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All sourcesNASA NTRSDOE OSTI
DOE OSTI2026

User’s Manual for RESRAD-RDD&IND Code Version 2: Vol. 2—User’s Guide for RESRAD-RDD&IND Code

Version 2.0 of the RESRAD-RDD&IND computer code is designed to support the implementation of protective action guides (PAGs) after a nuclear emergency incident including a radiological dispersal device (RDD) and/or an improvised nuclear device (IND) incident (EPA 2017). Eight different group types, addressing various decisions, are available for selection. The RESRAD-RDD&IND code calculates radiological doses, stay times, etc., for the selected group that the user wishes to focus on. (That is, the results for all the groups are not calculated simultaneously, and the input for those other groups do not matter, although some parameter values are shared between groups.) Version 2.0 has a user-friendly interface so that the RESRAD-RDD&IND code can be used with minimal training. For example, the user can select the major characteristics of the problem-event type, source term, and decision type from the left side of the interface and then calculate the results with the default assumptions for the exposure scenarios. More in-depth analysis would include specifying site-specific exposure scenario characteristics in the right side of the interface. The procedures for data entry and results viewing are self-explanatory. This is because common window maneuvering features and text instructions were incorporated in the interface design. General and context-specific help are available to aid users entering parameter values, as well. The RESRAD-RDD&IND computer code gives the user the option to select either an RDD or IND incident for analysis. For an RDD event analysis, 11 radionuclides (Am-241, Cf-252, Cm-244, Co-60, Cs-137, Ir-192, Po-210, Pu-238, Pu-239, Ra-226, and Sr-90) are included. These 11 radionuclides are the radionuclides most likely used for an RDD. More than 90 radionuclides can be selected for an IND event analysis. Initial default concentrations are provided for 44 radionuclides for a uranium-fueled IND event. These 44 radionuclides are those that would contribute significantly to the radiation dose associated with a uranium-fueled bomb detonation. The radionuclides generated from ingrowth of these 44 initial radionuclides are also automatically included in the analysis. Pu-239, Cs-134m, Ru-105, and Rb-89 and their progeny can be selected for analysis if they are detected and their concentrations are determined. This user’s guide, which is Volume 2 of the User’s Manual for RESRAD-RDD&IND Code Version 2, provides instructions to users on how to install the RESRAD-RDD&IND code, navigate the interface, and use the various features, including those discussed above, to set up an analysis and view/print the results in text outputs. Volume 1 of the User’s Manual for RESRAD-RDD&IND Code Version 2 (Yu et al. 2026), which contains descriptions of the methodology and theoretical basis for dose modeling and the mathematical equations implemented in the code, can be accessed and viewed through the Help menu in the code or can be downloaded from the RESRAD website (https://resrad.evs.anl.gov).

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2025

Implementation of the D1S Methodology for Shutdown Dose Rate Calculations in the OpenMC Monte Carlo Particle Transport Code

We present an implementation of the direct one-step (D1S) methodology for shutdown dose rate (SDR) calculations in the OpenMC Monte Carlo particle transport code. In addition to being the first fully open-source D1S implementation, it is also the first to require no ad hoc source code or nuclear data library modifications. The code can seamlessly switch between production of prompt and decay photons based on a user input parameter, and the decay data needed for decay photon generation are made available through a depletion chain file, which is already used for OpenMC’s built-in depletion/activation solver. A set of Python functions significantly eases the burden of computing and applying time correction factors needed to properly account for the time dependence of radionuclide activity. To assess the accuracy of the D1S implementation, SDR calculations have been carried out for three problems: a prism of iron irradiated by 14-MeV neutrons, the ITER port plug computational benchmark, and the Frascati Neutron Generator (FNG) ITER dose rate benchmark problem from the Shielding INtegral Benchmark Archive and Database (SINBAD). For each of these problems, comparisons were made to calculations using the rigorous two-step (R2S) method. The results on the iron prism problem illustrate how the D1S method achieves superior spatial resolution compared to the R2S method without the need for spatial discretization of the activation regions. The D1S and R2S results for the ITER port plug benchmark agree well with previously reported results in the literature. While the D1S results are 10% to 15% lower than the R2S results, this may be due to stochastic uncertainty and/or spatial discretization in the R2S calculations. On the FNG dose rate benchmark problem, the D1S method produces dose rate estimates that are within 4% of the dose rates predicted using a cell-based R2S workflow. The D1S estimates of the SDR are also in reasonable agreement with the experimental measurements and show the same basic trends that have been observed in previous works. A qualitative analysis of the execution time and uncertainty for the R2S and D1S workflows suggests that the D1S method would attain a higher figure of merit.

