Medical Physics Department, Veneto Institute of Oncology IOV - IRCCS, Padua, Italy.
Medical Physics Department, Veneto Institute of Oncology IOV - IRCCS, Padua, Italy.
Phys Med. 2022 Sep;101:44-49. doi: 10.1016/j.ejmp.2022.07.007. Epub 2022 Aug 6.
Breast cancer is the most frequently diagnosed tumor in pregnant women and radiation therapy should carefully be weighted up because of the dose to the fetus. The aim of this study was to investigate fetal dose in a patient treated with Virtual Tangential-fields Arc Therapy (ViTAT), an innovative technique for whole breast irradiation. Optically stimulated luminescence detectors (OSLDs) were calibrated on a Varian TrueBeam linac, with both a 6X and 6XFFF beam quality, and used for out-of-field measurements. Fetal dose related with ViTAT technique was compared to the standard 3D conformal radiation therapy technique (3DCRT). The fetal dose delivered with a ViTAT technique planned with 6XFFF beam was also investigated. Measurements were taken on a phantom composed of Rando Alderson Phantom slices and solid water slabs. OSLDs were placed in a region identified by the height of the fundus from conception to the twentieth week using a custom made PMMA grid. Due to the higher number of monitor units, the peripheral dose of ViTAT delivered with 6X beams is higher than that of 3DCRT. However, nanoDots measurements prove that ViTAT can be used in place of 3DCRT while maintaining similar fetal dose levels if 6XFFF beams are used.
乳腺癌是孕妇中最常见的肿瘤，由于胎儿剂量的原因，放射治疗应仔细权衡。本研究的目的是研究使用虚拟切线弧形治疗（VitAT）治疗的患者的胎儿剂量，这是一种用于全乳房照射的创新技术。光激励发光探测器（OSLD）在瓦里安 TrueBeam 直线加速器上进行校准，使用 6X 和 6XFFF 两种射线质量，并用于场外测量。比较了 VitAT 技术与标准 3D 适形放射治疗技术（3DCRT）的胎儿剂量。还研究了使用 6XFFF 射线计划的 VitAT 技术所产生的胎儿剂量。测量是在由 Rando Alderson 体模切片和固体水平板组成的体模上进行的。OSLD 放置在一个通过从受孕到第 20 周的底壁高度确定的区域中，使用定制的 PMMA 网格。由于监测单位数量较多，使用 6X 射线的 VitAT 外周剂量高于 3DCRT。但是，nanoDot 测量证明，如果使用 6XFFF 射线，可以使用 VitAT 代替 3DCRT，同时保持相似的胎儿剂量水平。
