Radiation exposure to patients undergoing percutaneous coronary interventions: are current reference values too high?

Abstract

Purpose: To determine predictors of patient radiation exposure due to percutaneous coronary interventions (PCI) and to compare our results with the "preliminary reference levels", recently proposed by the European DIMOND research cardiology group: i. e., 75 Gy.cm(2) for dose area kerma product (DAP), 17 min for fluoroscopy time (T(F)), and 1,300 for cinegraphic frames (F).

Material and methods: For 642 PCI-exclusive of the fraction for diagnostic catheterization to avoid statistical confounder effects-we measured total DAP, cinegraphic (DAP(C)) and fluoroscopic (DAP(F)) fractions, the number of cinegraphic frames and runs, and T(F). DAP(C)/F and DAP(F)/s were calculated to indicate the quality of focusing to the region of interest.

Results: The mean total patient DAP for elective one-, two-, and three-vessel PCI amounted to 6.7, 11.6, and 19.4 Gy.cm(2), for PCI of focal in-stent restenoses to 4.2 Gy.cm(2), and for excimer laser angioplasty of diffuse in-stent restenoses to 19.4 Gy.cm(2), respectively. Recanalization of chronic occlusions and PCI in acute myocardial infarction occasioned mean levels of 16.0 and 17.3 Gy.cm(2). Implantation of one and > or = two stents during one-vessel PCI significantly increased total mean DAP from a baseline level of 5.7 up to 7.1 and to 13.8 Gy.cm(2). DAP significantly varied according to the various PCI target regions and amounted to 4.0, 4.5, and 5.5 Gy.cm(2) for intermedius, diagonal, and left anterior descending arteries, to 4.9, 5.0, and 7.0 Gy.cm(2) for obtuse marginal, left posterolateral, and circumflex arteries, to 8.3, 9.1, and 9.5 Gy.cm(2) for proximal/mid right coronary segments, posterior descending, and right posterolateral arteries, and to 11.6 Gy.cm(2) for saphenous vein grafts, respectively.

Conclusion: This study, carried through by consistent use of radiation-reducing techniques, enables a reliable scoring of patient radiation exposure according to complexity and target vessel of the intended PCI. Our 95th percentiles for elective PCI, for recanalizations of chronic occlusions, and for emergency PCI advise reference levels of 22, 32, and 42 Gy.cm(2) for DAP, of 16, 25, and 24 min for T(F), and of 400, 600, and 700 cinegraphic frames, respectively.