Fast Neutron Measurement System Using Prompt Gamma Neutron Activation Solid Converter: Monte Carlo Study.

Measuring fast neutron emission around accelerators is important for purposes of environmental monitoring and radiation safety. It is necessary to detect two types of neutrons: thermal and fast. Fast neutron spectroscopy is commonly employed using a hydrogen-recoil proportional-counter; however, its threshold is 2 MeV. The aim of this study was to expand PGNA converters based on KCl to fulfil the need to detect neutron energies ranging from 0.02 MeV to 3 MeV. In our previous research, we established a counting system comprised of a large converter of KCl with a NaI(Tl) gamma radiation spectrometer. The KCl converter is efficient for fast neutron prompt gamma emission. The potassium naturally includes a radioisotope that emits 1.460 MeV gamma rays. The presence of the constant level of 1.460 MeV gamma ray counts offers an advantage, providing a stable background for the detector. The study was carried out using MCNP simulations of the counting system with a variety of PGNA converters based on KCl. We concluded that KCl mixtures combined with other elements, such as PGNA converters, demonstrated improved detection performance for fast neutron emissions. Furthermore, an explication of how to add materials to KCl to provide a proper converter for fast neutrons was introduced.

Neutronics Simulations for DEMO Diagnostics.

One of the main challenges in the development of a plasma diagnostic and control system for DEMO is the need to cope with unprecedented radiation levels in a tokamak during long operation periods. A list of diagnostics required for plasma control has been developed during the pre-conceptual design phase. Different approaches are proposed for the integration of these diagnostics in DEMO: in equatorial and upper ports, in the divertor cassette, on the inner and outer surfaces of the vacuum vessel and in diagnostic slim cassettes, a modular approach developed for diagnostics requiring access to the plasma from several poloidal positions. According to each integration approach, diagnostics will be exposed to different radiation levels, with a considerable impact on their design. This paper provides a broad overview of the radiation environment that diagnostics in DEMO are expected to face. Using the water-cooled lithium lead blanket configuration as a reference, neutronics simulations were performed for pre-conceptual designs of in-vessel, ex-vessel and equatorial port diagnostics representative of each integration approach. Flux and nuclear load calculations are provided for several sub-systems, along with estimations of radiation streaming to the ex-vessel for alternative design configurations. The results can be used as a reference by diagnostic designers.

Atmospheric dispersion modeling for an accidental release from a SLOWPOKE-2 research reactor: a case study.

Atmospheric dispersion modeling was performed for a postulated design basis accident at a SLOWPOKE research reactor. The MCNP-5 computer code was used to estimate the neutron flux spectrum which was then used in the ORIGEN-S code to perform core depletion calculations and determine the radiological source term. The HotSpot health physics code was then used to model the atmospheric transport of the radioactive material released to estimate the resulting doses to the population downwind of the reactor. The highest total effective dose (TED) for a release from the reactor's exhaust stack in predominant meteorological conditions, stability class C, was 0.37 mSv, while a maximum TED of 4.29 mSv was estimated for a release at ground level. Ground deposition was estimated to be 3900 kBq/m2. It was shown that any hypothetical release of radioactive material resulting from such an accident would have no significant adverse effect on the municipal water reservoir close to the reactor.

Computational dose evaluation on children exposed to natural radioactivity from granitic rocks used as architectural materials.

Considering the higher radiosensitivity of children in comparison to adults, studies related to children's exposure to ionising radiation have been long considered of relevance. For this study, the MCNPX2.7.0 Monte Carlo code and four paediatric voxel computational anthropomorphic phantoms, of both genders and aged 5 and 10 years, were used to simulate scenarios, where children are exposed to natural radiation emitted by sources in the ground by radionuclides of40K and of232Th and238U radioactive series. These elements are part of the composition of ten different types of ornamental rocks obtained from three regions of Brazil, and used as architectural material for flooring of houses. The virtual paediatric anthropomorphic phantoms were positioned in a room with dimensions of (4.0 × 5.0 × 2.8) m3filled with atmospheric air and a 3 cm thick granitic floor acting as a uniformly distributed planar gamma radiation source. The walls of the room were composed of 20 cm thick concrete. Gonads, bone marrow, bladder, colon, and skin were found to be the organs which receive the highest doses. The mean values of effective dose per air kerma at 1 m above the ground summed for all three radionuclides, were 0.96 and 0.68 Sv Gy-1for the 5 and 10 year old phantoms, respectively. The obtained results showed that the granitic rocks considered implicate annual effective doses which are 69%-78% lower than the annual limits, recommended by ICRP Publication 103.