D1S method↗
DOE OSTI2011

Calculation of Residual Dose Around Small Objects Using Mu2e Target as an Example

The MARS15 code provides contact residual dose rates for relatively large accelerator and experimental components for predefined irradiation and cooling times. The dose rate at particular distances from the components, some of which can be rather small in size, is calculated in a post Monte-Carlo stage via special algorithms described elsewhere. The approach is further developed and described in this paper.

43 PARTICLE ACCELERATORS↗
DOE OSTI2016

SU-F-T-12: Monte Carlo Dosimetry of the 60Co Bebig High Dose Rate Source for Brachytherapy

Purpose: The purpose of this work is to obtain the dosimetry parameters in accordance with the AAPM TG-43U1 formalism with Monte Carlo calculations regarding the BEBIG 60Co high-dose-rate brachytherapy. The geometric design and material details of the source was provided by the manufacturer and was used to define the Monte Carlo geometry. Methods: The dosimetry studies included the calculation of the air kerma strength Sk, collision kerma in water along the transverse axis with an unbounded phantom, dose rate constant and radial dose function. The Monte Carlo code system that was used was EGSnrc with a new cavity code, which is a part of EGS++ that allows calculating the radial dose function around the source. The XCOM photon cross-section library was used. Variance reduction techniques were used to speed up the calculation and to considerably reduce the computer time. To obtain the dose rate distributions of the source in an unbounded liquid water phantom, the source was immersed at the center of a cube phantom of 100 cm3. Results: The obtained dose rate constant for the BEBIG 60Co source was 1.108±0.001 cGyh-1U-1, which is consistent with the values in the literature. The radial dose functions were compared with the values of the consensus data set in the literature, and they are consistent with the published data for this energy range. Conclusion: The dose rate constant is consistent with the results of Granero et al. and Selvam and Bhola within 1%. Dose rate data are compared to GEANT4 and DORZnrc Monte Carlo code. However, the radial dose function is different by up to 10% for the points that are notably near the source on the transversal axis because of the high-energy photons from 60Co, which causes an electronic disequilibrium at the interface between the source capsule and the liquid water for distances up to 1 cm.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2014

HDRMC, an accelerated Monte Carlo dose calculator for high dose rate brachytherapy with CT-compatible applicators

Purpose: To present a new accelerated Monte Carlo code for CT-based dose calculations in high dose rate (HDR) brachytherapy. The new code (HDRMC) accounts for both tissue and nontissue heterogeneities (applicator and contrast medium). Methods: HDRMC uses a fast ray-tracing technique and detailed physics algorithms to transport photons through a 3D mesh of voxels representing the patient anatomy with applicator and contrast medium included. A precalculated phase space file for the{sup 192}Ir source is used as source term. HDRM is calibrated to calculated absolute dose for real plans. A postprocessing technique is used to include the exact density and composition of nontissue heterogeneities in the 3D phantom. Dwell positions and angular orientations of the source are reconstructed using data from the treatment planning system (TPS). Structure contours are also imported from the TPS to recalculate dose-volume histograms. Results: HDRMC was first benchmarked against the MCNP5 code for a single source in homogenous water and for a loaded gynecologic applicator in water. The accuracy of the voxel-based applicator model used in HDRMC was also verified by comparing 3D dose distributions and dose-volume parameters obtained using 1-mm{sup 3} versus 2-mm{sup 3} phantom resolutions. HDRMC can calculate the 3D dose distribution for a typical HDR cervix case with 2-mm resolution in 5 min on a single CPU. Examples of heterogeneity effects for two clinical cases (cervix and esophagus) were demonstrated using HDRMC. The neglect of tissue heterogeneity for the esophageal case leads to the overestimate of CTV D90, CTV D100, and spinal cord maximum dose by 3.2%, 3.9%, and 3.6%, respectively. Conclusions: A fast Monte Carlo code for CT-based dose calculations which does not require a prebuilt applicator model is developed for those HDR brachytherapy treatments that use CT-compatible applicators. Tissue and nontissue heterogeneities should be taken into account in modern HDR brachytherapy planning.

