Clinical Orthopaedics and Related Research®

Clin Orthop Relat Res DOI 10.1007/s11999-014-3503-3

A Publication of The Association of Bone and Joint Surgeons®

SYMPOSIUM: MINIMALLY INVASIVE SPINE SURGERY

Does Less Invasive Spine Surgery Result in Increased Radiation Exposure? A Systematic Review Elizabeth Yu MD, Safdar N. Khan MD

Ó The Association of Bone and Joint Surgeons1 2014

Abstract Background Radiation exposure to patients and spine surgeons during spine surgery is expected. The risks of radiation exposure include thyroid cancer, cataracts, and lymphoma. Although imaging techniques facilitate less invasive approaches and improve intraoperative accuracy, they may increase radiation exposure. Questions/purposes We performed a systematic review to determine whether (1) radiation exposure differs in open spine procedures compared with less invasive spine procedures; (2) radiation exposure differs in where the surgeon is positioned in relation to the C-arm; and (3) if radiation exposure differs using standard C-arm fluoroscopy or fluoroscopy with computer-assisted navigation. Methods A PubMed search was performed from January 1980 to July 2013 for English language articles relating to radiation exposure in spine surgery. Twenty-two relevant articles met inclusion criteria. Level of evidence was assigned on clinical studies. Traditional study quality evaluation of nonclinical studies was not applicable. Results There are important risks of radiation exposure in spine surgery to both the surgeon and patient. There is Each author certifies that he or she, or a member of his or her immediate family, has no funding or commercial associations (eg, consultancies, stock ownership, equity interest, patent/licensing arrangements, etc) that might pose a conflict of interest in connection with the submitted article. All ICMJE Conflict of Interest Forms for authors and Clinical Orthopaedics and Related Research editors and board members are on file with the publication and can be viewed on request. E. Yu (&), S. N. Khan Division of Spine Surgery, Department of Orthopaedics, The Ohio State University Wexner Medical Center, 725 Prior Hall, 376 West 10th Avenue, Columbus, OH 43210, USA e-mail: [email protected]; [email protected]

increased radiation exposure in less invasive spine procedures, but the use of protective barriers decreases radiation exposure. Where the surgeon stands in relation to the image source is important. Increasing the distance between the location of the C-arm radiation source and the surgeon, and standing contralateral from the C-arm radiation source, decreases radiation exposure. The use of advanced imaging modalities such as CT or three-dimensional computerassisted navigation can potentially decrease radiation exposure. Conclusions There is increased radiation exposure during less invasive spine surgery, which affects the surgeon, patient, and operating room personnel. Being cognizant of radiation exposure risks, the spine surgeon can potentially minimize radiation risks by optimizing variables such as the use of barriers, knowledge of position, distance from the radiation source, and use of advanced image guidance navigation-assisted technology to minimize radiation exposure. Continued research is important to study the longterm risk of radiation exposure and its relationship to cancer, which remains a major concern and needs further study as the popularity of less invasive spine surgery increases.

Introduction Intraoperative imaging and surgical approaches have evolved in tandem in spine surgery. In general, surgeons seek to minimize tissue trauma using less invasive approaches, but these approaches sometimes call for more image guidance, most commonly with fluoroscopy, than do open approaches. This may also increase radiation exposure because the use of fluoroscopy remains necessary to assist in confirming vertebral levels, checking spinal alignment, and guiding implant placement [17].

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Yu and Khan

Clinical Orthopaedics and Related Research1

Spine surgeons, being at the front line in the operating room to ionizing radiation, need to have a general understanding of the magnitude of radiation dose from the use of fluoroscopic equipment and how to minimize radiation exposure. The delayed radiation exposure effect from this type of exposure is not trivial [25, 28, 34]. In 2005, Mastrangelo [19] reported orthopaedic surgeons have a fivefold increase in their lifetime of cancer rates compared with nonorthopaedic surgeons in a hospital setting. We therefore sought to perform a systematic review on radiation exposure in spine surgery. Our specific goals were to determine whether (1) radiation exposure differs in open spine procedures compared with less invasive spine procedures; (2) radiation exposure differs in where the surgeon is positioned in relation to the C-arm; and (3) if radiation exposure differs in using standard C-arm fluoroscopy or fluoroscopy with computer-assisted navigation.

