Medical Physics Department, Prof. Franciszek Łukaszczyk Memorial Oncology Center, Bydgoszcz, Poland.
Clinic of Oncology and Brachytherapy, Collegium Medicum in Bydgoszcz, Nicholas Copernicus University, Torun, Poland.
Acta Oncol. 2023 Aug;62(8):932-941. doi: 10.1080/0284186X.2023.2238553. Epub 2023 Jul 30.
The purpose of this study was to evaluate three techniques of irradiation of left-sided breast cancer patients, three-dimensional conformal radiotherapy (3D-CRT), hybrid Intensity-Modulated Radiotherapy (h-IMRT), and hybrid Volumetric-Modulated Arc Therapy (h-VMAT, h-ARC), in terms of dose distribution in the planning target volume (PTV) and organs at risk (OARs). The second aim was to estimate the projected relative risk of radiation-induced secondary cancers for hybrid techniques.
Three treatment plans were prepared in 3D-CRT, h-IMRT, and h-VMAT techniques for each of the 40 patients, who underwent CT simulation in deep inspiration breath-hold (DIBH). For hybrid techniques, plans were created by combining 3D-CRT and dynamic fields with an 80%/20% dose ratio for 3D-CRT and IMRT or VMAT. Cumulative dose-volume histograms were used to compare dose distributions within the PTV and OARs (heart, left anterior descending coronary artery [LAD], left and right lung [LL, RL], right breast [RB]). Projected risk ratios for secondary cancers were estimated relative to 3D-CRT using the organ equivalent dose (OED) concept for the Schneider's linear exponential, plateau, and full mechanistic dose-response model.
All plans fulfilled the PTV criterium: V95%≥95%. Compared to 3D-CRT, both hybrid techniques showed significantly better target coverage (PTV: V95%>98%, < 0.001), and the best conformality was achieved by h-ARC plans (CI: 1.18 ± 0.09, < 0.001). Compared to 3D-CRT and h-ARC, h-IMRT increased the average sum of monitor units (MU) over 129.9% ( < 0.001). H-ARC increased the mean dose of contralateral organs and the LL V5Gy parameter ( < 0.001). Both hybrid techniques significantly reduced the of the heart by 5 Gy. Compared to h-IMRT, h-ARC increased secondary cancer projected relative risk ratios for LL, RL, and RB by 18, 152, and 81%, respectively.
The results confirmed that both hybrid techniques provide better target quality and OARs sparing than 3D-CRT. Hybrid VMAT delivers less MU compared to hybrid IMRT but may increase the risk of radiation-induced secondary malignancies.
本研究旨在评估三种左侧乳腺癌患者放疗技术，即三维适形放疗（3D-CRT）、混合调强放疗（h-IMRT）和混合容积调强弧形放疗（h-VMAT，h-ARC），在计划靶区（PTV）和危及器官（OARs）的剂量分布方面的差异。本研究的第二个目的是估计混合技术导致二次癌症的相对风险。
对 40 名接受深吸气屏气（DIBH）CT 模拟的患者，在 3D-CRT、h-IMRT 和 h-VMAT 技术中分别为每位患者制定了三种治疗计划。对于混合技术，通过将 3D-CRT 和动态野相结合，并将 3D-CRT 和调强放疗或调强弧形放疗的剂量比设定为 80%/20%，来创建计划。使用累积剂量-体积直方图比较 PTV 和 OARs（心脏、左前降支冠状动脉[LAD]、左肺[LL]和右肺[RL]、右乳[RB]）内的剂量分布。使用器官当量剂量（OED）概念，基于施耐德的线性指数、平台和全机制剂量反应模型，对二次癌症的风险比相对于 3D-CRT 进行估计。
所有计划均满足 PTV 标准：V95%≥95%。与 3D-CRT 相比，两种混合技术均显著提高了靶区覆盖率（PTV：V95%>98%，<0.001），h-ARC 计划具有最佳的适形性（CI：1.18±0.09，<0.001）。与 3D-CRT 和 h-ARC 相比，h-IMRT 使平均监测单位（MU）增加了 129.9%（<0.001）。h-ARC 增加了对侧器官的平均剂量和 LL V5Gy 参数（<0.001）。两种混合技术均显著降低了心脏的 5Gy 剂量。与 h-IMRT 相比，h-ARC 使 LL、RL 和 RB 的二次癌症预计相对风险比分别增加了 18%、152%和 81%。
结果证实，两种混合技术均比 3D-CRT 提供更好的靶区质量和 OAR 保护。与混合调强放疗相比，混合调强弧形放疗的 MU 用量较少，但可能会增加放射诱导继发性恶性肿瘤的风险。
