Reducing radiation exposure is a very important issue in interventional cardiology techniques such as percutaneous coronary intervention. Although novel techniques to reduce radiation exposure are valuable, we should also reconsider older techniques. Digital zoom has been available in Japan from 2005. Digital zoom enlarges an 8-inch field of view (FOV) by 1.2 times, allowing visualization of a 6.7-inch FOV without FOV switching. We identified 2101 suitable cases of percutaneous intervention (PCI) and divided them into two groups according to the use of digital zoom; 1195 patients were included in the digital zoom group and 906 patients in the conventional group. We collected data regarding the reference air kerma (RAK) and dose-area product (DAP). We calculated RAK and DAP per minute fluoroscope time (RAK/min, DAP/min, respectively). There were intergroup differences in RAK, DAP, RAK/min, and DAP/min (digital zoom group vs conventional group; RAK, 1590 mGy [990-2410] vs 1850 [1220-2720], p < 0.01, RAK/min; 54.7 mGy/min [38.5-73.2] vs 71.2 [51.5-93.0], p < 0.01; DAP, 16,000 cGy × cm2 [10,300-24,400] vs 20,700 [13,400-29,500], p < 0.001; DAP/min, 557 cGy × cm2/min [392-737] vs 782 [571-1010], p < 0.01, respectively). Because of baseline differences between the two groups, we performed propensity score matching. Even after score matching, there were intergroup differences in DAP, DAP/min, RAK, and RAK/min. Furthermore, the least squares method showed that digital zoom is a significant predictor of RAK (β = 0.14, p < 0.01) and DAP (β = 0.20, p < 0.01). Digital zoom is an older cost-effective technique that can significantly reduce radiation exposure in PCI.
Keywords: Coronary intervention; Digital zoom; Dose-area product; Radiation dose reduction; Reference air-kerma.