| 摘要 |
Method of calibration of a radiology apparatus of the type comprising a source of radiation of the X-ray beam, the X-ray beam being manifested by a flow of photons, that radiation consisting of X photons, a means of detection of the X-ray beam after it has crossed the organ to be visualized, image acquisition and processing means capable of supplying an image signal I and a means of visualization connected to the means of detection. The mean m and the variance sigma <2> of the image signal are calculated, the mean m and the variance sigma <2> being respectively equal to kN and to k<2>N by reason of the Poisson distribution, N being the number of photons on input of the detection device; the value of N and the value of a coefficient f are derived, f being the apparent gain of the radiology apparatus with B = fxN, B being a variable representing the intensity of the image; one then derives an index of X-ray dose having to be emitted by the radiation source in order to obtain on output an image satisfying predetermined quality thresholds. |
