利用CBCT图像监测鼻咽癌放疗腮腺和外轮廓体积变化

Monitoring the Volume Changes of Parotid Gland and External Contour in Nasopharyngeal Carcinoma with CBCT Images

目的利用CBCT图像探讨鼻咽癌调强放疗(IMRT)中解剖学动态变化规律。方法随机选取实际接受IMRT的鼻咽癌患者30例,利用疗程中CBCT图像,由肿瘤放疗主治以上医生和影像医生对30例患者的腮腺进行勾画和患者外轮廓范围的确定,由物理师计算出腮腺和外轮廓的体积。结果在CBCT图像上,鼻咽癌IMRT放疗中腮腺、外轮廓体积逐步缩小。第3周腮腺体积缩小2.71~13.14 cm^3(中位值6.79 cm^3),第5周缩小6.77~15.86 cm^3(中位值9.16 cm^3),当放疗至第五周以后腮腺体积变化趋于平坦;外轮廓体积第3周缩小4.3~79.78 cm^3(中位值40.19 cm^3),第5周缩小15.67~130.61 cm^3(中位值52.34 cm^3)。结论利用CBCT图像可以监测鼻咽癌IMRT放疗中腮腺、外轮廓体积变化,和利用扇形束CT的研究结论是一致的,即鼻咽癌IMRT放疗中腮腺、外轮廓体积逐步缩小,可作为鼻咽癌自适应治疗提供依据。

Objective To study the dynamic change of anatomy during intensity modulated radiation therapy(IMRT)for nasopharyngeal cancer(NPC).Methods 30 NPC patients were randomly selected from those who actually received IMRT.Using the CBCT images during the course of treatment,the parotid glands of 30 patients were sketched and the external contour of the patients were determined by physicians and imaging doctors.Calculate the volume of the parotid gland and the external contour by the physicist.Results On CBCT images,the volume of parotid gland and outer contour decreased gradually during IMRT of nasopharyngeal carcinoma(NPC).The parotid volume decreased 2.71~13.14 cm^3(median 6.79 cm^3)in the third week and 6.77~15.86 cm^3(median 9.16 cm^3)in the fifth week.The volume of parotid gland tended to flatten after the fifth week of radiotherapy.The volume of external contour reduced 4.3~79.78 cm^3(median 40.19 cm^3)in the 3rd week and reduced 15.67~130.61 cm^3(median 52.34 cm^3)in the 5th week.Conclusion CBCT images can be used to monitor the volume changes of parotid gland and external contour in IMRT radiotherapy of NPC,which is consistent with the conclusion of using fan bundle CT,which can provide a basis for adaptive treatment of NPC.