Author: Xiaoda Cong, Xuanfeng Ding, Gang Liu, Peilin Liu, Jiajian Shen 👨🔬
Affiliation: Department of Radiation Oncology, Mayo Clinic, Cancer Center, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Corewellhealth William Beaumont University Hospital 🌍
Purpose: This study aims to develop the first SPArc optimization algorithm based on the Dynamic Programming (SPArc-DP), to improve the treatment delivery efficiency for synchrotron-accelerator-based Proton Therapy Systems with the Single Energy Extraction (SEE) technique (PTS-synchrotron-SEE.)
Methods: Dynamic Programming, initially designed for combinational optimizations in fields of bioinformatics, finance and scheduling, was introduced to optimize the energy layer and MU distribution based on the features from the PTS-synchroton-SEE. It started from a plan generated via the original SPArc algorithm (SPArc-original). Based on the maximum charges per extraction, it iteratively merges the adjacent energy layers into the same energy layer while ensuring the plan quality. Thus, it effectively reduces the unnecessary cycling from the PTS-synchroton-SEE. Five representative disease sites are selected for testing purposes, including the base of skull chordoma, bilateral HN, prostate, lung, and liver cancers. The SPArc-original plans are used as benchmarks. Dosimetric metrics, including target dose conformity index (CI), target coverage, and OARs sparing, were evaluated, and the total number of cycles, utilization rate of each spill, and total treatment delivery time were simulated and compared between SPArc-original and SPArc-DP using a dynamic arc system controller.
Results: With a similar plan quality, the SPArc-DP plans reduced the number of acceleration cycles by an average of 118.80 ± 72.15, or 237.60 ± 144.31s reduction in the total cycling time compared to SPArc-original plans. These improvements effectively saved total treatment delivery time by 239.67s ± 218.15s (relatively 43% ± 13%) compared to SPArc-original plans.
Conclusion: The study introduced the first SPArc optimization algorithm for the PTS-synchrotron-SEE. With a similar plan quality, the treatment delivery time could be significantly reduced on various disease sites, which paves the roadmap to implement the SPArc technique.