Grant: Collaborative Health Research Projects

The role of real-time x-ray fluoroscopic imaging is expanding and important for diagnostic, evaluation and image guided interventional applications. In 2010, it is estimated that there were over 3 million cardiac catheterization procedures performed in North America using x-ray fluoroscopy. One of the main reasons for this frequency is the increased prevalence of catheter based therapies. Angioplasty, particularly balloon inflation with the addition of a stent, has markedly improved the success of the procedure by reducing the rate of re-stenosis, allowing for a less invasive treatment of complex lesions that were previously exclusively treated with coronary bypass surgery. Cardiac intervention procedures are quite long and require multiple x-ray exposures to a patient. As a result, the radiation dose from a single interventional fluoroscopic procedure canbe 1-10 times that in CT. It has been recognized that this is unacceptable and must be reduced.The x-ray fovea or the region of interest method (ROI) has been identified as a means of reducing this dose but it has not yet been clinically implemented by the major manufacturers. The ROI method is based on the realization that the eye of an interventional physician can only see a small region of the image with high resolution, because it is limited by the human eye's fovea size. Peripheral vision is needed to maintain context. However, it is not necessary to provide a high quality image in the peripheral region for the eye-brain system to process the image. Thus, there is a huge potential for reduction of exposure to a patient if only the ROI actively being viewed by the physician is of high quality (i.e., refreshed at the real-time rate and full exposure level). The exposure to the peripheral area can be minimized by reducing dose rates without the observer being aware of this loss.