Onal Cem, Cengiz Mustafa, Guler Ozan C, Dolek Yemliha, Ozkok Serdar
1 Department of Radiation Oncology, Faculty of Medicine, Baskent University, Adana, Turkey.
2 Department of Radiation Oncology, Faculty of Medicine, Hacettepe University, Ankara, Turkey.
Br J Radiol. 2017 May;90(1073):20160826. doi: 10.1259/bjr.20160826. Epub 2017 Mar 24.
To assess whether delineation courses for radiation oncologists improve interobserver variability in target volume delineation for post-operative gastric cancer radiotherapy planning.
29 radiation oncologists delineated target volumes in a gastric cancer patient. An experienced radiation oncologist lectured about delineation based on contouring atlas and delineation recommendations. After the course, the radiation oncologists, blinded to the previous delineation, provided delineation for the same patient.
The difference between delineated volumes and reference volumes for pre- and post-course clinical target volume (CTV) were 19.8% (-42.4 to 70.6%) and 12.3% (-12.0 to 27.3%) (p = 0.26), respectively. The planning target volume (PTV) differences pre- and post-course according to the reference volume were 20.5% (-40.7 to 93.7%) and 13.1% (-10.6 to 29.5%) (p = 0.30), respectively. The concordance volumes between the pre- and post-course CTVs and PTVs were 467.1 ± 89.2 vs 597.7 ± 54.6 cm (p < 0.001) and 738.6 ± 135.1 vs 893.2 ± 144.6 cm (p < 0.001), respectively. Minimum and maximum observer variations were seen at the cranial part and splenic hilus and at the caudal part of the CTV. The kappa indices compared with the reference contouring at pre- and post-course delineations were 0.68 and 0.82, respectively.
The delineation course improved interobserver variability for gastric cancer. However, impact of target volume changes on toxicity and local control should be evaluated for further studies. Advances in knowledge: This study demonstrated that a delineation course based on current recommendations helped physicians delineate smaller and more homogeneous target volumes. Better target volume delineation allows proper target volume irradiation and preventing unnecessary normal tissue irradiation.
评估放射肿瘤学家的靶区勾画课程是否能改善术后胃癌放疗计划中靶区体积勾画的观察者间变异性。
29名放射肿瘤学家对一名胃癌患者的靶区体积进行了勾画。一位经验丰富的放射肿瘤学家基于轮廓图谱和勾画建议进行了关于靶区勾画的讲座。课程结束后，这些放射肿瘤学家在不知道之前勾画结果的情况下，再次为同一名患者进行靶区勾画。
课程前后临床靶区体积（CTV）的勾画体积与参考体积之间的差异分别为19.8%（-42.4%至70.6%）和12.3%（-12.0%至27.3%）（p = 0.26）。根据参考体积，课程前后计划靶区体积（PTV）的差异分别为20.5%（-40.7%至93.7%）和13.1%（-10.6%至29.5%）（p = 0.30）。课程前后CTV和PTV的一致性体积分别为467.1±89.2 vs 597.7±54.6 cm（p < 0.001）和738.6±135.1 vs 893.2±144.6 cm（p < 0.001）。观察者间最小和最大变异分别出现在CTV的头端部分和脾门以及尾端部分。课程前后与参考轮廓相比的kappa指数分别为0.68和0.82。
靶区勾画课程改善了胃癌的观察者间变异性。然而，靶区体积变化对毒性和局部控制的影响应在进一步研究中进行评估。知识进展：本研究表明，基于当前建议的靶区勾画课程有助于医生勾画出更小且更均匀的靶区体积。更好的靶区体积勾画可实现对靶区体积的适当照射并防止不必要的正常组织照射。
