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.

A Monte Carlo simulation for studying grid inefficiency of Frisch grid ionization chamber.

The grid inefficiency (GI) of Frisch grid ionization chambers (FGICs) must be considered in the case of accurate energy measurements. A Monte-Carlo model has been developed based on the Garfield and SRIM toolkits to investigate the GI of FGIC. It could simulate the charge signals from different electrodes without considering the electrical noises and random effects in the experiments. Computations made with the weighting potential and charge signals of FGIC exemplify the possibilities of this model. The GI values obtained with different methods showed the difference among the existing approaches in the literature. In addition, the results of homogeneous deformations of one wire over one grid period showed that deformation in the grid plane caused more distortion on GI than that perpendicular to the grid plane. An individual experiment was also carried out with a compound alpha source (241Am and 243Am) to validate the feasibility of this model. The results showed that the raw pulses and GI values obtained from the simulation agreed well with those measured from the experiment. The present work showed that this Monte-Carlo model could be well applied to investigate such type of detector, which could provide great conveniences for future work to measure the total kinetic energy of the fission fragments.

A theoretical study for the production of 32P radioisotope using neutrons from the 68Zn(p,n)68Ga reaction in a medical cyclotron.

In the present study, the theoretical estimation of a combined production of 68Ga and 32P radioisotopes were investigated using a medical cyclotron. Protons are used in the 68Zn(p,n) reaction to produce the medical isotope 68Ga. The neutrons from the 68Zn(p,n)68Ga reaction are used to launch the 32S(n,p) reaction to produce 32P radioisotope. The cross section of these reactions were calculated using TALYS 1.9 code and compared with the available experimental results. SRIM-2013 code was used to calculate the stopping power and range of protons in the 68Zn target and GEANT4 toolkit was used to evaluate the proton and neutron flux within the 68Zn and 32S targets, respectively. The theoretical and simulation production yield of 68Ga and simulation production yield of 32P radioisotopes in each reaction were calculated. The results show that the Monte Carlo method can be used for the design and optimization the targets and calculation of production yield for 68Ga and 32P radioisotopes.

Construction and evaluation of an α-particle-irradiation exposure apparatus.

PURPOSE: The development of an exposure apparatus for in situ α-irradiation studies of cells. The construction of the apparatus is simple and the apparatus is maintenance free, easy to use and of low cost. This small device can be placed in an incubator, where the exposure environment is controlled. Moreover the vapor saturated incubator protects the cells from drying out, allowing long irradiation intervals. MATERIALS AND METHODS: The system includes a 234U alpha (α)-source of total activity 0.77 ± 0.03 MBq in the form of a thin disk deposited on an aluminum substrate. The α-particles emitted in the air have a mean energy of 4.9 MeV at the disk surface. Source homogeneity has been studied via Rutherford Backscattering Spectrometry. Using SRIM 2013 and Monte Carlo (MC) simulations via the MCNP6.1 code, LET and energy deposition values have been calculated for various filling gasses. Furthermore, based on these simulations, the assembly's dimensions and equivalent irradiation rate have been determined. With respect to the aforementioned dimensions, the experimental setup is constructed in a way to provide uniform irradiation of the sample. Using Sacalc3v1.4 irradiation radial homogeneity has been studied. In order to evaluate biologically our apparatus, a well-established chromosomal aberration assay has been utilized, applied in exponentially growing hamster (CHO) cells. Furthermore, immunofluorescence gamma-H2AX/53BP1 foci assay has been performed as a 'biological detector', in order to validate α-particles surface density. RESULTS: Source surface homogeneity: emission deviations do not exceed 10-15%. The optimal distance between the source and the cells for irradiation is determined to be 14.8 mm. Irradiation radial homogeneity: a deviation of 5% occurs at the first 8 mm from the center of the irradiation area, and a 10% deviation occurs after 12 mm. Chromosomal aberrations were found in good agreement with the corresponding in bibliography. CONCLUSIONS: The current technical report describes analytically the development and evaluation stages of this experimental housing; from MC simulations to the irradiation of mammalian cells and data analysis. Moreover, guidance is provided as well as a report of the variables on which critical parameters are depended, so as to make this work useful to anyone who wants to construct a similar in-house α-irradiation apparatus for radiobiological studies using mammalian cells.