Tanaka Hidekazu, Hayashi Shinya, Kajiura Yuichi, Kitahara Masashi, Matsuyama Katsuya, Kanematsu Masayuki, Hoshi Hiroaki
Department of Radiology, Gifu University Graduate School of Medicine, Gifu, Japan ; Department of Radiology, Gifu University Hospital, Gifu, Japan.
Depertment of Radiation Oncology, Gifu Prefectural Tajimi Hospital, Tajimi, Japan.
Nagoya J Med Sci. 2015 Aug;77(3):339-45.
Several studies have reported the advantages of the field-in-field (FIF) technique in breast radiotherapy, including dose reduction in the lungs by using lung field blocks. We evaluated the FIF technique with lung blocks for breast tangential radiotherapy. Sixteen patients underwent free breathing (FB) computed tomography (CT), followed by two CT procedures performed during breath hold after light inhalation (IN) and light exhalation (EX). Three radiotherapy plans were created using the FIF technique based on the FB-CT images: one without lung blocks (LB0) and two with lung blocks whose monitor units (MUs) were 5 (LB5) and 10 (LB10), respectively. These plans were copied to the IN-CT and EX-CT images. V20Gy, V30Gy, and V40Gy of the ipsilateral lung and V100%, V95%, and the mean dose (Dmean) to the planning target volume (PTV) were analyzed. The extent of changes in these parameters on the IN-plan and EX-plan compared with the FB-plan was evaluated. V20Gy, V30Gy, and V40Gy were significantly smaller for FB-LB5 and FB-LB10 than for FB-LB0; similar results were obtained for the IN-plan and EX-plan. V100%, V95%, and Dmean were also significant smaller for FB-LB5 and FB-LB10 than for FB-LB0. The extent of changes in V20Gy, V30Gy, and V40Gy on the IN-plan and EX-plan compared with the FB-plan was not statistically significant. Lung blocks were useful for dose reduction in the lung and a simultaneous PTV decrease. This technique should not be applied in the general population.
多项研究报告了乳腺放射治疗中野中野（FIF）技术的优势，包括使用肺部野阻挡器可减少肺部剂量。我们评估了采用肺部阻挡器的FIF技术用于乳腺切线放射治疗的情况。16例患者先进行了自由呼吸（FB）计算机断层扫描（CT），随后在浅吸气（IN）和浅呼气（EX）后屏气时进行了两次CT检查。基于FB-CT图像使用FIF技术创建了三个放射治疗计划：一个不使用肺部阻挡器（LB0），两个使用肺部阻挡器，其监测单位（MU）分别为5（LB5）和10（LB10）。这些计划被复制到IN-CT和EX-CT图像上。分析了同侧肺的V20Gy、V30Gy和V40Gy以及计划靶体积（PTV）的V100%、V95%和平均剂量（Dmean）。评估了与FB计划相比，IN计划和EX计划中这些参数的变化程度。FB-LB5和FB-LB10的V20Gy、V30Gy和V40Gy明显小于FB-LB0；IN计划和EX计划也得到了类似结果。FB-LB5和FB-LB10的V100%、V95%和Dmean也明显小于FB-LB0。与FB计划相比，IN计划和EX计划中V20Gy、V30Gy和V40Gy的变化程度无统计学意义。肺部阻挡器有助于减少肺部剂量并同时降低PTV。该技术不应应用于普通人群。
