Radiation Tracking in the Cardiac Catheterization Lab

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. The information gathered in the beginning of this process revealed that there appeared to be less correlation than was supposed between fluoro time and the amount of radiation the equipment calculated and recorded as being received. Only one factor seemed to determine high radiation doses: difficult and complicated procedures with prolonged acquisition times. We found that potentially long procedures such as pulmonary vein ablation (PVA) and abdominal aortic aneurysm (AAA) exclusion patients received an average of only about 1000 to 2000 mGy in most cases, since electrophysiology (EP) cases primarily utilize fluoro and our physicians usually use a 7 fps setting for peripheral cases rather than the 15 to 30 fps used in coronary cases. However, in complicated and lengthy coronary interventions, the radiation dosage can exceed 6000 mGy, and in some cases, there was in excess of 8000 mGy in a single case. With the increase in multiple stents and/or multi-vessel procedures and an increase in the acuity of patients, the difficulty of the cases seemed to have increased significantly. This often translates into more lengthy acquisition times, and therefore more radiation exposure to the patient. St. Luke's Episcopal Hospital Cath Lab's most recent safety measure is the ability to compare the previous six months of radiation doses to the upcoming cath lab schedule in order to determine if anyone on the schedule has received a large amount of radiation cumulatively over the previous six months. This program has already allowed the cath lab to alert several physicians of a patient’s dosage before the patient received another procedure that would put them closer to possible tissue injury and/or a reportable sentinel event. Armed with this information, action plans were instituted during these cases that helped to prevent excessive radiation exposure and exceeding the limits recommended by JCAHO. Some of the options used to prevent excessive radiation have included using the last fluoro stored rather than taking as many cine runs, limiting steep angles if possible, adjusting the table height and other external steps that are within our control. Utilizing the last image fluoro stored can only be utilized in our newer rooms, since the older equipment does not have this capability. Therefore, we had to re-arrange schedules so that these patient procedures could be done in one of the newer rooms. It is important to note that the last fluoro stored feature comes routinely with all of the newer imaging equipment, but not with older systems. Though the feature comes routinely with the software in new equipment, it is not necessarily programmed or activated (read your contract). In addition, some lab configurations may require another monitor on the boom. The cath lab also experienced some physicians opting for a different modality altogether in order to benefit the patient. The physicians routinely discuss the situation with the patient once they are notified of an upcoming procedure that may result in excessive radiation. One physician agreed to eliminate the procedure at the request of the patient once they discussed the risks and benefits of additional procedures with ionizing radiation. Currently, this ability to compare dosages over a six-month period is only utilized in the cath lab. The interventional radiology department has expressed interest in sharing data so a more complete picture can be maintained on each patient seen throughout the hospital. It is our hope that in the future, St. Luke’s Episcopal Hospital will be able to offer this to every patient throughout the hospital. In conclusion, maintaining a patient database for cumulative doses for a six-month period has resulted in a more accurate identification of those patients who may receive higher doses of radiation. When patients are identified as potential candidates, steps can be instituted to lessen the amount of radiation received during a procedure if it is deemed necessary to continue with the procedure. Also, when patients are identified before their procedures, the physician has the ability to reconsider the medical necessity and discuss with the patient the alternatives available. This patient education results in the patient having a better understanding of the benefits versus the risks of having another procedure performed. In the end, the patient, whose care is enhanced, is better educated; the physician is better informed, and the department has better control over radiation safety for not only the patient, but the entire staff. Finally, in conjunction with policies and procedures requiring a mandatory annual radiation safety in-service to all cardiologists, cardiology fellows and employees who work in environments where patients are exposed to ionizing radiation, these actions enhance the safety of patients who have been exposed or may be exposed to ionizing radiation during invasive and interventional cardiac procedures. The authors can be contacted at dduree@sleh.com. Note: This article underwent double-blind peer review by members of the Cath Lab Digest Editorial Board.

How do you document patient dosage? Does your hospital have a space on a patient electronic record showing cumulative dosage, incorporating data from the cath lab, invasive radiology and other departments? Keep the discussion going in CLD! Email us at: cathlabdigest@aol.com.

1. The Joint Commission. (2007). IV. Reviewable Sentinel Events. Sentinel Event Policy and Procedures. Retrieved July 17, 2007 from http://www.jointcommission.org

2. Amis ES, Butler PF, Applegate KE, et al. American College of Radiology White Paper on Radiation Dose in Medicine. J Am Coll Radiol 2007;4:272-284.

3. Hirshfeld JW, Balter S, Brinker JA, et al. ACCF/AHA/HRS/SCAI Clinical competence statement on optimizing patient safety and image quality in fluoroscopically guided invasive cardiovascular procedures: A report of the American College of the Cardiology/American Heart Association/ American College of Physicians Task Force on Physicians Task Force on Clinical Competence (ACCF/AHA/HRS/SCAI Writing Committee to Develop a Clinical Competence Statement on Fluoroscopy. Am J Coll Cardiol 2004;44:2259-2282.