In vivo biological effects of stereotactic radiosurgery: a primate model.
Single-fraction, closed skull, small-volume irradiation (radiosurgery) of intact intracranial structures requires accurate knowledge of radiation tolerance. We have developed a baboon model to assess the in vivo destructive radiobiological effects of stereotactic radiosurgery. Three baboons received a single-fraction, 150-Gy lesion of the caudate nucleus, the thalamus, or the pons using the 8-mm diameter collimator of the gamma unit. Serial standard neurodiagnostic tests (neurological examination, computed tomographic scan, magnetic resonance imaging, stable xenon-enhanced computed tomographic scan of cerebral blood flow, somatosensory and brain stem evoked potentials, and myelin basic protein levels of cerebrospinal fluid) were compared with preoperative studies. Magnetic resonance imaging revealed the development of a lesion at the target site between 45 and 60 days after irradiation. Deterioration of the brain stem evoked potentials preceded imaging changes when the lesion encroached on auditory pathways. Myelin basic protein levels increased subsequent to imaging changes. Postmortem neuropathological examination confirmed a well-demarcated radionecrosis of the target volume. The baboon model appears to be an excellent method to study the in vivo biological effects of radiosurgery.
Department of Neurological Surgery, Presbyterian-University Hospital, University of Pittsburgh School of Medicine, Pennsylvania.
L D
LD
Lunsford
E M
EM
Altschuler
J C
JC
Flickinger
A
A
Wu
A J
AJ
Martinez
D000818:Animals; D002421:Caudate Nucleus / Q000473:pathology / Q000528:radiation effects; D003037:Cobalt Radioisotopes; D016371:Cranial Irradiation / Q000009:adverse effects; D005071:Evoked Potentials; D006429:Hemiplegia / Q000209:etiology; D008279:Magnetic Resonance Imaging; D008297:Male; D004676:Myelin Basic Protein / Q000134:cerebrospinal fluid; D009336:Necrosis; D010215:Papio; D011149:Pons / Q000473:pathology / Q000528:radiation effects; D011833:Radiation Injuries, Experimental / Q000134:cerebrospinal fluid / Q000209:etiology* / Q000473:pathology; D011867:Radioisotope Teletherapy / Q000009:adverse effects; D013238:Stereotaxic Techniques; D013788:Thalamus / Q000473:pathology / Q000528:radiation effects; D014057:Tomography, X-Ray Computed
D003037:Cobalt Radioisotopes; D004676:Myelin Basic Protein