61 RADIATION PROTECTION AND DOSIMETRY↗
DOE OSTI2016

Dosimetric quality, accuracy, and deliverability of modulated radiotherapy treatments for spinal metastases

Cancer often metastasizes to the vertebra, and such metastases can be treated successfully using simple, static posterior or opposed-pair radiation fields. However, in some cases, including when re-irradiation is required, spinal cord avoidance becomes necessary and more complex treatment plans must be used. This study evaluated 16 sample intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT) treatment plans designed to treat 6 typical vertebral and paraspinal volumes using a standard prescription, with the aim of investigating the advantages and limitations of these treatment techniques and providing recommendations for their optimal use in vertebral treatments. Treatment plan quality and beam complexity metrics were evaluated using the Treatment And Dose Assessor (TADA) code. A portal-imaging–based quality assurance (QA) system was used to evaluate treatment delivery accuracy, and radiochromic film measurements were used to provide high-resolution verification of treatment plan dose accuracy, especially in the steep dose gradient regions between each vertebral target and spinal cord. All treatment modalities delivered approximately the same doses and the same levels of dose heterogeneity to each planning target volume (PTV), although the minimum PTV doses in the vertebral plans were substantially lower than the prescription, because of the requirement that the plans meet a strict constraint on the dose to the spinal cord and cord planning risk volume (PRV). All plans met required dose constraints on all organs at risk, and all measured PTV-cord dose gradients were steeper than planned. Beam complexity analysis suggested that the IMRT treatment plans were more deliverable (less complex, leading to greater QA success) than the VMAT treatment plans, although the IMRT plans also took more time to deliver. The accuracy and deliverability of VMAT treatment plans were found to be substantially increased by limiting the number of monitor units (MU) per beam at the optimization stage, and thereby limiting beam modulation complexity. The VMAT arcs that were optimized with MU limitation had higher QA pass rates as well as higher modulation complexity scores (less complexity), lower modulation indices (less modulation), lower MU per beam, larger beam segments, and fewer small apertures than the VMAT arcs that were optimized without MU limitation. It is recommended that VMAT treatments for vertebral volumes, where the PTV abuts or surrounds the spinal cord, should be optimized with MU limitation. IMRT treatments may be preferable to the VMAT treatments, for dosimetry and deliverability reasons, but may be inappropriate for some patients because of their increased treatment delivery time.

61 RADIATION PROTECTION AND DOSIMETRY↗
DOE OSTI2020

A Study on Radionuclides Selection for DCGLs Development for Site Release of KRR Units 1 and 2 site in Korea - 20256

The selection of Derived Concentration Guideline Levels (DCGLs) in nuclear facilities decommissioning is important because they serve as criteria for site characterization and final status surveys. DCGLs should be derived for KAERI TRIGA Mark II and III research reactor site clearance and prior to the work, a radionuclides list for DCGLs consideration was created. Radionuclides selection for DCGLs was performed according to the procedure proposed by the US NRC based on the characterization survey related to the decommission site. By evaluating the dose contribution of each radionuclide using D and D computer code, radionuclides with a dose contribution fraction of 0.1% or more for the entire radionuclide were selected. As a result, the selected radionuclides were beta radionuclides H-3, C-14 and Sr-90 and gamma radionuclides Co-60, Cs-137, Eu-152 and Eu-154. The selected radionuclides can be presented for consultation with domestic regulatory agencies in the future and will be used as the technical base of DCGLs for the final status survey. (authors)

07 ISOTOPE AND RADIATION SOURCES↗
DOE OSTI2015

SU-E-T-238: Deriving Electron Contamination Spectra From Pure and Clinical Photon Beams

