Chulalongkorn Medical Journal


Background : The 320- detector row CT scanner with a larger z-coverage (16 cm)competently enables whole brain imaging that is need for patientswho are been requested for comprehensive stroke imaging withaxial volume mode which exposes the patient to a relatively highdose of radiation.Objective : The purpose of the study is to determine the radiation dose on wholebrain computed tomography in comprehensive stroke imaging usingAxial Volumetric 320-detector MDCT.Designs : Observational retrospective study.Setting : Advanced Diagnostic Imaging Center (AIMC), Ramathibodi Hospital,Bangkok.Material and Method : The collected data include scan parameters and radiation dosesfor CT perfusion of the brain examination in comprehensivestroke imaging using the combo protocol in axial volume mode.The effective dose, E, is determined and compared with other studies.Twenty-one patients, 11males and 10 females, with their age rangeof 6 - 77 years and mean age of 45.4 years were studied.Results : Range of cumulative radiation dose for CTDIvol, DLP and E were142.9 - 313.4 mGy, 2286.6 - 5014.2 mGy.cm and 4.8 - 10.5 mSvrespectively. The cumulative dose, average dose, and averagedose per volume scan of CTDIvol, DLP and E were 200.5, 40.8 and10.7 mGy; 3206.8, 652.6 and 171.3 mGy.cm and 6.7, 1.4, and 0.4mSv consecutively.Conclusions : The high radiation dose in this study resulted from large z-coverageof axial volume mode, high tube current and large number of totalvolume scans. The data were compared with DRLs and other studiesfor the setup of the dose reduction protocols appropriate for variousage and groups of the patients size in future study. Althoughthe high radiation dose is one of the main concerns, this investigationresulted in the elimination of the brain coverage limitation. The lowersettings on scan parameters can reduce the volume of the contrastmedia and the acquisition time.


Faculty of Medicine, Chulalongkorn University

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