daily sprays of THC/CBD spray) dose group and one (1.6%) in the moxifloxacin group withdrew early due to intolerable AEs. Four psychiatric serious adverse events (AEs) in the highest dose group resulted in a reduction in the surpatherapeutic dose to 24 sprays/day. In conclusion, THC/CBD spray does not significantly affect ECG parameters. Additionally, THC/CBD spray is well tolerated at therapeutic doses with an AE profile similar to previous clinical studies. © The Author(s) 2013.

Efficacy and Safety of As-Needed, Post Bedtime Dosing with Indiplon in Insomnia Patients with Chronic Difficulty Maintaining Sleep

PubMed Central

Roth, Thomas; Zammit, Gary K.; Scharf, Martin B.; Farber, Robert

2007-01-01

Objective: To evaluate the efficacy and tolerability of immediate release indiplon capsules in patients with chronic insomnia using an “as-needed” dosing strategy in response to difficulty falling back to sleep following a middle of the night, nocturnal awakening. Methods: Adult outpatients (N=264; 71% female; age, 46 years) who met DSM-IV criteria for primary insomnia, with average total sleep time (TST) <6.5 hours and >8 nights in the past month with nocturnal awakenings, were randomized to 4 weeks of double-blind treatment with 10mg or 20mg indiplon capsules, or placebo. The primary endpoint was latency to sleep onset post-dosing after a middle of the night awakening (LSOpd). Secondary endpoints included patients' subjective assessment of total sleep time (sTSTpd). Next day residual effects were evaluated by a 100mm Visual Analog Scale (VAS) rating of sleepiness. Results: Both doses of indiplon significantly reduced LSOpd at all time-points. Compared to placebo (45.2 min), the 4-week least squares (LS) mean LSOpd was 36.5 min in the indiplon 10mg group (P=0.0023) and 34.4 min in the indiplon 20mg group (P<0.0001). The 4-week LS mean sTSTpd was higher in the indiplon 10mg group (253 min) and 20mg group (278 min) compared to placebo (229 min; P<0.01 for both comparisons). There was no increase observed in VAS ratings of next-day sleepiness for either dose of indiplon when compared to placebo. Indiplon was well-tolerated at both doses. Conclusions: Patients with chronic insomnia with nocturnal awakenings achieved significant and sustained improvement in sleep parameters while utilizing an as-needed post bedtime dosing strategy with indiplon capsules. Indiplon was well-tolerated, with no self-rated, next-day residual effects. Citation: Roth T; Zammit GK; Scharf MB; Farber R. Efficacy and safety of as-needed, post bedtime dosing with indiplon in insomnia patients with chronic difficulty maintaining sleep. SLEEP 2007;30(12):1731-1738. PMID:18246982

Immunological Effect of aGV Rabies Vaccine Administered Using the Essen and Zagreb Regimens: A Double-Blind, Randomized Clinical Trial.

PubMed

Miao, Li; Shi, Liwei; Yang, Yi; Yan, Kunming; Sun, Hongliang; Mo, Zhaojun; Li, Li

2018-04-01

This study evaluated the immunological effect of an aGV rabies virus strain using the Essen and Zagreb immunization programs. A total of 1,944 subjects were enrolled and divided into three groups: the Essen test group, Essen control group, and Zagreb test group. Neutralizing antibody levels and antibody seroconversion rates were determined at 7 and 14 days after the initial inoculations and then 14 days after the final inoculation in all of the subjects. The seroconversion rates for the Essen test group, Essen control group, and Zagreb test group, which were assessed 7 days after the first dosing in a susceptible population, were 35.74%, 26.92%, and 45.49%, respectively, and at 14 days, the seroconversion rates in this population were 100%, 100%, and 99.63%, respectively. At 14 days after the final dosing, the seroconversion rates were 100% in all three of the groups. The neutralizing serum antibody levels of the Essen test group, Essen control group, and Zagreb test group at 7 days after the first dosing in the susceptible population were 0.37, 0.26, and 0.56 IU/mL, respectively, and at 14 days after the initial dosing, these levels were 16.71, 13.85, and 16.80 IU/mL. At 14 days after the final dosing, the neutralizing antibody levels were 22.9, 16.3, and 18.62 IU/mL, respectively. The results of this study suggested that the aGV rabies vaccine using the Essen program resulted in a good serum immune response, and the seroconversion rates and the neutralizing antibody levels generated with the Zagreb regimen were higher than those with the Essen regimen when measured 7 days after the first dose.

Effectiveness of using low rate fluoroscopy to reduce an examiner's radiation dose during lumbar nerve root block.

PubMed

Yamane, Kentaro; Kai, Nobuo; Mazaki, Tetsuro; Miyamoto, Tadashi; Matsushita, Tomohiro

2018-06-13

Long-term exposure to radiation can lead to gene mutations and increase the risk of cancer. Low rate fluoroscopy has the potential to reduce the radiation exposure for both the examiner and the patient during various fluoroscopic procedures. The purpose of this study was to evaluate the impact of low rate fluoroscopy on reducing an examiner's radiation dose during nerve root block. A total of 101 lumbar nerve root block examinations were performed at our institute during a 6-month period. During the first 3 months, low rate fluoroscopy was performed at 7.5 frames/s (FPS) in 54 examinations, while 47 were performed at 15 FPS during the last 3 months. The examiner wore a torso protector, a neck protector, radiation protection gloves, and radiation protection glasses. Optically stimulated luminescence (OSL) dosimeter badges were placed on both the inside and the outside of each protector. The dosimeters were exchanged every month. Radiation doses (mSv) were measured as the integrated radiation quantity every month from the OSL dosimeters. The effective and equivalent doses for the hands, skin, and eyes were investigated. The mean monthly equivalent doses were significantly lower both inside and outside the hand protector for the 7.5 FPS versus 15 FPS (inside; P = 0.021, outside; P = 0.024). There were no significant differences between the two groups for the mean monthly calculated effective dose for each protector's condition. Radiation exposure was significantly reduced for the skin on the examiner's hand when using low rate fluoroscopy at 7.5 FPS, with no noticeable decrease in image quality or prolonged fluoroscopy time. Copyright © 2018. Published by Elsevier B.V.

High dose rate brachytherapy for oral cancer

PubMed Central

YamazakI, Hideya; Yoshida, Ken; Yoshioka, Yasuo; Shimizutani, Kimishige; Furukawa, Souhei; Koizumi, Masahiko; Ogawa, Kazuhiko

2013-01-01

Brachytherapy results in better dose distribution compared with other treatments because of steep dose reduction in the surrounding normal tissues. Excellent local control rates and acceptable side effects have been demonstrated with brachytherapy as a sole treatment modality, a postoperative method, and a method of reirradiation. Low-dose-rate (LDR) brachytherapy has been employed worldwide for its superior outcome. With the advent of technology, high-dose-rate (HDR) brachytherapy has enabled health care providers to avoid radiation exposure. This therapy has been used for treating many types of cancer such as gynecological cancer, breast cancer, and prostate cancer. However, LDR and pulsed-dose-rate interstitial brachytherapies have been mainstays for head and neck cancer. HDR brachytherapy has not become widely used in the radiotherapy community for treating head and neck cancer because of lack of experience and biological concerns. On the other hand, because HDR brachytherapy is less time-consuming, treatment can occasionally be administered on an outpatient basis. For the convenience and safety of patients and medical staff, HDR brachytherapy should be explored. To enhance the role of this therapy in treatment of head and neck lesions, we have reviewed its outcomes with oral cancer, including Phase I/II to Phase III studies, evaluating this technique in terms of safety and efficacy. In particular, our studies have shown that superficial tumors can be treated using a non-invasive mold technique on an outpatient basis without adverse reactions. The next generation of image-guided brachytherapy using HDR has been discussed. In conclusion, although concrete evidence is yet to be produced with a sophisticated study in a reproducible manner, HDR brachytherapy remains an important option for treatment of oral cancer. PMID:23179377

High dose rate brachytherapy for oral cancer.

PubMed

Yamazaki, Hideya; Yoshida, Ken; Yoshioka, Yasuo; Shimizutani, Kimishige; Furukawa, Souhei; Koizumi, Masahiko; Ogawa, Kazuhiko

2013-01-01

Brachytherapy results in better dose distribution compared with other treatments because of steep dose reduction in the surrounding normal tissues. Excellent local control rates and acceptable side effects have been demonstrated with brachytherapy as a sole treatment modality, a postoperative method, and a method of reirradiation. Low-dose-rate (LDR) brachytherapy has been employed worldwide for its superior outcome. With the advent of technology, high-dose-rate (HDR) brachytherapy has enabled health care providers to avoid radiation exposure. This therapy has been used for treating many types of cancer such as gynecological cancer, breast cancer, and prostate cancer. However, LDR and pulsed-dose-rate interstitial brachytherapies have been mainstays for head and neck cancer. HDR brachytherapy has not become widely used in the radiotherapy community for treating head and neck cancer because of lack of experience and biological concerns. On the other hand, because HDR brachytherapy is less time-consuming, treatment can occasionally be administered on an outpatient basis. For the convenience and safety of patients and medical staff, HDR brachytherapy should be explored. To enhance the role of this therapy in treatment of head and neck lesions, we have reviewed its outcomes with oral cancer, including Phase I/II to Phase III studies, evaluating this technique in terms of safety and efficacy. In particular, our studies have shown that superficial tumors can be treated using a non-invasive mold technique on an outpatient basis without adverse reactions. The next generation of image-guided brachytherapy using HDR has been discussed. In conclusion, although concrete evidence is yet to be produced with a sophisticated study in a reproducible manner, HDR brachytherapy remains an important option for treatment of oral cancer.

Efficacy of a Radiation Absorbing Shield in Reducing Dose to the Interventionalist During Peripheral Endovascular Procedures: A Single Centre Pilot Study

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

Power, S.; Mirza, M.; Thakorlal, A.

PurposeThis prospective pilot study was undertaken to evaluate the feasibility and effectiveness of using a radiation absorbing shield to reduce operator dose from scatter during lower limb endovascular procedures.Materials and MethodsA commercially available bismuth shield system (RADPAD) was used. Sixty consecutive patients undergoing lower limb angioplasty were included. Thirty procedures were performed without the RADPAD (control group) and thirty with the RADPAD (study group). Two separate methods were used to measure dose to a single operator. Thermoluminescent dosimeter (TLD) badges were used to measure hand, eye, and unshielded body dose. A direct dosimeter with digital readout was also used tomore » measure eye and unshielded body dose. To allow for variation between control and study groups, dose per unit time was calculated.ResultsTLD results demonstrated a significant reduction in median body dose per unit time for the study group compared with controls (p = 0.001), corresponding to a mean dose reduction rate of 65 %. Median eye and hand dose per unit time were also reduced in the study group compared with control group, however, this was not statistically significant (p = 0.081 for eye, p = 0.628 for hand). Direct dosimeter readings also showed statistically significant reduction in median unshielded body dose rate for the study group compared with controls (p = 0.037). Eye dose rate was reduced for the study group but this was not statistically significant (p = 0.142).ConclusionInitial results are encouraging. Use of the shield resulted in a statistically significant reduction in unshielded dose to the operator’s body. Measured dose to the eye and hand of operator were also reduced but did not reach statistical significance in this pilot study.« less

SU-E-J-274: Responses of Medulloblastoma Cells to Radiation Dosimetric Parameters in Intensity-Modulated Radiation Therapy

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

Park, J; Molecular Imaging Program at Stanford, Stanford, CA; Bio-X Program, Stanford, CA

2015-06-15

Purpose: To evaluate radiation responses of the medulloblastoma cell line Daoy in intensity-modulated radiation therapy (IMRT), quantitative variations to variable radiation dosimetic parameters were tracked by bioluminescent images (BLIs). Methods: The luciferase and green fluorescent protein positive Daoy cells were cultured on dishes. The medulloblastoma cells irradiated to different dose rate, interval of fractionated doses, field margin and misalignment, and dose uniformity in IMRT were monitored using bioluminescent images. The cultured cells were placed into a dedicated acrylic phantom to deliver intensity-modulated fluences and calculate accurate predicted dose distribution. The radiation with dose rate from 0.5 Gy/min to 15 Gy/minmore » was irradiated by adjusting monitor unit per minute and source-to-surface distances. The intervals of fractionated dose delivery were changed considering the repair time of double strand breaks (DSB) revealed by straining of gamma-H2AX.The effect of non-uniform doses on the cells were visualized by registering dose distributions and BLIs. The viability according to dosimetric parameters was correlated with bioluminescent intensities for cross-check of radiation responses. Results: The DSB and cell responses due to the first fractionated dose delivery significantly affected final tumor control rather than other parameters. The missing tumor volumes due to the smaller field margin than the tumor periphery or field misalignment caused relapse of cell responses on BLIs. The dose rate and gradient had effect on initial responses but could not bring out the distinguishable killing effect on cancer cells. Conclusion: Visualized and quantified bioluminescent images were useful to correlate the dose distributions with spatial radiation effects on cells. This would derive the effective combination of dose delivery parameters and fractionation. Radiation responses in particular IMRT configuration could be reflected to image based-dose re-optimization.« less

A randomized, double-blind, placebo-controlled, dose-ranging study of lisdexamfetamine dimesylate augmentation for major depressive disorder in adults with inadequate response to antidepressant therapy

PubMed Central

Richards, Cynthia; Iosifescu, Dan V; Mago, Rajnish; Sarkis, Elias; Reynolds, James; Geibel, Brooke; Dauphin, Matthew

2017-01-01

Background: This randomized, double-blind, placebo-controlled study evaluated dose-response relationships of lisdexamfetamine dimesylate when used as augmentation for major depressive disorder in individuals exhibiting inadequate responses to antidepressant monotherapy. Methods: Eligible adults (18–65 years) were assigned to antidepressant monotherapy (escitalopram or venlafaxine extended-release) plus lisdexamfetamine dimesylate-matching placebo during an eight-week single-blind lead-in phase. Participants meeting randomization criteria were randomized (1:1:1:1:1) to eight weeks of lisdexamfetamine dimesylate (10, 30, 50, or 70 mg) or placebo while maintaining antidepressant therapy. Dose-responses for changes from augmentation baseline to week 16/early termination for Montgomery-Åsberg Depression Rating Scale total score (primary efficacy endpoint) and vital signs (systolic and diastolic blood pressure and pulse) were assessed using multiple comparisons procedures with modeling. Results: For Montgomery-Åsberg Depression Rating Scale total score change, no significant dose-responses were observed for any candidate dose-response curve (all p>0.10). In the dose-response evaluable population, least squares mean (90% confidence interval) treatment differences versus placebo for Montgomery-Åsberg Depression Rating Scale total score change at week 16 were −1.4 (−3.9, 1.2), 0.1 (−2.5, 2.7), −0.7 (−3.4, 2.0), and −0.9 (−3.5, 1.6) with 10, 30, 50, and 70 mg lisdexamfetamine dimesylate, respectively. For all vital sign parameters, lisdexamfetamine dimesylate exhibited significant dose-responses for all candidate dose-response curves (all p<0.10), with increases observed as lisdexamfetamine dimesylate dose increased; a linear relationship provided the best fit. Mean±standard deviation changes from augmentation baseline for systolic and diastolic blood pressure and pulse at week 16/early termination were −0.7±9.90 and −0.3±7.24 mm Hg and 0.2±10.57 bpm with placebo and were 1.9±9.47 and 0.8±7.40 mm Hg and 3.6±9.74 bpm with lisdexamfetamine dimesylate (all doses combined). The safety and tolerability profile of lisdexamfetamine dimesylate was consistent with previous studies. Conclusions: Lisdexamfetamine dimesylate augmentation did not provide benefit over placebo in adults with inadequate responses to antidepressant monotherapy based on the assessed efficacy measures. PMID:28857719

Acrosin activity is a suitable indicator of boar semen preservation at 17 °C when increasing environmental temperature and radiation.

PubMed

Pinart, E; Yeste, M; Puigmulé, M; Barrera, X; Bonet, S

2013-08-01

The effect of increasing environmental temperature and radiation on the sperm quality and the field fertility of refrigerated seminal doses from AI boars (N = 30) was analyzed throughout four experimental months (from March through June). In each experimental month, analyses of sperm quality were performed at days 0, 1, 3, 5, 7, and 9 of refrigeration of seminal doses; pregnancy rate and litter size were evaluated using double monospermic inseminations of multiparous female animals using seminal doses at Days 1 to 2 and Days 3 to 4 of refrigeration. Sperm quality was assessed from the evaluation of conventional parameters of sperm concentration, sperm motility, sperm morphology, and sperm viability, and capacitation parameters of membrane lipid disorder, intracellular calcium content, and acrosin activity. Results showed that sperm quality of boar seminal doses was negatively affected by increasing temperature and radiation, which resulted in significantly decreased sperm motility and viability, acrosin activity, pregnancy rate, and litter size, and significantly increased intracellular calcium levels in the trials performed in June. In any experimental month, aging of refrigerated doses was associated with the progressive increase of intracellular calcium levels and inactivation of acrosin, that began from Day 5 of storage in the trials performed in March and April, from Day 3 in those of May, and from Day 0 in those of June. Among the sperm parameters analyzed, only acrosin activity exhibited a clearly differentiated pattern in association with increasing temperature and radiation, and a significant correlation with pregnancy rate and litter size. These results highlighted the potential role of acrosin activity as an indicator of boar sperm preservation at 17 °C in boars. Copyright © 2013 Elsevier Inc. All rights reserved.

Hematopoietic responses under protracted exposures to low daily dose gamma irradiation.

PubMed

Seed, T M; Fritz, T E; Tolle, D V; Jackson, W E

2002-01-01

In attempting to evaluate the possible health consequences of chronic ionizing radiation exposure during extended space travel (e.g., Mars Mission), ground-based experimental studies of the clinical and pathological responses of canines under low daily doses of 60Co gamma irradiation (0.3-26.3 cGy d-1) have been examined. Specific reference was given to responses of the blood forming system. Results suggest that the daily dose rate of 7.5 cGy d-1 represents a threshold below which the hematopoietic system can retain either partial or full trilineal cell-producing capacity (erythropoiesis, myelopoiesis, and megakaryopoiesis) for extended periods of exposure (>1 yr). Trilineal capacity was fully retained for several years of exposure at the lowest dose-rate tested (0.3 cGy d-1) but was completely lost within several hundred days at the highest dose-rate (26.3 cGy d-1). Retention of hematopoietic capacity under chronic exposure has been demonstrated to be mediated by hematopoietic progenitors with acquired radioresistance and repair functions, altered cytogenetics, and cell-cycle characteristics. Radiological, biological, and temporal parameters responsible for these vital acquisitions by hematopoietic progenitors have been partially characterized. These parameters, along with threshold responses, are described and discussed in relation to potential health risks of the space traveler under chronic stress of low-dose irradiation. Published by Elsevier Science Ltd on behalf of COSPAR.

The impact of variation in scaling factors on the estimation of ...

EPA Pesticide Factsheets

Many physiologically based pharmacokinetic (PBPK) models include values for metabolic rate parameters extrapolated from in vitro metabolism studies using scaling factors such as mg of microsomal protein per gram of liver (MPPGL) and liver mass (FVL). Variation in scaling factor values impacts metabolic rate parameter estimates (Vmax) and hence estimates of internal dose used in dose response analysis. The impacts of adult human variation in MPPGL and FVL on estimates of internal dose were assessed using a human PBPK model for BDCM for several internal dose metrics for two exposure scenarios (single 0.25 liter drink of water or 10 minute shower) under plausible (5 micrograms/L) and high level (20 micrograms/L) water concentrations. For both concentrations, all internal dose metrics were changed less than 5% for the showering scenario (combined inhalation and dermal exposure). In contrast, a 27-fold variation in area under the curve for BDCM in venous blood was observed at both oral exposure concentrations, whereas total amount of BDCM metabolized in liver was relatively unchanged. This analysis demonstrates that variability in the scaling factors used for in vitro to in vivo extrapolation (IVIVE) for metabolic rate parameters can have a significant route-dependent impact on estimates of internal dose under environmentally relevant exposure scenarios. This indicates the need to evaluate both uncertainty and variability for scaling factors used for IVIVE. Sca

The consistency of Fletcher-Suit applicator geometry and of the rectal probe’s position in high dose rate brachytherapy treatment fraction of cervix carcinoma

PubMed Central

2009-01-01

Purpose The dose values computed with the treatment planning system and the in vivo dose measurements with semiconductor detectors in rectum during the high dose rate brachytherapy treatment fraction of the cervix carcinoma are occasionally significantly different. We’ve investigated the consistency of the Fletcher-Suit applicator geometry and the in vivo rectal probe’s position stability during the high dose rate brachytherapy treatment fraction. Material and methods The patient lied in a lithotomic position during a biplane reconstruction images, throughout the treatment planning and dose administration. We obtained post-treatment reconstruction images and prepared a post-treatment plan. The amount of 14 treatment fractions of 10 patients were considered in the study. Two methods were applied: evaluation of the difference of reconstructed pre-treatment and post-treatment applicator points and rectal probe’s detectors being relevant to the co-ordinate system fixed to the applicator, and estimation of applicators and rectal probe’s reallocation with respect to the pelvic bones with registration of pre- and post-treatment reconstruction images. Results We’ve experienced good consistency in the Fletcher-Suit applicator geometry in all treatment fractions. 70% of them presented small variation in the rectal probe’s position, while the rest showed significant shift in the applicator or rectal probe’s position with regard to the pelvic bones. PMID:27807458

Clinical application of a OneDose MOSFET for skin dose measurements during internal mammary chain irradiation with high dose rate brachytherapy in carcinoma of the breast.

PubMed

Kinhikar, Rajesh A; Sharma, Pramod K; Tambe, Chandrashekhar M; Mahantshetty, Umesh M; Sarin, Rajiv; Deshpande, Deepak D; Shrivastava, Shyam K

2006-07-21

In our earlier study, we experimentally evaluated the characteristics of a newly designed metal oxide semiconductor field effect transistor (MOSFET) OneDose in-vivo dosimetry system for Ir-192 (380 keV) energy and the results were compared with thermoluminescent dosimeters (TLDs). We have now extended the same study to the clinical application of this MOSFET as an in-vivo dosimetry system. The MOSFET was used during high dose rate brachytherapy (HDRBT) of internal mammary chain (IMC) irradiation for a carcinoma of the breast. The aim of this study was to measure the skin dose during IMC irradiation with a MOSFET and a TLD and compare it with the calculated dose with a treatment planning system (TPS). The skin dose was measured for ten patients. All the patients' treatment was planned on a PLATO treatment planning system. TLD measurements were performed to compare the accuracy of the measured results from the MOSFET. The mean doses measured with the MOSFET and the TLD were identical (0.5392 Gy, 15.85% of the prescribed dose). The mean dose was overestimated by the TPS and was 0.5923 Gy (17.42% of the prescribed dose). The TPS overestimated the skin dose by 9% as verified by the MOSFET and TLD. The MOSFET provides adequate in-vivo dosimetry for HDRBT. Immediate readout after irradiation, small size, permanent storage of dose and ease of use make the MOSFET a viable alternative for TLDs.

Influence of form structure on the anesthesia preoperative evaluation.

PubMed

Marco, Alan P; Buchman, Debra; Lancz, Colleen

2003-09-01

To determine the impact of changes in form design on the capture of administrative and clinical data elements. Randomized retrospective chart review. Academic health center. Patients undergoing surgical procedures in the operating rooms at Medical College Hospital. The principal intervention was the implementation of a newly designed anesthesiology preoperative evaluation form with the intent to improve data capture. Charts were reviewed for the presence or absence of the following indicators: Addressograph Stamp, Proposed Surgery, Current Medications, Medication Doses/Frequency, Allergies, ASA Physical Status, Anesthesia Plan, Attending Note, and fasting (NPO) Status. Completion of Proposed Surgery and ASA Physical Status was lower for the structured form. Completion of Attending Notes was higher with the new form. Medication Doses were more often completed, but they remained below desired levels on the new form. Design of a form can have a significant impact on the completion rate of form elements. Visual cues such as a labeled space for medication doses may improve the completion of these elements. Design layout can also have an influence on completion. In this case, changes to the layout may have impeded the completion rate for ASA Physical Status.

Reduced-Nicotine Cigarettes in Young Smokers: Impact of Nicotine Metabolism on Nicotine Dose Effects.

PubMed

Faulkner, Paul; Ghahremani, Dara G; Tyndale, Rachel F; Cox, Chelsea M; Kazanjian, Ari S; Paterson, Neil; Lotfipour, Shahrdad; Hellemann, Gerhard S; Petersen, Nicole; Vigil, Celia; London, Edythe D

2017-07-01

The use of cigarettes delivering different nicotine doses allows evaluation of the contribution of nicotine to the smoking experience. We compared responses of 46 young adult smokers to research cigarettes, delivering 0.027, 0.110, 0.231, or 0.763 mg nicotine, and conventional cigarettes. On five separate days, craving, withdrawal, affect, and sustained attention were measured after overnight abstinence and again after smoking. Participants also rated each cigarette, and the nicotine metabolite ratio (NMR) was used to identify participants as normal or slow metabolizers. All cigarettes equally alleviated craving, withdrawal, and negative affect in the whole sample, but normal metabolizers reported greater reductions of craving and withdrawal than slow metabolizers, with dose-dependent effects. Only conventional cigarettes and, to a lesser degree, 0.763-mg nicotine research cigarettes increased sustained attention. Finally, there were no differences between ratings of lower-dose cigarettes, but the 0.763-mg cigarettes and (even more so) conventional cigarettes were rated more favorably than lower-dose cigarettes. The findings indicate that smoking-induced relief of craving and withdrawal reflects primarily non-nicotine effects in slow metabolizers, but depends on nicotine dose in normal metabolizers. By contrast, relief of withdrawal-related attentional deficits and cigarette ratings depend on nicotine dose regardless of metabolizer status. These findings have bearing on the use of reduced-nicotine cigarettes to facilitate smoking cessation and on policy regarding regulation of nicotine content in cigarettes. They suggest that normal and slow nicotine metabolizers would respond differently to nicotine reduction in cigarettes, but that irrespective of metabolizer status, reductions to <0.763 mg/cigarette may contribute to temporary attentional deficits.

Comparison of two neonatal indomethacin protocols: efficacy and outcome for patent ductus arteriosus closure.

PubMed

Rosito, G; Sum, K; Chorne, N

2010-10-01

Indomethacin, a non-selective inhibitor of prostaglandin synthesis, is the gold standard treatment for patent ductus arteriosus (PDA). Indomethacin has been shown to permanently close the ductus and when given prophylactically, it reduces the incidence of PDA (1, 2). This study compares PDA closure and surgical ligation rates between patients using two different indomethacin administration protocols. This is a retrospective comparison analysis of 72 neonates, who received one of two indomethacin administration protocols. Our previous protocol suggested an initial dose of 0·2 mg/kg followed by two 0·1 mg/kg, with doses infused over 4 h and a 24-h dosing interval. A new potentially more useful protocol using the same mg/kg dose regimen but with doses infused over 30 min and a 12-h dosing interval, was evaluated. Each neonate was allowed three courses of treatment before surgical ligation was performed for persistent PDA. There were no statistically significant differences between the two protocol groups when comparing percentages of neonates with gestational age≤28 weeks, birth weight≤1000 g, male gender or receiving indomethacin for the indication of PDA prophylaxis vs. treatment. There was a trend towards a higher PDA closure rate and subsequently a lower PDA ligation rate in the new protocol when compared with the previous protocol. In this small population of premature neonates, there was a trend, but no significant difference, towards increasing PDA closure and lower surgical ligation rates in neonates given indomethacin with more frequent dosing and shorter infusion time. A well-powered randomized controlled trial is now needed. Copyright © 2010 The Authors. JCPT © 2010 Blackwell Publishing Ltd.

High-Dose Infusional Gemcitabine Combined with Busulfan and Melphalan with Autologous Stem-Cell Transplant in Patients with Refractory Lymphoid Malignancies

PubMed Central

Nieto, Y; Thall, P; Valdez, B; Andersson, B; Popat, U; Anderlini, P; Shpall, EJ; Bassett, R; Alousi, A; Hosing, C; Kebriaei, P; Qazilbash, M; Gulbis, A; Chancoco, C; Bashir, Q; Ciurea, S; Khouri, I; Parmar, S; Shah, N; Worth, L; Rondon, G; Champlin, R; Jones, RB

2014-01-01

We developed a new high-dose combination of infusional gemcitabine with busulfan/melphalan for lymphoid tumors. Gemcitabine dose was escalated by extending infusions at a fixed rate of 10 mg/m2/min in sequential cohorts, in daily, 3-dose or 2-dose schedules. Each dose immediately preceded busulfan (adjusted targeting AUC 4,000 μM.min−1/day × 4 days) or melphalan (60 mg/m2/day × 2 days). We enrolled 133 patients (80 Hodgkin’s lymphoma (HL), 46 non-Hodgkin’s lymphoma (NHL), 7 myeloma), median 3 prior regimens; primary refractory disease in 63% HL/45% NHL and PET-positive tumors at transplant in 50% patients. Two patients died from early posttransplant infections. The major toxicity was mucositis. The daily and 3-dose schedules caused substantial cutaneous toxicity. In contrast, the 2-dose schedule was better tolerated, which allowed us to extend the infusions from 15 to 270 minutes. Pretransplant values of C-reactive protein, b-type natriuretic peptide, ferritin or haptoglobin did not correlate with toxicity. Overall response and complete response rates were 87%/62% (HL), 100%/69% (B-LCL), 66%/66% (T-NHL), and 71%/57% (myeloma). At median follow-up of 24 months (3–63), the event-free/overall survival rates are 54%/72% (HL), 60%/89% (B-LCL), 70%/70% (T-NHL) and 43%/43% (myeloma). In conclusion, gemcitabine/busulfan/melphalan is a feasible regimen with substantial activity against a range of lymphoid malignancies. This regimen merits further evaluation in phase II and III trials. PMID:22643322

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

MacFarlane, Michael; Battista, Jerry; Chen, Jeff

Purpose: To develop a radiotherapy dose tracking and plan evaluation technique using cone-beam computed tomography (CBCT) images. Methods: We developed a patient-specific method of calibrating CBCT image sets for dose calculation. The planning CT was first registered with the CBCT using deformable image registration (DIR). A scatter plot was generated between the CT numbers of the planning CT and CBCT for each slice. The CBCT calibration curve was obtained by least-square fitting of the data, and applied to each CBCT slice. The calibrated CBCT was then merged with original planning CT to extend the small field of view of CBCT.more » Finally, the treatment plan was copied to the merged CT for dose tracking and plan evaluation. The proposed patient-specific calibration method was also compared to two methods proposed in literature. To evaluate the accuracy of each technique, 15 head-and-neck patients requiring plan adaptation were arbitrarily selected from our institution. The original plan was calculated on each method’s data set, including a second planning CT acquired within 48 hours of the CBCT (serving as gold standard). Clinically relevant dose metrics and 3D gamma analysis of dose distributions were compared between the different techniques. Results: Compared to the gold standard of using planning CTs, the patient-specific CBCT calibration method was shown to provide promising results with gamma pass rates above 95% and average dose metric agreement within 2.5%. Conclusions: The patient-specific CBCT calibration method could potentially be used for on-line dose tracking and plan evaluation, without requiring a re-planning CT session.« less

Thalidomide treatment in cutaneous lesions of systemic lupus erythematosus: a multicenter study in China.

PubMed

Wang, Dandan; Chen, Haifeng; Wang, Shiying; Zou, Yaohong; Li, Jing; Pan, Jieping; Wang, Xiangdang; Ren, Tianli; Zhang, Yu; Chen, Zhiwei; Feng, Xuebing; Sun, Lingyun

2016-06-01

Thalidomide is effective for treating severe cutaneous lupus patients. The aim of this study was to observe the optimum effective and maintenance doses of thalidomide to maximize clinical benefit and minimize side effects for patients with cutaneous lupus in China. Sixty-nine patients with lupus rash from eight hospitals in China were enrolled and treated with different doses of thalidomide. We started the dose of thalidomide at 25 mg daily and gradually increased administration dose once a week until erythema was markedly improved. The effective and maintenance doses were documented. The size of skin lesions was noted once a week. Systemic lupus erythematosus disease activity index (SLEDAI) score, levels of erythrocyte sedimentation rate (ESR), and serum TNF-α were measured before and after treatment. The remission rates were evaluated weekly until 8 weeks. Sixty-eight percent of patients showed an effective dose of 50 mg daily; another 13, 10, and 9 % of patients had an effective dose of 100, 75, and 25 mg daily, respectively. The maintenance dose was 50 mg daily for 71 % of the patients, and 100, 75, and 25 mg daily for 9, 14, and 6 % of the patients. SLEDAI score and serum ESR levels significantly decreased 4 weeks after thalidomide treatment. At the end of the fourth week, the rates of complete remission, partial remission, and no response were 56 % (n = 39), 41 % (n = 28), and 3 % (n = 2). At the eighth week, the rate of total remission rose up to 100 %. The most common side effects were drowsiness and constipation. No peripheral neuropathy was observed in these patients. Thalidomide at a dose of 50 mg daily may offer a better benefit to risk ratio in the treatment of Chinese cutaneous lupus patients.

SU-F-T-273: Using a Diode Array to Explore the Weakness of TPS DoseCalculation Algorithm for VMAT and Sliding Window Techniques

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

Park, J; Lu, B; Yan, G

Purpose: To identify the weakness of dose calculation algorithm in a treatment planning system for volumetric modulated arc therapy (VMAT) and sliding window (SW) techniques using a two-dimensional diode array. Methods: The VMAT quality assurance(QA) was implemented with a diode array using multiple partial arcs that divided from a VMAT plan; each partial arc has the same segments and the original monitor units. Arc angles were less than ± 30°. Multiple arcs delivered through consecutive and repetitive gantry operating clockwise and counterclockwise. The source-toaxis distance setup with the effective depths of 10 and 20 cm were used for a diodemore » array. To figure out dose errors caused in delivery of VMAT fields, the numerous fields having the same segments with the VMAT field irradiated using different delivery techniques of static and step-and-shoot. The dose distributions of the SW technique were evaluated by creating split fields having fine moving steps of multi-leaf collimator leaves. Calculated doses using the adaptive convolution algorithm were analyzed with measured ones with distance-to-agreement and dose difference of 3 mm and 3%.. Results: While the beam delivery through static and step-and-shoot techniques showed the passing rate of 97 ± 2%, partial arc delivery of the VMAT fields brought out passing rate of 85%. However, when leaf motion was restricted less than 4.6 mm/°, passing rate was improved up to 95 ± 2%. Similar passing rate were obtained for both 10 and 20 cm effective depth setup. The calculated doses using the SW technique showed the dose difference over 7% at the final arrival point of moving leaves. Conclusion: Error components in dynamic delivery of modulated beams were distinguished by using the suggested QA method. This partial arc method can be used for routine VMAT QA. Improved SW calculation algorithm is required to provide accurate estimated doses.« less

Bruton Tyrosine Kinase Inhibitor Ibrutinib (PCI-32765) Has Significant Activity in Patients With Relapsed/Refractory B-Cell Malignancies

PubMed Central

Buggy, Joseph J.; Sharman, Jeff P.; Smith, Sonali M.; Boyd, Thomas E.; Grant, Barbara; Kolibaba, Kathryn S.; Furman, Richard R.; Rodriguez, Sara; Chang, Betty Y.; Sukbuntherng, Juthamas; Izumi, Raquel; Hamdy, Ahmed; Hedrick, Eric; Fowler, Nathan H.

