Department of Radiation Oncology, Northern Sydney Cancer Centre, Royal North Shore Hospital, St Leonards, NSW, Australia.
Northern Clinical School, University of Sydney, Sydney, NSW, Australia.
J Med Radiat Sci. 2022 Mar;69(1):75-84. doi: 10.1002/jmrs.473. Epub 2021 May 6.
Until late 2018, standard of practice at the Northern Sydney Cancer Centre (NSCC) for breast and nodal treatment was a conformal mono-isocentric technique. A planning study comparing an existing mono-isocentric three-dimensional conformal radiotherapy (3D-CRT) planning technique to a hybrid intensity-modulated radiotherapy (hIMRT) approach for the whole breast and supraclavicular fossa (SCF) region was undertaken with the aim to improve plan quality by improving dose conformity/homogeneity across target volumes and reducing hotspots outside the target.
A cohort of 17 patients was retrospectively planned using the proposed hIMRT technique, keeping the same planning constraints as the original treated breast and SCF 3D-CRT plan and normalising the 3D-CRT plans to achieve minimum breast/SCF target coverage to compare organs at risk (OARs). Normal tissue index (NTI) and homogeneity index (HI) were compared for plan quality as well as for evaluating OARs.
The hIMRT technique showed statistically significant improvements in NTI and HI, as well as improvement in maximum brachial plexus and thyroid doses. There was a negligible increase in maximum oesophagus dose which could be improved if used in optimisation. Other OAR doses in the irradiated region were comparable to the 3D-CRT plans, however maximum doses were reduced overall.
The hIMRT planning technique maintained clinically acceptable doses to OARs and reduced normal tissue dose while maintaining equivalent dose coverage to breast and SCF planning target volumes with improved conformity and homogeneity. The reduction in maximum doses promotes a favourable toxicity profile, with potential benefit of improved long-term cosmesis.
直到 2018 年末，北悉尼癌症中心（NSCC）的乳房和淋巴结治疗标准实践都是一种适形单中心技术。我们进行了一项规划研究，比较了现有的单中心三维适形放疗（3D-CRT）规划技术与全乳房和锁骨上窝（SCF）区域的混合调强放疗（hIMRT）方法，旨在通过改善靶区体积的剂量一致性/均匀性并减少靶区外热点来提高计划质量。
回顾性地为 17 例患者使用拟议的 hIMRT 技术进行规划，保留与原始治疗乳房和 SCF 3D-CRT 计划相同的规划约束，并对 3D-CRT 计划进行归一化，以确保最小的乳房/SCF 靶区覆盖率，从而比较危及器官（OAR）。比较了计划质量的正常组织指数（NTI）和均匀性指数（HI），以及评估 OARs。
hIMRT 技术在 NTI 和 HI 方面均显示出统计学显著改善，同时臂丛神经和甲状腺的最大剂量也得到了改善。食管最大剂量略有增加，如果在优化中使用，可能会得到改善。照射区域的其他 OAR 剂量与 3D-CRT 计划相当，但总体最大剂量降低。
hIMRT 规划技术在保持 OAR 临床可接受剂量的同时降低了正常组织剂量，同时保持了对乳房和 SCF 计划靶区的等效剂量覆盖，提高了适形性和均匀性。最大剂量的降低促进了有利的毒性特征，可能改善长期美容效果。
