Hay G A, Cowen A R
Br J Radiol. 1981 Jan;54(637):24-8. doi: 10.1259/0007-1285-54-637-24.
The performance of a commercial panel-type X-ray image intensifier has been investigated by physical methods, both objective and subjective. The objective measurements show that the manufacturer's claims are justified, except perhaps in regard to contrast loss. The subjective measurements reveal that the conversion factor ("gain") of the device is such that dark-adaptation is not necessary, though best results are obtained in a nearly dark room. Hence the device confers a significant advantage, both in information and in dose to the patient, over traditional fluoroscopy. However, the conversion factor is nearly three orders of magnitude smaller than that of a conventional X-ray image-intensifier television system. Therefore, at modern fluoroscopic exposure rates, the eye is operating at light levels at which its own deficiencies set a limit to the perceptible information. To equal the performance of modern fluoroscopy the exposure rate to the intensifier must be increased to about 20 times the value customary in modern fluoroscopy. This can be done only by increasing the X-ray factors (kV and mA), resulting in a corresponding increase in dose to the patient of about one order of magnitude. Such an increase is in many circumstance unacceptable.
已通过客观和主观的物理方法对一种商用平板型X射线图像增强器的性能进行了研究。客观测量结果表明，制造商的说法是合理的，可能对比度损失方面除外。主观测量结果显示，该设备的转换因子（“增益”）使得无需暗适应，不过在近乎黑暗的房间里能获得最佳效果。因此，与传统荧光透视法相比，该设备在信息和给患者的剂量方面都具有显著优势。然而，其转换因子比传统X射线图像增强器电视系统的转换因子小近三个数量级。所以，在现代荧光透视曝光率下，眼睛所处的光照水平会使其自身的缺陷对可感知信息设置限制。要达到现代荧光透视法的性能，必须将增强器的曝光率提高到现代荧光透视法常用值的约20倍。这只能通过增加X射线参数（千伏和毫安）来实现，这会导致给患者的剂量相应增加约一个数量级。在许多情况下，这样的增加是不可接受的。
