Estimation of effective dose from CT scanning using dose length product in a Nepalese hospital

Abstract

Keywords: Effective dose, Dose Length Product, Computed Tomography Dose Index
volume, Dose Reference Level

Abstract
Aim: The aim of this study was to estimate the effective doses from CT scans using Dose
Length Product (DLP) in a Nepalese hospital.
Materials and methods: This prospective study was conducted in 150 patients above 18
years of age who were referred for CT scan of head, chest and abdomen. The CT scan was
performed on a 128 slice multi detector scanner. All the subjects who met the inclusion
criteria were included in the study. Following the non-contrast imaging phases of the head,
chest and abdomen CTDIvol, DLP, kVp and pitch were recorded for each patient from the
console display of the scanner. The effective dose was calculated for each examination using
DLP which were graphically analyzed and correlated with the age of the patient.
Results: The study showed the mean CTDIvol for head, chest and abdomen to be 53.95±4.83
mGy, 5.28±1.17 mGy and 11.15±2.71 mGy respectively along with mean DLP to be
923.52±71.11 mGycm, 229.32±48.70 mGycm and 517.02±148.32 mGycm respectively. Using
these values, the mean effective doses were calculated and found to be 1.93±0.14 mSv,
3.20±0.68 mSv and 7.75±2.19 mSv respectively.
Conclusion: The calculated effective dose values were lower than in other studies for CT
examinations of chest and abdomen while higher or similar for CT examination of head. The
results of this survey could motivate other researchers to investigate the radiation doses in
other hospitals and help establish national diagnostic reference levels.