Department of Radiation Oncology, Kanagawa Cancer Center, Yokohama, Kanagawa, Japan.
Department of Radiation Oncology, Gunma University Graduate School of Medicine, Maebashi, Gunma, Japan.
J Appl Clin Med Phys. 2021 Jun;22(6):130-138. doi: 10.1002/acm2.13275. Epub 2021 May 27.
We analyzed interfractional robustness of scanning carbon ion radiotherapy (CIRT) for prostate cancer based on the dose distribution using daily in-room computed tomography (CT) images.
We analyzed 11 consecutive patients treated with scanning CIRT for localized prostate cancer in our hospital between December 2015 and January 2016. In-room CT images were taken under treatment conditions in every treatment session. The dose distribution on each in-room CT image was recalculated, while retaining the pencil beam arrangement of the initial treatment plan. Then, the dose-volume histogram (DVH) parameters including the percentage of the clinical target volume (CTV) with 95% and 90% of the prescribed dose area (V95% of CTV, V90% of CTV) and V80% of rectum were calculated. The acceptance criteria for the CTV and rectum were set at V95% of CTV ≥95%, V90% of CTV ≥98%, and V80% of rectum < 10 ml.
V95% of CTV, V90% of CTV, and V80% of rectum for the reproduced plans were 98.8 ± 3.49%, 99.5 ± 2.15%, and 4.39 ± 3.96 ml, respectively. Acceptance of V95% of CTV, V90% of CTV, and V80% of rectum was obtained in 123 (94%), 125 (95%) and 117 sessions (89%), respectively. Acceptance of the mean dose of V95% of CTV, V90% of CTV, and V80% of rectum for each patient was obtained in 10 (91%), 10 (91%), and 11 patients (100%), respectively.
We demonstrated acceptable interfractional robustness based on the dose distribution in scanning CIRT for prostate cancer.
我们基于使用每日治疗室内计算机断层扫描（CT）图像的剂量分布，分析前列腺癌碳离子放疗（CIRT）的分次间稳健性。
我们分析了 2015 年 12 月至 2016 年 1 月期间在我院接受扫描 CIRT 治疗的 11 例局限性前列腺癌患者。在每个治疗疗程中，均在治疗条件下拍摄治疗室内 CT 图像。在保留初始治疗计划的铅笔束排列的情况下，重新计算每个治疗室内 CT 图像上的剂量分布。然后，计算包括临床靶区（CTV）体积 95%和 90%处方剂量区域（CTV 体积 95%，CTV 体积 90%）和直肠 80%体积（V80%直肠）的剂量-体积直方图（DVH）参数。CTV 和直肠的接受标准设定为 CTV 体积 95%≥95%，CTV 体积 90%≥98%，直肠 80%<10ml。
重现计划的 CTV 体积 95%、CTV 体积 90%和直肠 80%分别为 98.8±3.49%、99.5±2.15%和 4.39±3.96ml。123 次（94%）、125 次（95%）和 117 次（89%）分别获得了 CTV 体积 95%、CTV 体积 90%和直肠 80%的接受标准。10 例（91%）、10 例（91%）和 11 例（100%）患者的 CTV 体积 95%、CTV 体积 90%和直肠 80%的平均剂量接受标准。
我们在前列腺癌扫描 CIRT 中基于剂量分布证明了可接受的分次间稳健性。