2013-01-01

Purpose Survival and progression of mature B-cell malignancies depend on signals from the B-cell antigen receptor, and Bruton tyrosine kinase (BTK) is a critical signaling kinase in this pathway. We evaluated ibrutinib (PCI-32765), a small-molecule irreversible inhibitor of BTK, in patients with B-cell malignancies. Patients and Methods Patients with relapsed or refractory B-cell lymphoma and chronic lymphocytic leukemia received escalating oral doses of ibrutinib. Two schedules were evaluated: one, 28 days on, 7 days off; and two, once-daily continuous dosing. Occupancy of BTK by ibrutinib in peripheral blood was monitored using a fluorescent affinity probe. Dose escalation proceeded until either the maximum-tolerated dose (MTD) was achieved or, in the absence of MTD, until three dose levels above full BTK occupancy by ibrutinib. Response was evaluated every two cycles. Results Fifty-six patients with a variety of B-cell malignancies were treated over seven cohorts. Most adverse events were grade 1 and 2 in severity and self-limited. Dose-limiting events were not observed, even with prolonged dosing. Full occupancy of the BTK active site occurred at 2.5 mg/kg per day, and dose escalation continued to 12.5 mg/kg per day without reaching MTD. Pharmacokinetic data indicated rapid absorption and elimination, yet BTK occupancy was maintained for at least 24 hours, consistent with the irreversible mechanism. Objective response rate in 50 evaluable patients was 60%, including complete response of 16%. Median progression-free survival in all patients was 13.6 months. Conclusion Ibrutinib, a novel BTK-targeting inhibitor, is well tolerated, with substantial activity across B-cell histologies. PMID:23045577

GDF-15 gene expression alterations in human lymphoblastoid cells and peripheral blood lymphocytes following exposure to ionizing radiation

PubMed Central

Li, Shuang; Zhang, Qing-Zhao; Zhang, De-Qin; Feng, Jiang-Bin; Luo, Qun; Lu, Xue; Wang, Xin-Ru; Li, Kun-Peng; Chen, De-Qing; Mu, Xiao-Feng; Gao, Ling; Liu, Qing-Jie

2017-01-01

The identification of rapid, sensitive and high-throughput biomarkers is imperative in order to identify individuals harmed by radiation accidents, and accurately evaluate the absorbed doses of radiation. DNA microarrays have previously been used to evaluate the alterations in growth/differentiation factor 15 (GDF15) gene expression in AHH-1 human lymphoblastoid cells, following exposure to γ-rays. The present study aimed to characterize the relationship between the dose of ionizing radiation and the produced effects in GDF-15 gene expression in AHH-1 cells and human peripheral blood lymphocytes (HPBLs). GDF-15 mRNA and protein expression levels following exposure to γ-rays and neutron radiation were assessed by reverse transcription-quantitative polymerase chain reaction and western blot analysis in AHH-1 cells. In addition, alterations in GDF-15 gene expression in HPBLs following ex vivo irradiation were evaluated. The present results demonstrated that GDF-15 mRNA and protein expression levels in AHH-1 cells were significantly upregulated following exposure to γ-ray doses ranging between 1 and 10 Gy, regardless of the dose rate. A total of 48 h following exposure to neutron radiation, a dose-response relationship was identified in AHH-1 cells at γ-ray doses between 0.4 and 1.6 Gy. GDF-15 mRNA levels in HPBLs were significantly upregulated following exposure to γ-ray doses between 1 and 8 Gy, within 4–48 h following irradiation. These results suggested that significant time- and dose-dependent alterations in GDF-15 mRNA and protein expression occur in AHH-1 cells and HPBLs in the early phases following exposure to ionizing radiation. In conclusion, alterations in GDF-15 gene expression may have potential as a biomarker to evaluate radiation exposure. PMID:28440431

Bruton tyrosine kinase inhibitor ibrutinib (PCI-32765) has significant activity in patients with relapsed/refractory B-cell malignancies.

PubMed

Advani, Ranjana H; Buggy, Joseph J; Sharman, Jeff P; Smith, Sonali M; Boyd, Thomas E; Grant, Barbara; Kolibaba, Kathryn S; Furman, Richard R; Rodriguez, Sara; Chang, Betty Y; Sukbuntherng, Juthamas; Izumi, Raquel; Hamdy, Ahmed; Hedrick, Eric; Fowler, Nathan H

2013-01-01

Survival and progression of mature B-cell malignancies depend on signals from the B-cell antigen receptor, and Bruton tyrosine kinase (BTK) is a critical signaling kinase in this pathway. We evaluated ibrutinib (PCI-32765), a small-molecule irreversible inhibitor of BTK, in patients with B-cell malignancies. Patients with relapsed or refractory B-cell lymphoma and chronic lymphocytic leukemia received escalating oral doses of ibrutinib. Two schedules were evaluated: one, 28 days on, 7 days off; and two, once-daily continuous dosing. Occupancy of BTK by ibrutinib in peripheral blood was monitored using a fluorescent affinity probe. Dose escalation proceeded until either the maximum-tolerated dose (MTD) was achieved or, in the absence of MTD, until three dose levels above full BTK occupancy by ibrutinib. Response was evaluated every two cycles. Fifty-six patients with a variety of B-cell malignancies were treated over seven cohorts. Most adverse events were grade 1 and 2 in severity and self-limited. Dose-limiting events were not observed, even with prolonged dosing. Full occupancy of the BTK active site occurred at 2.5 mg/kg per day, and dose escalation continued to 12.5 mg/kg per day without reaching MTD. Pharmacokinetic data indicated rapid absorption and elimination, yet BTK occupancy was maintained for at least 24 hours, consistent with the irreversible mechanism. Objective response rate in 50 evaluable patients was 60%, including complete response of 16%. Median progression-free survival in all patients was 13.6 months. Ibrutinib, a novel BTK-targeting inhibitor, is well tolerated, with substantial activity across B-cell histologies.

Characteristics of flattening filter free beams at low monitor unit settings.

PubMed

Akino, Yuichi; Ota, Seiichi; Inoue, Shinichi; Mizuno, Hirokazu; Sumida, Iori; Yoshioka, Yasuo; Isohashi, Fumiaki; Ogawa, Kazuhiko

2013-11-01

Newer linear accelerators (linacs) have been equipped to deliver flattening filter free (FFF) beams. When FFF beams are used for step-and-shoot intensity-modulated radiotherapy (IMRT), the stability of delivery of small numbers of monitor units (MU) is important. The authors developed automatic measurement techniques to evaluate the stability of the dose profile, dose linearity, and consistency. Here, the authors report the performance of the Artiste™ accelerator (Siemens, Erlangen, Germany) in delivering low-MU FFF beams. A 6 MV flattened beam (6X) with 300 MU/min dose rate and FFF beams of 7 (7XU) and 11 MV (11XU), each with a 500 MU/min dose rate, were measured at 1, 2, 3, 5, 8, 10, and 20 MU settings. For the 2000 MU/min dose rate, the 7 (7XUH) and 11 MV (11XUH) beams were set at 10, 15, 20, 25, and 30 MU because of the limits of the minimum MU settings. Beams with 20 × 20 and 10 × 10 cm(2) field sizes were alternately measured ten times in intensity modulated (IM) mode, with which Siemens linacs regulate beam delivery for step-and-shoot IMRT. The in- and crossplane beam profiles were measured using a Profiler™ Model 1170 (Sun Nuclear Corporation, Melbourne, FL) in multiframe mode. The frames of 20 × 20 cm(2) beams were identified at the off-axis profile. The 6X beam profile was normalized at the central axis. The 7 and 11 MV FFF beam profiles were rescaled to set the dose at the central axis at 145% and 170%, respectively. Point doses were also measured using a Farmer-type ionization chamber and water-equivalent solid phantom to evaluate the linearity and consistency of low-MU beam delivery. The values displayed on the electrometer were recognized with a USB-type camera and read with open-source optical character recognition software. The symmetry measurements of the 6X, 7XU, and 11XU beam profiles were better than 2% for beams ≥ 2 MU and improved with increasing MU. The variations in flatness of FFF beams ≥ 2 MU were ± 5%. The standard deviation of the symmetry and flatness also decreased with increasing MU. The linearity of the 6X beam was ± 1% and ± 2% for the beams of ≥ 5 and ≥ 3 MU, respectively. The 7XU and 11XU beams of ≥ 2 MU showed linearity with ± 2% except the 7XU beam of 8 MU (+2.9%). The profiles of the FFF beams with 2000 and 500 MU/min dose rate were similar. The characteristics of low-MU beams delivered in IM mode were evaluated using an automatic measurement system developed in this study. The authors demonstrated that the profiles of FFF beams of the Artiste™ linac were highly stable, even at low MU. The linearity of dose output was also stable for beams ≥ 2 MU.

Evaluation of three presets for four-dimensional cone beam CT in lung radiotherapy verification by visual grading analysis.

PubMed

Kember, Sally A; Hansen, Vibeke N; Fast, Martin F; Nill, Simeon; McDonald, Fiona; Ahmed, Merina; Thomas, Karen; McNair, Helen A

2016-07-01

To evaluate three image acquisition presets for four-dimensional cone beam CT (CBCT) to identify an optimal preset for lung tumour image quality while minimizing dose and acquisition time. Nine patients undergoing radical conventionally fractionated radiotherapy for lung cancer had verification CBCTs acquired using three presets: Preset 1 on Day 1 (11 mGy dose, 240 s acquisition time), Preset 2 on Day 2 (9 mGy dose, 133 s acquisition time) and Preset 3 on Day 3 (9 mGy dose, 67 s acquisition time). The clarity of the tumour and other thoracic structures, and the acceptability of the match, were retrospectively graded by visual grading analysis (VGA). Logistic regression was used to identify the most appropriate preset and any factors that might influence the result. Presets 1 and 2 met a clinical requirement of 75% of structures to be rated "Clear" or above and 75% of matches to be rated "Acceptable" or above. Clarity is significantly affected by preset, patient, observer and structure. Match acceptability is significantly affected by preset. The application of VGA in this initial study enabled a provisional selection of an optimal preset (Preset 2) to be made. This was the first application of VGA to the investigation of presets for CBCT.

A Prospective Randomized Trial of Apixaban Dosing During Atrial Fibrillation Ablation: The AEIOU Trial.

PubMed

Reynolds, Matthew R; Allison, J Scott; Natale, Andrea; Weisberg, Ian L; Ellenbogen, Kenneth A; Richards, Mark; Hsieh, Wen-Hua; Sutherland, Julie; Cannon, Christopher P

2018-05-01

This study sought to determine whether uninterrupted apixaban would have similar rates of bleeding and thromboembolic events as does minimally interrupted apixaban at the time of atrial fibrillation (AF) ablation and to compare those results with rates in historical patients treated with uninterrupted warfarin. The safety, efficacy, and optimal dosing regimen for apixaban at the time of AF ablation are uncertain. This prospective, multicenter clinical trial enrolled 306 patients undergoing catheter ablation for nonvalvular AF and randomized 300 to uninterrupted versus minimally interrupted (holding 1 dose) periprocedural apixaban. A retrospective cohort of patients treated with uninterrupted warfarin at the same centers was matched to the apixaban-treated subjects for comparison. Endpoints included clinically significant bleeding, major bleeding, and nonhemorrhagic stroke or systemic embolism (SE) from the time of ablation through 30 days. There were no stroke or SE events. Clinically significant bleeding occurred in 11.3% of 150 evaluable patients on uninterrupted apixaban and 9.7% of 145 evaluable patients on interrupted apixaban (risk difference: 1.7% [95% confidence interval: -5.5% to 8.8%]; p = NS). Rates of major bleeding were 1.3% with uninterrupted apixaban, and 2.1% with interrupted (risk difference: -0.7%; p = NS). The rates of clinically significant and major bleeding were similar for all apixaban patients combined (10.5% and 1.7%), compared with the matched warfarin group (9.8% and 1.4%). Both uninterrupted and minimally interrupted apixaban at the time of AF ablation were associated with a very low rate of thromboembolic events, and rates of both major (<2%) and clinically significant bleeding were similar to uninterrupted warfarin. (Apixaban Evaluation of Interrupted Or Uninterrupted Anticoagulation for Ablation of Atrial Fibrillation [AEIOU]; NCT02608099). Copyright © 2018 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

Outcomes of Direct Vision Internal Urethrotomy for Bulbar Urethral Strictures: Technique Modification with High Dose Triamcinolone Injection.

PubMed

Modh, Rishi; Cai, Peter Y; Sheffield, Alyssa; Yeung, Lawrence L

2015-01-01

Objective. To evaluate the recurrence rate of bulbar urethral strictures managed with cold knife direct vision internal urethrotomy and high dose corticosteroid injection. Methods. 28 patients with bulbar urethral strictures underwent direct vision internal urethrotomy with high dose triamcinolone injection into the periurethral tissue and were followed up for recurrence. Results. Our cohort had a mean age of 60 years and average stricture length of 1.85 cm, and 71% underwent multiple previous urethral stricture procedures with an average of 5.7 procedures each. Our technique modification of high dose corticosteroid injection had a recurrence rate of 29% at a mean follow-up of 20 months with a low rate of urinary tract infections. In patients who failed treatment, mean time to stricture recurrence was 7 months. Patients who were successfully treated had significantly better International Prostate Symptom Scores at 6, 9, and 12 months. There was no significant difference in maximum flow velocity on Uroflowmetry at last follow-up but there was significant difference in length of follow-up (p = 0.02). Conclusions. High dose corticosteroid injection at the time of direct vision internal urethrotomy is a safe and effective procedure to delay anatomical and symptomatic recurrence of bulbar urethral strictures, particularly in those who are poor candidates for urethroplasty.

Case Example of Dose Optimization Using Data From Bortezomib Dose-Finding Clinical Trials

PubMed Central

Backenroth, Daniel; Cheung, Ying Kuen Ken; Hershman, Dawn L.; Vulih, Diana; Anderson, Barry; Ivy, Percy; Minasian, Lori

2016-01-01

Purpose The current dose-finding methodology for estimating the maximum tolerated dose of investigational anticancer agents is based on the cytotoxic chemotherapy paradigm. Molecularly targeted agents (MTAs) have different toxicity profiles, which may lead to more long-lasting mild or moderate toxicities as well as to late-onset and cumulative toxicities. Several approved MTAs have been poorly tolerated during long-term administration, leading to postmarketing dose optimization studies to re-evaluate the optimal treatment dose. Using data from completed bortezomib dose-finding trials, we explore its toxicity profile, optimize its dose, and examine the appropriateness of current designs for identifying an optimal dose. Patients and Methods We classified the toxicities captured from 481 patients in 14 bortezomib dose-finding studies conducted through the National Cancer Institute Cancer Therapy Evaluation Program, computed the incidence of late-onset toxicities, and compared the incidence of dose-limiting toxicities (DLTs) among groups of patients receiving different doses of bortezomib. Results A total of 13,008 toxicities were captured: 46% of patients’ first DLTs and 88% of dose reductions or discontinuations of treatment because of toxicity were observed after the first cycle. Moreover, for the approved dose of 1.3 mg/m2, the estimated cumulative incidence of DLT was > 50%, and the estimated cumulative incidence of dose reduction or treatment discontinuation because of toxicity was nearly 40%. Conclusions When considering the entire course of treatment, the approved bortezomib dose exceeds the conventional ceiling DLT rate of 20% to 33%. Retrospective analysis of trial data provides an opportunity for dose optimization of MTAs. Future dose-finding studies of MTAs should take into account late-onset toxicities to ensure that a tolerable dose is identified for future efficacy and comparative trials. PMID:26926682

Case Example of Dose Optimization Using Data From Bortezomib Dose-Finding Clinical Trials.

PubMed

Lee, Shing M; Backenroth, Daniel; Cheung, Ying Kuen Ken; Hershman, Dawn L; Vulih, Diana; Anderson, Barry; Ivy, Percy; Minasian, Lori

2016-04-20

The current dose-finding methodology for estimating the maximum tolerated dose of investigational anticancer agents is based on the cytotoxic chemotherapy paradigm. Molecularly targeted agents (MTAs) have different toxicity profiles, which may lead to more long-lasting mild or moderate toxicities as well as to late-onset and cumulative toxicities. Several approved MTAs have been poorly tolerated during long-term administration, leading to postmarketing dose optimization studies to re-evaluate the optimal treatment dose. Using data from completed bortezomib dose-finding trials, we explore its toxicity profile, optimize its dose, and examine the appropriateness of current designs for identifying an optimal dose. We classified the toxicities captured from 481 patients in 14 bortezomib dose-finding studies conducted through the National Cancer Institute Cancer Therapy Evaluation Program, computed the incidence of late-onset toxicities, and compared the incidence of dose-limiting toxicities (DLTs) among groups of patients receiving different doses of bortezomib. A total of 13,008 toxicities were captured: 46% of patients' first DLTs and 88% of dose reductions or discontinuations of treatment because of toxicity were observed after the first cycle. Moreover, for the approved dose of 1.3 mg/m(2), the estimated cumulative incidence of DLT was > 50%, and the estimated cumulative incidence of dose reduction or treatment discontinuation because of toxicity was nearly 40%. When considering the entire course of treatment, the approved bortezomib dose exceeds the conventional ceiling DLT rate of 20% to 33%. Retrospective analysis of trial data provides an opportunity for dose optimization of MTAs. Future dose-finding studies of MTAs should take into account late-onset toxicities to ensure that a tolerable dose is identified for future efficacy and comparative trials. © 2016 by American Society of Clinical Oncology.

A Quality Assurance Method that Utilizes 3D Dosimetry and Facilitates Clinical Interpretation

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

Oldham, Mark, E-mail: mark.oldham@duke.edu; Thomas, Andrew; O'Daniel, Jennifer

2012-10-01

Purpose: To demonstrate a new three-dimensional (3D) quality assurance (QA) method that provides comprehensive dosimetry verification and facilitates evaluation of the clinical significance of QA data acquired in a phantom. Also to apply the method to investigate the dosimetric efficacy of base-of-skull (BOS) intensity-modulated radiotherapy (IMRT) treatment. Methods and Materials: Two types of IMRT QA verification plans were created for 6 patients who received BOS IMRT. The first plan enabled conventional 2D planar IMRT QA using the Varian portal dosimetry system. The second plan enabled 3D verification using an anthropomorphic head phantom. In the latter, the 3D dose distribution wasmore » measured using the DLOS/Presage dosimetry system (DLOS = Duke Large-field-of-view Optical-CT System, Presage Heuris Pharma, Skillman, NJ), which yielded isotropic 2-mm data throughout the treated volume. In a novel step, measured 3D dose distributions were transformed back to the patient's CT to enable calculation of dose-volume histograms (DVH) and dose overlays. Measured and planned patient DVHs were compared to investigate clinical significance. Results: Close agreement between measured and calculated dose distributions was observed for all 6 cases. For gamma criteria of 3%, 2 mm, the mean passing rate for portal dosimetry was 96.8% (range, 92.0%-98.9%), compared to 94.9% (range, 90.1%-98.9%) for 3D. There was no clear correlation between 2D and 3D passing rates. Planned and measured dose distributions were evaluated on the patient's anatomy, using DVH and dose overlays. Minor deviations were detected, and the clinical significance of these are presented and discussed. Conclusions: Two advantages accrue to the methods presented here. First, treatment accuracy is evaluated throughout the whole treated volume, yielding comprehensive verification. Second, the clinical significance of any deviations can be assessed through the generation of DVH curves and dose overlays on the patient's anatomy. The latter step represents an important development that advances the clinical relevance of complex treatment QA.« less

Artemether-lumefantrine dosing for malaria treatment in young children and pregnant women: A pharmacokinetic-pharmacodynamic meta-analysis.

PubMed

Kloprogge, Frank; Workman, Lesley; Borrmann, Steffen; Tékété, Mamadou; Lefèvre, Gilbert; Hamed, Kamal; Piola, Patrice; Ursing, Johan; Kofoed, Poul Erik; Mårtensson, Andreas; Ngasala, Billy; Björkman, Anders; Ashton, Michael; Friberg Hietala, Sofia; Aweeka, Francesca; Parikh, Sunil; Mwai, Leah; Davis, Timothy M E; Karunajeewa, Harin; Salman, Sam; Checchi, Francesco; Fogg, Carole; Newton, Paul N; Mayxay, Mayfong; Deloron, Philippe; Faucher, Jean François; Nosten, François; Ashley, Elizabeth A; McGready, Rose; van Vugt, Michele; Proux, Stephane; Price, Ric N; Karbwang, Juntra; Ezzet, Farkad; Bakshi, Rajesh; Stepniewska, Kasia; White, Nicholas J; Guerin, Philippe J; Barnes, Karen I; Tarning, Joel

2018-06-01

The fixed dose combination of artemether-lumefantrine (AL) is the most widely used treatment for uncomplicated Plasmodium falciparum malaria. Relatively lower cure rates and lumefantrine levels have been reported in young children and in pregnant women during their second and third trimester. The aim of this study was to investigate the pharmacokinetic and pharmacodynamic properties of lumefantrine and the pharmacokinetic properties of its metabolite, desbutyl-lumefantrine, in order to inform optimal dosing regimens in all patient populations. A search in PubMed, Embase, ClinicalTrials.gov, Google Scholar, conference proceedings, and the WorldWide Antimalarial Resistance Network (WWARN) pharmacology database identified 31 relevant clinical studies published between 1 January 1990 and 31 December 2012, with 4,546 patients in whom lumefantrine concentrations were measured. Under the auspices of WWARN, relevant individual concentration-time data, clinical covariates, and outcome data from 4,122 patients were made available and pooled for the meta-analysis. The developed lumefantrine population pharmacokinetic model was used for dose optimisation through in silico simulations. Venous plasma lumefantrine concentrations 7 days after starting standard AL treatment were 24.2% and 13.4% lower in children weighing <15 kg and 15-25 kg, respectively, and 20.2% lower in pregnant women compared with non-pregnant adults. Lumefantrine exposure decreased with increasing pre-treatment parasitaemia, and the dose limitation on absorption of lumefantrine was substantial. Simulations using the lumefantrine pharmacokinetic model suggest that, in young children and pregnant women beyond the first trimester, lengthening the dose regimen (twice daily for 5 days) and, to a lesser extent, intensifying the frequency of dosing (3 times daily for 3 days) would be more efficacious than using higher individual doses in the current standard treatment regimen (twice daily for 3 days). The model was developed using venous plasma data from patients receiving intact tablets with fat, and evaluations of alternative dosing regimens were consequently only representative for venous plasma after administration of intact tablets with fat. The absence of artemether-dihydroartemisinin data limited the prediction of parasite killing rates and recrudescent infections. Thus, the suggested optimised dosing schedule was based on the pharmacokinetic endpoint of lumefantrine plasma exposure at day 7. Our findings suggest that revised AL dosing regimens for young children and pregnant women would improve drug exposure but would require longer or more complex schedules. These dosing regimens should be evaluated in prospective clinical studies to determine whether they would improve cure rates, demonstrate adequate safety, and thereby prolong the useful therapeutic life of this valuable antimalarial treatment.

Low dosing of gonadotropins in in vitro fertilization cycles for women with poor ovarian reserve: systematic review and meta-analysis.

PubMed

Youssef, Mohamed Abdel-Fattah; van Wely, Madelon; Mochtar, Monique; Fouda, Usama Mohamed; Eldaly, Ashraf; El Abidin, Eman Zein; Elhalwagy, Ahmed; Mageed Abdallah, Ahmed Abdel; Zaki, Sherif Sameh; Abdel Ghafar, Mohamed Sayed; Mohesen, Mohamed Nagi; van der Veen, Fulco

2018-02-01

To evaluate the effectiveness of low doses of gonadotropins and gonadotropins combined with oral compounds compared with high doses of gonadotropins in ovarian stimulation regimens in terms of ongoing pregnancy per fresh IVF attempt in women with poor ovarian reserve undergoing IVF/intracytoplasmic sperm injection (ICSI) treatment. A systematic review and meta-analysis of randomized controlled studies that evaluate the effectiveness of low dosing of gonadotropins alone or combined with oral compounds compared with high doses of gonadotropins in women with poor ovarian reserve undergoing IVF/ICSI treatment. Not applicable. Subfertile women with poor ovarian reserve undergoing IVF/ICSI treatment. We searched the PubMed, EMBASE, Web of Science, the Cochrane Library, and the Clinical Trials Registry using medical subject headings and free text terms up to June 2016, without language or year restrictions. We included randomized controlled studies (RCTs) enrolling subfertile women with poor ovarian reserve undergoing IVF/ICSI treatment and comparing low doses of gonadotropins and gonadotropins combined with oral compounds versus high doses of gonadotropins. We assessed the risk of bias using the criteria recommended by the Cochrane Collaboration. We pooled the results by meta-analysis using the fixed and random effects model. The primary outcome was ongoing pregnancy rate (PR) per woman randomized. We retrieved 787 records. Fourteen RCTs (N = 2,104 women) were included in the analysis. Five studies (N = 717 women) compared low doses of gonadotropins versus high doses of gonadotropins. There was no evidence of a difference in ongoing PR (2 RCTs: risk rate 0.98, 95% confidence interval 0.62-1.57, I 2 = 0). Nine studies (N = 1,387 women) compared ovarian stimulation using gonadotropins combined with the oral compounds letrozole (n = 6) or clomiphene citrate (CC) (n = 3) versus high doses of gonadotropins. There was no evidence of a difference in ongoing PR (3 RCTs: risk rate 0.90, 95% confidence interval 0.63-1.27, I 2 = 0). We found no evidence of a difference in pregnancy outcomes between low doses of gonadotropins and gonadotropins combined with oral compounds compared with high doses of gonadotropins in ovarian stimulation regimens. Whether low doses of gonadotropins or gonadotropins combined with oral compounds is to be preferred is unknown, as they have never been compared head to head. A health economic analysis to test the hypothesis that an ovarian stimulation with low dosing is more cost-effective than high doses of gonadotropins is needed. CRD42016041301. Copyright © 2017 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.

Radiation hardness study of semi-insulating GaAs detectors against 5 MeV electrons

NASA Astrophysics Data System (ADS)

Šagátová, A.; Zaťko, B.; Nečas, V.; Sedlačková, K.; Boháček, P.; Fülöp, M.; Pavlovič, M.

2018-01-01

A radiation hardness study of Semi-Insulating (SI) GaAs detectors against 5 MeV electrons is described in this paper. The influence of two parameters, the accumulative absorbed dose (from 1 to 200 kGy) and the applied dose rate (20, 40 or 80 kGy/h), on detector spectrometric properties were studied. The accumulative dose has influenced all evaluated spectrometric properties and also negatively affected the detector CCE (Charge Collection Efficiency). We have observed its systematic reduction from an initial 79% before irradiation down to about 51% at maximum dose of 200 kGy. Relative energy resolution was also influenced by electron irradiation. Its degradation was obvious in the range of doses from 24 up to a maximum dose of 200 kGy, where an increase from 19% up to 31% at 200 V reverse voltage was noticed. On the other hand, a global increase of detection efficiency with accumulative absorbed dose was observed for all samples. Concerning the actual detector degradation we can assume that the tested SI GaAs detectors will be able to operate up to a dose of 300 kGy at least, when irradiated by 5 MeV electrons. The second investigated parameter of irradiation, the dose rate of chosen ranges, did not greatly alter the spectrometric properties of studied detectors.

SU-E-T-421: Feasibility Study of Volumetric Modulated Arc Therapy with Constant Dose Rate for Endometrial Cancer

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

Yang, R; Wang, J

2014-06-01

Purpose: To investigate the feasibility, efficiency, and delivery accuracy of volumetric modulated arc therapy with constant dose rate (VMAT-CDR) for whole-pelvic radiotherapy (WPRT) of endometrial cancer. Methods: The nine-Field intensity-modulated radiotherapy (IMRT), VMAT with variable dose-rate (VMAT-VDR), and VMAT-CDR plans were created for 9 patients with endometrial cancer undergoing WPRT. The dose distribution of planning target volume (PTV), organs at risk (OARs), and normal tissue (NT) were compared. The monitor units (MUs) and treatment delivery time were also evaluated. For each VMAT-CDR plan, a dry Run was performed to assess the dosimetric accuracy with MatriXX from IBA. Results: Compared withmore » IMRT, the VMAT-CDR plans delivered a slightly greater V20 of the bowel, bladder, pelvis bone, and NT, but significantly decreased the dose to the high-dose region of the rectum and pelvis bone. The MUs Decreased from 1105 with IMRT to 628 with VMAT-CDR. The delivery time also decreased from 9.5 to 3.2 minutes. The average gamma pass rate was 95.6% at the 3%/3 mm criteria with MatriXX pretreatment verification for 9 patients. Conclusion: VMAT-CDR can achieve comparable plan quality with significant shorter delivery time and smaller number of MUs compared with IMRT for patients with endometrial cancer undergoing WPRT. It can be accurately delivered and be an alternative to IMRT on the linear accelerator without VDR capability. This work is supported by the grant project, National Natural; Science Foundation of China (No. 81071237)« less

Efficacy of tofacitinib in patients with rheumatoid arthritis stratified by background methotrexate dose group.

PubMed

Fleischmann, R; Mease, P J; Schwartzman, S; Hwang, L-J; Soma, K; Connell, C A; Takiya, L; Bananis, E

2017-01-01

Tofacitinib is an oral Janus kinase inhibitor for the treatment of rheumatoid arthritis (RA). This post hoc analysis investigated the effect of methotrexate (MTX) dose on the efficacy of tofacitinib in patients with RA. ORAL Scan (NCT00847613) was a 2-year, randomized, Phase 3 trial evaluating tofacitinib in MTX-inadequate responder (IR) patients with RA. Patients received tofacitinib 5 or 10 mg twice daily (BID), or placebo, with low (≤12.5 mg/week), moderate (>12.5 to <17.5 mg/week), or high (≥17.5 mg/week) stable background MTX. Efficacy endpoints (at months 3 and 6) included American College of Rheumatology (ACR) 20/50/70 response rates, and mean change from baseline in Clinical Disease Activity Index (CDAI), Disease Activity Score in 28 joints (DAS28)-4(erythrocyte sedimentation rate [ESR]), Health Assessment Questionnaire-Disability Index (HAQ-DI), and modified Total Sharp score. 797 patients were treated with tofacitinib 5 mg BID (N = 321), tofacitinib 10 mg BID (N = 316), or placebo (N = 160); 242, 333, and 222 patients received low, moderate, and high MTX doses, respectively. At months 3 and 6, ACR20/50/70 response rates were greater for both tofacitinib doses vs placebo across all MTX doses. At month 3, mean changes from baseline in CDAI and HAQ-DI were significantly greater for both tofacitinib doses vs placebo, irrespective of MTX category; improvements were maintained at month 6. Both tofacitinib doses demonstrated improvements in DAS28-4(ESR), and less structural progression vs placebo, across MTX doses at month 6. Tofacitinib plus MTX showed greater clinical and radiographic efficacy than placebo in MTX-IR patients with RA, regardless of MTX dose.

In vivo thermoluminescence dosimetry dose verification of transperineal 192Ir high-dose-rate brachytherapy using CT-based planning for the treatment of prostate cancer.

PubMed

Anagnostopoulos, G; Baltas, D; Geretschlaeger, A; Martin, T; Papagiannis, P; Tselis, N; Zamboglou, N

2003-11-15

To evaluate the potential of in vivo thermoluminescence dosimetry to estimate the accuracy of dose delivery in conformal high-dose-rate brachytherapy of prostate cancer. A total of 50 LiF, TLD-100 cylindrical rods were calibrated in the dose range of interest and used as a batch for all fractions. Fourteen dosimeters for every treatment fraction were loaded in a plastic 4F catheter that was fixed in either one of the 6F needles implanted for treatment purposes or in an extra needle implanted after consulting with the patient. The 6F needles were placed either close to the urethra or in the vicinity of the median posterior wall of the prostate. Initial results are presented for 18 treatment fractions in 5 patients and compared to corresponding data calculated using the commercial treatment planning system used for the planning of the treatments based on CT images acquired postimplantation. The maximum observed mean difference between planned and delivered dose within a single treatment fraction was 8.57% +/- 2.61% (root mean square [RMS] errors from 4.03% to 9.73%). Corresponding values obtained after averaging results over all fractions of a patient were 6.88% +/- 4.93% (RMS errors from 4.82% to 7.32%). Experimental results of each fraction corresponding to the same patient point were found to agree within experimental uncertainties. Experimental results indicate that the proposed method is feasible for dose verification purposes and suggest that dose delivery in transperineal high-dose-rate brachytherapy after CT-based planning can be of acceptable accuracy.

Sci—Thur AM: YIS - 03: irtGPUMCD: a new GPU-calculated dosimetry code for {sup 177}Lu-octreotate radionuclide therapy of neuroendocrine tumors

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

Montégiani, Jean-François; Gaudin, Émilie; Després, Philippe

2014-08-15

In peptide receptor radionuclide therapy (PRRT), huge inter-patient variability in absorbed radiation doses per administered activity mandates the utilization of individualized dosimetry to evaluate therapeutic efficacy and toxicity. We created a reliable GPU-calculated dosimetry code (irtGPUMCD) and assessed {sup 177}Lu-octreotate renal dosimetry in eight patients (4 cycles of approximately 7.4 GBq). irtGPUMCD was derived from a brachytherapy dosimetry code (bGPUMCD), which was adapted to {sup 177}Lu PRRT dosimetry. Serial quantitative single-photon emission computed tomography (SPECT) images were obtained from three SPECT/CT acquisitions performed at 4, 24 and 72 hours after {sup 177}Lu-octreotate administration, and registered with non-rigid deformation of CTmore » volumes, to obtain {sup 177}Lu-octreotate 4D quantitative biodistribution. Local energy deposition from the β disintegrations was assumed. Using Monte Carlo gamma photon transportation, irtGPUMCD computed dose rate at each time point. Average kidney absorbed dose was obtained from 1-cm{sup 3} VOI dose rate samples on each cortex, subjected to a biexponential curve fit. Integration of the latter time-dose rate curve yielded the renal absorbed dose. The mean renal dose per administered activity was 0.48 ± 0.13 Gy/GBq (range: 0.30–0.71 Gy/GBq). Comparison to another PRRT dosimetry code (VRAK: Voxelized Registration and Kinetics) showed fair accordance with irtGPUMCD (11.4 ± 6.8 %, range: 3.3–26.2%). These results suggest the possibility to use the irtGPUMCD code in order to personalize administered activity in PRRT. This could allow improving clinical outcomes by maximizing per-cycle tumor doses, without exceeding the tolerable renal dose.« less

SOC-DS computer code provides tool for design evaluation of homogeneous two-material nuclear shield

NASA Technical Reports Server (NTRS)

Disney, R. K.; Ricks, L. O.

1967-01-01

SOC-DS Code /Shield Optimization Code-Direc Search/, selects a nuclear shield material of optimum volume, weight, or cost to meet the requirments of a given radiation dose rate or energy transmission constraint. It is applicable to evaluating neutron and gamma ray shields for all nuclear reactors.

The pharmacological effects of the anesthetic alfaxalone after intramuscular administration to dogs.

PubMed

Tamura, Jun; Ishizuka, Tomohito; Fukui, Sho; Oyama, Norihiko; Kawase, Kodai; Miyoshi, Kenjiro; Sano, Tadashi; Pasloske, Kirby; Yamashita, Kazuto

2015-03-01

The pharmacological effects of the anesthetic alfaxalone were evaluated after intramuscular (IM) administration to 6 healthy beagle dogs. The dogs received three IM doses each of alfaxalone at increasing dose rates of 5 mg/kg (IM5), 7.5 mg/kg (IM7.5) and 10 mg/kg (IM10) every other day. Anesthetic effect was subjectively evaluated by using an ordinal scoring system to determine the degree of neuro-depression and the quality of anesthetic induction and recovery from anesthesia. Cardiorespiratory variables were measured using noninvasive methods. Alfaxalone administered IM produced dose-dependent neuro-depression and lateral recumbency (i.e., 36 ± 28 min, 87 ± 26 min and 115 ± 29 min after the IM5, IM7.5 and IM10 treatments, respectively). The endotracheal tube was tolerated in all dogs for 46 ± 20 and 58 ± 21 min after the IM7.5 and IM10 treatments, respectively. It was not possible to place endotracheal tubes in 5 of the 6 dogs after the IM5 treatment. Most cardiorespiratory variables remained within clinically acceptable ranges, but hypoxemia was observed by pulse oximetry for 5 to 10 min in 2 dogs receiving the IM10 treatment. Dose-dependent decreases in rectal temperature, respiratory rate and arterial blood pressure also occurred. The quality of recovery was considered satisfactory in all dogs receiving each treatment; all the dog exhibited transient muscular tremors and staggering gait. In conclusion, IM alfaxalone produced a dose-dependent anesthetic effect with relatively mild cardiorespiratory depression in dogs. However, hypoxemia may occur at higher IM doses of alfaxalone.

