Radiology, Vol 190, 525-528, Copyright © 1994 by Radiological Society of North America
Scanning slit chest radiography: a practical and efficient scatter control design
GT Barnes, X Wu and PC Sanders
Department of Radiology, University of Alabama Hospitals and Clinics, Birmingham.
PURPOSE: To design a chest radiography unit that eliminates scatter.
MATERIALS AND METHODS: A scanning slit radiography unit that also
incorporates a conventional grid was designed. The scanning slit geometry
defined a 10-mm-wide beam at the image receptor. RESULTS: With a typical
heavy-duty radiographic tube, the proposed system was capable of delivering
an entrance skin exposure of up to 32 microC/kg for a 1- second scan. Monte
Carlo simulations indicated that the scatter-to- primary ratio (S/P) imaged
with the scanning slit system alone was 0.125 for a 35 x 43-cm, 23-cm-thick
Lucite phantom imaged at 140 kVp. When the system was coupled with 4:1,
8:1, and 12:1 grids, S/P decreased to 0.063, 0.055, and 0.054,
respectively. CONCLUSION: A scanning slit system coupled with a
conventional grid is a practical and highly efficient method of controlling
scatter and will result in minimal soft-tissue and bone measurement errors
in dual-energy chest radiography.
