Roberge D, Skamene T, Turcotte R E, Powell T, Saran N, Freeman C
Division of Radiation Oncology, McGill University Health Centre, 1650 Cedar Avenue, Montreal, Canada.
Cancer Radiother. 2011 Aug;15(5):421-5. doi: 10.1016/j.canrad.2011.03.006. Epub 2011 Jul 8.
To evaluate inter- and intra-observer variability in gross tumor volume definition for adult limb/trunk soft tissue sarcomas.
Imaging studies of 15 patients previously treated with preoperative radiation were used in this study. Five physicians (radiation oncologists, orthopedic surgeons and a musculoskeletal radiologist) were asked to contour each of the 15 tumors on T1-weighted, gadolinium-enhanced magnetic resonance images. These contours were drawn twice by each physician. The volume and center of mass coordinates for each gross tumor volume were extracted and a Boolean analysis was performed to measure the degree of volume overlap.
The median standard deviation in gross tumor volumes across observers was 6.1% of the average volume (range: 1.8%-24.9%). There was remarkably little variation in the 3D position of the gross tumor volume center of mass. For the 15 patients, the standard deviation of the 3D distance between centers of mass ranged from 0.06 mm to 1.7 mm (median 0.1mm). Boolean analysis demonstrated that 53% to 90% of the gross tumor volume was common to all observers (median overlap: 79%). The standard deviation in gross tumor volumes on repeat contouring was 4.8% (range: 0.1-14.4%) with a standard deviation change in the position of the center of mass of 0.4mm (range: 0mm-2.6mm) and a median overlap of 93% (range: 73%-98%).
Although significant inter-observer differences were seen in gross tumor volume definition of adult soft-tissue sarcoma, the center of mass of these volumes was remarkably consistent. Variations in volume definition did not correlate with tumor size. Radiation oncologists should not hesitate to review their contours with a colleague (surgeon, radiologist or fellow radiation oncologist) to ensure that they are not outliers in sarcoma gross tumor volume definition. Protocols should take into account variations in volume definition when considering tighter clinical target volumes.
评估成人肢体/躯干软组织肉瘤大体肿瘤体积定义中的观察者间和观察者内变异性。
本研究使用了15例先前接受术前放疗患者的影像学研究资料。邀请了5位医生（放射肿瘤学家、骨科医生和一位肌肉骨骼放射科医生）在T1加权、钆增强磁共振图像上勾勒出15个肿瘤中的每一个。每位医生对这些轮廓进行了两次绘制。提取每个大体肿瘤体积的体积和质心坐标，并进行布尔分析以测量体积重叠程度。
观察者间大体肿瘤体积的中位标准差为平均体积的6.1%（范围：1.8%-24.9%）。大体肿瘤体积质心的三维位置变化非常小。对于这15例患者，质心之间三维距离的标准差范围为0.06毫米至1.7毫米（中位值0.1毫米）。布尔分析表明，所有观察者的大体肿瘤体积中有53%至90%是相同的（中位重叠率：79%）。重复勾勒时大体肿瘤体积的标准差为4.8%（范围：0.1%-14.4%），质心位置的标准差变化为0.4毫米（范围：0毫米至2.6毫米），中位重叠率为93%（范围：73%-98%）。
尽管在成人软组织肉瘤的大体肿瘤体积定义中观察到观察者间存在显著差异，但这些体积的质心非常一致。体积定义的变化与肿瘤大小无关。放射肿瘤学家应毫不犹豫地与同事（外科医生、放射科医生或放射肿瘤学同行）复查他们勾勒的轮廓，以确保在肉瘤大体肿瘤体积定义中他们不是异常值。在考虑更精确的临床靶体积时，方案应考虑体积定义的变化。