The pharmacological effects of the anesthetic alfaxalone after intramuscular administration to dogs

PubMed Central

TAMURA, Jun; ISHIZUKA, Tomohito; FUKUI, Sho; OYAMA, Norihiko; KAWASE, Kodai; MIYOSHI, Kenjiro; SANO, Tadashi; PASLOSKE, Kirby; YAMASHITA, Kazuto

2014-01-01

The pharmacological effects of the anesthetic alfaxalone were evaluated after intramuscular (IM) administration to 6 healthy beagle dogs. The dogs received three IM doses each of alfaxalone at increasing dose rates of 5 mg/kg (IM5), 7.5 mg/kg (IM7.5) and 10 mg/kg (IM10) every other day. Anesthetic effect was subjectively evaluated by using an ordinal scoring system to determine the degree of neuro-depression and the quality of anesthetic induction and recovery from anesthesia. Cardiorespiratory variables were measured using noninvasive methods. Alfaxalone administered IM produced dose-dependent neuro-depression and lateral recumbency (i.e., 36 ± 28 min, 87 ± 26 min and 115 ± 29 min after the IM5, IM7.5 and IM10 treatments, respectively). The endotracheal tube was tolerated in all dogs for 46 ± 20 and 58 ± 21 min after the IM7.5 and IM10 treatments, respectively. It was not possible to place endotracheal tubes in 5 of the 6 dogs after the IM5 treatment. Most cardiorespiratory variables remained within clinically acceptable ranges, but hypoxemia was observed by pulse oximetry for 5 to 10 min in 2 dogs receiving the IM10 treatment. Dose-dependent decreases in rectal temperature, respiratory rate and arterial blood pressure also occurred. The quality of recovery was considered satisfactory in all dogs receiving each treatment; all the dog exhibited transient muscular tremors and staggering gait. In conclusion, IM alfaxalone produced a dose-dependent anesthetic effect with relatively mild cardiorespiratory depression in dogs. However, hypoxemia may occur at higher IM doses of alfaxalone. PMID:25428797

Treatment modifications in tumour necrosis factor-α (TNF)-based isolated limb perfusion in patients with advanced extremity soft tissue sarcomas.

PubMed

Deroose, Jan P; Grünhagen, Dirk J; de Wilt, Johannes H W; Eggermont, Alexander M M; Verhoef, Cornelis

2015-02-01

Tumour necrosis factor-α (TNF) and melphalan based isolated limb perfusion (TM-ILP) is an attractive treatment option for advanced extremity soft tissue sarcomas (STS). This study reports on a 20-year single centre experience and discusses the evolution and changes in methodology since the introduction of TNF in ILP. We performed 306 TM-ILPs in 275 patients with extremity STS. All patients were candidates for amputation or mutilating surgery in order to achieve local control. Clinical response evaluation consisted of clinical examination and magnetic resonance imaging. To evaluate the importance of TNF-dose, treatment results of two periods (1991-2003 high dose (3-4 mg) TNF; 2003-2012 reduced dose (1-2mg) TNF) were compared. During the study period, more femoral perfusions were done instead of iliac perfusions. Reduction of TNF dose and reduction of total ILP time did not lead to different clinical response rates (70% and 69% for periods 1 and 2 respectively) or different local recurrence rates, but was associated with less local toxicity (23% and 14% for periods 1 and 2 respectively). Hospital stay was significantly reduced during the study period. There was an improved pathological response in the high dose TNF group without consequences for clinical outcome. TM-ILP remains a very effective treatment modality for limb threatening extremity STS. Moreover, reduction of dose and the growing experience in ILP led to less local toxicity and shorter hospital stay. Copyright © 2014 Elsevier Ltd. All rights reserved.

Evaluation of a Proposed Biodegradable 188Re Source for Brachytherapy Application

PubMed Central

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

2015-01-01

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

Evaluation of Kodak EDR2 film for dose verification of intensity modulated radiation therapy delivered by a static multileaf collimator.

PubMed

Zhu, X R; Jursinic, P A; Grimm, D F; Lopez, F; Rownd, J J; Gillin, M T

2002-08-01

A new type of radiographic film, Kodak EDR2 film, was evaluated for dose verification of intensity modulated radiation therapy (IMRT) delivered by a static multileaf collimator (SMLC). A sensitometric curve of EDR2 film irradiated by a 6 MV x-ray beam was compared with that of Kodak X-OMAT V (XV) film. The effects of field size, depth and dose rate on the sensitometric curve were also studied. It is found that EDR2 film is much less sensitive than XV film. In high-energy x-ray beams, the double hit process is the dominant mechanism that renders the grains on EDR2 films developable. As a result, in the dose range that is commonly used for film dosimetry for IMRT and conventional external beam therapy, the sensitometric curves of EDR2 films cannot be approximated as a linear function, OD = c * D. Within experimental uncertainty, the film sensitivity does not depend on the dose rate (50 vs 300 MU/min) or dose per pulse (from 1.0 x 10(-4) to 4.21 x 10(-4) Gy/pulse). Field sizes and depths (up to field size of 10 x 10 cm2 and depth = 10 cm) have little effect on the sensitometric curves. Percent depth doses (PDDs) for both 6 and 23 MV x rays were measured with both EDR2 and XV films and compared with ion chamber data. Film data are within 2.5% of the ion chamber results. Dose profiles measured with EDR2 film are consistent with those measured with an ion chamber. Examples of measured IMRT isodose distributions versus calculated isodoses are presented. We have used EDR2 films for verification of all IMRT patients treated by SMLC in our clinic. In most cases, with EDR2 film, actual clinical daily fraction doses can be used for verification of composite isodose distributions of SMLC-based IMRT.

Dosimetric validation and clinical implementation of two 3D dose verification systems for quality assurance in volumetric-modulated arc therapy techniques.

PubMed

Clemente-Gutiérrez, Francisco; Pérez-Vara, Consuelo

2015-03-08

A pretreatment quality assurance program for volumetric techniques should include redundant calculations and measurement-based verifications. The patient-specific quality assurance process must be based in clinically relevant metrics. The aim of this study was to show the commission, clinical implementation, and comparison of two systems that allow performing a 3D redundant dose calculation. In addition, one of them is capable of reconstructing the dose on patient anatomy from measurements taken with a 2D ion chamber array. Both systems were compared in terms of reference calibration data (absolute dose, output factors, percentage depth-dose curves, and profiles). Results were in good agreement for absolute dose values (discrepancies were below 0.5%) and output factors (mean differences were below 1%). Maximum mean discrepancies were located between 10 and 20 cm of depth for PDDs (-2.7%) and in the penumbra region for profiles (mean DTA of 1.5 mm). Validation of the systems was performed by comparing point-dose measurements with values obtained by the two systems for static, dynamic fields from AAPM TG-119 report, and 12 real VMAT plans for different anatomical sites (differences better than 1.2%). Comparisons between measurements taken with a 2D ion chamber array and results obtained by both systems for real VMAT plans were also performed (mean global gamma passing rates better than 87.0% and 97.9% for the 2%/2 mm and 3%/3 mm criteria). Clinical implementation of the systems was evaluated by comparing dose-volume parameters for all TG-119 tests and real VMAT plans with TPS values (mean differences were below 1%). In addition, comparisons between dose distributions calculated by TPS and those extracted by the two systems for real VMAT plans were also performed (mean global gamma passing rates better than 86.0% and 93.0% for the 2%/2 mm and 3%/ 3 mm criteria). The clinical use of both systems was successfully evaluated.

Effects of proton beam irradiation on seed germination and growth of soybean ( Glycine max L. Merr.)

NASA Astrophysics Data System (ADS)

Im, Juhyun; Kim, Woon Ji; Kim, Sang Hun; Ha, Bo-Keun

2017-12-01

The present study aimed to evaluate the morphological effects of proton beam irradiation on the seed germination, seedling survival, and plant growth of soybean. Seeds of three Korean elite cultivars (Kwangankong, Daepungkong, and Pungsannamulkong) were irradiated with a 57-MeV proton beam in the range of 50 - 400 Gy. The germination rates of all the varieties increased to > 95%; however, the survival rates were significantly reduced. At doses of > 300 Gy irradiation, the Daepungkong, Kwangankong, and Pungsannamulkong cultivars exhibited 39, 75, and 71% survival rates, respectively. In addition, plant height and the fresh weight of shoots and roots were significantly decreased by doses of > 100 Gy irradiation, as were the dry weights of the shoots and roots. However, SPAD values increased with increasing doses of irradiation. Abnormal plants with atypically branched stems, modified leaves, and chlorophyll mutations were observed. Based on the survival rate, plant growth inhibition, and mutation frequency, it appears that the optimum dosage of proton beam irradiation for soybean mutation breeding is between 250 and 300 Gy.

Reproducibility of CVD diamond detectors for radiotherapy dosimetry

NASA Astrophysics Data System (ADS)

Betzel, G. T.; Lansley, S. P.; McKay, D.; Meyer, J.

2012-11-01

Three in-house X-ray detectors based on diamond chemical vapor deposition (CVD) from the same manufactured batch of single crystal films were investigated for their reproducibility. Leakage current, priming dose, response dynamics, dose linearity, dependence on dose rate and angular dependence were used to evaluate differences between detectors. Slight differences were seen in leakage currents before (<1.5 pA) and after (<12 pA) irradiation. A priming dose of ˜7 Gy and rise and fall times of 2 s were found for all three detectors. Sensitivities differed by up to 10%. Dependence on dose rate were similar (∆=0.92-0.94). Angular dependence was minimal (97-102% avg.). Differences in detector performance appeared to be primarily due to film thickness, which can significantly change sensitivities (nC Gy-1) and applied fields (V μm-1) for detectors with small sensitive volumes. Results suggest that preselection of CVD diamond films according to thickness in addition to material quality would be required to avoid individual calibration, which is performed for commercially available natural diamond detectors.

The effects of oxytocin and atosiban on the modulation of heart rate in pregnant women.

PubMed

Weissman, Amir; Tobia, Rana Swed; Burke, Yechiel Z; Maxymovski, Olga; Drugan, Arie

2017-02-01

To evaluate autonomic modulation of heart rate in pregnant women treated with oxytocin to induce labor and with atosiban (an oxytocin antagonist) to arrest preterm labor. A prospective study with two cohorts: 14 pregnant women treated with atosiban for premature uterine contractions, and 28 women undergoing induction of labor with oxytocin. Computerized analyses of the electrocardiogram were performed with spectral and nonlinear dynamic analyses. Atosiban did not alter any of the variables associated with heart rate variability, whereas oxytocin showed a dose-dependent decrease in heart rate (p < 0.05) and a significant increase in all spectral variables studied (p < 0.01). Atosiban has no adverse effects on the cardiovascular system or the modulation of heart rate. Oxytocin, on the other hand, can cause a dose-dependent bradycardic effect and an increase in the spectral power, thus should be used with caution in certain pregnant women.

Surgical Responses of Medial Rectus Muscle Recession in Thyroid Eye Disease-Related Esotropia

PubMed Central

Lyu, In Jeong; Lee, Ju-Yeun; Kong, Mingui; Park, Kyung-Ah; Oh, Sei Yeul

2016-01-01

We evaluate the surgical outcomes and surgical responses of medial rectus muscle (MR) recession patients with thyroid eye disease (TED)-related esotropia (ET). The surgical dose-response curves 1 week postoperatively and at the final visit were analyzed. Univariable and multivariable linear regression analyses were applied to investigate factors influencing surgical dose-response. A total of 43 patients with TED-related ET that underwent MR recession were included. The final success rate was 86.0% and the rate of undercorrection was 14.0%. The surgical dose-response curves of TED-related ET showed a gentle slope compared with those of standard surgical tables. In the univariable model, simultaneous vertical rectus muscle recession was the only significant factor influencing surgical dose-response of MR recession in TED-related ET (β = -0.397, P = 0.044). In a model adjusted for age, sex, type of surgery, and preoperative horizontal angle of deviation, simultaneous vertical rectus muscle recession showed marginal significance (β = -0.389, P = 0.064). The surgical dose-response curve of TED-related ET was unique. Simultaneous vertical rectus muscle recession was associated with increased surgical dose-response in TED-related ET. PMID:26796354

Time-resolved in vivo luminescence dosimetry for online error detection in pulsed dose-rate brachytherapy.

PubMed

Andersen, Claus E; Nielsen, Søren Kynde; Lindegaard, Jacob Christian; Tanderup, Kari

2009-11-01

The purpose of this study is to present and evaluate a dose-verification protocol for pulsed dose-rate (PDR) brachytherapy based on in vivo time-resolved (1 s time resolution) fiber-coupled luminescence dosimetry. Five cervix cancer patients undergoing PDR brachytherapy (Varian GammaMed Plus with 192Ir) were monitored. The treatments comprised from 10 to 50 pulses (1 pulse/h) delivered by intracavitary/interstitial applicators (tandem-ring systems and/or needles). For each patient, one or two dosimetry probes were placed directly in or close to the tumor region using stainless steel or titanium needles. Each dosimeter probe consisted of a small aluminum oxide crystal attached to an optical fiber cable (1 mm outer diameter) that could guide radioluminescence (RL) and optically stimulated luminescence (OSL) from the crystal to special readout instrumentation. Positioning uncertainty and hypothetical dose-delivery errors (interchanged guide tubes or applicator movements from +/-5 to +/-15 mm) were simulated in software in order to assess the ability of the system to detect errors. For three of the patients, the authors found no significant differences (P>0.01) for comparisons between in vivo measurements and calculated reference values at the level of dose per dwell position, dose per applicator, or total dose per pulse. The standard deviations of the dose per pulse were less than 3%, indicating a stable dose delivery and a highly stable geometry of applicators and dosimeter probes during the treatments. For the two other patients, the authors noted significant deviations for three individual pulses and for one dosimeter probe. These deviations could have been due to applicator movement during the treatment and one incorrectly positioned dosimeter probe, respectively. Computer simulations showed that the likelihood of detecting a pair of interchanged guide tubes increased by a factor of 10 or more for the considered patients when going from integrating to time-resolved dose verification. The likelihood of detecting a +/-15 mm displacement error increased by a factor of 1.5 or more. In vivo fiber-coupled RL/OSL dosimetry based on detectors placed in standard brachytherapy needles was demonstrated. The time-resolved dose-rate measurements were found to provide a good way to visualize the progression and stability of PDR brachytherapy dose delivery, and time-resolved dose-rate measurements provided an increased sensitivity for detection of dose-delivery errors compared with time-integrated dosimetry.

Phase I Trial Using Proteasome Inhibitor Bortezomib and Concurrent Temozolomide and Radiotherapy for Central Nervous System Malignancies

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

Kubicek, Gregory J.; Werner-Wasik, Maria; Machtay, Mitchell

Purpose: To evaluate the toxicity and response rate of bortezomib with concurrent radiotherapy and temozolomide in the treatment of patients with central nervous system malignancies. Patients and Methods: This open-label, dose-escalation, Phase I clinical study evaluated the safety of three dose levels of intravenously administered bortezomib (0.7, 1.0, and 1.3 mg/m{sup 2}/dose) on Days 1, 4, 8, and 11 of a 21-day cycle, in addition to concurrent radiotherapy and temozolomide at a daily dose of 75 mg/m{sup 2} starting on Day 1. The primary endpoint was dose-limiting toxicity, defined as any Grade 4-5 toxicity or Grade 3 toxicity directly attributablemore » to protocol treatment, requiring hospitalization and/or radiotherapy interruption. The secondary endpoints included feasibility, non-dose-limiting toxicity, and treatment response. Results: A total of 27 patients were enrolled, 23 of whom had high-grade glioma (10 recurrent and 13 newly diagnosed). No dose-limiting toxicities were noted in any dose group, including the highest (1.3 mg/m{sup 2}/dose). The most frequent toxicities were Grade 1 and 2 stomatitis, erythema, and alopecia. All 27 patients were evaluable for response. At a median follow-up of 15.0 months, 9 patients were still alive, with a median survival of 17.4 months for all patients and 15.0 months for patients with high-grade glioma. Conclusion: Bortezomib administered at its typical 'systemic' dose (1.3 mg/m{sup 2}) is well tolerated and safe combined with temozolomide and radiotherapy when used in the treatment of central nervous system malignancies. A Phase II study to characterize efficacy is warranted.« less

Intraluminal low-dose-rate 192Ir brachytherapy combined with external beam radiotherapy and biliary stenting for unresectable extrahepatic bile duct carcinoma.

PubMed

Takamura, Akio; Saito, Hiroya; Kamada, Tadashi; Hiramatsu, Kazuhide; Takeuchi, Shuhei; Hasegawa, Masakazu; Miyamoto, Noriyuki

2003-12-01

To evaluate the results of combined-modality therapy, including external beam radiotherapy, intraluminal (192)Ir, and biliary stenting for extrahepatic bile duct carcinoma. Between 1988 and 1998, 93 patients with unresectable extrahepatic bile duct carcinoma underwent definitive radiotherapy. The dose of external beam radiotherapy was 50 Gy in 25 fractions. Low-dose-rate (192)Ir was delivered at a dose of 27-50 Gy (mean 39.2) at 0.5 cm from the source. An expandable metallic endoprosthesis was used to establish an internal bile passage. The median survival was 12 months, with a 1-, 3-, and 5-year actuarial survival rate of 50%, 10%, and 4%, respectively. Tumor length, hepatic invasion, and distant metastasis significantly affected survival. Ninety-six percent of patients could successfully remove external drainage catheters. The actuarial biliary patency rate for these patients at 1, 3, and 5 years was 52%, 29%, and 18%, respectively. Tumor length, tumor diameter and T stage were significantly associated with the patency rate. Mild-to-severe gastroduodenal complications were observed in 32 patients and were significantly associated with the active length of (192)Ir and linear source activity. Eight patients had treatment-related biliary fistula. Our combined-modality therapy provided reasonable local control and improved the quality of life of patients with extrahepatic bile duct carcinoma. Because none of the treatment characteristics had any impact on survival or biliary patency, lower dose levels and/or a localized target volume are recommended to minimize morbidity.

Solar radiation alert system : final report.

DOT National Transportation Integrated Search

2009-03-01

The Solar Radiation Alert (SRA) system continuously evaluates measurements of high-energy protons made by instruments on GOES satellites. If the measurements indicate a substantial elevation of effective dose rates at aircraft flight altitudes, the C...

Effect of Radiotherapy Dose and Volume on Relapse in Merkel Cell Cancer of the Skin

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

Foote, Matthew, E-mail: matthew_foote@health.qld.gov.a; Harvey, Jennifer; Porceddu, Sandro

Purpose: To assess the effect of radiotherapy (RT) dose and volume on relapse patterns in patients with Stage I-III Merkel cell carcinoma (MCC). Patients and Methods: This was a retrospective analysis of 112 patients diagnosed with MCC between January 2000 and December 2005 and treated with curative-intent RT. Results: Of the 112 evaluable patients, 88% had RT to the site of primary disease for gross (11%) or subclinical (78%) disease. Eighty-nine percent of patients had RT to the regional lymph nodes; in most cases (71%) this was for subclinical disease in the adjuvant or elective setting, whereas 21 patients (19%)more » were treated with RT to gross nodal disease. With a median follow-up of 3.7 years, the 2-year and 5-year overall survival rates were 72% and 53%, respectively, and the 2-year locoregional control rate was 75%. The in-field relapse rate was 3% for primary disease, and relapse was significantly lower for patients receiving {>=}50Gy (hazard ratio [HR] = 0.22; 95% confidence interval [CI], 0.06-0.86). Surgical margins did not affect the local relapse rate. The in-field relapse rate was 11% for RT to the nodes, with dose being significant for nodal gross disease (HR = 0.24; 95% CI, 0.07-0.87). Patients who did not receive elective nodal RT had a much higher rate of nodal relapse compared with those who did (HR = 6.03; 95% CI, 1.34-27.10). Conclusion: This study indicates a dose-response for subclinical and gross MCC. Doses of {>=}50Gy for subclinical disease and {>=}55Gy for gross disease should be considered. The draining nodal basin should be treated in all patients.« less

Dosimetry around metallic ports in tissue expanders in patients receiving postmastectomy radiation therapy: an ex vivo evaluation.

PubMed

Moni, Janaki; Graves-Ditman, Maria; Cederna, Paul; Griffith, Kent; Krueger, Editha A; Fraass, Benedick A; Pierce, Lori J

2004-01-01

Postmastectomy breast reconstruction can be accomplished utilizing tissue expanders and implants. However, in patients who require postoperative radiotherapy, the complication rate with tissue expander/implant reconstruction can exceed 50%. One potential cause of this high complication rate may be the metallic port in the tissue expander producing altered dosimetry in the region of the metallic device. The purpose of this study was to quantify the radiation dose distribution in the vicinity of the metallic port and determine its potential contribution to this extremely high complication rate. The absolute dosimetric effect of the tissue expander's metallic port was quantified using film and thermoluminescent dosimetry (TLD) studies with a single beam incident on a metallic port extracted from an expander. TLD measurements were performed at 11 reproducible positions on an intact expander irradiated with tangential fields. A computed tomography (CT)-based treatment plan without inhomogeneity corrections was used to derive expected doses for all TLD positions. Multiple irradiation experiments were performed for all TLD data. Confidence intervals for the dose at TLD sites with the metallic port in place were compared to the expected dose at the site without the metallic port. Film studies did not reveal a significant component of scatter around the metallic port. TLD studies of the extracted metallic port revealed highest doses within the casing of the metallic port and no consistent increased dose at the surface of the expander. No excess dose due to the metallic port in the expander was noted with the phantom TLD data. Based upon these results, it does not appear that the metallic port in tissue expanders significantly contributes to the high complication rate experienced in patients undergoing tissue expander breast reconstruction and receiving radiation therapy. Strategies designed to reduce the breast reconstruction complication rate in this clinical setting will need to focus on factors other than adjusting the dosimetry around the tissue expander metallic port.

Genital marginal failures after intensity-modulated radiation therapy (IMRT) in squamous cell anal cancer: no higher risk with IMRT when compared to 3DCRT.

PubMed

Dell'Acqua, V; Kobiela, J; Kraja, F; Leonardi, M C; Surgo, A; Zerella, M A; Arculeo, S; Fodor, C; Ricotti, R; Zampino, M G; Ravenda, S; Spinoglio, G; Biffi, R; Bazani, A; Luraschi, R; Vigorito, S; Spychalski, P; Orecchia, R; Glynne-Jones, R; Jereczek-Fossa, B A

2018-03-28

Intensity-modulated radiotherapy (IMRT) is considered the preferred option in squamous cell canal cancer (SCAC), delivering high doses to tumor volumes while minimizing dose to surrounding normal tissues. IMRT has steep dose gradients, but the technique is more demanding as deep understanding of target structures is required. To evaluate genital marginal failure in a cohort of patients with non-metastatic SCAC treated either with IMRT or 3DCRT and concurrent chemotherapy, 117 patients with SCAC were evaluated: 64 and 53 patients were treated with IMRT and 3DCRT techniques, respectively. All patients underwent clinical and radiological examination during their follow-up. Tumor response was evaluated with response evaluation criteria in solid tumors v1.1 guideline on regular basis. All patients' data were analyzed, and patients with marginal failure were identified. Concomitant chemotherapy was administered in 97 and 77.4% of patients in the IMRT and 3DCRT groups, respectively. In the IMRT group, the median follow-up was 25 months (range 6-78). Progressive disease was registered in 15.6% of patients; infield recurrence, distant recurrence and both infield recurrence and distant recurrence were identified in 5, 4 and 1 patient, respectively. Two out of 64 patients (3.1%) had marginal failures, localized at vagina/recto-vaginal septum and left perineal region. In the 3DCRT group, the median follow-up was 71.3 months (range 6-194 months). Two out of 53 patients (3.8%) had marginal failures, localized at recto-vaginal septum and perigenital structures. The rate of marginal failures was comparable in IMRT and 3DCRT groups (χ 2 test p = 0.85). In this series, the use of IMRT for the treatment of SCAC did not increase the rate of marginal failures offering improved dose conformity to the target. Dose constraints should be applied with caution-particularly in females with involvement of the vagina or the vaginal septum.

High resolution digital autoradiographic and dosimetric analysis of heterogeneous radioactivity distribution in xenografted prostate tumors.

PubMed

Timmermand, Oskar V; Nilsson, Jenny; Strand, Sven-Erik; Elgqvist, Jörgen

2016-12-01

The first main aim of this study was to illustrate the absorbed dose rate distribution from 177 Lu in sections of xenografted prostate cancer (PCa) tumors using high resolution digital autoradiography (DAR) and compare it with hypothetical identical radioactivity distributions of 90 Y or 7 MeV alpha-particles. Three dosimetry models based on either dose point kernels or Monte Carlo simulations were used and evaluated. The second and overlapping aim, was to perform DAR imaging and dosimetric analysis of the distribution of radioactivity, and hence the absorbed dose rate, in tumor sections at an early time point after injection during radioimmunotherapy using 177 Lu-h11B6, directed against the human kallikrein 2 antigen. Male immunodeficient BALB/c nude mice, aged 6-8 w, were inoculated by subcutaneous injection of ∼10 7 LNCaP cells in a 200 μl suspension of a 1:1 mixture of medium and Matrigel. The antibody h11B6 was conjugated with the chelator CHX-A″-DTPA after which conjugated h11B6 was mixed with 177 LuCl 3 . The incubation was performed at room temperature for 2 h, after which the labeling was terminated and the solution was purified on a NAP-5 column. About 20 MBq 177 Lu-h11B6 was injected intravenously in the tail vein. At approximately 10 h postinjection (hpi), the mice were sacrificed and one tumor was collected from each of the five animals and cryosectioned into 10 μm thick slices. The tumor slices were measured and imaged using the DAR MicroImager system and the M3Vision software. Then the absorbed dose rate was calculated using a dose point kernel generated with the Monte Carlo code gate v7.0. The DAR system produced high resolution images of the radioactivity distribution, close to the resolution of single PCa cells. The DAR images revealed a pronounced heterogeneous radioactivity distribution, i.e., count rate per area, in the tumors, indicated by the normalized intensity variations along cross sections as mean ± SD: 0.15 ± 0.15, 0.20 ± 0.18, 0.12 ± 0.17, 0.15 ± 0.16, and 0.23 ± 0.22, for each tumor section, respectively. The absorbed dose rate distribution for 177 Lu at the time of dissection 10 hpi showed a maximum value of 2.9 ± 0.4 Gy/h (mean ± SD), compared to 6.0 ± 0.9 and 159 ± 25 Gy/h for the hypothetical 90 Y and 7 MeV alpha-particle cases assuming the same count rate densities. Mean absorbed dose rate values were 0.13, 0.53, and 6.43 Gy/h for 177 Lu, 90 Y, and alpha-particles, respectively. The initial uptake of 177 Lu-h11B6 produces a high absorbed dose rate, which is important for a successful therapeutic outcome. The hypothetical 90 Y case indicates a less heterogeneous absorbed dose rate distribution and a higher mean absorbed dose rate compared to 177 Lu, although with a potentially increased irradiation of surrounding healthy tissue. The hypothetical alpha-particle case indicates the possibility of a higher maximum absorbed dose rate, although with a more heterogeneous absorbed dose rate distribution.

Efficacy of Low-Dose Corticosteroid Therapy Versus High-Dose Corticosteroid Therapy in Bell's Palsy in Children.

PubMed

Arican, Pinar; Dundar, Nihal Olgac; Gencpinar, Pinar; Cavusoglu, Dilek

2017-01-01

Bell's palsy is the most common cause of acute peripheral facial nerve paralysis, but the optimal dose of corticosteroids in pediatric patients is still unclear. This retrospective study aimed to evaluate the efficacy of low-dose corticosteroid therapy compared with high-dose corticosteroid therapy in children with Bell's palsy. Patients were divided into 2 groups based on the dose of oral prednisolone regimen initiated. The severity of idiopathic facial nerve paralysis was graded according to the House-Brackmann Grading Scale. The patients were re-assessed in terms of recovery rate at the first, third, and sixth months of treatment. There was no significant difference in complete recovery between the 2 groups after 1, 3, and 6 months of treatment. In our study, we concluded that even at a dose of 1 mg/kg/d, oral prednisolone was highly effective in the treatment of Bell's palsy in children.

Evaluation of optimal parameters for using low-dose computed tomography to diagnose urolithiasis

NASA Astrophysics Data System (ADS)

Chen, Hui-Hsien; Yu, Cheng-Ching; Hsu, Fang-Yuh

2017-11-01

Urolithiasis is a common disease; patients suspected of suffering from urolithiasis will be examined by abdomen x-ray, Sono, Intraudio Videonous Urography (IVU) and Computed Tomography (CT). The detection rates for calculus in above examinations are respectively: 50-70% (x-ray), 50-60% (Sono), 70-90% (IVU) and 97% (CT). In addition, the effective doses are respectively: 0.63 mSv (x-ray), no radiation dose (Sono), 2.6 mSv (IVU) and 8-16 mSv (CT). Although CT has the highest detection rate for calculus, it also has the highest radiation dose. This research sought to lower the radiation dose by using CT scans with different dose conditions of standard dose (SD), 50% SD, 25% SD, and 15% SD to diagnose patients who suffer from urolithiasis and thus explore the feasibility of examining urolithiasis via CT with lower dose conditions. This research simulated the examination of patients with RANDO phantom, collocating PMMA slice phantom and pig's kidney. Fake calculuses made of five different materials of different sizes were put into the phantom and scanned individually. The results of the scanned images were given to two physicians who had many years of diagnostic experience to interpret the urolithiasis images. This study explored the different image qualities of CT with different dose conditions. In addition, this research used thermoluminescent dosimeters (TLD) to measure the radiation doses and compared the results with the dose values shown on the screen of the CT scanner to estimate the dose conversion factor (k). The research results showed that a low-dose CT was able to provide good image quality and thus have a lower radiation dose. Therefore, a low-dose CT is suggested the main examination method to diagnose patients with urolithiasis.

Determination of MLC model parameters for Monaco using commercial diode arrays.

PubMed

Kinsella, Paul; Shields, Laura; McCavana, Patrick; McClean, Brendan; Langan, Brian

2016-07-08

Multileaf collimators (MLCs) need to be characterized accurately in treatment planning systems to facilitate accurate intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT). The aim of this study was to examine the use of MapCHECK 2 and ArcCHECK diode arrays for optimizing MLC parameters in Monaco X-ray voxel Monte Carlo (XVMC) dose calculation algorithm. A series of radiation test beams designed to evaluate MLC model parameters were delivered to MapCHECK 2, ArcCHECK, and EBT3 Gafchromic film for comparison. Initial comparison of the calculated and ArcCHECK-measured dose distributions revealed it was unclear how to change the MLC parameters to gain agreement. This ambiguity arose due to an insufficient sampling of the test field dose distributions and unexpected discrepancies in the open parts of some test fields. Consequently, the XVMC MLC parameters were optimized based on MapCHECK 2 measurements. Gafchromic EBT3 film was used to verify the accuracy of MapCHECK 2 measured dose distributions. It was found that adjustment of the MLC parameters from their default values resulted in improved global gamma analysis pass rates for MapCHECK 2 measurements versus calculated dose. The lowest pass rate of any MLC-modulated test beam improved from 68.5% to 93.5% with 3% and 2 mm gamma criteria. Given the close agreement of the optimized model to both MapCHECK 2 and film, the optimized model was used as a benchmark to highlight the relatively large discrepancies in some of the test field dose distributions found with ArcCHECK. Comparison between the optimized model-calculated dose and ArcCHECK-measured dose resulted in global gamma pass rates which ranged from 70.0%-97.9% for gamma criteria of 3% and 2 mm. The simple square fields yielded high pass rates. The lower gamma pass rates were attributed to the ArcCHECK overestimating the dose in-field for the rectangular test fields whose long axis was parallel to the long axis of the ArcCHECK. Considering ArcCHECK measurement issues and the lower gamma pass rates for the MLC-modulated test beams, it was concluded that MapCHECK 2 was a more suitable detector than ArcCHECK for the optimization process. © 2016 The Authors

Evaluation of polymer gels and MRI as a 3-D dosimeter for intensity-modulated radiation therapy.

PubMed

Low, D A; Dempsey, J F; Venkatesan, R; Mutic, S; Markman, J; Mark Haacke, E; Purdy, J A

1999-08-01

BANG gel (MGS Research, Inc., Guilford, CT) has been evaluated for measuring intensity-modulated radiation therapy (IMRT) dose distributions. Treatment plans with target doses of 1500 cGy were generated by the Peacock IMRT system (NOMOS Corp., Sewickley, PA) using test target volumes. The gels were enclosed in 13 cm outer diameter cylindrical glass vessels. Dose calibration was conducted using seven smaller (4 cm diameter) cylindrical glass vessels irradiated to 0-1800 cGy in 300 cGy increments. Three-dimensional maps of the proton relaxation rate R2 were obtained using a 1.5 T magnetic resonance imaging (MRI) system (Siemens Medical Systems, Erlangen, Germany) and correlated with dose. A Hahn spin echo sequence was used with TR = 3 s, TE = 20 and 100 ms, NEX = 1, using 1 x 1 x 3 mm3 voxels. The MRI measurements were repeated weekly to identify the gel-aging characteristics. Ionization chamber, thermoluminescent dosimetry (TLD), and film dosimetry measurements of the IMRT dose distributions were obtained to compare against the gel results. The other dosimeters were used in a phantom with the same external cross-section as the gel phantom. The irradiated R2 values of the large vessels did not precisely track the smaller vessels, so the ionization chamber measurements were used to normalize the gel dose distributions. The point-to-point standard deviation of the gel dose measurements was 7.0 cGy. When compared with the ionization chamber measurements averaged over the chamber volume, 1% agreement was obtained. Comparisons against radiographic film dose distribution measurements and the treatment planning dose distribution calculation were used to determine the spatial localization accuracy of the gel and MRI. Spatial localization was better than 2 mm, and the dose was accurately determined by the gel both within and outside the target. The TLD chips were placed throughout the phantom to determine gel measurement precision in high- and low-dose regions. A multidimensional dose comparison tool that simultaneously examines the dose-difference and distance-to-agreement was used to evaluate the gel in both low-and high-dose gradient regions. When 3% and 3 mm criteria were used for the comparisons, more than 90% of the TLD measurements agreed with the gel, with the worst of 309 TLD chip measurements disagreeing by 40% of the criteria. All four MRI measurement session gel-measured dose distributions were compared to evaluate the time behavior of the gel. The low-dose regions were evaluated by comparison with TLD measurements at selected points, while high-dose regions were evaluated by directly comparing measured dose distributions. Tests using the multidimensional comparison tool showed detectable degradation beyond one week postirradiation, but all low-dose measurements passed relative to the test criteria and the dose distributions showed few regions that failed.

Enhanced Low Dose Rate Sensitivity at Ultra-Low Dose Rates

NASA Technical Reports Server (NTRS)

Chen, Dakai; Pease, Ronald; Forney, James; Carts, Martin; Phan, Anthony; Cox, Stephen; Kruckmeyer, Kriby; Burns, Sam; Albarian, Rafi; Holcombe, Bruce;

The Effects of ELDRS at Ultra-Low Dose Rates

NASA Technical Reports Server (NTRS)

Chen, Dakai; Forney, James; Carts, Martin; Phan, Anthony; Pease, Ronald; Kruckmeyer, Kirby; Cox, Stephen; LaBel, Kenneth; Burns, Samuel; Albarian, Rafi;

[Developments in brachytherapy].

