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Scientific Articles   |    
Patient and Surgeon Radiation Exposure: Comparison of Standard and Mini-C-Arm Fluoroscopy
Brian D. Giordano, MD1; Judith F. Baumhauer, MD1; Thomas L. Morgan, PhD1; Glenn R. RechtineII, MD1
1 Department of Orthopaedics and Rehabilitation (B.D.G., J.F.B., and G.R.R.), University of Rochester Medical Center, Box 665, 601 Elmwood Avenue, Rochester, NY 14642. E-mail address for J.F. Baumhauer: Judy_Baumhauer@Urmc.rochester.edu
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Disclosure: The authors did not receive any outside funding or grants in support of their research for or preparation of this work. Neither they nor a member of their immediate families received payments or other benefits or a commitment or agreement to provide such benefits from a commercial entity. No commercial entity paid or directed, or agreed to pay or direct, any benefits to any research fund, foundation, division, center, clinical practice, or other charitable or nonprofit organization with which the authors, or a member of their immediate families, are affiliated or associated.
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Investigation performed at the Department of Orthopaedics and Rehabilitation, University of Rochester Medical Center, Rochester, New York

The Journal of Bone and Joint Surgery, Inc.
J Bone Joint Surg Am, 2009 Feb 01;91(2):297-304. doi: 10.2106/JBJS.H.00407
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Abstract

Background: Use of c-arm fluoroscopy is common in the operating room, outpatient clinic, and emergency department. Consequently, there is a concern regarding radiation exposure. Mini-c-arm fluoroscopes have gained popularity; however, few studies have quantified exposure during mini-c-arm imaging of a body part larger than a hand or wrist. The purpose of this study was to measure radiation exposure sustained by the patient and surgeon during the use of large and mini-c-arm fluoroscopy of an ankle specimen.

Methods: Standard and mini-c-arm fluoroscopes were used to image a cadaver ankle specimen, which was suspended on an adjustable platform. Dosimeters were mounted at specific positions and angulations to detect direct and scatter radiation. Testing was conducted under various scenarios that altered the proximity of the specimen and the radiation source. We attempted to capture a range of exposure data under conditions ranging from a best to a worst-case scenario, as one may encounter in a procedural setting.

Results: With all configurations tested, measurable exposure during use of the large-c-arm fluoroscope was considerably higher than that during use of the mini-c-arm fluoroscope. Patient and surgeon exposure was notably amplified when the specimen was positioned closer to the x-ray source. The exposure values that we measured during ankle fluoroscopy were consistently higher than the exposure values that have been recorded previously during hand or wrist imaging.

Conclusions: Exposure of the patient and surgeon to radiation depends on the tissue density and the shape of the imaged extremity. Elevated exposure levels can be expected when larger body parts are imaged or when the extremity is positioned closer to the x-ray source. When it is possible to satisfactorily image an extremity with use of the mini c-arm, it should be chosen over its larger counterpart.

Clinical Relevance: Orthopaedists should exercise caution, and consistently follow radiation safety guidelines, when using c-arm fluoroscopes because there is a real risk of radiation exposure.

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    References

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    These activities have been planned and implemented in accordance with the Essential Areas and policies of the Accreditation Council for Continuing Medical Education (ACCME) through the joint sponsorship of the American Academy of Orthopaedic Surgeons and The Journal of Bone and Joint Surgery, Inc. The American Academy of Orthopaedic Surgeons is accredited by the ACCME to provide continuing medical education for physicians.
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    Judith F. Baumhauer, MD
    Posted on March 07, 2009
    Dr. Baumhauer and colleagues respond to Drs. Opreanu and Kepros
    University of Rochester Medical Center

    Drs. Opreanu and Kepros bring up an excellent point regarding the relative radiosensitivity of the various tissues exposed during diagnostic imaging. As we note in our study, when using C-arm fluoroscopy to image a body area in the normal mode, technique factors are adjusted automatically according to the tissue density and cross sectional area. Therefore, during imaging of larger, denser body areas such as the pelvis or spine, technique factors may be increased by a considerable margin, thus subjecting not only the bones and muscles, but also the more radiosensitive underlying visceral organs to elevated levels of radiation. These body areas are routinely imaged using C- arm fluoroscopy during both elective orthopaedic and trauma surgical procedures. In separate publications, we examine radiation exposure to the patient and surgical team during imaging of the cervical spine (1, 2). In conjunction with this current publication, our data would suggest that even more vigilance must be practiced when imaging the musculoskeletal system adjacent to other especially susceptible body areas.

    We feel that it is important to note that one cannot receive too little radiation over the course of one’s lifetime. Regardless of the radiosensitivity of the biological tissues being exposed to ionizing radiation, reaching often cited maximal exposure limits (as set forth by regulatory boards such as the NCRP and ICRP) should not be viewed as optimal or desirable. The readers should be aware that these values have been modified throughout the years, and that international standards are stricter than those imposed in the US. When discussing risks associated with radiation exposure, many authors first look at the maximum allowable exposure limits and then extrapolate backwards to determine how many cases may be done before exceeding these limits. In like fashion, Drs. Opreanu and Kepros frame their sentiments relative to threshold levels (that in our study and many other studies are not reached for the surgeon or surgical team). We feel that this manner of reasoning should be reversed. The question we should ask ourselves should be, “how can I change my practice to minimize radiation exposure to my patients and myself?” rather than “how many procedures can I do before I exceed my yearly exposure limit?”

