Forsberg H
Acta Radiol. 1987 Jan-Feb;28(1):121-7.
The clinical demands for accuracy of roentgen generator scales were investigated in order to define suitable levels of tolerance to be required during calibration procedures and preventive maintenance on modern equipment. Radiographs of various film densities were made of four body parts. As test observers 59 radiologists and 53 radiologic technicians were asked to judge which radiographs they considered acceptable or not acceptable. Ninety-five per cent of the radiographs were accepted with the under- or overexposure of one mAs step. The spread of the estimations of suitable exposure data made by 38 radiologic technicians was also investigated. From these data the clinically acceptable tolerance of roentgen generator exposure parameters could be derived. It is suggested that the tolerance of tube voltage (kV) should be less than +/- 5 per cent, current-time product (mAs) -20 to +25 per cent and automatic exposure control systems (AEC) -20 to +25 per cent.
为了确定现代设备校准程序和预防性维护期间所需的合适公差水平，对X射线发生器刻度准确性的临床要求进行了调查。对四个身体部位拍摄了不同胶片密度的X光片。作为测试观察者，59名放射科医生和53名放射技师被要求判断他们认为哪些X光片是可接受的或不可接受的。95%的X光片在曝光不足或过度曝光一个mAs步长的情况下被接受。还调查了38名放射技师对合适曝光数据估计的离散情况。从这些数据中可以得出X射线发生器曝光参数的临床可接受公差。建议管电压（kV）的公差应小于±5%，电流-时间积（mAs）为-20%至+25%，自动曝光控制系统（AEC）为-20%至+25%。