Purpose: To extract the electron contamination energy spectra for an Elekta Precise Linac, based on pure photon and measured clinical beam percentage depth dose data. And to include this as an additional source in isource 4 in DOSXYZnrc. Methods: A pure photon beam was simulated for the Linac using isource 4 in the DOSXYZnrc Monte Carlo (MC) code. Percentage depth dose (PDD) data were extracted afterwards for a range of field sizes (FS). These simulated dose data were compared to actual measured dose PDD data, with the data normalized at 10 cm depth. The resulting PDD data resembled the electron contamination depth dose. Since the dose fall-off is a strictly decreasing function, a method was adopted to derive the contamination electron spectrum. Afterwards this spectrum was used in a DOSXYZnrc MC simulation run to verify that the original electron depth dose could be replicated. Results: Various square aperture FS’s for 6, 8 and 15 megavolt (MV) photon beams were modeled, simulated and compared to their respective actual measured PDD data. As FS increased, simulated pure photon depth-dose profiles shifted deeper, thus requiring electron contamination to increase the surface dose. The percentage of electron weight increased with increase in FS. For a FS of 15×15 cm{sup 2}, the percentage electron weight is 0.1%, 0.2% and 0.4% for 6, 8 and 15 MV beams respectively. Conclusion: From the PDD results obtained, an additional electron contamination source was added to the photon source model so that simulation and measured PDD data could match within 2 % / 2 mm gamma-index criteria. The improved source model could assure more accurate simulations of surface doses. This research project was funded by the South African Medical Research Council (MRC) with funds from National Treasury under its Economic Competitiveness and Support package.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2014

SU-E-T-238: Monte Carlo Estimation of Cerenkov Dose for Photo-Dynamic Radiotherapy

Purpose: Estimation of Cerenkov dose from high-energy megavoltage photon and electron beams in tissue and its impact on the radiosensitization using Protoporphyrine IX (PpIX) for tumor targeting enhancement in radiotherapy. Methods: The GEPTS Monte Carlo code is used to generate dose distributions from 18MV Varian photon beam and generic high-energy (45-MV) photon and (45-MeV) electron beams in a voxel-based tissueequivalent phantom. In addition to calculating the ionization dose, the code scores Cerenkov energy released in the wavelength range 375–425 nm corresponding to the pick of the PpIX absorption spectrum (Fig. 1) using the Frank-Tamm formula. Results: The simulations shows that the produced Cerenkov dose suitable for activating PpIX is 4000 to 5500 times lower than the overall radiation dose for all considered beams (18MV, 45 MV and 45 MeV). These results were contradictory to the recent experimental studies by Axelsson et al. (Med. Phys. 38 (2011) p 4127), where Cerenkov dose was reported to be only two orders of magnitude lower than the radiation dose. Note that our simulation results can be corroborated by a simple model where the Frank and Tamm formula is applied for electrons with 2 MeV/cm stopping power generating Cerenkov photons in the 375–425 nm range and assuming these photons have less than 1mm penetration in tissue. Conclusion: The Cerenkov dose generated by high-energy photon and electron beams may produce minimal clinical effect in comparison with the photon fluence (or dose) commonly used for photo-dynamic therapy. At the present time, it is unclear whether Cerenkov radiation is a significant contributor to the recently observed tumor regression for patients receiving radiotherapy and PpIX versus patients receiving radiotherapy only. The ongoing study will include animal experimentation and investigation of dose rate effects on PpIX response.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2017

A Comparison of Select USDOE and USEPA Risk and Dose Assessment Tools Utilized at Two FUSRAP Projects - 17388