Search Strategy and Criteria A PubMed search was performed using the keywords ‘‘radiation’’, ‘‘exposure’’, ‘‘spine’’, ‘‘spinal’’, ‘‘surgery’’, ‘‘patient’’, ‘‘surgeon’’, and ‘‘orthopaedics’’ from January 1980 to July 2013. The keywords were limited to the title and/or the abstract. Results yielded 254 articles. When limited to the English language, 238 articles were included. Each study was scrutinized by the first author (EY) and was included if the authors of the study (1) quantified radiation exposure; (2) measured radiation exposure; and/ or (3) discussed radiation exposure risks in relation to adult spine surgery. Studies were excluded if radiation exposure was not assessed, radiation exposure was assessed but quantification was unclear, or if radiation exposure was assessed outside of the operating room. A total of 22 studies met inclusion (Fig. 1). The references cited in each included article were reviewed and studies were added if any met the inclusion criteria. Review articles were included. Information obtained from the literature included patient age, open and less invasive spine procedure performed, number of levels performed, amount of fluoroscopy time, and amount of radiation exposure to the surgeon and/or patient and/or room. How each author objectively calculated radiation exposure was assessed. Studies included both controlled and noncontrolled studies of spine procedures to include open or less invasive procedures. Level of evidence was assigned to each article where this applied [38]. Traditional quantification of clinical studies cannot be performed because the variability of studies conducted ranged from patient studies to cadaveric

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Fig. 1 The flow chart shows the results of the literature search.

models to anthropomorphic models that mimic the human body, also known as phantoms. Spine surgeons should have knowledge of the basic units for quantifying ionizing radiation to understand radiation exposure. Radiation dose from fluoroscopic use is measured in two ways, the direct dose and the effective dose. The direct dose is the dose delivered to the skin or organ from the ionizing radiation measured in milliGrays. Radiation injuries to the skin from fluoroscopy are always located on the xray tube side of the body. The effective dose is the dose related to relative risk of cancer measured in Sieverts. It allows for comparison across different imaging modalities and distribution across the body. The Sievert replaces the traditional unit of rem (radiation equivalent in humans), whereby 1 Sv equals 100 rem [35]. For basic understanding of direct dose and effective dose, a single posterior anterior chest radiograph delivers a direct skin dose of 0.14 Gy to the posterior chest. The effective dose, multiplied by the weighted factor, is 0.03 mSv. A chest CT dose is 7 mSv [4, 20]. A lumbar radiograph is 1.5 mSv and lumbar CT is 15 mSv [9]. Maximum dose of radiation exposure is regulated nationally and internationally and must be understood by the spine surgeon, who may be exposed daily to radiation.

Radiation Exposure in Spine Surgery: A Systematic Review

Results Open Compared With Less Invasive Procedures: Fluoroscopy Radiation exposure is greater with less invasive spine procedures compared with open spine procedures. Four studies assess radiation exposure with and without use of protective equipment in open versus less invasive spine procedures (Table 1). The highest level of evidence of these articles was Level 2. Bronsard et al. [3] performed a retrospective observational study assessing radiation exposure in lumbar fractures treated with the open technique and percutaneous technique. There was significantly increased radiation time and radiation exposure up to three times to the patient with the percutaneous approach. Mariscalco et al. [18] assessed radiation exposure in a prospective study comparing open and less invasive microdiscectomies. The surgeon wore dosimeters outside the lead protection in less invasive microdiscectomies and without lead protection on open microdiscectomies. There was significant increase in radiation exposure to the thyroid, chest, and hand with the less invasive procedure. Fransen [5] prospectively gathered radiation dose and exposure time from various spine procedures to include anterior cervical fusion, anterior cervical disc replacement, vertebroplasty, kyphoplasty, posterior lumbar interbody fusion, percutaneous lumbar fusion, and percutaneous interspinous process device. Fluoroscopic time for open pedicle screw placement was 44 seconds per procedure and 8 seconds per screw. Percutaneous pedicle screw placement was 145 seconds per procedure and 27 seconds per screw. The average radiation exposure per screw was 3.2 times higher when performed percutaneously as compared with the open procedure. Wang et al. [37] prospectively followed 85 patients who underwent single-level open or less invasive transforaminal lumbar interbody fusions (TLIF) for degenerative or isthmic spondylolithesis. Average fluoroscopic time for the open TLIF was 37 seconds and for the less invasive TLIF was 84 seconds.

