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目的分析诱导化疗前后鼻咽癌肿瘤体积的变化,及靶区和正常组织剂量分布的变化。方法自2009年3月至2010年8月收治12例经病理证实的初治局部晚期鼻咽癌患者,调强放疗前接受PF方案诱导化疗2周期。对患者诱导化疗前作CT模拟定位扫描后行靶区勾画和制定诱导化疗前调强放疗(IMRT)计划。2周期诱导化疗后进行第2次CT扫描,并将两次CT图像进行融合后测量肿瘤体积和制定诱导化疗后IMRT计划。采用配对t检验分析诱导化疗前后扫描肿瘤体积的变化,及靶区和正常组织剂量分布的变化。结果诱导化疗前和后原发灶GTVnx平均体积分别为(39.75±19.17)cm3和(25.65±15.11)cm3(t=4.203,P=0.001);颈淋巴结GTVnd(33.78±28.9)cm3和(15.56±14.91)cm3(z=2.94,P=0.003);原发灶+颈淋巴结GTV(73.53±31.55)cm3和(41.2±24.06)cm3(t=4.753,P=0.001);诱导化疗使肿瘤总体积减少了52.9%。66.5 Gy等剂量线所包括的体积分别为(302.0±110.3)cm3和(248.4±79.0)cm3(P=0.023),63 Gy等剂量线所包括的体积分别为(413.2±117.4)cm3和(409.1±115.1)cm3(P=0.097)。诱导化疗使T和N分期降低达33.3%和50%。结论诱导化疗前后肿瘤体积变化较大,按化疗后肿瘤勾画GTV的调强放疗能使高剂量区体积减少。
Objective To analyze the change of tumor volume of nasopharyngeal carcinoma before and after induction chemotherapy and the change of dose distribution in target area and normal tissue. Methods From March 2009 to August 2010, 12 patients with locally advanced nasopharyngeal carcinoma confirmed by pathology were treated with PF regimen for 2 cycles of induction chemotherapy before IMRT. Before the patient induction chemotherapy for CT simulation positioning scanning line target area outlined and the development of induction chemotherapy before IMRT plan. Two cycles of induction chemotherapy followed by a second CT scan and two CT images were fused to measure the tumor volume and to develop a post-induction chemotherapy schedule for IMRT. Paired t-test was used to analyze the change of tumor volume before and after induction chemotherapy and the change of dose distribution in target area and normal tissue. Results The average volume of GTVnx in the primary tumor before and after induction of chemotherapy was (39.75 ± 19.17) cm3 and (25.65 ± 15.11) cm3 respectively (t = 4.203, P = 0.001) (73.53 ± 31.55) cm3 and (41.2 ± 24.06) cm3, respectively (t = 4.753, P = 0.001). The induction of chemotherapy decreased the total volume of the tumor 52.9%. The volumes included in the 66.5 Gy iso-dose line were (302.0 ± 110.3) cm3 and (248.4 ± 79.0) cm3, respectively (P = 0.023). The volumes covered by the 63 Gy isoelectric dose line were (413.2 ± 117.4) cm3 and ± 115.1) cm 3 (P = 0.097). Induction chemotherapy reduced T and N staging by 33.3% and 50%. Conclusion The volume of tumor before and after induction of chemotherapy varies greatly. According to the GTV intensity modulation radiotherapy of tumor after chemotherapy, the volume of high dose area can be reduced.