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All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Reviewing MACCS Capabilities for Modeling Variable Physiochemical Forms

Multiple physical and chemical forms of a given radionuclide may be released in the event of a nuclear accident. Given that variable forms of an isotope may elicit changes in how that isotope moves through the environment and ultimately impacts human receptors, it is pertinent to understand how nuclear accident consequence models, such as MACCS, account for variable forms. This report documents a review of MACCS modeling capabilities for variability in radionuclide chemical and physical forms. This review centers on the current state-of-practice for dosimetry and deposition modeling of varying radionuclide forms to understand how consistent existing MACCS capabilities are with state of practice. This analysis is also used to inform potential MACCS model upgrades. MACCS conceptual models along with dosimetry and deposition related practices are discussed. Recommendations and suggestions for model improvements are posited.

07 ISOTOPE AND RADIATION SOURCES↗
DOE OSTI2026

ACRRF High-Bay Dose Calculations using MCNP (Part A)

Analytical tools and models have been developed as a starting point for directly assessing dose in the Annular Core Research Reactor Facility (ACRRF) due to reactor operation. Key results include peak dose along the Central Cavity (CC) centerline (beamline) at the cavity level, dose throughout the High-Bay (HB), and dose on the facility roof for partially-shielded reactor operation where the 4” insert is removed from the CC Shield Plug (SP). Model results in the beamline are benchmarked against measured doses from passive dosimetry evaluations. Personnel total (neutron and gamma) dose in the ACRRF HB is calculated using Monte Carlo N-Particle (MCNP). Various CC and SP configurations are analyzed, including unshielded (no SP) and partially shielded (SP installed but 4” insert removed). Novel application of Variance Reduction (VR) techniques, namely the Surface Source Write (SSW) and Surface Source Read (SSR) capabilities in MCNP, enable impressive resolution (in a Monte Carlo modeling sense) of dose throughout much the facility. The VR techniques reduce stochastic error for challenging tallies, with more advanced techniques explored in the companion to this report (Part B) [1]. Supplementary studies (including a verification analysis) and pedagogic evaluations in Part B involve neutron spectra, angular distributions, and the dose impact of facility characteristics. With the SP 4” insert removed and the Lead-Boron (44”) Bucket (LB–44) in the reactor cavity, Total Effective Dose (TED) within the CC beamline is ≈140 rem per 300 MJ of reactor yield (or 3900 rem per hour at 100% Steady-State (SS) power). With no SP (unshielded) and a Free-Field (FF) cavity, TED within the beamline is ≈610 rem per 300 MJ (or 17000 rem per hour at 100% SS power). Due to the predicted collimation of radiation by the reactor pool (and partial SP, if present), beamline dose is much greater than the scattered radiation field surrounding the cavity and reactor tank. Comparisons are made to beamline dosimetry measurements to validate the model. Model predictions agree reasonably well (⪅10%) with measured quantities of neutron fluence, gamma fluence, and spectral metrics. Away from the beamline, comparisons made to previous dose measurements in the HB agreement within an order of magnitude.

61 RADIATION PROTECTION AND DOSIMETRY↗
DOE OSTI2013

Iron Oxide Nanoparticle Agglomeration Influences Dose-Rates and Modulates Oxidative Stress Mediated Dose-Response Profiles In Vitro

Spontaneous agglomeration of engineered nanoparticles (ENPs) is a common problem in cell culture media which can confound interpretation of in vitro nanotoxicity studies. The authors created stable agglomerates of iron oxide nanoparticles (IONPs) in conventional culture medium, which varied in hydrodynamic size (276 nm-1.5 μm) but were composed of identical primary particles with similar surface potentials and protein coatings. Studies using C10 lung epithelial cells show that the dose rate effects of agglomeration can be substantial, varying by over an order of magnitude difference in cellular dose in some cases. Quantification by magnetic particle detection showed that small agglomerates of carboxylated IONPs induced greater cytotoxicity and redox-regulated gene expression when compared with large agglomerates on an equivalent total cellular IONP mass dose basis, whereas agglomerates of amine-modified IONPs failed to induce cytotoxicity or redox-regulated gene expression despite delivery of similar cellular doses. Dosimetry modelling and experimental measurements reveal that on a delivered surface area basis, large and small agglomerates of carboxylated IONPs have similar inherent potency for the generation of ROS, induction of stress-related genes and eventual cytotoxicity. The results suggest that reactive moieties on the agglomerate surface are more efficient in catalysing cellular ROS production than molecules buried within the agglomerate core. Because of the dynamic, size and density-dependent nature of ENP delivery to cells in vitro, the biological consequences of agglomeration are not discernible from static measures of exposure concentration (μg/ml) alone, highlighting the central importance of integrated physical characterisation and quantitative dosimetry for in vitro studies. The combined experimental and computational approach provides a quantitative framework for evaluating relationships between the biocompatibility of nanoparticles and their physical and chemical characteristics.