Skin dose contamination conversion coefficients. Benchmark with three simulation codes.

Handling of radioactive material by operators can lead to contamination at the surface of the skin in case of an accident. The quantification of the dose received by the skin due to a contamination scenario is performed by means of dedicated dose coefficients as it is the case for other radiation protection dose quantities described in the literature. However, most available coefficients do not match realistic scenarios according to state-of-the-art of science and technology. Therefore, this work deals with dedicated dose conversion factors for skin contamination. Since there is an increasing demand on dose coefficients in general, these specific coefficients can be used for various calculations in radiation protection. In this work a method to evaluate such coefficients for the skin contamination dose related to photons, electrons, positrons, alpha and neutron particles is proposed. The coefficients are generated using Monte-Carlo simulations with three well established calculation codes (FLUKA, MCNP, and GEANT4). The results of the various codes are compared against each other for benchmarking purposes. The new dose coefficients allow the computation of the skin received dose, in the case of skin contamination scenario of an individual, taking into account the decay radiation of the radionuclides of interest. To benchmark the quantity derived here, comparisons of radionuclide contamination doses to the skin using the VARSKIN code available in the literature are performed with the results of this work.

Voxel model of a rabbit: assessment of absorbed doses in organs after CT examination performed by two different protocols.

The objective of this work was to assess absorbed doses in organs and tissues of a rabbit, following computed tomography (CT) examinations, using a dedicated 3D voxel model. Absorbed doses in relevant organs were calculated using the MCNP5 Monte Carlo software. Calculations were perfomed for two standard CT protocols, using tube voltages of 110 kVp and 130 kVp. Absorbed doses were calculated in 11 organs and tissues, i.e., skin, bones, brain, muscles, heart, lungs, liver, spleen, kidney, testicles, and fat tissue. The doses ranged from 15.3 to 28.3 mGy, and from 40.2 to 74.3 mGy, in the two investigated protocols. The organs that received the highest dose were bones and kidneys. In contrast, brain and spleen were organs that received the smallest doses. Doses in organs which are stretched along the body did not change significantly with distance. On the other hand, doses in organs which are localized in the body showed maximums and minimums. Using the voxel model, it is possible to calculate the dose distribution in the rabbit's body after CT scans, and study the potential biological effects of CT doses in certain organs. The voxel model presented in this work can be used to calculated doses in all radiation experiments in which rabbits are used as experimental animals.

Virtual Igor: an analytical phantom for the simulation of the Saint Petersburg brick phantom in arbitrary layouts in MCNP.

A computer code called Virtual Igor is presented. The code generates an analytical representation of the Saint Petersburg brick phantom family (Igor, Olga, Irina), which is frequently used for the calibration of whole-body counters, in arbitrary user-defined layouts for the use in the Monte-Carlo radiation transport code MCNP. The computer code reads a file in the ldraw format, which can easily be produced by simple freeware software with graphical user interfaces and which contains the types and coordinates of the bricks. Ldraw files with the canonical layouts of the brick phantom are provided with Virtual Igor. The code determines the positions of (2.75 cm)3 segments of the bricks, where 2.75 cm is the smallest length in the layout and, therefore, represents the spacing of the segment lattice. Each segment contains the exact geometry of the respective part of the brick, using cuboid and cylindrical surfaces. The user can define which rod source drill holes of which bricks contain the rod-type radionuclide sources. The method facilitates the comparison of different layouts of the Saint Petersburg brick phantom with each other and with anthropomorphic computational phantoms.

A comparison of CFPD, compartment, and uniform distribution models for radiation dosimetry of radionuclides in the lung.

