Distribution Of Radioactivity Research Articles

2 Year Quality of Life Follow up Following Palladium-103 Line Source for Prostate Brachytherapy Implants

To assess the quality of life (QOL) following the implant of a polymer encapsulated Pd-103 source with a unique linear radioactive distribution intended to provide a useful refinement on prostate brachytherapy. Prostate brachytherapy is known to successfully treat prostate cancer with minimal side effects to patients. Urinary, rectal and sexual function toxicities are reported with standard questionnaires to assess QOL in this registry study. Thirty-seven subjects with prostate cancer were implanted with the Pd-103 line source. Prostate specific antigen (PSA) was recorded before implant and in 6 month intervals following implant. Patients were asked to respond to International Prostate Symptom Score (IPSS), Rectal Function Assessment Score (RFAS), and International Index of Erectile Function (IIEF) questionnaires. Questionnaires were administered before implant, one month after implant, and at 6 month intervals following implant. PSA and responses to questionnaires have been collected for up to 24 months for some patients. Patients were not excluded based on pre-implant QOL function. The average PSA prior to implant and at 6 months following implant were 7.7 and 1.2, respectively. A total of 37 patients responded to the questionnaires prior to linear Pd-103 implant. Very mild urinary symptoms were reported following implant, including mild increase in frequency and urgency. These symptoms resolved prior to 6 month follow up. The average baseline IPSS for all patients is 9.1. The average post implant IPSS change from baseline was 11.3, 3, 1.9, 3.1 and 0.3 for months 1, 6, 12, 18 and 24, respectively. The IPSS reported for Pd-103 linear sources indicate that return to baseline may occur more rapidly than with traditional seeds. No adverse events related to rectal toxicity were reported. The average change from baseline RFAS and IIEF were 2 and 5, respectively, at one month post implant and returned to baseline by 6 months. No statistically significant changes from baseline in the RFAS or IIEF over the 2 year follow up period. Patients tolerate Pd-103 line source brachytherapy with minimal side effects. Immediate symptoms from the procedure resolve quickly and patients routinely return to baseline function.

Inverse estimation methods of unknown radioactive source for fuel debris search

To identify the distribution of fuel debris remaining in the reactor vessel and/or the containment vessel of Fukushima Daiichi NPS, we focused on the inverse estimation of radioactive source distribution using the measured radiation counts. The Maximum Likelihood-Expectation Maximization (ML-EM) and the Moore-Penrose Matrix Inverse (MPMI) methods are examined. The ML-EM method has been used for the image reconstruction of computed tomography, and the MPMI method is one of the solution methods for simultaneous linear equations with the underdetermined condition. A simple calculation model simulating a containment vessel was constructed including detectors and radiation sources. In an actual situation, a sufficient number of radiation measurement positions would not be available owing to the complexity of structures inside the containment vessel. Thus, the number of radiation measurement points (number of constraints) is smaller than that of radiation source positions. It means that an underdetermined inverse problem should be solved. The detection probability of radiation (neutron or photon) is calculated by the adjoint transport calculation since the detection probability is used as the coupling coefficient between radiation counts at a detector and a radioactive source. The result of estimation using the ML-EM or the MPMI method indicates that the accuracy of estimation depends on the distance between a radiation source and a detector, and measurement positions of radiation count. The ML-EM and the MPMI methods show different prediction accuracy depending on the prediction condition. It is found that reasonable prediction accuracy would be obtained when the detectors are placed at the vicinity of radiation sources of interest.

Utilization of Chemical Deposition Technique for Preparation of Miniature 170Tm Sources and Preliminary Quality Assessment for Potential Use in Brachytherapy

