Cardiac Catheterization: Impact of Face and Neck Shielding on New Estimates of Effective Dose

Abstract

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.

A new method for effective dose calculation based on the ambient dose height distribution

“…From the measured values of H* (10) in height of the breast values for the personal dose H p (10) were derived and compared with the calculated values of E (see Table 4). …”

“…No additional radiation protection equipment like ceiling mounted shields were used, since these are used very unfrequently. The values of H* (10) were measured in steps of 10 mm. The used coefficients calculated with the model to determine E are given in tabular form in Table 2, the results are shown in Table 3.…”

“…The model is very useful not only to estimate E in a predetermined radiation protection situation and to correct inaccuracies of the personal dosimetry but also to optimize the staff radiation protection by minimizing the effective dose [10].…”

“…In radiation protective practice, it is usually estimated based on individual measurements of the personal dose. If H p (10) is measured with a single dosimeter underneath the protective apron (the standard in Germany) the effective dose is underestimated in many situations. In fact a monthly dose value "zero" is often indicated.…”

Endovascular Repair: Radiation Risks

“…However replacement has to be carried out at an earlier stage, if the unprotected area over testes and the thyroid exceeds 0.2 and 0.1 cm 2 , respectively. Aprons with 0.5 mm nominal Pb equivalent thickness reduce staff effective dose by a factor of about eight, when an 87 kilovolatge is selected (von Boetticher, et al, 2009). Higher kV, such as those used on obese patients, sharply reduces the shielding benefit.…”