Liang Xiaoying, Beltran Chris J, Liu Chunbo, Park Chunjoo, Lu Bo, Yaddanapudi Sridhar, Tan Jun, Furutani Keith M
Department of Radiation Oncology, Mayo Clinic, Jacksonville, FL 32224, USA.
Department of Radiation Oncology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou 450052, China.
Cancers (Basel). 2023 Aug 13;15(16):4084. doi: 10.3390/cancers15164084.
Pencil beam scanning delivered with continuous scanning has several advantages over conventional discrete spot scanning. Such advantages include improved beam delivery efficiency and reduced beam delivery time. However, a move dose is delivered between consecutive spots with continuous scanning, and current treatment planning systems do not take this into account. Therefore, continuous scanning and discrete spot plans have an inherent dose discrepancy. Using the operating parameters of the state-of-the-art particle therapy system, we conducted a proof-of-concept study in which we systematically generated 28 plans for cubic targets with different combinations of plan parameters and simulated the dose discrepancies between continuous scanning and a planned one. A nomograph to guide the selection of plan parameters was developed to reduce the dose discrepancy. The effectiveness of the nomograph was evaluated with two clinical cases (one prostate and one liver). Plans with parameters guided by the nomograph decreased dose discrepancy than those used standard plan parameters. Specifically, the 2%/2 mm gamma passing rate increased from 96.3% to 100% for the prostate case and from 97.8% to 99.7% for the liver case. The CTV DVH root mean square error decreased from 2.2% to 0.2% for the prostate case and from 1.8% to 0.9% for the liver case. The decreased dose discrepancy may allow the relaxing of the delivery constraint for some cases, leading to greater benefits in continuous scanning. Further investigation is warranted.
连续扫描的笔形束扫描相对于传统的离散点扫描具有多个优点。这些优点包括提高射束传输效率和减少射束传输时间。然而，连续扫描在连续的点之间会传递移动剂量，而当前的治疗计划系统并未考虑到这一点。因此，连续扫描和离散点计划存在固有的剂量差异。利用最先进的粒子治疗系统的运行参数，我们进行了一项概念验证研究，在该研究中，我们系统地为立方靶标生成了28个具有不同计划参数组合的计划，并模拟了连续扫描与计划扫描之间的剂量差异。开发了一种用于指导计划参数选择的列线图，以减少剂量差异。通过两个临床病例（一个前列腺病例和一个肝脏病例）评估了列线图的有效性。由列线图指导参数的计划比使用标准计划参数的计划减少了剂量差异。具体而言，前列腺病例的2%/2毫米伽马通过率从96.3%提高到100%，肝脏病例从97.8%提高到99.7%。前列腺病例的CTV剂量体积直方图均方根误差从2.2%降至0.2%，肝脏病例从1.8%降至0.9%。剂量差异的降低可能会使某些病例的传输约束得到放宽，从而在连续扫描中带来更大的益处。有必要进行进一步的研究。