This article describes the preparation of a 170Tm source by chemical deposition technique, its encapsulation in a titanium holder, and preliminary quality evaluation for potential utility as a brachytherapy source. The procedure consisted of electrodeposition of Ni on a Cu wire followed by chemical deposition of 170Tm on it. Influence of feed solution pH, carrier Tm concentration, and reaction time were studied for optimum deposition of 170Tm on substrate. After sealing the source core in a titanium capsule, quality control tests were performed. Distribution of 170Tm on substrate was evaluated by autoradiography. Inactive Tm source was characterized by scanning electron microscope (SEM) and energy-dispersive X-ray (EDS) analyses. Under optimized conditions (pH 5, 10 μg Tm carrier, 5 h), 170Tm source core could be prepared by deposition of >95% of 170Tm radioactivity on substrate. Swipe tests and immersion tests on encapsulated sources confirmed that removable radioactivity and radioactivity leakage levels were within stipulated limits. Autoradiography of 170Tm source confirmed uniformity of radioactivity distribution. While SEM analysis confirmed good adhesion of Tm on substrate, EDS analysis confirmed elemental constituents of the Tm-deposited substrate. The objective of preparing a 170Tm source by chemical deposition for potential brachytherapy applications could be successfully achieved.

Simulation study of the effects of buildings, trees and paved surfaces on ambient dose equivalent rates outdoors at three suburban sites near Fukushima Dai-ichi

The influence of buildings, trees and paved surfaces on outdoor ambient dose equivalent rates (H˙∗(10)) in suburban areas near to the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) was investigated with Monte Carlo simulations. Simulation models of three un-decontaminated sites in Okuma and Tomioka were created with representations of individual buildings, trees and roads created using geographic information system (GIS) data. The 134Cs and 137Cs radioactivity distribution within each model was set using in-situ gamma spectroscopy measurements from December 2014 and literature values for the relative radioactive cesium concentration on paved surfaces, unpaved land, building outer surfaces, forest litter and soil layers, and different tree compartments. Reasonable correlation was obtained between the simulations and measurements for H˙∗(10) across the sites taken in January 2015. The effect of buildings and trees on H˙∗(10) was investigated by performing simulations removing these objects, and their associated 134Cs and 137Cs inventory, from the models. H˙∗(10) were on average 5.0% higher in the simulations without buildings and trees, even though the total 134Cs and 137Cs inventory within each model was slightly lower. The simulations without buildings and trees were then modified to include 134Cs and 137Cs in the ground beneath locations where buildings exist in reality, and the inventory of paved surfaces modelled as if they had high retention of 134Cs and 137Cs fallout like soil areas. H˙∗(10) increased more markedly in these cases than when considering the shielding effect of buildings and trees alone. These results help clarify the magnitude of the effect of buildings, trees and paved surfaces on H˙∗(10) at the un-decontaminated sites within Fukushima Prefecture.

Mapping radiation distribution on ground based on the measurement using an unmanned aerial vehicle

Mapping the radiation distribution on ground during a radiological emergency monitoring, or decontamination mission is an important task. Accurate knowledge of the radioactivity distribution can help radiation workers locate the contamination, which reduces unnecessary radiation exposure to personnel and perhaps to some extent also the exposure to the public. Recently, radiation monitoring systems based on unmanned aerial vehicles (UAV) have been widely studied and employed. However, development of algorithms for mapping the contamination from measured data obtained by the detection system mounted on an UAV is still lacking. In this work, we implemented an advanced statistical reconstruction algorithm for mapping spread and point radiation contamination. The algorithm significantly improves accuracy in the scope and location of radiation contamination.

Biological characteristics of 18F-FDG PET/CT imaging of cerebral alveolar echinococcosis.

This study aims to analyze the characteristics of 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) for cerebral alveolar echinococcosis (CAE).Twenty-five CAE patients underwent 18F-FDG PET/CT, and the diagnosis was confirmed by clinical and surgical pathology. The 18F-FDG PET/CT results were subject to visual and semiquantitative analysis, and the difference in 18F-FDG SUVmax for lesions among the 3 types of CAE was evaluated.In the 25 CAE patients, 62 lesions were detected by 18F-FDG PET/CT, and these lesions were classified into 3 types, according to the characteristics of the lesion's uptake of 18F-FDG on PET images: type I, 17 lesions, FDG was concentrated into a mass radioactive distribution in the CAE foci; type II, 28 lesions, FDG presented a annular concentrated radioactive distribution around the CAE foci; type III, 17 lesions, FDG in the CAE foci presented a radioactive distribution with defects and sparse areas. The difference in 18F-FDG SUVmax between type I and type II CAE was not statistically significant (P > .05), the difference in 18F-FDG SUVmax between type I and type III CAE was statistically significant (P < .001), and the difference in 18F-FDG SUVmax between type II and type III CAE was statistically significant (P < .001);The 18F-FDG PET manifestations of CAE are classified into 3 types. Both type I and type II may have invasive activity, while the lesions of type III CAE show that the focus is relatively stable or at a stationary phase. If there are no definite alveolar echinococcus focus in other sites, these patients can temporarily delay the treatment. It is recommended that the patient should undergo whole body PET/CT once a year to dynamically observe the bioactivity and size of type III CAE lesions and assess the presence of new echinococcus lesions in the rest of the body.

