Figure 2.

Image-guided stereotactic delivery of radiation to implanted tumors. (A) Spin-echo MRI of a mouse intracranial tumor using a 9.4-T MR spectrometer to determine the precise anatomic localization of the xenograft. The tumor volume was contoured in pink using the software package Amira. (B) Point of maximal bioluminescent signal for the tumor was determined (red arrow), and the spot was tattooed to aid in the setup of radiation treatment. (C) Anesthetized mouse secured in the home-built novel stereotactic restrainer. The point of maximal bioluminescent signal, identified previously, is covered by a fiducial marker (red arrow) to facilitate identification of the location on CT imaging for treatment planning. (D) Treatment planning CT scans showing the coronal, axial, and sagittal views of the brain. The small red crosses in each image indicate the selected isocenter. In the top right image, the coronal CT of the brain reveals three coplanar fiducial markers used to confirm proper setup for treatment (the scalp fiducial marker and two lateral fiducial markers on the restrainer seen at the bottom corners). (E) Irradiation of exposure film using the 5 x 5-mm collimator confirmed that the SARRP can deliver a collimated beam of radiation with very limited scatter. The irradiated field was centered within ±0.25 mm on its isocenter.