agglomeration↗
DOE OSTI2015

Multipurpose epithermal neutron beam on new research station at MARIA research reactor in Swierk-Poland

MARIA reactor is an open-pool research reactor what gives the chance to install uranium fission converter on the periphery of the core. It could be installed far enough not to induce reactivity of the core but close enough to produce high flux of fast neutrons. Special design of the converter is now under construction. It is planned to set the research stand based on such uranium converter in the near future: in 2015 MARIA reactor infrastructure should be ready (preparation started in 2013), in 2016 the neutron beam starts and in 2017 opening the stand for material and biological research or for medical training concerning BNCT. Unused for many years, horizontal channel number H2 at MARIA research rector in Poland, is going to be prepared as a part of unique stand. The characteristics of the neutron beam will be significant advantage of the facility. High flux of neutrons at the level of 2x10{sup 9} cm{sup -2}s{sup -1} will be obtainable by uranium neutron converter located 90 cm far from the reactor core fuel elements (still inside reactor core basket between so called core reflectors). Due to reaction of core neutrons with converter U{sub 3}Si{sub 2} material it will produce high flux of fast neutrons. After conversion neutrons will be collimated and moderated in the channel by special set of filters and moderators. At the end of H2 channel i.e. at the entrance to the research room neutron energy will be in the epithermal energy range with neutron intensity at least at the level required for BNCT (2x10{sup 9} cm{sup -2}s{sup -1}). For other purposes density of the neutron flux could be smaller. The possibility to change type and amount of installed filters/moderators which enables getting different properties of the beam (neutron energy spectrum, neutron-gamma ratio and beam profile and shape) is taken into account. H2 channel is located in separate room which is adjacent to two other empty rooms under the preparation for research laboratories (200 m2). It is planned to create fully equipped complex facility possible to perform various experiments on the intensive neutron beam. Epithermal neutron beam enables development across the full spectrum of materials research for example shielding concrete tests or electronic devices construction improvement. Due to recent reports on the construction of the accelerator for the Boron Neutron Capture Therapy (BNCT) it has the opportunity to become useful and successful method in the fight against brain and other types of cancers not treated with well known medical methods. In Europe there is no such epithermal neutron source which could be used throughout the year for training and research for scientist working on BNCT what makes the stand unique in Europe. Also our research group which specializes in mixed radiation dosimetry around nuclear and medical facilities would be able to carry out research on new detectors and methods of measurements for radiological protection and in-beam (therapeutic) dosimetry. Another group of scientists from National Centre for Nuclear Research, where MARIA research reactor is located, is involved in research of gamma detector systems. There is an idea to develop Prompt-gamma Single Photon Emission Computed Tomography (Pg- SPECT). This method could be used as imaging system for compounds emitting gamma rays after nuclear reaction with thermal neutrons e.g. for boron concentration in BNCT. Inside the room, where H2 channel is located, there is another horizontal channel - H1 which is also unused. Simultaneously with the construction of the H2 stand it will be possible to create special pneumatic horizontal mail inside the H1 channel for irradiation material samples in the vicinity of the core i.e. in the distal part of the H1 channel. It might expand the scope of research at the planned neutron station. Secondly it is planned to equip both stands with moveable positioning system, video system and facilities to perform animal experiments (anaesthesia, vital signs control, imaging devices, positioning). These all above make constructed station unique in the world (uranium fission converter-based beam) and the only one of such intense neutron beam in the Europe. Moreover implementation of the station would allow the development of research on a number of issues for researchers from all over the Europe. One of very important advantages of the station is undisturbed exploitation of the reactor and other vertical and horizontal channels. MARIA reactor operates 6000 hours per year and that amount of time will be achievable for research on the neutron station. It have to be underlined that new neutron station will work parallel to all another ventures. (authors)

