Occupational radiation exposure to nursing staff during cardiovascular fluoroscopic procedures: A review of the literature

Abstract Fluoroscopy is a method used to provide real time x‐ray imaging of the body during medical procedures to assist with medical diagnosis and treatment. Recent technological advances have seen an increase in the number of fluoroscopic examinations being performed. Nurses are an integral part of the team conducting fluoroscopic investigations and are often located close to the patient resulting in an occupational exposure to radiation. The purpose of this review was to examine recent literature which investigates occupational exposure received by nursing staff during cardiovascular fluoroscopic procedures. Articles published between 2011 and 2017 have been searched and comprehensively reviewed on the referenced medical search engines. Twenty‐four relevant studies were identified among which seventeen investigated nursing dose comparative to operator dose. Seven researched the effectiveness of interventions in reducing occupational exposure to nursing staff. While doctors remain at the highest risk of exposure during procedures, evidence suggests that nursing staff may be at risk of exceeding recommended dose limits in some circumstances. There is also evidence of inconsistent use of personal protection such as lead glasses and skull caps by nursing staff to minimize radiation exposure. Conclusions: The review has highlighted a lack of published literature focussing on dose to nurses. There is a need for future research in this area to inform nursing staff of factors which may contribute to high occupational doses and of methods for minimizing the risk of exposure, particularly regarding the importance of utilizing radiation protective equipment.


| INTRODUCTION
Fluoroscopy is a method used to provide real time imaging of the body during medical procedures. It utilizes x-rays which pass through the patient to visualize internal structures. Historically x-ray fluoroscopy was primarily used for diagnosis, but recent advances in both imaging and procedural equipment have led to considerable growth in the range of fluoroscopically guided procedures, particularly in the field of interventional cardiology, (IC) and vascular intervention. [1][2][3] Interventional cardiovascular (CV) cases are often less costly than surgery and allow medical intervention to be conducted in a minimally invasive way, reducing the risk to the patient. 4 Although very useful for imaging, ionizing radiation may result in several detrimental effects to those exposed, including cellular damage, malignancies, and cataracts. [5][6][7][8] The greatest risk of occupational exposure occurs when the primary x-ray beam strikes the patient's skin and scatters, a portion of the x-ray photons are absorbed and scatter in the patient's body. 9 Scattered radiation levels near the patient can be relatively high, even under routine working conditions, and staff are subsequently exposed while conducting CV procedures. 1,10 There has been justifiable concern over the dose received by the physicians operating in this environment, but data detailing exposure to supporting staff during fluoroscopic procedures are scarce. 1,11,12 The fundamental premise is to keep exposure to ionizing radiation as low as reasonably achievable (ALARA) 6,13 and organizations such as the International Commission on Radiological Protection (ICRP) recommend dose limits to those that are occupationally exposed. 14 Staff radiation monitoring is performed as locally legislated to ensure that departments are complying with regulatory occupational dose limits, but problems with effective monitoring have been highlighted partly due to the attitude and radiation safety culture of staff. 15 Poor adherence to the ICRP recommendation to conduct measurements using two dosimeters, one worn above and the other underneath the lead apron, as well as irregular use of personal dosimeters and has been emphasized, 16 and it has been reported that appropriate dosimetry is essential to provide reasonable estimations of dose to the lens of the eye. [17][18][19] There has been increasing concern over recent epidemiological evidence suggesting that radiation-induced cataracts can occur at much lower doses than previously assumed. [20][21][22] Staff involved in fluoroscopic CV procedures have demonstrated an elevated incidence of radiation-associated lens changes. 16,21,[23][24][25][26] In response, in 2011 the ICRP recommended reducing the occupational dose limit for the eye from 150 mSv (millisievert) to 20 mSv per year. 27 This has resulted in numerous studies investigating the lens dose received by fluoroscopic operators, but there is very little research evaluating the risk of occupational eye exposure for nursing and allied health staff. 1,11,19 Nurses are an integral part of the team conducting CV procedures, and many cases require staff to stand adjacent to the patient resulting in inadvertent exposure to radiation. To minimize the risk of exposure, it is vital that occupational dose to individuals is monitored and quantified. To date, the occupational exposure to nurses within the CV setting is widely unexplored.

1.A | Review objective
The purpose of this review is to provide a current account of research specifically examining occupational dose to nursing staff during x-ray guided CV procedures. It will compare results of publications within procedural contexts, critically review the findings, and assess areas in which further research would be beneficial.

| MATERIALS AND METHODS
A search for relevant literature published between 2011 and 2017 was undertaken between November 2016 and June 2017 to retrieve articles related to occupational radiation dose to nursing staff present during fluoroscopically guided CV procedures. A combination of keywords was used correlated to occupational radiation dose to nurses, i.e.: "nurse occupational dose", "nursing fluoroscopy", "staff fluoroscopy dose", and "occupational fluoroscopy dose". Search terms were purposefully general to ensure that articles which did not explicitly articulate 'cardiovascular' terminology were included in the initial screening for suitability for inclusion in the review. Due to the relatively small number of identified studies, reference lists of located manuscripts were also used to detect additional articles. Due to the rapid advancements in both imaging and procedural equipment in the last decade, searches were limited to those published after 2010 to ensure relevance to current operating practices.
A total of thirty potentially relevant articles were identified and of these six articles were excluded from the review as the investigated radiation doses to nurses were not directly related to the imaging of the CV system as illustrated in Fig. 1

