Optimizing Radiation Dose Of Coronary Artery Imaging With Multi-detector Computed Tomography

ObjectiveTo optimize radiation dose of coronary artery imaging with Multi-detector Computed TomographyMaterials and methods200 patients were included in the study ,and all the CT examinations were performed using a 256-detector row scanner (Brilliance iCT, PHILIPS).according to standard position before the scan placed onoff condition, we administered 0.5mg of sublingual nitroglycerin to all the subjects for coronary vasodilation 3 minutes before the scanning. We injected 1ml/kg of a noniodine contrast medium (Ultravist 370; Schering, Berlin, Germany) into an antecubital vein and this was followed by 30-40 mL of normal saline, both at a flow rate of 4-6 mL/sec. A bolus triggering method was used to determine the beginning of CT acquisition by monitoring the signal density of the contrast medium in the midascending aorta. The CT scans were started 7 seconds after a threshold trigger of 110 Hounsfield unit (HU) above the baseline was reached. Minimizing the voltage and current, adjusting Z axis scanning scope, increasing pitch, ECGmA modulation method and prospective electrocardiograph (ECG)-triggered axial scan are evaluated in our study. Our study focus on the ECGmA modulation method and prospective electrocardiograph (ECG)-triggered axial scan. ResultsMinimizing the voltage can obviously reduce radiation dose, but applies only to children and lower BMI patients; according to the BMI minimizing tube current can obviously reduce radiation doses;Operators strictly control the Z axis scanning range can decrease the radiation dose。If effective mAs fixed ,the pitch increased will lead to the mA increased,and the total radiation dose remain unchanged. the ECGmA modulation method and prospective electrocardiograph (ECG)-triggered axial scan effectively reduce the radiation dose. prospective electrocardiograph (ECG)-triggered axial scan can reduce the radiation dose for the majority of patients who have different heart rate and image quality remain unchanged.ConclusionWhen the Operator can according to individual circumstance indiidual the scan and using all the minimizing radiation dose methods,MDCT coronary artery imaging radiation dose can obviously reduce.