Near-Infrared-Triggered in Situ Gelation System for Repeatedly Enhanced Photothermal Brachytherapy with a Single Dose.

Brachytherapy by the placing of therapeutic radioactive materials into or near tumors has been widely used in a clinical setting for cancer treatment. The efficacy of brachytherapy, however, may often be limited by the radiation resistance for tumor cells located in the hypoxic region of a solid tumor as well as the non-optimal distribution of radioactivity inside the tumor. Herein, a hybrid hydrogel system is developed by using 131I-labeled copper sulfide (CuS/131I) nanoparticles as the photothermal- and radiotherapeutic agent, poly(ethylene glycol) double acrylates (PEGDA) as the polymeric matrix, and 2,2'-azobis[2-(2-imidazolin-2-yl) propane] dihydrochloride (AIPH) as the thermal initiator to realize light-induced in situ gelation in the tumor for the combined photothermal brachytherapy. After local injection, CuS/131I nanoparticles under irradiation by the 915 nm near-infrared (NIR) laser would produce heat to mildly raise the tumor temperature and initiate the polymerization of PEGDA by activating the AIPH thermal initiator, effectively fixing CuS/131I by in situ gelation within the tumor for the long term. By the repeated NIR irradiation of tumors, the tumor hypoxia could be relieved for a much-longer term, resulting in a significant synergistic photothermal brachytherapeutic effect to eliminate tumors. This work presents an efficient type of NIR-responsive nanoparticle-encapsulated hydrogel system, inspiring the design of a form of brachytherapy.

Radioactivity Distributions in Soils from Three Central Districts of Bangladesh and their Radiological Consequences

Radioactivity Distributions in Soils from Three Central Districts of Bangladesh and their Radiological Consequences

Spatial relationship between the field-measured ambient gamma dose equivalent rate and geological conditions in a granitic area, Velence Hills, Hungary: An application of digital spatial analysis methods

In order to estimate the annual dose that the public receive from natural radioactivity, the identification of the potential risk areas is required which, in turn, necessitates understanding the relationship between the spatial distribution of natural radioactivity and the geogenic risk factors (e.g., rock types, presence of dikes, faults, physical conditions of soil, etc.). A detailed spatial analysis of outdoor ambient gamma dose equivalent rate was performed in the western side of Velence Hills, the largest outcropped granitic area in Hungary. In order to assess the role of local geology in the spatial distribution of gamma dose rates, field measurements were carried out at ground level at 300 sites along a 250 m x 250 m regular grid in a total surface of 19.8 km2. Digital image processing methods were applied to identify anomalies, heterogeneities and spatial patterns in the measured gamma dose rates, including local maxima and minima determination, digital cross sections, gradient magnitude and gradient direction, second derivative profile curvature, local variability, lineament density, 2D autocorrelation and directional variogram analyses. Statistical inference shows that different gamma dose rate levels are associated with the geological formations, with the highest level on the Carboniferous granite including outlying values. Moreover, digital image processing reveales that linear gamma dose rate spatial features are parallel to the SW-NE dike system and to the NW-SE main fractures. The results of this study underline the importance of understanding the role of geogenic risk factors influencing the ambient gamma dose equivalent rate received by public. The study also demonstrates the power of the image processing techniques for the identification of spatial pattern in field-measured geogenic radiation.