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗
DOE OSTI2019

Evaluation of Low-cost, Full HD, CMOS Cameras for Use in the Calcine Retrieval Project - 19530

This paper describes results from radiation testing conducted on low-cost, commercial off-the-shelf, full high-definition (HD) resolution (1920 x 1080 p), complementary metal-oxide-semiconductor (CMOS) camera sensors. The purpose of the testing was to evaluate the sensors' suitability for use in the Calcine Retrieval Project by determining their image quality and life expectancy while operating in an ionizing radiation field of 20.0 Gy/h. The two camera sensors tested were the Axis FA1105 and Axis FA1125. These commercial camera sensors were designed for retail security surveillance and have no radiation-hardened (rad-hard) components. In addition to radiation testing, the sensors' field-of-view, resolution, and low-light image quality were tested at several target distances to ensure they meet project requirements. Testing was divided into two phases. During Phase 1, four FA1105 sensors and four FA1125 sensors were tested simultaneously without any shielding in radiation fields of 25.5 Gy/h and 49.3 Gy/h. In Phase 2, three FA1105 and five FA1125 sensors were shielded by 22.2 mm of lead and tested simultaneously in radiation fields of 26.8 Gy/h, 52.3 Gy/h, 143.0 Gy/h, 200.7 Gy/h, 404.6 Gy/h, and 2,317.5 Gy/h. Dose rate values were established using film dosimetry readings. Apertures in the shielding allowed for a 40-degree field of view while shielding all parts of the sensor except for directly in front of the CMOS sensor array. All testing was conducted at the Idaho Accelerator Center in Pocatello, Idaho, using a 450 keV X-ray generator. Sensor images were automatically captured at regular intervals throughout the testing for qualitative evaluation by the test team. Film dosimetry was placed near the sensors to record actual dose totals. The 450 keV setting generates X-ray radiation with an energy level close to the primary gamma energy level produced by the Cesium-137 isotope in the calcine, which is 662 keV. Results from Phase 1 indicate the sensors failed at an average cumulative dose of 226.3 Gy. For a given 20.0 Gy/h field this results in a mean time to failure (MTTF) of 11.3 hours. Recorded images from all sensors showed minimal image degradation due to radiation-induced noise. When the sensors finally failed, the failure mode was an abrupt loss of video. The image went black suggesting some other component in the sensor head besides the CMOS sensor array was responsible for the failure. During a portion of Phase 1 testing, a commercial, rad-hard camera was irradiated in the 25.5 Gy/h field along with the eight Axis FA series sensors. Image quality from the FA series sensors significantly outperformed the image quality of the rad-hard camera in radiation-induced noise tolerance, image resolution, and dynamic range. During Phase 2 testing, all sensors produced excellent images in radiation fields as high as 404.6 Gy/h. One FA1125 sensor was tested at the highest dose rate of 2,317.5 Gy/h. At this dose rate, the image was color shifted towards red and contained a significant amount radiation-induced noise. The sensor did not fail and was producing usable imagery after one hour, at which time the test was ended due to allotted beam-time at the test facility. Eighteen hours after X-rays were shut off, the sensor image returned to normal color and all eight sensors continued to operate without any visible, permanent image degradation. For Phase 2 testing, it was not possible to establish a MTTF since none of the shielded sensors failed during the allotted test time. However, given the highest cumulative dose of 4,142.1 Gy received by a shielded FA1125 sensor, a minimum life expectancy of 207 hours (8.6 days) is predicted while operating in a 20.0 Gy/h field. Test results indicate the radiation tolerance of the FA series sensor's CMOS array, along with the small form factor, full HD image quality, wide dynamic range, and Ethernet standard makes it suitable for short-term use in monitoring and visually documenting waste remediation efforts for the Calcine Retrieval Project at the INL. The sensor's low-cost of about $140 US, compared to commercial rad-hard cameras costing between $5,000 and $7,000 US each, allow them to be used as an affordable, disposable resource for many short-duration, radioactive waste remediation efforts where decontamination of an expensive, commercial rad-hard camera is undesirable or not possible. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2020

