鼻咽癌调强放疗期间自适应放疗计划时机的研究

发布时间：2018-06-02 04:12

本文选题：鼻咽癌 + 调强放疗　；参考：《广西医科大学》2014年硕士论文

【摘要】：目的：本研究通过评估鼻咽癌(nasopharyngeal carcinoma, NPC)调强放疗(intensity-modulated radiation therapy, IMRT)期间各周的靶区及危及器官(organs at risk, OARs)解剖学及剂量学改变,研究自适应放疗(adaptive radiation therapy, ART)的最佳干预时机。材料与方法：对19名调强放疗的鼻咽癌患者每周进行重复CT扫描,方法与放疗前定位一致,在MIM Maestro图像软件中使用形变配准方法对原始定位CT与每周新CT进行CT-CT融合,自动勾画靶区及OARs,观察GTVnx、 GTVnd和腮腺的体积变化及腮腺质心位移。然后将初始放疗计划的剂量分布依次传递到新的CT图像上,形成每周合成计划剂量分布,对比合成计划与原始计划的剂量-体积直方图(dose-volume histogram,DVH),观察靶区及OARs在放疗过程中剂量学改变。结果：GTVnx、GTVnd、左侧腮腺和右侧腮腺体积在放疗结束时分别减少65.6±13.3%,72.7±13.3%,39.8±14.4%和37.4±15.5%,体重平均下降8.3±5.1%。与放疗前比较,左侧腮腺质心向中线明显位移0.27±0.25cm,向上位移0.14±0.20cm；右侧腮腺质心向中线明显位移0.31±0.19cm。体重下降与两侧腮腺体积缩小及质心向中线位移之间有明显的相关性,与GTVnx及GTVnd体积改变无相关性。与Plan0相比,PTVnx、PTVnd、PTV1和PTV2的各周合成计划的靶区均匀性指数(homogeneity index,HI)差异均无统计学意义,PTVnx、PTVnd、PTV1的Dmean、D95、V95、适形指数(conformity index,CI)在放疗过程中均呈上升趋势,且PTVnx、PTVnd的高量区V110没有明显增加。PTV2的Dmean与放疗前基本保持不变,但D95、V95、CI均明显呈下降趋势。放疗过程中的OARs如脑干、脊髓、腮腺、声门喉、右侧眼球、左侧晶体明显逐渐增加。放疗过程中靶区剂量下降及OARs剂量增加是由多种解剖学改变作用所引起的。结论：鼻咽癌调强放疗过程中发生显著的靶区及危及器官解剖学和剂量学改变,靶区剂量覆盖下降及危及器官超量与解剖学改变有明显的相关性。PTV2的D95、V95及CI、脑干Dmax、脊髓Dmax、腮腺Dmean及V30、声门喉Dmean、右侧眼球Dmax和左侧晶体Dmax可以作为评估自适应放疗时机的参数,经过分析建议在鼻咽癌调强放疗1周后及3周后分别进行ART计划优化。
[Abstract]:Objective: to evaluate the anatomical and dosimetric changes of intensity-modulated radiation therapy, IMRT) during intensity-modulated radiation therapy, IMRT) in nasopharyngeal carcinoma (NPC), and to study the optimal intervention time of adaptive radiation therapy, ART). Materials and methods: a total of 19 patients with nasopharyngeal carcinoma undergoing IMRT were scanned by repeated CT every week. The method was consistent with the localization before radiotherapy. CT-CT fusion was performed between the original CT and the new CT using deformation registration method in MIM Maestro image software. The volume changes of GTV nx, GTVnd and parotid gland and the centroid displacement of parotid gland were observed. Then the dose distribution of the initial radiotherapy plan is transferred to the new CT image in turn to form the weekly synthetic dose distribution. The dose-volume histogram was compared between the synthetic plan and the original plan. The dosimetric changes of target area and OARs during radiotherapy were observed. Results at the end of radiotherapy, the volume of the left parotid gland and the right parotid gland decreased by 65.6 卤13.3% and 39.8 卤14.4% and 37.4 卤15.5%, respectively, and the weight of the left parotid gland and the right parotid gland decreased by 8.3 卤5.1. The displacement of the centroid of the left parotid gland to the midline was 0.27 卤0.25 cm and the displacement of the center of the right parotid gland was 0.14 卤0.20 cm and 0.31 卤0.19 cm / cm respectively. There was a significant correlation between weight loss and bilateral parotid volume reduction and centroid displacement, but not with GTVnx and GTVnd volume changes. There was no significant difference in homogeneity index between PTVnxX PTVnd1 and PTV2. The conformability index of PTVnxPTV1 was on the rise during radiotherapy. The conformity index of PTVnd1 and PTVnd1 showed an increasing trend during the radiotherapy process, and there was no significant difference in homogeneity index between PTVnxX PTVnd1 and PTV95V95, the conformity index of PTVnd1 and PTV2 showed an upward trend during radiotherapy, and the conformity index of PTV1 showed a trend of increase in the course of radiotherapy. Moreover, the Dmean of PTV2 in the high volume region of PTVnd did not increase significantly, but D95 V95 CI decreased significantly. OARs such as brain stem, spinal cord, parotid gland, glottic larynx, right eyeball and left lens increased gradually during radiotherapy. The decrease of target dose and the increase of OARs dose during radiotherapy are caused by various anatomical changes. Conclusion: significant changes in target area and organ anatomy and dosimetry were observed during intensity-modulated radiotherapy for nasopharyngeal carcinoma. D95V95 and CIof PTV2, Dmaxin brain stem, Dmaxin spinal cord, Dmean and V30 in parotid gland, Dmean in glottic larynx, Dmax in right eye and Dmax in left lens can be used as parameters to evaluate the time of adaptive radiotherapy. It was suggested that the ART plan should be optimized after 1 week and 3 weeks after intensity modulated radiotherapy for nasopharyngeal carcinoma.
【学位授予单位】：广西医科大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：R739.63

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