The US Army Corps of Engineers (USACE) utilizes several computer programs and models to conduct risk and dose assessments at Formerly Utilized Sites Remedial Action Program (FUSRAP) projects. In the past, the USACE has primarily relied on the US Department of Energy (USDOE)'s Argonne National Lab (ANL) RESidual Radioactivity (RESRAD) computer code for performing dose and risk assessments involving radiological contamination in onsite soils and the US Environmental Protection Agency (USEPA) Preliminary Remediation Goal (PRG) and Dose Compliance Calculator (DCC) for radiological contamination in ground water. Recent USEPA guidance requires use of USEPA calculators for all media at National Priority List sites, which includes some FUSRAP sites. The USACE recently utilized both RESRAD and the USEPA PRG and DCC calculators in assessments at two FUSRAP projects for all media in order to evaluate differences in the models and determine adjustments to potentially resolve differences. The two projects involve soil and groundwater assessments and address typical FUSRAP contaminants such as uranium, radium, thorium and their progeny. This paper discusses differences between the models, lessons learned, and methods used to address stakeholder and other concerns regarding these assessments. The paper's discussions are useful for anyone performing risk or dose assessments for radiological contamination and especially those using RESRAD and the PRG and DCC calculators. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
NASA NTRS1998

Design of the Experimental Exposure Conditions to Simulate Ionizing Radiation Effects on Candidate Replacement Materials for the Hubble Space Telescope

In this effort, experimental exposure times for monoenergetic electrons and protons were determined to simulate the space radiation environment effects on Teflon components of the Hubble Space Telescope. Although the energy range of the available laboratory particle accelerators was limited, optimal exposure times for 50 keV, 220 keV, 350 keV, and 500 KeV electrons were calculated that produced a dose-versus-depth profile that approximated the full spectrum profile, and were realizable with existing equipment. For the case of proton exposure, the limited energy range of the laboratory accelerator restricted simulation of the dose to a depth of .5 mil. Also, while optimal exposure times were found for 200 keV, 500 keV and 700 keV protons that simulated the full spectrum dose-versus-depth profile to this depth, they were of such short duration that the existing laboratory could not be controlled to within the required accuracy. In addition to the obvious experimental issues, other areas exist in which the analytical work could be advanced. Improved computer codes for the dose prediction- along with improved methodology for data input and output- would accelerate and make more accurate the calculational aspects. This is particularly true in the case of proton fluxes where a paucity of available predictive software appears to exist. The dated nature of many of the existing Monte Carlo particle/radiation transport codes raises the issue as to whether existing codes are sufficient for this type of analysis. Other areas that would result in greater fidelity of laboratory exposure effects to the space environment is the use of a larger number of monoenergetic particle fluxes and improved optimization algorithms to determine the weighting values.

Smith, L. Montgomery↗
DOE OSTI2016

SU-F-T-117: A Pilot Study of Organ Dose Reconstruction for Wilms Tumor Patients Treated with Radiation Therapy

Purpose: To reconstruct major organ doses for the Wilms tumor pediatric patients treated with radiation therapy using pediatric computational phantoms, treatment planning system (TPS), and Monte Carlo (MC) dose calculation methods. Methods: A total of ten female and male pediatric patients (15–88 months old) were selected from the National Wilms Tumor Study cohort and ten pediatric computational phantoms corresponding to the patient’s height and weight were selected for the organ dose reconstruction. Treatment plans were reconstructed on the computational phantoms in a Pinnacle TPS (v9.10) referring to treatment records and exported into DICOM-RT files, which were then used to generate the input files for XVMC MC code. The mean doses to major organs and the dose received by 50% of the heart were calculated and compared between TPS and MC calculations. The same calculations were conducted by replacing the computational human phantoms with a series of diagnostic patient CT images selected by matching the height and weight of the patients to validate the anatomical accuracy of the computational phantoms. Results: Dose to organs located within the treatment fields from the computational phantoms and the diagnostic patient CT images agreed within 2% for all cases for both TPS and MC calculations. The maximum difference of organ doses was 55.9 % (thyroid), but the absolute dose difference in this case was 0.33 Gy which was 0.96% of the prescription dose. The doses to ovaries and testes from MC in out-of-field provided more discrepancy (the maximum difference of 13.2% and 50.8%, respectively). The maximum difference of the 50% heart volume dose between the phantoms and the patient CT images was 40.0%. Conclusion: This study showed the pediatric computational phantoms are applicable to organ doses reconstruction for the radiotherapy patients whose three-dimensional radiological images are not available.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2019