PubMed

Ikeda, H

1995-09-01

Brachytherapy is one of the ideal methods of radiotherapy because of the concentration of a high dose on the target. Recent developments, including induction of afterloading method, utilization of small-sized high-activity sources such as Iridium-192, and induction of high technology and computerization, have made for shortening of irradiation time and source handling, which has led to easier management of the patient during treatment. Dose distribution at high dose rate (HDR) is at least as good as that of low dose rate (LDR), and selection of fractionation and treatment time assures even greater biological effects on hypoxic tumor cells than LDR. Experience with HDR brachytherapy in uterine cervix cancer using Cobalt-60 during the past 20 years in this country has gradually been evaluated in U.S. and Europe. The indications for HDR treatment have extended to esophagus, bronchus, bile duct, brain, intraoperative placement of source guide, and perineal region using templates, as well as the conventional use for uterus, tongue and so on.

Prophylactic low-dose aspirin is effective antithrombotic therapy for combination treatments of thalidomide or lenalidomide in myeloma.

PubMed

Niesvizky, Ruben; Martínez-Baños, Déborah; Jalbrzikowski, Jessica; Christos, Paul; Furst, Jessica; De Sancho, Maria; Mark, Tomer; Pearse, Roger; Mazumdar, Madhu; Zafar, Faiza; Pekle, Karen; Leonard, John; Jayabalan, David; Coleman, Morton

2007-12-01

Multiple myeloma (MM) patients have a propensity for thromboembolic events (TE), and treatment with thalidomide/dexamethasone or lenalidomide/dexamethasone increases this risk. This report describes the use of low-dose aspirin (81 mg) as primary thromboprophylaxis in three series of MM patients receiving thalidomide or lenalidomide with other drugs. In the first regimen (clarithromycin, thalidomide, dexamethasone), initiation of low-dose aspirin negated the occurrence of any further TE. In a second study, prophylactic aspirin given with thalidomide/dexamethasone resulted in a rate of TE similar to that seen with dexamethasone alone (without aspirin). A third study (n = 72) evaluated thrombosis rates with aspirin and a lenalidomide-containing regimen (clarithromycin, lenalidomide, dexamethasone). Of nine occurrences of thromboembolism, five were associated with aspirin interruption or poor compliance. Low-dose aspirin appears to reduce the incidence of thrombosis with these regimens. Routine use of aspirin as antithrombotic prophylaxis in MM patients receiving immunomodulatory drugs with corticosteroids is warranted.

FLUKA simulation of TEPC response to cosmic radiation.

PubMed

Beck, P; Ferrari, A; Pelliccioni, M; Rollet, S; Villari, R

2005-01-01

The aircrew exposure to cosmic radiation can be assessed by calculation with codes validated by measurements. However, the relationship between doses in the free atmosphere, as calculated by the codes and from results of measurements performed within the aircraft, is still unclear. The response of a tissue-equivalent proportional counter (TEPC) has already been simulated successfully by the Monte Carlo transport code FLUKA. Absorbed dose rate and ambient dose equivalent rate distributions as functions of lineal energy have been simulated for several reference sources and mixed radiation fields. The agreement between simulation and measurements has been well demonstrated. In order to evaluate the influence of aircraft structures on aircrew exposure assessment, the response of TEPC in the free atmosphere and on-board is now simulated. The calculated results are discussed and compared with other calculations and measurements.

Phase 1 trial evaluating cisplatin, gemcitabine, and veliparib in 2 patient cohorts: Germline BRCA mutation carriers and wild-type BRCA pancreatic ductal adenocarcinoma.

PubMed

O'Reilly, Eileen M; Lee, Jonathan W; Lowery, Maeve A; Capanu, Marinela; Stadler, Zsofia K; Moore, Malcolm J; Dhani, Neesha; Kindler, Hedy L; Estrella, Hayley; Maynard, Hannah; Golan, Talia; Segal, Amiel; Salo-Mullen, Erin E; Yu, Kenneth H; Epstein, Andrew S; Segal, Michal; Brenner, Robin; Do, Richard K; Chen, Alice P; Tang, Laura H; Kelsen, David P

2018-04-01

A phase 1 trial was used to evaluate a combination of cisplatin, gemcitabine, and escalating doses of veliparib in patients with untreated advanced pancreatic ductal adenocarcinoma (PDAC) in 2 cohorts: a germline BRCA1/2-mutated (BRCA+) cohort and a wild-type BRCA (BRCA-) cohort. The aims were to determine the safety, dose-limiting toxicities (DLTs), maximum tolerated dose, and recommended phase 2 dose (RP2D) of veliparib combined with cisplatin and gemcitabine and to assess the antitumor efficacy (Response Evaluation Criteria in Solid Tumors, version 1.1) and overall survival. Gemcitabine and cisplatin were dosed at 600 and 25 mg/m 2 , respectively, over 30 minutes on days 3 and 10 of a 21-day cycle. Four dose levels of veliparib were evaluated: 20 (dose level 0), 40 (dose level 1), and 80 mg (dose level 2) given orally twice daily on days 1 to 12 and 80 mg given twice daily on days 1 to 21 (dose level 2A [DL2A]). Seventeen patients were enrolled: 9 BRCA+ patients, 7 BRCA- patients, and 1 patient with an unknown status. DLTs were reached at DL2A (80 mg twice daily on days 1 to 21). Two of the 5 patients in this cohort (40%) experienced grade 4 neutropenia and thrombocytopenia. Two grade 5 events occurred on protocol. The objective response rate in the BRCA+ cohort was 7 of 9 (77.8%). The median overall survival for BRCA+ patients was 23.3 months (95% confidence interval [CI], 3.8-30.2 months). The median overall survival for BRCA- patients was 11 months (95% CI, 1.5-12.1 months). The RP2D of veliparib was 80 mg by mouth twice daily on days 1 to 12 in combination with cisplatin and gemcitabine; the DLT was myelosuppression. Substantial antitumor activity was seen in BRCA+ PDAC. A randomized phase 2 trial is currently evaluating cisplatin and gemcitabine with and without veliparib for BRCA+ PDAC (NCT01585805). Cancer 2018;124:1374-82. © 2018 American Cancer Society. © 2018 American Cancer Society.

RadNuc: A graphical user interface to deliver dose rate patterns encountered in nuclear medicine with a 137Cs irradiator

PubMed Central

Pasternack, Jordan B.; Howell, Roger W.

2012-01-01

The temporal variations in absorbed dose rates to organs and tissues in the body are very large in diagnostic and therapeutic nuclear medicine. The response of biological endpoints of relevance to radiation safety and therapeutic efficacy are generally modulated by dose rate. Therefore, it is important to understand how the complex dose rate patterns encountered in nuclear medicine impact relevant biological responses. Accordingly, a graphical user interface (GUI) was created to control a cesium-137 irradiator to deliver such dose rate patterns. Methods Visual Basic 6.0 was used to create a user-friendly GUI to control the dose rate by varying the thickness of a mercury attenuator. The GUI facilitates the delivery of a number of dose rate patterns including constant, exponential increase or decrease, and multi-component exponential. Extensive visual feedback is provided by the GUI during both the planning and delivery stages. Results The GUI controlled irradiator can achieve a maximum dose rate of 40 cGy/hr and a minimum dose rate of 0.01 cGy/hr. Addition of machined lead blocks can be used to further reduce the minimum dose rate to 0.0001 cGy/hr. Measured dose rate patterns differed from programmed dose rate patterns in total dose by 3.2% to 8.4%. Conclusion The GUI controlled irradiator is able to accurately create dose rate patterns encountered in nuclear medicine and other related fields. This makes it an invaluable tool for studying the effects of chronic constant and variable low dose rates on biological tissues in the contexts of both radiation protection and clinical administration of internal radionuclides. PMID:23265668

RadNuc: a graphical user interface to deliver dose rate patterns encountered in nuclear medicine with a 137Cs irradiator.

PubMed

Pasternack, Jordan B; Howell, Roger W

2013-02-01

The temporal variations in absorbed dose rates to organs and tissues in the body are very large in diagnostic and therapeutic nuclear medicine. The response of biological endpoints of relevance to radiation safety and therapeutic efficacy is generally modulated by dose rate. Therefore, it is important to understand how the complex dose rate patterns encountered in nuclear medicine impact relevant biological responses. Accordingly, a graphical user interface (GUI) was created to control a cesium-137 irradiator to deliver such dose rate patterns. Visual Basic 6.0 was used to create a user-friendly GUI to control the dose rate by varying the thickness of a mercury attenuator. The GUI facilitates the delivery of a number of dose rate patterns including constant, exponential increase or decrease, and multi-component exponential. Extensive visual feedback is provided by the GUI during both the planning and delivery stages. The GUI controlled irradiator can achieve a maximum dose rate of 40 cGy/h and a minimum dose rate of 0.01 cGy/h. Addition of machined lead blocks can be used to further reduce the minimum dose rate to 0.0001 cGy/h. Measured dose rate patterns differed from programmed dose rate patterns in total dose by 3.2% to 8.4%. The GUI controlled irradiator is able to accurately create dose rate patterns encountered in nuclear medicine and other related fields. This makes it an invaluable tool for studying the effects of chronic constant and variable low dose rates on biological tissues in the contexts of both radiation protection and clinical administration of internal radionuclides. Copyright © 2013 Elsevier Inc. All rights reserved.

Exploring gastric emptying rate in minipigs: Effect of food type and pre-dosing of metoclopramide.

PubMed

Henze, Laura J; Griffin, Brendan T; Christiansen, Martin; Bundgaard, Christoffer; Langguth, Peter; Holm, René

2018-06-15

The present study investigated the gastric emptying rate in Göttingen minipigs pre- and post-prandial and evaluated the effect of metoclopramide on the same parameter, using paracetamol as an absorption marker. The pharmacokinetic evaluation of the obtained plasma concentration data for paracetamol demonstrated that the fastest gastric emptying rate was observed in the animals that were allowed access to normal pig food. There was no significant difference in the stomach emptying rate observed between fasted and fed minipigs, when fed either with a FDA standard breakfast or a nutritional energy drink. Pre-dosing minipigs with metoclopramide (0.2 or 0.4 mg/kg) did not demonstrate any effect on gastric emptying in either the fasted or fed state. The data in the present study demonstrated a relatively prolonged gastric emptying rate in mini-pigs both in the fasted and fed state, hence when conducting pharmacokinetic studies using minipigs, this should be taken into account when planning the plasma sampling time points. Further, as no difference could be observed in gastric emptying rate as a function of food, the data also suggest that the Göttingen mini-pigs seems less suited to predict for food effect studies than other species. Copyright © 2018 Elsevier B.V. All rights reserved.

A randomized, double-blind, dose-finding Phase II study to evaluate immunogenicity and safety of the third generation smallpox vaccine candidate IMVAMUNE®

PubMed Central

von Krempelhuber, Alfred; Vollmar, Jens; Pokorny, Rolf; Rapp, Petra; Wulff, Niels; Petzold, Barbara; Handley, Amanda; Mateo, Lyn; Siersbol, Henriette; Kollaritsch, Herwig; Chaplin, Paul

2009-01-01

IMVAMUNE® is a Modified Vaccinia Ankara-based virus that is being developed as a safer 3rd generation smallpox vaccine. In order to determine the optimal dose for further development, a double-blind, randomized Phase II trial was performed testing three different doses of IMVAMUNE® in 164 healthy volunteers. All three IMVAMUNE® doses displayed a favourable safety profile, with local reactions as the most frequent observation. The 1×108 TCID50 IMVAMUNE® dose induced a total antibody response in 94% of the subjects following the first vaccination and the highest peak seroconversion rates by ELISA (100%) and PRNT (71%). This IMVAMUNE® dose was considered to be optimal for the further clinical development of this highly attenuated poxvirus as a safer smallpox vaccine. PMID:19944151

A descriptive feasibility study to evaluate scheduled oral analgesic dosing at home for the management of postoperative pain in preschool children following tonsillectomy.

PubMed

Sutters, Kimberly A; Holdridge-Zeuner, Danielle; Waite, Steven; Paul, Steven M; Savedra, Marilyn C; Lanier, Brent; Mahoney, Karla; Miaskowski, Christine

2012-03-01

The purpose of this study, in a sample of preschool children (ages 3-5 years; N = 47), was to evaluate the feasibility of scheduled analgesic dosing following outpatient tonsillectomy in order to optimize pain management. Parents were instructed to give their child acetaminophen with hydrocodone (167 mg/5 mL) every 4 hours around the clock for the first 3 days following surgery. Parents recorded ratings of their child's pain with/without swallowing using the Faces, Legs, Activity, Cry, and Consolability (FLACC) behavioral pain scale, pain relief ratings, and severity of analgesic side effects in a home diary. Audiotaped interviews were conducted with parents to document descriptions of their experiences in managing their child's pain at home. Mean FLACC scores with/without swallowing were less than two at each measurement time and pain relief scores increased over time. Total analgesic dose decreased, and the number of missed doses increased over the first 3 days after surgery. Moderate-to-severe daytime sedation, nausea, vomiting, and constipation were reported by parents. Study results suggest that acetaminophen with hydrocodone is effective in relieving preschool children's pain following tonsillectomy and that parental adherence to a scheduled analgesic regimen decreases over time. Time-contingent dosing was associated with moderate to severe side effects and should be addressed in discharge teaching with parents. Findings provide insight into parents' perspective of pain management at home following tonsillectomy and methods for relieving their child's pain. Wiley Periodicals, Inc.

Evaluation of Biologic Effective Dose and Schedule of Fractionation for Preoperative Radiotherapy for Rectal Cancer: Meta-Analyses and Meta-Regression;Rectal cancer; Preoperative radiotherapy; Biologic effective dose; Meta-analysis

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

Arruda Viani, Gustavo, E-mail: gusviani@gmail.com; Stefano, Eduardo Jose; Vendito Soares, Francisco

2011-07-15

Purpose: To evaluate whether the risk of local recurrence depends on the biologic effective dose (BED) or fractionation dose in patients with resectable rectal cancer undergoing preoperative radiotherapy (RT) compared with surgery alone. Methods and Materials: A meta-analysis of randomized controlled trials (RCTs) was performed. The MEDLINE, Embase, CancerLit, and Cochrane Library databases were systematically searched for evidence. To evaluate the dose-response relationship, we conducted a meta-regression analysis. Four subgroups were created: Group 1, RCTs with a BED >30 Gy{sub 10} and a short RT schedule; Group 2, RCTs with BED >30 Gy{sub 10} and a long RT schedule; Groupmore » 3, RCTs with BED {<=}30 Gy{sub 10} and a short RT schedule; and Group 4, RCTs with BED {<=}30 Gy{sub 10} and a long RT schedule. Results: Our review identified 21 RCTs, yielding 9,097 patients. The pooled results from these 21 randomized trials of preoperative RT showed a significant reduction in mortality for groups 1 (p = .004) and 2 (p = .03). For local recurrence, the results were also significant in groups 1 (p = .00001) and 2 (p = .00001).The only subgroup that showed a greater sphincter preservation (SP) rate than surgery was group 2 (p = .03). The dose-response curve was linear (p = .006), and RT decreased the risk of local recurrence by about 1.7% for each Gy{sub 10} of BED. Conclusion: Our data have shown that RT with a BED of >30 Gy{sub 10} is more efficient in reducing local recurrence and mortality rates than a BED of {<=}30 Gy{sub 10}, independent of the schedule of fractionation used. A long RT schedule with a BED of >30 Gy{sub 10} should be recommended for sphincter preservation.« less

High-dose sequential epirubicin and cyclophosphamide with peripheral blood stem cell support for advanced breast cancer: results of a phase II study

PubMed Central

Cottu, P H; Extra, J M; Espie, M; Marolleau, J P; Roquancourt, A de; Makke, J; Miclea, J M; Laurence, V; Mayeur, D; Lerebours, F; Cuvier, C; Marty, M

2001-01-01

The aim of this study was to evaluate the feasibility of a high-dose intensity and high-dose density multicycle epirubicin and cyclophosphamide regimen with peripheral blood stem cells (PBSC) and haematopoietic growth factor (G-CSF) support in advanced breast cancer patients. From August 1994 to September 1999, 56 breast cancer patients (8 stage IIIB and 48 stage IV) received 205 courses of cyclophosphamide 3 g m−2and epirubicin 100 mg m−2every 14 days. G-CSF 5 μg kg−1day−1was administered from day 3 to neutrophil recovery. 4 courses were planned. PBSC were collected after course 1, and reinfused after courses 3 and 4, with ≥ 2 × 106CD34+ PBSC kg−1required for each reinfusion. 48 patients (86%) received all 4 planned courses. Early withdrawal was consecutive to infectious complications (n= 4), severe asthenia (n= 3), haemorrhagic cystitis (n= 1). A median number of 10.8 × 106CD34+ PBSC kg−1(range, 3–80) was harvested with 1 or 2 apheresis in 48 patients (94%). Median relative dose intensity was 91.3% (range, 72–102%). Grade 4 neutrophil toxicity was observed in 100% of patients. Febrile neutropenia was observed in 40% of courses (median duration 2 days). Red blood cells and platelets had to be transfused in 54% and 27% of courses, respectively. There were no toxic deaths. Objective response rate was 69% in stage IV patients (31/45 evaluable pts), with a 16% complete response rate. Their median progression-free and overall survivals were 22.5 and 37 months, respectively. This epirubicine-containing high-dose regimen appeared feasible, albeit with high toxicity. Time-related progression parameters exceed commonly reported ones. Controlled studies of upfront sequential high-dose chemotherapy are still needed to evaluate its real benefit. © 2001 Cancer Research Campaign PMID:11720455

High-dose transdermal nicotine replacement for tobacco cessation.

PubMed

Brokowski, Laurie; Chen, Jiahui; Tanner, Sara

2014-04-15

The safety and efficacy of high-dose transdermal nicotine-replacement therapy (NRT) for the treatment of tobacco-use cessation were reviewed. Transdermal nicotine doses of 7, 14, and 21 mg daily are approved by the Food and Drug Administration for use in tobacco cessation. However, studies have suggested that these doses are more adequate for people who smoke fewer than 20 cigarettes per day. A literature search was conducted to identify English-language studies that evaluated the use of transdermal nicotine doses of ≥42 mg daily. A total of 11 articles were identified, representing 10 separate trials. In terms of safety, the majority of the trials had no reports of serious adverse events related to transdermal NRT at doses of ≥42 mg daily. A dose-response relationship with adverse events occurred in most trials. In terms of efficacy, a numerically higher abstinence rate was achieved with high-dose transdermal NRT in all trials but 1. However, none of the studies showed significant differences in final abstinence rates at follow-up. Some reasons why statistical significance was not achieved in these trials may be related to the limitations of these trials, such as their small samples and the lack of a power calculation. A more robust trial is needed to support higher nicotine transdermal doses in tobacco cessation and to help elucidate which patient population would be most suitable for their use. The safety and efficacy of high-dose transdermal NRT for tobacco cessation have not been established in the medical literature.

CKD-EPI equation: A suitable Glomerular Filtration Rate estimate for drug dosing in HIV-infected patients.

PubMed

Gagneux-Brunon, A; Botelho-Nevers, E; Delanaye, P; Lucht, F; Frésard, A; Cazorla, C; Guglielminotti, C; Fafin, C; Mariat, C; Moranne, O

2017-06-01

To evaluate concordance between glomerular filtration rate (GFR) estimates (Cockcroft and Gault, modification of diet in renal diseases, chronic kidney disease epidemiology study group equations) for drug dosing in HIV-infected patients. We performed a monocentric study. GFR was measured using the gold standard method (plasma clearance of iohexol) in 230 HIV-infected patients. Concordance rate was evaluated between measured GFR (mGFR) and estimated GFR (eGFR) for different GFR categories (GFR>90 mL/min, GFR<90 mL/min, GFR>70 mL/min, and GFR<70 mL/min). MDRD and CKD-EPI were used with and without indexation to body surface area (BSA). Mean age was 48±10 years, mean mGFR was 101±26 mL/min. Concordance between mGFR and eGFR estimated with CG, CKD-EPI (indexed and not indexed to BSA), or MDRD equations (not indexed to BSA) was similar (73%, 73%, 74%, and 73% respectively) for a breakpoint value of 90 mL/min for GFR. At this value, the concordance rate between mGFR and MDRD indexed to BSA was significantly lower (65%, P<0.05). Using 70 mL/min of GFR as the breakpoint value, all equations had similar concordance rates with mGFR (with or without indexation to BSA). CKD-EPI equation has the same concordance with GFR and with CG when used for drug dosing. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

238PuO 2 Fuel and Dosimetry

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

Mayo, Douglas R.; Rawool-Sullivan, Mohini; Garner, Scott Edward

2016-06-01

238Pu is an ideal material for use as a heat source with its half-life of 87.7 years and copious particle emissions. 238Pu radioisotope thermoelectric generators (RTGs) have found use for pacemakers, Apollo Space missions, Mars rovers, and Voyager spacecraft. In evaluating the dose to personnel and components near a 238Pu-based RTG, a number of additional nuclides and their daughter products must be considered to get an accurate estimate for γ-dose, and the amount of 17O and 18O for the neutron-dose must be considered. This paper looks at the contributing nuclides and their daughter products that add the most to themore » dose rates.« less

Does Early Resumption of Low-Dose Aspirin After Evacuation of Chronic Subdural Hematoma With Burr-Hole Drainage Lead to Higher Recurrence Rates?

PubMed

Kamenova, Maria; Lutz, Katharina; Schaedelin, Sabine; Fandino, Javier; Mariani, Luigi; Soleman, Jehuda

2016-11-01

Antiplatelet therapy in patients with chronic subdural hematoma (cSDH) presents significant neurosurgical challenges. Given the lack of guidelines regarding perioperative management with antiplatelet therapy, it is difficult to balance the patient's increased cardiovascular risk and prevalence of cSDH. To better understand the risk and recurrence rates related to resuming low-dose acetylsalicylic acid (ASA) by evaluating our patients' resumption of low-dose ASA at various times after burr-hole drainage of the hematoma. In our retrospective study, 140 consecutive patients taking low-dose ASA undergoing surgical evacuation of cSDH were included. Data included baseline characteristics and rates of recurrence, morbidity, and mortality. A multivariate logistic regression model analyzed the association between ASA resumption time and recurrence rates. No statistically significant association was observed between early postoperative resumption of low-dose ASA and recurrence of cSDH (odds ratio, 1.01; 95% confidence interval, 1.001-1.022; P = .06). Corresponding odds ratios and risk differences for restarting ASA treatment on postoperative days 1, 7, 14, 21, 28, 35, or 42 were estimated at 1.53 and 5.9%, 1.42 and 5.1%, 1.33 and 4.1%, 1.23 and 3.2%, 1.15 and 2.2%, 1.07 and 1.1%, and 1.01 and 0.2%, respectively (P > .05). Cardiovascular event rates, surgical morbidity, and mortality did not significantly differ between patients with or without ASA therapy. Given the few published studies regarding ASA use in cranial neurosurgery, our findings elucidate one issue, showing comparable recurrence rates with early or late resumption of low-dose ASA after burr-hole evacuation of cSDH. ASA, acetylsalicylic acidCAD, coronary artery diseaseCI, confidence intervalcSDH, chronic subdural hematomaGCS, Glasgow Coma ScalemRS, modified Rankin ScaleOR, odds ratioRD, risk difference.

Boosting subsurface life: is subseafloor sediment a natural catalyst for radiolytic hydrogen production?

NASA Astrophysics Data System (ADS)

Sauvage, J.; Graham, D.; Spivack, A. J.; Dunlea, A. G.; Murray, R. W.; D'Hondt, S.

2014-12-01

Naturally occurring production of molecular hydrogen (H2) by water radiolysis may be a fundamentally important source of electron donors (energy) for life in subsurface environments where organic matter is scarce. Previous studies with very high gamma radiation rates and wet mineral phases have reported high H2 production relative to production from water radiolysis in the absence of solid phases. Numerical calculations by other previous studies have predicted enhanced H2 production from seawater radiolysis relative to pure water radiolysis, due to the interaction of anions with hydroxyl radicals. Given these reports, the potential catalytic influences of solid and dissolved chemical phases on radiolytic H2 production need to be carefully quantified in order to fully evaluate the role of radiolytic H2 as a microbial energy source. For such quantification, we undertook gamma-irradiation experiments with pure water, deep ocean water and mixtures (slurries, φ = 0.85) of seawater with: North Pacific abyssal clay and calcareous oozes, coastal sediment, zirconium dioxide, and zeolite. We carried out our experiments at the Rhode Island Nuclear Science Center using a 37Cesium source at low dose rates (up to 0.1 Gy/hr). Our results to date include the following. First, the per-dose radiolytic H2 yield of pure water at low dose rates is directly comparable to the per-dose yield at much higher dose rates (ca. 1 kGy/hr); this result indicates that H2 production rate is linearly related to radiation dose rate across four orders of magnitude. Second, there is no statistically significant difference (90% confidence limit) between the radiolytic H2 yield from pure water and that from seawater; this result rules out influence of abundant seawater salts on H2 yield from water radiolysis. Third, H2 production from a mixture of abyssal clay and seawater is 25% higher than the yield from pure water. This enhanced yield is consistent with catalysis of radiolytic H2 production by zeolite.

NOTE: Clinical application of a OneDose™ MOSFET for skin dose measurements during internal mammary chain irradiation with high dose rate brachytherapy in carcinoma of the breast

NASA Astrophysics Data System (ADS)

Kinhikar, Rajesh A.; Sharma, Pramod K.; Tambe, Chandrashekhar M.; Mahantshetty, Umesh M.; Sarin, Rajiv; Deshpande, Deepak D.; Shrivastava, Shyam K.

2006-07-01

In our earlier study, we experimentally evaluated the characteristics of a newly designed metal oxide semiconductor field effect transistor (MOSFET) OneDose™ in-vivo dosimetry system for Ir-192 (380 keV) energy and the results were compared with thermoluminescent dosimeters (TLDs). We have now extended the same study to the clinical application of this MOSFET as an in-vivo dosimetry system. The MOSFET was used during high dose rate brachytherapy (HDRBT) of internal mammary chain (IMC) irradiation for a carcinoma of the breast. The aim of this study was to measure the skin dose during IMC irradiation with a MOSFET and a TLD and compare it with the calculated dose with a treatment planning system (TPS). The skin dose was measured for ten patients. All the patients' treatment was planned on a PLATO treatment planning system. TLD measurements were performed to compare the accuracy of the measured results from the MOSFET. The mean doses measured with the MOSFET and the TLD were identical (0.5392 Gy, 15.85% of the prescribed dose). The mean dose was overestimated by the TPS and was 0.5923 Gy (17.42% of the prescribed dose). The TPS overestimated the skin dose by 9% as verified by the MOSFET and TLD. The MOSFET provides adequate in-vivo dosimetry for HDRBT. Immediate readout after irradiation, small size, permanent storage of dose and ease of use make the MOSFET a viable alternative for TLDs.

Ultralow-dose computed tomography imaging for surgery of midfacial and orbital fractures using ASIR and MBIR.

PubMed

Widmann, G; Dalla Torre, D; Hoermann, R; Schullian, P; Gassner, E M; Bale, R; Puelacher, W

2015-04-01

The influence of dose reductions on diagnostic quality using a series of high-resolution ultralow-dose computed tomography (CT) scans for computer-assisted planning and surgery including the most recent iterative reconstruction algorithms was evaluated and compared with the fracture detectability of a standard cranial emergency protocol. A human cadaver head including the mandible was artificially prepared with midfacial and orbital fractures and scanned using a 64-multislice CT scanner. The CT dose index volume (CTDIvol) and effective doses were calculated using application software. Noise was evaluated as the standard deviation in Hounsfield units within an identical region of interest in the posterior fossa. Diagnostic quality was assessed by consensus reading of a craniomaxillofacial surgeon and radiologist. Compared with the emergency protocol at CTDIvol 35.3 mGy and effective dose 3.6 mSv, low-dose protocols down to CTDIvol 1.0 mGy and 0.1 mSv (97% dose reduction) may be sufficient for the diagnosis of dislocated craniofacial fractures. Non-dislocated fractures may be detected at CTDIvol 2.6 mGy and 0.3 mSv (93% dose reduction). Adaptive statistical iterative reconstruction (ASIR) 50 and 100 reduced average noise by 30% and 56%, and model-based iterative reconstruction (MBIR) by 93%. However, the detection rate of fractures could not be improved due to smoothing effects. Crown Copyright © 2015. Published by Elsevier Ltd. All rights reserved.

Evaluation of an intragastric challenge model for Shigella dysenteriae 1 in rhesus monkeys (Macaca mulatta) for the pre-clinical assessment of Shigella vaccine formulations.

PubMed

Islam, Dilara; Ruamsap, Nattaya; Khantapura, Patchariya; Aksomboon, Ajchara; Srijan, Apichai; Wongstitwilairoong, Boonchai; Bodhidatta, Ladaporn; Gettayacamin, Montip; Venkatesan, Malabi M; Mason, Carl J

2014-06-01

Shigellosis is a worldwide disease, characterized by abdominal pain, fever, vomiting, and the passage of blood- and mucus-streaked stools. Rhesus monkeys and other primates are the only animals that are naturally susceptible to shigellosis. A suitable animal model is required for the pre-clinical evaluation of vaccines candidates. In this study, the minimal dose of Shigella dysenteriae1 1617 strain required to produce dysentery in four of five (80% attack rate) monkeys using an escalating dose range for three groups [2 × 10(8) , 2 × 10(9) and 2 × 10(10) colony forming unit (CFU)] was determined. In addition, the monkeys were re-infected. The identified optimal challenge dose was 2 × 10(9) CFU; this dose elicited 60% protection in monkeys when they were re-challenged with a one log higher dose (2 × 10(10) CFU). The challenge dose, 2 × 10(10) CFU, produced severe dysentery in all monkeys, with one monkey dying within 24 h, elicited 100% protection when re-challenged with the same dose. All monkeys exhibited immune responses. This study concludes that the rhesus monkey model closely mimics the disease and immune response seen in humans and is a suitable animal model for the pre-clinical evaluation of Shigella vaccine candidates. Prior infection with the 1617 strain can protect monkeys against subsequent re-challenges with homologous strains. © 2013 The Authors. APMIS published by John Wiley & Sons Ltd.

Evaluation of World Population-Weighted Effective Dose due to Cosmic Ray Exposure

PubMed Central

Sato, Tatsuhiko

2016-01-01

After the release of the Report of the United Nations Scientific Committee of the Effects of Atomic Radiation in 2000 (UNSCEAR2000), it became commonly accepted that the world population-weighted effective dose due to cosmic-ray exposure is 0.38 mSv, with a range from 0.3 to 2 mSv. However, these values were derived from approximate projections of altitude and geographic dependences of the cosmic-ray dose rates as well as the world population. This study hence re-evaluated the population-weighted annual effective doses and their probability densities for the entire world as well as for 230 individual nations, using a sophisticated cosmic-ray flux calculation model in tandem with detailed grid population and elevation databases. The resulting world population-weighted annual effective dose was determined to be 0.32 mSv, which is smaller than the UNSCEAR’s evaluation by 16%, with a range from 0.23 to 0.70 mSv covering 99% of the world population. These values were noted to vary with the solar modulation condition within a range of approximately 15%. All assessed population-weighted annual effective doses as well as their statistical information for each nation are provided in the supplementary files annexed to this report. These data improve our understanding of cosmic-ray radiation exposures to populations globally. PMID:27650664

Pharmacogenetic approach to losartan in Marfan patients: a starting point to improve dosing regimen?

PubMed

Falvella, Felicia Stefania; Marelli, Susan; Cheli, Stefania; Montanelli, Stefano; Viecca, Federico; Salvi, Lucia; Ferrara, Alfio; Clementi, Emilio; Trifirò, Giuliana; Pini, Alessandro

2016-09-01

Losartan is under evaluation for managing Marfan patients with aortic root dilatation. Cytochrome P450 (CYP) enzymes convert losartan to E3174 active metabolite. The aim of this study is to describe the distribution of CYP2C9*2, CYP2C9*3, CYP3A4*22 and CYP3A5*3 defective alleles, according to losartan tolerance in paediatric Marfan patients. We genotyped 53 paediatric Marfan patients treated with losartan. The rate of aortic root dilatation was evaluated using the delta z-score variation. Differences in tolerated losartan daily doses with respect to CYP metabolic classes were assessed through the Kruskal-Wallis test. The losartan daily dose spans from 0.16 to 2.50 mg/kg (median 1.10 mg/kg). As we expect from the pharmacokinetics pathway, we observe highest tolerated dose in CYP2C9 poor metabolisers (median 1.50 mg/kg, interquartile range 1.08-1.67 mg/kg); however, this difference is not statistically significant. The optimal dose of angiotensin receptor blocker is not known, and no data are available about losartan pharmacogenetic profile in Marfan syndrome; we have proposed a strategy to tackle this issue based on evaluating the major genetic polymorphisms involved in the losartan conversion into active carboxylic acid metabolite. Further studies are needed to support the use of genetic polymorphisms as predictors of the right dose of losartan.

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

Fakir, H.; Gaede, S.; Mulligan, M.

Purpose: To design a versatile, nonhomogeneous insert for the dose verification phantom ArcCHECK{sup Trade-Mark-Sign} (Sun Nuclear Corp., FL) and to demonstrate its usefulness for the verification of dose distributions in inhomogeneous media. As an example, we demonstrate it can be used clinically for routine quality assurance of two volumetric modulated arc therapy (VMAT) systems for lung stereotactic body radiation therapy (SBRT): SmartArc{sup Registered-Sign} (Pinnacle{sup 3}, Philips Radiation Oncology Systems, Fitchburg, WI) and RapidArc{sup Registered-Sign} (Eclipse{sup Trade-Mark-Sign }, Varian Medical Systems, Palo Alto, CA). Methods: The cylindrical detector array ArcCHECK{sup Trade-Mark-Sign} has a retractable homogeneous acrylic insert. In this work, wemore » designed and manufactured a customized heterogeneous insert with densities that simulate soft tissue, lung, bone, and air. The insert offers several possible heterogeneity configurations and multiple locations for point dose measurements. SmartArc{sup Registered-Sign} and RapidArc{sup Registered-Sign} plans for lung SBRT were generated and copied to ArcCHECK{sup Trade-Mark-Sign} for each inhomogeneity configuration. Dose delivery was done on a Varian 2100 ix linac. The evaluation of dose distributions was based on gamma analysis of the diode measurements and point doses measurements at different positions near the inhomogeneities. Results: The insert was successfully manufactured and tested with different measurements of VMAT plans. Dose distributions measured with the homogeneous insert showed gamma passing rates similar to our clinical results ({approx}99%) for both treatment-planning systems. Using nonhomogeneous inserts decreased the passing rates by up to 3.6% in the examples studied. Overall, SmartArc{sup Registered-Sign} plans showed better gamma passing rates for nonhomogeneous measurements. The discrepancy between calculated and measured point doses was increased up to 6.5% for the nonhomogeneous insert depending on the inhomogeneity configuration and measurement location. SmartArc{sup Registered-Sign} and RapidArc{sup Registered-Sign} plans had similar plan quality but RapidArc{sup Registered-Sign} plans had significantly higher monitor units (up to 70%). Conclusions: A versatile, nonhomogeneous insert was developed for ArcCHECK{sup Trade-Mark-Sign} for an easy and quick evaluation of dose calculations with nonhomogeneous media and for comparison of different treatment planning systems. The device was tested for SmartArc{sup Registered-Sign} and RapidArc{sup Registered-Sign} plans for lung SBRT, showing the uncertainties of dose calculations with inhomogeneities. The new insert combines the convenience of the ArcCHECK{sup Trade-Mark-Sign} and the possibility of assessing dose distributions in inhomogeneous media.« less

Adverse events following school-based vaccination of girls with quadrivalent human papillomavirus vaccine in Slovenia, 2009 to 2013.

