Cardiac catheterization: impact of face and neck shielding on new estimates of effective dose.

Optimization of radiation protection devices for the operator is achieved by minimizing the effective dose (E) on the basis of the recommendations of Publications 60 and 103 of the International Commission on Radiological Protection (ICRP). Radiation exposure dosimetry was performed with thermoluminescence dosimeters using one Alderson phantom in the patient position and a second one in the typical position of the operator. Various types of protective clothing as well as fixed leaded shieldings (table mounted shielding and overhead suspended shields) were considered calculating E. Shielding factors for protective equipment can readily be misinterpreted referring to the reduction of the effective dose because fixed protective barriers as well as radiation protection clothing are shielding only parts of the body. With the ICRP 103 approach relative to the exposure without lead protection, a lead apron of 0.35 or 0.5 mm thickness reduces E to 14.4 or 12.3%, respectively; by using an additional thyroid collar, these values are reduced to 9.7 or 7.5%. A thyroid collar reduces the effective dose by more than an increase of the lead equivalency of the existing apron. Wearing an apron of 0.5 mm lead-equivalent with a thyroid collar and using an additional side shield, E decreases to 6.8%. Using both a fixed side and face shield decreases E to 2.0%. For protective garments including thyroid protection, the values of the effective dose in cardiac catheterization are 47-106% higher with ICRP 103 than with ICRP 60 recommendations. This is essentially caused by the introduction of new factors for organs in the head and neck region in ICRP 103.