Radiological risk analysis of image-guided interventional procedures

Image-guided interventional procedures have become one of the medical applications that produces the highest doses of radiation for both the patient and the personnel involved in it. Safety assessment was applied to a generic service where image-guided interventional procedures was carried, using the semi-quantitative method of risk matrix, implemented in the Cuban SECURE-MR-FMEA code. The process map was prepared, identifying 6 stages with 76 accidental sequences. Values showed that the first screening for the developed model reports 45 % of high risks, 42% and 13 % of moderate and low risks, and once the number of controllers increased, high risks decrease to 11 % and there is an increase in moderate and low risks of 54 % and 35 % respectively. These results stress the importance of using all necessary measures for the protection of the public, patients and occupationally exposed workers.


INTRODUCTION
Minimally invasive image-guided interventional procedures have expanded the scope of medical practice across numerous domains of medicine, owing to the demonstrated benefit to patients [1]. The use of this technique has multiplied vertiginously in recent times, also turning into one of the medical applications that produces the highest doses of radiation for both the patient and the personnel involved in the procedure [2], as well as the possible occurrence of deterministic effects. One way to reduce the occurrence of these incidents is through prospective risk analysis, which is focused on the prevention and mitigation of their consequences. For this reason, the goal of this work is to analyze the radiological risk in a generic service for image-guided interventional procedures.
There is a potential danger in believing that modern equipment and new technologies require less quality control and highly skilled maintenance. Therefore, to avoid the occurrence of adverse situations, there must be adequately trained personnel, sufficient material resources, an implemented quality assurance program and ongoing training [3].

MATERIALS AND METHODS
This research was focused in a generic service where image-guided interventional procedures are performed. To obtain the accidental sequences, reports on radiological incidents and accidents that occurred during interventional procedures were taken into account (Figure 1), as mentioned in the following bibliographic references [1,2,[22][23][24][25][26][27][28][29], publications where the risk matrix methodology has been applied, and through consultation with experts. The methodology used for this process is illustrated in the algorithm of Figure 2.  's back 21 months after a coronary angiography and   two angioplasty procedures within a three-day period; assessed cumulative dose 15,000 to 20,000 mGy. The patient has consistently refused skin grafting after excision of necrotic tissue. B -Cataract in the eye of an interventionist after repeated use of old x-ray systems and improper working conditions related to high levels of scattered radiation.
Source: ICRP 85 "Avoidance of radiation injuries from medical interventional procedures " Since a generic algorithm was created for obtaining and validating accidental sequences ( Figure   2), which will be applicable to any process in which image-guided interventional procedures are performed, the first step was to define the process to identify its stages. The initial accidental sequences were elaborated where the initiators to be included in each stage are identified, as well as their barriers (B), consequences (C), frequency (FR) and consequence (CR) reducers. To form the final sequences, a validation process was conducted, during which the analysis methods specified in SECURE-MR-FMEA were consistently applied. The process involves multiple actors (PAC, PUB, OEW), which can result in different consequences for the initiators. Accidental sequences form a chain of initiating events that possibly end in undesirable consequences, including accidental exposure [10]; being useful for these cases to apply the risk matrix approach, which is an effective tool in the risk management of a facility from the combined analysis of the frequency of an adverse event (f), the probability of failure of the existing barriers (P) and their consequences (C) [7]. Although this methodology does not allow risk to be numerically quantified, it facilitates it possible to classify risk into levels, which is accurate to establish priorities, without the need for more precise risk analysis [4].
Safety measures or barriers detect, prevent, avoid and stop an accidental sequence or mitigate its consequences. Security measures can be technological, such as alarms, or of an organizational nature, such as procedures or double checks to avoid or detect an error. These are all part of the principle of defense in depth [16]. Procedures that reduce the probability of occurrence of the initiating event or the severity of the consequences are called frequency (FR) or consequence (CR) reducers, respectively. The robustness of barriers, frequency and consequence reducers was obtained from the criteria established in basic bibliographies [7,10,13,15].
To determine the types of consequences [7], cases that could affect the public, patients or OEW were analyzed. The risk analysis was carried out with the SECURE-MR-FMEA code [4][5][6], this is a code developed in Cuba with the objective of carrying out comprehensive risk studies of practices involving ionizing radiation. This code interconnects prospective methods (risk matrix and FMEA) and an own database with reactive capabilities for incident learning. For this occasion, the risk matrix, which is one of the methods implemented in the software, was employed.

RESULTS AND DISCUSSION
For the radiological risk in image-guided interventional procedures (RRF), 6 stages are identified (Table 1)   Applying the second screening, the risk level profile is obtained for each stage of the radiological risk in image-guided interventional procedures (Table 1), the main initiating events, the barriers, the most important reducers and consequences are analyzed. The difference in the results of the aforementioned risk profiles are observed in the pie charts ( Figure 3). For the first profile (higher), the existence of 45% high risks (HR), 42% moderate risks (MR) and 13% low risks (LR) of the total number of evaluated sequences was identified, by applying a greater number of risk drivers in a second screening, gradually decreased to 11% high risk (HR), and there is a rise in moderate (MR) and low (LR) risks of 54% and 35% respectively. The latest information mentioned shows that for high risk (HR), 8% corresponds to PAC and 3% to OEW, for moderate risk (MR), 38% is for PAC, 14% for OEW, and 1% for PUB, and for low risk (LR), 11% is for PAC, 17% for OEW, and 8% for PUB.      On the other hand, Figure 5  sequences, respectively. Table 4 shows the aforementioned barriers in more detail.  The percentage analysis of the level of severity of the consequences can be seen in Figure 6, where the moderate consequences (M) in the OEW are 26%, the very serious consequences (VS) and serious (S) in patients with the 19% and 18% in that order. This highlights the importance of applying optimization for this type of study. The increased variety, frequency, and complexity of these procedures, sometimes with relatively high radiation doses, and the involvement of personnel with insufficient training in radiation protection, pose challenges for managing patient dose and ensuring occupational safety. Patients may be at risk of tissue reactions (temporary and permanent erythema, temporary and permanent epilation, etc.), and both patients and staff are at increased risk of stochastic effects. In addition, OEWs who do not comply with all security measures are at risk of temporary epilation, hand injuries and cataracts caused by radiation.  Number and robustness of each consequence on the x-axis and the legend of the graph.