Objective: Ionizing radiation is an unseen and often unappreciated safety concern for patients and cath lab staff. Radiation exposure has both deterministic and stochastic effects, with patient risk estimated by peak Skin Dose and Air kerma Area product. In our lab exposure guidelines have been set for radiation safety (fluoro time < 60 min, 4,000 mGray and 20,000 cGray cm2). A prior audit of practice 2011-2013 found that 17.1% (758/4,439) of patients undergoing interventional procedures exceeded these limits. Safer radiation practices were implemented including: intra procedure operator feedback, decrease in cine frame rate and run length, promote mapping and less angled views. However changing patient characteristics (increased obesity, prior CABG) and an increase in structural procedures warrant reexamination of practice.
Procedure: The frequency of guideline excessive radiation exposure for cardiac cath lab patients was tracked over a 12 month period from 11/2016-11/2017. The frequency of radiation exposure exceeding our guidelines was tracked overall and by operator (16), and by specific intervention.
Results: Over the one year period 10.2% of interventions [174/1,702] received excessive skin or total body radiation. Rates exceeding guidelines by operator ranged from 4% to 26% with operators performing structural or peripheral procedures having the highest patient radiation exposures. Structural procedures resulted in exposures as high as 123 min fluoro time, TAD of 226,385 cGray cm2, 11,129 mGray skin dose [patient had post procedure skin damage]. Factors associated with high radiation exposures included: increasing obesity, prior surgical revascularization, coronary anomalies, multivessel procedure or high complexity procedure, difficulties in imaging requiring highly angled or multiple views, procedural complications. Interventions associated with limiting exposure included: limiting fellow participation, decrease in frame rate, interim stills with limited cine runs. The default settings of X-Ray equipment have been modified to encourage safe and appropriate use of radiation in the cardiac catheterization lab (however, physician overide of settings is still possible).
Conclusions: The changes made in imaging equipment and procedures 5 years ago have been largely sustained and have resulted in less frequent radiation outliers. Patient factors (e.g. obesity, prior CABG) complex and multivessel interventions, structural and vascular procedures are potentially frequently associated with excess radiation. Changing default settings and implementing radiation safety practices, including staging where appropriate, can significantly decrease radiation exposure to patients and staff. Cumulative and target organ specific patient doses of radiation should be tracked and more readily accessible in the patient’s medical record.