Analysis of Exposure during Transportation of Waste to the Nevada National Security Site (NNSS) - 20445

Safety is a priority for the U.S. Department of Energy (DOE) Environmental Management (EM) Nevada Program. This commitment to safety is integrated into requirements and work procedures at DOE sites across the U.S. that generate low-level radioactive waste, mixed low-level radioactive waste, and classified waste that is transported to the Nevada National Security Site (NNSS) for permanent disposal. Generators of this waste are responsible for ensuring it is packaged and transported in a safe and compliant manner. These generators and their contracted commercial carriers must comply with U.S. Department of Transportation (DOT) regulations; the Nevada National Security Site Waste Acceptance Criteria (NNSSWAC); and other applicable federal, state, and local regulations and requirements. This includes packaging and shipping the waste to meet DOT regulatory radiation dose limits to ensure public safety during transportation. NNSS waste generators have a solid safety record for complying with these stringent regulations as demonstrated by the fact that no shipments exceeding DOT dose rate limits were received at the NNSS Area 5 Radioactive Waste Management Complex (RWMC) during FY 2014 through FY 2018. A 2005 study conducted by the Desert Research Institute validated shipments to the NNSS comply with DOT radiation dose limits. In response to recent Nevada stakeholder requests for an updated study, an analysis was conducted to verify and provide evidence that the public continues to be safe from exposure to radioactive waste shipment to the NNSS. Radiation exposure from radioactive waste shipments in transit to the NNSS was evaluated. Three studies were performed: 1. Confirm compliance of waste shipments to the DOT radiation limits using dose rate surveys taken at the generator site and at the disposal site. 2. Estimate the dose to the public from waste shipments using the dosimetry results for disposal site personnel by comparing time of exposure for various individuals/scenarios. 3. Estimate the truck driver dose using the receipt dose rate surveys and time of exposure, and from dosimetry results. Study 1 confirmed compliance with the DOT dose rate limits for a sample of waste shipments (123 of 1,038) received during fiscal year (FY) 2017. Study 2 showed that the average annual radiation equivalent dose for disposal site personnel during FY 2017 was approximately 6.7% [0.415 mSv (41.5 millirem)] of the annual average dose that a person living in the U.S. receives from all sources [6.2 mSv (620 mrem)]. Maximum dose to a member of the public, a person resting/sleeping in an adjacent truck at a rest area to a waste shipment, was 0.0166 mSv (1.66 mrem), which is less than the dose received from a person taking a round trip from the east coast to the west coast of the continental U.S. on an airplane [0.07 mSv (7 mrem) per round trip]. Study 3 showed that the truck driver who made the most shipments of radioactive waste to the NNSS, who drove the most hours (estimated time of exposure 2,520 hours), during FY 2017 had a total dose of 0.15 mSv (15 mrem), which was obtained from their personal dosimeter. The annual dose recorded for disposal site personnel, the dose estimates for the public, and the truck driver dose were all a small percentage of the average radiation dose a person receives from all sources (e.g., background and medical radiation). At these levels, risk should only be described qualitatively. Radiation exposure from radioactive waste shipments to the NNSS were shown to be compliant with the DOT dose rate limits, safe, and very low (i.e., within background levels). (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2017

Demonstration of a Correlation between Tumor Absorbed Dose and Response in Several Pediatric Tumor Xenografts Treated with Radioiodinated CLR1404 Alkyl-Phospholipid Ether

Radionuclide therapy combines the specificity of cancer cell targeting with the well-known cytotoxic effects of ionizing radiation. It has the potential to simultaneously eradicate both the primary tumor site as well as the metastatic extent of the disease throughout the body. Radionuclide therapy in the form of {sup 131}Imetaiodobenzylguanidine ({sup 131}I-MIBG) has been used for several years to treat pediatric patients with advanced forms of neuroblastoma. {sup 131}I-MIBG treatments have improved palliation and progression-free survival rates in predominantly relapsed and refractory patients who have already endured an extensive chemotherapy regimen. MIBG is selectively taken up by an active transport mechanism in only neuroblastoma cells, limiting its applicability to other pediatric cancer types and additional radionuclide therapy options are needed. Several preclinical and clinical trials have shown selective in vitro uptake of {sup 131}I-CLR1404 in pediatric cancer cell lines. The focus of this work was to perform mouse-specific Monte Carlo-based dosimetry in several pediatric cancer xenografts being treated with {sup 131}I-CLR1404. Mouse-specific Monte Carlo-based dosimetry in radionuclide therapy can offer additional insight on the efficacy of new radiopharmaceuticals in organs and tumor volumes. In addition, this work demonstrates a clear dose-response relationship in these models.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2014