Location of Surgeon in the Operating Room Where the surgeon stands in relation to the C-arm image source is important. Standing contralateral to the imaging source decreases radiation exposure (Fig. 2). Increasing the distance between the surgeon and the radiation source decreases radiation exposure. Ionizing radiation follows the inverse square law where increasing the distance from the radiation source by two decreases radiation exposure by

four. A total of seven studies assesses the position of the surgeon and of the radiation source. The highest level of evidence of the articles was 4 (Table 2), although only one of these articles could be graded on the level of evidence rubric. Singer [30] reported increasing the distance from the radiation source decreases the surgeon’s radiation exposure. Giordano et al. [7] assessed the use of standard C-arm fluoroscopy on cervical spine imaging and describe three scenarios to measure radiation exposure to the patient and the surgeon using cadaveric models and surrounding dosimeters. The authors concluded the highest amount of radiation exposure to the patient is closest to the imaging source. Mulconrey [24] placed dosimeters on operating room personnel and on the operating table for lumbar spine procedures. The lowest radiation exposure was found farthest from the radiation source, the cranial portion of the table. Mehlman and DiPasquale [21] placed dosimeters on anthropomorphic models mounted where operating room personnel would be. The authors concluded radiation exposure to operating room personnel is decreased with increased distance from the radiation source; specifically, greater than 36 inches has the lowest amount of radiation. Rampersaud et al. [26] studied six cadavers and measured radiation exposure to the surgeon’s neck, torso, and dominant hand. The authors reported a dramatic decrease in radiation exposure when the surgeon stood on the contralateral side of the patient as the image source. Jones et al. [11] used anthropomorphic phantom models assessing surgeon radiation exposure with the C-arm image source in the superior or inferior position and reported increased radiation on the same side as the radiation source. Lee et al. [16] measured scattered radiation dose using a C-arm on an anthropomorphic model with the dosimeter placed at 45° increments around the model. The C-arm was placed in four configurations and the surgeon turned their head away and reported similar findings.

Use of the Standard C-arm Fluoroscopy Compared With Fluoroscopic Imaging with Computer-assisted Navigation Incorporation of advanced imaging with computer navigation assistance to aid in challenging musculoskeletal anatomy can decrease radiation exposure to the patient and staff. Eleven studies assessed the types of imaging guidance used in spine surgery and radiation exposure (Table 3). The highest level of evidence of the studies was 2. Various imaging modalities are available, including a standard C-arm, mini-C-arm, CT, and three-dimensional (3-D) reconstructed C-arm. The cone-beam CT such as the

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Comparison Between Percutaneous and Traditional Fixation of Lumbar Spine Fracture: Intraoperative Radiation Exposure Levels and Outcomes

Radiation Exposure to the Surgeon During Open Lumbar Microdiscectomy and Minimally Invasive Microdiscectomy: A Prospective, Controlled Trial

Fluoroscopic Exposure in Modern Spine Surgery

Comparison of One-level Minimally Invasive and Open Transforaminal Lumbar Interbody Fusion in Degenerative and Isthmic Spondylolithesis Grades 1 and 2

Bronsard [3] (2013)

Mariscalco [18] (2011)

Fransen [5] (2011)

Wang [37] (2010)

VAS = visual analog scale; ODI = Oswestry Disability Index.

Title

Study (first author)

A prospective study assessing total radiation dose and exposure time in 17 anterior cervical discectomy and fusion (ACDF) cases, 11 cervical disc replacement cases, 4 vertebroplasty cases, 12 kyphoplasty cases, 28 posterior lumbar interbody fusion cases, 3 percutaneous lumbar fusion cases, and 20 percutaneous insertions of an interspinous process device. There was 10.3 seconds of fluoroscopy per case ACDF case, 24.3 seconds of fluoroscopy per cervical disc replacement case, 44 seconds per open posterior lumbar interbody fusion case, 85 seconds per vertebroplasty case, 115 seconds per percutaneous interspinous device case, 125 seconds per percutaneous fusion case, and 301 seconds per kyphoplasty case. Fransen concluded percutaneous lumbar fusions yielded 3 times more fluoroscopy than open lumbar fusions. A prospective study comparing single-level open transforaminal lumbar interbody fusion (TLIF) with less invasive TLIF in 46 patients with degenerative spondylolisthesis and 39 patients with isthmic spondylolisthesis. Forty-two patients underwent less invasive TLIF and 43 patients underwent an open TLIF with a mean age of 51.7 years. Average followup was 26 months with similar pre- and postoperative VAS and ODI. Average fluoroscopic time was 84 seconds for the less invasive and 37 seconds for the open TLIF. Operative time was similar for both. Intraoperative blood loss, average hospital stay, and fluoroscopic time were statistically significant between each group.

