锥形束CT图像引导系统在放射治疗中的应用

CBCT image guided radiation therapy clinical application

目的:研究锥形束CT(CBCT)图像引导系统在精确放射治疗中提高摆位的精度,减少摆位的不确定性的作用。方法:对头颈部肿瘤患者(30例)和胸部肿瘤患者(40例)用CBCT扫描,其中头颈部肿瘤患者扫描90次,胸部肿瘤患者扫描113次,统计患者前后、头脚及左右方向的摆位偏差。结果:对于头颈部肿瘤患者前后方向的最大偏差值为6 mm,3个方向中>3 mm偏差的均在10%以下;对于胸部肿瘤患者的头脚方向摆位误差最大,>5 mm的达21.51%。前后方向的误差≤5 mm,左右方向>5 mm的为4.53%。结论:采用CBCT图像引导系统对患者体位实时修正,极大的提升了放射治疗的精度和疗效。相对于电子射野影像验证系统(EPID),CBCT对患者的累积剂量的影响更小,图像分辨率更高,图像匹配更精确,但是和普通螺旋CT相比,其分辨率和扫描范围还需要更进一步的提高。

Objective：Study the effect about cone beam CT（CBCT） image guidance sytem to improve the positioning accuracy and reducing the set-up uncertainty in precise radiotherapy. Methods：Use CBCT system to scan head and neck tumors patients （30 cases） and chest tumor patients （40 cases）, including head and neck tumor patients were scaned 90 times, chest tumor patients were scaned 113 times. Setup deviation statistics about anterior and posterior, head and feet, left and right direction. Results：The patients with head and neck cancer, the maximum error of anterior-posterior is 6mm, Three directions errors which greater than 3mm all less than 10%. Patients with chest tumor position error are in the head and foot direction, greater than 5 mm up to 21.51%. Before and after the direction of the error did not exceed 5mm. The left and right direction greater than 5 mm up to 4.53%. Conclusion：It greatly enhances the precision of radiotherapy, improved the curative effect of radiotherapy by using CBCT online image guidance system for the patient position correction. Compared with EPID, patients scaned with CBCT absorb smaller cumulative dose, the image resolution is higher, image matching is more accurate. But compared with the ordinary helical CT,the resolution and scanning range also need to improve.