Hughes G M
Radiology. 1980 Jun;135(3):699-703. doi: 10.1148/radiology.135.3.7384458.
Data from 521 computed tomography (CT) units show that 61% do not have the capacity to meet the current national guideline of 2,500 examinations per year. Capacity is primarily determined by study mix, such as head or body, without and/or with contrast agent. A new guideline accommodating this finding, using a scale of head equivalent CT (HECT) units, is proposed. The recommended annual level of 3,000 HECT units is based on the capacity of two-thirds of the 441 responding hospitals, whose units are staffed 52.4 hrs/wk, 75% of which are actually available for examinations. Twenty-five per cent of scans on body units are body studies, 39% of which are double studies and 35% only contrast enhanced studies; 70% of the head studies are double studies, and 16% are done with contrast agent alone. On head units the corresponding values are 58% and 20%.
来自521台计算机断层扫描（CT）设备的数据显示，61%的设备没有能力达到目前每年2500例检查的国家指导标准。设备能力主要由检查类型组合决定，例如头部或身体检查，有无使用造影剂。针对这一发现，提出了一项新的指导标准，采用头部等效CT（HECT）设备数量的衡量尺度。建议的每年3000 HECT设备数量的标准是基于441家回复医院中三分之二医院的设备能力，这些医院的设备每周工作52.4小时，其中75%的时间实际可用于检查。身体部位检查设备的扫描中，25%是身体检查，其中39%是重复检查，35%只是增强造影检查；头部检查中70%是重复检查，16%仅使用造影剂进行检查。在头部检查设备上，相应的比例分别为58%和20%。
