Cath Lab Digest

Patient safety is always a primary goal in any hospital and radiation safety ranks high on the list of safety items for a catheterization laboratory. The U.S. Nuclear Regulatory Commission (NCR) and the Food and Drug Association (FDA) regulate the use of radioactive materials in medicine and the manufacture of devices that emit radiation, respectively. The Joint Commission (TJC), more commonly referred to as the Joint Commission on Accreditation of Healthcare Organizations (JCAHO), also regulates safety through its accreditation process. JCAHO has made the statement that prolonged fluoroscopy with cumulative dose >1500 rads to a single field or any delivery of radiotherapy to the wrong region or >25% above the planned dose1 constitutes a reviewable sentinel event. Since that recommendation, medical facilities have been under intense pressure to provide the safest possible environment for radiation safety for their patients.

With all the medical diagnostic procedures performed today that require the use of ionizing radiation, the cath lab at St Luke’s Episcopal Hospital in Houston, Texas, began to develop a plan to meet JCAHO’s recommendations. The American College of Radiology (ACR) also recommends keeping information on radiation doses archived to provide for quality comparisons and to identify patients at risk due to multiple radiation procedures. According to a white paper issued by the ACR in 2007:

…there should be special attention paid to the practical suggestions set forth in this paper, such as education for all stakeholders in the principles of radiation safety, the appropriate utilization of imaging to minimize any associated radiation risk, the standardization of radiation dose data to be archived during imaging for its ultimate use in benchmarking good practice, and, finally, the identification and perhaps alternative imaging of patients who may have already reached threshold levels of estimated exposure from diagnostic imaging.²

St. Luke's Episcopal Hospital cath lab performs approximately 10,000 to 12,000 procedures a year. As is the case in most cath labs, many patients come in for repeat procedures. As a result, management teams decided to track the cumulative amounts of radiation received by all patients who had undergone fluoroscopic and selective cardiac procedures within a six-month period. This plan was initiated because many inpatients and/or outpatients may receive multiple procedures that could expose them to the possibility of significantly more direct radiation than what they would receive in the cath lab in a single case. Our lab made tracking of cumulative radiation doses one of our goals in order to provide for the safety of patients. Our equipment currently displays a total dose in mGy and DAP in cGycm2 at the end of each case. This dose is incorporated into the medical record and stored in a program used to track cumulative doses. This is only a total dose and does not take into account the different angles utilized or areas of the body where the cine runs are taken. Therefore, the Radiation Safety Officer (RSO) at St. Luke's Episcopal Hospital chooses to review all cases with total dose over 12000 mGy.

The department quality coordinator retrospectively reviews all radiation exposure doses received by patients that underwent procedures in the cath lab the previous day to determine if anyone exceeded the 12000 mGy in a single case. We found that while many procedures in the laboratory were well below the lower range of 460 mGy, there were some that received a much higher dose of radiation as well. With the approval of the Cardiac Catheterization Laboratory Advisory Committee (CCLAC) and the RSO, the cath lab developed and implemented action plans to reduce the amount of radiation patients received. The process began by setting all x-ray equipment to deliver 15 frames per second (fps) unless indicated otherwise by the cardiologist. The cath lab instituted a daily review of all radiation exposure doses and kept a spreadsheet in order to gather information on cumulative doses. The CCLAC instituted several arbitrary doses, at which steps are taken to try and prevent excessive radiation exposure to the patients. At 8000 mGy, the staff notifies the cardiologist of the patient’s radiation dose and at 12000 mGy, a warning is given to the cardiologist, at which time he/she may decide if the benefit of continuing the procedure outweighs the risk. Any dosage that equals or exceeds 12000 mGy is forwarded to the RSO to review. The CCLAC/RSO chose to use the arbitrary dose of 12000 mGy for notification and review by the RSO, since the calculation by the equipment is only total dose and does not take into effect many other criteria. The thinking was that it would warn the physician before 1500 rads were received and might prevent an actual sentinel event.

If the RSO has to review the case, the information from the case which includes not only the dose but patient height, weight, and angles of projection and the number of frames taken with each cine run, is reviewed by the RSO and used to make a determination of whether the patient received an excessive dose to one body field. Any case that exceeds 15000 mGy to any one body part as calculated by the RSO will be subjected to a root cause analysis to determine if anything can be done in the future to prevent this occurring again and if the case constitutes a reportable sentinel event. The RSO also provides a mandatory annual radiation safety inservice to all employees and cardiology fellows who work in environments where patients are exposed to radiation.