图像引导放射治疗系统锥形束CT的图像质量检测  

Study on the detection and analysis of image quality of CBCT in IGRT system

作　　者：刘春兰 孙小喆 郭雄芳 于美丽[2] LIU Chun-lan;SUN Xiao-zhe;GUO Xiong-fang(Department of Oncology,The Characteristic Medical Center of The Chinese Armed Police Force,Tianjin 300162,China)

机构地区：[1]武警特色医学中心肿瘤科,天津300162 [2]山东省职业卫生与职业病防治研究院,山东济南250002

出　　处：《中国医学装备》2023年第2期8-12,共5页China Medical Equipment

摘　　要：目的:研究直线加速器机载(OBI)图像引导放射治疗(IGRT)系统X射线发生器和非晶硅影像面板质量保证检测对锥形束CT(CBCT)图像质量的影响,确保图像配准位置验证的准确性。方法:采用IGRT系统分别对X射线摄影和透视模式下的管电压(kV)、管电流(mA)、毫安秒(mAs)实际值进行测量,利用TOR18FG型检测模体测量千伏级影像图像高对比分辨率和低对比分辨率,通过Catphan504测试模体中的CTP404、CTP528和CTP515的3个模块对CBCT图像进行测量校准验证检测,分析其图像密度分辨率、空间线性度距离测量、图像均匀性、高分辨率和低对比分辨率及灵敏度。结果:在X射线摄影和透视模式下kV、mA及mAs预设值与实际测量值误差均<±5%;透视模式下高对比分辨率为可见线对数2 lp/mm;TOR18FG型检测模体的低对比灵敏度测试结果可见圆盘数为15个(对比度1.45%)。Catphan504模体的CTP404模块中被测物质CT值均为±40 HU内,空间线性度距离精度≤1%;高分辨率在CTP528模块中高剂量头扫描的分辨线对为7.0 lp/mm,骨盆扫描分辨线对为5.0 lp/mm。CTP515模块低对比度分辨率为6.0 lp/mm。结论:影像引导放射治疗系统中影响图像质量因素较多,为保证影像引导放射治疗中CBCT扫描图像质量,在临床应用中需定期进行IGRT系统的质量控制和质量保证。Objective: To study influences of X-ray generator of image guided radiation therapy(IGRT) system of on board imager(OBI) of linear accelerator and the detection of amorphous silicon(A-Si) image panel with quality guarantee on image quality of cone-beam computed tomography(CBCT), so as to ensure the accuracy of position verification of image registration. Methods: The IGRT system was adopted to respectively measure the actual values of tube voltage(kV), tube current(mA) and milliampere second(mAs) at X-ray radiography and fluoroscopy modes.The TOR 18FG detection phantom was used to measure the high and low contrast resolution rates of image with kV level, and Catphan504 was used to test the 3 modules(CTP404, CTP528 and CTP515) of phantom so as to conduct the detections of measurement, calibration and verification for CBCT images. And then, the resolution ratio of image density, the measurement of the distance of linearity of interspace, homogeneity of image, high resolution and the resolution of low contrast and sensitivity were further analyzed. Results: The errors between the preset values and the actually measured values of kV, mA and ms were all less than±5% under the X-ray and fluoroscopy mode. The high contrast resolution was the visible line pair 2 IP/mm under fluoroscopy modes. The number of visible disks in the test results of low-contrast sensitivity of TOR 18FG detection phantom was 15(contrast was 1.45%). The CT value of the tested substance in the CTP404 module of Catphan504 phantom was within ±40HU, and the precision of the distance of the spatial linearity was less than or equal to 1%. The line pair of high resolution of the scan with high dose on head in CTP528 module was 7.0 lp/mm, and the line pair of resolution of pelvic scan was 5.0 lp/mm. The resolution of low contrast of the CTP515 module was 6.0 mm. Conclusion: There are many factors affect image quality in IGRT system.In order to ensure the image quality of CBCT scan in IGRT, the quality control and assurance of IGRT system must be carrie

关 键 词：X射线发生器 非晶硅影像面板 锥形束CT(CBCT) 图像质量 

分 类 号：R816[医药卫生—放射医学]