A prospective cohort study assessing radiation exposure in 10 patients undergoing open lumbar microdiscectomy compared with 10 patients undergoing less invasive microdiscectomy. Dosimeters were placed on the outside of the thyroid, chest, and distal forearm. Mean radiation exposure to the thyroid, chest, and hand was statistically greater in the less invasive than in the open procedure. They were nearly 10 to 20 times greater. Positioning adjacent to the radiation source statistically increased radiation exposure to the chest.

A retrospective observational review of percutaneous screw placement in thoracolumbar spine fractures was performed. A total of 60 patients were studied. The average age was 42 years (range, 15–66 years). There were 33 males and 27 females with an average fluoroscopic time in the percutaneous procedure of 2.33 minutes and 0.49 minutes with the open procedure. There was an average per case radiation exposure of 151 mRem with the closed procedure and 55 mRem with the open procedure.

Summary of article

Table 1. Summary table of articles: open compared with less invasive procedures

Prospective cohort study

Prospective observational study

Prospective cohort study

Retrospective observational study

Study design

2

4

2

3

Level of evidence

Yu and Khan Clinical Orthopaedics and Related Research1

Radiation Exposure in Spine Surgery: A Systematic Review

Fig. 2 The image represents the intraoperative location of the surgeon and assistant with the fluoroscopy in the translateral position. The black arrow is the image source and the red arrows represent scatter. The surgeon should stand contralateral to the radiation source, which would be on the right of the image.

O-arm generates an intraoperative CT image. The 3-D reconstructed C-arm such as the Iso C-arm is a modified Carm that rotates around the patient and constructs a CT-like image. Each equipment generates differing amounts of radiation. Giordano et al. [7, 8] measured radiation exposure using the standard C-arm and mini-C-arm to the patient and surgeon imaging the cadaveric cervical spine. Patient exposure was not necessarily reduced with either image. Surgeon radiation exposure was less with the miniC-arm. Gebhard et al. [6] performed a prospective study of patients who underwent cervical, thoracic, or lumbar spine fracture fixation with pedicle screws through CT computerassisted navigation, Iso C-arm computer-assisted navigation, or standard C-arm placement. Radiation exposure to the patient was decreased with the use of Iso C-arm computer-assisted surgery. Slomcykowski et al. [31] used an optimized CT protocol on phantom models and found decreased radiation exposure to the patient compared with two other CT protocols used. This provided detailed visualization of anatomical structures. Radiation exposure was higher than fluoroscopic techniques. Bandela et al. [2] assessed radiation exposure to the patient and operating room personnel using a cadaveric model and dosimeters comparing fluoroscopic screw placement and CT-guided navigation screw placement. Abdullah et al. [1] calculated average surgeon radiation exposure of 44.22 microRem at a distance of 4.5 m from the CT O-arm image. Lange et al. [15] used an anthropomorphic model to assess radiation exposure in a small and large patient with intraoperative CT with navigation. They concluded the amount of radiation to the patient is less than an abdominal CT scan. Zhang et al. [39] studied anthropomorphic models undergoing CT O-arm images and standard 64-slice body CT. There was a

50% decrease in radiation exposure to the patient with the O-arm images; however, exposure scatter was higher with the O-arm. Kraus et al. [13] assessed radiation exposure to patients who underwent lumbar fracture stabilization and patients who underwent transsacral screw stabilization with the standard fluoroscopy or 3-D reconstructed computerassisted navigation. Radiation exposure was decreased to the patients with the use of 3-D reconstructed computerassisted navigation. Smith et al. [32] studied cadaveric pedicle screw placement using standard C-arm fluoroscopy and Iso C-arm computer-assisted guidance. Radiation exposure was reduced with the use of the computer-assisted image guidance system. Kim et al. [12] assessed radiation exposure in less invasive TLIF with instrumentation with standard C-arm fluoroscopy and 3-D reconstructed computer-assisted navigation. Radiation exposure was decreased to the patient with navigation. Refer to Table 3 for a detailed summary of articles.