Radioactive aerosols that arise from natural sources and nuclear accidents can be a long-term hazard to human health. Despite the heterogeneous particle deposition in the respiratory tract, uniform aerosol doses have long been assumed in respiratory radiation dosimetry predictions, such as in the compartment and uniform distribution models. It is unclear how these deposition patterns affect internal radiation doses, which are critical in the health assessment of radioactive hazards. This work seeks to quantify the radio-dosimetry sensitivity to initial deposition patterns by comparing computational and compartment/uniform models. A new approach was developed to implement the compartment model into voxel phantoms (e.g. VIP-man) for radiation dosimetry. The calculated radiation fluence, energy deposition density and organ doses were compared to those obtained from coupling computational fluid-particle dynamics (CFPD) with Monte Carlo radiation transport and to those obtained from uniform source distribution approximation. The results show that the source particle distribution within the respiratory system substantially influences the radiation dosimetry distribution. The compartment and uniform models underestimated aerosol deposition in the crania ridge, leading to lower doses in the trachea and surrounding organs. For 0.5 MeV gammas, the CFPD-Monte Carlo N-particle (MCNP) model predicted a tracheal dose twice that of the compartment model and four times the uniform model. For 1 MeV betas, the CFPD-MCNP-predicted tracheal dose is 2.6 times that of the compartment model and 14 times the uniform model. Compared to the compartment/uniform models, the CFPD approach predicted a 50% lower beta dose in the lung but higher beta doses in the heart (six times), liver (four times) and stomach (2.5 times). It is suggested that including compartments for the lung periphery and tracheal carina ridge may improve the dosimetry accuracy of compartment models.

Calculation and benchmark of fluence-to-local skin equivalent dose coefficients for neutrons with FLUKA, MCNP, and GEANT4 Monte-Carlo codes.

Dose equivalent limits for single organs are recommended by the ICRP (International Commission for the Radiological Protection publication 103). These limits do not lend themselves to be measured. They are assessed by convoluting conversion factors with particle fluences. The Fluence-to-Dose conversion factors are tabulated in the ICRP literature. They allow assessing the organ dose of interest using numerical simulations. In particular, the literature lacks the knowledge of local skin equivalent dose (LSD) coefficients for neutrons. In this article, we compute such values for neutron energies ranging from 1 meV to 15 MeV. We use FLUKA, MCNP and GEANT4 Radiation transport Monte-Carlo simulation codes to perform the calculations. A comparison between these three codes is performed. These calculated values are important for radiation protection studies and radiotherapy applications.

Comparison of ITO and ZnO ternary glassy composites in terms of radiation shielding properties by Monte Carlo N-particle transport code and BXCOM.

In the present study, radiation shielding properties of two glassy composite materials that are widely used in electronics, photovoltaic applications, and sensor technology, were investigated in the photon energy range from 15 keV to 15 MeV. The materials chosen were (ITO)/V2O5/B2O3 and ZnO/V2O5/B2O3 including various concentrations of B2O3. Radiation interaction was simulated and shielding parameters calculated by means of the MCNP and BXCOM codes. More specifically, buildup factors, effective electron density ([Formula: see text]) and effective atomic number ([Formula: see text]) were calculated with BXCOM, while mass attenuation coefficients ([Formula: see text]), half-value layer (HVL) and tenth-value layer (TVL) values were calculated with MCNP. The results were compared with those obtained with the WinXCOM code, for validation. Acceptable and preferable results were obtained for both composites as alternative to other glassy shielding materials. The composite including ITO showed better shielding properties than the composite including ZnO. In terms of radiation shielding, both composites turned out to be better than concrete and close to lead.

Sensitivity analysis of Monte Carlo model of a gantry-mounted passively scattered proton system.

PURPOSE: This study aimed to present guidance on the correlation between treatment nozzle and proton source parameters, and dose distribution of a passive double scattering compact proton therapy unit, known as Mevion S250. METHODS: All 24 beam options were modeled using the MCNPX MC code. The calculated physical dose for pristine peak, profiles, and spread out Bragg peak (SOBP) were benchmarked with the measured data. Track-averaged LET (LETt ) and dose-averaged LET (LETd ) distributions were also calculated. For the sensitivity investigations, proton beam line parameters including Average Energy (AE), Energy Spread (ES), Spot Size (SS), Beam Angle (BA), Beam Offset (OA), and Second scatter Offset (SO) from central Axis, and also First Scatter (FS) thickness were simulated in different stages to obtain the uncertainty of the derived results on the physical dose and LET distribution in a water phantom. RESULTS: For the physical dose distribution, the MCNPX MC model matched measurements data for all the options to within 2 mm and 2% criterion. The Mevion S250 was found to have a LETt between 0.46 and 8.76 keV.µm-1 and a corresponding LETd between 0.84 and 15.91 keV.µm-1 . For all the options, the AE and ES had the greatest effect on the resulting depth of pristine peak and peak-to-plateau ratio respectively. BA, OA, and SO significantly decreased the flatness and symmetry of the profiles. The LETs were found to be sensitive to the AE, ES, and SS, especially in the peak region. CONCLUSIONS: This study revealed the importance of considering detailed beam parameters, and identifying those that resulted in large effects on the physical dose distribution and LETs for a compact proton therapy machine.