PubMed

Šubelj, Maja; Učakar, Veronika; Kraigher, Alenka; Klavs, Irena

2016-01-01

Adverse events following immunisation (AEFIs) with qHPV reported to the Slovenian AEFI Registry for the first four school years of the vaccination programme were analysed. We calculated annual reporting rates for 11-14 year-old vaccinees with AEFIs, using the number of qHPV doses distributed within the school-based vaccination programme as the denominator. Between September 2009 and August 2013, 211 AEFIs that occurred in 89 vaccinees were reported, a rate of 149.5 vaccinees with AEFI per 100,000 qHPV doses distributed. For five vaccinees, serious AEFIs (8.4 per 100,000 doses distributed) were reported. The highest reporting rates were for fatigue, headache, and fever (≥ 38.0⁰) (53.8, 40.3, and 35.3 per 100,000 qHPV doses distributed, respectively). As no AEFI resulted in permanent sequelae and they all were categorised as serious only due to the criterion of a minimum of one day of hospitalisation, this provides reassurance for the safety of our school-based HPV vaccination programme. Further AEFI surveillance is warranted to provide data for HPV vaccination programme monitoring and evaluation of its safety.

Immunogenicity and tolerability after two doses of non-adjuvanted, whole-virion pandemic influenza A (H1N1) vaccine in HIV-infected individuals.

PubMed

Lagler, Heimo; Grabmeier-Pfistershammer, Katharina; Touzeau-Römer, Veronique; Tobudic, Selma; Ramharter, Michael; Wenisch, Judith; Gualdoni, Guido Andrés; Redlberger-Fritz, Monika; Popow-Kraupp, Theresia; Rieger, Armin; Burgmann, Heinz

2012-01-01

During the influenza pandemic of 2009/10, the whole-virion, Vero-cell-derived, inactivated, pandemic influenza A (H1N1) vaccine Celvapan® (Baxter) was used in Austria. Celvapan® is adjuvant-free and was the only such vaccine at that time in Europe. The objective of this observational, non-interventional, prospective single-center study was to evaluate the immunogenicity and tolerability of two intramuscular doses of this novel vaccine in HIV-positive individuals. A standard hemagglutination inhibition (HAI) assay was used for evaluation of the seroconversion rate and seroprotection against the pandemic H1N1 strain. In addition, H1N1-specific IgG antibodies were measured using a recently developed ELISA and compared with the HAI results. Tolerability of vaccination was evaluated up to one month after the second dose. A total of 79 HIV-infected adults with an indication for H1N1 vaccination were evaluated. At baseline, 55 of the 79 participants had an HAI titer ≥1:40 and two patients showed a positive IgG ELISA. The seroconversion rate was 31% after the first vaccination, increasing to 41% after the second; the corresponding seroprotection rates were 92% and 83% respectively. ELISA IgG levels were positive in 25% after the first vaccination and in 37% after the second. Among the participants with baseline HAI titers <1:40, 63% seroconverted. Young age was clearly associated with lower HAI titers at baseline and with higher seroconversion rates, whereas none of the seven patients >60 years of age had a baseline HAI titer <1:40 or seroconverted after vaccination. The vaccine was well tolerated. The non-adjuvanted pandemic influenza A (H1N1) vaccine was well tolerated and induced a measurable immune response in a sample of HIV-infected individuals.

Immunogenicity and Tolerability after Two Doses of Non-Adjuvanted, Whole-Virion Pandemic Influenza A (H1N1) Vaccine in HIV-Infected Individuals

PubMed Central

Lagler, Heimo; Grabmeier-Pfistershammer, Katharina; Touzeau-Römer, Veronique; Tobudic, Selma; Ramharter, Michael; Wenisch, Judith; Gualdoni, Guido Andrés; Redlberger-Fritz, Monika; Popow-Kraupp, Theresia; Rieger, Armin; Burgmann, Heinz

2012-01-01

Background During the influenza pandemic of 2009/10, the whole-virion, Vero-cell-derived, inactivated, pandemic influenza A (H1N1) vaccine Celvapan® (Baxter) was used in Austria. Celvapan® is adjuvant-free and was the only such vaccine at that time in Europe. The objective of this observational, non-interventional, prospective single-center study was to evaluate the immunogenicity and tolerability of two intramuscular doses of this novel vaccine in HIV-positive individuals. Methods and Findings A standard hemagglutination inhibition (HAI) assay was used for evaluation of the seroconversion rate and seroprotection against the pandemic H1N1 strain. In addition, H1N1-specific IgG antibodies were measured using a recently developed ELISA and compared with the HAI results. Tolerability of vaccination was evaluated up to one month after the second dose. A total of 79 HIV-infected adults with an indication for H1N1 vaccination were evaluated. At baseline, 55 of the 79 participants had an HAI titer ≥1∶40 and two patients showed a positive IgG ELISA. The seroconversion rate was 31% after the first vaccination, increasing to 41% after the second; the corresponding seroprotection rates were 92% and 83% respectively. ELISA IgG levels were positive in 25% after the first vaccination and in 37% after the second. Among the participants with baseline HAI titers <1∶40, 63% seroconverted. Young age was clearly associated with lower HAI titers at baseline and with higher seroconversion rates, whereas none of the seven patients >60 years of age had a baseline HAI titer <1∶40 or seroconverted after vaccination. The vaccine was well tolerated. Conclusion The non-adjuvanted pandemic influenza A (H1N1) vaccine was well tolerated and induced a measurable immune response in a sample of HIV-infected individuals. PMID:22629330

Dose rate in brachytherapy using after-loading machine: pulsed or high-dose rate?

PubMed

Hannoun-Lévi, J-M; Peiffert, D

2014-10-01

Since February 2014, it is no longer possible to use low-dose rate 192 iridium wires due to the end of industrial production of IRF1 and IRF2 sources. The Brachytherapy Group of the French society of radiation oncology (GC-SFRO) has recommended switching from iridium wires to after-loading machines. Two types of after-loading machines are currently available, based on the dose rate used: pulsed-dose rate or high-dose rate. In this article, we propose a comparative analysis between pulsed-dose rate and high-dose rate brachytherapy, based on biological, technological, organizational and financial considerations. Copyright © 2014 Société française de radiothérapie oncologique (SFRO). Published by Elsevier SAS. All rights reserved.

Randomized controlled trial of relaxation music to reduce heart rate in patients undergoing cardiac CT.

PubMed

Ng, Ming Yen; Karimzad, Yasser; Menezes, Ravi J; Wintersperger, Bernd J; Li, Qin; Forero, Julian; Paul, Narinder S; Nguyen, Elsie T

2016-10-01

To evaluate the heart rate lowering effect of relaxation music in patients undergoing coronary CT angiography (CCTA), pulmonary vein CT (PVCT) and coronary calcium score CT (CCS). Patients were randomised to a control group (i.e. standard of care protocol) or to a relaxation music group (ie. standard of care protocol with music). The groups were compared for heart rate, radiation dose, image quality and dose of IV metoprolol. Both groups completed State-Trait Anxiety Inventory anxiety questionnaires to assess patient experience. One hundred and ninety-seven patients were recruited (61.9 % males); mean age 56y (19-86 y); 127 CCTA, 17 PVCT, 53 CCS. No significant difference in heart rate, radiation dose, image quality, metoprolol dose and anxiety scores. 86 % of patients enjoyed the music. 90 % of patients in the music group expressed a strong preference to have music for future examinations. The patient cohort demonstrated low anxiety levels prior to CT. Relaxation music in CCTA, PVCT and CCS does not reduce heart rate or IV metoprolol use. Patients showed low levels of anxiety indicating that anxiolytics may not have a significant role in lowering heart rate. Music can be used in cardiac CT to improve patient experience. • Relaxation music does not reduce heart rate in cardiac CT • Relaxation music does not reduce beta-blocker use in cardiac CT • Relaxation music has no effect on cardiac CT image quality • Low levels of anxiety are present in patients prior to cardiac CT • Patients enjoyed the relaxation music and this results in improved patient experience.

Assessing dose rate distributions in VMAT plans

NASA Astrophysics Data System (ADS)

Mackeprang, P.-H.; Volken, W.; Terribilini, D.; Frauchiger, D.; Zaugg, K.; Aebersold, D. M.; Fix, M. K.; Manser, P.

2016-04-01

Dose rate is an essential factor in radiobiology. As modern radiotherapy delivery techniques such as volumetric modulated arc therapy (VMAT) introduce dynamic modulation of the dose rate, it is important to assess the changes in dose rate. Both the rate of monitor units per minute (MU rate) and collimation are varied over the course of a fraction, leading to different dose rates in every voxel of the calculation volume at any point in time during dose delivery. Given the radiotherapy plan and machine specific limitations, a VMAT treatment plan can be split into arc sectors between Digital Imaging and Communications in Medicine control points (CPs) of constant and known MU rate. By calculating dose distributions in each of these arc sectors independently and multiplying them with the MU rate, the dose rate in every single voxel at every time point during the fraction can be calculated. Independently calculated and then summed dose distributions per arc sector were compared to the whole arc dose calculation for validation. Dose measurements and video analysis were performed to validate the calculated datasets. A clinical head and neck, cranial and liver case were analyzed using the tool developed. Measurement validation of synthetic test cases showed linac agreement to precalculated arc sector times within  ±0.4 s and doses  ±0.1 MU (one standard deviation). Two methods for the visualization of dose rate datasets were developed: the first method plots a two-dimensional (2D) histogram of the number of voxels receiving a given dose rate over the course of the arc treatment delivery. In similarity to treatment planning system display of dose, the second method displays the dose rate as color wash on top of the corresponding computed tomography image, allowing the user to scroll through the variation over time. Examining clinical cases showed dose rates spread over a continuous spectrum, with mean dose rates hardly exceeding 100 cGy min-1 for conventional fractionation. A tool to analyze dose rate distributions in VMAT plans with sub-second accuracy was successfully developed and validated. Dose rates encountered in clinical VMAT test cases show a continuous spectrum with a mean less than or near 100 cGy min-1 for conventional fractionation.

Oral Tranexamic Acid Reduces Transfusions in Total Knee Arthroplasty.

PubMed

Perreault, Roger E; Fournier, Christine A; Mattingly, David A; Junghans, Richard P; Talmo, Carl T

2017-10-01

Tranexamic acid (TXA) reduces intraoperative blood loss and transfusions in patients undergoing total knee arthroplasty. Although numerous studies demonstrate the efficacy of intravenous and topical TXA in these patients, few demonstrate the effectiveness and appropriate dosing recommendations of oral formulations. A retrospective cohort study was performed to evaluate differences in transfusion requirements in patients undergoing primary unilateral total knee arthroplasty with either no TXA (n = 866), a single-dose of oral TXA (n = 157), or both preoperative and postoperative oral TXA (n = 1049). Secondary outcomes included postoperative hemoglobin drop, total units transfused, length of stay, drain output, and cell salvage volume. Transfusion rates decreased from 15.4% in the no-oral tranexamic acid (OTA) group to 9.6% in the single-dose OTA group (P < .001) and 7% in the 2-dose group (P < .001), with no difference in transfusion rates between the single- and 2-dose groups (P = .390). In addition, postoperative hemoglobin drop was reduced from 4.2 g/dL in the no-OTA group to 3.5 g/dL in the single-dose group (P < .01) and to 3.4 g/dL in the 2-dose group (P < .01), without a difference between the single- and 2-dose groups (P = .233). OTA reduces transfusions, with greater ease of administration and improved cost-effectiveness relative to other forms of delivery. Copyright © 2017 Elsevier Inc. All rights reserved.

Radon survey and soil gamma doses in primary schools of Batman, Turkey.

PubMed

Damla, Nevzat; Aldemir, Kamuran

2014-06-01

A survey was conducted to evaluate levels of indoor radon and gamma doses in 42 primary schools located in Batman, southeastern Anatolia, Turkey. Indoor radon measurements were carried out using CR-39 solid-state nuclear track detector-based radon dosimeters. The overall mean annual (222)Rn activity in the surveyed area was found to be 49 Bq m(-3) (equivalent to an annual effective dose of 0.25 mSv). However, in one of the districts (Besiri) the maximum radon value turned out to be 307 Bq m(-3). The estimated annual effective doses are less than the recommended action level (3-10 mSv). It is found that the radon concentration decreases with increasing floor number. The concentrations of natural and artificial radioisotopes were determined using gamma-ray spectroscopy for soil samples collected in close vicinity of the studied schools. The mean gamma activity concentrations in the soil samples were 31, 25, 329 and 12 Bq kg(-1) for (226)Ra, (232)Th, (40)K and (137)Cs, respectively. The radiological parameters such as the absorbed dose rate in air and the annual effective dose equivalent were calculated. These radiological parameters were evaluated and compared with the internationally recommended values.

Sanitation of chicken eggs by ionizing radiation: functional and nutritional assessment

NASA Astrophysics Data System (ADS)

Pinto, P.; Ribeiro, R.; Sousa, L.; Verde, S. Cabo; Lima, M. G.; Dinis, M.; Santana, A.; Botelho, M. L.

2004-09-01

Alternative technologies must be developed and implemented considering sanitation and preservation of eggs mainly for risk population. Food irradiation is an alternative to free Salmonella spp. and Campylobacter spp. eggs, as a low dose point to a safety assurance. This study presents the correlation between irradiation doses (0.5 kGy up to 5 kGy at dose rate of 1.0 kGy/h) and some of functional and nutritional egg properties. Viscosimetry of non-irradiated and irradiated eggs was evaluated by means of VT550 Haake with an NV sensor and co-axes cylinders. After irradiation at 5 kGy, the yolk colour die (pale yellow) and the white egg was modified to a turbid yellow. The Cross equation was utilized to viscosimetry curves. Based on the assymptotics viscosimetry data indicated that increase of doses corresponds to an increase of the yolk and a decrease of white egg viscosimetry as such a Newton behaviour. Irradiation effects on nutritional properties were evaluated by means of egg protein patterns that were assessed by polyacrylamide gel electrophoresis. Lipids were identified by TLC. Based on results the sanitation dose is lower than the limit dose for the decrease of the main eggs properties.

Effect of gamma irradiation on the thiamine, riboflavin and vitamin B 6 content in two varieties of Brazilian beans

NASA Astrophysics Data System (ADS)

Villavicencio, A. L. C. H. A. L. C. H.; Mancini-Filho, J. J.; Delincée, H. H.; Bognár, A. A.

2000-03-01

The effect of 60Co gamma rays on the content of several B-vitamins in two varieties of Brazilian beans has been studied. Carioca ( Phaseolus vulgaris L. var. Carioca) and Macaçar beans ( Vigna unguiculata L. Walp, var. Macaçar) were irradiated at doses of 0, 0.5, 1.0, 2.5, 5.0 and 10 kGy, and subsequently stored at ambient temperature for 6 months. The content of vitamin B 1, B 2 and B 6 was analysed by HPLC. In addition, the optimum cooking time was established for each dose and bean variety. A taste panel evaluated sensory properties. Only slight changes were measured for thiamine and riboflavin, whereas a dose-dependent decrease was noted for pyridoxine, which, however, was significant only at the highest doses of 5 and 10 kGy. Cooking time was considerably reduced with increasing radiation dose, but accompanied by a loss of the sensory quality. However, at the disinfestation dose up to 1 kGy, acceptable ratings were obtained for the sensory evaluation. In conclusion, for insect disinfestation of Brazilian beans radiation processing is a promising technology.

Evaluation of the 2-(1-Hexyloxyethyl)-2-devinyl pyropheophorbide (HPPH) mediated photodynamic therapy by macroscopic singlet oxygen modeling.

PubMed

Penjweini, Rozhin; Kim, Michele M; Liu, Baochang; Zhu, Timothy C

2016-12-01

Photodynamic therapy (PDT) is known as a non-invasive treatment modality that is based on photochemical reactions between oxygen, photosensitizer, and a special wavelength of light. However, a dosimetric predictor for PDT outcome is still elusive because current dosimetric quantities do not account for the differences in the PDT oxygen consumption rate for different fluence rates. In this study, we evaluate several dose metrics, total fluence, photobleaching ratio, PDT dose, and mean reacted singlet oxygen (mean [ 1 O 2 ] rx ) for predicting the PDT outcome and a clinically relevant tumor re-growth endpoint. For this reason, radiation-induced fibrosarcoma (RIF) mice tumors are treated with 2-(1-Hexyloxyethyl)-2-devinyl pyropheophorbide (HPPH) and different in-air fluences (30 J/cm 2 , 50 J/cm 2 , 135 J/cm 2 , 250 J/cm 2 , and 350 J/cm 2 ) and in-air fluence rates (20, 50, 75, 150 mW/cm 2 ). Explicit measurements of HPPH and oxygen concentration as well as tissue optical properties are performed pre- and post-treatment. Then, this information is incorporated into a macroscopic model to calculate the photobleaching, PDT dose, and mean [ 1 O 2 ] rx . Changes in tumor volume are tracked following the treatment and compared with the dose metrics. The correlation demonstrates that mean [ 1 O 2 ] rx  serves as a better dosimetric quantity for predicting treatment outcome and a clinically relevant tumor re-growth endpoint. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A novel design for a dose finding, safety, and drug interaction study of an antiepileptic drug (retigabine) in early clinical development.

PubMed

Sachdeo, Rajesh; Partiot, Arnaud; Biton, Victor; Rosenfeld, William E; Nohria, Virinder; Tompson, Debra; DeRossett, Sarah; Porter, Roger J

2014-06-01

To obtain information on the acceptable doses of the antiepileptic drug (AED) retigabine (RTG), the maximum tolerated dose (MTD), drug interactions, safety and tolerability, and preliminary evidence of efficacy when administered as adjunctive therapy and as monotherapy. Study 202 was an open-label, add-on study in patients with partial or generalized epilepsy treated with valproic acid (VPA), carbamazepine (CBZ), phenytoin (PHT), or topiramate (TPM) as monotherapy. Following baseline assessments, patients entered a dose titration phase of 28 – 56 days. The initial daily RTG dose was 100 or 200 mg (2 or 3 × daily). The RTG dose was increased every 1 - 2 weeks by 50 - 200 mg to a maximum of 1,600 mg/day. Once the RTG MTD had been attained, patients entered a 14-day maintenance period. Following this, the patient's background AED dose could be reduced, with the possibility of achieving RTG monotherapy. The final dosing regimen attained was maintained for an additional 14 days. Patients who completed study 202 could choose to continue treatment with RTG (with or without other AEDs) in study 208, the long-term extension of study 202. Safety assessments included adverse event (AE) monitoring, clinical laboratory evaluations, electrocardiograms, and physical and neurologic examinations. Patients' seizure diaries to assess the frequency and type of seizures, the percentage change in seizure rate, and the responder rate (>= 50% reduction in seizure rate from baseline) were evaluated. 60 patients (mean age 37.2, range 16 - 64 years) were enrolled in study 202, and 47 (78%) continued treatment with RTG in the extension study (208). In study 202, the most commonly reported AEs were: dizziness (53%), asthenia (42%), somnolence (33%), nausea (27%), speech disorder (27%), and tremor (27%). In the extension study, AEs were similar and included dizziness, somnolence, diplopia, feeling "drunk", confusion, fatigue, and dysarthria. The median percent reductions in 28-day seizure rate, relative to baseline in Studies 202 and 208, were ~ 20% and 47%, respectively. RTG did not alter the pharmacokinetics of the four monotherapy AEDs investigated. CBZ and PHT increased RTG clearance by 27% and 36%, respectively, whereas TPM and VPA had no effect on RTG clearance. Studies 202 and 208 provided critical information on RTG safety and tolerability, and reductions in seizure rates towards the design and conduct of subsequent pivotal clinical trials. Likewise, information regarding the appropriate dosage of RTG with VPA, CBZ, PHT, or TPM was obtained, which permitted the subsequent pivotal trials to be performed appropriately. *Currently at Shire Pharmaceuticals, Behavioral Health Business Unit, Wayne, PA, USA **Currently at University of Pennsylvania, Department of Neurology, Philadelphia, PA, USA.

Dosimetric validation for an automatic brain metastases planning software using single-isocenter dynamic conformal arcsDosimetric validation for an automatic brain metastases planning software using single-isocenter dynamic conformal arcs.

PubMed

Liu, Haisong; Li, Jun; Pappas, Evangelos; Andrews, David; Evans, James; Werner-Wasik, Maria; Yu, Yan; Dicker, Adam; Shi, Wenyin

2016-09-08

An automatic brain-metastases planning (ABMP) software has been installed in our institution. It is dedicated for treating multiple brain metastases with radiosurgery on linear accelerators (linacs) using a single-setup isocenter with noncoplanar dynamic conformal arcs. This study is to validate the calculated absolute dose and dose distribution of ABMP. Three types of measurements were performed to validate the planning software: 1, dual micro ion chambers were used with an acrylic phantom to measure the absolute dose; 2, a 3D cylindrical phantom with dual diode array was used to evaluate 2D dose distribution and point dose for smaller targets; and 3, a 3D pseudo-in vivo patient-specific phantom filled with polymer gels was used to evaluate the accuracy of 3D dose distribution and radia-tion delivery. Micro chamber measurement of two targets (volumes of 1.2 cc and 0.9 cc, respectively) showed that the percentage differences of the absolute dose at both targets were less than 1%. Averaged GI passing rate of five different plans measured with the diode array phantom was above 98%, using criteria of 3% dose difference, 1 mm distance to agreement (DTA), and 10% low-dose threshold. 3D gel phantom measurement results demonstrated a 3D displacement of nine targets of 0.7 ± 0.4 mm (range 0.2 ~ 1.1 mm). The averaged two-dimensional (2D) GI passing rate for several region of interests (ROI) on axial slices that encompass each one of the nine targets was above 98% (5% dose difference, 2 mm DTA, and 10% low-dose threshold). Measured D95, the minimum dose that covers 95% of the target volume, of the nine targets was 0.7% less than the calculated D95. Three different types of dosimetric verification methods were used and proved the dose calculation of the new automatic brain metastases planning (ABMP) software was clinical acceptable. The 3D pseudo-in vivo patient-specific gel phantom test also served as an end-to-end test for validating not only the dose calculation, but the treatment delivery accuracy as well. © 2016 The Authors.

Psilocybin occasioned mystical-type experiences: immediate and persisting dose-related effects.

PubMed

Griffiths, Roland R; Johnson, Matthew W; Richards, William A; Richards, Brian D; McCann, Una; Jesse, Robert

2011-12-01

This dose-effect study extends previous observations showing that psilocybin can occasion mystical-type experiences having persisting positive effects on attitudes, mood, and behavior. This double-blind study evaluated psilocybin (0, 5, 10, 20, 30 mg/70 kg, p.o.) administered under supportive conditions. Participants were 18 adults (17 hallucinogen-naïve). Five 8-h sessions were conducted individually for each participant at 1-month intervals. Participants were randomized to receive the four active doses in either ascending or descending order (nine participants each). Placebo was scheduled quasi-randomly. During sessions, volunteers used eyeshades and were instructed to direct their attention inward. Volunteers completed questionnaires assessing effects immediately after and 1 month after each session, and at 14 months follow-up. Psilocybin produced acute perceptual and subjective effects including, at 20 and/or 30 mg/70 kg, extreme anxiety/fear (39% of volunteers) and/or mystical-type experience (72% of volunteers). One month after sessions at the two highest doses, volunteers rated the psilocybin experience as having substantial personal and spiritual significance, and attributed to the experience sustained positive changes in attitudes, mood, and behavior, with the ascending dose sequence showing greater positive effects. At 14 months, ratings were undiminished and were consistent with changes rated by community observers. Both the acute and persisting effects of psilocybin were generally a monotonically increasing function of dose, with the lowest dose showing significant effects. Under supportive conditions, 20 and 30 mg/70 kg psilocybin occasioned mystical-type experiences having persisting positive effects on attitudes, mood, and behavior. Implications for therapeutic trials are discussed.

Verification of shielding effect by the water-filled materials for space radiation in the International Space Station using passive dosimeters

NASA Astrophysics Data System (ADS)

Kodaira, S.; Tolochek, R. V.; Ambrozova, I.; Kawashima, H.; Yasuda, N.; Kurano, M.; Kitamura, H.; Uchihori, Y.; Kobayashi, I.; Hakamada, H.; Suzuki, A.; Kartsev, I. S.; Yarmanova, E. N.; Nikolaev, I. V.; Shurshakov, V. A.

2014-01-01

The dose reduction effects for space radiation by installation of water shielding material ("protective curtain") of a stack board consisting of the hygienic wipes and towels have been experimentally evaluated in the International Space Station by using passive dosimeters. The averaged water thickness of the protective curtain was 6.3 g/cm2. The passive dosimeters consisted of a combination of thermoluminescent detectors (TLDs) and plastic nuclear track detectors (PNTDs). Totally 12 passive dosimeter packages were installed in the Russian Service Module during late 2010. Half of the packages were located at the protective curtain surface and the other half were at the crew cabin wall behind or aside the protective curtain. The mean absorbed dose and dose equivalent rates are measured to be 327 μGy/day and 821 μSv/day for the unprotected packages and 224 μGy/day and 575 μSv/day for the protected packages, respectively. The observed dose reduction rate with protective curtain was found to be 37 ± 7% in dose equivalent, which was consistent with the calculation in the spherical water phantom by PHITS. The contributions due to low and high LET particles were found to be comparable in observed dose reduction rate. The protective curtain would be effective shielding material for not only trapped particles (several 10 MeV) but also for low energy galactic cosmic rays (several 100 MeV/n). The properly utilized protective curtain will effectively reduce the radiation dose for crew living in space station and prolong long-term mission in the future.

External beam radiotherapy for palliation of painful bone metastases: pooled data bioeffect dose response analysis of dose fractionation

NASA Astrophysics Data System (ADS)

Naveen, T.; Supe, Sanjay S.; Ganesh, K. M.; Samuel, Jacob

2009-01-01

Bone metastases develop in up to 70% of newly diagnosed cancer patients and result in immobility, anxiety, and depression, severely diminishing the patients quality of life. Radiotherapy is a frequently used modality for bone metastasis and has been shown to be effective in reducing metastatic bone pain and in some instances, causing tumor shrinkage or growth inhibition. There is controversy surrounding the optimal fractionation schedule and total dose of external beam radiotherapy, despite many randomized trials and overviews addressing the issue. This study was undertaken to apply BED to clinical fractionation data of radiotherapeutic management of bone metastases in order to arrive at optimum BED values for acceptable level of response rate. A computerised literature search was conducted to identify all prospective clinical studies that addressed the issue of fractionation for the treatment of bone metastasis. The results of these studies were pooled together to form the database for the analysis. A total of 4111 number of patients received radiation dose ranging from 4 to 40.5 Gy in 1 to 15 fractions with dose per fraction ranging from 2 to 10 Gy. Single fraction treatments were delivered in 2013 patients and the dose varied from 4 to 10 Gy. Multifraction treatments were delivered in 2098 patients and the dose varied from 15 to 40.5 Gy. The biological effective dose (BED) was evaluated for each fractionation schedule using the linear quadratic model and an α/β value of 10 Gy. Response rate increased significantly beyond a BED value of 14.4 Gy (p < 0.01). Based on our analysis and indications from the literature about higher retreatment and fracture rate of single fraction treatments, minimum BED value of 14.4 Gy is recommended.

Optimal dose and volume for postoperative radiotherapy in brain oligometastases from lung cancer: a retrospective study.

PubMed

Chung, Seung Yeun; Chang, Jong Hee; Kim, Hye Ryun; Cho, Byoung Chul; Lee, Chang Geol; Suh, Chang-Ok

2017-06-01

To evaluate intracranial control after surgical resection according to the adjuvant treatment received in order to assess the optimal radiotherapy (RT) dose and volume. Between 2003 and 2015, a total of 53 patients with brain oligometastases from non-small cell lung cancer (NSCLC) underwent metastasectomy. The patients were divided into three groups according to the adjuvant treatment received: whole brain radiotherapy (WBRT) ± boost (WBRT ± boost group, n = 26), local RT/Gamma Knife surgery (local RT group, n = 14), and the observation group (n = 13). The most commonly used dose schedule was WBRT (25 Gy in 10 fractions, equivalent dose in 2 Gy fractions [EQD2] 26.04 Gy) with tumor bed boost (15 Gy in 5 fractions, EQD2 16.25 Gy). The WBRT ± boost group showed the lowest 1-year intracranial recurrence rate of 30.4%, followed by the local RT and observation groups, at 66.7%, and 76.9%, respectively (p = 0.006). In the WBRT ± boost group, there was no significant increase in the 1-year new site recurrence rate of patients receiving a lower dose of WBRT (EQD2) <27 Gy compared to that in patients receiving a higher WBRT dose (p = 0.553). The 1-year initial tumor site recurrence rate was lower in patients receiving tumor bed dose (EQD2) of ≥42.3 Gy compared to those receiving <42.3 Gy, although the difference was not significant (p = 0.347). Adding WBRT after resection of brain oligometastases from NSCLC seems to enhance intracranial control. Furthermore, combining lower-dose WBRT with a tumor bed boost may be an attractive option.

Optimal dose and volume for postoperative radiotherapy in brain oligometastases from lung cancer: a retrospective study

PubMed Central

Chung, Seung Yeun; Chang, Jong Hee; Kim, Hye Ryun; Cho, Byoung Chul; Lee, Chang Geol; Suh, Chang-Ok

2017-01-01

Purpose To evaluate intracranial control after surgical resection according to the adjuvant treatment received in order to assess the optimal radiotherapy (RT) dose and volume. Materials and Methods Between 2003 and 2015, a total of 53 patients with brain oligometastases from non-small cell lung cancer (NSCLC) underwent metastasectomy. The patients were divided into three groups according to the adjuvant treatment received: whole brain radiotherapy (WBRT) ± boost (WBRT ± boost group, n = 26), local RT/Gamma Knife surgery (local RT group, n = 14), and the observation group (n = 13). The most commonly used dose schedule was WBRT (25 Gy in 10 fractions, equivalent dose in 2 Gy fractions [EQD2] 26.04 Gy) with tumor bed boost (15 Gy in 5 fractions, EQD2 16.25 Gy). Results The WBRT ± boost group showed the lowest 1-year intracranial recurrence rate of 30.4%, followed by the local RT and observation groups, at 66.7%, and 76.9%, respectively (p = 0.006). In the WBRT ± boost group, there was no significant increase in the 1-year new site recurrence rate of patients receiving a lower dose of WBRT (EQD2) <27 Gy compared to that in patients receiving a higher WBRT dose (p = 0.553). The 1-year initial tumor site recurrence rate was lower in patients receiving tumor bed dose (EQD2) of ≥42.3 Gy compared to those receiving <42.3 Gy, although the difference was not significant (p = 0.347). conclusions Adding WBRT after resection of brain oligometastases from NSCLC seems to enhance intracranial control. Furthermore, combining lower-dose WBRT with a tumor bed boost may be an attractive option. PMID:28712276

Radiation concurrent with gemcitabine for locally advanced head and neck cancer: a phase I trial and intracellular drug incorporation study.

PubMed

Eisbruch, A; Shewach, D S; Bradford, C R; Littles, J F; Teknos, T N; Chepeha, D B; Marentette, L J; Terrell, J E; Hogikyan, N D; Dawson, L A; Urba, S; Wolf, G T; Lawrence, T S

2001-02-01

To examine the feasibility and dose-limiting toxicity (DLT) of once-weekly gemcitabine at doses predicted in preclinical studies to produce radiosensitization, concurrent with a standard course of radiation for locally advanced head and neck cancer. Tumor incorporation of gemcitabine triphosphate (dFdCTP) was measured to assess whether adequate concentrations were achieved at each dose level. Twenty-nine patients with unresectable head and neck cancer received a course of radiation (70 Gy over 7 weeks, 5 days weekly) concurrent with weekly infusions of low-dose gemcitabine. Tumor biopsies were performed after the first gemcitabine infusion (before radiation started), and the intracellular concentrations of dFdCTP were measured. Severe acute and late mucosal and pharyngeal-related DLT required de-escalation of gemcitabine dose in successive patient cohorts receiving dose levels of 300 mg/m(2)/wk, 150 mg/m(2)/wk, and 50 mg/m(2)/wk. No DLT was observed at 10 mg/m(2)/wk. The rate of endoscopy- and biopsy-assessed complete tumor response was 66% to 87% in the various cohorts. Tumor dFdCTP levels were similar in patients receiving 50 to 300 mg/m(2) (on average, 1.55 pmol/mg, SD 1.15) but were barely or not detectable at 10 mg/m(2). A high rate of acute and late mucosa-related DLT and a high rate of complete tumor response were observed in this regimen at the dose levels of 50 to 300 mg/m(2), which also resulted in similar, subcytotoxic intracellular dFdCTP concentrations. These results demonstrate significant tumor and normal tissue radiosensitization by low-dose gemcitabine. Different regimens of combined radiation and gemcitabine should be evaluated, based on newer preclinical data promising an improved therapeutic ratio.

Retrospective cross-sectional pilot study of rifaximin dosing for the prevention of recurrent hepatic encephalopathy.

PubMed

Lyon, Kelsey C; Likar, Eric; Martello, Jay L; Regier, Michael

2017-09-01

Standard treatment for hepatic encephalopathy (HE) includes medications that reduce ammonia and bacterial translocation in the gut. Rifaximin can be used off-label for the reduction of overt HE. The study purpose was to determine efficacy of traditional rifaximin dosing (400 mg three times daily) compared with newer dosing (550 mg twice daily) via readmission rates for the prevention of recurrent HE. This was a retrospective, observational, cross-sectional pilot study conducted in a tertiary medical center. A total of 226 patients 18-89 years of age with documentation of HE via ICD-9 code who started rifaximin therapy while inpatient between April 2009 and June 2014 were evaluated. Data collected included rifaximin dosing, other medications used to treat HE, duration of therapy, time to readmission, and various laboratory values. There were no differences in readmission rates at 30 days, 60 days, or 6 months between treatment groups. Additionally, there was no difference in the odds of readmission between the treatment groups (OR = 0.77, 95% CI: [0.201, 4.365], P = 0.718). Patients had a low overall probability of readmission over the observational period. Based on average wholesale price data, the cost for a 9-day supply of rifaximin for the 400-mg dosing regimen is $952.56 versus $605.16 for the 550-mg dosing regimen. The rifaximin 550-mg dosing strategy should be utilized in hospitalized patients for the prevention of recurrent HE as there was no difference in readmission rate or time to readmission between dosing groups. The 550-mg regimen had a lower acquisition cost for a 9-day duration of treatment in the studied institution. © 2017 Journal of Gastroenterology and Hepatology Foundation and John Wiley & Sons Australia, Ltd.

Effects of topical combinations of clonidine and pentoxifylline on capsaicin-induced allodynia and postcapsaicin tourniquet-induced pain in healthy volunteers: a double-blind, randomized, controlled study.

PubMed

Ragavendran, J Vaigunda; Laferrière, André; Bennett, Gary J; Ware, Mark A; Gandhi, Wiebke; Bley, Keith; Schweinhardt, Petra; Coderre, Terence J

2016-10-01

This double-blind randomized controlled study was designed to evaluate the analgesic effects of topical treatments with clonidine (CLON) and pentoxifylline (PTX) tested alone or as low- and high-dose combinations in a human experimental model of pain. Of 69 healthy subjects aged 18 to 60 years, 23 each were randomly allocated to low-dose (0.04% + 2%) and high-dose (0.1% + 5%) CLON + PTX groups. Both of these groups also received their corresponding placebos in one of 2 treatment periods separated by at least 48 hours. Twenty-three additional subjects received either CLON (0.1%) or PTX (5%) as single drug treatments, in each of 2 treatment periods. Assessment of analgesic efficacy was based on allodynic effects of previous intraepidermal capsaicin injection, as well as postcapsaicin tourniquet-induced pain 50 minutes following capsaicin injection. Visual Analogue Scale (VAS) ratings of pain intensity and the area of dynamic mechanical allodynia were the primary outcome measures, whereas area of punctate mechanical allodynia (PMA) served as a secondary outcome measure. Topical treatments with high- or low-dose combinations significantly reduced VAS ratings compared with corresponding placebo treatments throughout the period of postcapsaicin tourniquet-induced pain. Importantly, the high-dose combination produced lower VAS ratings than CLON alone, which were lower than PTX alone. Results also revealed significant inhibition of postcapsaicin dynamic mechanical allodynia and PMA for the high-dose combination compared with placebo, and of PMA for CLON compared with the low-dose combination. Hence, the present data are supportive of further clinical investigation of the high-dose topical combination of CLON + PTX in complex regional pain syndrome and neuropathic pain patients, for which our preclinical data predict efficacy.

