Radiation Safety for Physician Assistants in the Orthopaedic Operating Room

Fisher, Michael T. MPAS, PA‐C; Riehl, John T. MD

JBJS Journal of Orthopaedics for Physician Assistants:
doi: 10.2106/JBJS.JOPA.16.00016
Articles
Abstract

In most orthopaedic operating rooms, providers are routinely exposed to ionizing radiation associated with the use of fluoroscopy. There have been several reviews addressing the amount of radiation the primary surgeon is exposed to, but to the best of our knowledge, there has not been a systematic review of the amount of radiation to which the first assistant is exposed. We conducted a systematic review of the PubMed database to find studies measuring the amount of radiation exposure to providers in the orthopaedic operating room. Ten studies were included in the review. The results showed that, generally speaking, radiation doses for the first assistant were lower than the recommended occupational exposure levels. However, the amount of radiation that the first assistant is exposed to can vary depending on several factors, including use of personal protective equipment, distance from the C‐arm, and the role that he or she takes during the surgery. Although it appears that current fluoroscopic technique, when combined with proper radiation precautions, provides appropriate safety for first assistants, additional long‐term studies would be beneficial to determine the effects of the cumulative amount of radiation exposure.

Author Information

1Orthopaedic Trauma, Baptist Medical Group, Pensacola, Florida Investigation performed at Orthopaedic Trauma, Baptist Medical Group, Pensacola, Florida

Disclosure: The authors indicated that no external funding was received for any aspect of this work. On the Disclosure of Potential Conflicts of Interest forms, one or more of the authors checked “yes” to indicate that the author had a relevant financial relationship in the biomedical arena outside the submitted work.

Article Outline

There are many hazards that orthopaedic providers are exposed to in the operating room, including ionizing radiation. Exposure to radiation in the operating room comes in 2 forms: direct (i.e., in the direct path of the beam) and scatter (i.e., radiation bounces off the intended path and is deflected away). The advent of intraoperative imaging brought a decrease in operative times, morbidity, and complications; however, modern imaging also brought an assumed increased risk of exposure to radiation.

In terms of an individual's risk of biological damage from radiation exposure, the most common terms used are absorbed dose, equivalent dose, and effective dose. “Absorbed dose” describes the effect of radiation in a tissue or organ, and is defined as “energy deposited in a small volume of matter by the radiation beam passing through the matter divided by the mass of the matter.”1 It is measured in joules (J)/kg where 1 J/kg is called a gray (Gy); 1 Gy = 100 rad. (Gy has replaced the older term rad.) “Equivalent dose” describes the biological effects of radiation and accounts for the type of radiation used (the radiation weighting factor) and the amount of radiation absorbed. The unit used is the sievert (Sv); 1 Sv = 100 rem. (Sv has replaced the older term rem.) “Effective dose” describes the risk of cancer induction based on the organ that is irradiated; it is defined by multiplying the equivalent dose for each organ by a tissuespecific weighting factor. These values are then added together to determine the effective dose (measured in Sv)1.

Annual limits for occupational radiation exposure (Table I) are based on the United States National Council on Radiation Protection and Measurements (NCRP) and the International Commission on Radiological Protection (ICRP)2,3. Of note, the 2007 recommendations from the ICRP do not include specific thyroid limits, whereas the 1990 recommendations had a thyroid limit of 300 mSv/year4. For some general perspective on these numbers, a standard posteroanterior chest radiograph has an average effective dose of 0.02 mSv, and an abdominal computed tomography scan has an average of 10 mSv5.

All individuals on Earth are exposed to constant background radiation from natural and artificial sources. Annual per capita radiation dose in the United States, including natural, medical, commercial, and industrial sources, is estimated to be around 6.0 mSv/year, with between 2.4 and 3.0 mSv/year occurring from natural sources5,6. Certain situations can result in higher than average levels of radiation exposure (e.g., a single transatlantic flight at an altitude of less than 38,000 ft [11,582 m] can expose its passengers to 0.05 mSv)7. Furthermore, pilots and flight attendants on commercial aircraft can be exposed to annual doses near 10 mSv/year if substantial protective measures are not taken8.

The majority of published studies on the subject of radiation in the orthopaedic operating room focuses on the radiation risk to the primary surgeon as a result of proximity to the C‐arm and repeated radiation exposure during surgeries. A minority of these studies also looked at the exposure to other operating room personnel, including the first assistant (e.g., assistant surgeon, physician assistant [PA], or nurse practitioner). Although the first assistant often remains within a detectable range of radiation, he or she can be standing farther away from the C‐arm than the primary surgeon. It is known that exposure to radiation exponentially decreases as distance from the C‐arm increases9. The focus of this systematic review is to gather data on first assistants and present the findings.