Radiation interaction parameters for blood samples of breast cancer patients: an MCNP study.

The main goal of this study was to determine radiation interaction parameters such as mass attenuation coefficients, effective atomic numbers, and effective electron densities depending on element concentrations (Na, K, Cu, Zn, Al, Ca, Mg Cr, Fe, Se) in blood samples of patients with breast cancer. Eighty blood samples were collected and analyzed in this study (40 from breast cancer patients and 40 from healthy patients). The determination of element concentrations of the samples was performed with inductively coupled plasma-mass spectrometry (ICP-MS) and inductively coupled plasma-optical emission spectrometry (ICP-OES) after which the element concentrations were normalized to percentage. Mass attenuation coefficients were calculated by Monte Carlo simulation method. In addition, effective atomic numbers and effective electron density values of the blood samples were calculated with the ZXCOM program. One of the most important results of this study is that differences in radiation interaction parameters between the two groups were observed. More specifically, the mass attenuation coefficients of the healthy group's blood samples were higher than those of the cancerous group at photon energies of 50 keV, 100 keV, 250 keV and 500 keV, while they were lower at 1 MeV. All the MCNP results were consistent with the results obtained from ZXCOM. As the main result of this study it is concluded that photon atomic parameters such as mass attenuation coefficient, effective atomic number and electron density may be considered in cancer diagnosis or treatment modalities.

Estimation of tumor and local tissue dose in gold nanoparticles radiotherapy for prostate cancer.

AIM: The objective of this research was to estimate the dose distribution delivered by radioactive gold nanoparticles (198AuNPs or 199AuNPs) to the tumor inside the human prostate as well as to normal tissues surrounding the tumor using the Monte-Carlo N-Particle code (MCNP-6.1.1 code). BACKGROUND: Radioactive gold nanoparticles are emerging as promising agents for cancer therapy and are being investigated to treat prostate cancer in animals. In order to use them as a new therapeutic modality to treat human prostate cancer, accurate radiation dosimetry simulations are required to estimate the energy deposition in the tumor and surrounding tissue and to establish the course of therapy for the patient. MATERIALS AND METHODS: A simple geometrical model of a human prostate was used, and the dose deposited by 198AuNPs or 199AuNPs to the tumor within the prostate as well as to the healthy tissue surrounding the prostate was calculated using the MCNP code. Water and A-150 TEP phantoms were used to simulate the soft and tumor tissues. RESULTS: The results showed that the dose due to 198AuNPs or 199AuNPs, which are distributed homogenously in the tumor, had a maximal value in the tumor region and then rapidly decreased toward the prostate-tumor interface and surrounding organs. However, the dose deposited by 198Au is significantly higher than the dose deposited by 199Au in the tumor region as well as normal tissues. CONCLUSIONS: According to the MCNP results, 198AuNPs are a promising modality to treat prostate cancer and other cancers and 199AuNPs could be used for imaging purposes.

Dosimetric comparison between realistic ocular model and other models for COMS plaque brachytherapy with 103Pd, 131Cs, and 125I radioisotopes.

Nowadays, Monte Carlo calculations are commonly used for the evaluation of dose distributions and dose volume histograms in eye brachytherapy. However, currently available eye models have simple geometries, and main substructures of the eye are either not defined in details or not distinguished at all. In this work absorbed doses of eye substructures have been estimated for eye plaque brachytherapy using the most realistic eye model available, and compared with absorbed doses obtained with other available eye models. For this, a medium-sized tumour on the left sides of the right eye was considered. Dosimetry calculations were performed for four different eye models developed based on a literature review, and using a 12 mm Collaborative Ocular Melanoma Study plaque containing 131Cs, 103Pd, and 125I sources. Obtained results illustrate that the estimated doses received by different eye substructures strongly depend on the model used to represent the eye. It is shown here that using a non-realistic eye model leads to a wrong estimation of doses for some eye substructures. For example, dose differences of up to 35% were observed between the models proposed by Nogueira and co-workers and Yoriyaz and co-workers, while doses obtained by use of the models proposed by Lesperance and co-workers, and Behrens and co-workers differed up to 100 and 63% as compared to the situation when a realistic model was used, respectively. Moreover, comparing different radionuclides showed that the most uniform dose distribution in the considered tumour region was that from 131Cs, with a coefficient of variation of 33%. In addition, considering the realistic eye model, it was found that the radiosensitive region of the lens received more than the threshold dose of cataract induction (0.5 Gy), for all investigated radionuclides.

