Skip to main content

MGH Customizes CT Radiation Doses via 'Virtual Autopsy'

 |  By cclark@healthleadersmedia.com  
   June 01, 2011

Using cadavers, researchers at Massachusetts General Hospital are testing and customizing CT protocols to dramatically cut the dosage needed for live patients by as much as half the reference levels nationally.

"We have to ask the question, have all providers of imaging services that use radiation optimized their protocols? We realized that very sadly, the answer to that is no, they have not," said radiologist-in-chief James H. Thrall, MD, who founded the MGH Webster Center, which grew out of a decade's worth of radiation dose research efforts at MGH.

In part because of recent accidents such as the overdose of more than 200 brain perfusion patients at Cedars Sinai Medical Center in 2009, and other well-publicized CT miscalculation errors, and the Biological Effects of Ionizing Radiation report from the National Academy of Sciences, physicians need to be more cautious about radiation. They should use just that which is necessary to get an image that's good enough for diagnosis, Thrall says.

"A lot of radiologists value very high quality images, and a lot of radiologists have the orientation that the best image you can get is what you should try to get," he says. "They try to make images that look very, very pretty, instead of making images that are good enough.

"Well, in retrospect, we realized that we don't need to get the best image to give an accurate diagnosis," he says.

Through the Webster Center,  launched last September with a $750,000 grant from the late Edward (Ted) Webster, an educator and scientist with the MGH's Department of Radiology, MGH is publishing a variety of protocols for imaging various parts of the body.

Doses are customized for men and women, for certain age brackets and weights, and for other variables for which minimal radiation doses are unclear. So far, protocols cover abdominal, cardiac, chest, musculoskeletal, neurological and pediatric exams. More types of imaging screens will come.

Thrall says that imaging technology is not a one-dose fits all, although that may have been how it was formerly applied.

Five or so years ago when the first 64-slice CT scans came out, he acknowledges, there was a rush to scan and a somewhat cavalier attitude on the part of providers over the impacts accumulated doses might have evolved.

Now that is being dramatically reversed, he says.

So far, he and other researchers have used dose threshold techniques on about 40 cadavers in what Thrall calls "a virtual autopsy."

"As cadavers become available, we image them in the CT suite, starting at very, very low doses, and then at increasingly higher doses until we get up to a dose above what we would use clinically. And from this data, we can further optimize the amount of radiation we give to patients."

He adds that technology is evolving so rapidly, there isn't the opportunity to perform dose-ranging studies in living patients.

"Rather than do the scan and realize you didn't use enough, the tendency has been to use more than enough to make sure you get a good image. But by having cadavers with different sizes we can really focus on the absolutely lowest dose that will be diagnostically acceptable."

Progress in reducing doses has been rapid. "A few years ago, a CT scan would be about 20-30 millisieverts," he says. "Today, if you were to come to most departments with the next generation of equipment, you'd get maybe two-to three, a factor of 10 reduction. That's the kind of progress we're making," he says.

Plans are underway to use various manufacturers' scanning technology to refine the effort, to customize it even further for various parts of the body, for a variety of brands of equipment.

In a statement announcing the new protocols, Dushyant V. Sahani, MD, director of CT Imaging at MGH, noted that "CT dose is a moving target, so we will continue to invest in new technology, research, and education to meet our obligations to our patients."

See Also:
CA Governor Signs Radiation Overdose Bill into Law
Doctors Need Decision Support in Ordering Imaging Diagnostics
Radiation Patients Endanger Public, Congressman Says

Tagged Under:


Get the latest on healthcare leadership in your inbox.