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Materials and Methods

Search Strategy

An exhaustive search of the PubMed database was performed. We searched for English‐language articles that had been published between January 1980 and June 2016. The keywords used in the Boolean search included safety[Title/Abstract] OR exposure[Title/Abstract] AND radiation[Title/Abstract] AND orthopaedic[Title/Abstract] OR orthopaedic[Title/Abstract] OR physician assistant[Title/Abstract] OR assistant[Title/Abstract] OR first assist[Title/Abstract] AND surgery[MeSH]. We also searched through the reference lists of the resultant articles and PubMed's “Similar Articles” tab, and included appropriate publications to ensure a complete and thorough literature review.

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Evaluating Articles and Study Quality

The titles and abstracts of the articles discovered through the literature search were evaluated, and original scientific articles involving, or indicating possible involvement of, surgical first assistants were chosen for review. After evaluating each of these articles, only those that had data involving first assistants and using a standard C‐arm were chosen for final inclusion. The selected articles were then categorized according to their level of evidence: Level I = highquality, prospective, randomized controlled trials; Level II = lesser‐quality randomized controlled trials or prospective comparative studies; Level III = case control studies or retrospective comparative studies; Level IV = case series; and Level V = nonhuman experimental studies or case reports.

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Objectives and Paper Selection

The primary objective of this systematic review was to determine how much radiation a surgical orthopaedic PA is exposed to during operations with fluoroscopic imaging. Furthermore, using collected data, we calculated the maximum number of cases/year a PA could assist in to reach the occupational limits set by the ICRP. We chose the ICRP limits because they are more restrictive than the NCRP limits. To accomplish these objectives, we searched the literature for studies that quantified the amount of radiation exposure detected at the position of the first assistant on a per‐operation basis or that could be averaged to a per‐operation basis.

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Results

The database search using the keywords outlined above resulted in a total of 128 Englishlanguage articles. Of the 128 articles, 23 pertinent publications were chosen based on review of titles and abstracts. After examining the reference lists of each of these 23 articles and PubMed's “Similar Articles,” 10 additional publications were identified. After analysis of the full text of the 33 pertinent articles, 10 were chosen for final review, 8 of which included human patients (Fig. 1). Study protocols and review papers were excluded, along with articles that reported radiation exposure for the primary surgeon only and studies in which dosimeters were not used to measure exposure. The articles used a variety of units to measure radiation exposure; we converted these units to mSv for consistency. In articles where total radiation exposure was reported for the entirety of the study, a per‐case exposure was calculated by dividing the total radiation exposure by the number of cases. The maximum number of cases that could be performed annually to reach ICRP limits also was calculated by dividing the yearly radiation limit by the per‐dose amount found in each study. For thyroid data, yearly case limits are presented using 20 mSv/year according to the 2007 recommendations based on worst‐case scenarios, and also using the 1990 recommended limit of 300 mSv.

We included 2 Level‐V papers in this review; both of these used phantom pelvic models. Results from these studies are presented in Table II. In 2014, Nelson et al.10 published a paper with the primary objective to determine the difference in radiation exposure when comparing C‐arm, O‐arm, and portable radiograph machines. The average of 3 single image acquisitions was calculated for the first assistant with only the lateral projection. No personal protective equipment (PPE) (e.g., a lead apron, a thyroid shield, or lead glasses) was used. This study concluded that current radiation safety practices provide adequate protection.

In a 1997 paper, Mehlman and DiPasquale11 described use of continuous fluoroscopy and radiation exposure rates to operating room personnel. They used clusters of 5 dosimeters that were removed after 1, 2, 3, 5, and 10 minutes of fluoroscopy. For their data, they assumed 5 minutes of fluoroscopy time for a single case. Dosimeters that had been placed under lead aprons showed no exposure. This study concluded that unprotected providers within 61 cm (24 in) of the fluoroscopic beam receive substantial amounts of radiation; therefore, they recommended the use of lead aprons, thyroid shields, and lead glasses.

Two Level‐IV papers, both of which are prospective case series, were included in this review. Results from these studies are presented in Table III. In 2001, Alonso et al.12 published a paper measuring scatter radiation during 10 surgeries that used dynamic hip screws (DHSs) for fractures of the proximal part of the femur. Operating room personnel wore dosimeters on the outside of their lead aprons. Specific data were presented in a bar graph rather than in numerical form; therefore, exposure data were estimated as closely as possible. This study concluded that operating room staff who were located >2 m from the operative field do not need to wear lead protection; if providers within a 2‐m field wear lead protection, radiation exposure will remain in safe amounts.