Targeting Micrometastases: The Effect of Heterogeneous Radionuclide Distribution on Tumor Control Probability.

The spatial distribution of radiopharmaceuticals that emit short-range high linear-energy-transfer electrons greatly affects absorbed dose and biological effectiveness. The purpose of this study was to investigate the effect of heterogeneous radionuclide distribution on tumor control probability (TCP) in a micrometastasis model. Methods: The cancer cell lines MDA-MB-468, SQ20B, and 231-H2N were grown as spheroids to represent micrometastases. The intracellular distribution of a representative radiopeptide (111In-labeled epidermal growth factor) and radioimmunotherapeutic (111In-labeled trastuzumab) was determined in cell internalization experiments. The intratumoral distribution was evaluated by microautoradiography of spheroids. γH2AX staining was performed on spheroid sections to correlate DNA damage with radionuclide distribution. Experimental surviving fractions were obtained using clonogenic assays. A random close-packed algorithm, which models the random packing behavior of cells and reflects variation in the radii of cells and nuclei, was used to simulate 3-dimensional spheroids. Calculated survival fractions were generated using an iterative modeling method based on Monte Carlo–determined absorbed dose with the PENELOPE code and were compared with experimental surviving fraction. Radiobiologic parameters deduced from experimental results and Monte Carlo simulations were used to predict the TCP for a 3-dimensional spheroid model. Results: Calculated survival fractions agreed well with experimental data, particularly when an increased value for relative biological effectiveness was applied to self-dose deposited by sources located in the nucleus and when radiobiologic parameters were adjusted to account for dose protraction. Only in MDA-MB-468 spheroids treated with 111In-epidermal growth factor was a TCP of more than 0.5 achieved, indicating that for this cell type the radiopeptide would be curative when targeting micrometastases. This ability is attributed to the relative radiosensitivity of MDA-MB-468 cells, high nuclear uptake of the radiopeptide, and uniform distribution of radioactivity throughout the spheroid. Conclusion: It is imperative to include biologic endpoints when evaluating the distribution of radionuclides in models emulating micrometastatic disease. The spatial distribution of radioactivity is a clear determinant of biological effect and TCP as demonstrated in this study.

International Prostate Symptom Score Assessment following Palladium-103 Line Source for Prostate Brachytherapy Implants

To assess the International Prostate Symptom Score (IPSS) following the implant of a polymer encapsulated Pd-103 source with a unique linear radioactive distribution intended to provide a useful refinement on prostate brachytherapy. A registry study collects patient reported outcomes following brachytherapy, including the IPSS questionnaire.

Uniform intratumoral distribution of radioactivity produced using two different radioagents, 64Cu-cyclam-RAFT-c(-RGDfK-)4 and 64Cu-ATSM, improves therapeutic efficacy in a small animal tumor model

