Zeng Chuan, Sine Kevin, Mah Dennis
ProCure Proton Therapy Center, Somerset, NJ, USA.
J Appl Clin Med Phys. 2018 Nov;19(6):53-59. doi: 10.1002/acm2.12436. Epub 2018 Aug 23.
This study evaluates the feasibility of lung dose prediction based on target contour and patient anatomy for breast patients treated with proton therapy.
Fifty-two randomly selected patients were included in the cohort, who were treated to 50.4-66.4 Gy(RBE) to the left (36), right (15), or bilateral (1) breast with uniform scanning (32) or pencil beam scanning (20). Anterior-oblique beams were used for each patient. The prescription doses were all scaled to 50.4 Gy(RBE) for the current analysis. Isotropic expansions of the planning target volume of various margins m were retrospectively generated and compared with isodose volumes in the ipsilateral lung. The fractional volume V of each expansion contour within the ipsilateral lung was compared with dose-volume data of clinical plans to establish the relationship between the margin m and dose D for the ipsilateral lung such that V = V(m). This relationship enables prediction of dose-volume V from V(m), which could be derived from contours before any plan is generated, providing a goal of plan quality. Lung V and V were considered for this pilot study, while the results could be generalized to other dose levels and/or other organs.
The actual V ranged from 6% to 23%. No statistically significant difference in V was found between breast irradiation and chest wall irradiation (P = 0.8) or between left-side and right-side treatment (P = 0.9). It was found that V(1.1 cm) predicted V to within 5% root-mean-square deviation (RMSD) and V(2.2 cm) predicted V to within 6% RMSD.
A contour-based model was established to predict dose to ipsilateral lung in breast treatment. Clinically relevant accuracy was demonstrated. This model facilitates dose prediction before treatment planning. It could serve as a guide toward realistic clinical goals in the planning stage.
本研究评估了基于靶区轮廓和患者解剖结构对接受质子治疗的乳腺癌患者进行肺部剂量预测的可行性。
该队列纳入了52例随机选择的患者，他们接受了50.4 - 66.4 Gy（相对生物效应）的左侧（36例）、右侧（15例）或双侧（1例）乳腺照射，采用均匀扫描（32例）或笔形束扫描（20例）。每位患者均使用前斜野。当前分析将处方剂量均缩放至50.4 Gy（相对生物效应）。回顾性生成了各种边界m的计划靶区体积的各向同性扩展，并与同侧肺内的等剂量体积进行比较。将同侧肺内每个扩展轮廓的分数体积V与临床计划的剂量 - 体积数据进行比较，以建立边界m与同侧肺剂量D之间的关系，即V = V(m)。这种关系能够从V(m)预测剂量 - 体积V，V(m)可从任何计划生成之前的轮廓得出，从而提供计划质量目标。本初步研究考虑了肺V 和V ，而结果可推广到其他剂量水平和/或其他器官。
实际V 范围为6%至23%。在乳腺照射和胸壁照射之间（P = 0.8）或左侧和右侧治疗之间（P = 0.9），未发现V 有统计学显著差异。发现V(1.1 cm)预测V 的均方根偏差（RMSD）在5%以内，V(2.2 cm)预测V 的RMSD在6%以内。
建立了基于轮廓的模型来预测乳腺癌治疗中同侧肺的剂量。证明了具有临床相关性的准确性。该模型有助于在治疗计划前进行剂量预测。它可作为规划阶段实现现实临床目标的指南。
