基于放疗中重复四维CT的食管癌大体肿瘤体积与位移的相关性

目的 基于放疗中重复4DCT增强扫描探讨胸段食管癌原发肿瘤分次放疗内大体肿瘤体积大小、长度及最大橫径与位移的相关性。方法 32例胸段食管癌患者分别于放疗前及10、20、30次时行4DCT模拟定位增强扫描,获取各次4DCT扫描GTV三维方向位移并分析其与体积、长度及最大横径的相关性。结果 放疗20次时,全部患者、胸下段癌患者肿瘤体积与左右方向位移呈正相关(P=0.012、0.040),全部患者、胸上、中段癌患者肿瘤长度与GTV上下方向位移呈正相关(P=0.003、0.031、0.044),胸下段癌患者肿瘤长度与GTV左右方向位移呈正相关(P=0.027)。初次扫描全部患者最大橫径与GTV左右方向、上下方向、三维运动矢量均呈正相关(P=0.036、0.033、0.018),胸下段癌患者最大橫径仅与GTV左右方向位移相关(P=0.011)。结论 放疗中各时段各部位食管癌体积、长度及最大横径与GTV前后方向位移均无相关性,而在左右、上下方向的相关性则依病变部位及疗程时段不同而异。

Correlation between displacement of GTV and volumetric parameters of primary tumor in thoracic esophageal cancer based on repeated 4DCT scans during radiotherapy

Objective To investigate the correlation between the displacement of gross tumor volume (GTV) and the volume, length, and largest diameter of primary tumor in thoracic esophageal cancer based on repeated enhanced four-dimensional computed tomography (4DCT) scans during fractionated radiotherapy. Methods Thirty enrolled patients with thoracic esophageal cancer underwent enhanced 4DCT scans before radiotherapy and every ten fractions during radiotherapy. The displacements of GTV in left-right (LR), anterior-posterior (AP), and superior-inferior (SI) directions in each scan were obtained, and then the correlation between the displacements and the volume, length, and largest diameter of primary tumor was analyzed. Results In the 20^th fraction, a significant positive correlation was observed between the displacement of GTV in LR direction and the volume of primary tumor for all patients and the patients with lower-thoracic esophageal cancer (P=0.012 and 0.040), between the displacement of GTV in SI direction and the length of primary tumor for all patients and the patients with upper-and middle-thoracic esophageal cancer (P=0.003, 0.031, and 0.044), and between the displacement of GTV in LR direction and the length of primary tumor for the patients with lower-thoracic esophageal cancer (P=0.027). At the first 4DCT scan before radiotherapy, a significant positive correlation was observed between the largest diameter of primary tumor and the displacement of GTV in LR and SI directions and three-dimensional vector for all patients (P=0.036, 0.033, and 0.018) and between the largest diameter of primary tumor and the displacement of GTV in LR direction for the patients with lower-thoracic esophageal cancer (P=0.011). Conclusions In different fractions of radiotherapy, no significant correlation is found between the displacement of GTV in AP direction and the volume, length, and largest diameter of primary tumor in patients with lower-, middle-, or upper-thoracic esophageal cancer. However, their correlation with the displacement of GTV in LR and SI directions depends on the location of tumor and fraction of radiotherapy.