    We again remind the reader that the concept of ALARA (As Low As Reasonably Achievable) should be followed at all times. While the exposure levels capable of producing deterministic effects are well known, the cumulative effects of consistent radiation exposure remain unknown. As we point out, epidemiological data suggests that exposure to as “little” as 5 -10 Rem over a lifetime increases the risk of developing cancer (3). This figure applies to both physicians and patients. Interestingly, when we used a highly sensitive portable ion chamber to measure background scatter (even 20 ft from the testing zone), it still recorded 200 μrem/hr during mini-c- arm imaging. While this dose is seemingly inconsequential, it highlights the fact that scatter radiation is present even at great distances from the radiation source and is not zero as some believe. Furthermore, although a radiation dosimeter badge may report zero mrem detected, this is often not the case. Many dosimeters begin registering exposure at 10 mrem. Thus, exposure below this level is reported as zero.

    Our study seeks to bring awareness to the fact that the use of fluoroscopy in medicine for indirect visualization is not without risk. As the use of fluoroscopy becomes more and more commonplace in daily practice, we must continue to scrutinize the detrimental effects that its use may pose to our patients and ourselves. Often, physicians and surgeons have no idea how much radiation a patient is exposed to during procedural or diagnostic imaging. Furthermore, many find it difficult to apply exposure levels to an understandable frame of reference that makes such levels relevant and meaningful to them. Rather than using threshold values to determine the number of allowable cases per year, our hope is that physicians and surgeons will begin to alter their practice habits and work backwards from a “worst case scenario” when considering the safety aspects of radiation exposure; ie, careful scrutiny of the necessity of imaging studies, consideration of alternative imaging modalities, limiting the use of live fluoro in the operating room, collimating images, always using protective equipment, consistently practice dose reducing techniques etc.

    References

    1. Giordano BD, Baumhauer JF, Morgan TL, Rechtine GR. Cervical spine imaging using standard C-arm fluoroscopy. Patient and surgeon exposure to ionizing radiation. Spine. 33(18):1970-1976. 2008.

    2. Giordano BD, Baumhauer JF, Morgan TL, Rechtine GR. Cervical spine imaging using mini C-arm fluoroscopy: Patient and surgeon exposure to direct and scatter radiation. Accepted for publication in Journal of Spinal Disorders and Techniques.

    3. Brenner DJ, et al. Cancer risks attributable to low doses of ionizing radiation. Assessing what we really know. Proc. Natl. Acad. Sci. USA. 100:13761-6. 2003.

    Razvan C. Opreanu
    Posted on February 19, 2009
    Is Intra-operative Fluoroscopy Harmful?
    Michigan State University/Department of Surgery

    To the Editor:

    We read with much interest the recent article by Giordano et al. (1). It addresses an important issue arising from the increasing use of x-ray imaging in medicine. Although the authors correctly concluded that protective safety measures should be enforced when using intra-operative fluoroscopy, it might be useful to the reader to have a more complete understanding about the magnitude of these radiation doses.

    The authors recognized that the radiation received during fluoroscopy was very low when compared to the dose of radiation that can cause deterministic (hair loss or burns) or stochastic effects (carcinogenesis or genetic effects). At first look, the dose received by the patient in the worst case scenario seems to be very high, but one must consider that while the amount of radiation is an important parameter in determining the associated risk, the radiosensitivity of the exposed tissues is important as well. For example, muscle and bone are the least radiosensitive tissues in the human body (2).

    For a surgeon operating in the standing position, a dose of 0.38 mGy could reach the gonads, the most radiosensitive organs in the body, and generate a more harmful effect than a dose 90 mGy delivered to the foot or hand of a patient. The resulting radiation doses from this study are approximately 6600 and 5 times less, respectively, than the threshold dose for tissue effects in gonads and bone marrow (2.5 Gy and 0.5 Gy) (2).

    While safety precautions should be in place in the operating room, one must not overestimate the adverse effects associated with the use of fluoroscopy. Assessment by the authors of lifetime attributable risk of cancer incidence or mortality associated with the consistent use of fluoroscopy would have provided a more realistic understanding about the potential associated risks.

    The authors did not receive any outside funding or grants in support of their research for or preparation of this work. Neither they nor a member of their immediate families received payments or other benefits or a commitment or agreement to provide such benefits from a commercial entity. No commercial entity paid or directed, or agreed to pay or direct, any benefits to any research fund, foundation, division, center, clinical practice, or other charitable or nonprofit organization with which the authors, or a member of their immediate families, are affiliated or associated.

    References

    1. Giordano, B.D., et al., Patient and surgeon radiation exposure: comparison of standard and mini-C-arm fluoroscopy. J Bone Joint Surg Am, 2009. 91(2): p. 297-304.

    2. The 2007 Recommendations of the International Commission on Radiological Protection. ICRP publication 103. Ann ICRP, 2007. 37(2-4): p. 1-332.

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