Graham L S
West Los Angeles Veterans Administration Medical Center, CA 90073, USA.
Radiographics. 1995 Nov;15(6):1471-81. doi: 10.1148/radiographics.15.6.8577970.
A comprehensive set of acceptance tests is the basis for an effective quality control program. Acceptance tests indicate whether the scintillation camera meets published specifications but should also include evaluation of certain parameters not specified by the vendor but that can seriously affect image quality. Once a camera is "accepted," initial quality control tests serve as a benchmark for future measurements. Tomographic systems must be subjected to the same basic quality control program as planar cameras. Flood field images must be acquired and evaluated daily; spatial resolution must be tested once each week. Less frequently, parameters such as multiple-window spatial registration, collimator uniformity, system sensitivity, and camera "dead time" should be evaluated. Single photon emission computed tomographic systems require additional tests to ensure optimum performance. Center-of-rotation calibration and verification of detector registration are needed to avoid losses of spatial resolution. Flood corrections based on high-count images eliminate residual detector nonuniformiaties and correct for subtle collimator defects. Pixel size must be calibrated to avoid errors in attenuation correction and distortion when cardiac and brain reorientation software is used. Completed clinical studies must be checked for unacceptable patient movement and incomplete views. A quality control program may be time-consuming, but, from the standpoint of maximum benefit to patients and confidence in clinical interpretations, there is no alternative.
一套全面的验收测试是有效质量控制计划的基础。验收测试表明闪烁相机是否符合已公布的规格，但还应包括对某些未由供应商规定但可能严重影响图像质量的参数进行评估。一旦相机“验收合格”，初始质量控制测试就作为未来测量的基准。断层扫描系统必须接受与平面相机相同的基本质量控制程序。必须每天采集并评估泛场图像；空间分辨率必须每周测试一次。对于多窗口空间配准、准直器均匀性、系统灵敏度和相机“死时间”等参数，应进行较少频率的评估。单光子发射计算机断层扫描系统需要额外的测试以确保最佳性能。需要进行旋转中心校准和探测器配准验证，以避免空间分辨率损失。基于高计数图像的泛场校正可消除探测器残留的不均匀性，并校正准直器的细微缺陷。必须校准像素大小，以避免在使用心脏和脑部重定位软件时在衰减校正和失真方面出现误差。必须检查已完成的临床研究，以查看是否存在不可接受的患者移动和不完整的视图情况。质量控制计划可能很耗时，但从给患者带来最大益处以及对临床解读有信心的角度来看，别无选择。