Discussion Radiation exposure affects both patients and surgeons, and careless use can result in illness and injury to patients and providers alike [25, 28, 34]. As spine surgeons seek to minimize soft tissue injury by using less invasive surgical approaches, the use of fluoroscopy and other imaging tools may increase radiation exposure. This systematic review sought to determine whether (1) radiation exposure differs in open spine procedures compared with less invasive spine procedures; (2) radiation exposure differs in where the surgeon is positioned in relation to the C-arm; and (3) if radiation exposure differs in using the standard C-arm fluoroscopy or advanced image-guided fluoroscopic computer-assisted navigation. This study had a number of limitations. The limitations included: (1) the limited number of high-quality level of evidence and variability of radiation exposure to the surgical staff among the articles available in the literature; and (2) the variability in the amount of radiation exposure between studies may be attributed to each surgeon’s skills and each surgeon’s comfort level. These limitations emphasize the importance of cohort studies to have a comparison group and the need for future studies. Continued research is important to study the long-term risk of radiation exposure and its relationship to cancer, which remains a major concern and needs further study as the popularity of less invasive spine surgery increases. In addition, there is likely to be some variability in the amount of radiation exposure in the various included studies that can be attributed to individual surgeons’ skills and comfort levels with the various procedures. This is likely to be very

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Title

Cervical Spine Imaging Using Standard C-arm Fluoroscopy: Patient and Surgeon Exposure to Ionizing Radiation

Occupational Radiation Exposure to the Surgeon

Fluoroscopic Radiation Exposure in Spinal Surgery In Vivo Evaluation for Operating Room Personnel

Radiation Exposure to the Orthopaedic Surgical Team During Fluoroscopy: How Far Away Is Far Enough?

Study (first author)

Giordano [7] (2008)

Singer [30] (2005)

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Mulconrey [24] (2013)

Mehlman [21] (1997)

An anthropomorphic phantom model using two fluoroscopic machines with the source in the superior position of an AP image. Dosimeter badges were placed at the neck and chest level, both protected and unprotected. Varying distances were then used at 12 inches for the surgeon, 24 inches for the first assistant, 36 inches for the scrub nurse, and 60 inches for the anesthesiologist. Radiation exposure was read at 1-, 2-, 3-, 5-, and 10-minute intervals. The authors concluded low radiation exposure was seen at 36 inches or greater. High radiation exposure was seen at 24 inches or less.

A prospective clinical study assessing radiation exposure in 35 patients undergoing spine procedures to include anterior cervical decompression and fusions (ACDFs), posterior lumbar fusions, transforaminal lumbar interbody fusion (TLIF), and lumbar decompressions. Average age was 52 years with 13 lumbar decompressions, 2 posterior lumbar fusions, 16 TLIFs, and 4 ACDF. Dosimeters were placed at the caudal and cranial operating room table and on the unprotected surgeon and first assistant’s chest. The assistant surgeon stood a minimum of 3 feet away from the radiation source. The surgeon intermittently stood away from the radiation source. The surgeon’s radiation exposure was 1225 mRem, first assistant was 369 mRem, cranial table 92 mRem, and caudal table 150 mRem. Increasing the distance from the radiation source decreases radiation exposure.

A review of radiation exposure to the orthopaedic surgeon in orthopaedic procedures was investigated. This included intramedullary rodding, hand exposure with the C-arm and mini-C-arm, and radiation exposure to the operating room personnel. Methods to decrease radiation exposure include increasing the distance from the beam, shielding from the beam, a low-dose option, beam collimation, and surgeon control of fluoroscopy.

A cadaveric specimen was surrounded by 13 dosimeters where 4 were placed at 90° superior to the specimen, inferior to the specimen, and 1 inch from the specimen at the same plane of the specimen. One dosimeter was placed at the center on the specimen. The C-arm image source was placed at the specimen, 10 inches from the specimen and image intensifier against the specimen. Decreased distance from the specimen and radiation source increased radiation exposure to the specimen. Greatest surgeon radiation exposure was at the dosimeters on the image source side.

