X線撮影における斜入効果と幾何学的不鋭

抄録

In this study, the modulation transfer function (MTF) of oblique incidence effect and the MTF of geometric unsharpness were investigated. The MTF of oblique incidence effect is dependent upon the angle at which an X-ray beam is incident on a screen-film system, and the greater incidence angle get, the lower the MTF make. In addition, spurious resolution is produced at an angle of almost 20°. The total MTF is the sum of MTF of recording system and MTF of geometric unsharpness. The tota1 MTFs of magnification factor 1.1 at an incidence angle of 30° and magnification factor 1.2 at an incidence angle perpendicular to the screen-film system were compared. These total MTF have approximatery equal value with 1.3 mm focal spot employed. However, if a focal spot smaller than 1.3 mm is employed, the total MTF of magnification factor 1.2 at an incidence angle perpendicular to the screen-film system is better than the total MTF of magnification factor 1.1 at an incidence angle of 30°.