Department of Clinical Oncology, Norfolk and Norwich University Hospital, Norwich, UK.
Br J Radiol. 2012 Aug;85(1016):1070-7. doi: 10.1259/bjr/32038456.
This study evaluates the interobserver variation in parotid gland delineation and its impact on intensity-modulated radiotherapy (IMRT) solutions.
The CT volumetric data sets of 10 patients with oropharyngeal squamous cell carcinoma who had been treated with parotid-sparing IMRT were used. Four radiation oncologists and three radiologists delineated the parotid gland that had been spared using IMRT. The dose-volume histogram (DVH) for each study contour was calculated using the IMRT plan actually delivered for that patient. This was compared with the original DVH obtained when the plan was used clinically.
70 study contours were analysed. The mean parotid dose achieved during the actual treatment was within 10% of 24 Gy for all cases. Using the study contours, the mean parotid dose obtained was within 10% of 24 Gy for only 53% of volumes by radiation oncologists and 55% of volumes by radiologists. The parotid DVHs of 46% of the study contours were sufficiently different from those used clinically, such that a different IMRT plan would have been produced.
Interobserver variation in parotid gland delineation is significant. Further studies are required to determine ways of improving the interobserver consistency in parotid gland definition.
本研究评估了腮腺勾画的观察者间变异性及其对调强放疗（IMRT）方案的影响。
使用了 10 例接受腮腺保护调强放疗的口咽鳞癌患者的 CT 容积数据集。4 位放射肿瘤学家和 3 位放射科医生使用 IMRT 勾画了被保护的腮腺。使用为每位患者实际提供的 IMRT 计划计算每个研究轮廓的剂量-体积直方图（DVH）。将其与计划在临床上使用时获得的原始 DVH 进行比较。
分析了 70 个研究轮廓。在所有情况下，实际治疗过程中获得的平均腮腺剂量均在 24Gy 的 10%以内。使用研究轮廓，只有 53%的放射肿瘤学家和 55%的放射科医生的腮腺体积获得的平均腮腺剂量在 24Gy 的 10%以内。46%的研究轮廓的腮腺 DVH 与临床上使用的 DVH 有足够大的差异，以至于会产生不同的 IMRT 计划。
腮腺勾画的观察者间变异性是显著的。需要进一步研究以确定如何提高腮腺定义的观察者间一致性。
