Dose and irradiation time analysis of negative pi-meson therapy using particle and heavy ion transport code system (PHITS)

Minimizing the radiation side effects in cancer therapy has become one of the major challenges in radiotherapy, especially if the cancer is located in vital organs such as the brain. Negative pi-meson-based therapy is one method of radiotherapy that allows cancer to receive a high radiation dose while the surrounding normal tissue receives a low radiation dose. This research aims to analyze negative pi-meson therapy's dose and irradiation time in glioblastoma multiforme.

Simulation-based research is conducted using the PHITS program. The source used is a negative pion beam with an intensity of 2.5 × 108 pions/second with an energy of 30 MeV to 60 MeV with an interval of 1 MeV. The negative pion energy, which has the maximum dose rate in the cancer target area, was optimized to obtain the weighting factors and irradiation time. The irradiation was carried out in 30 fractions with the dose per fraction of 2 Gy.

Irradiation time per fraction obtained was 194.91 seconds. The organ at risks (OARs) analyzed in this research were soft tissue, skin, brain, and cervical spinal cord. The doses received by the OAR are 0.2641 Gy, 0.7645 Gy, 7.3295 Gy, and 0.075 Gy, respectively.

In summary, negative pi-meson therapy has the potential to minimize radiation dose to healthy tissue while cancer still receives high-dose radiation. However, it is necessary to compare negative pi-meson therapy and other radiotherapy methods to determine the strengths and weaknesses of each method.