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X 线倾斜角度或胶片倾斜角度(X 线不与胶片垂直),对胶片的感光效应(P,E)有一定影响。根据感光效应的公式:P,E=(mA×T×KV~2)/D~2如果 X 线作为点光源,在单位立体角内的截面积很小时,X 线可认为均匀地垂直照射,那么 X 线的毫安(mA),时间(T)和仟伏(KV)均不变,则 X线胶片感光效应与距离(D)的平方成反比。这就是X线摄影技术教科书常引用的一个公式,并适用于X线垂直于胶片的投照。在实际摄影工作中,X 线不与胶片垂直的部位颇多,为此我们对胶片感光效应的公式作以下推
X-ray tilt angle or film tilt angle (X-ray is not perpendicular to the film), the film’s photosensitive effect (P, E) have an impact. According to the formula of sensitometric effect, if X-ray is used as a point light source and the cross-sectional area in unit solid angle is very small, the X-ray can be considered to be uniformly irradiated vertically. X-ray film sensitivity is inversely proportional to the square of distance (D), since the mA, T, and KV of the X-ray are constant. This is a formula often quoted in x-ray photography textbooks and is suitable for projection of X-rays perpendicular to the film. In the actual photography work, the X-ray film is not a lot of vertical parts, for which we film sensitometric effect of the following formula