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.
Fatemeh Sadat Rasouli
Abstract
Among the approaches commonly used to extend the sharp peak of the deposited dose in proton therapy, passive scattering is widely used and also is of concern because of the potential for generating secondary particles, especially neutrons, which can damage the non-target healthy tissues. The present ...
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Among the approaches commonly used to extend the sharp peak of the deposited dose in proton therapy, passive scattering is widely used and also is of concern because of the potential for generating secondary particles, especially neutrons, which can damage the non-target healthy tissues. The present simulation-based study investigates the effect of using the passive method for different primary proton energies on the dose delivered to the tissue compared with those of the pencil beam scanning method. The results show that the generation of secondary neutrons strongly depends on the material used in the beam design. Also, it was found that the passive method would lead to the physical neutron dose higher than that of the beam scanning method for various primary proton energies.
