Abstract: A system of radiography includes the provision of a cassette which is to be subjected to exposure from radiation beam. The cassette includes a screen layer and a filter layer having regions of different optical density and an imaging film. The filter acts to reduce the exposure of the film to the effect of radiation. The cassette is useful for dental images, particularly of the temporamandibular joint.

Abstract: Heat build up is reduced in x-ray film illuminator apparatus by transferring excess heat from the sources thereof to the exterior of the unit and then into the surrrounding environment. A heat dispersing surface contacts the hottest part of the ballast employed within the unit, with a back wall of the unit itself being spaced from an associated wall, on which the apparatus may be detachably mounted on a special hanger so as to permit a vertical air flow path between the back wall and associated mounting wall surface. A viewing area of the unit is formed by a translucent face plate retained in position along at least the top or upper peripheral portion thereof by a resilient element also capable of retaining in place the film transparency or other media that is being viewed.