Aircrew, Cancer and Probability of Causation - Paper 60

Aircrew are radiation workers who normally are not provided with dosimetry. The Energy Employees Occupational Illness Compensation Policy Act (EEOICPA) established an important legal precedent that fundamentally changed employer liability for companies that expose workers to radiation. We have applied the method used by EEOICPA (Interactive Radio Epidemiological Program (IREP)) to cancers found in excess in published epidemiological studies of aircrew. Our results show that from 4 to 8 of the 12 cancers reported in the literature in typical aircrew may be compensable using EEOICPA methods. The other cancers may be compensable as well, given an unusual flight career with greater exposures than typical. Our research demonstrates there are cancers that have a 50% POC at annual exposures within the range of those asserted by the FAA for aircrew. The FAA currently estimates aircrew annual exposure as up to 6 mSv from GCR alone. While dosimetry is urgently needed for existing aircrew, historical dose reconstructions will be needed to address POC for aircrew diagnosed with a radiogenic cancer. (authors)

61 RADIATION PROTECTION AND DOSIMETRY↗
DOE OSTI2024

Preliminary analysis of TREAT free-field experiments using OpenMC

This work analyses activation calculations for dosimetry materials during a steady-state irradiation in the Transient Reactor Test (TREAT) reactor core. Hence, we developed a workflow based on the Monte Carlo code OpenMC alongside a custom depletion solver. The irradiation-induced activity as a function of time is computed, and several sensitivity studies are performed to evaluate uncertainty. This study has shown activity computations are sensitive to flux amplitude, irradiation time, atoms quantity and microscopic cross sections. Stochastic uncertainties have been propagated to evaluate the activity uncertainty for each dosimetry material. Most uncertainties are below our target of 3%, which demonstrates OpenMC as a powerful predictive and analysis tool. The precise results obtained through this newly developed computation scheme will be used in future experiments to characterize quantities of interest when operating the TREAT reactor in new configurations.

61 - RADIATION PROTECTION AND DOSIMETRY↗
DOE OSTI2015

ANALYSIS OF EPR AND FISH STUDIES OF RADIATION DOSES IN PERSONS WHO LIVED IN THE UPPER REACHES OF THE TECHA RIVER

Waterborne radioactive releases into the Techa River from the Mayak Production Association in Russia during 1949–1956 resulted in significant doses to about 30,000 persons who lived in downstream settlements. The residents were exposed to internal and external radiation. Two methods for reconstruction of the external dose are considered in this paper, electron paramagnetic resonance (EPR) measurements of teeth and fluorescence in situ hybridization (FISH) measurements of chromosome translocations in circulating lymphocytes. The main issue in the application of the EPR and FISH methods for reconstruction of the external dose for the Techa Riverside residents was strontium radioisotopes incorporated in teeth and bones that served as a source of confounding local exposures. In order to estimate and subtract doses from incorporated 89,90Sr, the EPR and FISH assays were supported by measurements of 90Sr-body burdens and estimates of 90Sr concentrations in dental tissues by the luminescence method. The resulting dose estimates derived from EPR and FISH measurements for residents of the upper Techa River were found to be consistent: the mean values vary from 510 – 550 mGy for the villages located close to the site of radioactive release to 130 – 160 mGy for the more distant villages. The upper bound of individual estimates for both methods is equal to 2.2 – 2.3 Gy. The EPR- and FISH-based dose estimates were compared with the doses calculated for the donors using the Techa River Dosimetry System (TRDS). The TRDS external dose assessments were based on the data on contamination of the Techa River floodplain, simulation of ai r kerma above the contaminated soil, age-dependent life-styles and individual residence histories. For correct comparison TRDS-based doses were calculated from two sources: external exposure from the contaminated environment and internal exposure from 137Cs incorporated in donors’ soft tissues. The TRDS-based absorbed doses in tooth enamel and muscle were in agreement with with EPR- and FISH-based estimates within uncertainty bounds. Basically, the agreement between the estimates has confirmed the validity of external doses calculated with the Techa River Dosimetry System.

