Scattered radiation and characteristic film curve.

It is well known that scattered radiation has both favorable and adverse effects on the diagnostic image. The favorable effect consists of the increased intensity of x-rays after passing through strongly absorbent objects. In turn, the image is adversely affected by the decrease of contrast in the “straight-line” portion of the film curve. Depending on the radiologist's approach, emphasis is mostly either on visualizing as large a subject range as possible or on rendering maximum contrast. Basically, the interrelations between scattered radiation and characteristic film curve have been known for some time, but nevertheless incorrect descriptions continue to appear. The following comments are calculated to clarify matters and to contribute to the quantitative understanding of the problem. Subject Contrast and Subject Range The effects brought about when a homogeneous phantom is traversed by x-rays have been dealt with frequently in recent times (1, 2). Radiologists therefore have a sufficient knowledge of ...