Siemens Definition - DSCT - dual source CT - first review article

This is the first of two articles published this quarter on DSCT (the Siemens Definition Dual Source CT) in European radiology journals (the second article is discussed here). This article by Flohr et al in the Feb 2006 issue of European Radiology explores the physics behind the dual-source CT. In brief, there are two tubes and gantries at 90degrees to each other rotating at 330ms. The use of this dual-tube technology allows a temporal resolution of 83ms and with two-segment reconstruction, 42ms. Apparently, we do not need to use beta-blockers, since we can scan at pretty much any heart-rate.

With single-source scanners, we reach a temporal resolution of 83ms at heart rates of 66, 81 and 104, whereas with a DSCT scanner, this resolution is reached at any heart rate.

The big advantage of course, seems to be the ability to scan at any heart rate without pre-preparing with beta-blockers. Practically, this means that patients need not have to wait and can be taken into the scanner with just 4 hours of fasting, making a cardiac CT study a routine study.

Below are two images of the RCA (Fig. 1) and LAD (Fig. 2) showing the vessels at 25% and 70% reconstruction, though the heart rate has not been specified. These images have been obtained from the press release area of the Siemens Dual-Source site, where they have been released for press use.

Comments

[Marcelo Hadlich]

The images of the Siemens DSCT is very good, and I was reading that the radiation is not 2 times of the conventional 64 ct. How come they get this ?

[J Stan]

Supposedly radiation dose is not 2X normal dose...but I think this is some sneaky marketing by Siemens. They even try to claim that it's 1/2 the dose...that's bold. But they make the comparison to older systems without ECG-dose modulation and filters -- which nearly every new system has had for the past 2 years. Xrays scattered in the body from one tube onto the other detector would actually necessitate a dose increase if you want to get the same noise level in your images.