Objective:To assess the impacts of abdominal spectral computed tomography (CT) scans on radiation dose in order to validate the feasibility of low-dose spectral CT imaging.Methods:Using varying scanning protocols on the Discovery CT750 HD device, the abdomen of an adult male dose-specific phantom was scanned in two modes: conventional single-energy CT (SECT) and gemstone spectral imaging (GSI). Specifically, the conventional SECT mode featured tube voltages of 120 and 80 kVp, automatic tube current modulation technology, and a noise index (NI) of 10 HU. In contrast, the GSI mode was characterized by the automatic spectral imaging protocol selection (ASIS) technique, rapid switching of the tube voltage between 80 and 140 kVp, and Nis for non-spectral scanning of 8, 10, 15, and 20 HU. Then, various radiation dose metrics and objective image quality were compared across different scanning protocols.Results:In the case of the same NI, the three scanning dose modes (SECT with tube voltages of 120 and 80 kVp, and GSI with a tube voltage of 80/140 kVp) presented similar volume CT dose index (CTDI vol) and dose length product (DLP). However, the SECT with a tube voltage of 80 kVp showed the lowest measured organ absorbed dose ( DT; 5.89 mSv). Effective dose ( E) was determined using DLP and organ DT. The result indicated that, under the three modes except for SECT with a tube voltage of 80 kVp, the E values calculated using DLP were lower than those determinized using the organ DT, with deviations ranging from 9% to 20%. The differences in image noise levels and signal-to-noise ratios (SNR) of the three scanning modes were statistically significant ( F = 65.52, 35.09, P < 0.001). Conclusions:Spectral CT using ASIS technology can achieve low-dose spectral scanning while ensuring image quality.

Objective:To assess the impacts of abdominal spectral computed tomography (CT) scans on radiation dose in order to validate the feasibility of low-dose spectral CT imaging.Methods:Using varying scanning protocols on the Discovery CT750 HD device, the abdomen of an adult male dose-specific phantom was scanned in two modes: conventional single-energy CT (SECT) and gemstone spectral imaging (GSI). Specifically, the conventional SECT mode featured tube voltages of 120 and 80 kVp, automatic tube current modulation technology, and a noise index (NI) of 10 HU. In contrast, the GSI mode was characterized by the automatic spectral imaging protocol selection (ASIS) technique, rapid switching of the tube voltage between 80 and 140 kVp, and Nis for non-spectral scanning of 8, 10, 15, and 20 HU. Then, various radiation dose metrics and objective image quality were compared across different scanning protocols.Results:In the case of the same NI, the three scanning dose modes (SECT with tube voltages of 120 and 80 kVp, and GSI with a tube voltage of 80/140 kVp) presented similar volume CT dose index (CTDI vol) and dose length product (DLP). However, the SECT with a tube voltage of 80 kVp showed the lowest measured organ absorbed dose ( DT; 5.89 mSv). Effective dose ( E) was determined using DLP and organ DT. The result indicated that, under the three modes except for SECT with a tube voltage of 80 kVp, the E values calculated using DLP were lower than those determinized using the organ DT, with deviations ranging from 9% to 20%. The differences in image noise levels and signal-to-noise ratios (SNR) of the three scanning modes were statistically significant ( F = 65.52, 35.09, P < 0.001). Conclusions:Spectral CT using ASIS technology can achieve low-dose spectral scanning while ensuring image quality.

Objective:To explore the effects of different scan modes and detector widths on image quality and radiation dose in a wide-body detector CT scanner using phantoms.Methods:A 320-row CT scanner was used to scan Catphan500 CTP404 and CTP486 modules under different scan modes, during which each module was positioned in the center of the scanning field. On the axial scan, the detector collimating width options of 80, 120, 140, and 160 mm were applied successively; on the helical scan, the options of 40 and 80 mm were applied. Tube currents of 240 and 100 mAs were used for both scan modes. The imQuest software, which measures spatial resolution by task-based transfer function (TTF) and noise by noise power spectrum (NPS), was used for objective evaluation, and feature data and CTDI vol values of images were recorded. Results:Scan modes had a significant effect on the spatial resolution and noise of images. For spatial resolution, the TTF curve on the axial scan shifted slightly to the right compared with that on the helical scan, suggesting the association between axial scan and higher spatial resolution; for noise, the NPS peak frequency and average spatial frequency revealed a similar noise texture with the two scan modes, but the noise value and the identical area under the NPS curve suggested that axial scan was less noisy. It had 14% less noise, 26% less area under the curve, better image quality, and about 13% less radiation dose on axial scan than those on spiral scan. The detector collimating width had no significant effect on high contrast resolution and noise, but CTDI vol decreased with its increase, and CTDI vol reduced by 9% when it was doubled on the axial scan. Conclusions:Different scanning method have certain effects on image quality and radiation dose, especially scan modes. In clinical practice, it is required to choose an appropriate scanning method based on the scanning sites and diagnostic requirements.