Title :
Evaluation of the effect of reconstructed image pixel size on defect detectability in Tl-201 fan-beam SPECT by an observer performance study
Author :
Gregoriou, G.K. ; Gsui, B.M.W. ; Gullberg, G.T.
Author_Institution :
North Carolina Univ., Chapel Hill, NC, USA
fDate :
8/1/1995 12:00:00 AM
Abstract :
The effect of reconstructed image pixel size in the fan-beam filtered backprojection method in myocardial defect detection was investigated using an observer performance study and receiver operating characteristics (ROC) analysis. A mathematical phantom of the human torso was used to model the anatomy and Thallium-201 (Tl-201) uptake in humans. Realistic projections from the phantom were simulated using a low-energy high resolution fan-beam collimator that incorporated the effects of photon attenuation, spatially varying detector response, scatter, and Poison noise. For a fan-beam collimator with a focal length of 55 cm and with a radius of rotation of 25 cm, the magnification at the center of rotation was two and the maximum magnification in the reconstructed region of interest was three. Myocardial defects were simulated as Gaussian-shaped decreases in Tl-201 uptake distribution. By changing the reconstructed image pixel size, five different classes of reconstructed images resulted, with projection bin width to reconstructed image pixel size (PBIP) ratios of 1, 2, 3, 4, and 5. The results from the observer study indicate that the reconstructed image pixel size has a significant effect on myocardial defect detection in reconstructed Tl-201 SPECT images. Moreover, the study indicated that in order to ensure maximum defect detectability the PBIP ratio should be at least as large as the maximum possible magnification within the reconstructed image array
Keywords :
dosimetry; image reconstruction; single photon emission computed tomography; 25 cm; 55 cm; Gaussian-shaped decreases; Poison noise; ROC analysis; Tl; Tl-201 fan-beam SPECT; defect detectability; fan-beam collimator; focal length; human Tl-201 uptake; human torso; low-energy high resolution fan-beam collimator; mathematical phantom; maximum magnification; myocardial defect detection; observer performance; photon attenuation; projection bin width; receiver operating characteristics; reconstructed image pixel size; rotation radius; scatter; spatially varying detector response; Humans; Image analysis; Image reconstruction; Imaging phantoms; Mathematical model; Myocardium; Optical receivers; Performance analysis; Pixel; Torso;
Journal_Title :
Nuclear Science, IEEE Transactions on