Summary of article

Table 2. Summary table of articles: location of surgeon in the operating room

Phantom observational study

Prospective study

Review

Cadaveric study

Study design

4

Level of evidence

Yu and Khan Clinical Orthopaedics and Related Research1

Title

Radiation Exposure to the Spine Surgeon During Fluoroscopically Assisted Pedicle Screw Insertion

Radiation Exposure During Fluoroscopically Assisted Pedicle Screw Insertion in the Lumbar Spine

Measurements of Surgeons’ Exposure to Ionizing Radiation Dose During Intraoperative Use of C-arm Fluoroscopy

Study (first author)

Rampersaud [26] (2000)

Jones [11] (2000)

Lee [16] (2012)

Table 2. continued

An anthropomorphic whole-body model composed of human bones and simulated soft tissue was used to measure scatter radiation exposure with dosimeters placed at 45° increments around a chest anthropomorphic model as well as at 4 distances: 40 cm, 60 cm, 80 cm, and 100 cm. Dosimeters were placed at the eyes, thyroid, breast, and gonads. The C-arm was placed in 4 different positions: image source superior, image source inferior, translateral, and another translateral. The authors noted decreased scatter radiation exposure with increased distance from the fluoroscopy, rotating the head away decreased radiation exposure to the thyroid and eyes with the C-arm source inferior or contralateral to the surgeon.

An anthropomorphic model was placed prone on a radiolucent table. Radiation exposure was measured with the C-arm positioned with the image source superior and image intensifier inferior and vice versa. Dosimeter readings were conducted in the beam, 5 cm, 20 cm, 25 cm, and 50 cm away, knees, gonads, eyes, and thyroid. Superior source C-arm with pedicle screw placement has 2.3-mSv patient radiation exposure per case compared with a 30-cm working distance with an inferior source C-arm of 6.9-mSv radiation exposure per case. There is greater surgeon radiation exposure to the eyes and thyroid with the superior image source and greater radiation exposure to the gonads and knees with the inferior image source.

6 cadaveric torso specimens underwent T11 to S1 pedicle screw placement under fluoroscopic guidance. Dosimeters were placed on the unprotected thyroid, protected waist, the surgeon on the image source side unprotected dorsal and ventral waist, the surgeon on the image intensifier side unprotected ventral and dorsal waist, and a control subject in a nonradiated room. Ring dosimeters were used. Ionizing radiation was measured at 10cm increments surrounding the L4–5 cadaveric torso level on the image intensifier and image source side cephalad, midline, and caudal to L4–5. The greatest radiation exposure was found to be directly ipsilateral to the image source in the torso and hand. Larger cadaveric weight specimens also increased radiation exposure.

Summary of article

Phantom observational study

Phantom study

Cadaveric study

Study design

Level of evidence

Radiation Exposure in Spine Surgery: A Systematic Review

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123

Cervical Spine Imaging Using Mini-CA cadaveric specimen was surrounded by 13 dosimeters where 4 were placed at Cadaveric study arm Fluoroscopy: Patient and Surgeon 90° superior to the specimen, inferior to the specimen, and 1 inch from the Exposure to Direct and Scatter specimen at the same plane of the specimen. One dosimeter was placed at the Radiation center on the specimen. The mini-C-arm image intensifier was placed closest to the specimen. Specimen radiation exposure was not reduced with mini-Carm use. Surgeon exposure was lower than reported C-arm exposure.

Does Computer-assisted Spine Surgery Reduce Intraoperative Radiation Doses?

Radiation Dose for Pedicle Screw An anthropomorphic phantom study composed of synthetic material and real Phantom cohort study Insertion: Fluoroscopic Method versus human skeleton to mimic a human torso was composed to assess radiation Computer-assisted Surgery exposure with percutaneous pedicle screw placement with fluoroscopically and intraoperative CT with computer-assisted navigation with 3 different settings. Dosimeters were placed within the phantom at respective organs. The effect dose with fluoroscopy was 1.0; optimized CT was 2.4 mSv. Organ dose was lowest for a majority of organs with fluoroscopy compared with optimized CT. The authors concluded intraoperative CT with computerassisted navigation improves visualization with increased radiation and should be used prudently.

