影像引导的自适应放疗在鼻咽癌治疗中的剂量学研究

Dosimetric study of adaptive radiotherapy for nasopharyngeal carcinoma

对7例经病理确诊的初治鼻咽癌患者采用西门子ARTISTE图像引导的自适应放疗系统进行治疗规划，患者均采用同步整合加量调强放疗（SIB-IMRT）技术（作为IMRT组），放疗10次后对所有患者进行第2次CT断层扫描，并以此重新勾画靶区设计新的计划（ARTl）；第21次后进行第3次CT断层扫描，并以此重新勾画靶区设计新的计划（ART2）。治疗结束后进行第4次CT断层扫描。分别比较3组计划的靶区和危及器官的体积变化及剂量学差异。结果显示，放疗过程中肿瘤体积和腮腺体积都明显缩小，并且两侧腮腺的外侧界向中心平均位移为4．5（1．6～9．2）mm。3种计划的肿瘤靶区剂量差异无统计学意义。与IMRT相比，ART1左右侧腮腺平均剂量分别减少了0．42Gy（1．68％）（P=0．019）和0．79Gy（3．04％）（P=0．013），ART2相对于ART1，左右腮腺平均剂量再次减少分别为0．86Gy（3．50％）（P=0．001）和1．04Gy（4．13％）（P=0．035）。

Seven patients with nasopharyngeal carcinoma treated with ART were recruited. All patients were treatedwith SIB-IMRT regimen（ named IMRT）. All patients had a second computed tomography scan after 10 fractions and a new plan based on this was initiated from fraction 11 （ART1）. And a third CT scan after 21 fractions and a new plan based on this was initiated from fraction 22 （ART2）. When the treatment was finished, a fourth CT scan was made. Results revealed that the volumes of primary tumors and parotid glands regressed significantly after the teat- ment. The position of the parotid glands shifted medially an average of 4. 5 （ 1.6 - 9. 2） mm during the plans. ART1 reduced mean dose to left parotid by 0.42 Gy（ 1.68% ） （P =0. 019） and right parotid by 0.79 Gy （3.04%） （P =0.013） over the IMRT alone. ART2 further reduced the mean left parotid dose by 0.86 Gy or 3.5% （P = 0. 001） and right parotid by 1.04 Gy or4.13% （P=0.035）.