Analysis of Proton Radiotherapy Dose Distribution in Pediatric Medulloblastoma Cases Using MCNP 6.2.0

Proton radiotherapy is a new modality that has the potential to treat tumors to therapeutic levels. Proton sources are superior to photons for radiotherapy because the maximum dose is distributed over the tumor target and minimally affects healthy tissue. Proton radiotherapy has the potential to be used in pediatric tumor cases, one of which is in the treatment of medulloblastoma in children aged 10 years. The use of clinical proton radiotherapy is still very small, so treatment planning in this study used the Monte Carlo simulation method. This research was conducted to determine the target dose distribution to the tumor and healthy tissue around the cancer. This research uses the Monte Carlo N -Particle (MCNP) 6.2.0 program to run the simulation. The proton radiotherapy simulation uses a benchmarking nozzle from previous research taken from the Nozzle Everything Upstream (NEU) program, as well as using a 10 -yearold whole -body Oak Ridge National Laboratory -Medical Internal Radiation Dose (ORNL -MIRD) phantom. The ORNL -MIRD phantom is illuminated by protons from the posterior direction and then the dose is calculated. The simulation dose calculation is set on the MCNP tally. The research resultsshowed that the dose distribution in the Clinical Target Volume (CTV) was (19.82 ± 0.099) Gy RBE and the Planning Target Volume (PTV) was (18.07 ± 0.072) Gy RBE.In addition, the brain, skull and spinal cord as OAR received a relative dose percentage to the tumor of 4.64%, 1.58% and 0.0607% respectively.In this study, proton radiotherapy in the treatment of brain tumors was get the dose distribution to therapeutic levels.