The value of image coregistration during stereotactic radiosurgery

T. Koga, K. Maruyama, H. Igaki, M. Tago, N. Saito

Research output: Contribution to journalArticlepeer-review

15 Scopus citations


Background: Coregistration of any neuroimaging studies into treatment planning for stereotactic radiosurgery became easily applicable using the Leksell Gamma Knife 4C, a new model of gamma knife. The authors investigated the advantage of this image processing. Method: Since installation of the Leksell Gamma Knife 4C at the authors' institute, 180 sessions of radiosurgery were performed. Before completion of planning, coregistration of frameless images of other modalities or previous images was considered to refine planning. Treatment parameters were compared for planning before and after refinement by use of coregistered images. Findings: Coregistered computed tomography clarified the anatomical structures indistinct on magnetic resonance imaging. Positron emission tomography visualized lesions disclosing metabolically high activity. Coregistration of prior imaging distinguished progressing lesions from stable ones. Diffusion-tensor tractography was integrated for lesions adjacent to the corticospinal tract or the optic radiation. After refinement of planning in 36 sessions, excess treated volume decreased (p∈=∈0.0062) and Paddick conformity index improved (p∈<∈0.001). Maximal dose to the white matter tracts was decreased (p∈<∈0.001). Conclusion: Image coregistration provided direct information on anatomy, metabolic activity, chronological changes, and adjacent critical structures. This gathered information was sufficiently informative during treatment planning to supplement ambiguous information on stereotactic images, and was useful especially in reducing irradiation to surrounding normal structures.

Original languageEnglish (US)
Pages (from-to)465-471
Number of pages7
JournalActa Neurochirurgica
Issue number5
StatePublished - May 2009
Externally publishedYes


  • Gamma Knife 4C
  • Gamma knife surgery
  • Image coregistration
  • Treatment planning


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