dose reconstruction↗
DOE OSTI2018

Retrospective neutron spectrum determination of a (30 MeV D, Be) source using the multi-foil activation technique and STAYSL-PNNL [Characterization of neutron spectra from a (30 MeV d, Be) source using the multi-foil activation technique]

Retrospective characterization of a (30 MeV D, Be) neutron source was performed employing multi-foil activation and STAYSL-PNNL. Experimental reaction rates were calculated from gamma spectroscopy measurements of irradiated foils and MCNP provided the guess spectrum. Adjusted spectra were evaluated through activation calculations for a stainless-steel target using FISPACT-II. Adjusted spectra showed limited dependence on the dosimetry reactions and provided minor improvements in activation calculations. Omitting reflected neutrons in the guess spectrum generated poor activation results and the limited number of dosimetry reactions introduced doubt in the adjusted spectra. Furthermore, a dedicated neutron spectrometry experiment and a more detailed simulation is required.

42 ENGINEERING↗
DOE OSTI2016

A Comparative Evaluation of Normal Tissue Doses for Patients Receiving Radiation Therapy for Hodgkin Lymphoma on the Childhood Cancer Survivor Study and Recent Children's Oncology Group Trials

Purpose: Survivors of pediatric Hodgkin lymphoma (HL) are recognized to have an increased risk of delayed adverse health outcomes related to radiation therapy (RT). However, the necessary latency required to observe these late effects means that the estimated risks apply to outdated treatments. We sought to compare the normal tissue dose received by children treated for HL and enrolled in the Childhood Cancer Survivor Study (CCSS) (diagnosed 1970-1986) with that of patients treated in recent Children's Oncology Group (COG) trials (enrolled 2002-2012). Methods and Materials: RT planning data were obtained for 50 HL survivors randomly sampled from the CCSS cohort and applied to computed tomography planning data sets to reconstruct the normal tissue dosimetry. For comparison, the normal tissue dosimetry data were obtained for all 191 patients with full computed tomography–based volumetric RT planning on COG protocols AHOD0031 and AHOD0831. Results: For early-stage patients, the mean female breast dose in the COG patients was on average 83.5% lower than that for CCSS patients, with an absolute reduction of 15.5 Gy. For advanced-stage patients, the mean breast dose was decreased on average by 70% (11.6 Gy average absolute dose reduction). The mean heart dose decreased on average by 22.9 Gy (68.6%) and 17.6 Gy (56.8%) for early- and advanced-stage patients, respectively. All dose comparisons for breast, heart, lung, and thyroid were significantly lower for patients in the COG trials than for the CCSS participants. Reductions in the prescribed dose were a major contributor to these dose reductions. Conclusions: These are the first data quantifying the significant reduction in the normal tissue dose using actual, rather than hypothetical, treatment plans for children with HL. These findings provide useful information when counseling families regarding the risks of contemporary RT.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2017

Evaluation of a Machine-Learning Algorithm for Treatment Planning in Prostate Low-Dose-Rate Brachytherapy

Purpose: This work presents the application of a machine learning (ML) algorithm to automatically generate high-quality, prostate low-dose-rate (LDR) brachytherapy treatment plans. The ML algorithm can mimic characteristics of preoperative treatment plans deemed clinically acceptable by brachytherapists. The planning efficiency, dosimetry, and quality (as assessed by experts) of preoperative plans generated with an ML planning approach was retrospectively evaluated in this study. Methods and Materials: Preimplantation and postimplantation treatment plans were extracted from 100 high-quality LDR treatments and stored within a training database. The ML training algorithm matches similar features from a new LDR case to those within the training database to rapidly obtain an initial seed distribution; plans were then further fine-tuned using stochastic optimization. Preimplantation treatment plans generated by the ML algorithm were compared with brachytherapist (BT) treatment plans in terms of planning time (Wilcoxon rank sum, α = 0.05) and dosimetry (1-way analysis of variance, α = 0.05). Qualitative preimplantation plan quality was evaluated by expert LDR radiation oncologists using a Likert scale questionnaire. Results: The average planning time for the ML approach was 0.84 ± 0.57 minutes, compared with 17.88 ± 8.76 minutes for the expert planner (P=.020). Preimplantation plans were dosimetrically equivalent to the BT plans; the average prostate V150% was 4% lower for ML plans (P=.002), although the difference was not clinically significant. Respondents ranked the ML-generated plans as equivalent to expert BT treatment plans in terms of target coverage, normal tissue avoidance, implant confidence, and the need for plan modifications. Respondents had difficulty differentiating between plans generated by a human or those generated by the ML algorithm. Conclusions: Prostate LDR preimplantation treatment plans that have equivalent quality to plans created by brachytherapists can be rapidly generated using ML. The adoption of ML in the brachytherapy workflow is expected to improve LDR treatment plan uniformity while reducing planning time and resources.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2025

