Correlation of Volume Computed Tomography Dose Index and Dose Length Product with Acquisition Parameters in Abdomino-pelvic and Cranial Computed Tomography Imaging

Introduction: The use of Computed Tomography (CT) in medical diagnosis showing more complex fractures and other pathological findings in 3D, delivers relatively higher radiation doses to patients when compared to conventional X-rays. In order to maintain good diagnosis while reducing patients’ dose, it is necessary to assess the contributions of CT scan acquisition parameters (kV, mAs and scan length) to patient dose, and improve the selection of those parameters. This work aimed at investigating the relationship between the Volume CT Dose Index (CTDIvol) and Dose Length Product (DLP) with scan acquisition parameters in other to establish the Correlation of CTDIvol and DLP with scan acquisition parameters in Abdomino-Pelvic and Cranial CT.

Methodology: A total of 61 existing patients’ data with scan acquisition parameters were collected: Cranial CT (39) and Abdomino-pelvic CT (22). Pearson correlation analysis was used to establish the relationship between scan acquisition parameters and Total CTDIvol and Total DLP.

Results: The Total CTDIvol ranged from 135.6 to 215.5 mGy for cranial CT and 26.1 to 124.4 mGy for Abdomino-pelvic, while DLP ranged from 2631.0 to 6542.8 mGy.cm for cranial and 1147.5 to 5441.8 mGy.cm for Abdomino-pelvic.

The CTDIvol showed moderate positive correlation with kV (r = 0.625, P value ˂ 0.01) for Cranial and strong positive correlation (r = 0.821, P value ˂ 0.01) for Abdomino-pelvic CT, while DLP showed strong positive correlation (r = 0.767 and 0.839, P value ˂ 0.01) for both Cranial and Abdomino-pelvic. The CTDIvol and DLP showed strong positive correlation with mAs (r = 0.843 and 0.839, P value ˂ 0.01) for both cranial and abdomino-pelvic CT. CTDIvol and DLP showed a strong positive correlation with scan length (r= 0.712 and 0.881, P value ˂ 0.001) for both Cranial and Abdomino-pelvic CT. Increase in kV, mAs and scan length may cause significant increase in CTDIvol and DLP in Cranial and Abdomino-pelvic CT.

Conclusion: The relationships between CTDIvol and DLP with scan acquisition parameters in adult patients have been investigated for both Cranial CT and Abdomino-pelvic CT. It was observed that scan acquisition parameters (kV, mAs and Scan length) had linear relationship with CTDIvol and DLP in both investigations.