舌鳞癌术后常规和调强三维放疗计划的剂量学研究

Dosimetric study of three dimension therapy plans in patients with squamous cell carcinoma of tongue receiving postoperative intensity-modulated radiotherapy or conventional radiotherapy

目的通过舌鳞癌术后常规放疗(CRT)和调强放疗(1MRT)患者三维放疗计划的剂量学比较研究,对两组患者放疗靶区和危及器官(OARs)的剂量分布进行评价。方法将35例舌鳞癌患者分为CRT组(n=17)和IMRT组(n=18)。两组患者经热塑面罩固定、CT模拟定位、靶区和OARs勾画后,完成三维放疗计划和通过剂量验证。采用容积剂量图(DVH)、适形指数(CI)和均匀指数(HI)等剂量学研究方法,比较两组患者放疗计划靶区和OARs的剂量分布。结果CRT组和IMRT组95%靶区体积的剂量线值(D_(95))、CI、HI、最低剂量和最高剂量的差异有统计学意义(P<0.01),靶区平均剂量差异无统计学意义(P>0.05);IMRT组的唾液腺(双侧腮腺和对侧颌下腺)剂量明显低于CRT组(P<0.01)。结论舌鳞癌术后IMRT靶区剂量分布和降低唾液腺剂量方面显著优于CRT。

Objective To evaluate the dose distribution in clinical target volume （CTV） and organs-at-risk （OARs） in three dimension therapy plans in patients with squamous cell carcinoma of tongue receiving postoperative intensity-modulated radiotherapy （IMRT） or conventional radiotherapy （CRT） by dosimetric study. Methods Thirty-five patients with squamous cell carcinoma of tongue were divided into CRT group（n = 17） and IMRT group（n = 18）. All patients underwent head-and-neck immobilization with a thermoplastic mask and planning CT scan, and target volume and OARs were contoured. Dose calculation and plan optimization were performed. All three dimension plans passed quality assurance before treatment. The dosimetry of therapy plans with IMRT or CRT in target volume and OARs dose distribution was compared by dose-volume histogram （DVH）, conformity index （CI） and homogeneous index （ HI）. Results There were significant differences in D95（isodose line to cover 95 percent target volume）, CI, HI, minimum dose and maximum dosein CTV of therapy plans between patients with IMRT and CRT（P 〈 0.01）, and there was no significant difference in mean dose of CTV（P 〉 0.05）. The radiation dose on salivary glands （both parotid glands and contralateral submandibular gland） in patients with IMRT was significantly lower than that in patients with CRT（P 〈 0.01）. Conclusion Compared with dose distribution of CRT plans, there are more advantages in improving dose distribution at the target volume and sparing salivary glands in IMRT therapy plans in patients with squamous cell carcinoma of tongue.