title: Cadaveric verification of the Eclipse AAA algorithm for spine SBRT treatments with titanium hardware.
abstract: OBJECTIVE
  To assess the accuracy of the Eclipse Analytical Anisotropic Algorithm when calculating dose for spine stereotactic body radiation therapy treatments involving surgically implanted titanium hardware.
  
  
  METHODS
  A human spine was removed from a cadaver, cut sagittally along the midline, and then separated into thoracic and lumbar sections. The thoracic section was implanted with titanium stabilization hardware; the lumbar section was not implanted. Spine sections were secured in a water phantom and simulated for treatment planning using both standard and extended computed tomography (CT) scales. Target volumes were created on both spine sections. Dose calculations were performed using (1) the standard CT scale with relative electron density (RED) override of image artifacts and hardware, (2) the extended CT scale with RED override of image artifacts only, and (3) the standard CT scale with no RED overrides for hardware or artifacts. Plans were delivered with volumetric modulated arc therapy using a 6-MV beam with and without a flattening filter. A total of 3 measurements for each plan were made with Gafchromic film placed between the spine sections and compared with Eclipse dose calculations using gamma analysis with a 2%/2 mm passing criteria. A single measurement in a homogeneous phantom was made for each plan before actual delivery.
  
  
  RESULTS
  Gamma passing rates for measurements in the homogeneous phantom were 99.6% or greater. Passing rates for measurements made in the lumbar spine section without hardware were 99.3% or greater; measurements made in the thoracic spine containing titanium were 98.6 to 99.5%.
  
  
  CONCLUSIONS
  Eclipse Analytical Anisotropic Algorithm can adequately model the effects of titanium implants for spine stereotactic body radiation therapy treatments using volumetric modulated arc therapy. Calculations with standard or extended CT scales give similarly accurate results.
authors.affiliation: Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota. Electronic address: grams.michael@mayo.edu.
authors.forename: Michael P
authors.initials: MP
authors.lastname: Grams
authors.affiliation: Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota.
authors.forename: Luis E
authors.initials: LE
authors.lastname: Fong de Los Santos
authors.affiliation: Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota.
authors.forename: John A
authors.initials: JA
authors.lastname: Antolak
authors.affiliation: Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota.
authors.forename: Debra H
authors.initials: DH
authors.lastname: Brinkmann
authors.affiliation: Department of Neurologic Surgery, Mayo Clinic, Rochester, Minnesota.
authors.forename: Michelle J
authors.initials: MJ
authors.lastname: Clarke
authors.affiliation: Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota.
authors.forename: Sean S
authors.initials: SS
authors.lastname: Park
authors.affiliation: Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota.
authors.forename: Kenneth R
authors.initials: KR
authors.lastname: Olivier
authors.affiliation: Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota.
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Whitaker
mesh_terms: D000465:Algorithms; D002102:Cadaver; D006801:Humans; D008297:Male; D008875:Middle Aged; D019047:Phantoms, Imaging; D011874:Radiometry; D016634:Radiosurgery / Q000379:methods*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D013131:Spine / Q000033:anatomy & histology / Q000528:radiation effects* / Q000601:surgery*; D014025:Titanium
chemical_list: D014025:Titanium