Distributions of scatter-to-primary and signal-to-noise ratios per pixel in digital chest imaging.
The aim of this work was to calculate distributions of scatter-to-primary ratios (epsilon(s)/epsilon(p)) and signal-to-noise ratios per pixel (SNRp) in chest images. Such distributions may provide useful information on how physical image quality (contrast, SNR) is distributed over the posterior/anterior (PA) chest image. A Monte Carlo computer program was used for the calculations, including a model of both the patient (voxel phantom) and the imaging system (X-ray tube, anti-scatter grid and image detector). The calculations were performed for three PA thicknesses 20, 24 and 28 cm. For a 24 cm patient, the epsilon(s)/epsilon(p) varies between 0.5 in the lung to 2.5 behind the spine and heart. The corresponding variation of the SNRp is a factor of 3, with the highest values in the lung. Increasing the patient thickness from 20 to 28 cm increases the epsilon(s)/epsilon(p) by a factor of 2.2 behind the spine and heart.
Ullman
Gustaf
G
Department of Radiation Physics, Linköping University, SE-581 85 Linköping, Sweden. gusul@imv.liu.se
Sandborg
Michael
M
Dance
David R
DR
Hunt
Roger
R
Alm Carlsson
Gudrun
G
D003201:Computers; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008168:Lung / Q000000981:diagnostic imaging; D009010:Monte Carlo Method; D019047:Phantoms, Imaging; D011829:Radiation Dosage; D011856:Radiographic Image Enhancement / Q000379:methods; D013902:Radiography, Thoracic / Q000295:instrumentation* / Q000379:methods*; D012542:Scattering, Radiation; D012984:Software; D013679:Technology, Radiologic / Q000379:methods*