基于 CT-CT 图像融合的鼻咽癌改良容积旋转调强自适应放疗。
A modified VMAT adaptive radiotherapy for nasopharyngeal cancer patients based on CT-CT image fusion.
机构信息
Radiotherapy and Chemotherapy, Department of the 1st Affiliated Hospital of Wenzhou Medical University, No,2 Fuxue Lane, Wenzhou 325000, China.
出版信息
Radiat Oncol. 2013 Nov 27;8:277. doi: 10.1186/1748-717X-8-277.
BACKGROUND
To investigate the feasibility and benefits of a modified adaptive radiotherapy (ART) by replanning in the initial CT (iCT) with new contours from a repeat CT (rCT) based on CT-CT image fusion for nasopharyngeal cancer (NPC) patients underwent volumetric modulated arc radiotherapy (VMAT).
MATERIALS AND METHODS
Nine NPC patients underwent VMAT treatment with a rCT at 23rd fraction were enrolled in this study. Dosimetric differences for replanning VMAT plans in the iCT and in the rCT were compared. Volumetric and dosimetric changes of gross tumor volume (GTV) and organs at risk (OARs) of this modified ART were also investigated.
RESULTS
No dosimetric differences between replanning in the iCT and in the rCT were observed. The average volume of GTV decreased from 78.83 ± 38.42 cm3 in the iCT to 71.44 ± 37.46 cm3 in the rCT, but with no significant difference (p = 0.42).The average volume of the left and right parotid decreased from 19.91 ± 4.89 cm3 and 21.58 ± 6.16 cm3 in the iCT to 11.80 ± 2.79 cm3 and 13.29 ± 4.17 cm3 in the rCT (both p < 0.01), respectively. The volume of other OARs did not shrink very much. No significant differences on PTVGTV and PTVCTV coverage were observed for replanning with this modified ART. Compared to the initial plans, the average mean dose of the left and right parotid after re-optimization were decreased by 62.5 cGy (p = 0.05) and 67.3 cGy (p = 0.02), respectively, and the V5 (the volume receiving 5 Gy) of the left and right parotids were decreased by 7.8% (p = 0.01) and 11.2% (p = 0.001), respectively. There was no significant difference on the dose delivered to other OARs.
CONCLUSION
Patients with NPC undergoing VMAT have significant anatomic and dosimetric changes to parotids. Repeat CT as an anatomic changes reference and re-optimization in the iCT based on CT-CT image fusion was accurate enough to identify the volume changes and to ensure safe dose to parotids.
背景
为了研究基于 CT-CT 图像融合的重复 CT（rCT）新轮廓引导下在初始 CT（iCT）中重新计划对接受容积调强弧形治疗（VMAT）的鼻咽癌（NPC）患者的改良自适应放疗（ART）的可行性和益处。
材料与方法
本研究纳入了 9 例在第 23 次分割时接受 rCT 的 NPC 患者。比较了在 iCT 和 rCT 中重新计划 VMAT 计划的剂量差异。还研究了这种改良 ART 中大体肿瘤体积（GTV）和危及器官（OARs）的体积和剂量变化。
结果
在 iCT 和 rCT 中重新计划时未观察到剂量差异。GTV 的平均体积从 iCT 中的 78.83±38.42 cm3 减少到 rCT 中的 71.44±37.46 cm3，但无统计学差异（p=0.42）。左、右腮腺的平均体积分别从 iCT 中的 19.91±4.89 cm3 和 21.58±6.16 cm3 减少到 rCT 中的 11.80±2.79 cm3 和 13.29±4.17 cm3（均 p<0.01），而其他 OAR 的体积变化不大。使用这种改良 ART 重新计划时，PTVGTV 和 PTVCTV 覆盖范围无显著差异。与初始计划相比，左、右腮腺在重新优化后的平均剂量分别降低了 62.5 cGy（p=0.05）和 67.3 cGy（p=0.02），左、右腮腺的 V5（接受 5 Gy 的体积）分别降低了 7.8%（p=0.01）和 11.2%（p=0.001）。其他 OAR 的剂量无显著差异。
结论
接受 VMAT 治疗的 NPC 患者的腮腺在解剖结构和剂量方面有显著变化。重复 CT 作为解剖变化的参考，基于 CT-CT 图像融合的 iCT 重新优化足以识别体积变化，并确保腮腺的安全剂量。
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