For those offices using digital technology, whether Computed Radiography (CR) or Direct Radiography (DR), the following points should be considered:

  1. PART CENTERING - the body part being radiographed should be in the center of the cassette of the CR plate or DR detector. If the body part is at the periphery of the image receptor (IR) the image cannot be adequately formed by the computer.
  2. SPLIT CASSETTES - if a CR plate is split into 2 parts, the side not receiving the exposure should be covered by a lead shield. Storage phosphors in the CR plate are extremely sensitive to low levels of exposure and may cause a “pixilated” effect.
  3. COLLIMATION - in digital systems, the computer software becomes inundated with information from the phosphor crystals at the edges of the image receptor as well as the area of the central ray. At the very least, the collimated field should be placed so that all four margins are placed on the IR.
  4. OPEN CASSETTES - with CR plate technology, the latent image is stored in the phosphor crystal and accidentally opening the cassette starts the erasure process, but a lag time of 15 seconds is normal.
  5. GRIDS - Image Receptors are more sensitive to scatter radiation.



  1. Merrill’s Atlas of Radiographic Positioning & Procedures 11 Ed. 2007

Contact ACRRT

American Chiropractic Registry
Radiologic Technologists

52 W. Colfax Street
Palatine, Illinois

Telephone: 847.705.1178


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