Brain Radiation Exposure and Attenuation During Invasive Cardiology Procedures

Overview

Invasive cardiac procedures involve procedural guidance with x-rays in the form of fluoroscopy. X-ray exposure poses a potential risk of acute and long-term complications to staff involved in these procedures. Lead shields are placed between the operators (on their left side) and the x-ray source to limit exposure. However as the operator requires direct access to the patient and x-ray scatter occurs, full protection is not possible. Lead gowns, thyroid collars, and leaded glasses are typically worn to protect the body, thyroid, and eyes respectively, but their thickness is limited by their relatively heavy weight. Nevertheless this leaves the brain exposed. Further, interest in the risk of brain cancer in invasive cardiologists has re-emerged after a recent report of left-sided brain cancer in primary operators of interventional cardiology procedures. Lead caps have been tested in the past but the relatively heavyweight of lead has limited wide-spread implementation. The cap typically worn during invasive procedures is lightweight, has no significant x-ray absorption properties, and is worn to help maintain a sterile environment. A novel, lead-free cap, composed mainly of barium sulfate and bismuth oxide, has been developed that has been shown to absorb x-rays while being significantly lighter than lead. The investigators propose using multiple x-ray detectors to test exposure differences between the primary and secondary operators, the left side and right side of the head, and absorption via a lead-free cap.

This is a prospective study evaluating radiation exposure to operators of invasive cardiovascular procedures at the UCSD Medical Center in La Jolla. Primary and secondary operators of cardiac catheterization procedures using fluoroscopy guidance, including cardiac catheterization, coronary angiography, and interventional procedures will wear multiple dosimeters to evaluate levels of radiation exposure. The primary and secondary operators will wear six dosimeters on their heads; three outside the non-lead attenuating cap and three underneath the cap. Above and beneath the cap, the dosimeters will be on the left side, in the center, and on the right side of the head. The dosimeters will be worn for a target of at least 50 procedures for each operator. The primary operators will be closest to the procedural site and the fluoroscopy unit for the majority of the procedure, while the secondary operators will be to the right side of the primary operators during the procedures. The operators will maintain this designation while participating in the study. All operators will continue to wear the dosimeters issued by the catheterization laboratory as part of standard radiation monitoring. Each operator will be assigned six dosimeters, which will be secured within the cap at the time of assignment. The use of each cap and respective set of dosimeters will be recorded in a log book in the secure cardiac catheterization laboratory and associated with specific cardiac case numbers. Specific factors related to operator radiation exposure for each procedure will be recorded including: operator height, patient weight and BMI, dose area product (DAP), fluoroscopy time, length of procedure, type of procedure, access site, and complexity of procedure as determined by the attending physician. The operators will comment on the comfort of the cap using a semi-quantitative scale and the levels of exposure will be measured from the dosimeters. The operators will also be asked to compare and contrast the study cap with any other attenuating or non-attenuating cap that has been previously worn. At the conclusion of the study, statistical analysis will be performed to determine the differential levels of exposure between the primary and secondary operators, between different sides of the head, and the attenuation ability of the XPF cap. The dosimeters on the outside of the cap will serve as the control in evaluating the attenuating ability of the cap compared to the corresponding dosimeters on the inside. Each dosimeter location on the outside of the cap will be compared to the other locations for both the outside and the inside sets. And finally, the exposure measurements will be compared between the primary and secondary operators for each dosimeter location. The specific factors listed above that affect operator exposure will be taken into account as well.