Ko Heejoo, Chang Jee Suk, Moon Jin Young, Lee Won Hee, Shah Chirag, Shim Jin Sup Andy, Han Min Cheol, Baek Jong Geol, Park Ryeong Hwang, Kim Yong Bae, Kim Jin Sung
College of Medicine, The Catholic University of Korea, Seoul, South Korea.
Department of Radiation Oncology, Yonsei Cancer Center, Yonsei University College of Medicine, Seoul, South Korea.
Front Oncol. 2021 Apr 12;11:645328. doi: 10.3389/fonc.2021.645328. eCollection 2021.
How modern cardiac sparing techniques and beam delivery systems using advanced x-ray and proton beam therapy (PBT) can reduce incidental radiation exposure doses to cardiac and pulmonary organs individually or in any combination is poorly investigated.
Among 15 patients with left-sided breast cancer, partial wide tangential 3D-conformal radiotherapy (3DCRT) delivered in conventional fractionation (CF) or hypofractionated (HF) schedules; PBT delivered in a CF schedule; and volumetric modulated arc therapy (VMAT) delivered in an HF schedule, each under continuous positive airway pressure (CPAP) and free-breathing (FB) conditions, were examined. Target volume coverage and doses to organs-at-risk (OARs) were calculated for each technique. Outcomes were compared with one-way analysis of variance and the Bonferroni test, with -values <0.05 considered significant.
Target volume coverage was within acceptable levels in all interventions, except for the internal mammary lymph node D95 (99% in PBT, 90% in VMAT-CPAP, 84% in VMAT-FB, and 74% in 3DCRT). The mean heart dose (MHD) was the lowest in PBT (<1 Gy) and VMAT-CPAP (2.2 Gy) and the highest in 3DCRT with CF/FB (7.8 Gy), respectively. The mean lung dose (MLD) was the highest in 3DCRT-CF-FB (20 Gy) and the lowest in both VMAT-HF-CPAP and PBT (approximately 5-6 Gy). VMAT-HF-CPAP and PBT delivered a comparable maximum dose to the left ascending artery (7.2 and 6.13 Gy, respectively).
Both proton and VMAT in combination with CPAP can minimize the radiation exposure to heart and lung with optimal target coverage in regional RT for left-sided breast cancer. The clinical relevance of these differences is yet to be elucidated. Continued efforts are needed to minimize radiation exposures during RT treatment to maximize its therapeutic index.
现代心脏保护技术以及使用先进X射线和质子束疗法（PBT）的射束传输系统如何单独或通过任何组合降低心脏和肺部器官的附带辐射暴露剂量，这方面的研究较少。
在15例左侧乳腺癌患者中，分别检查了常规分割（CF）或大分割（HF）方案下的部分宽切线三维适形放疗（3DCRT）；CF方案下的PBT；以及HF方案下的容积调强弧形放疗（VMAT），每种治疗均在持续气道正压通气（CPAP）和自由呼吸（FB）条件下进行。计算每种技术的靶区覆盖范围和危及器官（OARs）的剂量。结果采用单因素方差分析和Bonferroni检验进行比较，P值<0.05被认为具有统计学意义。
除内乳淋巴结D95外（PBT中为99%，VMAT-CPAP中为90%，VMAT-FB中为84%，3DCRT中为74%），所有干预措施的靶区覆盖范围均在可接受水平内。平均心脏剂量（MHD）在PBT（<1 Gy）和VMAT-CPAP（2.2 Gy）中最低，在CF/FB的3DCRT中最高（7.8 Gy）。平均肺剂量（MLD）在3DCRT-CF-FB中最高（20 Gy），在VMAT-HF-CPAP和PBT中最低（约5-6 Gy）。VMAT-HF-CPAP和PBT对左升动脉的最大剂量相当（分别为7.2和6.13 Gy）。
质子束疗法和VMAT联合CPAP可在左侧乳腺癌的区域放疗中，以最佳靶区覆盖将心脏和肺部的辐射暴露降至最低。这些差异的临床相关性尚待阐明。需要继续努力将放疗期间的辐射暴露降至最低，以最大化其治疗指数。
