RESUMEN
Monte Carlo method is a very accurate method to optimize medical diagnostic radiology spectra and simulation of radiation transportation. Using MCNP code, radiology and mammography attenuated x-rayspectraweresimulated.The IPEM report number 78 was used as a reference to compare with the GEANT4 and MCNP simulations because of its popularity and wide availability. The results of GEANT4 in 40keV showed a good homogeneity with IPEM report in terms of intensity, whilst the MCNP code in tube voltage 150kVp showed a very good agreement. Whereas theGEANT4outputintensityinallcases was less than the IPEM report, MCNP code showed higher characteristic peak intensity. The MCNP results were obtained with a less error percentage in comparison with IPEM reportexceptatlowenergies. The comparison shows a good agreement between these two codes. MCNP shows a very goodagreement in high tube voltage whereas GEANT4 showsvery goodagreement in low tube voltage
RESUMEN
Chlorotoxin is a 36 amino acids peptide, which is able to block chloride channels isolated from mouse brain. A derivative of chlorotoxin is synthesized and it is labeled by iodine 131; then animal experiments carry out on rats. Multiple organ doses may be calculated with biological distribution results in rats with labeled compounds using simulated MCNP4C code. Human dose can be calculated using the dose distribution in rats with a conversion ratio for dose distribution. Chloramine T is our method for marking, and electrophilic substitution reactions are methods for iodize of peptides. Simulation of a human phantom to evaluate dose distribution was done using simulation code MCNP4C. To evaluate the dose distribution in the human body, using this code and the accumulated activity in each organ tissue dose is calculated. To study the biological distribution of the radiotracer 131I, 0.37 MBq radiotracer was injected into rat via the tail vein. The accumulated activity in each organ with the agent "ID / g" is determined. Biological distribution of 131I-chlorotoxine in the normal rats is obtained. Its Decay constant in the liver is 0.07h and the effective half-life of the radiotracer is 10h in rat liver. The total number of particles found in the leak from liver tissue was reported 67600. Liver tissue dosimetries originating from other sources [thyroid tissue, stomach, kidney, right and left lung, spleen, and pancreas] were examined. Then, the overall dose to the target tissue will be calculated. Leaked beta particles in liver itself [self-dose] are the most delivered dose to the liver [98%]; it is for gamma rays 1.1%, while its source is adjacent tissues in addition to liver [cross-dose]; Because of low atomic number of the tissue, delivered dose originated from Bremsstrahlung [braking radiation] is low [0.9%]. Radiation dose to the liver in intravenous injection of 0.37 MBq [131]I-chlorotoxine radiotracer is 3.44 [asterisk] 10-6
RESUMEN
Naturally occurring radionuclides have different amount of activity concentration for [226] Ra, [232]Th and [40]K in building materials. In this study, natural radioactivity has been measured for bricks used in Tehran. For this work, 9 samples of three types of bricks, clay brick [CB], making the facade brick [MFB] and firebrick [FB] has been selected from different regions and factories in Tehran. Gamma rays analyzed by high purity germanium [HPGe] detector and spectroscopy system. As the results show, the maximum value of the mean [226] Ra, [232]Th and [40]K for clay brick has been 17, 9 and 422Bq/kg respectively. Maximum of radium equivalent activities [Ra[eq]] were calculated 62.81Bq/kg that less than the level has been determined 370Bq/kg for building materials. Other type of bricks had low amounts compared to clay bricks. The calculation results show that the bricks are safe for inhabitants because hazard indexes for gamma were below the standard was been introduced. The results of this research compared with other studies in different countries