ENHANCEMENTS IN THE TECHA RIVER DOSIMETRY SYSTEM: TRDS-2016D CODE FOR RECONSTRUCTION OF DETERMINISTIC ESTIMATES OF DOSE FROM ENVIRONMENTAL EXPOSURES

Waterborne releases to the Techa River from the Mayak plutonium facility in Russia during 1949–1956 resulted in significant doses to persons living downstream. The dosimetry system TRDS-2016D has been developed which provides individual doses of external and internal exposure for the members of the Techa River Cohort (TRC) and other persons, who were exposed to releases of radioactive material to the Southern Urals. The results of computation of individual doses absorbed in red bone marrow and extra-skeletal tissues for the TRC members (29,647 persons) are presented, which are based on residence histories on the contaminated Techa River and the East Urals Radioactive Trace (EURT) which was formed in 1957 as a result of the Kyshtym Accident. Available 90Sr-body-burden measurements and available information on individual household locations have been used for refinement of individual dose estimates. TRDS-2016D-based dose estimates will be used for verification of risk of low-dose-rate effects of ionizing radiation in the TRC.

dose reconstruction, environmental contamination, ↗
DOE OSTI2012

Accuracy of the electron transport in mcnp5 and its suitability for ionization chamber response simulations: A comparison with the egsnrc and penelope codes

Purpose: In this work, accuracy of the mcnp5 code in the electron transport calculations and its suitability for ionization chamber (IC) response simulations in photon beams are studied in comparison to egsnrc and penelope codes. Methods: The electron transport is studied by comparing the depth dose distributions in a water phantom subdivided into thin layers using incident energies (0.05, 0.1, 1, and 10 MeV) for the broad parallel electron beams. The IC response simulations are studied in water phantom in three dosimetric gas materials (air, argon, and methane based tissue equivalent gas) for photon beams ({sup 60}Co source, 6 MV linear medical accelerator, and mono-energetic 2 MeV photon source). Two optional electron transport models of mcnp5 are evaluated: the ITS-based electron energy indexing (mcnp5{sub ITS}) and the new detailed electron energy-loss straggling logic (mcnp5{sub new}). The electron substep length (ESTEP parameter) dependency in mcnp5 is investigated as well. Results: For the electron beam studies, large discrepancies (>3%) are observed between the mcnp5 dose distributions and the reference codes at 1 MeV and lower energies. The discrepancy is especially notable for 0.1 and 0.05 MeV electron beams. The boundary crossing artifacts, which are well known for the mcnp5{sub ITS}, are observed for the mcnp5{sub new} only at 0.1 and 0.05 MeV beam energies. If the excessive boundary crossing is eliminated by using single scoring cells, the mcnp5{sub ITS} provides dose distributions that agree better with the reference codes than mcnp5{sub new}. The mcnp5 dose estimates for the gas cavity agree within 1% with the reference codes, if the mcnp5{sub ITS} is applied or electron substep length is set adequately for the gas in the cavity using the mcnp5{sub new}. The mcnp5{sub new} results are found highly dependent on the chosen electron substep length and might lead up to 15% underestimation of the absorbed dose. Conclusions: Since the mcnp5 electron transport calculations are not accurate at all energies and in every medium by general clinical standards, caution is needed, if mcnp5 is used with the current electron transport models for dosimetric applications.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2014

On the suitability of ultrathin detectors for absorbed dose assessment in the presence of high-density heterogeneities

