Asian Journal of Medical Principles and Clinical Practice

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

Ezinma Helen O.

Department of Radiology, University College Hospital, Ibadan, Oyo State, Nigeria.

Owoade Latifat R. *

National Institute of Radiation Protection and Research, Nigerian Nuclear Regulatory Authority, University of Ibadan, Nigeria.

*Author to whom correspondence should be addressed.

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Abstract

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 (CTDI_vol) and Dose Length Product (DLP) with scan acquisition parameters in other to establish the Correlation of CTDI_vol 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 CTDI_vol and Total DLP.

Results: The Total CTDI_vol 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 CTDI_vol 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 CTDI_vol 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.  CTDI_vol 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 CTDI_vol and DLP in Cranial and Abdomino-pelvic CT.

Conclusion: The relationships between CTDI_vol 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 CTDI_vol and DLP in both investigations.

Keywords: Computed tomography, correlation, Volume Computed Tomography Dose Index (CTDIvol.), Dose Length Product (DLP), Abdomino-pelvic CT scans

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