Dosimetry of CT-Based Attenuation Correction for Single Photon Emission Computed Tomography/Computed Tomography Examinations

Abstract

The purpose of this study was to determine the radiation dose associated with low-dose CT-based attenuation correction in patients undergoing SPECT/CT examinations. A total of 1055 SPECT/CT examinations consisting of 971 adult patients and 84 paediatric patients were retrospectively reviewed to estimate the effective dose due to low-dose CT scans. The CT radiation dose was estimated by the dose-length product method. More than 60% of adult examinations were skeletal bone scans, while in paediatric examinations, more than 50% were renal scans. The estimated mean effective dose ranged from 0.48 mSv for thyroid scans to more than 8.50 mSv for whole body examinations. The radiation dose resulting from the CT-based attenuation correction is relatively high but is in line with the ranges reported in the literature. Optimisation of CT protocol in SPECT/CT examinations, specifically, the reduction of scanned length (dose-length product) needs to be considered when CT scans of SPECT/CT studies are used only for attenuation correction and localisation.