van Schie Marcel A, Steenbergen Peter, Dinh Cuong Viet, Ghobadi Ghazaleh, van Houdt Petra J, Pos Floris J, Heijmink Stijn W T J P, van der Poel Henk G, Renisch Steffen, Vik Torbjørn, van der Heide Uulke A
Department of Radiation Oncology, The Netherlands Cancer Institute, Amsterdam, The Netherlands.
Phys Med Biol. 2017 Jun 14;62(14):5575-5588. doi: 10.1088/1361-6560/aa75b8.
Dose painting by numbers (DPBN) refers to a voxel-wise prescription of radiation dose modelled from functional image characteristics, in contrast to dose painting by contours which requires delineations to define the target for dose escalation. The direct relation between functional imaging characteristics and DPBN implies that random variations in images may propagate into the dose distribution. The stability of MR-only prostate cancer treatment planning based on DPBN with respect to these variations is as yet unknown. We conducted a test-retest study to investigate the stability of DPBN for prostate cancer in a semi-automated MR-only treatment planning workflow. Twelve patients received a multiparametric MRI on two separate days prior to prostatectomy. The tumor probability (TP) within the prostate was derived from image features with a logistic regression model. Dose mapping functions were applied to acquire a DPBN prescription map that served to generate an intensity modulated radiation therapy (IMRT) treatment plan. Dose calculations were done on a pseudo-CT derived from the MRI. The TP and DPBN map and the IMRT dose distribution were compared between both MRI sessions, using the intraclass correlation coefficient (ICC) to quantify repeatability of the planning pipeline. The quality of each treatment plan was measured with a quality factor (QF). Median ICC values for the TP and DPBN map and the IMRT dose distribution were 0.82, 0.82 and 0.88, respectively, for linear dose mapping and 0.82, 0.84 and 0.94 for square root dose mapping. A median QF of 3.4% was found among all treatment plans. We demonstrated the stability of DPBN radiotherapy treatment planning in prostate cancer, with excellent overall repeatability and acceptable treatment plan quality. Using validated tumor probability modelling and simple dose mapping techniques it was shown that despite day-to-day variations in imaging data still consistent treatment plans were obtained.
数字式剂量描绘（DPBN）是指根据功能图像特征进行的体素级辐射剂量处方，这与基于轮廓的剂量描绘不同，后者需要通过勾画轮廓来定义剂量递增的靶区。功能成像特征与DPBN之间的直接关系意味着图像中的随机变化可能会传播到剂量分布中。基于DPBN的仅使用磁共振成像（MR）的前列腺癌治疗计划相对于这些变化的稳定性尚不清楚。我们进行了一项重测研究，以在仅使用MR的半自动治疗计划工作流程中研究DPBN用于前列腺癌的稳定性。12例患者在前列腺切除术前的两天分别接受了多参数MRI检查。前列腺内的肿瘤概率（TP）通过逻辑回归模型从图像特征中得出。应用剂量映射函数获取DPBN处方图，该图用于生成调强放射治疗（IMRT）治疗计划。剂量计算是在从MRI导出的伪CT上进行的。使用组内相关系数（ICC）量化计划流程的可重复性，比较了两个MRI检查之间的TP、DPBN图和IMRT剂量分布。用质量因子（QF）衡量每个治疗计划的质量。对于线性剂量映射，TP、DPBN图和IMRT剂量分布的ICC中位数分别为0.82、0.82和0.88；对于平方根剂量映射，ICC中位数分别为0.82、0.84和0.94。在所有治疗计划中发现QF中位数为3.4%。我们证明了DPBN放射治疗计划在前列腺癌中的稳定性，具有出色的总体可重复性和可接受的治疗计划质量。使用经过验证的肿瘤概率建模和简单的剂量映射技术表明，尽管成像数据存在每日变化，但仍可获得一致的治疗计划。
