Dose reduction in DSCT compared to 64-MDCT

Abrar Hayat, Kuwait, has sent the following question:

dose reduction in DSCT compared to 64-MDCT:
Other venders claim that they have upgraded their 64-MDCT with new applications so that the dose is reduced by 50 % compared to their regular 64-MDCT! how does the DSCT compare to those? Am I going to significantly reduce the patient’s dose if i use DSCT? What about the 2 tubes in DSCT, moving at such a high speed with the issue of centrifugal force. From your experience, is thee any trouble of that sort?

Sebastian Leschka, M.D., University Hospital Zurich:

Theoretically in DSCT running of two x-ray tubes at the same time should increase the radiation dose compared to that of a single source system. However, several – in our clinical experience very effective – dose reduction techniques have been implemented in the DSCT system including an optimized cardio bowtie filter which avoids unnecessary radiation exposure of extracardiac structures, adaptation of pitch values to the heart rate, and an advanced tube current modulation with free selectable ECG pulsing window width.
In particular, the heart rate-adapted pitch values and the advanced ECG pulsing are effective in reducing the radiation dose particularly in patients with high heart rates. Comparing the DSCT with a single source 64-section row CT, the radiation dose is reduced from approximately 12-21 mSv (64-section CT) to 7-9 mSv (DSCT) when phase synchronization is performed by retrospective ECG triggering. Further dose reduction techniques in normal weight patients (ie imaging at low tube voltage and tube current) and low heart rate (ie prospective ECG gating) permits CT coronary angiography to be performed at a radiation dose of 1-3 mSv.
Answering to the second part of your question: Albeit there is a high mechanical force in DSCT (eg around 28 G for 330 msec rotation time), we have performed more than 1500 cardiac DSCT studies so far and did not observe any problems with that.

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