Relationships between entrance skin dose, effective dose and dose area product for patients in diagnostic and interventional cardiac procedures

Skin injuries have recently been reported for patients in diagnostic and interventional cardiac procedures. Cardiac catheterisation equipment usually has dose monitors showing the dose-area product (DAP) but the DAP value alone is not a suitable indicator for skin dose since the projections vary during the procedures. This work deals with measurements of maximum entrance skin dose, MESD, and effective dose, E, to an anthropomorphic phantom using TL dosemeters placed both on the outside of and inserted in the phantom and simulating a diagnostic and an interventional clinical procedure. DAP Values were used for calculating conversion factors: MESD/DAP was 3.8 and 8.1 mSv.Gy(-1).cm(-2) and E/DAP was 0.23 and 0.26 mSv.Gy(-1).cm(-2) for diagnostic and interventional procedures respectively. Maximum permissible DAP value for preventing skin damage, i.e. MESD <2 Sv, is therefore 530 and 250 Gy.cm(-2) respectively for diagnostic and interventional procedures. These results should be used as a local reference level for the patient dose to prevent skin burden. Patient mean DAP was 73, 120 and 170 Gy.cm(2) and effective dose 16, 31 and 41 mSv for diagnostic, interventional and combined procedures respectively.