In a 1989 paper, Riley13 measured radiation exposure during 14 orthopaedic fluoroscopic procedures (the specific procedures were not listed). This study included 3 sham dosimeter sets; therefore, data were obtained for 11 procedures. Dosimeters were placed on the forehead (eye), the scrub‐suit collar (thyroid), the waist under the lead apron, the waist above the lead apron, and the dorsum of the dominant hand. This study concluded that radiation exposure from fluoroscopy is relatively low.

We included 1 Level‐III paper in this review. Results from this study are presented in Table IV. Baumgartner et al.14 described a 2‐phase prospective observational comparative study from 2016 with the primary objective to determine if provider knowledge of realtime dosimetry decreased radiation exposure. During the first phase (with the staff unaware of the amount of radiation exposure), the study included 39 fracture surgeries of the lower extremities (including the ankle, tibia, femur, and acetabulum); phase 2 (with the staff aware of the amount of radiation exposure) included 44 similar fractures. In both phases, the dosimeter was worn at chest level outside the lead aprons. When combining the surgeon and first assistant together, radiation exposure was significantly different between the 2 phases (p = 0.034), with a mean reduction of radiation of 13.9 μSv; however, despite a trend toward decreased radiation exposure, there was no significant difference found in exposure when looking at only the first assistant (p = 0.054). This study concluded that the use of real‐time dosimetry decreases radiation exposure; however, without real‐time dosimetry, radiation exposure is below the published limits when PPE and correct techniques are used.

We included 5 Level‐II papers in this review; all are prospective comparative studies (Table V). In a 2014 paper, Palácio et al.15 recorded radiation exposure to the surgical team during procedures for 45 transtrochanteric femoral fractures treated with DHS or sliding screw‐andplate fixation over a 6‐month period. Dosimeters were placed on the back, gonads (beneath and above the lead apron), thyroid (no lead shield), and thorax (beneath and above the lead apron); there was also a control dosimeter in a lead box. This study concluded that providers located closest to the fluoroscope receive a greater amount of radiation and that PPE can effectively prevent radiation from reaching vital organs.

In a 2012 paper, Khan et al.16 measured radiation exposure to the surgical team during surgery for 50 fractures of the proximal part of the femur that were treated with a DHS. Dosimeters were placed on the forehead, the thyroid, and the tip of the dominant index finger. The surgeon was positioned between 45 and 60 cm from the surgical field on average, and the first assistant was >60 cm away from the surgical field; however, the first assistant's hands were “quite close to the operative field.” As such, hand radiation exposure was higher in the first assistant than in the surgeon. This study concluded that exposure to radiation during this type of procedure is below the current recommended limits.

In a 2006 paper, Bahari et al.17 collected radiation exposure data during percutaneous wiring of the fingers, hand, and wrist in 30 cases. Dosimeters were located on the dorsal aspect of the dominant hand and on the thyroid (beneath the lead apron in 15 cases and above the lead apron in 15 cases). There was a significant difference (p < 0.05) between radiation exposure in the shielded and unshielded thyroid groups. The first assistant's role was to maintain position and reduction and, accordingly, he or she had higher radiation exposure than the primary surgeon. This study concluded that when a person is appropriately shielded, radiation exposure to the hand and the thyroid is within recommended limits.

In a 2003 study, Tasbas et al.18 documented radiation exposure in 107 consecutive orthopaedic cases over a 3‐month period. These cases included both portable radiographic and fluoroscopic imaging. Portable radiography was used in all 107 cases, and fluoroscopy was used in 44 cases; unfortunately, data were not separated out by type of imaging. However, because Nelson et al.10 showed that radiation exposure is higher with portable radiography than with C‐arms/fluoroscopy, we included the data in this review. Dosimeters were worn under lead aprons and on the shoulder. The surgeon was positioned >90 cm from the surgical field during imaging, and the first assistant was approximately 10 cm away on average; therefore, the first assistant had higher radiation exposure than the surgeon. This study concluded that the risk of radiation exposure is higher for the assistant surgeon; however, with the correct PPE, radiation exposure is within established limits.