Comparison of neutron organ and effective dose coefficients for PIMAL stylized phantom in bent postures in standard irradiation geometries.

Neutron dose coefficients for standard irradiation geometries have been reported in International Commission on Radiological Protection (ICRP) Publication 116 for the ICRP Publication 110 adult reference phantoms. In the present work, organ and effective dose coefficients have been calculated for a receptor in both upright and articulated (bent) postures representing more realistic working postures exposed to a mono-energetic neutron radiation field. This work builds upon prior work by Dewji and co-workers comparing upright and bent postures for exposure to mono-energetic photon fields. Simulations were conducted using the Oak Ridge National Laboratory's articulated stylized adult phantom, "Phantom wIth Moving Arms and Legs" (PIMAL) software package, and the Monte Carlo N-Particle (MCNP) version 6.1.1 radiation transport code. Organ doses were compared for the upright and bent (45° and 90°) phantom postures for neutron energies ranging from 1 × 10- 9 to 20 MeV for the ICRP Publication 116 external exposure geometries-antero-posterior (AP), postero-anterior (PA), and left and right lateral (LLAT, RLAT). Using both male and female phantoms, effective dose coefficients were computed using ICRP Publication 103 methodology. The resulting coefficients for articulated phantoms were compared to those of the upright phantom. Computed organ and effective dose coefficients are discussed as a function of neutron energy, phantom posture, and source irradiation geometry. For example, it is shown here that for the AP and PA irradiation geometries, the differences in the organ coefficients between the upright and bent posture become more pronounced with increasing bending angle. In the AP geometry, the brain dose coefficients are expectedly higher in the bent postures than in the upright posture, while all other organs have lower dose coefficients, with the thyroid showing the greatest difference. Overall, the effective dose estimated for the upright phantom is more conservative than that for the articulated phantom, which may have ramifications in the estimation or reconstruction of radiation doses.

Comparison of photon organ and effective dose coefficients for PIMAL stylized phantom in bent positions in standard irradiation geometries.

Computational phantoms with articulated arms and legs have been constructed to enable the estimation of radiation dose in different postures. Through a graphical user interface, the Phantom wIth Moving Arms and Legs (PIMAL) version 4.1.0 software can be employed to articulate the posture of a phantom and generate a corresponding input deck for the Monte Carlo N-Particle (MCNP) radiation transport code. In this work, photon fluence-to-dose coefficients were computed using PIMAL to compare organ and effective doses for a stylized phantom in the standard upright position with those for phantoms in realistic work postures. The articulated phantoms represent working positions including fully and half bent torsos with extended arms for both the male and female reference adults. Dose coefficients are compared for both the upright and bent positions across monoenergetic photon energies: 0.05, 0.1, 0.5, 1.0, and 5.0 MeV. Additionally, the organ doses are compared across the International Commission on Radiological Protection's standard external radiation exposure geometries: antero-posterior, postero-anterior, left and right lateral, and isotropic (AP, PA, LLAT, RLAT, and ISO). For the AP and PA irradiation geometries, differences in organ doses compared to the upright phantom become more profound with increasing bending angles and have doses largely overestimated for all organs except the brain in AP and bladder in PA. In LLAT and RLAT irradiation geometries, energy deposition for organs is more likely to be underestimated compared to the upright phantom, with no overall change despite increased bending angle. The ISO source geometry did not cause a significant difference in absorbed organ dose between the different phantoms, regardless of position. Organ and effective fluence-to-dose coefficients are tabulated. In the AP geometry, the effective dose at the 45° bent position is overestimated compared to the upright phantom below 1 MeV by as much as 27% and 82% in the 90° position. The effective dose in the 45° bent position was comparable to that in the 90° bent position for the LLAT and RLAT irradiation geometries. However, the upright phantom underestimates the effective dose to PIMAL in the LLAT and RLAT geometries by as much as 30% at 50 keV.

Radiation shielding analysis of a special linear accelerator for electron beam and X-ray.

The King AbdulAziz City for Science & Technology in the Kingdom of Saudi Arabia plans to build a 10 MeV, 15 kW linear accelerator (LINAC) for electron beam and X-ray. The accelerator will be supplied by EB Tech, Republic of Korea, and the design and construction of the accelerator building will be conducted in the cooperation with EB Tech. This report presents the shielding analysis of the accelerator building using the Monte Carlo N-Particle Transport Code (MCNP). In order to improve the accuracy in estimating deep radiation penetration and to reduce computation time, various variance reduction techniques, including the weight window (WW) method, the deterministic transport (DXTRAN) spheres were considered. Radiation levels were estimated at selected locations in the shielding facility running MCNP6 for particle histories up to 1.0×10+8. The final results indicated that the calculated doses at all selected detector locations met the dose requirement of 50 mSv/yr, which is the United State Nuclear Regulatory Commission (U.S. NRC) requirement.

