Analysis of image quality and radiation dose in routine adult brain helical and wide-volume computed tomography procedures.

Objectives: To evaluate and compare image quality and radiation dose between the helical and wide-volume scans to determine the protocol that provides a lower radiation dose without loss in image quality.

Methods: The study was prospectively conducted on consented adult patients that presented for routine brain CT. Image quality and radiation dose were compared between the helical and wide-volume scans on the Toshiba 160-slice Aquilion Prime CT scanner. The volume computed tomography dose index (CTDIvol) and dose length product (DLP) for each scan mode were collected and compared. Image quality was quantitatively and qualitatively evaluated using the unenhanced brain CT images. The data were analysed using a statistical package for social sciences (SPSS) software version 20 for both the descriptive and inferential statistics. A significant difference in image quality and radiation dose between the helical and wide-volume scans was determined based on a p-value of <0.05.

Results: A total of 54 participants were included, with two groups of 27 participants. The CTDI and DLP values were significantly p < 0.05 higher in the helical scan (CTDI: 65 mGy; DLP: 1597 mGy.cm) compared to the wide-volume scan (CTDI: 54 mGy; DLP: 1133 mGy.cm). The grey and white matters show a better signal-to-noise ratio (SNR) for the helical scan. Meanwhile, the contrast-to-noise ratio (CNR) was significantly p < 0.05 higher in the wide-volume scan. The results from the visual grading methods were compared and showed superior image quality in helical over the wide-volume scan.

Conclusion: Wide-volume provides a lower dose compared to helical and therefore, could be adopted as the routine protocol for brain CT for in house dose optimisation. Where clinical conditions warrant the need for a helical scan, the protocol should be optimised in line with the as low as reasonable achievable (ALARA) principle.