부산대학교 도서관

(Introduction) Since the discovery of X-rays in 1895 and their first application to medical treatment, elucidation of the nature of X-rays scattered by the subject has been an important question. Scattered X-rays reduce the contrast of a film and lower its value for diagnostic purposes. Therefore, various studies have been made to develop some useful apparatus for eliminating such scattered X-rays, and as a result, the image quality of X-ray photographs has been considerably improved. These scattered X-rays are not entirely ineffective; some of them can be put to good use. It is not necessary, therefore, to eliminate these scattered X-rays completely, rather, the correlation between the content of scattered X-rays and the image quality should be elucidated so that such results may be utilized according to the needs. In the study of this correlation, the optical transfer function was used.(Conclusion) (1) The greater the content of acattered X-rays and the MFD, the lower the response. When the content is 100per cent, the response is almost zero. (2) The response of scattered X-rays is almost constant irrespective of the spatial frequency. (3) Theoretically, X-ray films used for everyday clinical purposes have lower values of response due to scattered X-rays. To improve the image quality, these scattered X-rays have to be eliminated, but it is not always wise to try to remove them completely. It is more important to achieve a good balance between the content of scattered X-rays and the image quality, depending on the diagnostic purpose.