Feature | September 03, 2008| Maureen Leahy-Patano

Flat Panel Detectors Lower the Dose

FPD technology boasts a host of benefits, not the least of which is reduced radiation dose.

Angiography systems have been a diagnostic mainstay in cardiac cath labs for more than 50 years, playing a pivotal role in the diagnosis and treatment of heart and vascular diseases. Replacing imaging intensifiers with flat panel detectors (FPD) for angiography has broadened digital imaging’s role in the cath lab. Cardiologists can now see, immediately and with greater clarity, the intricacies of the heart and the vascular system and how well they are functioning.

In addition to improving image quality, FPD systems bring another benefit to the cath lab — a reduction in X-ray dose to the patient and the people in the room.

“The most important feature to cardiologists who perform a lot of procedures every day is the reduction in radiation dose,” said Anjan Gupta, M.D., FACC, FSCAI, cath lab director at Aurora St. Luke’s Medical Center, Milwaukee, WI.

Aurora St. Luke’s is a high volume institution that employs about 80 staff cardiologists and performs 8,000 to 9,000 cath procedures each year. Cath lab services at the facility span the entire gamut of coronary interventional procedures and peripheral vascular interventionals, says Dr. Gupta.

FPD’s reduction in radiation dose — about 20 to 30 percent, estimates Dr. Gupta — along with better image quality and easier storage have made a significant impact on Aurora St. Luke’s cath lab workflow, he says. The types of cases performed in the cath lab have increased; they now perform aortic abdominal aneurysm (AAA) stenting, carotid stenting and other procedures that had been too difficult to perform with the old technology.

FPD technology is easier to work with — and around. The less bulky alternative to image intensifier systems contributes to a smoother flow in the cath lab, while also being easier to maintain.

“We see a lot less technical problems with flat panel detectors. Often the image intensifier systems would break down in the middle of a case. With the newer technology, we rarely have a problem in the middle of a case,” Dr. Gupta explained.
“FPD technology is also bringing other specialists into the cath lab, such as interventional radiologists and cardiothoracic surgeons,” added Dr. Gupta.

Four of Aurora St. Luke’s nine cath labs, including its bi-plane lab, employ GE Healthcare’s Innova FPD technology.

Qualifying the Claims

Through the use of FPD technology, the number of steps required to produce an image is significantly reduced, reportedly resulting in less spatial distortion, improved image clarity and contrast and better dose efficiency.

Putting these claims to the test, researchers Hatakeyama, et al, from the University of Occupational and Environmental Health School of Medicine’s department of radiology, Kitakyushu, Japan, used a vascular phantom to compare the image quality of 2D digital subtraction angiography (DSA) under dose reduction in a FPD system versus a conventional image intensifier-TV system. Results from the seven radiologists’ 171 observations led them to conclude that the FPD system allows a considerable dose reduction during 2D DSA — without loss of image quality.

A number of other radiologist-performed studies also point to a reduction in radiation dose with FPDs when compared to image intensifiers, says Dr. Gupta.

Jon R. Resar, M.D., associate professor of medicine/cardiology, director, adult cardiac catheterization laboratory and director, interventional cardiology at Johns Hopkins Hospital in Baltimore, MD, admits FPD technology has brought about increased consciousness regarding reduced radiation exposure and dosing, yet remains skeptical.

“I am not convinced that flat panel detector technology actually reduces radiation exposure,” Dr. Resar said, adding it is image quality that clearly sets flat panel detector systems apart from image intensifiers.

He cites a recent ACC abstract where Australian researchers examined radiation exposure pre- and post-FPD technology. Interestingly he says, according to the study, radiation exposure was actually greater with FPD technology than with conventional image intensifier technology.

So what is the take-away for cath labs?

“I believe hospital radiation safety personnel need to perform very thorough measurements of radiation exposure for the equipment when it is first sited rather than relying on vendor claims alone,” advised Dr. Resar.

The dose debate aside, one thing is certain: FPD systems are driving the transformation of the cath lab from a pure cardiology center to a multidisciplinary care area where cardiologists, interventional radiologists, vascular surgeons and other specialists can practice.

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