Purpose: The aim of this study was to evaluate the suitability of several detectors for the determination of absorbed dose in bone. Methods: Three types of ultrathin LiF-based thermoluminescent dosimeters (TLDs)—two LiF:Mg,Cu,P-based (MCP-Ns and TLD-2000F) and a{sup 7}Li-enriched LiF:Mg,Ti-based (MTS-7s)—as well as EBT2 Gafchromic films were used to measure percentage depth-dose distributions (PDDs) in a water-equivalent phantom with a bone-equivalent heterogeneity for 6 and 18 MV and a set of field sizes ranging from 5×5 cm{sup 2} to 20×20 cm{sup 2}. MCP-Ns, TLD-2000F, MTS-7s, and EBT2 have active layers of 50, 20, 50, and 30 μm, respectively. Monte Carlo (MC) dose calculations (PENELOPE code) were used as the reference and helped to understand the experimental results and to evaluate the potential perturbation of the fluence in bone caused by the presence of the detectors. The energy dependence and linearity of the TLDs’ response was evaluated. Results: TLDs exhibited flat energy responses (within 2.5%) and linearity with dose (within 1.1%) within the range of interest for the selected beams. The results revealed that all considered detectors perturb the electron fluence with respect to the energy inside the bone-equivalent material. MCP-Ns and MTS-7s underestimated the absorbed dose in bone by 4%–5%. EBT2 exhibited comparable accuracy to MTS-7s and MCP-Ns. TLD-2000F was able to determine the dose within 2% accuracy. No dependence on the beam energy or field size was observed. The MC calculations showed that a50 μm thick detector can provide reliable dose estimations in bone regardless of whether it is made of LiF, water or EBT’s active layer material. Conclusions: TLD-2000F was found to be suitable for providing reliable absorbed dose measurements in the presence of bone for high-energy x-ray beams.

60 APPLIED LIFE SCIENCES↗
NASA NTRS1973

DOPEX-1D2C: A one-dimensional, two-constraint radiation shield optimization code

A one-dimensional, two-constraint radiation sheild weight optimization procedure and a computer program, DOPEX-1D2C, is described. The DOPEX-1D2C uses the steepest descent method to alter a set of initial (input) thicknesses of a spherical shield configuration to achieve a minimum weight while simultaneously satisfying two dose-rate constraints. The code assumes an exponential dose-shield thickness relation with parameters specified by the user. Code input instruction, a FORTRAN-4 listing, and a sample problem are given. Typical computer time required to optimize a seven-layer shield is less than 1/2 minute on an IBM 7094.

Lahti, G. P.↗
DOE OSTI2014

SU-E-CAMPUS-I-03: Dosimetric Comparison of the Hypoxia Agent Iodoazomycin Arabinoside (IAZA) Labeled with the Radioisotopes I-123, I-131 and I-124

Purpose: To compare the radiation dose to normal organs from the radio-iodinated, hypoxia-binding radiosensitizer iodoazomycin arabinoside (IAZA) for three different isotopes of iodine. Methods: Dosimety studies with normal volunteers had been carried out with [{sup 123}I]IAZA, a drug binding selectively to hypoxic sites. Two other isotopes of iodine, {sup 131}I and {sup 124}I, offer the opportunity to use IAZA as an agent for radioisotope therapy and as an imaging tracer for Positron Emission Tomography. Radioisotope dosimetry for {sup 131}I and {sup 124}I was performed by first deriving from the [{sup 123}I]IAZA studies biological uptake and excretion data. The cumulated activities for {sup 131}I or {sup 124}I where obtained by including their half-lives when integrating the biological data and then extrapolating to infinite time points considering a) physical decay only or b) physical and biological excretion. Doses were calculated using the Medical Internal Radiation Dose (MIRD) schema (OLINDA1.1 code, Vanderbilt 2007). Results: Compared to {sup 123}I, organ doses were elevated on average by a factor 6 and 9 for {sup 131}I and {sup 124}I, respectively, if both physical decay and biological excretion were modeled. If only physical decay is considered, doses increase by a factor 18 ({sup 131}I) and 19 ({sup 124}I). Highest organ doses were observed in intestinal walls, urinary bladder and thyroid. Effective doses increased by a factor 11 and 14 for {sup 131}I and {sup 124}I, respectively, if biological and physical decay are present. Purely physical decay yields a 23-fold increase over {sup 123}I for both, {sup 131}I and {sup 124}I. Conclusion: Owing to the significant dose increase, caused by their longer half life and the approximately 10 times larger electronic dose deposited in tissue per nuclear decay, normal tissue doses of IAZA labeled with {sup 131}I and {sup 124}I need to be carefully considered when designing imaging and therapy protocols for clinical trials. Effective blocking of iodine uptake in the thyroid is essential. Alberta Innovates - Health Solutions (AIHS) and Canadian Institutes of Health Research (CIHR)

60 APPLIED LIFE SCIENCES↗