Use of CT-based Intraoperative Spinal A cadaveric study was performed to assess radiation exposure with the Cadaveric study Navigation: Management of Radiation placement of pedicle screws from T7 to S1 on the left side and use of CT Exposure to Operator, Staff, and navigation (O-arm) on the right side. Dosimeters were placed on and within Patients the cadaver over the eye, thyroid, chest, and abdomen. Dosimeters were placed on the surgeon over the eyes, protected thyroid, protected chest, protected abdomen and pelvis, and protected hands. Another protected dosimeter was placed at the head of the bed. Dosimeters were then placed around the O-arm at 1-m distances from the operating room table. Patient radiation exposure was greater with CT navigation compared with fluoroscopy. Positioning perpendicular to the patient at the control panel of the O-arm decreased radiation exposure.

Giordano [8] (2009)

Gebhard [6] (2006)

Slomczykowski [31] (1999)

Bandela [2] (2013)

A prospective clinical study enrolled 38 patients who underwent cervical, Prospective cohort study thoracic, or lumbar spine surgery with instrumentation. Standard C-arm fluoroscopy, two-dimensional C-arm-based navigation, CT navigation, and Iso C-arm navigation was used. Dosimeters were used to measure radiation on the patient, at the image source and image intensifier. The Iso C-arm with navigation had the least radiation exposure of 152 mGy compared with 1091 mGy in the standard C-arm fluoroscopy.

A cadaveric specimen was surrounded by 13 dosimeters where 4 were placed at Cadaveric study 90° superior to the specimen, inferior to the specimen, and 1 inch from the specimen at the same plane of the specimen. One dosimeter was placed at the center on the specimen. The C-arm image source was placed at the specimen, 10 inches from the specimen and image intensifier against the specimen. Decreased distance from the specimen and radiation source increased radiation exposure to the specimen. Greatest surgeon radiation exposure was at the dosimeters on the image source side.

Cervical Spine Imaging Using Standard C-arm Fluoroscopy: Patient and Surgeon Exposure to Ionizing Radiation

Study design

Giordano [7] (2008)

Summary of article

Title

Study (first author)

Table 3. Summary table of articles: use of the standard C-arm fluoroscopy compared with fluoroscopic imaging with computer-assisted navigation

2

Level of evidence

Yu and Khan Clinical Orthopaedics and Related Research1

Dosimeter Characterization of a Conebeam O-arm Imaging System

A prospective cohort study assessing fluoroscopic time among 20 different Prospective cohort study patients with lumbar fractures who underwent lumbar instrumentation with fluoroscopy with and without three-dimensional computer-assisted navigation and 20 patients who underwent percutaneous transsacral screw with fluoroscopy and three-dimensional computer-assisted navigation. Two retrospective patients were used for the fluoroscopic-only comparison transsacral screw group. An anthropomorphic model was used to assess radiation exposure for each procedure. Dosimeters were placed within the model. Statistically significant increases in fluoroscopic time were seen with nonnavigated lumbar fusion at 105 seconds compared with 72 seconds. Radiation exposure was 5.03 mSv compared with 0.4 mSv, respectively. Increased radiation time and exposure was seen with the fluoroscopically guided transsacral screw compared with three-dimensional navigation group.

Anthropomorphic models were used to assess radiation exposure with the use of Phantom study intraoperative CT, O-arm, compared with standard 64-slice body CT. The authors concluded there was a 50% reduction in patient radiation exposure with the O-arm compared with standard 64-slice body CT.

Smith [32] (2008) Comparison of Radiation Exposure in A cadaveric study of 4 specimens with a mean age of 71.5 years was used to Cadaveric comparison study Lumbar Pedicle Screw Placement with assess radiation exposure in pedicle screw placement with C-arm fluoroscopy Fluoroscopy versus Computer-assisted in 2 specimens and three-dimensional reconstructed Iso-C arm with computerImage Guidance with Intraoperative assisted navigation in 2 specimens. Dosimeters were placed on the Three-dimensional Imaging unprotected thyroid, waist, and ring of the surgeon. Statistically significant radiation exposure to the waist with the C-arm was 4.33 mRem compared with 0.33 mRem with the Iso-C arm per single-level procedure. Mean thyroid exposure was 0.33 mRem and 0.66 mRem, respectively. Ring exposure was below the measurable threshold for both groups.

Kraus [13] (2010) Can Computer-assisted Surgery Reduce the Effective Dose for Spinal Fusion and Sacroiliac Screw Insertion?