BackgroundThe present study proposed a new concept for targeted radionuclide therapy (TRT) to improve the intratumoral distribution of radioactivity using two different radiopharmaceuticals. We examined the efficacy of a combination of a tetrameric cyclic Arg-Gly-Asp (cRGD) peptide-based radiopharmaceutical, 64Cu-cyclam-RAFT-c(-RGDfK-)4 (64Cu-RaftRGD, an αVβ3 integrin [αVβ3] tracer), and 64Cu-diacetyl-bis (N4-methylthiosemicarbazone) (64Cu-ATSM, a supposed tracer for hypoxic metabolism) in a small animal tumor model.ResultsMice with subcutaneous αVβ3-positive U87MG glioblastoma xenografts were used. The intratumoral distribution of a near-infrared dye, Cy5.5-labeled RAFT-c(-RGDfK-)4 (Cy5.5-RaftRGD), 64Cu-RaftRGD, and 64Cu-ATSM was visualized by fluorescence imaging and autoradiography of the co-injected Cy5.5-RaftRGD with 64Cu-RaftRGD or 64Cu-ATSM at 3 h postinjection. Mice were treated with a single intravenous dose of the vehicle solution (control), 18.5 or 37 MBq of 64Cu-RaftRGD or 64Cu-ATSM, or a combination (18.5 MBq of each agent). The tumor volume, tumor cell proliferation, body weight, survival, and tumor and organ uptake of radiopharmaceuticals were assessed. It was shown that Cy5.5-RaftRGD colocalized with 64Cu-RaftRGD and could be used as a surrogate for the radioactive agent. The intratumoral distribution of Cy5.5-RaftRGD and 64Cu-ATSM was discordant and nearly complementary, indicating a more uniform distribution of radioactivity achievable with the combined use of 64Cu-RaftRGD and 64Cu-ATSM. Neither 64Cu-RaftRGD nor 64Cu-ATSM showed significant effects on tumor growth at 18.5 MBq. The combination of both (18.5 MBq each) showed sustained inhibitory effects against tumor growth and tumor cell proliferation and prolonged the survival of the mice, compared to that by either single agent at 37 MBq. Interestingly, the uptake of the combination by the tumor was higher than that of 64Cu-RaftRGD alone, but lower than that of 64Cu-ATSM alone. The kidneys showed the highest uptake of 64Cu-RaftRGD, whereas the liver exhibited the highest uptake of 64Cu-ATSM. No obvious adverse effects were observed in all treated mice.ConclusionsThe combination of 64Cu-RaftRGD and 64Cu-ATSM achieved an improved antitumor effect owing to the more uniform intratumoral distribution of radioactivity. Thus, combining different radiopharmaceuticals to improve the intratumoral distribution would be a promising concept for more effective and safer TRT.

Assessment of Radioactivity in Various Types of Soil From Al-Obour City, Egypt.

The distributions of natural radioactivity in various types of samples collected from several areas in Al-Obour city were determined using a high purity germanium (HPGe) detector. Four types of samples were investigated: soil, foundations, sand dunes and rock samples. The specific activities of 238U, 226Ra series, 232Th and 40K in soil; foundations; sand dunes and rock samples have a mean of (13.31±3.59); (12.96±3.63); (13.36±4.32) and (26.74±5.50), (6.49±0.23); (3.71±0.16); (3.87±0.17) and (19.38±0.64), (6.52±0.55); (4.03±0.46); (3.90±0.45) and (25.91±1.89) and (96.21±1.60); (78.12±1.46); (76.27±1.43) and (215.71±3.35)Bq/kg, respectively.It was also noticed that 137Cs is existed in some samples but is close to the background level. The hazard indices were also determined in all types of samples of the under study area. These values are important to establish baseline levels of this environmental radioactivity to detect any upcoming change for the local population.

Novel Method of Quantifying Radioactive Cesium-Rich Microparticles (CsMPs) in the Environment from the Fukushima Daiichi Nuclear Power Plant.

Highly radioactive cesium-rich microparticles (CsMPs) were released from the Fukushima Daiichi nuclear power plant (FDNPP) to the surrounding environment at an early stage of the nuclear disaster in March of 2011; however, the quantity of released CsMPs remains undetermined. Here, we report a novel method to quantify the number of CsMPs in surface soils at or around Fukushima and the fraction of radioactivity they contribute, which we call "quantification of CsMPs" (QCP) and is based on autoradiography. Here, photostimulated luminescence (PSL) is linearly correlated to the radioactivity of various microparticles, with a regression coefficient of 0.0523 becquerel/PSL/h (Bq/PSL/h). In soil collected from Nagadoro, Fukushima, Japan, CsMPs were detected in soil sieved with a 114 μm mesh. There was no overlap between the radioactivities of CsMPs and clay particles adsorbing Cs. Based on the distribution of radioactivity of CsMPs, the threshold radioactivity of CsMPs in the size fraction of <114 μm was determined to be 0.06 Bq. Based on this method, the number and radioactivity fraction of CsMPs in four surface soils collected from the vicinity of the FDNPP were determined to be 48-318 particles per gram and 8.53-31.8%, respectively. The QCP method is applicable to soils with a total radioactivity as high as ∼106 Bq/kg. This novel method is critically important and can be used to quantitatively understand the distribution and migration of the highly radioactive CsMPs in near-surface environments surrounding Fukushima.

