Liu Peilin, Cong Xiaoda, Liang Jian, Xu Xiangkun, Zheng Weili, Stevens Craig, Deraniyagala Rohan, Li Xiaoqiang, Ding Xuanfeng
Department of Radiation Oncology, Corewell Health William Beaumont University Hospital, Royal Oak, MI, USA.
Int J Part Ther. 2025 Apr 20;16:100749. doi: 10.1016/j.ijpt.2025.100749. eCollection 2025 Jun.
Dynamic Spot-scanning Proton Arc (SPArc) therapy has gained attention for enhancing dosimetric plan quality. However, its full clinical implementation remains under development. As an interim milestone, we developed step-and-shoot arc therapy (SPArc) for head-neck cancer treatment.
An in-house spot and energy-layer sparsity optimization algorithm was integrated into a clinical treatment planning system. The algorithm prioritized higher MU-weighted energy layers and spots to ensure delivery efficiency and superior plan quality while meeting machine requirements (≥0.02MU/spot). A Dynamic SPArc simulator calculated delivery times, and a machine-learning-based synthetic CT(synCT) platform monitored dose robustness. In June 2024, a head-neck cancer patient with parotid gland malignancy was treated using SPArc (6600 cGy[relative biological effectiveness] in 33 fx) with 9 static fields at 20-degree intervals. Comparative plans (SFO-IMPT, SPArc) were evaluated for dose metrics, delivery times, and adaptive planning.
SPArc and SPArc showed similar target coverage and organ-at-risks sparing, and the plan quality is superior to the 3-field SFO-IMPT in the brainstem, oral cavity, and spinal cord sparing. The simulated continuous arc delivery time is 15.9, 6.32, and 4.31 minutes for SPArc SFO-IMPT, and SPArc, respectively. The actual recorded average treatment delivery time for SPArc in 33 fx is 16.7 ± 1.56 minutes. QA-CT and synCT showed a similar target coverage degradation and perturbation, and a replan was initiated.
The SPArc therapy was successfully implemented in the clinical settings, and first patient was successfully treated between June and August 2024. The synCT platform serves a critical role in the daily monitoring process as SPArc might be more sensitive to the patient geometry changes in HNC treatment.
动态点扫描质子弧形（SPArc）治疗因能提高剂量计划质量而受到关注。然而，其全面临床应用仍在开发中。作为一个中期里程碑，我们开发了用于头颈癌治疗的步进式弧形治疗（SPArc）。
将一种内部点和能量层稀疏优化算法集成到临床治疗计划系统中。该算法优先考虑更高MU加权的能量层和点，以确保在满足机器要求（≥0.02MU/点）的同时实现输送效率和卓越的计划质量。动态SPArc模拟器计算输送时间，基于机器学习的合成CT（synCT）平台监测剂量稳健性。2024年6月，一名患有腮腺恶性肿瘤的头颈癌患者接受了SPArc治疗（33次分割，6600 cGy[相对生物效应]）；采用9个静态野，间隔20度。对比较计划（SFO-IMPT、SPArc）进行剂量指标、输送时间和自适应计划评估。
SPArc和SPArc显示出相似的靶区覆盖和危及器官的保护，且在脑干、口腔和脊髓保护方面，该计划质量优于三野SFO-IMPT。对于SPArc、SFO-IMPT和SPArc，模拟的连续弧形输送时间分别为15.9分钟、6.32分钟和4.31分钟。SPArc在33次分割中的实际记录平均治疗输送时间为16.7±1.56分钟。QA-CT和synCT显示出相似的靶区覆盖降解和扰动，并启动了重新计划。
SPArc治疗已在临床环境中成功实施，首例患者于2024年6月至8月成功接受治疗。synCT平台在日常监测过程中发挥着关键作用，因为在头颈癌治疗中，SPArc可能对患者几何形状变化更为敏感。