Investigating the FLASH Effect in a Rat Brain Organotypic Model With a Novel High-Energy Electron Beam

Ultrahigh dose rate (FLASH) radiation therapy is reported to reduce normal tissue toxicity while maintaining tumor control; however, mechanism(s) remain obscure. To study FLASH mechanisms in brain tissue, we developed a novel experimental platform featuring a specialized high-energy electron linear accelerator, High Intensity Gamma Ray Source (HIGS), paired with an organotypic ex vivo brain metastasis model. We varied interpulse spacing to modulate the mean dose rate (MDR) of our unique 35 MeV electron beam, while maintaining extremely high instantaneous dose rate (IDR). We characterized dosimetry and targeting accuracy of the FLASH beam with film dosimetry. We combined this FLASH beam with an organotypic rat brain slice/breast carcinoma coculture model of brain metastasis to assess effects on normal and neoplastic tissues. Live-cell and bioluminescence imaging demonstrated cancer cell growth effects, whereas normal tissue responses and immune activation were assessed using live-cell imaging, cytokine profiles, and confocal microscopy. Here, we performed comparison experiments with 20 MeV electrons from a Varian clinical linear accelerator (VCLA) using conventional dose rates. The highest IDR of the FLASH beam to date was 20.7 ± 0.6 MGy/s, with maximum MDR of 20.7 MGy/s delivered in 1 pulse of 1 µs duration. Beam targeting was accurate to <1 mm and reproducible. HIGS-FLASH and VCLA dose rates equivalently decreased cancer cell growth. HIGS-FLASH irradiation significantly increased tumor necrosis factor α and fractalkine levels and confocal microscopy revealed distinct changes in microglial morphology slices suggesting microglia activation. Our novel experimental platform produces extremely high dose rates and rapid normal/neoplastic tissue readouts for mechanistic research into the effects of FLASH radiation in the brain. HIGS-FLASH irradiation induces comparable cancer cell growth inhibition but differential effects on cytokines and microglial morphology, suggesting that acute innate immune responses may be involved in FLASH normal tissue effects in the brain.

Kay, Tyler V. [Duke University, Durham, NC (United↗
DOE OSTI2022

Influence of alveolar mixing and multiple breaths of aerosol intake on particle deposition in the human lungs

Predictive dosimetry models play an important role in assessing health effect of inhaled particulate matter and in optimizing delivery of inhaled pharmaceutical aerosols. Here, in this study, the commonly used 1D Multiple-Path Particle Dosimetry model (MPPD) was improved by including a mechanistically based model component for alveolar mixing of particles and by extending the model capabilities to account for multiple breaths of aerosol intake. These modifications increased the retained fraction of particles and consequently particle deposition predictions in the deep lung during tidal breathing. Comparison with an existing dataset (J. Aerosol Sci., 99:27-39, 2016) obtained under two breathing conditions referred to as slow and fast breathing showed significant differences in 1 µm particle deposition between predictions (slow: 30±1%, fast: 21±1%) and measurements (slow: 43±9%, fast: 30±5%) when the prior version of MPPD (single breath and no mixing, J. Aerosol Sci., 151:105647, 2021) was used. Adding a mixing model and multiple breaths moved the predictions (slow: 34±2%, fast:25±2%) closer to the range of deposition measurements. For 2.9 µm particles, predictions from both the original (slow: 70±2%, fast: 57±2%) and the revised MPPD model (slow: 71±2%, fast: 59±3%) compared well with experiments (slow: 67±8%, fast: 58±10%). This was expected as suspended fraction of 2.9 µm particles was small and thus the addition of alveolar mixing and multi breath capability only slightly increased the retained fraction for particles of this size and greater. The revised 1D model improves dose predictions in the deep lung and support human risk assessment from exposure to airborne particles.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2025