First demonstration of in vivo mapping for regional brain monoacylglycerol lipase using PET with [11C]SAR127303

Monoacylglycerol lipase (MAGL) is a main regulator of the endocannabinoid system within the central nervous system (CNS). Recently, [11C]SAR127303 was developed as a promising radioligand for MAGL imaging. In this study, we aimed to quantify regional MAGL concentrations in the rat brain using positron emission tomography (PET) with [11C]SAR127303. An irreversible two-tissue compartment model (2-TCMi, k4 = 0) analysis was conducted to estimate quantitative parameters (k3, Ki2-TCMi, and λk3). These parameters were successfully obtained with high identifiability (<10 %COV) for the following regions ranked in order from highest to lowest: cingulate cortex > striatum > hippocampus > thalamus > cerebellum > hypothalamus ≈ pons. In vitro autoradiographs using [11C]SAR127303 showed a heterogeneous distribution of radioactivity, as seen in the PET images. The Ki2-TCMi and λk3 values correlated relatively highly with in vitro binding (r > 0.4, P < 0.005). The Ki2-TCMi values showed high correlation and low underestimation (<10%) compared with the slope of a Patlak plot analysis with linear regression (KiPatlak). In conclusion, we successfully estimated regional net uptake value of [11C]SAR127303 reflecting MAGL concentrations in rat brain regions for the first time.

DOSE ASSESSMENT FOR TYPICAL NPP-2006 STAFF FOR DESIGN BASIS ACCIDENT TAKING INTO ACCOUNT SITE INFRASTRUCTURE

Assessment of radiation effect on nuclear power plant staff was made for design basis accident. The considered accident scenario includes spent fuel assembly drop into the reactor core or fuel pool during load-unload operations with fuel assemblies damage and radionuclide emission. The proposed method included the assessment of radionuclide sedimentation on characteristic surfaces of nuclear power plant site, calculations of radioactive aerosol distribution depending on the distance of emission source in COMSOL 3.5 program. The software module is based on highly detailed account of the infrastructure of the nuclear power plant industrial site according to the master plan, which allows obtaining more accurate estimation of radioactive substances deposition and, as a result, more accurate calculation of doses for staff and population. The assessment of average volume activity in lower air layer on site during VVER design basis accident is performed. Doses from radioactive cloud (external exposure) and from inhalation (internal exposure) were estimated for following radionuclides: 137 Cs, 131 I, 133 I, 90 Sr. In the case of the design basis accident associated with the fall of the assembly during fuel load-unload operations the received value of the total effective dose of staff exposure is 7.80 mSv for the first 8 hours after the accident beginning. This number is well below the threshold of the allowable annual dose limit for personnel in emergency situations (50 mSv).

Radioactive Element Distribution Characteristics of Red Mud based Field Road Cement before and after Hydration

Red mud was firstly used as a raw material in sintering field road cement. Then, the radioactive element distribution characteristics of red mud based field road cement (RFC) before and after hydration were comparatively investigated. The experimental results indicated that the specific activity of 226Ra and 232Th increased after sintering process from raw material to clinker, as a result of concentrating effect on 226Ra and 232Th during sintering process, but the specific activity of 40K decreased after sintering process as a result of volatilization effect. Radionuclide 226Ra mainly distributed in RFC silicate phases (C x S), 232Th distributed more in RFC interstitial phases than RFC silicate phases (C x S), 40K mainly distributed in RFC interstitial phases. With increasing hydration ages of RFC pastes, the specific activity of 226Ra kept increasing, 232Th remained consistency all the same and 40K declined. The radioactivity of RFC was in the recommended safe limit of Chinese National Standards GB6566-2010 during its preparation and application process.

