title: Planning evaluation of C-arm cone beam CT angiography for target delineation in stereotactic radiation surgery of brain arteriovenous malformations.
abstract: OBJECTIVE
  Stereotactic radiation surgery (SRS) is one of the therapeutic modalities currently available to treat cerebral arteriovenous malformations (AVM). Conventionally, magnetic resonance imaging (MRI) and MR angiography (MRA) and digital subtraction angiography (DSA) are used in combination to identify the target volume for SRS treatment. The purpose of this study was to evaluate the use of C-arm cone beam computed tomography (CBCT) in the treatment planning of SRS for cerebral AVMs.
  
  
  METHODS
  Sixteen consecutive patients treated for brain AVMs at our institution were included in this retrospective study. Prior to treatment, all patients underwent MRA, DSA, and C-arm CBCT. All images were coregistered using the GammaPlan planning system. AVM regions were delineated independently by 2 physicians using either C-arm CBCT or MRA, resulting in 2 volumes: a CBCT volume (VCBCT) and an MRA volume (VMRA). SRS plans were generated based on the delineated regions.
  
  
  RESULTS
  The average volume of treatment targets delineated using C-arm CBCT and MRA were similar, 6.40 cm(3) and 6.98 cm(3), respectively (P=.82). However, significant regions of nonoverlap existed. On average, the overlap of the MRA with the C-arm CBCT was only 52.8% of the total volume. In most cases, radiation plans based on VMRA did not provide adequate dose to the region identified on C-arm CBCT; the mean minimum dose to VCBCT was 29.5%, whereas the intended goal was 45% (P<.001). The mean volume of normal brain receiving 12 Gy or more in C-arm CBCT-based plans was not greater than in the MRA-based plans.
  
  
  CONCLUSIONS
  Use of C-arm CBCT images significantly alters the delineated regions of AVMs for SRS planning, compared to that of MRA/MRI images. CT-based planning can be accomplished without increasing the dose to normal brain and may represent a more accurate definition of the nidus, increasing the chances for successful obliteration.
authors.affiliation: Radiation Oncology Department, Abington Memorial Hospital, Philadelphia, Pennsylvania; Department of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland.
authors.forename: Jun
authors.initials: J
authors.lastname: Kang
authors.affiliation: Department of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, Maryland.
authors.forename: Judy
authors.initials: J
authors.lastname: Huang
authors.affiliation: Division of Interventional Neuroradiology, Johns Hopkins University School of Medicine, Baltimore, Maryland.
authors.forename: Philippe
authors.initials: P
authors.lastname: Gailloud
authors.affiliation: Department of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, Maryland.
authors.forename: Daniele
authors.initials: D
authors.lastname: Rigamonti
authors.affiliation: Department of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, Maryland.
authors.forename: Michael
authors.initials: M
authors.lastname: Lim
authors.affiliation: Department of Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, Maryland.
authors.forename: Vincent
authors.initials: V
authors.lastname: Bernard
authors.affiliation: Siemens Corporate Research, Baltimore, Maryland.
authors.forename: Tina
authors.initials: T
authors.lastname: Ehtiati
authors.affiliation: Department of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland; Radiation Oncology, University of Washington, Seattle, Washington. Electronic address: eford@uw.edu.
authors.forename: Eric C
authors.initials: EC
authors.lastname: Ford
mesh_terms: D015901:Angiography, Digital Subtraction / Q000379:methods*; D002533:Cerebral Angiography / Q000379:methods*; D054893:Cone-Beam Computed Tomography / Q000379:methods*; D006801:Humans; D002538:Intracranial Arteriovenous Malformations / Q000175:diagnosis / Q000000981:diagnostic imaging* / Q000601:surgery*; D018810:Magnetic Resonance Angiography; D016634:Radiosurgery; D011879:Radiotherapy Dosage