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Theoretical and experimental studies of the influence of air kerma rate on threshold contrast in diagnostic fluoroscopy systems

Abstract

Experimental measurements of threshold contrast (Csub(T)) as a function of air kerma rate at the input plane of the image intensifier have been made for several diagnostic fluoroscopy units in clinical use. Threshold contrasts are determined by viewing a test object containing holes of fixed diameter and various depths under defined irradiation conditions. Kerma rate variations are effected by introducing aluminum sheets into the x-ray beam at fixed values of tube potential and current. At low kerma rates where quantum noise dominates, low tube potentials (60 kVsub(p)) usually yield lower values of Csub(T) than do higher potentials (100 kVsub(p)). At higher kerma rates the opposite is often true. A simple theoretical model for noise propagation in fluoroscopic imaging systems using models of diagnostic x-ray spectra lends qualitative support to the experimental findings. The often-quoted suggested upper limit of 100 ..mu..R s/sup -1/ (0.87 ..mu..Gy s/sup -1/) at the input phosphor would seem to be justified under the test conditions since little improvement in Csub(T) is usually observed at higher kerma rates. However, application to clinical practice would ideally require the use of more realistic phantom studies.
Authors:
Harrison, R M; Day, M J [1] 
  1. Newcastle upon Tyne Univ. (UK). Newcastle General Hospital
Publication Date:
Nov 01, 1983
Product Type:
Journal Article
Reference Number:
AIX-15-025743; EDB-84-075727
Resource Relation:
Journal Name: Phys. Med. Biol.; (United Kingdom); Journal Volume: 28:11
Subject:
42 ENGINEERING; 62 RADIOLOGY AND NUCLEAR MEDICINE; FLUOROSCOPY; RESOLUTION; AIR; DIAGNOSTIC TECHNIQUES; KERMA; NOISE; BIOMEDICAL RADIOGRAPHY; FLUIDS; GASES; MEDICINE; NUCLEAR MEDICINE; RADIOLOGY; 420500* - Engineering- Materials Testing; 550602 - Medicine- External Radiation in Diagnostics- (1980-)
OSTI ID:
5028697
Country of Origin:
United Kingdom
Language:
English
Other Identifying Numbers:
Journal ID: CODEN: PHMBA
Submitting Site:
HEDB
Size:
Pages: 1319-1331
Announcement Date:

Citation Formats

Harrison, R M, and Day, M J. Theoretical and experimental studies of the influence of air kerma rate on threshold contrast in diagnostic fluoroscopy systems. United Kingdom: N. p., 1983. Web. doi:10.1088/0031-9155/28/11/011.
Harrison, R M, & Day, M J. Theoretical and experimental studies of the influence of air kerma rate on threshold contrast in diagnostic fluoroscopy systems. United Kingdom. doi:10.1088/0031-9155/28/11/011.
Harrison, R M, and Day, M J. 1983. "Theoretical and experimental studies of the influence of air kerma rate on threshold contrast in diagnostic fluoroscopy systems." United Kingdom. doi:10.1088/0031-9155/28/11/011. https://www.osti.gov/servlets/purl/10.1088/0031-9155/28/11/011.
@misc{etde_5028697,
title = {Theoretical and experimental studies of the influence of air kerma rate on threshold contrast in diagnostic fluoroscopy systems}
author = {Harrison, R M, and Day, M J}
abstractNote = {Experimental measurements of threshold contrast (Csub(T)) as a function of air kerma rate at the input plane of the image intensifier have been made for several diagnostic fluoroscopy units in clinical use. Threshold contrasts are determined by viewing a test object containing holes of fixed diameter and various depths under defined irradiation conditions. Kerma rate variations are effected by introducing aluminum sheets into the x-ray beam at fixed values of tube potential and current. At low kerma rates where quantum noise dominates, low tube potentials (60 kVsub(p)) usually yield lower values of Csub(T) than do higher potentials (100 kVsub(p)). At higher kerma rates the opposite is often true. A simple theoretical model for noise propagation in fluoroscopic imaging systems using models of diagnostic x-ray spectra lends qualitative support to the experimental findings. The often-quoted suggested upper limit of 100 ..mu..R s/sup -1/ (0.87 ..mu..Gy s/sup -1/) at the input phosphor would seem to be justified under the test conditions since little improvement in Csub(T) is usually observed at higher kerma rates. However, application to clinical practice would ideally require the use of more realistic phantom studies.}
doi = {10.1088/0031-9155/28/11/011}
journal = {Phys. Med. Biol.; (United Kingdom)}
volume = {28:11}
journal type = {AC}
place = {United Kingdom}
year = {1983}
month = {Nov}
}