Evaluation of boron neutron capture therapy in-phantom parameters by response matrix method.

AIM: Determination of boron neutron capture therapy in-phantom parameters by response matrix (RM) method. MATERIALS AND METHODS: In this study, various in-phantom figures-of-merit including therapeutic gain, advantage depth dose rate, advantage depth, therapeutic depth, treatment time, skin dose rate, and skull dose rate have been analyzed using the RM method. This method is based on the division of neutron/gamma spectrum and calculation of various dose components of each energy group. Summation of these dose responses is equal to the total dose of the whole spectrum. Based on this method, in-phantom parameters could be calculated by a computer program in a very short time. RESULTS: There is a good agreement between direct calculation and RM method. The maximum allowable contaminations of the thermal and fast neutrons in a neutron beam have been calculated by RM method. It was found that these values are 17.4% and 2.6%, for thermal and fast neutron, respectively. CONCLUSION: The results confirm that the RM method is a fast method to evaluate in-phantom parameters without repeating simulations due to change in neutron spectrum and treatment conditions.

Measurement of in-phantom neutron flux and gamma dose in Tehran research reactor boron neutron capture therapy beam line.

AIM: Determination of in-phantom quality factors of Tehran research reactor (TRR) boron neutron capture therapy (BNCT) beam. MATERIALS AND METHODS: The doses from thermal neutron reactions with 14N and 10B are calculated by kinetic energy released per unit mass approach, after measuring thermal neutron flux using neutron activation technique. Gamma dose is measured using TLD-700 dosimeter. RESULTS: Different dose components have been measured in a head phantom which has been designed and constructed for BNCT purpose in TRR. Different in-phantom beam quality factors have also been determined. CONCLUSIONS: This study demonstrates that the TRR BNCT beam line has potential for treatment of superficial tumors.

Natural radionuclide and radiological assessment of building materials in high background radiation areas of Ramsar, Iran.

Building materials, collected from different sites in Ramsar, a northern coastal city in Iran, were analyzed for their natural radionuclide contents. The measurements were carried out using a high resolution high purity Germanium (HPGe) gamma-ray spectrometer system. The activity concentration of (226)Ra, (232)Th, and (40)K content varied from below the minimum detection limit up to 86,400 Bqkg(-1), 187 Bqkg(-1), and 1350 Bqkg(-1), respectively. The radiological hazards incurred from the use of these building materials were estimated through various radiation hazard indices. The result of this survey shows that values obtained for some samples are more than the internationally accepted maximum limits and as such, the use of them as a building material pose significant radiation hazard to individuals.