Lee Joo Hwan, Lee Dong Soo, Park So Hyun, Lee Young Kyu, Kim Jeong Soo, Kim Yong Seok
1 Department of Radiation Oncology, College of Medicine, The Catholic University of Korea, Uijeongbu, South Korea.
2 Department of General Surgery, College of Medicine, The Catholic University of Korea, Seoul, South Korea.
Tumour Biol. 2018 Aug;40(8):1010428318791882. doi: 10.1177/1010428318791882.
The aim of this study was to assess tissue computed tomography (CT) number changes and corresponding dosimetric shifts in repeatedly performed simulation CT (re-sim CT) scans after conventionally fractionated irradiation in breast cancer patients. A total of 28 breast cancer patients who underwent breast-conserving surgery were enrolled in this study. All the patients had received 50.4 Gy of conventional whole-breast irradiation (WBI) and underwent re-sim CT scans for tumor bed boost. For evaluation of dosimetric shifts between initial and re-sim CT scans, electron boost plans in the same field size with the same monitor unit with source-to-skin distance of 100 cm were conducted. Dosimetric parameters (V, V, V, V, V, V: V indicates volumes which receive X% of prescribed doses) between initial and re-sim CT scans were compared. The CT number data (CT, CT, CT) of the original and irradiated CT (re-sim CT) scans from each representative structure (lung, rib bone, soft tissue, muscle, etc.) were examined and recruited. CT numbers showed highly variable changes. Soft tissue CT and muscle CT/CT showed statistically and significantly increased values in the CT (re-sim CT) compared to the original CT scans. Rib bone CT/CT showed statistically and significantly decreased values in the re-sim CT compared to the original CT scans. Other CT number values showed no statistically significant changes. Among the dosimetric parameters, only V (p = 0.015, mean = 3.07 cc versus 1.63 cc) and V (p = 0.017, mean = 13.8 cc versus 11.9 cc) exhibited statistically increased values in the re-sim CT compared to the original CT scans. CT number changes after conventional WBI were different according to tissue component. For electron boost plans, the implementation of a re-sim CT might be helpfully considered because significant dosimetric factor changes were observed especially in the high-dose areas (hot spots: V and V).
本研究的目的是评估乳腺癌患者在常规分割放疗后重复进行的模拟CT（重新模拟CT）扫描中组织计算机断层扫描（CT）值的变化以及相应的剂量学偏移。本研究共纳入28例接受保乳手术的乳腺癌患者。所有患者均接受了50.4 Gy的常规全乳照射（WBI），并进行了肿瘤床加量的重新模拟CT扫描。为评估初始CT扫描和重新模拟CT扫描之间的剂量学偏移，在相同野大小、相同监测单位且源皮距为100 cm的条件下制定了电子加量计划。比较了初始CT扫描和重新模拟CT扫描之间的剂量学参数（V、V、V、V、V、V：V表示接受X%处方剂量的体积）。检查并收集了每个代表性结构（肺、肋骨、软组织、肌肉等）的原始CT扫描和照射后CT（重新模拟CT）扫描的CT值数据（CT、CT、CT）。CT值显示出高度可变的变化。与原始CT扫描相比，软组织CT以及肌肉CT/CT在重新模拟CT扫描中显示出统计学上显著增加的值。与原始CT扫描相比，肋骨CT/CT在重新模拟CT扫描中显示出统计学上显著降低的值。其他CT值未显示出统计学上的显著变化。在剂量学参数中，与原始CT扫描相比，只有V（p = 0.015，平均值 = 3.07 cc对1.63 cc）和V（p = 0.017，平均值 = 13.8 cc对11.9 cc）在重新模拟CT扫描中显示出统计学上增加的值。常规WBI后的CT值变化因组织成分而异。对于电子加量计划，可能有必要考虑进行重新模拟CT扫描，因为观察到尤其是在高剂量区域（热点：V和V）出现了显著的剂量学因素变化。
