title: Technical Note: Immunohistochemical evaluation of mouse brain irradiation targeting accuracy with 3D-printed immobilization device.
abstract: OBJECTIVE
  Small animal immobilization devices facilitate positioning of animals for reproducible imaging and accurate focal radiation therapy. In this study, the authors demonstrate the use of three-dimensional (3D) printing technology to fabricate a custom-designed mouse head restraint. The authors evaluate the accuracy of this device for the purpose of mouse brain irradiation.
  
  
  METHODS
  A mouse head holder was designed for a microCT couch using cad software and printed in an acrylic based material. Ten mice received half-brain radiation while positioned in the 3D-printed head holder. Animal placement was achieved using on-board image guidance and computerized asymmetric collimators. To evaluate the precision of beam localization for half-brain irradiation, mice were sacrificed approximately 30 min after treatment and brain sections were stained for γ-H2AX, a marker for DNA breaks. The distance and angle of the γ-H2AX radiation beam border to longitudinal fissure were measured on histological samples. Animals were monitored for any possible trauma from the device.
  
  
  RESULTS
  Visualization of the radiation beam on ex vivo brain sections with γ-H2AX immunohistochemical staining showed a sharp radiation field within the tissue. Measurements showed a mean irradiation targeting error of 0.14±0.09 mm (standard deviation). Rotation between the beam axis and mouse head was 1.2°±1.0° (standard deviation). The immobilization device was easily adjusted to accommodate different sizes of mice. No signs of trauma to the mice were observed from the use of tooth block and ear bars.
  
  
  CONCLUSIONS
  The authors designed and built a novel 3D-printed mouse head holder with many desired features for accurate and reproducible radiation targeting. The 3D printing technology was found to be practical and economical for producing a small animal imaging and radiation restraint device and allows for customization for study specific needs.
authors.affiliation: Department of Medical Biophysics, The University of Western Ontario, 1151 Richmond Street, London, Ontario N6A 3K7, Canada.
authors.forename: Niloufar
authors.initials: N
authors.lastname: Zarghami
authors.affiliation: Department of Medical Biophysics, The University of Western Ontario, 1151 Richmond Street, London, Ontario N6A 3K7, Canada.
authors.forename: Michael D
authors.initials: MD
authors.lastname: Jensen
authors.affiliation: Department of Biochemistry, The University of Western Ontario, 1151 Richmond Street, London, Ontario N6A 3K7, Canada and London Regional Cancer Program, London Health Sciences Centre, 800 Commissioners Road East, London, Ontario N6A 5W9, Canada.
authors.forename: Srikanth
authors.initials: S
authors.lastname: Talluri
authors.affiliation: Imaging Research Laboratories, Robarts Research Institute, 100 Perth Drive, London, Ontario N6A 5K8, Canada and Department of Medical Biophysics, The University of Western Ontario, 1151 Richmond Street, London, Ontario N6A 3K7, Canada.
authors.forename: Paula J
authors.initials: PJ
authors.lastname: Foster
authors.affiliation: Department of Medical Biophysics, The University of Western Ontario, 1151 Richmond Street, London, Ontario N6A 3K7, Canada; Department of Oncology, The University of Western Ontario, 1151 Richmond Street, London, Ontario N6A 3K7, Canada; and London Regional Cancer Program, London Health Sciences Centre, 800 Commissioners Road East, London, Ontario N6A 5W9, Canada.
authors.forename: Ann F
authors.initials: AF
authors.lastname: Chambers
authors.affiliation: Department of Biochemistry, The University of Western Ontario, 1151 Richmond Street, London, Ontario N6A 3K7, Canada and London Regional Cancer Program, London Health Sciences Centre, 800 Commissioners Road East, London, Ontario N6A 5W9, Canada.
authors.forename: Frederick A
authors.initials: FA
authors.lastname: Dick
authors.affiliation: Department of Physics and Astronomy, The University of Western Ontario, 1151 Richmond Street, London, Ontario N6A 3K7, Canada; Department of Medical Biophysics, The University of Western Ontario, 1151 Richmond Street, London, Ontario N6A 3K7, Canada; Department of Oncology, The University of Western Ontario, 1151 Richmond Street, London, Ontario N6A 3K7, Canada; and London Regional Cancer Program, London Health Sciences Centre, 800 Commissioners Road East, London, Ontario N6A 5W9, Canada.
authors.forename: Eugene
authors.initials: E
authors.lastname: Wong
mesh_terms: D000818:Animals; D001921:Brain / Q000473:pathology* / Q000528:radiation effects*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D007103:Immobilization / Q000295:instrumentation* / Q000662:veterinary*; D051379:Mice; D008810:Mice, Inbred C57BL; D066330:Printing, Three-Dimensional / Q000295:instrumentation; D011878:Radiotherapy / Q000295:instrumentation* / Q000662:veterinary*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity