One of the important factors affecting radiographic image quality is the scattered radiation arising from the interaction of the photons with the object being radiographed. A large amount of scattered radiation results in the reduction of image contrast. In order to investigate the effects of scattered radiation, we have measured the angular dependence of the responses of the planar Ge detector for the obliquely incident photons.
Our investigation established that the aotive area of, a 6 mmφ×5mm deteotr is 3 mm in diameter and the available. incident angle is within 20°In this region, the measured spectra were successfuly corrected with the monoenergetic response functions calculated by using the Monte Carlo method for a pencil beam of photons impinged normally on the center of the planar Ge detector.
When a grid is used to avoid scatter, obliquely incident scatter is limited. When a grid of the ratio 5: 1 is used, the scatter of incident angle of more than 11°coming crossly to the leaves is removed. Even if the scatter of incident angle of more than 20°is removed by a suitable collimator pinhole, the diagnostic X-ray spectra made using a grid can be measured with a bit of error
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