title: Novel technique for high-precision stereotactic irradiation of mouse brains.
abstract: OBJECTIVE
  Small animal irradiation systems were developed for preclinical evaluation of tumor therapy closely resembling the clinical situation. Mostly only clinical LINACs are available, so protocols for small animal partial body irradiation using a conventional clinical system are essential. This study defines a protocol for conformal brain tumor irradiations in mice.
  
  
  METHODS
  CT and MRI images were used to demarcate the target volume and organs at risk. Three 6 MV photon beams were planned for a total dose of 10 fractions of 1.8 Gy. The mouse position in a dedicated applicator was verified by an X‑ray patient positioning system before each irradiation. Dosimetric verifications (using ionization chambers and films) were performed. Irradiation-induced DNA damage was analyzed to verify the treatment effects on the cellular level.
  
  
  RESULTS
  The defined treatment protocol and the applied fractionation scheme were feasible. The in-house developed applicator was suitable for individual positioning at submillimeter accuracy of anesthetized mice during irradiation, altogether performed in less than 10 min. All mice tolerated the treatment well. Measured dose values perfectly matched the nominal values from treatment planning. Cellular response was restricted to the target volume.
  
  
  CONCLUSIONS
  Clinical LINAC-based irradiations of mice offer the potential to treat orthotopic tumors conformably. Especially with respect to lateral penumbra, dedicated small animal irradiation systems exceed the clinical LINAC solution.
authors.affiliation: Department of Radiation Oncology, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Universitätsstraße 27, 91054, Erlangen, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Hartmann
authors.affiliation: Department of Radiation Oncology, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Universitätsstraße 27, 91054, Erlangen, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Wölfelschneider
authors.affiliation: Institute of Neuropathology, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany.
authors.forename: C
authors.initials: C
authors.lastname: Stache
authors.affiliation: Institute of Neuropathology, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany.
authors.forename: R
authors.initials: R
authors.lastname: Buslei
authors.affiliation: Department of Radiation Oncology, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Universitätsstraße 27, 91054, Erlangen, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Derer
authors.affiliation: Institute of Radiology, Preclinical Imaging Platform Erlangen (PIPE), Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Schwarz
authors.affiliation: Institute of Radiology, Preclinical Imaging Platform Erlangen (PIPE), Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Bäuerle
authors.affiliation: Department of Radiation Oncology, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Universitätsstraße 27, 91054, Erlangen, Germany.
authors.forename: R
authors.initials: R
authors.lastname: Fietkau
authors.affiliation: Department of Radiation Oncology, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Universitätsstraße 27, 91054, Erlangen, Germany.
authors.forename: U S
authors.initials: US
authors.lastname: Gaipl
authors.affiliation: Department of Radiation Oncology, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Universitätsstraße 27, 91054, Erlangen, Germany. christoph.bert@uk-erlangen.de.
authors.forename: C
authors.initials: C
authors.lastname: Bert
authors.affiliation: Institute of Neuropathology, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Hölsken
authors.affiliation: Department of Radiation Oncology, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Universitätsstraße 27, 91054, Erlangen, Germany.
authors.forename: B
authors.initials: B
authors.lastname: Frey
mesh_terms: D000818:Animals; D001932:Brain Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy* / Q000662:veterinary*; D045744:Cell Line, Tumor; D051379:Mice; D056888:Patient Positioning / Q000662:veterinary*; D016634:Radiosurgery / Q000662:veterinary*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000662:veterinary*; D061089:Radiotherapy, Image-Guided / Q000662:veterinary*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D016896:Treatment Outcome
keywords: Craniopharyngioma; Mouse irradiation; Orthotopic; Small field dosimetry; Xenograft