2.A | Radiation dose monitoring
It has been demonstrated that the dose to nursing staff during fluoroscopic procedures can be similar or higher than that received by the physician [28][29][30] with evidence of an increasing trend toward higher dose levels to nurses working in this environment. 28 It is therefore important to quantify the radiation exposure to individuals working within fluoroscopic departments. [31][32][33] Typically, the devices used to evaluate the individual cumulative radiation exposure are personal dosimeters, which are usually badges worn by occupationally exposed staff during procedures.
The ICRP recommends the proper use of personal monitoring badges in interventional fluoroscopic laboratories to monitor and audit occupational radiation dose. 14 There was a variety of styles, anatomical positioning, and calibration of dosimeters utilized in the reviewed literature (Table 2). Active dosimetry systems, such as DoseAware (Philips Medical Systems, Amsterdam, The Netherlands) provide real time visualization of radiation dose rate. It consists of a personal dosimeter worn by staff [ Fig. 2(a) (SD, 0.01). 39 None of these reductions were reported as statistically significant with one cited explanation the possibility that the nurses had a restricted view of the readout monitor during cases, but it is acknowledged that real time dose feedback can be effective in dose reduction. [35][36][37][38][39] 2.B | The effect of equipment and staff location Radiation scatter is the primary mechanism of operator and staff exposure, and understanding the factors that can affect its magnitude and distribution is essential. 40 As X-ray scatter from the patient is the primary source of radiation dose to in-room personnel, 41 staff location within the fluoroscopy room influences the level of occupational exposure. 1,19,42 In x-ray guided CV procedures, the area of greatest scatter alters as the geometry of the x-ray tube changes ( Fig. 3). 43 Nursing staff may undertake several roles within fluoroscopic suites, and the in-room location of the nurse may vary during procedures. In many of the reviewed articles, the role of the nurse was not well-defined and it was unclear whether staff were performing the scrub or scout role 12,32,35,[44][45][46] and consequently reported data may represent an average of the dose of both duties.          during the same procedure. 31 The authors also identified that personal behavior within the fluoroscopic suite alters dose considerably.
Depending on their responsibilities during the procedure nurses may have greater opportunity of deliberately increasing their distance from the patient resulting in a decrease in dose. 1,25,29,39 Some authors investigated dose in relation to proximity to the xray tube. 25,34,38,[47][48][49] Explanatory diagrammatic representation of the position of staff was provided in several articles 25,38,[47][48][49] which allows comparison by dosimetric location rather than assigned role.
Specific articulation of staff distances from the x-ray tube or

2.C | Lead shielding
Lead shielding refers to the use of lead, or lead equivalent products to shield staff from radiation. Variations in accessibility and utilization of lead shielding devices by staff in fluoroscopic suites have been well documented 50,51 and this has been reflected in reported use of personal protection in the reviewed studies (Table 3). Thyroid shields were either not worn 12,44 or inconsistently worn by staff at some centers. 52 Only one reviewed article specifically articulated the use of a lead skull cap during fluoroscopic procedures and was utilized by the operator only. 11 Lead glasses also had varying degrees of use with several studies reporting that while doctors routinely used lead eye protection, nursing staff did not. 11,19,44,47,53 Consideration should also be given to the location of lead protection. This may include items such as ceiling mounted lead glass, table mounted, or stand-alone lead shields (Fig. 4). This equipment provides a barrier between the scattered radiation from the patient and the staff member, but correct positioning is vital for effective dose minimization. 54 The importance of careful positioning of the movable ceiling mounted lead shield has been previously reported 55 especially when using biplane equipment, 56 and this was echoed in the reviewed literature. 1,11,19,25,31,32,34,35,46,48,52,53 (Table 2). 1,11,47,48,52 Several studies positioned dosimeters external to protective lenses 19,44,[46][47][48]   acquisitions 31 and increasing staff distance during acquisitions especially when using large tube angles. 31,38 Adequate staff training and education were also seen as essential, and this was successfully supplemented by using real time feedback monitors. 34 38 Physicians should also let other in-room staff know of an impending DSA acquisition so that the staff know to not approach the patient and stay behind shielding if possible. 38,63 Research indicates a considerable number of parameters which can cause a significant variation in resultant dose levels during fluoroscopic cases, even within the same type of procedures. 1 The Optimization of RAdiation protection for MEDical (ORAMED) staff study also revealing a large variability of practices between cases and workplaces. 56 Given the variation in procedure type, operator, tube geometry, and staff position, correlation of dose conditions within differing procedures proved difficult. This was exacerbated by the different reporting values used by the authors.

2.E | Imaging parameters
The ICRP notes that radiation training may be lacking which may result in a radiation safety issue for staff as well as patients 69 and recommends that departments implement an effective optimization program through training and raising consciousness of radiology protection in individuals. 70 The effectiveness in dose reduction to staff following radiation education has been highlighted 65,66,71 as has the need for radiation training of occupationally exposed nursing staff. 72 Several authors noted that nursing staff are at risk of exceeding recommended dose levels if radiation protection tools are not properly used. Given the variables that exist for nursing staff during fluoroscopic procedures, dose minimization is not as simple as increasing distance from the source of the scattered radiation. Given the invisible nature of radiation, staff should be provided with appropriate information and training to highlight factors which influence dose allowing them to become conscious contributors to personal dose minimization.

CONF LICT OF I NTEREST
The authors declare no conflict of interest.