In an article that was published in 1998, Müller et al.19 measured radiation exposure to the hand of the operating surgeon and first assistant during 41 intramedullary nailing procedures (30 tibiae, 21 of which were unreamed, and 11 femora, 4 of which were unreamed). A dosimeter ring was placed on the dominant ring finger. This study assumed that the limiting body part for radiation exposure is the hand, and concluded that >400 cases would have to be performed annually to approach the recommended radiation limits.

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Discussion

This systematic review examined the available literature addressing the amount of radiation exposure received by PAs/first assistants in the orthopaedic operating room. Depending on a PA's role and position during orthopaedic operations, he or she may be at greater risk of exposure to radiation than the primary surgeon. In the studies presented here, 3 found first assistants at greater risk16–18, 6 found surgeons at greater risk10–15, and 1 was mixed, depending on the location of the dosimeters19. In 2012, a systematic review of radiation exposure to operating surgeons concluded that it is unlikely that the primary surgeon will reach the annual limits of radiation exposure20. Based on our systematic review, there is a large variation in radiation exposure to first assistants; however, it does appear that with the use of proper PPE and radiation safety precautions, it is unlikely that a PA will reach the annual limits of exposure set by both the NCRP and the ICRP.

This review consistently shows that use of proper PPE (e.g., a lead apron and a thyroid shield), along with increasing distance from the source of radiation, limited exposure, and utilization of barriers and proper technique, can decrease radiation exposure. With proper PPE and the implementation of radiation safety measures, the limiting body part for an orthopaedic PA's radiation exposure is the hands. This is somewhat expected since the hand has been shown to be the limiting factor in orthopaedic surgeons21. This is most likely because the fingers or hand are exposed to the primary beam during surgery. In 1 study, it was shown that the surgeon's hand can be caught in the primary beam in approximately 15% of surgeries22. If a hand of the surgical team enters the primary beam, radiation exposure can be up to 100 times higher than the exposure received just 15 cm away from the primary beam23

Although the calculated data from Mehlman and DiPasquale11 showed that the annual recommended radiation limit for the eye would be reached with only 67 surgical cases performed from the first assistant's position without use of PPE, this finding differed substantially from other available studies. Three other studies10,13,16 included in this review determined that a substantially higher number of cases would need to be performed in order to reach exposure limitations, ranging from 667 cases16 to an infinite amount13. The Mehlman and DiPasquale paper described a Level‐V study (the lowest level of included study); 2 of the studies suggesting higher case numbers would need to be performed before the limits are reached had higher levels of evidence. None of the studies included in this review had surgeons or assistants who used lead glasses as a form of PPE; the findings of Mehlman and DiPasquale may suggest that routine inclusion of lead glasses can benefit providers positioned closest to the surgical field.

Müller et al.19 found that annual allowable radiation dosage to the hand would likely be reached after 421 cases had been performed (the smallest number of cases needed to reach extremity exposure limits for the hand in the reviewed studies). This is in contrast to studies (e.g., the one by Khan et al.16) that showed that allowable limits for the hand would not be reached until 3,847 cases had been performed. Certainly, the case limit numbers referred to in this review would be highly dependent on the quantity of fluoroscopy used during each case (which varies with different types of cases) and on the amount of time that the provider is spending with his or her hands directly in the path of the primary beam. At a minimum, the findings by Müller et al. raise the question of whether or not routine use of leaded hand protection should also be included as PPE for providers whose hands may be exposed to the primary beam.

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Limitations

One of the limitations of this systematic review is that it is difficult to combine the data from each of the included studies because of the variety of surgery types and the different locations of the dosimeters. Of the 8 human studies included in this review, 5 were extremely limited in the description of type of surgery/surgeries performed (those by Palácio et al.15, Khan et al.16, Bahari et al.17, Alonso et al.12, and Müller et al.19), and only 2 studies included all procedures in which fluoroscopy was used (those by Tasbas et al.18 and Riley13). Additionally, there is a lack of standardization among the studies with regard to the timing and the technique of dosimeter evaluation. Also, the calibration of the C‐arms used in many of the studies is unknown.

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Conclusions

This systematic review has reinforced that PPE (e.g., lead aprons and thyroid shields) substantially decreases the amount of radiation exposure to PAs and primary surgeons in the orthopaedic operating room. Although it appears that PAs would be very unlikely to reach the annual limits recommended by the NCRP and the ICRP, additional long‐term studies could be done to evaluate radiation exposure in all orthopaedic fluoroscopic procedures and to different anatomical locations, both shielded and unshielded. Regardless of the findings of this review or any future studies, until the consequences of exposure to chronic, low‐level radiation are known, PAs and other operating room staff should continue to reduce radiation exposure to as low as reasonably achievable.

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