Westdeutsches Protonentherapiezentrum Essen, Germany.
J Appl Clin Med Phys. 2012 May 10;13(3):3639. doi: 10.1120/jacmp.v13i3.3639.
Proton radiotherapy of the prostate basal or whole seminal vesicles using scattering delivery systems is an effective treatment of prostate cancer that has been evaluated in prospective trials. Meanwhile, the use of pencil beam scanning (PBS) can further reduce the dose in the beam entrance channels and reduce the dose to the normal tissues. However, PBS dose distributions can be affected by intra- and interfractional motion. In this treatment planning study, the effects of intra- and interfractional organ motion on PBS dose distributions are investigated using repeated CT scans at close and distant time intervals. The minimum dose (Dmin) and the dose to 2% and 98% of the volumes (D2% and D98%), as well as EUD in the clinical target volumes (CTV), is used as measure of robustness. In all patients, D98% was larger than 96% and D2% was less than 106% of the prescribed dose. The combined information from Dmin, D98% and EUD led to the conclusion that there are no relevant cold spots observed in any of the verification plans. Moreover, it was found that results of single field optimization are more robust than results from multiple field optimizations.
使用散射递送系统对前列腺基底或整个精囊进行质子放疗是一种有效的前列腺癌治疗方法，已在前瞻性试验中进行了评估。同时，使用铅笔束扫描（PBS）可以进一步降低射束入口通道中的剂量，并降低对正常组织的剂量。然而，PBS 剂量分布可能会受到内部分裂和分次间运动的影响。在这项治疗计划研究中，使用近距离和远距离时相的重复 CT 扫描研究了器官内部分裂和分次间运动对 PBS 剂量分布的影响。临床靶区（CTV）中的最小剂量（Dmin）和体积的 2%和 98%的剂量（D2%和 D98%）以及 EUD 被用作稳健性的衡量标准。在所有患者中，D98%均大于处方剂量的 96%，D2%均小于 106%。Dmin、D98%和 EUD 的综合信息表明，在任何验证计划中均未观察到相关冷点。此外，还发现单野优化的结果比多野优化的结果更稳健。
