Radiography in Modern Industry - Kodak

such as a wall or floor, on the film side of the specimen may also scatter an appreciable quantityof x-rays back to the film, especially if the material receives the direct radiation from the x-raytube or gamma-ray source (See Figure 36). This is referred to as backscattered radiation.Figure 36: Intense backscattered radiation may originate in the floor or wall. Coning,masking, or diaphragming should be employed. Backing the cassette with lead may giveadequate protection.Reduction Of ScatterAlthough scattered radiation can never be completely eliminated, a number of means areavailable to reduce its effect. The various methods are discussed in terms of x-rays. Althoughmost of the same principles apply to gamma-ray radiography, differences in application arisebecause of the highly penetrating radiation emitted by most common industrial gamma-raysources. For example, a mask (See Figure 37) for use with 200 kV x-rays could easily be lightenough for convenient handling. A mask for use with cobalt 60 radiation, on the other hand,would be thick, heavy, and probably cumbersome. In any event, with either x-rays or gammarays, the means for reducing the effects of scattered radiation must be chosen on the basis ofcost, convenience, and effectiveness.Radiography in Modern Industry 51