Modeling aerosol bolus inhalations in the human lung with the multiple path particle deposition model: Comparison with experimental data

Existing one-dimensional (1D) models of aerosol dosimetry often ignore mixing mechanisms of inhaled aerosols during their transport in the lung. This mixing or aerosol dispersion results from different physical mechanisms in different regions of the lung. It is a higher order effect, which cannot be directly captured in 1D modeling approaches, and thus is sometimes modeled as a diffusive process. Here, in this study, we improved our recently developed alveolar mixing module incorporated in the multiple path particle dosimetry model (MPPD) to account for flow irreversibility and particle trapping in the alveolar spaces, as well as mixing occurring in the tracheobronchial region. This new version of MPPD was coupled with CFPD-based predictions of aerosol bolus dispersion in the oral airway. The model was used to predict the deposition, dispersion, and mode shift of aerosol bolus inhaled at different penetration depths within the lung for breathing patterns and particle size matching those used in a previous experimental study (Darquenne et al., 2016). Even though a quite simplified approach was used, the computations appear to describe subject-specific and test-specific experimental data reasonably well. The proposed combined dispersion-deposition model can be a useful tool for targeted drug delivery and also for exposure health risk assessment.

MPPD↗
DOE OSTI2013

Structural characterization, thermoluminescence and EPR studies of Nd{sub 2}O{sub 3}:Co{sup 2+} nanophosphors

Graphical abstract: Display Omitted Highlights: ► Nd{sub 2}O{sub 3}:Co{sup 2+} (1–4 mol%) nanophosphors have been prepared at much lower temperatures. ► Phosphors are well characterized by PXRD, SEM, TEM, FTIR, Raman, UV–vis spectroscopy. ► EPR and thermoluminescence properties were also reported. ► TL intensity increases linearly with γ dose suggesting usage in radiation dosimetry. -- Abstract: Nd{sub 2}O{sub 3}:Co{sup 2+} (1–4 mol%) nanophosphors (15–25 nm) have been prepared via low temperature solution combustion method. Scanning electron micrograph (SEM) shows that the product is highly porous in nature. The stokes line in the Raman spectrum at ∼2000 cm{sup −1} is assigned to F{sub g} mode and the anti-stokes lines are assigned to a combination of A{sub g} + E{sub g} modes. With increase of Co{sup 2+} concentration, the intensity of F{sub g} mode decreases, whereas the combination of A{sub g} + F{sub g} modes completely disappears. Electron paramagnetic resonance (EPR) spectrum exhibits two resonance signals with effective g values at g = 2.25 and g = 2.03. Thermoluminescence (TL) response of Nd{sub 2}O{sub 3}:Co{sup 2+} nanopowders with γ dose 0.23–2.05 kGy was studied. The activation energy (E) and frequency factor (s) are estimated using Chen's glow peak shape method and obtained to be in the range 0.45–1.67 eV and 1.8 × 10{sup 4} to 4.0 × 10{sup 12} s{sup −1}, respectively. It is observed that the TL glow peak intensity at 430 K increases linearly with γ dose which is suitable for radiation dosimetry.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Evaluation of Neutron Reactions on Iron Isotopes for CIELO and ENDF/B-VIII.0

A new suite of evaluations for {sup 54,56,57,58}Fe has been developed in the framework of the CIELO international collaboration. New resolved resonance ranges were evaluated for {sup 54}Fe and {sup 57}Fe, while modifications were applied to resonances in {sup 56}Fe. The low energy part of the {sup 56}Fe file is almost totally based on measurements. At higher energies in {sup 56}Fe and in the whole fast neutron range for minor isotopes the evaluation consists of model predictions carefully adjusted to available experimental data. We also make use of the high quality and well experimentally-constrained dosimetry evaluations from the IRDFF library. Special attention was dedicated to the elastic angular distributions, which were found to affect results of the integral benchmarking. The new set of iron evaluations was developed in concert with other CIELO evaluations and they were tested together in the integral experiments before being adopted for the ENDF/B-VIII.0 library.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