Norah A. Foster, MD, and Duke Spine Center Making Strides in the study of Intraoperative Radiation Exposure

Meet Steve, also known as an adult male anthropomorphic Model 701-D phantom (CIRS, Inc, Norfolk, VA, USA). With Steve’s help, the Duke Spine Center has been working towards better understanding intraoperative radiation exposure to patients and operating room staff at Duke University Medical Center.



As the field of spine surgery has advanced in recent years, so too have our intraoperative imaging modalities. From direct visualization, to serial radiography, to C-arm fluoroscopy, to 3-dimensional imaging, our ability to localize levels and properly place implants intraoperatively has evolved at an incredibly fast pace. And while surgeons may have a plethora of intraoperative imaging modalities available, they each come with their respective advantages and disadvantages; including a risk of radiation exposure to the patient and the operating room (OR) personnel.

With increased utilization of intraoperative ionizing imaging modalities, radiation exposure within healthcare is likewise increasing. Little is known about chronic exposure to low doses of ionizing radiation and the long-term health effects. Current guidelines set out by the National Council on Radiation Protection and Measurement (NCRP) and the Occupational Safety & Health Administration (OSHA) limit the maximum annual radiation cumulative whole body dose to 5 rem yearly for occupational workers. For members of the public, the NCRP recommends an annual effective dose limit of 0.1 rem. However, there are no corresponding radiation exposure limitations for patients within the healthcare system. The principles of exposure are based on acceptable levels of calculated risk and the general consensus is that a dose “as low as reasonably achievable” (ALARA) should be the goal regardless of the recommended maximum.  

Not only can the choice of imaging modality significantly impact the potential cumulative radiation dose for the patient and the OR staff, but a patient’s body habitus can also play a role. Greater radiation exposure in obese patients has been documented in several studies involving spinal surgery.

Assessment of the radiation risk is an integral part of the decision-making behind the use of any intraoperative spinal imaging modality. Duke University Medical Center has stayed ahead of the curve with respect to intraoperative imaging systems and this institution has the distinctive availability of several intraoperative imaging systems from which to select. In coordination with the Duke Radiation Dosimetry Lab, the Duke Spine Center faculty have studied five different imaging systems to include: OEC 9900 Elite Mobile C-Arm (GE, Salt Lake City, UT, USA), Arcadis® Orbic 3D (Siemens, Erlangen, Germany), VISIUS iCT (iMRIS, Minnetonka, MN, USA), O-arm® (Medtronic, Minneapolis, MN, USA) and Airo (Mobius, Shirley, MA, USA).

Preliminary results have demonstrated that increased patient body mass index or BMI does portend an increased effective dose of radiation to the patient with use of all the imaging systems. Also, imaging systems which utilize CT technology are associated with a higher effective dose of radiation to the patient as well as the OR personnel. This work is helping to provide surgeons with comparative data with respect to radiation exposure for different imaging systems in order to help them make educated decisions regarding the risks and benefits of utilization. Continued work with respect to radiation safety and minimizing radiation exposure is planned in order to ensure optimal patient care at Duke University Medical Center.

Norah Foster

Article written by Norah A. Foster, MD
March 3, 2016

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