Abstract 2597: A New Algorithm For ECG-based Tube Current Modulation (``MinDose”) Reduces Radiation Dose Estimates In Cardiac Dual Source CT Angiography
Background: The new dual source CT (DSCT) technology with two X-ray tubes and corresponding detector arrays provides a further improved temporal resolution. All technical advances of modern generations of CT scanners made for improvements of spatial or temporal resolution of cardiac CT angiographies (CTA) are associated with a substantial radiation burden for each patient. Dose saving strategies include a reduced tube current of 100kV and adapted ECG controlled dose pulsing windows (PW). This prospective study analyses the impact of an additionally used new algorithm (``MinDose”), which reduces the tube current from 20% to 4% during the systolic phase of an RR interval. This means that image reconstruction during this phase, which is usually not used for image reconstruction, is impossible due to an insufficient image quality.
Methods: We investigated two consecutive patient populations undergoing cardiac CTA by DSCT (Somatom Definition, Siemens Medical Solutions, Germany) during a 2-month period each. The first group was scanned with a cardiac 100kV protocol and adapted pulsing window, whereas for the second group a 100kV protocol and adapted PW with additionally reduced systolic tube current (``MinDose”) was used. Radiation dose estimates were derived from the dose length product and a conversion coefficient for the chest as investigated body region (k = 0.017 mSv*mGy-1*cm-1). Mean heart rate during the scan as well as administration of betablockers were also reported for each patient.
Results: Detailed scan characteristics, mean heart rate and betablocker amount are shown in table 1⇓.
Conclusions: Patients benefit from this new dose saving tool by an effective reduction of radiation dose estimates for cardiac CT studies of about 30%. A more frequent application of betablockers has to be taken into account to reduce the risk of non evaluable cardiac CT studies due to the fact that additional systolic reconstructions with the new ``MinDose” algorithm are impossible.