Get fighting RAD (radiology against dose)!

December 5, 2008

Concerns about CT dose that took root in Europe have emigrated to the U.S. With both sides of the Atlantic involved, vendors have launched an all-out war to reduce patient dose. One of the latest developments is the Definition Flash, which, according to its developer, Siemens, can cut dose for a high-resolution scan of the coronaries to less than the annual accumulated dose from naturally occurring background radiation.

Concerns about CT dose that took root in Europe have emigrated to the U.S. With both sides of the Atlantic involved, vendors have launched an all-out war to reduce patient dose. One of the latest developments is the Definition Flash, which, according to its developer, Siemens, can cut dose for a high-resolution scan of the coronaries to less than the annual accumulated dose from naturally occurring background radiation.

Siemens is neither the only nor even the first vendor to make gains against patient dose. GE, Philips, and Toshiba have introduced noteworthy technologies over the last several years aimed at cutting x-ray exposure. What stands out with the Definition Flash is the emphasis that Siemens has put on cutting dose.

At the scanner's official unveiling on the RSNA exhibit floor, the company gave dose reduction equal billing with speed, which for the past decade has had the marquee all to itself.

Rank this revolution along with those to gain public acceptance of the seat belt, bans on smoking, and litter-free highways. And, like these other revolutions in thinking, successes in cutting patient dose were not achieved with a single magic bullet. Rather, they involved a multifaceted effort that includes shutters to block excess x-rays, improved detectors, electronics to clean up x-ray beams, and software to adjust these beams during the scan. One of those adjustments is to simply turn off the beam when it's not needed.

It's the same idea behind pulsed fluoro and last-image hold, an innovation whose simplicity is overshadowed only by its clinical value, which was demonstrated during millions of interventions. CT is a far more sophisticated modality that demands more sophisticated answers. But they are being found. The question is, how far can these solutions reach?

Much of the progress against dose has been achieved on high-end systems, arguably the easiest technological venue on which to work, as new platforms can be designed to incorporate dose savings. The problem is that older platforms, notably 16- and 64-slice CTs, make up the bulk of new unit sales each year. These radiological workhorses will continue to function well into the future.

Enhancements built into mid- and low-tier production line units are a step in the right direction, but the industry can't stop even there. The life cycle of thousands of CT scanners now operating in the U.S. is stretching from four or five years to six or seven. Field upgrades that cut dose will be critically important to the health of the nation in the coming years.

Also, vendors other than just the big four must look into dose savings. The last several years have seen a spate of niche CTs enter the market, some for specialty medical applications, others for dental applications. These systems are designed for use by professionals other than radiologists, who may not have the same concerns about patient dose.

It is in the broader arenas of CT use that the radiology community and the leading manufacturers of CTs must also push for progress against excess dose. In the same way proponents of seat belts, no smoking, and a litter-free world agitated for their ideas to be adopted, so must we expand our efforts to cut patient x-ray dose anywhere it is found.

The achievements that took center stage last week on the RSNA exhibit floor indicate that amazing things can be done to reduce dose. There are still, unfortunately, a lot of amazing things left to do.