Abstract
Background
Interventional cardiologists have one of the highest annual radiation exposures yet systems of care that promote radiation safety in cardiac catheterization labs are lacking. This study sought to reduce the frequency of radiation exposure, for PCI procedures, above 1.5 Gy in labs utilizing a Phillips system at our local institution by 40%, over a 12-month period.
Methods
We performed a time series study to assess the impact of different interventions on the frequency of radiation exposure above 1.5 Gy. Process measures were percent of procedures where collimation and magnification were used and percent of completion of online educational modules. Balancing measures were the mean number of cases performed and mean fluoroscopy time.
Interventions
Information sessions, online modules, policies and posters were implemented followed by the introduction of a new lab with a novel software ( AlluraClarity © ) to reduce radiation dose.
Results
There was a significant reduction (91%, p < 0.05) in the frequency of radiation exposure above 1.5 Gy after utilizing a novel software ( AlluraClarity © ) in a new Phillips lab. Process measures of use of collimation (95.0% to 98.0%), use of magnification (20.0% to 14.0%) and completion of online modules (62%) helped track implementation. The mean number of cases performed and mean fluoroscopy time did not change significantly.
Conclusion
While educational strategies had limited impact on reducing radiation exposure, implementing a novel software system provided the most effective means of reducing radiation exposure.
Highlights
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Education strategies had limited impact on reducing radiation exposure in one healthcare institution.
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A novel software system provided the most effective radiation exposure reduction.
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Number and duration of cases did not change significantly with these initiatives.
1
Introduction
As a form of ionizing radiation, exposure to x-rays can produce a number of health concerns. The lifetime excess cancer risk for an interventional cardiologist is in the order of 1 in a 100 above the background risk . The risks involved are typically divided into deterministic and stochastic effects.
Deterministic effects are dose-dependent and can cause injuries to organs such as the skin and eyes. Stochastic effects have no minimum dose threshold; rather, any amount of exposure can lead to DNA damage and subsequent cancers such as brain tumors . For protection against these effects, medical personnel are required to wear a number of protective apparel including lead aprons, goggles and thyroid collars ( Supplement A ).
In order to better understand the local radiation safety problem, a point prevalence study was performed to look at the radiation dose in one of the local labs utilizing the Philips x-ray system. This showed a highly variable cyclical radiation dose and a high frequency (n > 10) of exposure above 2 Gy for Air Kerma (AK).
Several recent studies evaluated techniques to reduce radiation exposure in the cardiac catheterization lab . Some of these interventions were system-based such as using a default low fluoroscopy dose at the start of every procedure. Other interventions were provider-based interventions such as the use of posters and checklists.
The aim of this quality improvement (QI) initiative was to employ some of the previously described interventions from the literature to reduce the frequency of radiation exposure, for PCI, above 1.5 Gy as measured by AK in the cardiac catheterization lab of our local institution by 40% over a 12-month period. The purpose of choosing 1.5 Gy as a cutoff is due to the known increased risk of skin injury for the patient at doses above 2 Gy.
2
Methods
An ethics review assessment tool was used to determine that this QI project did not necessitate a full research ethics board review and approval, as long as there was adherence to professional codes of conduct, role responsibilities, appropriate supervision, and following of hospitals policies and procedures.
2.1
Interventions
We used the Model for Improvement QI framework. A series of plan-do-study-act (PDSA) cycles helped design, test and refine our interventions. A diagnostics process for root cause analysis was started with surveying healthcare workers in the lab and going through a Fishbone and Pareto algorithm ( Supplement B ) in order to identify key local contributors to increased radiation exposure. Each nurse, fellow and staff physician were asked to mark on a frequency chart the most common causes for increased radiation dose.
2.1.1
Provider-based interventions
The Pareto diagram was used to help identify initial areas for change ideas. The first intervention was an information session that was led by the chief radiation officer. This assumed a lack of awareness of radiation safety as suggested by the Pareto diagnostic diagram ( Supplement B ) showing excessive use of cine and high dose fluoroscopy as potential contributors. This intervention took place in January 2016 and consisted of a 1-h session during the regular cardiac catheterization lab-meeting day. There was only about 50% attendance rate among healthcare workers.
The second intervention was the introduction of corporate policies on radiation safety in the catheterization lab. This was implemented in January 2016 and mandates training on radiation safety prior to working in the catheterization lab. Due to a lower attendance in information sessions; this intervention assumes the need for an enforcing policy to bring about change especially when it pertains to safety of patients and workers.
The third intervention was in the form of poster with a mnemonic that helps remind operators of key behaviors to help reduce radiation exposure. This assumes that operators tend to forget certain techniques to minimize radiation exposure. The poster ( Supplement C ) was placed in all of the cardiac catheterization labs in April 2016.
The fourth intervention was the implementation of online educational radiation safety module. This assumes that healthcare workers might be too busy to attend information sessions in person, as reflected by the lower rates of attendance to information sessions.
