Leyli Mogheiseh; Ali Asghar Mowlavi; Sayyed Bijan Jia; Reza Shamsabadi
Abstract
Proton therapy of liver tumors can be challenging due to the absorbed dose of produced secondary particles in non-target organs. This study aims to evaluate the absorbed dose of secondary particles during the proton therapy of liver cancer through the MCNPX Monte Carlo (MC) code by a simplified MIRD-UF ...
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Proton therapy of liver tumors can be challenging due to the absorbed dose of produced secondary particles in non-target organs. This study aims to evaluate the absorbed dose of secondary particles during the proton therapy of liver cancer through the MCNPX Monte Carlo (MC) code by a simplified MIRD-UF standard phantom. At first, a simplified MC model of MIRD-UF standard phantom was simulated using MCNPX. After the proper proton energies calculation ranging from 90 to 120 MeV for 4×4×4 cm3 tumor irradiation, mesh tally type 3 and F6 tally were used to calculate the depth dose profiles as well as the absorbed dose of protons and secondary particles in non-involved organs. The obtained results illustrated that the fluence of internal secondary particles doses was considerably small in comparison with primary protons. Furthermore, most of neutrons and photons doses were absorbed around the liver tissue for all performed proton energies (i.e., 90 and 120 MeV) which non-target organs did not receive a significant high dose. Furthermore, the absorbed dose of secondary photons and neutrons had slight variations in considered normal tissues near the liver. The calculated results in this study indicated that during the proton therapy of liver cancer, the most contribution of the secondary particle doses was absorbed inside the liver tissue. Hence, it can be expected the probable side effects (secondary cancers) associated with the liver cancer proton therapy may be decreased however, the presence of secondary particles should not be ignored.
Milad Payandeh; Mahdi Sadeghi; Dylan Richeson; Somayeh Gholami
Abstract
It is important to have accurate information regarding the dose distribution for treatment planning and to accurately deposit that dose in the tissue surrounding the brachytherapy source. However, the practical measurement of dose distribution for various reasons is associated with several problems. ...
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It is important to have accurate information regarding the dose distribution for treatment planning and to accurately deposit that dose in the tissue surrounding the brachytherapy source. However, the practical measurement of dose distribution for various reasons is associated with several problems. In this study, 6711 I-125, Micro Selectron mHDR-v2r Ir-192, and Flexisource Co-60 sources were simulated using the MCNP5 Monte Carlo method. To simulate the sources, the exact geometric characteristics of each source, the material used in them, and the energy spectrum of each source were entered as input to the program, and finally, the dosimetric parameters including dose rate constant, radial dose function, and anisotropy function were calculated for considered seeds according to AAPM, TG-43 protocol recommendation. Results obtained for dosimetric parameters of dose rate constant, radial dose function, and anisotropy function for I-125, Ir-192, and Co-60 sources agreed with other studies. According to the good agreement obtained between the parameters of TG43 and other studies, now these datasets can be used as input in the treatment planning systems and to validate their calculations.
