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Biomedical subjects

W G Fischer

Publications and source records attributed to W G Fischer.

5 recordsLinked to original sources
PubMed1975

Anticipation of dental anomalies induced by radiation therapy.

Therapeutic irradiation of the head and neck of children up to the age of 16 years can cause malformation and developmental arrest of the permanent teeth. Dental anomalies occurring after irradiation of the palatal tumor in an 8-year-old are described and compared with a normal 8-year-old's developmental sequence to demonstrate that the immature, noncalcified dental structures are most susceptible to radiation injury. The stage of dental development at the time of therapy may be precisely determined by a routine oral radiographic survey, which provides a reliable estimate of the deformation that may be anticipated following radiotherapy.

Child↗
PubMedDate not supplied

Quasimonochromatic radiation for dental radiography.

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.

Filtration↗