Zhang [39] (2009)

Lange [15] (2013) Estimating the Effective Radiation Dose An anthropomorphic spine model composed of plastic and foam was used to Observational study Imparted to Patients by Intraoperative assess radiation exposure from a cone-beam CT scan or O-arm. Dosimeters Cone-beam Computed Tomography in were placed on the model and 3 m from the O-arm isocenter at 45° Thoracolumbar Spinal Surgery increments. Scans were performed in the small patient setting and large patient setting. Patient radiation exposure in the small patient setting was 3.24 mSv compared with 8.09 mSv for the large patient. Average abdominal CT scans is 1–31 mSv.

Radiation Exposure to the Spine Surgeon A prospective study to assess radiation exposure to the surgeon in 10 patients Prospective study in Lumbar and Thoracolumbar Fusions who underwent thoracolumbar or lumbar instrumented fusions with the use of With the Use of Intraoperative the CT with navigation. The mean patient age was 51.7 years and mean body Computed Tomographic 3mass index was 31.5 kg/m2. A dosimeter was placed on the unprotected surgeon’s chest. The average radiation exposure was 44.22 microRem with a Dimensional Imaging Systems mean distance of 4.5 m.

Study design

Abdullah [1] (2012)

Summary of article

Title

Study (first author)

Table 3. continued

2

4

4

Level of evidence

Radiation Exposure in Spine Surgery: A Systematic Review

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Clinical Orthopaedics and Related Research1

3 Use of Navigation-assisted Fluoroscopy Two study arms were created to assess less invasive transforaminal lumbar Prospective study with to Decrease Radiation Exposure During interbody fusion (TLIF) with and without computer-assisted navigation, a retrospective cohort group Minimally Invasive Spine Surgery cadaveric arm and clinical arm. Nine cadaveric TLIFs were performed with navigation-assisted fluoroscopy and 9 TLIFs with fluoroscopy measuring fluoroscopic time, radiation exposure, and surgical time. Dosimeters were placed at the unprotected thyroid. Fluoroscopy time was statistically greater with the fluoroscopy group than the navigation with fluoroscopy group. Surgical time was similar. Radiation exposure was undetectable with the navigation group and 12.4 mRem for the fluoroscopy group. The second arm included a prospective study of 10 patients undergoing a less invasive TLIF with fluoroscopy and computer-assisted navigation with 8 case-matched retrospective patients who underwent a less invasive TLIF with fluoroscopy. Fluoroscopy time was statistically greater with the fluoroscopy group at a mean of 147 seconds compared with the navigation group with a mean of 57 seconds. Kim [12] (2006)

Table 3. continued

Summary of article

Study design Title Study (first author)

Level of evidence

Yu and Khan

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hard to characterize and may always represent an area of uncertainty in studies on this topic. We found that radiation exposure was higher during procedures using less invasive spine approaches than an open approach. The use of protective barriers, to include a lead apron, thyroid shield, lead glasses, and lead gloves, can decrease the exposure [10, 14, 22, 23, 33, 36]. When the surgeon was positioned on the side contralateral to the C-arm radiation source, radiation exposure to the surgeon was lower (Fig. 2). The greater distance the surgeon is from the radiation source, the lower the radiation exposure to the surgeon. This can be applied to operating room personnel. Judicious use of advanced imaging, to include CT or 3-D reconstructed C-arm images with computer-assisted navigation, can decrease radiation exposure to the surgeon and operating room personnel as well as improve visualization of the patient’s anatomy. Intraoperative CT with computerassisted navigation does result in increased radiation exposure to the patient compared with standard C-arm fluoroscopy; however, it is less than with standard CT. With the regulation passed by the National Council on Radiation Protection and Measurements, it is important to be cognizant of radiation exposure and to practice safe surgery. The Council recommends an annual radiation exposure limit for occupational category of 50 mSv or 5 rem per year [29]. The International Commission on Radiation Protection recommends an annual and peak exposure limit of 20 mSv or 2 rem for a 5-year average [27]. By understanding the factors and variables affecting radiation risks, the spine surgeon can provide guidance and a leadership role in the operating room by controlling variables such as distance, location, the use of barriers, exposure time, and advanced imaging techniques. By being cognizant of radiation exposure risks, the action by the spine surgeon can affect positively many lives by potentially minimizing both the immediate and delayed effects of ionizing radiation not only to the spine surgeon in particular, but also to the patient and the rest of the operating room personnel.

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