Journal of Dental Research, Vol 55, 148-153, Copyright © 1976 by International & American Associations for Dental Research Online Journals
Quasimonochromatic radiation for dental radiography
A. Huen, E. J. Sternglass, D. M. Mazzocco and W. G. Fischer
Because of the greater sensitivity of commonly used dental films near 40 kv
and the inherently greater contrast between bone and other oral tissues
that is achieved at lower energies than those conventionally used, a
considerable reduction of radiation exposure can be obtained by the use of
those quasimonochromatic photons whose energy lies between 30 and 40 kv.
The simplest and clinically most efficacious and econimical method of
obtaining this quasimonochromatic radiation using fixed-anode tubes
involves the use of Ce, 0.008 inch in thickness, as a band-pass filter,
with reduction of skin exposure by a third to a half. The considerable dose
reduction achieved at an increased exposure time of only 1.2 seconds is
significant in view of the fact that both a greater percentage as well as a
greater number of people are receiving radiation for oral diagnosis every
year. Since the quasimonochromatic rays produced are less energetic than
much of the radiation in the unfiltered beam, the radiation doses from
scattered radiation to skull, bone marrow, and gonads also are reduced. In
addition, the softer photons result in less Compton scattering, reducing
the fog and improving the diagnostic quality of the film.
Quasimonochromatic radiation may also be used to enhance the contrast
wherever iodine contrast medium is needed since iodine absorbs very
strongly above its absorption edge near 33 kev, suggesting another use of
this technique in the area of oral diagnosis.
