Gamma Knife Perfexion As An Assembly-line Rodent Irradiator

Robert Drzymala1, H. Omar Wooten1, Juan Tellez1, Joel R. Garbow1, Keith M. Rich1, Joseph R. Simpson.1

1Washington University School of Medicine, Saint Louis, USA

Keywords: animal model, stereotactic frame, technique, robotics, gamma knife

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Abstract

      
     Performance of automated irradiation of multiple normal and/or tumor bearing rodent brains with Leksell Gamma Knife Perfexion.
      The LGKP rodent holder assembly was designed to irradiate up to 5 mice in one session.
      The assembly includes a covered plastic platform attached to the Leksell stereotactic ring and mounts to the LGKP couch via the ring adapter. Anesthesia gas can be introduced directly through hose barbs mounted in the removable cover. Immobilized by ear bars and an incisor bar, each rodent lies in the trough of a modular animal platform compartment. Rodents were oriented perpendicular to the couch Z-axis. Animals were monitored during irradiation using a webcam. Two rodent holders were made and CT-scanned with the Leksell localizer frame attached to obtain stereotactic coordinates relative to rodent positions. LGP was used to define a Target and dose at each animal position. Shots were placed anatomically with the appropriate sectors blocked to minimize irradiation of other animals.
     Multiple mice can be rapidly (30s) attached/detached from the Leksell ring. One assembly was loaded with animals, while the other was irradiated. Stereotactic CT-scans show that each assembly can be reproducibly positioned within 0.3mm and the two align within 0.7mm. Dosimetry at each animal position varied by a few percent, easily adjusted using different Target prescriptions in the LGP plan. Mice given 150Gy with 4mm collimation survived to demonstrate acute tissue damage.
     This is an animal experiment of one gamma knife model.
     The rodent holder assembly is described.
     It. allows efficient irradiation of multiple animals using a variety of doses and fractionation schemes.


Acknowledgements

Project Roles:

R. Drzymala (), H. Wooten (), J. Tellez (), J. Garbow (), K. Rich (), J. Simpson. ()