Investigation the Performance Accuracy of Contoured Dual Ring Double Scatterer System for Flat Beam Generation at Proton Therapy.

Background: At proton radiotherapy, the extracted beam from accelerator is not initially suitable for tumor treatment and a modification is needed for beam shape and energy due to tumor dimension and site. One clinical strategy is the use of double scattering systems known as passive dose delivery technique to generate proper flattening, transversely.

Objective: This work aims to design and simulate a new version of double scattering system and compare its performance with another available scatterer system, quantitatively.

Material and methods: In this analytical study, Monte Carlo FLUKA code is utilized to simulate the performance of proposed system in generating lateral flat beam. The simulation process is very close to real experimental condition, performed at proton beam irradiation room at Tohoku University in Japan. Moreover, the presence of secondary neutrons, produced due to protons collision with proposed scattering system, is considered as main issue.

Results: Final results represent that the proposed scattering system is robust to generate 40 mm flat region with an acceptable uniformity degree. Energy loss caused by current dual scatterer is more than simple ring technique, while the secondary neutrons produced by proposed system are larger than other system.

Conclusion: This study simulates the performance of a new dual ring double scattering system. Final results show that there is a close correlation between proposed system and current scattering system. The only concern is about the presence of secondary neutrons mainly at high energy proton particles.