Radiation Oncology Division, Peter MacCallum Cancer Centre, Locked Bag 1, A'Beckett Street, East Melbourne, VIC, 8006, Australia.
Radiat Oncol. 2012 Aug 13;7:139. doi: 10.1186/1748-717X-7-139.
To analyze interfraction motion of seminal vesicles (SV), and its motion relative to rectal and bladder filling.
SV and prostate were contoured on 771 daily computed tomography "on rails" scans from 24 prostate cancer patients undergoing radiotherapy. Random and systematic errors for SV centroid displacement were measured relative to the prostate centroid. Margins required for complete geometric coverage of SV were determined using isotropic expansion of reference contours. SV motion relative to rectum and bladder was determined.
Systematic error for the SV was 1.9 mm left-right (LR), 2.9 mm anterior-posterior (AP) and 3.6 mm superior-inferior (SI). Random error was 1.4 mm (LR), 2.7 mm (AP) and 2.1 mm (SI). 10 mm margins covered the entire left SV and right SV on at least 90% of fractions in 50% and 33% of patients and 15 mm margins covered 88% and 79% respectively. SV AP movement correlated with movement of the most posterior point of the bladder (mean R2 = 0.46, SD = 0.24) and rectal area (mean R2 = 0.38, SD = 0.21).
Considerable interfraction displacement of SV was observed in this cohort of patients. Bladder and rectal parameters correlated with SV movement.
分析精囊（SV）的分次运动及其与直肠和膀胱充盈的相对运动。
对 24 名接受放疗的前列腺癌患者的 771 次每日 CT“轨道”扫描中的 SV 和前列腺进行轮廓勾画。测量 SV 质心位移的随机和系统误差相对于前列腺质心。使用参考轮廓的各向同性膨胀确定完全覆盖 SV 的几何形状所需的边界。确定 SV 相对于直肠和膀胱的运动。
SV 的系统误差为 1.9mm 左右（LR）、2.9mm 前后（AP）和 3.6mm 上下（SI）。随机误差为 1.4mm（LR）、2.7mm（AP）和 2.1mm（SI）。在 50%和 33%的患者中，至少 90%的分次中，10mm 的边界可以覆盖整个左 SV 和右 SV，而 15mm 的边界分别可以覆盖 88%和 79%。SV 的 AP 运动与膀胱最后端点的运动（平均 R2=0.46，SD=0.24）和直肠面积（平均 R2=0.38，SD=0.21）相关。
在本队列患者中观察到相当大的 SV 分次间位移。膀胱和直肠参数与 SV 运动相关。