The effect of gamma irradiation on the properties of cucumber.

In this study, the effect of gamma irradiation on the shelf life and properties of cucumber was investigated. These properties include weight reduction, fruit density, juice, tissue firmness, total soluble solids (TSS), total titratable acidity, chlorophyll and vitamin C, pH, marketability, flavor, frostbite and fungal effects. For this purpose, cucumbers were irradiated with dose of 2, 2.5 and 3 kGy. The exposure time was calculated by MCNP4C; the Monte Carlo particle transport code. Three types of fungi (white-Sclerotinia sclerotiorum, gray-Botrytis cinerea and olive-Cladosporium cucumerinum), were used to infect some samples. The chlorophyll and vitamin C preservation abilities were increased to about 3 and 1.4 times, respectively with irradiation treatment. Also, the shelf life was increased about 1 week, while chilling injuries is decreased. Samples' resistance to the fungal growth was evident and the process of fungal growth on the irradiated samples was delayed up to 1 week. The best properties were obtained at the irradiation dose of 2 kGy since it had less effect on flavor, TSS and tissue firmness.

Dosimetric intercomparison of permanent Ho-166 seed's implants and HDR Ir-192 brachytherapy in breast cancer.

AIM: To provide a comparative dosimetric analysis of permanent implants of Ho(166)-seeds and temporary HDR Ir(192)-brachytherapy through computational simulation. BACKGROUND: Brachytherapy with Ir(192)-HDR or LDR based on temporary wires or permanent radioactive seed implants can be used as dose reinforcement for breast radiation therapy. Permanent breast implants have not been a practical clinical routine; although, I(125) and Pd(103)-seeds have already been reported. Biodegradable Ho(166)-ceramic-seeds have been addressed recently. MATERIAL AND METHODS: Simulations of implants of nine Ho(166)-seeds and equivalent with HDR Ir(192)-brachytherapy were elaborated in MCNP5, shaped in a computational multivoxel simulator which reproduced a female thorax phantom. Spatial dose rate distributions and dose-volume histograms were generated. Protocol's analysis involving exposure time, seed's activities and dose were performed. RESULTS: Permanent Ho(166)-seed implants presented a maximum dose rate per unit of contained activity (MDR) of 1.1601 µGy h(-1) Bq(-1); and, a normalized MDR in standard points (8 mm, equidistant to 03-seeds - SP1, 10 mm - SP2) of 1.0% (SP1) and 0.5% (SP2), respectively. Ir(192)-brachytherapy presented MDR of 4.3945 × 10(-3) µGy h(-1) Bq(-1); and, 30% (SP1), and 20% (SP2). Therefore, seed's implant activities of 333 MBq (Ho(166)) and 259 GBq (Ir(192)) produced prescribed doses of 58 Gy (SP1; 5d) and 56 Gy (SP1, 5 fractions, 6 min), respectively. CONCLUSIONS: Breast Ho(166)-implants of 37-111 MBq are attractive due to the high dose rate near 6-10 mm from seeds, equivalent to Ir(192)-brachytherapy of 259 GBq (3 fractions, 6 min) providing similar dose in standard points at a week; however, with spatial dose distribution better confined. The seed positioning can be adjusted for controlling the breast tumor, in stages I and II, in flat and deep tumors, without any breast volumetric limitation.

A pilot study of diabetes effects on radiation attenuation characteristics of tibia and femur of rats.

This study aimed to investigate the effect of diabetes on radiation attenuation parameters of the femur and tibia of rats using Monte Carlo Simulations. First, control and diabetic rats were identified and tibias and femurs were removed. Then, the elemental ratios of the bones obtained were calculated using EDS (Energy Dissipative X-ray Spectroscopy). Therefore, radiation permeability properties of control and diabetic bones were simulated by using the content ratios in the bones in MCNP6 (Monte Carlo N-Particle) and PHITS (Particle and Heavy Ion Transport code System) 3.22 and Stopping and Range of Ions in Matter (SRIM) simulation codes. Attenuation coefficient results were compared with the NIST database via XCOM. Although differences in absorption coefficients are observed at low energies, these differences disappear as the energy increases.