Parenteral cidofovir for cytomegalovirus retinitis in patients with AIDS: the HPMPC peripheral cytomegalovirus retinitis trial. A randomized, controlled trial. Studies of Ocular complications of AIDS Research Group in Collaboration with the AIDS Clinical Trials Group.

PubMed

1997-02-15

Cytomegalovirus (CMV) retinitis is a common infection and a major cause of visual loss in patients with the acquired immunodeficiency syndrome (AIDS). To evaluate intravenous cidofovir as a treatment for CMV retinitis. Two-stage, multicenter, phase II/III, randomized, controlled clinical trial. Ophthalmology and AIDS services at tertiary care medical centers. 64 patients with AIDS and previously untreated, small, peripheral CMV retinitis lesions (that is, patients at low risk for loss of visual acuity). Patients were randomly assigned to one of three groups: the deferral group, in which treatment was deferred until retinitis progressed; the low-dose cidofovir group, which received cidofovir, 5 mg/kg of body weight once weekly for 2 weeks, then maintenance therapy with cidofovir, 3 mg/kg once every 2 weeks; or the high-dose cidofovir group, which received cidofovir, 5 mg/kg once weekly for 2 weeks, then maintenance therapy with cidofovir, 5 mg/kg once every 2 weeks. To minimize nephrotoxicity, cidofovir was administered with hydration and probenecid. Progression of retinitis, evaluated in a masked manner by a fundus photograph reading center; the amount of retinal area involved by CMV; the loss of visual acuity; and morbidity. Median time to progression was 64 days in the low-dose cidofovir group and 21 days in the deferral group (P = 0.052, log-rank test). The median time to progression was not reached in the high-dose cidofovir group but was 20 days in the deferral group (P = 0.009, log-rank test). Analysis of the rates of increase in the retinal area affected by CMV confirmed the data on time to progression. The three groups had similar rates of visual loss. Proteinuria of 2+ or more occurred at rates of 2.6 per person-year in the deferral group, 2.8 per person-year in the low-dose cidofovir group (P > 0.02), and 6.8 per person-year in the high-dose cidofovir group (P = 0.135). No patient developed 4+ proteinuria, but two cidofovir recipients developed persistent elevations of serum creatinine levels at more than 177 mumol/L (2.0 mg/dL). Reactions to probenecid occurred at a rate of 0.70 per person-year. Intravenous cidofovir, high- or low-dose, effectively slowed the progression of CMV retinitis. Concomitant probenecid and hydration therapy, intermittent dosing, and monitoring for proteinuria seemed to minimize but not eliminate the risk for nephrotoxicity.

A PILOT STUDY USING AN ACCELEROMETER TO EVALUATE A CAREGIVER'S INTERPRETATION OF AN INFANT OR TODDLER'S ACTIVITY LEVEL AS RECORDED IN A TIME ACTIVITY DIARY

EPA Science Inventory

Linking a young child's activity pattern data with samples that are collected during an exposure assessment is important in evaluating uptake dose rates associated with environmental contaminant exposures. A pilot study (N=9) was performed to test how well categorical activity-le...

Characterization of a Cynomolgus Macaque Model of Pneumonic Plague for Evaluation of Vaccine Efficacy.

PubMed

Fellows, Patricia; Price, Jessica; Martin, Shannon; Metcalfe, Karen; Krile, Robert; Barnewall, Roy; Hart, Mary Kate; Lockman, Hank

2015-09-01

The efficacy of a recombinant plague vaccine (rF1V) was evaluated in cynomolgus macaques (CMs) to establish the relationship among vaccine doses, antibody titers, and survival following an aerosol challenge with a lethal dose of Yersinia pestis strain Colorado 92. CMs were vaccinated with a range of rF1V doses on a three-dose schedule (days 0, 56, and 121) to provide a range of survival outcomes. The humoral immune response following vaccination was evaluated with anti-rF1, anti-rV, and anti-rF1V bridge enzyme-linked immunosorbent assays (ELISAs). Animals were challenged via aerosol exposure on day 149. Vaccine doses and antibody responses were each significantly associated with the probability of CM survival (P < 0.0001). Vaccination also decreased signs of pneumonic plague in a dose-dependent manner. There were statistically significant correlations between the vaccine dose and the time to onset of fever (P < 0.0001), the time from onset of fever to death (P < 0.0001), the time to onset of elevated respiratory rate (P = 0.0003), and the time to onset of decreased activity (P = 0.0251) postinfection in animals exhibiting these clinical signs. Delays in the onset of these clinical signs of disease were associated with larger doses of rF1V. Immunization with ≥ 12 μg of rF1V resulted in 100% CM survival. Since both the vaccine dose and anti-rF1V antibody titers correlate with survival, rF1V bridge ELISA titers can be used as a correlate of protection. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Dosimetric verification of stereotactic radiosurgery/stereotactic radiotherapy dose distributions using Gafchromic EBT3.

PubMed

Cusumano, Davide; Fumagalli, Maria L; Marchetti, Marcello; Fariselli, Laura; De Martin, Elena

2015-01-01

Aim of this study is to examine the feasibility of using the new Gafchromic EBT3 film in a high-dose stereotactic radiosurgery and radiotherapy quality assurance procedure. Owing to the reduced dimensions of the involved lesions, the feasibility of scanning plan verification films on the scanner plate area with the best uniformity rather than using a correction mask was evaluated. For this purpose, signal values dispersion and reproducibility of film scans were investigated. Uniformity was then quantified in the selected area and was found to be within 1.5% for doses up to 8 Gy. A high-dose threshold level for analyses using this procedure was established evaluating the sensitivity of the irradiated films. Sensitivity was found to be of the order of centiGray for doses up to 6.2 Gy and decreasing for higher doses. The obtained results were used to implement a procedure comparing dose distributions delivered with a CyberKnife system to planned ones. The procedure was validated through single beam irradiation on a Gafchromic film. The agreement between dose distributions was then evaluated for 13 patients (brain lesions, 5 Gy/die prescription isodose ~80%) using gamma analysis. Results obtained using Gamma test criteria of 5%/1 mm show a pass rate of 94.3%. Gamma frequency parameters calculation for EBT3 films showed to strongly depend on subtraction of unexposed film pixel values from irradiated ones. In the framework of the described dosimetric procedure, EBT3 films proved to be effective in the verification of high doses delivered to lesions with complex shapes and adjacent to organs at risk. Copyright © 2015 American Association of Medical Dosimetrists. Published by Elsevier Inc. All rights reserved.

[Diagnosis of cerebral metastasis with standard dose gadobutrol vs. a high dose protocol. Intraindividual evaluation of a phase II high dose study].

PubMed

Vogl, T J; Friebe, C E; Balzer, T; Mack, M G; Steiner, S; Schedel, H; Pegios, W; Lanksch, W; Banzer, D; Felix, R

1995-08-01

To assess the effectiveness and safety of normal and high doses of Gadobutrol versus a standard dose of Gadolinium DTPA in the MR evaluation of patients with brain metastases. In a clinical phase-II study 20 patients who had been diagnosed as having brain metastases with CT or MRT were studied prospectively with Gadobutrol, a new nonionic, low osmolality contrast agent. Each patient received an initial injection of 0.1 mmol/kg body weight and an additional dose of 0.2 mmol/kg Gadobutrol 10 min later. Spin-echo images were obtained before and after the two applications of Gadobutrol. Dynamic scanning (Turbo-FLASH) was performed for 3 min after each injection of the contrast agent. Both quantitative and qualitative data were intraindividually evaluated. The primary tumor was a bronchial carcinoma in 11 cases; in 9 other cases there were different primary tumors. Forty-eight hours after the use of Gadobutrol there were no adverse signs in the clinical examination, vital signs or blood and urine chemistry. Statistical analysis (Friedman test and Wilcoxon test) of the C/N ratios between tumor and white matter, percentage enhancement, and visual assessment rating revealed statistically significant superiority of high-dose Gadobutrol injection in comparison to the standard dose. The percentage enhancement increased on average from 104% after 0.1 mmol/kg to 162% after 0.3 mmol/kg Gadobutrol. Qualitative delineation and contrast of the lesions increased significantly. The use of high-dose Gadobutrol improved the detection of 36 additional lesions in 6 patients. The first in vivo results prove the excellent contrast capacity of the nonionic contrast agent Gadobutrol for the diagnosis of intracerebral metastases.

Dosimetric verification of stereotactic radiosurgery/stereotactic radiotherapy dose distributions using Gafchromic EBT3

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

Cusumano, Davide, E-mail: davide.cusumano@unimi.it; Fumagalli, Maria L.; Marchetti, Marcello

2015-10-01

Aim of this study is to examine the feasibility of using the new Gafchromic EBT3 film in a high-dose stereotactic radiosurgery and radiotherapy quality assurance procedure. Owing to the reduced dimensions of the involved lesions, the feasibility of scanning plan verification films on the scanner plate area with the best uniformity rather than using a correction mask was evaluated. For this purpose, signal values dispersion and reproducibility of film scans were investigated. Uniformity was then quantified in the selected area and was found to be within 1.5% for doses up to 8 Gy. A high-dose threshold level for analyses usingmore » this procedure was established evaluating the sensitivity of the irradiated films. Sensitivity was found to be of the order of centiGray for doses up to 6.2 Gy and decreasing for higher doses. The obtained results were used to implement a procedure comparing dose distributions delivered with a CyberKnife system to planned ones. The procedure was validated through single beam irradiation on a Gafchromic film. The agreement between dose distributions was then evaluated for 13 patients (brain lesions, 5 Gy/die prescription isodose ~80%) using gamma analysis. Results obtained using Gamma test criteria of 5%/1 mm show a pass rate of 94.3%. Gamma frequency parameters calculation for EBT3 films showed to strongly depend on subtraction of unexposed film pixel values from irradiated ones. In the framework of the described dosimetric procedure, EBT3 films proved to be effective in the verification of high doses delivered to lesions with complex shapes and adjacent to organs at risk.« less

Development of a stable and sensitive semiconductor detector by using a mixture of lead(II) iodide and lead monoxide for NDT radiation dose detection

NASA Astrophysics Data System (ADS)

Heo, Y. J.; Kim, K. T.; Han, M. J.; Moon, C. W.; Kim, J. E.; Park, J. K.; Park, S. K.

2018-03-01

Recently, high-energy radiation has been widely used in various industrial fields, including the medical industry, and increasing research efforts have been devoted to the development of radiation detectors to be used with high-energy radiation. In particular, nondestructive industrial applications use high-energy radiation for ships and multilayered objects for accurate inspection. Therefore, it is crucial to verify the accuracy of radiation dose measurements and evaluate the precision and reproducibility of the radiation output dose. Representative detectors currently used for detecting the dose in high-energy regions include Si diodes, diamond diodes, and ionization chambers. However, the process of preparing these detectors is complex in addition to the processes of conducting dosimetric measurements, analysis, and evaluation. Furthermore, the minimum size that can be prepared for a detector is limited. In the present study, the disadvantages of original detectors are compensated by the development of a detector made of a mixture of polycrystalline PbI2 and PbO powder, which are both excellent semiconducting materials suitable for detecting high-energy gamma rays and X-rays. The proposed detector shows characteristics of excellent reproducibility and stable signal detection in response to the changes in energy, and was analyzed for its applicability. Moreover, the detector was prepared through a simple process of particle-in-binder to gain control over the thickness and meet the specific value designated by the user. A mixture mass ratio with the highest reproducibility was determined through reproducibility testing with respect to changes in the photon energy. The proposed detector was evaluated for its detection response characteristics with respect to high-energy photon beam, in terms of dose-rate dependence, sensitivity, and linearity evaluation. In the reproducibility assessment, the detector made with 15 wt% PbO powder showed the best characteristics of 0.59% and 0.25% at 6 and 15 MV, respectively. Based on its selection in the reproducibility assessment, the 15 wt% PbO detector showed no dependence on the dose-rate changes, with R-SD < 1%. Finally, a coefficient of determination of 1 in the linearity assessment demonstrated very good linearity with regards to changes in dose. These results demonstrate the applicability and usefulness of the proposed detector made from a mixture of PbI2 and PbO semiconductors.

Factors Influencing Pulmonary Toxicity in Children Undergoing Allogeneic Hematopoietic Stem Cell Transplantation in the Setting of Total Body Irradiation-Based Myeloablative Conditioning.

PubMed

Abugideiri, Mustafa; Nanda, Ronica H; Butker, Charlotte; Zhang, Chao; Kim, Sungjin; Chiang, Kuang-Yueh; Butker, Elizabeth; Khan, Mohammad K; Haight, Ann E; Chen, Zhengjia; Esiashvili, Natia

2016-02-01

This study evaluated factors associated with increased risk of pulmonary toxicity (PT) from any cause in pediatric patients after myeloablative conditioning, using total body irradiation (TBI), followed by allogeneic hematopoietic stem cell transplantation (HSCT). The records of 129 consecutive pediatric patients (range: 1-21 years of age) who underwent TBI-based myeloablative conditioning for hematologic malignancies at our institution between January 2003 and May 2014 were reviewed. Although total TBI doses ranged from 10.5 to 14 Gy, lung doses were limited to 10 Gy with partial transmission blocks. TBI dose rates ranged from 5.6 cGy/min to 20.9 cGy/min. PT was classified using clinical symptoms, radiographic evidence, and ventilatory defects on pulmonary function tests. Noninfectious (idiopathic) pneumonia syndrome (IPS) was characterized by patients exhibiting PT while demonstrating no signs of infection throughout the follow-up period. PT from any cause developed in 70.5% of patients and was significantly associated with increased transplantation-related mortality (TRM) (P=.03) and decreased overall survival (OS) (P=.02). IPS developed in 23.3% of patients but was not associated with increased TRM (P=.6) or decreased OS (P=.5). Acute graft-versus-host disease (GVHD) significantly affected PT (P=.001) but did not significantly influence the development of IPS (P=.4). Infection was a leading cause of PT (75.8%). TBI dose rate significantly affected development of overall PT (P=.02) and was the sole factor to significantly influence the incidence of IPS (P=.002). TBI total dose, dose per fraction, disease type, transplantation chemotherapy, age of patient, sex, and donor type did not significantly impact overall PT or IPS. A high incidence of PT was noted in this large series of homogeneously treated pediatric patients undergoing TBI for allogeneic HSCT. TBI dose rates affected overall PT and strongly influenced IPS. TBI dose rate is a contributing factor influencing pulmonary toxicity and rates less than 15 cGy/min should be considered to decrease the risk of IPS. Copyright © 2016 Elsevier Inc. All rights reserved.

Factors Influencing Pulmonary Toxicity in Children Undergoing Allogeneic Hematopoietic Stem Cell Transplantation in the Setting of Total Body Irradiation-Based Myeloablative Conditioning

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

Abugideiri, Mustafa, E-mail: Mabugid@emory.edu; Nanda, Ronica H.; Butker, Charlotte

Purpose: This study evaluated factors associated with increased risk of pulmonary toxicity (PT) from any cause in pediatric patients after myeloablative conditioning, using total body irradiation (TBI), followed by allogeneic hematopoietic stem cell transplantation (HSCT). Methods and Materials: The records of 129 consecutive pediatric patients (range: 1-21 years of age) who underwent TBI-based myeloablative conditioning for hematologic malignancies at our institution between January 2003 and May 2014 were reviewed. Although total TBI doses ranged from 10.5 to 14 Gy, lung doses were limited to 10 Gy with partial transmission blocks. TBI dose rates ranged from 5.6 cGy/min to 20.9 cGy/min. PT was classified usingmore » clinical symptoms, radiographic evidence, and ventilatory defects on pulmonary function tests. Noninfectious (idiopathic) pneumonia syndrome (IPS) was characterized by patients exhibiting PT while demonstrating no signs of infection throughout the follow-up period. Results: PT from any cause developed in 70.5% of patients and was significantly associated with increased transplantation-related mortality (TRM) (P=.03) and decreased overall survival (OS) (P=.02). IPS developed in 23.3% of patients but was not associated with increased TRM (P=.6) or decreased OS (P=.5). Acute graft-versus-host disease (GVHD) significantly affected PT (P=.001) but did not significantly influence the development of IPS (P=.4). Infection was a leading cause of PT (75.8%). TBI dose rate significantly affected development of overall PT (P=.02) and was the sole factor to significantly influence the incidence of IPS (P=.002). TBI total dose, dose per fraction, disease type, transplantation chemotherapy, age of patient, sex, and donor type did not significantly impact overall PT or IPS. Conclusions: A high incidence of PT was noted in this large series of homogeneously treated pediatric patients undergoing TBI for allogeneic HSCT. TBI dose rates affected overall PT and strongly influenced IPS. TBI dose rate is a contributing factor influencing pulmonary toxicity and rates less than 15 cGy/min should be considered to decrease the risk of IPS.« less

Commissioning and quality assurance for VMAT delivery systems: An efficient time-resolved system using real-time EPID imaging.

PubMed

Zwan, Benjamin J; Barnes, Michael P; Hindmarsh, Jonathan; Lim, Seng B; Lovelock, Dale M; Fuangrod, Todsaporn; O'Connor, Daryl J; Keall, Paul J; Greer, Peter B

2017-08-01

An ideal commissioning and quality assurance (QA) program for Volumetric Modulated Arc Therapy (VMAT) delivery systems should assess the performance of each individual dynamic component as a function of gantry angle. Procedures within such a program should also be time-efficient, independent of the delivery system and be sensitive to all types of errors. The purpose of this work is to develop a system for automated time-resolved commissioning and QA of VMAT control systems which meets these criteria. The procedures developed within this work rely solely on images obtained, using an electronic portal imaging device (EPID) without the presence of a phantom. During the delivery of specially designed VMAT test plans, EPID frames were acquired at 9.5 Hz, using a frame grabber. The set of test plans was developed to individually assess the performance of the dose delivery and multileaf collimator (MLC) control systems under varying levels of delivery complexities. An in-house software tool was developed to automatically extract features from the EPID images and evaluate the following characteristics as a function of gantry angle: dose delivery accuracy, dose rate constancy, beam profile constancy, gantry speed constancy, dynamic MLC positioning accuracy, MLC speed and acceleration constancy, and synchronization between gantry angle, MLC positioning and dose rate. Machine log files were also acquired during each delivery and subsequently compared to information extracted from EPID image frames. The largest difference between measured and planned dose at any gantry angle was 0.8% which correlated with rapid changes in dose rate and gantry speed. For all other test plans, the dose delivered was within 0.25% of the planned dose for all gantry angles. Profile constancy was not found to vary with gantry angle for tests where gantry speed and dose rate were constant, however, for tests with varying dose rate and gantry speed, segments with lower dose rate and higher gantry speed exhibited less profile stability. MLC positional accuracy was not observed to be dependent on the degree of interdigitation. MLC speed was measured for each individual leaf and slower leaf speeds were shown to be compensated for by lower dose rates. The test procedures were found to be sensitive to 1 mm systematic MLC errors, 1 mm random MLC errors, 0.4 mm MLC gap errors and synchronization errors between the MLC, dose rate and gantry angle controls systems of 1°. In general, parameters measured by both EPID and log files agreed with the plan, however, a greater average departure from the plan was evidenced by the EPID measurements. QA test plans and analysis methods have been developed to assess the performance of each dynamic component of VMAT deliveries individually and as a function of gantry angle. This methodology relies solely on time-resolved EPID imaging without the presence of a phantom and has been shown to be sensitive to a range of delivery errors. The procedures developed in this work are both comprehensive and time-efficient and can be used for streamlined commissioning and QA of VMAT delivery systems. © 2017 American Association of Physicists in Medicine.

Space radiation risk limits and Earth-Moon-Mars environmental models

NASA Astrophysics Data System (ADS)

Cucinotta, Francis A.; Hu, Shaowen; Schwadron, Nathan A.; Kozarev, K.; Townsend, Lawrence W.; Kim, Myung-Hee Y.

2010-12-01

We review NASA's short-term and career radiation limits for astronauts and methods for their application to future exploration missions outside of low Earth orbit. Career limits are intended to restrict late occurring health effects and include a 3% risk of exposure-induced death from cancer and new limits for central nervous system and heart disease risks. Short-term dose limits are used to prevent in-flight radiation sickness or death through restriction of the doses to the blood forming organs and to prevent clinically significant cataracts or skin damage through lens and skin dose limits, respectively. Large uncertainties exist in estimating the health risks of space radiation, chiefly the understanding of the radiobiology of heavy ions and dose rate and dose protraction effects, and the limitations in human epidemiology data. To protect against these uncertainties NASA estimates the 95% confidence in the cancer risk projection intervals as part of astronaut flight readiness assessments and mission design. Accurate organ dose and particle spectra models are needed to ensure astronauts stay below radiation limits and to support the goal of narrowing the uncertainties in risk projections. Methodologies for evaluation of space environments, radiation quality, and organ doses to evaluate limits are discussed, and current projections for lunar and Mars missions are described.

SU-E-T-800: Verification of Acurose XB Dose Calculation Algorithm at Air Cavity-Tissue Interface Using Film Measurement for Small Fields of 6-MV Flattening Filter-Free Beams

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

Kang, S; Suh, T; Chung, J

2015-06-15

Purpose: To verify the dose accuracy of Acuros XB (AXB) dose calculation algorithm at air-tissue interface using inhomogeneous phantom for 6-MV flattening filter-free (FFF) beams. Methods: An inhomogeneous phantom included air cavity was manufactured for verifying dose accuracy at the air-tissue interface. The phantom was composed with 1 and 3 cm thickness of air cavity. To evaluate the central axis doses (CAD) and dose profiles of the interface, the dose calculations were performed for 3 × 3 and 4 × 4 cm{sup 2} fields of 6 MV FFF beams with AAA and AXB in Eclipse treatment plainning system. Measurements inmore » this region were performed with Gafchromic film. The root mean square errors (RMSE) were analyzed with calculated and measured dose profile. Dose profiles were divided into inner-dose profile (>80%) and penumbra (20% to 80%) region for evaluating RMSE. To quantify the distribution difference, gamma evaluation was used and determined the agreement with 3%/3mm criteria. Results: The percentage differences (%Diffs) between measured and calculated CAD in the interface, AXB shows more agreement than AAA. The %Diffs were increased with increasing the thickness of air cavity size and it is similar for both algorithms. In RMSEs of inner-profile, AXB was more accurate than AAA. The difference was up to 6 times due to overestimation by AAA. RMSEs of penumbra appeared to high difference for increasing the measurement depth. Gamma agreement also presented that the passing rates decreased in penumbra. Conclusion: This study demonstrated that the dose calculation with AXB shows more accurate than with AAA for the air-tissue interface. The 2D dose distributions with AXB for both inner-profile and penumbra showed better agreement than with AAA relative to variation of the measurement depths and air cavity sizes.« less

Accelerating an Ordered-Subset Low-Dose X-Ray Cone Beam Computed Tomography Image Reconstruction with a Power Factor and Total Variation Minimization.

PubMed

Huang, Hsuan-Ming; Hsiao, Ing-Tsung

2016-01-01

In recent years, there has been increased interest in low-dose X-ray cone beam computed tomography (CBCT) in many fields, including dentistry, guided radiotherapy and small animal imaging. Despite reducing the radiation dose, low-dose CBCT has not gained widespread acceptance in routine clinical practice. In addition to performing more evaluation studies, developing a fast and high-quality reconstruction algorithm is required. In this work, we propose an iterative reconstruction method that accelerates ordered-subsets (OS) reconstruction using a power factor. Furthermore, we combine it with the total-variation (TV) minimization method. Both simulation and phantom studies were conducted to evaluate the performance of the proposed method. Results show that the proposed method can accelerate conventional OS methods, greatly increase the convergence speed in early iterations. Moreover, applying the TV minimization to the power acceleration scheme can further improve the image quality while preserving the fast convergence rate.

Accelerating an Ordered-Subset Low-Dose X-Ray Cone Beam Computed Tomography Image Reconstruction with a Power Factor and Total Variation Minimization

PubMed Central

Huang, Hsuan-Ming; Hsiao, Ing-Tsung

2016-01-01

In recent years, there has been increased interest in low-dose X-ray cone beam computed tomography (CBCT) in many fields, including dentistry, guided radiotherapy and small animal imaging. Despite reducing the radiation dose, low-dose CBCT has not gained widespread acceptance in routine clinical practice. In addition to performing more evaluation studies, developing a fast and high-quality reconstruction algorithm is required. In this work, we propose an iterative reconstruction method that accelerates ordered-subsets (OS) reconstruction using a power factor. Furthermore, we combine it with the total-variation (TV) minimization method. Both simulation and phantom studies were conducted to evaluate the performance of the proposed method. Results show that the proposed method can accelerate conventional OS methods, greatly increase the convergence speed in early iterations. Moreover, applying the TV minimization to the power acceleration scheme can further improve the image quality while preserving the fast convergence rate. PMID:27073853

Metallic artifacts from internal scaphoid fracture fixation screws: comparison between C-arm flat-panel, cone-beam, and multidetector computed tomography.

PubMed

Finkenstaedt, Tim; Morsbach, Fabian; Calcagni, Maurizio; Vich, Magdalena; Pfirrmann, Christian W A; Alkadhi, Hatem; Runge, Val M; Andreisek, Gustav; Guggenberger, Roman

2014-08-01

The aim of this study was to compare image quality and extent of artifacts from scaphoid fracture fixation screws using different computed tomography (CT) modalities and radiation dose protocols. Imaging of 6 cadaveric wrists with artificial scaphoid fractures and different fixation screws was performed in 2 screw positions (45° and 90° orientation in relation to the x/y-axis) using multidetector CT (MDCT) and 2 flat-panel CT modalities, C-arm flat-panel CT (FPCT) and cone-beam CT (CBCT), the latter 2 with low and standard radiation dose protocols. Mean cartilage attenuation and metal artifact-induced absolute Hounsfield unit changes (= artifact extent) were measured. Two independent radiologists evaluated different image quality criteria using a 5-point Likert-scale. Interreader agreements (Cohen κ) were calculated. Mean absolute Hounsfield unit changes and quality ratings were compared using Friedman and Wilcoxon signed-rank tests. Artifact extent was significantly smaller for MDCT and standard-dose FPCT compared with CBCT low- and standard-dose acquisitions (all P < 0.05). No significant differences in artifact extent among different screw types and scanning positions were noted (P > 0.05). Both MDCT and FPCT standard-dose protocols showed equal ratings for screw bone interface, fracture line, and trabecular bone evaluation (P = 0.06, 0.2, and 0.2, respectively) and performed significantly better than FPCT low- and CBCT low- and standard-dose acquisitions (all P < 0.05). Good interreader agreement was found for image quality comparisons (Cohen κ = 0.76-0.78). Both MDCT and FPCT standard-dose acquisition showed comparatively less metal-induced artifacts and better overall image quality compared with FPCT low-dose and both CBCT acquisitions. Flat-panel CT may provide sufficient image quality to serve as a versatile CT alternative for postoperative imaging of internally fixated wrist fractures.

SU-G-BRC-16: Theory and Clinical Implications of the Constant Dosimetric Leaf Gap (DLG) Approximation

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

Kumaraswamy, L; Xu, Z; Podgorsak, M

Purpose: Commercial dose calculation algorithms incorporate a single DLG value for a given beam energy that is applied across an entire treatment field. However, the physical processes associated with beam generation and dose delivery suggest that the DLG is not constant. The aim of this study is to evaluate the variation of DLG among all leaf pairs, to quantify how this variation impacts delivered dose, and to establish a novel method to correct dose distributions calculated using the approximation of constant DLG. Methods: A 2D diode array was used to measure the DLG for all 60 leaf pairs at severalmore » points along each leaf pair travel direction. This approach was validated by comparison to DLG values measured at select points using a 0.6 cc ion chamber with the standard formalism. In-house software was developed to enable incorporation of position dependent DLG values into dose distribution optimization and calculation. The accuracy of beam delivery of both the corrected and uncorrected treatment plans was studied through gamma pass rate evaluation. A comparison of DVH statistics in corrected and uncorrected treatment plans was made. Results: The outer 20 MLC leaf pairs (1.0 cm width) have DLG values that are 0.32 mm (mean) to 0.65 mm (maximum) lower than the central leaf-pair. VMAT plans using a large number of 1 cm wide leaves were more accurately delivered (gamma pass rate increased by 5%) and dose coverage was higher (D100 increased by 3%) when the 2D DLG was modeled. Conclusion: Using a constant DLG value for a given beam energy will result in dose optimization, dose calculation and treatment delivery inaccuracies that become significant for treatment plans with high modulation complexity scores delivered with 1 cm wide leaves.« less

Pediatric 131I-MIBG Therapy for Neuroblastoma: Whole-Body 131I-MIBG Clearance, Radiation Doses to Patients, Family Caregivers, Medical Staff, and Radiation Safety Measures.

PubMed

Willegaignon, José; Crema, Karin Paola; Oliveira, Nathaliê Canhameiro; Pelissoni, Rogério Alexandre; Coura-Filho, George Barberio; Sapienza, Marcelo Tatit; Buchpiguel, Carlos Alberto

2018-06-19

I-metaiodobenzylguanidine (I-MIBG) has been used in the diagnosis and therapy of neuroblastoma in adult and pediatric patients for many years. In this study, we evaluated whole-body I-MIBG clearance and radiation doses received by patients, family caregivers, and medical staff to establish appropriate radiation safety measures to be used in therapy applications. Research was focused on 23 children and adolescents with metastatic neuroblastoma, with ages ranging from 1.8 to 13 years, being treated with I-MIBG. Based on measured external dose rates from patients, dosimetric data to patients, family members, and others were calculated. The mean ± SD I-MIBG activity administered was 8.55 ± 1.69 GBq. Percent whole-body retention rates of I-MIBG at 24, 48, and 72 hours after administration were 48% ± 7%, 23% ± 7%, and 12% ± 6%, with a whole-body I-MIBG effective half-life of 23 ± 5 hours for all patients. The mean doses for patients were 0.234 ± 0.096 mGy·MBq to red-marrow and 0.251 ± 0.101 mGy·MBq to whole body. The maximum potential radiation doses transmitted by patients to others at 1.0 m was estimated to be 11.9 ± 3.4 mSv, with 97% of this dose occurring over 120 hours after therapy administration. Measured mean dose received by the 22 family caregivers was 1.88 ± 1.85 mSv, and that received by the 19 pediatric physicians was 43 ± 51 μSv. In this study, we evaluated the whole-body clearance of I-MIBG in 23 pediatric patients, and the radiation doses received by family caregivers and medical staff during these therapy procedures, thus facilitating the establishment of radiation safety measures to be applied in pediatric therapy.

Low-Contrast and Low-Radiation Dose Protocol in Cardiac Computed Tomography: Usefulness of Low Tube Voltage and Knowledge-Based Iterative Model Reconstruction Algorithm.

PubMed

Iyama, Yuji; Nakaura, Takeshi; Yokoyama, Koichi; Kidoh, Masafumi; Harada, Kazunori; Oda, Seitaro; Tokuyasu, Shinichi; Yamashita, Yasuyuki

This study aimed to evaluate the feasibility of a low contrast, low-radiation dose protocol of 80-peak kilovoltage (kVp) with prospective electrocardiography-gated cardiac computed tomography (CT) using knowledge-based iterative model reconstruction (IMR). Thirty patients underwent an 80-kVp prospective electrocardiography-gated cardiac CT with low-contrast agent (222-mg iodine per kilogram of body weight) dose. We also enrolled 30 consecutive patients who were scanned with a 120-kVp cardiac CT with filtered back projection using the standard contrast agent dose (370-mg iodine per kilogram of body weight) as a historical control group. We evaluated the radiation dose for the 2 groups. The 80-kVp images were reconstructed with filtered back projection (protocol A), hybrid iterative reconstruction (HIR, protocol B), and IMR (protocol C). We compared CT numbers, image noise, and contrast-to-noise ratio among 120-kVp protocol, protocol A, protocol B, and protocol C. In addition, we compared the noise reduction rate between HIR and IMR. Two independent readers compared image contrast, image noise, image sharpness, unfamiliar image texture, and overall image quality among the 4 protocols. The estimated effective dose (ED) of the 80-kVp protocol was 74% lower than that of the 120-kVp protocol (1.4 vs 5.4 mSv). The contrast-to-noise ratio of protocol C was significantly higher than that of protocol A. The noise reduction rate of IMR was significantly higher than that of HIR (P < 0.01). There was no significant difference in almost all qualitative image quality between 120-kVp protocol and protocol C except for image contrast. A 80-kVp protocol with IMR yields higher image quality with 74% decreased radiation dose and 40% decreased contrast agent dose as compared with a 120-kVp protocol, while decreasing more image noise compared with the 80-kVp protocol with HIR.

Poster — Thur Eve — 36: Implementation of constant dose rate and gantry speed arc therapy(CDR-CAS-IMAT) for thoracic esophageal carcinoma on Varian 23EX

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

Zhang, Ruohui; Department of Medical Physics, Medical Faculty Mannheim, Heidelberg University; Fan, Xiaomei

2014-08-15

Objective: The purpose of this study is to propose an alternative planning approach for VMAT using constant dose rate and gantry speed arc therapy(CDR-CAS-IMAT) implementation on conventional Linac Varian 23EX and used IMRT as a benchmark to evaluate the performance. Methods and materials: Eighteen patients with thoracic esophageal carcinoma who were previously treated with IMRT on Varian 23EX were retrospectively planned for CDR-CAS-IMAT plans. Dose prescription was set to 60 Gy to PTVs in 30 fractions. The planning objectives for PTVs and OAR were corresponding with the IMRT plans. Dose to the PTVs and OAR were compared to IMRT withmore » respect to plan quality, MU, treatment time and delivery accuracy. Results: CDR-CAS-IMAT plans led to equivalent or superior plan quality as compared to IMRT, PTV's CI relative increased 16.2%, while small deviations were observed on minimum dose for PTV. Volumes in the cord receiving 40Gy were increased from 3.6% with IMRT to 7.0%. Treatment times were reduced significantly with CDR-CAS-IMAT(mean 85.7s vs. 232.1s, p < .05), however, MU increased by a factor of 1.3 and lung V10/5/3.5/aver were relative increase 6.7%,12%,17.9%,4.2%, respectively. And increased the E-P low dose area volume decreased the hight dose area. There were no significant difference in Delta4 measurements results between both planning techniques. Conclusion: CDR-CAS-IMAT plans can be implemented smoothly and quickly into a busy cancer center, which improved PTV CI and reduces treatment time but increased the MU and low dose irradiated area. An evaluation of weight loss must be performed during treatment for CDR-CAS-IMAT patients.« less

How do stimulant treatments for ADHD work? Evidence for mediation by improved cognition.

PubMed

Hawk, Larry W; Fosco, Whitney D; Colder, Craig R; Waxmonsky, James G; Pelham, William E; Rosch, Keri S

2018-05-07

Stimulant medications such as methylphenidate (MPH) are the frontline treatment for Attention-Deficit/Hyperactivity Disorder (ADHD). Despite their well-documented efficacy, the mechanisms by which stimulants improve clinical outcomes are not clear. The current study evaluated whether MPH effects on classroom behavior were mediated by improved cognitive functioning. Children with ADHD (n = 82; 9-12 years old) participated in a week-long summer research camp, consisting of cognitive testing, classroom periods, and recreational activities. After a baseline day, participants completed a 3-day randomized, double-blind, placebo-controlled trial of MPH (at doses approximating 0.3 and 0.6 mg/kg of immediate-release MPH dosed TID). Cognitive domains included inhibitory control (Stop Signal Task and prepulse inhibition of startle), attention (Continuous Performance Task and reaction time variability), and working memory (forward and backward spatial span). Clinical outcomes included math seatwork productivity and teacher-rated classroom behavior. A within-subjects path-analytic approach was used to test mediation. MPH-placebo and dose-response contrasts were used to evaluate drug effects. Methylphenidate improved seatwork productivity and teacher ratings (ds = 1.4 and 1.1) and all domains of cognition (ds = 0.3-1.1). Inhibitory control (Stop Signal Task, SST) and working memory backward uniquely mediated the effect of MPH (vs. placebo) on productivity. Only working memory backward mediated the impact of MPH on teacher-rated behavior. The dose-response (0.6 vs. 0.3 mg/kg) effects were more modest for clinical outcomes (ds = 0.4 and 0.2) and cognition (ds = 0-0.3); there was no evidence of cognitive mediation of the clinical dose-response effects. These findings are novel in demonstrating that specific cognitive processes mediate clinical improvement with stimulant treatment for ADHD. They converge with work on ADHD theory, neurobiology, and treatment development in suggesting that inhibitory control and working memory may be mechanisms of stimulant treatment response in ADHD. More work is necessary to evaluate the degree to which these findings generalize to chronic treatment, a broader array of clinical outcomes, and nonstimulant treatments. © 2018 Association for Child and Adolescent Mental Health.

