摘要
目的:应用三维治疗计划系统评价GTV大小不同的鼻咽癌调强治疗计划的剂量分布,以探讨GTV变化对调强治疗剂量分布的影响。材料和方法:38例鼻咽癌患者,按GTV/CTV比值分为3组,GTV/CTV<10%为1组11例,10%<GTV/CTV<20%为2组15例,GTV/CTV>20%为3组12例,应用三维治疗计划系统设计调强放射治疗计划,根据剂量体积直方图(DVH)计算各组鼻咽癌靶区和正常组织剂量均数,对组间均数行T检验。结果:各组鼻咽癌靶区剂量分布均能满足靶区剂量要求,随着GTV/CTV比值增大,CTV最高剂量逐渐增高,3组与1组经检验有显著差异;GTV最高剂量变化趋势与CTV最高剂量变化相似,3组与1组、2组比较均有显著差异;GTV最低剂量随着GTV/CTV的增大,剂量逐渐降低;95%的GTV体积剂量1组高于2组;各组鼻咽癌的50%腮腺、1%脑干和1%脊髓的受照剂量经检验无显著差异,50%患侧晶体、1%视神经、50%垂体受照剂量3组显著高于1组。结论:(1)GTV/CTV比值可以更好的反应GTV分布,其值可初步预测靶区IMRT剂量分布情况,当GTV/CTV<10%时的剂量分布最均匀;(2)调强放射治疗适用于不同GTV的鼻咽癌患者,在满足靶区剂量要求的同时,减少了危及器官的受照剂量,使进一步提高靶区剂量成为可能;(3)当GTV/CTV>20%时,对危及器官的保护优势减小。
Purpose: To evaluate the influence of GTV on dosimetric distribution of intensity-modulated radiotherapy(IMRT) treatment planning for nasopharyngeal c arcinoma. Method and Materials: Thirty-eight patients were divided into three gr oups by different ratio of GTV/CTV. Group one (GTV/CTV<0.1) had eleven cases, Gr oup two (0.1<GTV/CTV<0.2) had fifteen cases,Group three(GTV/CTV>0.2) had twelve cases. IMRT treatment plans were designed for each of them and compared with res pect to target coverage, normal tissue sparing using dose-volume histogram(DVH). Result: No significant dosimetric disparity in the target volume was found amon g the different stages of nasopharyngeal carcinoma according to anticipated ther apeutic requirements, The maximum dose of CTV increased with elevation of GTV/CT V, particularly for Group three which was higher significantly than of Group one (P=0.003). Similar trends were observed for GTV; The minimum dose of GTV decreas e gradually with GTV/CTV increasing; Group one was significantly higher than of group two in the dose of 95% volume of GTV; With similar dose sparing of the 50% parotid gland, 1% spinal cord, 1% brain stem in three groups; Group three was s ignificantly higher than of Group two with respect to the dose of 50% volume of ipsilateral crystal, 1% optic nerve and 50% pituitary gland. Conclusion: (1)Th e ratio of GTV/CTV in place of GTV better predicted the distribution of target d ose. The distribution of target dose were the most homogeneous in GTV/CTV<10% gr oup;(2)IMRT is beneficial in treating all volume of GTV of nasopharyngeal carcin oma because of its dosimetric advantages. IMRT techniques provide improved tumor target coverage with significantly better sparing of sensitive normal tissue st ructures in the treatment of nasopharyngeal carcinoma. And allows room for dose escalation.(3)The sparing advantage of organ at risk is not significantly in GTV /CTV>20% group.
出处
《中国医学物理学杂志》
CSCD
2005年第2期438-440,共3页
Chinese Journal of Medical Physics
关键词
鼻咽癌
调强放射治疗
剂量体积直方图
nasopharyngeal carcinoma
intensity-modulated radiotherapy
dose-volu me histogram