2.1.2
System-based interventions
Despite multiple PDSA cycles as above, the observation during the study phase was that there was lack of complete adherence to proposed provider-based interventions. The fifth intervention was the use of a novel x-ray software system; the AlluraClarity © system. This novel system was introduced in a new lab (lab 3 as shown in Fig. 1 A ) June 2016 and employs a number of forced technical changes as well as programmable changes with the aim of reducing radiation dose while still maintaining an adequate image quality. Some of these changes include reducing the frame rate from 15 frames per second (fps) to 7.5 fps and fine-tuning x-ray parameters (eg peak tube voltage, cathode current spectral filter) to the examination and patient size. This software has been successful in other hospitals in significantly reducing the radiation dose .
2.2
Evaluation of interventions
To evaluate the efficacy of the interventions, the radiation dose, as measured by AK, was recorded after every PCI procedure. The fluoroscopy time was also recorded at the end of each procedure. We recorded readings from 3 different Phillips labs. Labs 1 and 2 were the non AlluraClarity © system labs whereas lab 3 was the new lab with AlluraClarity © system, introduced in June 2016. The number of PCI procedures every month was tracked. The study period ran from November 10th 2015 to November 10th 2016.
A family of measures was tracked throughout the study. The primary outcome measure was the frequency of procedures exceeding 1.5 Gy . This was measured in lab 2 (baseline Phillips lab, November to June 2016) and then in lab 3 (new Phillips lab with AlluraClarity © system from June 2016 onwards). Process measures included the percent use of certain radiation reduction maneuvers such as the percent use of collimation function and the percent use of magnification function. Another process measure was the percent completion of online modules on radiation safety. The balancing measures were the mean total number of PCI procedures completed and the mean fluoroscopy time.
2.3
Analysis
We used statistical process control (a time-series analysis commonly used in quality improvement) to compare monthly radiation dose exposure as measured by AK at baseline (November 10th 2015) and following initiation of the interventions over a 12-month period (November 10th 2015 to November 10th, 2016). This outcome measure was analyzed using an X-bar S Chart because it represents unequal subgroup size (n > 1). Control limits of XbarS-chart were set at 3 σ (equivalent to 3 Standard Deviations) where consecutive points below the lower control limits (LCL) represent a significant decrease equivalent to p < 0.01. All analyses were performed with Excel (Version 15.0) and QI Macros (KnowWare International Inc., Version 2013.07). The outcome measure of frequency of procedures exceeding 1.5 Gy was also compared against baseline (frequency of procedures above 1.5 Gy in November 2015) using Chi Square test. The process measures and balancing measures were also analyzed using an XbarS chart.
2
Methods
An ethics review assessment tool was used to determine that this QI project did not necessitate a full research ethics board review and approval, as long as there was adherence to professional codes of conduct, role responsibilities, appropriate supervision, and following of hospitals policies and procedures.
2.1
Interventions
We used the Model for Improvement QI framework. A series of plan-do-study-act (PDSA) cycles helped design, test and refine our interventions. A diagnostics process for root cause analysis was started with surveying healthcare workers in the lab and going through a Fishbone and Pareto algorithm ( Supplement B ) in order to identify key local contributors to increased radiation exposure. Each nurse, fellow and staff physician were asked to mark on a frequency chart the most common causes for increased radiation dose.
2.1.1
Provider-based interventions
The Pareto diagram was used to help identify initial areas for change ideas. The first intervention was an information session that was led by the chief radiation officer. This assumed a lack of awareness of radiation safety as suggested by the Pareto diagnostic diagram ( Supplement B ) showing excessive use of cine and high dose fluoroscopy as potential contributors. This intervention took place in January 2016 and consisted of a 1-h session during the regular cardiac catheterization lab-meeting day. There was only about 50% attendance rate among healthcare workers.
The second intervention was the introduction of corporate policies on radiation safety in the catheterization lab. This was implemented in January 2016 and mandates training on radiation safety prior to working in the catheterization lab. Due to a lower attendance in information sessions; this intervention assumes the need for an enforcing policy to bring about change especially when it pertains to safety of patients and workers.
The third intervention was in the form of poster with a mnemonic that helps remind operators of key behaviors to help reduce radiation exposure. This assumes that operators tend to forget certain techniques to minimize radiation exposure. The poster ( Supplement C ) was placed in all of the cardiac catheterization labs in April 2016.
The fourth intervention was the implementation of online educational radiation safety module. This assumes that healthcare workers might be too busy to attend information sessions in person, as reflected by the lower rates of attendance to information sessions.
2.1.2
System-based interventions
Despite multiple PDSA cycles as above, the observation during the study phase was that there was lack of complete adherence to proposed provider-based interventions. The fifth intervention was the use of a novel x-ray software system; the AlluraClarity © system. This novel system was introduced in a new lab (lab 3 as shown in Fig. 1 A ) June 2016 and employs a number of forced technical changes as well as programmable changes with the aim of reducing radiation dose while still maintaining an adequate image quality. Some of these changes include reducing the frame rate from 15 frames per second (fps) to 7.5 fps and fine-tuning x-ray parameters (eg peak tube voltage, cathode current spectral filter) to the examination and patient size. This software has been successful in other hospitals in significantly reducing the radiation dose .
