Radiation dose reduction in invasive cardiology by restriction to adequate instead of optimized picture quality.

In this study, the cinegraphic image intensifier entrance dose level for coronary angiography was changed in four steps from dose level A (0.041 microGy frame(-1)), allowing high contrast, but coarse mottled background, to level D (0.164 microGy frame(-1)), affording high transparency and sharpness. Using this new approach throughout the course of 404 consecutive cardiac catheterizations, we reduced patient radiation exposures down to 11 to 16% of currently typical values: i.e., mean dose area products of 5.97 Gy cm2 (n = 91), 6.73 (n = 113), 8.11 (n = 91), and 8.90 (n = 109); cinegraphic dose area products of 2.34, 3.64, 4.56, and 5.49; and cinegraphic dose area products frame(-1) of 13.3, 19.8, 27.0, and 30.2 mGy cm2, for levels A, B, C, and D, respectively. The number of cinegraphic frames ranged within 168 to 182 per case. Our results show that during catheterization interventionalists should vary image intensifier entrance dose levels in accordance with documented structure, angulation, and body mass index. With the exception of cases with special requirements, lower dose levels typically guarantee an adequate image quality.