Collimation is the act of restricting the size of the useful x-ray field to
the region of clinical interest. Doing so will reduce the radiation dose to the
patient. Proper collimation can also improve the contrast of the image by
reducing the amount of scattered radiation.
Dental Intra-oral x-ray units
For units operating above 50 kVp (all units at this facility fall into this
The x-ray unit is designed such that the diameter of the x-ray beam is
restricted to no more than 7 centimeters.
Cephalometric x-ray units
The x-ray field must not exceed the size of the image receptor (film).
Periodically inspect the edges of the patient images. The x-ray field should not
exceed the edge of the film in ANY direction. If the x-ray field does exceed an
edge of the film, notify
Radiation Safety for evaluation.
Panoramic x-ray units
The x-ray beam must fall within the aperture slit in front of the film. As
with the cephalometric units, the patient films should be inspected to verify
that the x-ray beam is contained within the film. If not, notify Radiation Safety