基于KVCBCT形变配准的肺癌自适应计划与静态3DCRT计划的比较研究

Comparison of KVCBCT based on deformable image registration of adaptive planning and static 3DCRT planning for patients with lung cancer

目的对肺肿瘤利用千伏级锥形束CT（KVCBCT）图像形变配准的自适应放疗和静态三维适形放疗计划进行比较并评估差异。方法选5例肺肿瘤患者每3d行1次肺部CBCT扫描，每次扫描两组。把两组图像进行拼接获得10次CBCT拼接图像，将拼接图像和计划CT图像进行形变配准并获得10个新器官轮廓（CBCTf1～CBCTf10）。将CBCTf1～CBCTf10移植至计划CT图像上得到CBCTp1-CBCTp10累积剂量计划，并与CT计划的左右及双肺、脊髓、计划靶体积（PTV）的分次剂量、累积剂量和剂量体积直方图进行比较，差异行Wilcoxson符号秩检验。结果累积剂量计划的PTV最大、最小值，左右及双肺平均剂量，脊髓最大剂量，以及左右及双肺V5、V50、V20、V30、V50均〈CT计划（z=-2．02～-2．03，P均〈0．05）；但小平均剂量、95％ PTV接受剂量相似（z=-1．48、-1．21，P=0．138、0．225）。结论利用形变配准实施自适应放疗可降低肺组织和脊髓受量，提高PⅣ剂量，为进一步探索自适应放疗提供了一种方法。

Objective To comparison of kilo-voltage cone-beam CT （KVCBCT） deformable image registration of adaptive planning and static planning for patients with lung cancer, and evaluate their characters. Methods Five patients with lung cancer were in the study. Two sets image were acquired every three days and were concatenated to one set. Ten sets CBCT image and planning CT image were transferred a commercial deformable image registration software. The planning CT was deformed to each set CBCT and the contours delineated, the new contour were labeled CBCTfl-CBCTn0. Transfer of each deformed planning CT and CBCTn-CBCTn0 back into the treatment planning system enable re-calculation of actual dose distribution, then we obtain CT planning and fractional CBCT contour planning, the CBCT planning were labeled CBCTp1-CBCTp10. Ten times CBCT planning of every patient were added to acquire a total dose accumulation planning （ DA plan）, comparison of dose distribution and dose-volume histogram in CT plan and DA plan for fractionation dose and accumulation dose of left, right, total lung, PTV and spinal-cord. The difference of two plan was analyzed by Wilcoxson＇s sign rank test. Results The max and min dose of PTV, the left, right, total lung Vs, V10, V20, V30, V50, spinal-cord max dose, and the left, right and total lung mean dose in DA plan were smaller than in CT plan （z = - 2. 02 - - 2.03, P 〈 0.05 ）. The mean dose of PTV and D95 in DA plan was as well as in CT plan （z= -1.48, -1.21,P=0.138,0.225）. Conclusions KVCBCT based deformable image registration of adaptive planning reduce the dose of lung and spinal-cord, and enhance the dose of PTV. This provides a tool for exploring adaptive radiotherapy strategies.