Assessment of radioactivity of environmental components in the Kostomuksha State Nature Reserve

The radiological state of the land and water areas constantly attracts public interest. Specially protected natural reservations deserve special attention when it comes to studying radiological conditions. This study presents findings of radioecological investigations conducted in the Kostomuksha State Nature Reserve in 2012 – 2015. The Kostomuksha Mining Company, which is developing the Kostomuksha iron ore deposit was identified as a potentially hazardous facility that might affect the radioecological situation in the naturel reserve, since production of iron ores at the deposit involves extraction to the ground surface of acid rocks characterised by a naturally high content of radioactive elements (granitic gneiss). Furthermore, several sources of radioactive radon gas have been identified within the reserve boundaries. The study included investigation of natural and anthropogenic radioactivity in the environmental components of the nature reserve and adjacent territories, including soil, plants, bottom sediments, ambient air and natural waters. It was found that development of the Kostomuksha iron ore deposit and operations of the mining and processing plant do not exert any considerable impact on the radiological situation in the nature reserve. Data obtained during the study indicate that the overall radiological situation in the reserve is acceptable and meets the relevant radiation safety standards. High levels of radiocesium were found in the moss and bottom sediments of the nature reserve, which requires additional research to determine a wider pattern of distribution of anthropogenic radioactivity across the adjacent territories and to study the processes of buildup and migration of radionuclides in aquatic organisms of Kamennoye Lake.

Application of modern autoradiography to nuclear forensic analysis

Modern autoradiography techniques based on phosphorimaging technology using image plates (IPs) and digital scanning can identify heterogeneities in activity distributions and reveal material properties, serving to inform subsequent analyses. Here, we have adopted these advantages for applications in nuclear forensics, the technical analysis of radioactive or nuclear materials found outside of legal control to provide data related to provenance, production history, and trafficking route for the materials. IP autoradiography is a relatively simple, non-destructive method for sample characterization that records an image reflecting the relative intensity of alpha and beta emissions from a two-dimensional surface. Such data are complementary to information gathered from radiochemical characterization via bulk counting techniques, and can guide the application of other spatially resolved techniques such as scanning electron microscopy (SEM) and secondary ion mass spectrometry (SIMS). IP autoradiography can image large 2-dimenstional areas (up to 20×40cm), with relatively low detection limits for actinides and other radioactive nuclides, and sensitivity to a wide dynamic range (105) of activity density in a single image. Distributions of radioactivity in nuclear materials can be generated with a spatial resolution of approximately 50μm using IP autoradiography and digital scanning. While the finest grain silver halide films still provide the best possible resolution (down to ∼10μm), IP autoradiography has distinct practical advantages such as shorter exposure times, no chemical post-processing, reusability, rapid plate scanning, and automated image digitization. Sample preparation requirements are minimal, and the analytical method does not consume or alter the sample. These advantages make IP autoradiography ideal for routine screening of nuclear materials, and for the identification of areas of interest for subsequent micro-characterization methods. In this paper we present a summary of our setup, as modified for nuclear forensic sample analysis and related research, and provide examples of data from select samples from the nuclear fuel cycle and historical nuclear test debris.

Verification of Activity Accumulation Location Effect in Patients Treated with I-131 Radio Pharmacy on the Evaluated Exposure at Different Distances from Patient using NCAT Phantom

Introduction: One of the most common applications of medical isotopes is in treatment of cancer and hyperthyroidism using Iodine-131. The Iodine-131 cumulates in cancerous cells and acts as a source of radioactive emissions. Apparently, local and temporal distributions of the radioactive material are different in various organs. In this paper, the effect of radioactive Iodine distribution on the amount of exposure at different distances has been investigated. Materials & Methods: This analysis has been carried out using adult NCAT phantoms, Monte-Carlo simulation, and GATE code. By applying the same amount of activity on five different organs of the phantom, the quality and quantity of energy has been computed as well as the amount of emitted exposures at distances of one, two, and three meters. Then, by setting thyroid as the basis, the difference of exposure emitted from other four organs has been calculated and analyzed using KS test. Findings: Simulation results had been showed that the amounts of exposure that emitted from aforementioned organs are significantly different at the distance of one meter whereas this difference diminishes significantly at distances of two and three meters. In other words, the effect of radioactive Iodine integration location on the emitted exposure is being trivial as the distance increases. Discussion & Conclusions: Distinct TEDE values must be defined for each of the aforementioned organs and confirmed before releasing patients who will be faced to the others at short distances. Otherwise, guidelines must be considered for the others who will be faced to the released patient.