Valvular heart disease—measurement of valve orifice area and quantification of regurgitation

INTRODUCTION According to the most recent National Council on Radiation Protection and Measurements report (1), Americans were exposed to seven times as much ionizing radiation in 2006 than in the early 1980s. While much of this increase is the result of computed tomography (CT) and nuclear imaging, not an insignificant amount occurs in the cardiac catheterization laboratory. The general public has become increasing aware of the potential hazards of ionizing radiation (2). As a consequence, the use of as-low-as-reasonably-achievable (ALARA) has become a mantra for all healthcare providers to more carefully examine the use of medical radiation. A recent review from the American Heart Association Science Advisory committee has further emphasized the importance of paying attention to radiation effects in cardiac imaging (3). In general, the effects of ionizing radiation have been a much greater focus for the radiologist than the cardiologist. This overview will very briefly discuss the manner in which X-ray images are created to better understand the means by which a reduction in X-ray dose may be accomplished. The radiobiology of ionizing radiation will then be addressed to provide some insight into the consequences of X rays on biologic tissue and how the effects can be minimized.