Relationship between size-specific dose estimates and image quality in coronary computed tomography angiography depending on tube voltage and scan field of view.

BACKGROUND

Advances in computed tomography (CT) technology have driven rapid development in cardiac applications, and achieving a balance between image quality and radiation dose has become a current research focus. This study aimed to quantitatively evaluate the effects of tube voltage and scan field of view (SFOV) selection on image quality and radiation dose in coronary CT angiography (CCTA), and analyze gender differences, thereby facilitating the development of personalized scanning protocols for patients.

METHODS

A total of 120 patients who underwent CCTA examinations on a 256-row CT scanner were retrospectively included and divided into eight subgroups based on tube voltage, SFOV, and gender. Patients' axial images were collected, with volume CT dose index (CTDIvol) values extracted from dose reports. Axial size-specific dose estimation (SSDEz) of the patients was calculated based on axial CT images or CT localizer radiographs, and the region of interest (ROI) was placed on the target sections of vessels to determine objective evaluation of image quality. First, we analyzed the differences in radiation dose metrics (CTDIvol, SSDEz) between genders under varying tube voltages (120 and 100 kV) and SFOV (large SFOV and small SFOV) settings. Second, we explored the impact of these parameter settings on objective image quality. Finally, we used linear regression fitting to evaluate the correlation between radiation dose metrics and objective image quality indicators.

RESULTS

Under different tube voltage and SFOV settings, both CTDIvol and SSDEz were higher in female patients than in males. The difference in the latter metric was statistically significant, with P values of 0.031 and 0.047, respectively. SSDEz in different tube voltage groups and SFOV groups were 29% and 49% higher than CTDIvol. A parameter choice of 100 kV and small SFOV generally showed better image quality, and the correlation between SSDEz and signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) was stronger.

CONCLUSIONS

Due to differences in tissue structure, female patients receive a higher radiation dose during CCTA. The CTDIvol underestimates the patient dose, and it is recommended to use the SSDEz assessment. On the premise of ensuring no omission of lesions, it is advisable to use parameter scanning with 100 kV and small SFOV for superior image quality.