A new ridge filter design for PBS-IMPT: part II

Background Building upon previous research, this study further enhances the RF design, significantly improving its dose modulation capability and treatment efficiency. Methods A PTV-based optimization method (Monte Carlo calculation + IPOPT solver) was used to first create a standard IMPT plan as reference. RF hexagon was then assembled based on the optimized spot weights according to the new design method. The dose distribution through the RF was compared with that of the reference plan and previous work to validate the new design. The study also evaluated the modulation capability of RF in a simultaneous integrated boost (SIB) plan and analyzed relevant FLASH parameters (DADR, total treatment duration). Results For both the standard IMPT plan and the simultaneous boost plan, the dose distribution through RF hexagon was highly comparable to the reference, with gamma passing rates exceeding 0.97. Compared to previous work (RF square), the RF hexagon shows a closer similarity to the reference. The entire PTV and ~ 85% of the oar volume received DADRs higher than 40 Gy/s when the beam intensity reached 1.0 × 10 ¹⁰ protons/s. When the beam intensity surpassed \(\:5\times\:{10}^{11}\) protons/s, the total treatment time was reduced to less than 2.66 second. Conclusion Compare to previous work, the new RF design can significantly improve its dose modulation capability and enhance treatment efficiency. Additionally, the RF’s performance in the simultaneous boost plan proves that the new design possesses strong modulation capabilities.