Steve Burion MS, Presenter: Employee, Triple Ring Technologies, Inc

Augustus Lowell, Abstract Co-Author: Employee, Triple Ring Technologies, Inc

Joseph Heanue PhD, Abstract Co-Author: President, Triple Ring Technologies Inc

Edward Solomon, Abstract Co-Author: Employee, Triple Ring Technologies, Inc

Tobias Funk PhD, Abstract Co-Author: Employee, Triple Ring Technologies, Inc

X-ray fluoroscopy is widely used for image guidance during cardiac intervention. However, radiation dose in these procedures can be high and this is a significant concern in pediatric applications; for children the risk of developing cancer from radiation exposure is about 10-fold higher than in adults. We are funded by an NIH Challenge Grant to investigate dose reduction in pediatric imaging and have realized equalization filtration based on the intrinsic properties of our scanning-beam digital X-ray (SBDX) system.

The SBDX system is a fluoroscopic imaging system that employs a novel imaging geometry. Conventional systems use an X-ray tube with a single focal spot and an extended detector. The patient is positioned close to the detector. In contrast, our approach utilizes an extended X-ray source with multiple focal spots focused onto a pixelated detector with the patient positioned far from the detector. Importantly, in our system the final image is not generated from a single detector image as in conventional systems. Rather, it is comprised of 9,000 detector images that are reconstructed in real-time. Equalization filtration utilizes the multibeam scanning technique of SBDX: Rather than exposing every part of the image with the same radiation dose, we can dynamically and automatically vary the exposure depending on the opacity of the region exposed. Thus, we can reduce exposure significantly in translucent areas such as the lung field and maintain exposure in more opaque regions. We have performed experiments with an anthropomorphic phantom with and without equalization filtration at exposure rates of 10 R/min. Dose savings were estimated by comparing the number of detected photons for each method.

Our initial experiments show that by using equalization filtration, a dose reduction of up to 50% is readily achievable. We also find that equalization filtration intrinsically compresses the dynamic range of the images and thereby improves image quality.

Equalization filtration offers a new way to reduce radiation dose in X-ray imaging. Our first phantom experiments are encouraging and further validation is under way.

Given the link between cancer risk and radiation dose, especially in young patients, there is a pressing need to reduce radiation dose in pediatric cardiac interventions.

Burion, S, Lowell, A, Heanue, J, Solomon, E, Funk, T, Real-time Equalization Filtration: Dose Savings with Region-based Exposure Control Using a Scanning Beam X-ray Source.  Radiological Society of North America 2010 Scientific Assembly and Annual Meeting, November 28 - December 3, 2010 ,Chicago IL. http://archive.rsna.org/2010/9008550.html