鼻咽癌调强放疗中肿瘤、解剖结构变化及对剂量的影响

发布时间：2018-11-23 19:34

【摘要】：目的:通过对鼻咽癌调强放疗患者每周行一次CBCT扫描,观察肿瘤、解剖结构的体积和位置的变化,并研究因其变化对剂量分布产生的影响。方法:利用直线加速器自载CBCT,每周采集鼻咽癌患者调强放疗中的CBCT影像,分析患者GTVnx、GTVnd、体表轮廓、腮腺、颌下腺等相关解剖结构体积及位置动态变化。在放疗第21次时再次对患者行CT扫描,再勾画靶区和危及器官,将基于初始CT设计的调强计划射野导入到新扫描CT中,利用TPS计算比较因解剖结构变化导致的PGTVnx、PGTVnd、腮腺、颌下腺、脊髓、脑干剂量变化情况。结果:GTVnx、GTVnd、体表轮廓、腮腺、颌下腺等解剖结构的体积逐步退缩、位置发生移动,在第21次放疗前后时变化较显著。除GTVnx变化与初始体积无关外,余均与其初始体积大小正相关。放疗21次时,因各种解剖结构变化后,PGTVnd剂量(D95)平均降低169.55 cGy,双侧腮腺剂量(Dmean)增加175.70cGy、147.45cGy,双侧颌下腺剂量(Dmean)增加391.15cGy、479.25cGy,脊髓剂量(Dmax)增加68.55cGy,差异均有统计学意义(P0.05);PGTVnx剂量D95、脑干剂量Dmax变化不明显,无统计学差异(P0.05)。体表轮廓体积变化与腮腺、GTVnd的体积变化显著正相关(P0.05),与PGTVnd、腮腺、颌下腺、脊髓剂量变化有显著相关性(P0.05)。结论:放疗中解剖结构体积缩小、位置改变,致PGTVnd剂量降低,腮腺、颌下腺、脊髓剂量增加。体表轮廓变化能一定程度上反映靶区和危及器官体积和剂量学变化,是鼻咽癌放疗中一个敏感观察指标。
[Abstract]:Objective: to observe the volume and location of tumor and anatomical structure in patients with nasopharyngeal carcinoma (NPC) treated by intensity modulated radiotherapy (IMRT) once a week, and to study the effect of these changes on dose distribution. Methods: the CBCT images of patients with nasopharyngeal carcinoma (NPC) were collected weekly by linear accelerator self-loaded CBCT, and the volume and location of GTVnx,GTVnd, anatomical structures such as body surface contour, parotid gland and submandibular gland were analyzed. At the 21st time of radiotherapy, the patients were scanned with CT again, and then the target area and the dangerous organs were delineated. The intensity modulated field based on the initial CT design was introduced into the newly scanned CT. The PGTVnx,PGTVnd, parotid gland caused by the anatomic structure change was compared by TPS calculation. Changes of submandibular gland, spinal cord and brain stem dose. Results: the volume of body surface outline parotid gland and submandibular gland of GTVnx,GTVnd, gradually retreated and the position changed significantly before and after 21st radiotherapy. Except for the change of GTVnx which is independent of the initial volume, the remainder is positively correlated with its initial volume. After 21 times of radiotherapy, the average dose of PGTVnd (D95) decreased by 169.55 cGy, the dose of (Dmean) increased by 175.70 cGy (147.45 cGy), the dose of bilateral submandibular gland (Dmean) increased by 391.15cGy (479.25cGy) after 21 times of radiotherapy. The spinal cord dose of (Dmax) increased 68.55 cGy, the difference was statistically significant (P0.05). PGTVnx dose D 95, brainstem dose Dmax changes were not significant, there was no statistical difference (P0.05). The volume of body surface contour was positively correlated with the volume of parotid gland and GTVnd (P0.05), and was significantly correlated with PGTVnd, parotid gland, submandibular gland and spinal cord dose change (P0.05). Conclusion: the volume of anatomical structure was reduced and the position changed during radiotherapy, which resulted in the decrease of PGTVnd dose, the increase of the dose of parotid gland, submandibular gland and spinal cord. The change of body surface profile can reflect the changes of target area and organ volume and dosimetry to some extent, and is a sensitive index in radiotherapy for nasopharyngeal carcinoma (NPC).
【学位授予单位】：南昌大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：R739.63

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