Significant reduction in notification and seroprevalence rates of hepatitis B virus infection among the population of Zhejiang Province, China, aged between 1 and 29years from 2006 to 2014.

PubMed

Zhou, Yang; He, Hanqing; Deng, Xuan; Yan, Rui; Tang, Xuewen; Xie, Shuyun; Yao, Jun

2017-08-03

The Chinese government integrated hepatitis B vaccination into the national immunization program in 1992, when the hepatitis B birth dose was introduced in China. Zhejiang province is a relatively developed area in eastern China and was an area with high endemicity for hepatitis B virus (HBV) infection via mother-to-child transmission. The hepatitis B vaccine vaccination rates for the birth dose and 3- dose schedule in Zhejiang Province since 1992 have both remained above 90% [1]. The results of two hepatitis B seroepidemiological surveys conducted in 2006 and 2014, respectively, to evaluate the rates of notification and seroprevalence of HBV infection among the population of Zhejiang Province, China, aged between 1 and 29years. Data on the notification rates of HBV infection in Zhejiang province from 2006 to 2014 were obtained from the National Notifiable Disease Reporting System (NNDRS). The prevalence rate of HBV serological markers and the rate of immunization coverage were compared between surveys. The reported notification rates in people aged between 1 and 29years according to the NNDRS decreased approximately 4.88 times from 2006 to 2014. The prevalence of HBsAg decreased from 2.16% in 2006 to 1.05% in 2014, while the prevalence of anti-HBc decreased from 7.13% to 5.49%. The anti-HBc seroprevalence in the 15-29-year-old age group was significantly higher than that in all the other age groups both in the 2006 and 2014 serosurveys. The rate of anti-HBs seroprevalence in those aged between 1 and 14years was maintained at a high level between 2006 and 2014. The rate of hepatitis B reported and the rate of HBsAg positivity decreased significantly in Zhejiang province by maintaining the high-level coverage rate of the hepatitis B timely birth dose and three-dose schedule. While additional efforts are needed to achieve the goal of elimination. Copyright © 2017 Elsevier Ltd. All rights reserved.

Atmospheric Ionizing Radiation (AIR) ER-2 Preflight Analysis

NASA Technical Reports Server (NTRS)

Tai, Hsiang; Wilson, John W.; Maiden, D. L.

1998-01-01

Atmospheric ionizing radiation (AIR) produces chemically active radicals in biological tissues that alter the cell function or result in cell death. The AIR ER-2 flight measurements will enable scientists to study the radiation risk associated with the high-altitude operation of a commercial supersonic transport. The ER-2 radiation measurement flights will follow predetermined, carefully chosen courses to provide an appropriate database matrix which will enable the evaluation of predictive modeling techniques. Explicit scientific results such as dose rate, dose equivalent rate, magnetic cutoff, neutron flux, and air ionization rate associated with those flights are predicted by using the AIR model. Through these flight experiments, we will further increase our knowledge and understanding of the AIR environment and our ability to assess the risk from the associated hazard.

Institutional experience of interstitial brachytherapy for head and neck cancer with a comparison of high- and low dose rate practice.

PubMed

Mohanti, Bidhu Kalyan; Sahai, Puja; Thakar, Alok; Sikka, Kapil; Bhasker, Suman; Sharma, Atul; Sharma, Seema; Bahadur, Sudhir

2014-01-01

To describe our institutional experience with high dose rate (HDR) interstitial brachytherapy (IBT) compared with previously reported results on the low dose rate (LDR) practice for head and neck cancer. Eighty-four patients with oral cavity (n=70) or oropharyngeal cancer (n=14) were treated with 192Ir HDR-IBT. Seventy-eight patients had stage I or II tumour. The patients treated with IBT alone (n=42) received 39-42 Gy/10-14 fractions (median=40 Gy/10 fractions). With respect to the combination therapy group (n=42), prescription dose comprised of 12-18 Gy/3-6 fractions (median=15 Gy/5 fractions) for IBT and 40-50 Gy/20-25 fractions (median=50 Gy/25 fractions) for external radiotherapy. Brachytherapy was given as 2 fractions per day 6 hours apart with 4 Gy per fraction for monotherapy and 3 Gy per fraction for combination therapy. Four patients were not evaluable in the analysis of outcome. The primary site relapse rates were 23.8% (10/42) and 68.4% (26/38) in patients treated with IBT alone and combination therapy, respectively (p<0.001). Salvage surgery was performed in 19 patients. The 5-year local control rate was estimated at 62% and the disease-free survival (DFS) rate at 52% for all patients. Local control with respect to T1 and T2 tumours was 84% and 42%, respectively. Our present series on HDR-IBT and the previous report on LDR-IBT for head and neck cancer demonstrated similar DFS rates at 5 years (52%). The rate of regional failure in node-negative patients was <20% in both of our series. HDR-IBT offers similar results to LDR-IBT for head and neck cancer.

Intervention Fidelity: Aspects of Complementary and Alternative Medicine (CAM) Research

PubMed Central

Wyatt, Gwen; Sikorskii, Alla; Rahbar, Mohammad Hossein; Victorson, David; Adams, Lora

2010-01-01

Background The Treatment Fidelity Workgroup (TFW) established by the National Institutes of Health (NIH) provides a 5-point structure for intervention fidelity: dosing, interventionists’ consistency, intervention delivery, receipt and enactment of the intervention. Using our reflexology trial, we apply the first three points. Objectives Study objectives are to: 1) evaluate key dosage dimensions associated with CAM research; 2) evaluate approaches to interventionists’ consistency of delivery of CAM protocols; and 3) evaluate and discuss data that reflect CAM intervention fidelity. Intervention Women with late stage breast cancer (N=318) were randomly assigned to either 4 weeks of reflexology, placebo, or standard care. Results Dosing consists of three dimensions: frequency (4-sessions), duration (30 minutes), and interval between sessions (5–9 days). Interventionist consistency revealed over a 90% accuracy rate in following the protocol; 84% and 89% completion rate of the 4 session in the reflexology and placebo groups respectively; and no differences in attrition after randomization between reflexology and placebo groups (17% and 15%, respectively). Intervention delivery, examined through debriefing data, indicated a significantly higher rate of correct guesses on group assignment in the reflexology group as compared to the placebo (82% versus 46%, p-value=.0002). Conclusions This study points out the relevance of dosing, interventionists’ consistency, and delivery data within a CAM clinical trial, as well as the challenges of blinding. Implications Monitoring intervention fidelity by using the key areas identified by the BCC ensures that findings from a clinical trial are meaningful and have the potential to be translated to clinical practice. PMID:20467309

Ecotoxicological evaluation of tributyltin toxicity to the equilateral venus clam, Gomphina veneriformis (Bivalvia: Veneridae).

PubMed

Park, Kiyun; Kim, Rosa; Park, Jung Jun; Shin, Hyun Chool; Lee, Jung Sick; Cho, Hyeon Seo; Lee, Yeon Gyu; Kim, Jongkyu; Kwak, Inn-Sil

2012-03-01

Tributyltin (TBT) is the most common pesticide in marine and freshwater environments. To evaluate the potential ecological risk posed by TBT, we measured biological responses such as growth rate, gonad index, sex ratio, the percentage of intersex gonads, filtration rate, and gill abnormalities in the equilateral venus clam (Gomphina veneriformis). Additionally, the biochemical and molecular responses were evaluated in G. veneriformis exposed to various concentrations of TBT. The growth of G. veneriformis was significantly delayed in a dose-dependent manner after exposure to all tested TBT concentrations. After TBT was administered to G. veneriformis, the gonad index decreased and the sex balance was altered. The percentage of intersex gonads also increased significantly in treated females, whereas no intersex gonads were detected in the solvent control group. Additionally, intersex gonads were detected in male G. veneriformis specimens exposed to relatively high TBT concentrations (20 μg L⁻¹). The filtration rate was also reduced in a dose-dependent manner in TBT-exposed G. veneriformis. We also noted abnormal gill morphology in TBT-exposed G. veneriformis. Furthermore, increases in antioxidant enzyme activities were observed in TBT-exposed G. veneriformis clams, regardless of dosage. Vitellogenin gene expression also increased significantly in a dose-dependent manner in G. veneriformis exposed to TBT. These results provide valuable information regarding our understanding of the toxicology of TBT in G. veneriformis. Moreover, the responses of biological and molecular factors could be utilized as information for risk assessments and marine monitoring of TBT toxicity. Crown Copyright © 2011. Published by Elsevier Ltd. All rights reserved.

Ir-192 HDR transit dose and radial dose function determination using alanine/EPR dosimetry

NASA Astrophysics Data System (ADS)

Guzmán Calcina, Carmen S.; de Almeida, Adelaide; Oliveira Rocha, José R.; Abrego, Felipe Chen; Baffa, Oswaldo

2005-03-01

Source positioning close to the tumour in high dose rate (HDR) brachytherapy is not instantaneous. An increment of dose will be delivered during the movement of the source in the trajectory to its static position. This increment is the transit dose, often not taken into account in brachytherapeutic treatment planning. The transit dose depends on the prescribed dose, number of treatment fractions, velocity and activity of the source. Combining all these factors, the transit dose can be 5% higher than the prescribed absorbed dose value (Sang-Hyun and Muller-Runkel, 1994 Phys. Med. Biol. 39 1181 8, Nath et al 1995 Med. Phys. 22 209 34). However, it cannot exceed this percentage (Nath et al 1995). In this work, we use the alanine-EPR (electron paramagnetic resonance) dosimetric system using analysis of the first derivative of the signal. The transit dose was evaluated for an HDR system and is consistent with that already presented for TLD dosimeters (Bastin et al 1993 Int. J. Radiat. Oncol. Biol. Phys. 26 695 702). Also using the same dosimetric system, the radial dose function, used to evaluate the geometric dose degradation around the source, was determined and its behaviour agrees better with those obtained by Monte Carlo simulations (Nath et al 1995, Williamson and Nath 1991 Med. Phys. 18 434 48, Ballester et al 1997 Med. Phys. 24 1221 8, Ballester et al 2001 Phys. Med. Biol. 46 N79 90) than with TLD measurements (Nath et al 1990 Med. Phys. 17 1032 40).

Ir-192 HDR transit dose and radial dose function determination using alanine/EPR dosimetry.

PubMed

Calcina, Carmen S Guzmán; de Almeida, Adelaide; Rocha, José R Oliveira; Abrego, Felipe Chen; Baffa, Oswaldo

2005-03-21

Source positioning close to the tumour in high dose rate (HDR) brachytherapy is not instantaneous. An increment of dose will be delivered during the movement of the source in the trajectory to its static position. This increment is the transit dose, often not taken into account in brachytherapeutic treatment planning. The transit dose depends on the prescribed dose, number of treatment fractions, velocity and activity of the source. Combining all these factors, the transit dose can be 5% higher than the prescribed absorbed dose value (Sang-Hyun and Muller-Runkel, 1994 Phys. Med. Biol. 39 1181-8, Nath et al 1995 Med. Phys. 22 209-34). However, it cannot exceed this percentage (Nath et al 1995). In this work, we use the alanine-EPR (electron paramagnetic resonance) dosimetric system using analysis of the first derivative of the signal. The transit dose was evaluated for an HDR system and is consistent with that already presented for TLD dosimeters (Bastin et al 1993 Int. J. Radiat. Oncol. Biol. Phys. 26 695-702). Also using the same dosimetric system, the radial dose function, used to evaluate the geometric dose degradation around the source, was determined and its behaviour agrees better with those obtained by Monte Carlo simulations (Nath et al 1995, Williamson and Nath 1991 Med. Phys. 18 434-48, Ballester et al 1997 Med. Phys. 24 1221-8, Ballester et al 2001 Phys. Med. Biol. 46 N79-90) than with TLD measurements (Nath et al 1990 Med. Phys. 17 1032-40).

Dose rate effects in the radiation damage of the plastic scintillators of the CMS hadron endcap calorimeter

DOE PAGES

Khachatryan, V.; Sirunyan, A. M.; Tumasyan, A.; ...

2016-10-07

We present measurements of the reduction of light output by plastic scintillators irradiated in the CMS detector during the 8 TeV run of the Large Hadron Collider and show that they indicate a strong dose rate effect. The damage for a given dose is larger for lower dose rate exposures. The results agree with previous measurements of dose rate effects, but are stronger due to the very low dose rates probed. Here, we show that the scaling with dose rate is consistent with that expected from diffusion effects.

Pilot Study: Unique Response of Bone Tissue During an Investigation of Radio-Adaptive Effects in Mice

NASA Technical Reports Server (NTRS)

Sibonga, J. D.; Iwaniec, U.; Wu, H.

2011-01-01

PURPOSE: We obtained bone tissue to evaluate the collateral effects of experiments designed to investigate molecular mechanisms of radio-adaptation in a mouse model. Radio-adaptation describes a process by which the prior exposure to low dose radiation can protect against the toxic effect of a subsequent high dose exposure. In the radio-adaptation experiments, C57Bl/6 mice were exposed to either a Sham or a priming Low Dose (5 cGy) of Cs-137 gamma rays before being exposed to either a Sham or High Dose (6 Gy) 24 hours later. ANALYSIS: Bone tissue were obtained from two experiments where mice were sacrificed at 3 days (n=3/group, 12 total) and at 14 days (n=6/group, 24 total) following high dose exposure. Tissues were analyzed to 1) evaluate a radio-adaptive response in bone tissue and 2) describe cellular and microstructural effects for two skeletal sites with different rates of bone turnover. One tibia and one lumbar vertebrae (LV2), collected at the 3-day time-point, were analyzed by bone histomorphometry and micro-CT to evaluate the cellular response and any evidence of microarchitectural impact. Likewise, tibia and LV2, collected at the 14-day time-point, were analyzed by micro-CT alone to evaluate resulting changes to bone structure and microarchitecture. The data were analyzed by 2-way ANOVA to evaluate the effects of the priming low dose radiation, of the high dose radiation, and of any interaction between the priming low and high doses of radiation. Bone histomorphometry was performed in the cancellous bone (aka trabecular bone) compartments of the proximal tibial metaphysis and of LV2. RESULTS: Cellular Response @ 3 Days The priming Low Dose radiation decreased osteoblast-covered bone perimeter in the proximal tibia and the total cell density in the bone marrow in the LV2. High Dose radiation, regardless of prior exposure to priming dose, dramatically reduced total cell density in bone marrow of both the long bone and vertebra. However, in the proximal tibia, High Dose radiation increased the osteoclast-covered bone perimeters, the density of adipocytes in bone marrow, and the area of bone marrow occupied by fat cells -- while in the LV2, adipocytes were rare and not stimulated by High Dose radiation. In an unexpected response, High Dose radiation dramatically increased (10-fold) osteoblast-covered bone perimeter in the LV2.

Effects of dose scaling on delivery quality assurance in tomotherapy

PubMed Central

Nalichowski, Adrian; Burmeister, Jay

2012-01-01

Delivery quality assurance (DQA) of tomotherapy plans is routinely performed with silver halide film which has a limited range due to the effects of saturation. DQA plans with dose values exceeding this limit require the dose of the entire plan to be scaled downward if film is used, to evaluate the dose distribution in two dimensions. The potential loss of fidelity between scaled and unscaled DQA plans as a function of dose scaling is investigated. Three treatment plans for 12 Gy fractions designed for SBRT of the lung were used to create DQA procedures that were scaled between 100% and 10%. The dose was measured with an ionization chamber array and compared to values from the tomotherapy treatment planning system. Film and cylindrical ion chamber measurements were also made for one patient for scaling factors of 50% to 10% to compare with the ionization chamber array measurements. The array results show the average gamma pass rate is ≥99% from 100% to 30% scaling. The average gamma pass rate falls to 93.6% and 51.1% at 20% and 10% scaling, respectively. Film analysis yields similar pass rates. Cylindrical ion chambers did not exhibit significant variation with dose scaling, but only represent points in the low gradient region of the dose distribution. Scaling the dose changes the mechanics of the radiation delivery, as well as the signal‐to‐noise ratio. Treatment plans which exhibit parameters that differ significantly from those common to DQA plans studied in this paper may exhibit different behavior. Dose scaling should be limited to the smallest degree possible. Planar information, such as that from film or a detector array, is required. The results show that it is not necessary to perform both a scaled and unscaled DQA plan for the treatment plans considered here. PACS numbers: 87.55.km, 87.55.Qr PMID:22231213

Design and statistical considerations for studies evaluating the efficacy of a single dose of the human papillomavirus (HPV) vaccine.

PubMed

Sampson, Joshua N; Hildesheim, Allan; Herrero, Rolando; Gonzalez, Paula; Kreimer, Aimee R; Gail, Mitchell H

2018-05-01

Cervical cancer is a leading cause of cancer mortality in women worldwide. Human papillomavirus (HPV) types 16 and 18 cause about 70% of all cervical cancers. Clinical trials have demonstrated that three doses of either commercially available HPV vaccine, Cervarix ® or Gardasil ®, prevent most new HPV 16/18 infections and associated precancerous lesions. Based on evidence of immunological non-inferiority, 2-dose regimens have been licensed for adolescents in the United States, European Union, and elsewhere. However, if a single dose were effective, vaccine costs would be reduced substantially and the logistics of vaccination would be greatly simplified, enabling vaccination programs in developing countries. The National Cancer Institute (NCI) and the Agencia Costarricense de Investigaciones Biomédicas (ACIB) are conducting, with support from the Bill & Melinda Gates Foundation and the International Agency for Research on Cancer (IARC), a large 24,000 girl study to evaluate the efficacy of a 1-dose regimen. The first component of the study is a four-year non-inferiority trial comparing 1- to 2-dose regimens of the two licensed vaccines. The second component is an observational study that estimates the vaccine efficacy (VE) of each regimen by comparing the HPV infection rates in the trial arms to those in a contemporaneous survey group of unvaccinated girls. In this paper, we describe the design and statistical analysis for this study. We explain the advantage of defining non-inferiority on the absolute risk scale when the expected event rate is near 0 and, given this definition, suggest an approach to account for missing clinic visits. We then describe the problem of estimating VE in the absence of a randomized placebo arm and offer our solution. Copyright © 2018. Published by Elsevier Inc.

Sorafenib in advanced melanoma: a critical role for pharmacokinetics?

PubMed Central

Pécuchet, N; Lebbe, C; Mir, O; Billemont, B; Blanchet, B; Franck, N; Viguier, M; Coriat, R; Tod, M; Avril, M-F; Goldwasser, F

2012-01-01

Background: Inter-patient pharmacokinetic variability can lead to suboptimal drug exposure, and therefore might impact the efficacy of sorafenib. This study reports long-term pharmacokinetic monitoring of patients treated with sorafenib and a retrospective pharmacodynamic/pharmacokinetic analysis in melanoma patients. Patients and methods: Heavily pretreated patients with stage IV melanoma were started on sorafenib 400 mg twice daily (bid). In the absence of limiting toxicity, dose escalation of 200 mg bid levels was done every 2 weeks. Plasma sorafenib measurement was performed at each visit, allowing a retrospective pharmacodynamic/pharmacokinetic analysis for safety and efficacy. Results: In all, 19 of 30 patients underwent dose escalation over 400 mg bid, and 28 were evaluable for response. The overall disease control rate was 61% (95% confidence interval (CI): 42.6–78.8), including three confirmed responses (12%). Disease control rate and progression-free survival (PFS) were improved in patients with high vs low exposure (80% vs 32%, P=0.02, and 5.25 vs 2.5 months, P=0.005, hazard ratio (HR)=0.28 (95% CI: 0.11–0.73)). In contrast, drug dosing had no effect on PFS. In multivariate analysis, drug exposure was the only factor associated with PFS (HR=0.36 (95% CI: 0.13–0.99)). Diarrhoea and anorexia were correlated with drug dosing, while hypertension and hand–foot skin reaction were correlated with drug exposure. Conclusions: Although sorafenib had modest efficacy in melanoma, these results suggest a correlation between exposure and efficacy of sorafenib. Therefore, dose optimisation in patients with low exposure at standard doses should be evaluated in validated indications. PMID:22767146

Spatial interpolation and radiological mapping of ambient gamma dose rate by using artificial neural networks and fuzzy logic methods.

PubMed

Yeşilkanat, Cafer Mert; Kobya, Yaşar; Taşkın, Halim; Çevik, Uğur

2017-09-01

The aim of this study was to determine spatial risk dispersion of ambient gamma dose rate (AGDR) by using both artificial neural network (ANN) and fuzzy logic (FL) methods, compare the performances of methods, make dose estimations for intermediate stations with no previous measurements and create dose rate risk maps of the study area. In order to determine the dose distribution by using artificial neural networks, two main networks and five different network structures were used; feed forward ANN; Multi-layer perceptron (MLP), Radial basis functional neural network (RBFNN), Quantile regression neural network (QRNN) and recurrent ANN; Jordan networks (JN), Elman networks (EN). In the evaluation of estimation performance obtained for the test data, all models appear to give similar results. According to the cross-validation results obtained for explaining AGDR distribution, Pearson's r coefficients were calculated as 0.94, 0.91, 0.89, 0.91, 0.91 and 0.92 and RMSE values were calculated as 34.78, 43.28, 63.92, 44.86, 46.77 and 37.92 for MLP, RBFNN, QRNN, JN, EN and FL, respectively. In addition, spatial risk maps showing distributions of AGDR of the study area were created by all models and results were compared with geological, topological and soil structure. Copyright © 2017 Elsevier Ltd. All rights reserved.

Evaluation of ability of ferulic acid to control growth and fumonisin production of Fusarium verticillioides and Fusarium proliferatum on maize based media.

PubMed

Ferrochio, Laura; Cendoya, Eugenia; Farnochi, María Cecilia; Massad, Walter; Ramirez, María Laura

2013-10-15

The aim of this study was to evaluate the efficacy of ferulic acid (1, 10, 20 and 25 mM) at different water activity (aw) values (0.99, 0.98, 0.96 and 0.93) at 25 °C on growth and fumonisin production by Fusarium verticillioides and Fusarium proliferatum on maize based media. For both Fusarium species, the lag phase significantly decreased (p ≤ 0.001), and the growth rates increased (p ≤ 0.001) at the lowest ferulic acid concentration used (1mM), regardless of the aw. However, high doses of ferulic acid (10 to 25 mM) significantly reduced (p ≤ 0.001) the growth rate of both Fusarium species, regardless of the a(w). In general, growth rate inhibition increased as ferulic acid doses increased and as media aw decreased. Fumonisin production profiles of both Fusarium species showed that low ferulic acid concentrations (1-10mM) significantly increased (p ≤ 0.001) toxin production, regardless of the aw. High doses of ferulic acid (20-25 mM) reduced fumonisin production, in comparison with the controls, by both Fusarium species but they were not statistically significant in most cases. The results show that the use of ferulic acid as a post-harvest strategy to reduce mycotoxin accumulation on maize needs to be discussed. © 2013.

Hydrocortisone at stress-associated concentrations helps maintain human heart rate variability during subsequent endotoxin challenge.

PubMed

Rassias, Athos J; Guyre, Paul M; Yeager, Mark P

2011-12-01

We evaluated the differential impact of stress-associated vs high pharmacologic concentrations of hydrocortisone pretreatment on heart rate variability (HRV) during a subsequent systemic inflammatory stimulus. Healthy volunteers were randomized to receive placebo (Control) and hydrocortisone at 1.5 μg/kg per minute (STRESS) or at 3.0 μg/kg per minute (PHARM) as a 6-hour infusion. The STRESS dose was chosen to replicate the condition of physiologic adrenal cortical output during acute systemic stress. The PHARM dose was chosen to induce a supraphysiologic concentration of cortisol. The next day, all subjects received 2 ng/kg Escherichia coli endotoxin (lipopolysaccharide). Heart rate variability was analyzed with the statistic approximate entropy (ApEn). A lower ApEn correlates with decreased HRV. At the 3-hour nadir, the decrease in ApEn in the STRESS group was significantly less compared to placebo (P < .03), whereas ApEn in the PHARM group was not statistically different. We also found that the maximal decrease in ApEn preceded maximal increase in heart rate in all groups. The decrease in R-R interval was maximal at 4 hours, whereas the ApEn nadir was 1 hour earlier at 3 hours. Pretreatment with a stress dose of hydrocortisone but not a higher pharmacologic dose maintained a significantly higher ApEn after endotoxin exposure when compared to a placebo. In addition, decreases in ApEn preceded increases in heart rate. Copyright © 2011 Elsevier Inc. All rights reserved.

Effectiveness of previous mumps vaccination during a summer camp outbreak.

PubMed

Schaffzin, Joshua K; Pollock, Lynn; Schulte, Cynthia; Henry, Kyle; Dayan, Gustavo; Blog, Debra; Smith, Perry

2007-10-01

Mumps is a vaccine-preventable disease that may cause outbreaks. In July 2005, an outbreak of mumps occurred during a children's summer camp in upstate New York. An investigation was initiated to describe the cases and evaluate vaccine effectiveness. A retrospective cohort study was conducted among 541 children from the United States and abroad who attended a 1- or 2-month overnight summer camp. Patients with mumps were interviewed; serologic analysis was conducted for 6 case patients. Vaccine effectiveness was calculated by retrospective review of immunization records for 507 attendees who were eligible for vaccination and had verified immunization history. Thirty-one camp attendees were identified as having mumps (attack rate: 5.7%); 5 (83%) of 6 patients tested had positivity for mumps immunoglobulin M. Of the 507 participants (including 29 patients) with available immunization history, 440 (including 16 [87%] patients) were 2-dose recipients of mumps vaccine (attack rate: 3.6%); 46 participants (including 4 [9%] patients) were 1-dose recipients (attack rate: 8.7%); and 21 (including 9 [4%] patients) were unvaccinated (attack rate: 42.9%). Vaccine effectiveness was 92% for 2 doses and 80% for 1 dose. Outbreaks of mumps in settings such as summer camps can occur despite high vaccination rates. Vaccine effectiveness for 2 mumps vaccinations was greater than vaccine effectiveness for 1 mumps vaccination. Therefore, recommendation of 2 mumps vaccinations for summer camp participants continues to be appropriate. Control of mumps disease relies on broad vaccination coupled with correct clinical diagnosis and strict control measures.

Evaluation of Timing and Dosing of Caffeine Citrate in Preterm Neonates for the Prevention of Bronchopulmonary Dysplasia.

PubMed

Shenk, Eleni E; Bondi, Deborah S; Pellerite, Matthew M; Sriram, Sudhir

2018-01-01

The aim of this study was to evaluate the timing and dosing of caffeine therapy in relation to the development of bronchopulmonary dysplasia (BPD). This was a single-center, retrospective cohort study comparing early (days of life 0-2) to late (day of life 3 or greater) caffeine initiation in extremely low birth weight neonates, with a secondary analysis of large (10 mg/kg/day) to small dose (5 mg/kg/day) caffeine. There were 138 patients in the primary timing analysis. The early caffeine group had a lower incidence and reduced odds of the composite outcome of BPD or all-cause mortality, compared with the late caffeine group (64% vs. 88%, respectively; adjusted p < 0.05; adjusted OR 0.36 [95% CI 0.13-0.98]). No statistically significant difference was found between dosing groups (p = 0.29) in the primary outcome; however, there was a lower rate of patent ductus arteriosus requiring treatment (p = 0.05) and decreased likelihood of discharging home on oxygen (p = 0.02) in the large-dose group compared with the small-dose group. Early caffeine initiation significantly decreased the incidence of BPD or all-cause mortality in extremely low birth weight neonates. Patients receiving large-dose caffeine had improved secondary outcomes, although no difference in BPD was noted. Further studies are needed to determine the optimal dosing of caffeine.

Ascending Single-Dose, Double-Blind, Placebo-Controlled Safety Study of Noribogaine in Opioid-Dependent Patients.

PubMed

Glue, Paul; Cape, Gavin; Tunnicliff, Donna; Lockhart, Michelle; Lam, Fred; Hung, Noelyn; Hung, C Tak; Harland, Sarah; Devane, Jane; Crockett, R S; Howes, John; Darpo, Borje; Zhou, Meijian; Weis, Holger; Friedhoff, Lawrence

2016-11-01

Ibogaine is a psychoactive substance that may reduce opioid withdrawal symptoms. This was the first clinical trial of noribogaine, ibogaine's active metabolite, in patients established on methadone opioid substitution therapy (OST). In this randomized, double-blind, placebo-controlled single ascending-dose study, we evaluated the safety, tolerability, and pharmacokinetics of noribogaine in 27 patients seeking to discontinue methadone OST who had been switched to morphine during the previous week. Noribogaine doses were 60, 120, or 180 mg (n = 6/dose level) or matching placebo (n = 3/dose level). Noribogaine was well tolerated. The most frequent treatment-emergent adverse events were noneuphoric changes in light perception ∼1 hour postdose, headache, and nausea. Noribogaine had dose-linear increases for AUC and C max and was slowly eliminated (mean t 1/2 range, 24-30 hours). There was a concentration-dependent increase in QTcI (0.17 ms/ng/mL), with the largest observed mean effect of ∼16, 28, and 42 milliseconds in the 60-, 120-, and 180-mg groups, respectively. Noribogaine showed a nonstatistically significant trend toward decreased total score in opioid withdrawal ratings, most notably at the 120-mg dose; however, the study design may have confounded evaluations of time to resumption of OST. Future exposure-controlled multiple-dose noribogaine studies are planned that will address these safety and design issues. © 2016, The American College of Clinical Pharmacology.

Five-year antibody persistence in children after one dose of inactivated or live attenuated hepatitis A vaccine.

PubMed

Zhang, Zhilun; Zhu, Xiangjun; Hu, Yuansheng; Liang, Miao; Sun, Jin; Song, Yufei; Yang, Qi; Ji, Haiquan; Zeng, Gang; Song, Lifei; Chen, Jiangting

2017-06-03

In China, both inactivated hepatitis A (HA) vaccine and live attenuated HA vaccine are available. We conducted a trial to evaluate 5-year immune persistence induced by one dose of inactivated or live attenuated HA vaccines in children. Subjects with no HA vaccination history had randomly received one dose of inactivated or live attenuated HA vaccine at 18-60 months of age. Anti-HAV antibody concentrations were measured before vaccination and at the first, second, and fifth year after vaccination. Suspected cases of hepatitis A were monitored during the study period. A total of 332 subjects were enrolled and 182 provided evaluable serum samples at all planned time points. seropositive rate at 5 y was 85.9% in the inactivated HA vaccine group and 90.7% in the live attenuated HA vaccine group. GMCs were 76.3% mIU/ml (95% CI: 61.7 - 94.4) and 66.8mIU/ml (95% CI: 57.8 - 77.3), respectively. No significant difference in antibody persistence between 2 groups was found. No clinical hepatitis A case was reported. A single dose of an inactivated or live attenuated HA vaccine at 18-60 months of age resulted in high HAV seropositive rate and anti-HAV antibody concentrations that lasted for at least 5 y.

RadioImmunotherapy for adenoid cystic carcinoma: a single-institution series of combined treatment with cetuximab

PubMed Central

2010-01-01

Background Local control in adjuvant/definitive RT of adenoid cystic carcinoma (ACC) is largely dose-dependent. However, some clinical situations do not allow application of tumouricidal doses (i.e. re-irradiation) hence radiation sensitization by exploitation of high endothelial growth factor receptor (EGFR)-expression in ACC seems beneficial. This is a single-institution experience of combined radioimmunotherapy (RIT) with the EGFR-inhibitor cetuximab. Methods Between 2006 and 2010, 9 pts received RIT for advanced/recurrent ACC, 5/9 pts as re-irradiation. Baseline characteristics as well as treatment parameters were retrieved to evaluate efficacy and toxicity of the combination regimen were evaluated. Control rates (local/distant) and overall survival were calculated using Kaplan-Meier estimation. Results Median dose was 65 Gy, pts received a median of 6 cycles cetuximab. RIT was tolerated well with only one °III mucositis/dysphagia. Overall response/remission rates were high (77,8%); 2-year estimate of local control was 80% hence reaching local control levels comparable to high-dose RT. Progression-free survival (PFS) at 2 years and median overall survival were only 62,5% and 22,2 mo respectively. Conclusion While local control and treatment response in RIT seems promising, PFS and overall survival are still hampered by distant failure. The potential benefit of RIT with cetuximab warrants exploration in a prospective controlled clinical trial. PMID:21047402

Significance of manipulating tumour hypoxia and radiation dose rate in terms of local tumour response and lung metastatic potential, referring to the response of quiescent cell populations

PubMed Central

Masunaga, S; Matsumoto, Y; Kashino, G; Hirayama, R; Liu, Y; Tanaka, H; Sakurai, Y; Suzuki, M; Kinashi, Y; Maruhashi, A; Ono, K

2010-01-01

The purpose of this study was to evaluate the influence of manipulating intratumour oxygenation status and radiation dose rate on local tumour response and lung metastases following radiotherapy, referring to the response of quiescent cell populations within irradiated tumours. B16-BL6 melanoma tumour-bearing C57BL/6 mice were continuously given 5-bromo-2′-deoxyuridine (BrdU) to label all proliferating (P) cells. They received γ-ray irradiation at high dose rate (HDR) or reduced dose rate (RDR) following treatment with the acute hypoxia-releasing agent nicotinamide or local hyperthermia at mild temperatures (MTH). Immediately after the irradiation, cells from some tumours were isolated and incubated with a cytokinesis blocker. The responses of the quiescent (Q) and total (proliferating + Q) cell populations were assessed based on the frequency of micronuclei using immunofluorescence staining for BrdU. In other tumour-bearing mice, 17 days after irradiation, macroscopic lung metastases were enumerated. Following HDR irradiation, nicotinamide and MTH enhanced the sensitivity of the total and Q-cell populations, respectively. The decrease in sensitivity at RDR irradiation compared with HDR irradiation was slightly inhibited by MTH, especially in Q cells. Without γ-ray irradiation, nicotinamide treatment tended to reduce the number of lung metastases. With γ-rays, in combination with nicotinamide or MTH, especially the former, HDR irradiation decreased the number of metastases more remarkably than RDR irradiation. Manipulating both tumour hypoxia and irradiation dose rate have the potential to influence lung metastasis. The combination with the acute hypoxia-releasing agent nicotinamide may be more promising in HDR than RDR irradiation in terms of reducing the number of lung metastases. PMID:20739345

A Monte Carlo approach to the microdosimetric kinetic model to account for dose rate time structure effects in ion beam therapy with application in treatment planning simulations.

