title: Estimating the effective radiation dose imparted to patients by intraoperative cone-beam computed tomography in thoracolumbar spinal surgery.
abstract: METHODS
  Observational.
  
  
  OBJECTIVE
  To estimate the radiation dose imparted to patients during typical thoracolumbar spinal surgical scenarios.
  
  
  BACKGROUND
  Minimally invasive techniques continue to become more common in spine surgery. Computer-assisted navigation systems coupled with intraoperative cone-beam computed tomography (CT) represent one such method used to aid in instrumented spinal procedures. Some studies indicate that cone-beam CT technology delivers a relatively low dose of radiation to patients compared with other x-ray-based imaging modalities. The goal of this study was to estimate the radiation exposure to the patient imparted during typical posterior thoracolumbar instrumented spinal procedures, using intraoperative cone-beam CT and to place these values in the context of standard CT doses.
  
  
  METHODS
  Cone-beam CT scans were obtained using Medtronic O-arm (Medtronic, Minneapolis, MN). Thermoluminescence dosimeters were placed in a linear array on a foam-plastic thoracolumbar spine model centered above the radiation source for O-arm presets of lumbar scans for small or large patients. In-air dosimeter measurements were converted to skin surface measurements, using published conversion factors. Dose-length product was calculated from these values. Effective dose was estimated using published effective dose to dose-length product conversion factors.
  
  
  RESULTS
  Calculated dosages for many full-length procedures using the small-patient setting fell within the range of published effective doses of abdominal CT scans (1-31 mSv). Calculated dosages for many full-length procedures using the large-patient setting fell within the range of published effective doses of abdominal CT scans when the number of scans did not exceed 3.
  
  
  CONCLUSIONS
  We have demonstrated that single cone-beam CT scans and most full-length posterior instrumented spinal procedures using O-arm in standard mode would likely impart a radiation dose within the range of those imparted by a single standard CT scan of the abdomen. Radiation dose increases with patient size, and the radiation dose received by larger patients as a result of more than 3 O-arm scans in standard mode may exceed the dose received during standard CT of the abdomen. Understanding radiation imparted to patients by cone-beam CT is important for assessing risks and benefits of this technology, especially when spinal surgical procedures require multiple intraoperative scans.
authors.affiliation: Department of Orthopedic Surgery, University of Massachusetts Medical School, Worcester, MA 01655, USA. jeffrey.lange2@umassmemorial.org
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Lange
authors.forename: Andrew
authors.initials: A
authors.lastname: Karellas
authors.forename: John
authors.initials: J
authors.lastname: Street
authors.forename: Jason C
authors.initials: JC
authors.lastname: Eck
authors.forename: Anthony
authors.initials: A
authors.lastname: Lapinsky
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Connolly
authors.forename: Christian P
authors.initials: CP
authors.lastname: Dipaola
mesh_terms: D049628:Body Size; D054893:Cone-Beam Computed Tomography / Q000009:adverse effects / Q000295:instrumentation; D004867:Equipment Design; D006801:Humans; D007430:Intraoperative Care; D008159:Lumbar Vertebrae / Q000000981:diagnostic imaging* / Q000601:surgery*; D008953:Models, Anatomic; D019637:Orthopedic Procedures; D011237:Predictive Value of Tests; D011829:Radiation Dosage; D018570:Risk Assessment; D012307:Risk Factors; D012542:Scattering, Radiation; D013819:Thermoluminescent Dosimetry / Q000295:instrumentation; D013904:Thoracic Vertebrae / Q000000981:diagnostic imaging* / Q000601:surgery*; D015898:Tomography Scanners, X-Ray Computed