The quality control of liquid-crystal display (LCD) monitors has become one of the important topics for maintaining reliable soft-copy readings in the interpretation of diagnostic images. In this paper, the effects of correction in the luminance measurement of an LCD monitor by use of a telescopic-type luminance meter were investigated. The luminance of the LCD monitor in different ambient-lighting conditions was measured and compared to the results obtained with no ambient lighting (0 lux). The reproducibility of luminance measurements and luminance ratios without a baffled tube was lower than those measured with the baffled tube due to the effect of ambient light. These tendencies were obvious at a relatively low luminance. The correction method by subtraction of the reflected ambient light on the surface of the LCD monitor and the stray light of the telescopic-type luminance meter from the measured luminance was examined. We found that the correction was able to bring the luminance close to that measured with the baffled tube.
Background SwiftScan single-photon emission computed tomography (SPECT) is a recently released scanning technique with data acquired when the detector is stationary and when it moves from one view to the next. The influence of scan time for using SwiftScan on quantitative bone SPECT remains unclear. This study aimed to clarify the effect of the scan time for SwiftScan SPECT on the image quality and quantification of bone SPECT compared to step and shoot mode (SSM) using 99mTc-filled anthropomorphic phantom (SIM2 bone phantom). Materials and methods Phantom SPECT/computed tomography (CT) images were acquired using Discovery NM/CT 860 (GE Healthcare) with a low-energy high-resolution sensitivity collimator. We used the fixed parameters (subsets 10 and iterations 5) for reconstruction. The coefficient of variation (CV), contrast-to-noise ratio (CNR), full width at half maximum (FWHM), and quantitative value of SwiftScan SPECT and SSM were compared at various acquisition times (5, 7, 17, and 32 min). Results In the short-time scan (< 7 min), the CV and CNR of SwiftScan SPECT were better than those of SSM, whereas in the longtime scan (> 17 min), the CV and CNR of SwiftScan SPECT were similar to those of SSM. The FWHMs for SwiftScan SPECT (13.6–14.8 mm) and SSM (13.5–14.4 mm) were similar. The mean absolute errors of quantitative values at 5, 7, 17, and 32 min were 38.8, 38.4, 48.8, and 48.1, respectively, for SwiftScan SPECT and 41.8, 40.8%, 47.2, and 49.8, respectively, for SSM. Conclusions SwiftScan on quantitative bone SPECT provides improved image quality in the short-time scan with quantification similar to or better than SSM. Therefore, in clinical settings, using SwiftScan SPECT instead of the SSM scan protocol in the short-time scan might provide higher-quality diagnostic images than SSM. Our results could provide vital information on the use of SwiftScan SPECT.
Background: SwiftScan (GE Healthcare) is a recently developed scanning technique with data acquisition during detector static and rotation. The influence of image quality using SwiftScan on quantitative bone single-photon emission computed tomography (SPECT) remains unclear. This study clarifies the effect of the acquisition time for SwiftScan on the image quality and quantification of bone SPECT compared to step and shoot mode (SSM) using 99mTc-filled anthropomorphic phantom (SIM2 bone phantom).Results: The coefficient of variance (CV), contrast-to-noise ratio (CNR), full width at half maximum (FWHM), and recovery coefficient (RC) of SwiftScan and SSM were recorded at various overall acquisition times (5, 7, 17, and 32 min) when the fixed reconstruction parameters (subsets 10 and iterations 5) were compared. The CV of SSM was higher than that of SwiftScan in short-time acquisition (less than 7 min), whereas the CV of SSM and SwiftScan are equivocal in long-time acquisition (more than 17 min). The CNR of SwiftScan was higher than that of SSM in short-time acquisition, whereas the CNR of SSM was equivocal or higher than that of SwiftScan in long-time acquisition. The FWHM of SSM (15.2–16.5 mm) and SwiftScan (15.4–15.9 mm) was almost constant when the acquisition time was 7 min or longer. However, SwiftScan (22.6 mm) and SSM (18.6 mm) showed high FWHM values at 5 min acquisition, deviating from the actual size (10 mm). For the RC of SwiftScan and SSM, was no evident difference between them was observed.Conclusions: SwiftScan on quantitative bone SPECT provides improved CV and CNR in short-time acquisition (less than 7 min) with quantitativeness similar to SSM. Therefore, using SwiftScan in clinical settings instead of the SSM scan protocol in short-time acquisition (less than 7 min) might provide higher quality diagnostic images than SSM. Our results would provide important information on the use of SwiftScan.
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