PubMed

Manganaro, Lorenzo; Russo, Germano; Cirio, Roberto; Dalmasso, Federico; Giordanengo, Simona; Monaco, Vincenzo; Muraro, Silvia; Sacchi, Roberto; Vignati, Anna; Attili, Andrea

2017-04-01

Advanced ion beam therapeutic techniques, such as hypofractionation, respiratory gating, or laser-based pulsed beams, have dose rate time structures which are substantially different from those found in conventional approaches. The biological impact of the time structure is mediated through the β parameter in the linear quadratic (LQ) model. The aim of this study was to assess the impact of changes in the value of the β parameter on the treatment outcomes, also accounting for noninstantaneous intrafraction dose delivery or fractionation and comparing the effects of using different primary ions. An original formulation of the microdosimetric kinetic model (MKM) is used (named MCt-MKM), in which a Monte Carlo (MC) approach was introduced to account for the stochastic spatio-temporal correlations characteristic of the irradiations and the cellular repair kinetics. A modified version of the kinetic equations, validated on experimental cell survival in vitro data, was also introduced. The model, trained on the HSG cells, was used to evaluate the relative biological effectiveness (RBE) for treatments with acute and protracted fractions. Exemplary cases of prostate cancer irradiated with different ion beams were evaluated to assess the impact of the temporal effects. The LQ parameters for a range of cell lines (V79, HSG, and T1) and ion species (H, He, C, and Ne) were evaluated and compared with the experimental data available in the literature, with good results. Notably, in contrast to the original MKM formulation, the MCt-MKM explicitly predicts an ion and LET-dependent β compatible with observations. The data from a split-dose experiment were used to experimentally determine the value of the parameter related to the cellular repair kinetics. Concerning the clinical case considered, an RBE decrease was observed, depending on the dose, ion, and LET, exceeding up to 3% of the acute value in the case of a protraction in the delivery of 10 min. The intercomparison between different ions shows that the clinical optimality is strongly dependent on a complex interplay between the different physical and biological quantities considered. The present study provides a framework for exploiting the temporal effects of dose delivery. The results show the possibility of optimizing the treatment outcomes accounting for the correlation between the specific dose rate time structure and the spatial characteristic of the LET distribution, depending on the ion type used. © 2017 American Association of Physicists in Medicine.

SU-F-BRA-11: An Experimental Commissioning Test of Brachytherapy MBDCA Dosimetry, Based On a Commercial Radiochromic Gel/optical CT System

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

Pappas, E; Karaiskos, P; Zourari, K

2015-06-15

Purpose: To implement a 3D dose verification procedure of Model-Based Dose Calculation Algorithms (MBDCAs) for {sup 192}Ir HDR brachytherapy, based on a novel Ferrous Xylenol-orange gel (FXG) and optical CT read-out. Methods: The TruView gel was employed for absolute dosimetry in conjunction with cone-beam optical CT read-out with the VISTA scanner (both from Modus Medical Inc, London, ON, Canada). A multi-catheter skin flap was attached to a cylindrical PETE jar (d=9.6cm, h=16cm) filled with FXG, which served as both the dosimeter and the water equivalent phantom of bounded dimensions. X- ray CT image series of the jar with flap attachedmore » was imported to Oncentra Brachy v.4.5. A treatment plan consisting of 8 catheters and 56 dwell positions was generated, and Oncentra-ACE MBDCA as well as TG43 dose results were exported for further evaluation. The irradiation was carried out with a microSelecton v2 source. The FXG dose-response, measured via an electron irradiation of a second dosimeter from the same batch, was linear (R2>0.999) at least up to 12Gy. A MCNP6 input file was prepared from the DICOM-RT plan data using BrachyGuide to facilitate Monte Carlo (MC) simulation dosimetry in the actual experimental geometry. Agreement between experimental (reference) and calculated dose distributions was evaluated using the 3D gamma index (GI) method with criteria (5%-2mm applied locally) determined from uncertainty analysis. Results: The TG-43 GI failed, as expected, in the majority of voxels away from the flap (pass rate 59% for D>0.8Gy, corresponding to 10% of prescribed dose). ACE performed significantly better (corresponding pass rate 92%). The GI evaluation for the MC data (corresponding pass rate 97%) failed mainly at low dose points of increased uncertainty. Conclusion: FXG gel/optical CT is an efficient method for level-2 commissioning of brachytherapy MBDCAs. Target dosimetry is not affected from uncertainty introduced by TG43 assumptions in 192Ir skin brachytherapy. Research co-financed by the ESF and Greek funds through the Operational Program Education and Lifelong Learning Investing in Knowledge Society of the NSRF. Research Funding Program: Aristeia. Modus Medical Devices Inc. provided a TruView dosimeter batch and Nucletron, and Elekta company, provided access to Oncentra Brachy v4.5, for research purposes.« less

Impact of temporal probability in 4D dose calculation for lung tumors.

PubMed

Rouabhi, Ouided; Ma, Mingyu; Bayouth, John; Xia, Junyi

2015-11-08

The purpose of this study was to evaluate the dosimetric uncertainty in 4D dose calculation using three temporal probability distributions: uniform distribution, sinusoidal distribution, and patient-specific distribution derived from the patient respiratory trace. Temporal probability, defined as the fraction of time a patient spends in each respiratory amplitude, was evaluated in nine lung cancer patients. Four-dimensional computed tomography (4D CT), along with deformable image registration, was used to compute 4D dose incorporating the patient's respiratory motion. First, the dose of each of 10 phase CTs was computed using the same planning parameters as those used in 3D treatment planning based on the breath-hold CT. Next, deformable image registration was used to deform the dose of each phase CT to the breath-hold CT using the deformation map between the phase CT and the breath-hold CT. Finally, the 4D dose was computed by summing the deformed phase doses using their corresponding temporal probabilities. In this study, 4D dose calculated from the patient-specific temporal probability distribution was used as the ground truth. The dosimetric evaluation matrix included: 1) 3D gamma analysis, 2) mean tumor dose (MTD), 3) mean lung dose (MLD), and 4) lung V20. For seven out of nine patients, both uniform and sinusoidal temporal probability dose distributions were found to have an average gamma passing rate > 95% for both the lung and PTV regions. Compared with 4D dose calculated using the patient respiratory trace, doses using uniform and sinusoidal distribution showed a percentage difference on average of -0.1% ± 0.6% and -0.2% ± 0.4% in MTD, -0.2% ± 1.9% and -0.2% ± 1.3% in MLD, 0.09% ± 2.8% and -0.07% ± 1.8% in lung V20, -0.1% ± 2.0% and 0.08% ± 1.34% in lung V10, 0.47% ± 1.8% and 0.19% ± 1.3% in lung V5, respectively. We concluded that four-dimensional dose computed using either a uniform or sinusoidal temporal probability distribution can approximate four-dimensional dose computed using the patient-specific respiratory trace.

Characterizing dose response relationships: Chronic gamma radiation in Lemna minor induces oxidative stress and altered polyploidy level.

PubMed

Van Hoeck, Arne; Horemans, Nele; Van Hees, May; Nauts, Robin; Knapen, Dries; Vandenhove, Hildegarde; Blust, Ronny

2015-12-01

The biological effects and interactions of different radiation types in plants are still far from understood. Among different radiation types, external gamma radiation treatments have been mostly studied to assess the biological impact of radiation toxicity in organisms. Upon exposure of plants to gamma radiation, ionisation events can cause, either directly or indirectly, severe biological damage to DNA and other biomolecules. However, the biological responses and oxidative stress related mechanisms under chronic radiation conditions are poorly understood in plant systems. In the following study, it was questioned if the Lemna minor growth inhibition test is a suitable approach to also assess the radiotoxicity of this freshwater plant. Therefore, L. minor plants were continuously exposed for seven days to 12 different dose rate levels covering almost six orders of magnitude starting from 80 μGy h(-1) up to 1.5 Gy h(-1). Subsequently, growth, antioxidative defence system and genomic responses of L. minor plants were evaluated. Although L. minor plants could survive the exposure treatment at environmental relevant exposure conditions, higher dose rate levels induced dose dependent growth inhibitions starting from approximately 27 mGy h(-1). A ten-percentage growth inhibition of frond area Effective Dose Rate (EDR10) was estimated at 95 ± 7 mGy h(-1), followed by 153 ± 13 mGy h(-1) and 169 ± 12 mGy h(-1) on fresh weight and frond number, respectively. Up to a dose rate of approximately 5 mGy h(-1), antioxidative enzymes and metabolites remained unaffected in plants. A significant change in catalase enzyme activity was found at 27 mGy h(-1) which was accompanied with significant increases of other antioxidative enzyme activities and shifts in ascorbate and glutathione content at higher dose rate levels, indicating an increase in oxidative stress in plants. Recent plant research hypothesized that environmental genotoxic stress conditions can induce endoreduplication events. Here an increase in ploidy level was observed at the highest tested dose rate. In conclusion, the results revealed that in plants several mechanisms and pathways interplay to cope with radiation induced stress. Copyright © 2015 Elsevier Ltd. All rights reserved.

Computational study of radiation doses at UNLV accelerator facility

NASA Astrophysics Data System (ADS)

Hodges, Matthew; Barzilov, Alexander; Chen, Yi-Tung; Lowe, Daniel

2017-09-01

A Varian K15 electron linear accelerator (linac) has been considered for installation at University of Nevada, Las Vegas (UNLV). Before experiments can be performed, it is necessary to evaluate the photon and neutron spectra as generated by the linac, as well as the resulting dose rates within the accelerator facility. A computational study using MCNPX was performed to characterize the source terms for the bremsstrahlung converter. The 15 MeV electron beam available in the linac is above the photoneutron threshold energy for several materials in the linac assembly, and as a result, neutrons must be accounted for. The angular and energy distributions for bremsstrahlung flux generated by the interaction of the 15 MeV electron beam with the linac target were determined. This source term was used in conjunction with the K15 collimators to determine the dose rates within the facility.

The Shigella human challenge model.

PubMed

Porter, C K; Thura, N; Ranallo, R T; Riddle, M S

2013-02-01

Shigella is an important bacterial cause of infectious diarrhoea globally. The Shigella human challenge model has been used since 1946 for a variety of objectives including understanding disease pathogenesis, human immune responses and allowing for an early assessment of vaccine efficacy. A systematic review of the literature regarding experimental shigellosis in human subjects was conducted. Summative estimates were calculated by strain and dose. While a total of 19 studies evaluating nine strains at doses ranging from 10 to 1 × 1010 colony-forming units were identified, most studies utilized the S. sonnei strain 53G and the S. flexneri strain 2457T. Inoculum solution and pre-inoculation buffering has varied over time although diarrhoea attack rates do not appear to increase above 75-80%, and dysentery rates remain fairly constant, highlighting the need for additional dose-ranging studies. Expansion of the model to include additional strains from different serotypes will elucidate serotype and strain-specific outcome variability.

Adenoid cystic salivary gland carcinoma: treatment with irradiation and surgery

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

Simpson, J.R.; Thawley, S.E.; Matsuba, H.M.

1984-05-01

The recrods of 71 patients with adenoid cystic carcinoma of the salivary glands were reviewed to determine the dose response relationships for this aggressive tumor. Local control after treament was determined for all patients and analyzed with respect to extent of surgery and dose of radiation. Of 70 patients who were available for evaluation of local control, 28 (40%) had a local recurrence and 42 (60%) did not. The highest control rates were found in patients who underwent both radiation therapy and surgery. Patients who received a dose equal to or greater than 6,000 rad (60 Gy) in addition tomore » surgery had significantly higher local control rates than those who received less than 6,000 rad (60 Gy). Distant metastases developed in 50% of patients regardless of local control, with the following distribution: 39% lung, 19% bone, and 10% disseminated soft-tissue metastases.« less

Seropositivity among Korean Young Adults Approximately 2 Years after a Single-Dose Vaccination against Hepatitis A Virus.

PubMed

Song, Yeong-Jun; Lim, Jiseun; Park, Woong-Sub; Sohn, Haesook; Lee, Moo-Sik; Shin, Dong-Hoon; Kim, Chun-Bae; Kim, Hwasung; Oh, Gyung-Jae; Ki, Moran

2015-01-01

We previously observed 80.7% seropositivity and a significant interaction between gender and hepatitis A virus (HAV) vaccine type (Havrix vs. Epaxal) on the seropositivity approximately 11 months after single-dose HAV vaccinations in Korean young adults. Our objective was to evaluate seropositivity approximately 2 years after a single-dose HAV vaccination and the influence of demographic characteristics on seropositivity, including the interaction between gender and vaccine type. Seronegative medical school students were randomly vaccinated with Havrix or Epaxal. Based on a total serum anti-HAV antibody titer cutoff of 20 IU/mL, 338 participants (76.0%) of the 445 vaccinees were seropositive 20-25 months after a single-dose HAV vaccination. The seropositive rates were similar after vaccination with Havrix (77.0%) and Epaxal (74.9%). Univariate analysis indicated that female (p = 0.052) and less obese (p < 0.001) participants had a higher seropositive rate, whereas other characteristics such as age, alcohol use, smoking history, vaccine type, and follow-up duration were not associated with seropositivity. Multivariate analysis indicated that women (p = 0.026) and participants with moderate alcohol use (p < 0.001) showed significantly higher seropositive rates than men and participants with no or low alcohol use, respectively. The seropositive rates after vaccination with Havrix and Epaxal were 70.9% and 67.5% in men and 87.7% and 91.3% in women, respectively (p for interaction = 0.304). Compared with the seropositive rate approximately 11 months after vaccination, the seropositive rate decreased substantially only in men in the Havrix group (11.0% points), and consequently, the interaction between gender and vaccine type disappeared while seropositivity remained high (87.7% and 91.3% in Havrix and Epaxal groups, respectively) among women approximately 2 years after vaccination. Further studies are needed to assess whether the seropositive rate would be maintained in all groups more than 2 years after a single-dose HAV vaccination.

The relation between doses or post-plasma time points and apoptosis of leukemia cells induced by dielectric barrier discharge plasma

NASA Astrophysics Data System (ADS)

Wang, Chao; Zhang, Haixia; Xue, Zhixiao; Yin, Huijuan; Niu, Qing; Chen, Hongli

2015-12-01

The dielectric barrier discharge (DBD) plasma was applied to induce apoptosis of LT-12 leukemia cells. Plasma effects on cell death was evaluated by MTT assay and FCM apoptosis assay with Annexin V/PI double staining, suggesting that plasma killing cells rate and inducing cell apoptosis rate both positively were related to the plasma doses or the post-plasma time points. The cell death rates increased from 15.2% to 33.1% and the apoptosis rate raise from 23.8% to 28% when the dose raise from 60s to 120 s at 8 h post-plasma, while they increased from 15.4% to 34.9% and from 48% to 55.3% respectively at the same doses at 12 h post-plasma. Furthermore, the production of reactive oxygen species (ROS), gene and protein expression for Caspases and Bcl-2 family members were measured for exploring the related apoptotic mechanisms phenomenon. We found ROS immediately increased to 1.24 times of the original amount, then increasing to 5.39-fold at 20 h after treatment. The gene and protein expression for Caspases and Bcl-2 family members are very active at 8-12 h post-plasma. Our results demonstrate that DBD plasma can effectively induce tumor cell death through primarily related apoptotic mechanisms.

Effects of acute buspirone administration on inhibitory control and sexual discounting in cocaine users.

PubMed

Strickland, Justin C; Bolin, B Levi; Romanelli, Michael R; Rush, Craig R; Stoops, William W

2017-01-01

Cocaine users display deficits in inhibitory control and make impulsive choices that may increase risky behavior. Buspirone is an anxiolytic that activates dopaminergic and serotonergic systems and improves impulsive choice (i.e., reduces sexual risk-taking intent) in cocaine users when administered chronically. We evaluated the effects of acutely administered buspirone on inhibitory control and impulsive choice. Eleven subjects with a recent history of cocaine use completed this within-subject, placebo-controlled study. Subjects performed two cued go/no-go and a sexual risk delay-discounting task following oral administration of buspirone (10 and 30 mg), triazolam (0.375 mg; positive control), and placebo (negative control). Physiological and psychomotor performance and subject-rated data were also collected. Buspirone failed to change inhibitory control or impulsive choice; however, slower reaction times were observed at the highest dose tested. Buspirone did not produce subject-rated drug effects but dose-dependently decreased diastolic blood pressure. Triazolam impaired psychomotor performance and increased ratings of positive subject-rated effects (e.g., Like Drug). These findings indicate that acutely administered buspirone has little impact on behavioral measures of inhibitory control and impulsive sexual decision-making. Considering previous findings with chronic dosing, these findings highlight that the behavioral effects of buspirone differ as a function of dosing conditions. Copyright © 2017 John Wiley & Sons, Ltd.

Artemether-lumefantrine dosing for malaria treatment in young children and pregnant women: A pharmacokinetic-pharmacodynamic meta-analysis

PubMed Central

Borrmann, Steffen; Tékété, Mamadou; Lefèvre, Gilbert; Hamed, Kamal; Piola, Patrice; Ursing, Johan; Kofoed, Poul Erik; Mårtensson, Andreas; Ngasala, Billy; Björkman, Anders; Friberg Hietala, Sofia; Aweeka, Francesca; Parikh, Sunil; Mwai, Leah; Davis, Timothy M. E.; Karunajeewa, Harin; Newton, Paul N.; Mayxay, Mayfong; Deloron, Philippe; van Vugt, Michele; Karbwang, Juntra; Ezzet, Farkad; Bakshi, Rajesh; Stepniewska, Kasia; Barnes, Karen I.

2018-01-01

Background The fixed dose combination of artemether-lumefantrine (AL) is the most widely used treatment for uncomplicated Plasmodium falciparum malaria. Relatively lower cure rates and lumefantrine levels have been reported in young children and in pregnant women during their second and third trimester. The aim of this study was to investigate the pharmacokinetic and pharmacodynamic properties of lumefantrine and the pharmacokinetic properties of its metabolite, desbutyl-lumefantrine, in order to inform optimal dosing regimens in all patient populations. Methods and findings A search in PubMed, Embase, ClinicalTrials.gov, Google Scholar, conference proceedings, and the WorldWide Antimalarial Resistance Network (WWARN) pharmacology database identified 31 relevant clinical studies published between 1 January 1990 and 31 December 2012, with 4,546 patients in whom lumefantrine concentrations were measured. Under the auspices of WWARN, relevant individual concentration-time data, clinical covariates, and outcome data from 4,122 patients were made available and pooled for the meta-analysis. The developed lumefantrine population pharmacokinetic model was used for dose optimisation through in silico simulations. Venous plasma lumefantrine concentrations 7 days after starting standard AL treatment were 24.2% and 13.4% lower in children weighing <15 kg and 15–25 kg, respectively, and 20.2% lower in pregnant women compared with non-pregnant adults. Lumefantrine exposure decreased with increasing pre-treatment parasitaemia, and the dose limitation on absorption of lumefantrine was substantial. Simulations using the lumefantrine pharmacokinetic model suggest that, in young children and pregnant women beyond the first trimester, lengthening the dose regimen (twice daily for 5 days) and, to a lesser extent, intensifying the frequency of dosing (3 times daily for 3 days) would be more efficacious than using higher individual doses in the current standard treatment regimen (twice daily for 3 days). The model was developed using venous plasma data from patients receiving intact tablets with fat, and evaluations of alternative dosing regimens were consequently only representative for venous plasma after administration of intact tablets with fat. The absence of artemether-dihydroartemisinin data limited the prediction of parasite killing rates and recrudescent infections. Thus, the suggested optimised dosing schedule was based on the pharmacokinetic endpoint of lumefantrine plasma exposure at day 7. Conclusions Our findings suggest that revised AL dosing regimens for young children and pregnant women would improve drug exposure but would require longer or more complex schedules. These dosing regimens should be evaluated in prospective clinical studies to determine whether they would improve cure rates, demonstrate adequate safety, and thereby prolong the useful therapeutic life of this valuable antimalarial treatment. PMID:29894518

Characterization of a new transmission detector for patient individualized online plan verification and its influence on 6MV X-ray beam characteristics.

PubMed

Thoelking, Johannes; Sekar, Yuvaraj; Fleckenstein, Jens; Lohr, Frank; Wenz, Frederik; Wertz, Hansjoerg

2016-09-01

Online verification and 3D dose reconstruction on daily patient anatomy have the potential to improve treatment delivery, accuracy and safety. One possible implementation is to recalculate dose based on online fluence measurements with a transmission detector (TD) attached to the linac. This study provides a detailed analysis of the influence of a new TD on treatment beam characteristics. The influence of the new TD on surface dose was evaluated by measurements with an Advanced Markus Chamber (Adv-MC) in the build-up region. Based on Monte Carlo simulations, correction factors were determined to scale down the over-response of the Adv-MC close to the surface. To analyze the effects beyond dmax percentage depth dose (PDD), lateral profiles and transmission measurements were performed. All measurements were carried out for various field sizes and different SSDs. Additionally, 5 IMRT-plans (head & neck, prostate, thorax) and 2 manually created test cases (3×3cm(2) fields with different dose levels, sweeping gap) were measured to investigate the influence of the TD on clinical treatment plans. To investigate the performance of the TD, dose linearity as well as dose rate dependency measurements were performed. With the TD inside the beam an increase in surface dose was observed depending on SSD and field size (maximum of +11%, SSD = 80cm, field size = 30×30cm(2)). Beyond dmax the influence of the TD on PDDs was below 1%. The measurements showed that the transmission factor depends slightly on the field size (0.893-0.921 for 5×5cm(2) to 30×30cm(2)). However, the evaluation of clinical IMRT-plans measured with and without the TD showed good agreement after using a single transmission factor (γ(2%/2mm) > 97%, δ±3% >95%). Furthermore, the response of TD was found to be linear and dose rate independent (maximum difference <0.5% compared to reference measurements). When placed in the path of the beam, the TD introduced a slight, clinically acceptable increase of the skin dose even for larger field sizes and smaller SSDs and the influence of the detector on the dose beyond dmax as well as on clinical IMRT-plans was negligible. Since there was no dose rate dependency and the response was linear, the device is therefore suitable for clinical use. Only its absorption has to be compensated during treatment planning, either by the use of a single transmission factor or by including the TD in the incident beam model. Copyright © 2015. Published by Elsevier GmbH.

Preclinical dose number and its application in understanding drug absorption risk and formulation design for preclinical species.

PubMed

Wuelfing, W Peter; Daublain, Pierre; Kesisoglou, Filippos; Templeton, Allen; McGregor, Caroline

2015-04-06

In the drug discovery setting, the ability to rapidly identify drug absorption risk in preclinical species at high doses from easily measured physical properties is desired. This is due to the large number of molecules being evaluated and their high attrition rate, which make resource-intensive in vitro and in silico evaluation unattractive. High-dose in vivo data from rat, dog, and monkey are analyzed here, using a preclinical dose number (PDo) concept based on the dose number described by Amidon and other authors (Pharm. Res., 1993, 10, 264-270). PDo, as described in this article, is simply calculated as dose (mg/kg) divided by compound solubility in FaSSIF (mg/mL) and approximates the volume of biorelevant media per kilogram of animal that would be needed to fully dissolve the dose. High PDo values were found to be predictive of difficulty in achieving drug exposure (AUC)-dose proportionality in in vivo studies, as could be expected; however, this work analyzes a large data set (>900 data points) and provides quantitative guidance to identify drug absorption risk in preclinical species based on a single solubility measurement commonly carried out in drug discovery. Above the PDo values defined, >50% of all in vivo studies exhibited poor AUC-dose proportionality in rat, dog, and monkey, and these values can be utilized as general guidelines in discovery and early development to rapidly assess risk of solubility-limited absorption for a given compound. A preclinical dose number generated by biorelevant dilutions of formulated compounds (formulated PDo) was also evaluated and defines solubility targets predictive of suitable AUC-dose proportionality in formulation development efforts. Application of these guidelines can serve to efficiently identify compounds in discovery that are likely to present extreme challenges with respect to solubility-limited absorption in preclinical species as well as reduce the testing of poor formulations in vivo, which is a key ethical and resource matter.

Advanced dosimetry systems for the space transport and space station

NASA Technical Reports Server (NTRS)

Wailly, L. F.; Schneider, M. F.; Clark, B. C.

1972-01-01

Advanced dosimetry system concepts are described that will provide automated and instantaneous measurement of dose and particle spectra. Systems are proposed for measuring dose rate from cosmic radiation background to greater than 3600 rads/hr. Charged particle spectrometers, both internal and external to the spacecraft, are described for determining mixed field energy spectra and particle fluxes for both real time onboard and ground-based computer evaluation of the radiation hazard. Automated passive dosimetry systems consisting of thermoluminescent dosimeters and activation techniques are proposed for recording the dose levels for twelve or more crew members. This system will allow automatic onboard readout and data storage of the accumulated dose and can be transmitted to ground after readout or data records recovered with each crew rotation.

Carbon Ion Radiation Therapy With Concurrent Gemcitabine for Patients With Locally Advanced Pancreatic Cancer

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

Shinoto, Makoto, E-mail: shinoto@saga-himat.jp; Ion Beam Therapy Center, SAGA HIMAT Foundation, Tosu; Department of Clinical Radiology, Graduate School of Medical Sciences, Kyushu University, Fukuoka

Purpose: To determine, in the setting of locally advanced pancreatic cancer, the maximum tolerated dose of carbon ion radiation therapy (C-ion RT) and gemcitabine dose delivered concurrently and to estimate local effect and survival. Methods and Materials: Eligibility included pathologic confirmation of pancreatic invasive ductal carcinomas and radiographically unresectable disease without metastasis. Concurrent gemcitabine was administered on days 1, 8, and 15, and the dose levels were escalated from 400 to 1000 mg/m{sup 2} under the starting dose level (43.2 GyE) of C-ion RT. The dose levels of C-ion RT were escalated from 43.2 to 55.2 GyE at 12 fractions undermore » the fixed recommended gemcitabine dose determined. Results: Seventy-six patients were enrolled. Among the 72 treated patients, dose-limiting toxicity was observed in 3 patients: grade 3 infection in 1 patient and grade 4 neutropenia in 2 patients. Only 1 patient experienced a late grade 3 gastric ulcer and bleeding 10 months after C-ion RT. The recommended dose of gemcitabine with C-ion RT was found to be 1000 mg/m{sup 2}. The dose of C-ion RT with the full dose of gemcitabine (1000 mg/m{sup 2}) was safely increased to 55.2 GyE. The freedom from local progression rate was 83% at 2 years using the Response Evaluation Criteria in Solid Tumors. The 2-year overall survival rates in all patients and in the high-dose group with stage III (≥45.6 GyE) were 35% and 48%, respectively. Conclusions: Carbon ion RT with concurrent full-dose gemcitabine was well tolerated and effective in patients with unresectable locally advanced pancreatic cancer.« less

Radiation dose-rate meter using an energy-sensitive counter

DOEpatents

Kopp, Manfred K.

1988-01-01

A radiation dose-rate meter is provided which uses an energy-sensitive detector and combines charge quantization and pulse-rate measurement to monitor radiation dose rates. The charge from each detected photon is quantized by level-sensitive comparators so that the resulting total output pulse rate is proportional to the dose-rate.

Analysis of the dose-sparing effect of adjuvanted Sabin-inactivated poliovirus vaccine (sIPV).

PubMed

Li, Zhuofan; Ding, Wenting; Guo, Qi; Liu, Ze; Zhu, Zhe; Song, Shaohui; Li, Weidong; Liao, Guoyang

2018-03-30

Sabin-based inactivated poliovirus vaccine(sIPV) is gradually replacing live-attenuated oral polio vaccine(OPV). Sabin-inactivated poliovirus vaccine(sIPV) has played a vital role in reducing economic burden of poliomyelitis and maintaining appropriate antibody levels in the population. However, due to its high cost and limited manufacturing capacity, sIPV cannot reach its full potential for global poliovirus eradication in developing countries. Therefore, to address this situation, we designed this study to evaluate the dose-sparing effects of AS03, CpG oligodeoxynucleotides (CpG-ODN) and polyinosinic:polycytidylic acid (PolyI:C) admixed with sIPV in rats. Our results showed that a combination of 1/4-dose sIPV adjuvanted with AS03 or AS03 with BW006 provides a seroconversion rate similar to that of full-dose sIPV without adjuvant and that, this rate is 5-fold higher than that of 1/4-dose sIPV without adjuvant after the first immunization. The combination of AS03 or AS03 with BW006 as an adjuvant effectively reduced sIPV dose by at least 4-fold and induced both humoral and cellular immune responses. Therefore, our study revealed that the combination of AS03 or AS03 with BW006 is a promising adjuvant for sIPV development.

The biological impacts of ingested radioactive materials on the pale grass blue butterfly

NASA Astrophysics Data System (ADS)

Nohara, Chiyo; Hiyama, Atsuki; Taira, Wataru; Tanahara, Akira; Otaki, Joji M.

2014-05-01

A massive amount of radioactive materials has been released into the environment by the Fukushima Dai-ichi Nuclear Power Plant accident, but its biological impacts have rarely been examined. Here, we have quantitatively evaluated the relationship between the dose of ingested radioactive cesium and mortality and abnormality rates using the pale grass blue butterfly, Zizeeria maha. When larvae from Okinawa, which is likely the least polluted locality in Japan, were fed leaves collected from polluted localities, mortality and abnormality rates increased sharply at low doses in response to the ingested cesium dose. This dose-response relationship was best fitted by power function models, which indicated that the half lethal and abnormal doses were 1.9 and 0.76 Bq per larva, corresponding to 54,000 and 22,000 Bq per kilogram body weight, respectively. Both the retention of radioactive cesium in a pupa relative to the ingested dose throughout the larval stage and the accumulation of radioactive cesium in a pupa relative to the activity concentration in a diet were highest at the lowest level of cesium ingested. We conclude that the risk of ingesting a polluted diet is realistic, at least for this butterfly, and likely for certain other organisms living in the polluted area.

Effects of low dose ibogaine on subjective mood state and psychological performance.

PubMed

Forsyth, Bridget; Machado, Liana; Jowett, Tim; Jakobi, Hannah; Garbe, Kira; Winter, Helen; Glue, Paul

2016-08-02

Root bark from Tabernanthe iboga has been used traditionally in West Africa as a psychoactive substance in religious rituals. In smaller doses it is reported anecdotally to have stimulant properties. To evaluate the influence of a single 20mg ibogaine dose on psychological variables reflecting subjective mood state and a range of cognitive functions. 21 healthy male volunteers received single 20mg doses of ibogaine after 6 days pretreatment with double-blind paroxetine or placebo. We compared responses to a battery of psychometric tests and subjective mood ratings performed before and 2h after ibogaine dosing, and assessed relationships between changes in test scores and concentrations of active moiety (the sum of molar noribogaine and ibogaine concentrations). Psychological tests were chosen based on responsiveness to opioid and serotonergic ligands. Ibogaine had minimal influence on psychological tests and mood ratings. The ability to selectively ignore distracting spatial information showed some evidence of modulation; however because this effect was limited to the less challenging condition calls into question the reliability of this result. We were unable to identify stimulant effects after single 20mg doses of ibogaine. Future research is needed to confirm whether active moiety concentrations impact selective attention abilities while leaving other cognitive functions and mood state unaffected. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

The biological impacts of ingested radioactive materials on the pale grass blue butterfly.

PubMed

Nohara, Chiyo; Hiyama, Atsuki; Taira, Wataru; Tanahara, Akira; Otaki, Joji M

2014-05-15

A massive amount of radioactive materials has been released into the environment by the Fukushima Dai-ichi Nuclear Power Plant accident, but its biological impacts have rarely been examined. Here, we have quantitatively evaluated the relationship between the dose of ingested radioactive cesium and mortality and abnormality rates using the pale grass blue butterfly, Zizeeria maha. When larvae from Okinawa, which is likely the least polluted locality in Japan, were fed leaves collected from polluted localities, mortality and abnormality rates increased sharply at low doses in response to the ingested cesium dose. This dose-response relationship was best fitted by power function models, which indicated that the half lethal and abnormal doses were 1.9 and 0.76 Bq per larva, corresponding to 54,000 and 22,000 Bq per kilogram body weight, respectively. Both the retention of radioactive cesium in a pupa relative to the ingested dose throughout the larval stage and the accumulation of radioactive cesium in a pupa relative to the activity concentration in a diet were highest at the lowest level of cesium ingested. We conclude that the risk of ingesting a polluted diet is realistic, at least for this butterfly, and likely for certain other organisms living in the polluted area.

Impact of a Clinical Pharmacy Service on the Management of Patients in a Sickle Cell Disease Outpatient Center.

PubMed

Han, Jin; Bhat, Shubha; Gowhari, Michel; Gordeuk, Victor R; Saraf, Santosh L

2016-11-01

Ambulatory care clinical pharmacy services have expanded beyond primary care settings, but literature supporting the benefits of clinical pharmacy involvement with patients who have rare diseases such as sickle cell disease (SCD) is lacking. Hydroxyurea is the only agent approved by the U.S. Food and Drug Administration for the treatment of SCD; full benefit in controlling pain episodes and other complications is achieved through monitored escalation to a maximum tolerated dose. The primary objective of this analysis was to evaluate the impact of a newly implemented clinical pharmacy service on the management of patients with SCD. We performed a retrospective cross-sectional analysis of 385 adults with SCD who received care between January 1, 2014, and December 31, 2014, at a single Sickle Cell Outpatient Center that implemented a clinical pharmacy service in August 2013. Data were collected on hydroxyurea dose escalation, immunization completion rates, and health maintenance metrics (screening for nephropathy with microalbuminuria testing, retinopathy with annual retinal examinations, and pulmonary hypertension with echocardiography). The impact of the clinical pharmacy service on quality measurements was evaluated by using univariate and multivariate analyses. The number of pharmacist encounters, defined as a clinic visit when a clinical pharmacist interacted with a patient as documented in the medical records, was associated with an improved hydroxyurea dose escalation rate (odds ratio [OR] 1.48, 95% confidence interval [CI] 1.07-2.05, p=0.02). Immunization rates for the 23-valent pneumococcal polysaccharide vaccine, the 13-valent pneumococcal conjugate vaccine, and influenza vaccine were 66%, 47%, and 62%, respectively. The number of pharmacist encounters was associated with improved immunization completion rates (OR 1.38, 95% CI 1.17-1.62, p<0.001). Improved screening for microalbuminuria (OR 2.14, 95% CI 1.60-2.86, p<0.001) and sickle cell retinopathy (OR 1.16, 95% CI 1.00-1.35, p=0.05) were also associated with the number of pharmacist encounters. A new clinical pharmacy service implemented in managing a rare disease, SCD, was associated with an improved hydroxyurea dose escalation rate, immunization completion rates, and health maintenance metrics. © 2016 Pharmacotherapy Publications, Inc.

Randomized controlled trial of a dose consolidation program.

PubMed

Delate, Thomas; Fairman, Kathleen A; Carey, Shelly M; Motheral, Brenda R

2004-01-01

To evaluate the effectiveness and financial impact of a drug dose consolidation (optimization) program using letter intervention. This pilot program in a large, mid-Atlantic health plan utilized a randomized controlled trial research design. A review of adjudicated pharmacy claims records was performed monthly for 3 consecutive months from November 2002 through February 2003 to identify inefficient (i.e., >once-daily) regimens for any one of 68 dosage strengths of 37 single-source maintenance drugs with once-daily dosing recommendations. Prescribers who had prescribed one or more inefficient regimens were identified and randomized to one of the 2 intervention arms or a control arm. Prescribers in both intervention arms were sent personalized letters with information on their patients. inefficient regimens and suggested dose consolidation options. Patients of prescribers in one intervention arm received a complementary, patient-oriented letter. Pharmacy claims for patients in all arms were examined at 180 days after the date of the letter mailing for conversion to an efficient (once-daily) regimen. Financial modeling analysis calculated net savings as changes in pharmacy expenditures minus administrative costs. A total of 2,614 inefficient regimens, representing 6.7% of claims for the targeted medications, were identified. The rate of consolidation to a suggested dosing option was lower for the Physician Letter arm (7.3%) than for the Physician/Member Letter arm (10.2%) (P = 0.046). Both intervention arms had higher consolidation rates than the Control arm (3.9%) (P = 0.018 and P = 0.000, respectively.). Approximately 30% of the regimens in each study arm were never refilled after being targeted. Financial modeling indicated that a dose consolidation intervention could save 0.03 dollars to 0.07 dollars per member per month (PMPM) in 2003 dollars with full medication compliance but only 0.02 dollars to 0.03 dollars PMPM when savings were calculated with realistic, partial compliance rates. Subanalyses performed at the drug therapy class level revealed few opportunities to justify implementing a dose consolidation program. After taking into consideration program administrative costs, high rates of refill discontinuation, and dose consolidation that occurs naturally without intervention, the results indicated that a letter-based dose consolidation program did not appreciably decrease pharmacy expenditures.