Department of Radiation Oncology, Peter MacCallum Cancer Centre, Melbourne, Australia.
Radiother Oncol. 2013 May;107(2):165-70. doi: 10.1016/j.radonc.2013.04.005. Epub 2013 May 3.
To compare the cone-beam CT (CBCT) soft tissue localization disparity between radiation oncologists (RO) and radiation therapy technologists (RTT) in a novel online protocol of image-guided adaptive radiotherapy to the postoperative prostate bed.
Using the planning CT and pre-treatment CBCTs from the first week of radiotherapy, four adaptive plans of different sizes were derived for each of eight post-prostatectomy patients. Four ROs collectively defined the reference answer, i.e. the plan of the day and isocentre correction for 40 CBCTs taken in weeks 2-6 of treatment for each patient. RTTs were randomly assigned five of these CBCTs; and asked to record their plan of the day selection and isocentre correction. RTT selection and reference answers were compared. The distance between the RTT selection and the reference answer was calculated.
A total of 33 RTTs took part in this study. The average difference in CTV volume (reference answer-RTT selection) was 1.32 cm(3) (SD 29 cm(3)) overall. The average difference between reference answer and RTT isocentre coordinates was SI 1mm (SD 4.8mm), LR 1.1mm (SD 4.0mm) and AP -0.2mm (SD 3.9 mm). Distance of superior 8mm, inferior 6mm, left 4mm, right 2mm, anterior 6mm and posterior 6mm covered 100% of the CTV in 90% of fractions.
The difference between RTT and RO selection of adaptive volumes is small and can be accounted for in a clinically acceptable CTV to PTV margin. Adaptive post-prostatectomy radiotherapy is feasible, in the setting of an academic center although at the moment, we have insufficient evidence to suggest that margins can yet be reduced with IGART with the current protocol.
比较在线图像引导自适应放疗新技术中，肿瘤放射治疗医师（RO）和放射治疗技师（RTT）在勾画前列腺术后床体靶区的锥形束 CT（CBCT）软组织定位差异。
利用 8 例前列腺癌术后患者的计划 CT 和治疗开始后第一周的治疗前 CBCT，分别为每位患者生成 4 个不同大小的自适应计划。4 名 RO 共同确定参考答案，即每位患者治疗第 2-6 周 40 次 CBCT 中的当日计划和等中心校正。将这 40 次 CBCT 中的 5 次随机分配给 RTT，要求他们记录当日计划选择和等中心校正。比较 RTT 选择和参考答案的差异，计算 RTT 选择与参考答案之间的距离。
共有 33 名 RTT 参与了本研究。CTV 体积（参考答案-RTT 选择）的平均差异为 1.32cm3（SD 29cm3）。参考答案和 RTT 等中心坐标的平均差异分别为 SI 1mm（SD 4.8mm）、LR 1.1mm（SD 4.0mm）和 AP -0.2mm（SD 3.9mm）。上、下、左、右、前、后各 8mm、6mm、4mm、2mm、6mm 和 6mm 的距离覆盖了 90%的分次中 100%的 CTV。
RTT 和 RO 对自适应靶区体积的选择差异较小，且可以在临床可接受的 CTV 到 PTV 边界中得到解释。尽管目前我们没有足够的证据表明可以根据当前方案通过 IGART 进一步减少边缘，但在学术中心开展前列腺癌术后自适应放疗是可行的。
