title: Initial characterization of the dosimetry and radiology of a device for administering interstitial stereotactic radiosurgery.
abstract: OBJECTIVE
  We report the design and initial characterization of the dosimetry and radiobiology of a novel device for interstitial stereotactic radiosurgery.
  
  
  METHODS
  The device is lightweight, handheld, and battery-powered, and it emits x-ray radiation from the tip of a probe 3 mm in diameter by 10 cm in length.
  
  
  METHODS
  The dosimetry was characterized by two independent methods: thermoluminescent dosimeters and radiochromic film. The radiobiology was characterized by in vivo irradiation of rat liver, dog liver, and dog brain. The animals were killed at varying intervals of time, and histological examinations were performed. Heat transfer from the probe to dog brain was studied in vivo by placing thermocouple sensors around the probe tip before irradiating.
  
  
  RESULTS
  Both dosimetric methods showed a steep dose-distance fall-off relationship (proportional to the reciprocal of the cube of the distance from the probe tip). Rats and dogs that were killed weeks to months after liver irradiation tended to have sharply demarcated lesions. Liver enzyme levels, measured serially in the dogs, did not give evidence of chronic inflammation. Histological examination of the brains of dogs that were killed acutely after irradiation did not show evidence of inflammation, edema, or hemorrhage. The tissue temperature elevation 1 cm from the tip never exceeded 0.5 degree C, thereby excluding hyperthermia as a significant contributor to the formation of lesions.
  
  
  CONCLUSIONS
  Because this device requires relatively few supporting resources, has sharp dosimetric properties, and seems to be safe, it may be useful as a clinical tool for interstitial stereotactic radiosurgery.
authors.affiliation: Department of Radiation Medicine, Masachusetts General Hospital, Boston, USA.
authors.forename: R
authors.initials: R
authors.lastname: Hakim
authors.forename: N T
authors.initials: NT
authors.lastname: Zervas
authors.forename: F
authors.initials: F
authors.lastname: Hakim
authors.forename: W E
authors.initials: WE
authors.lastname: Butler
authors.forename: J
authors.initials: J
authors.lastname: Beatty
authors.forename: J C
authors.initials: JC
authors.lastname: Yanch
authors.forename: P J
authors.initials: PJ
authors.lastname: Biggs
authors.forename: K P
authors.initials: KP
authors.lastname: Gall
authors.forename: A P
authors.initials: AP
authors.lastname: Sliski
mesh_terms: D000818:Animals; D001921:Brain / Q000473:pathology / Q000601:surgery; D004285:Dogs; D004867:Equipment Design; D005373:Film Dosimetry / Q000295:instrumentation*; D006801:Humans; D008099:Liver / Q000473:pathology / Q000601:surgery; D016634:Radiosurgery / Q000295:instrumentation*; D051381:Rats; D013819:Thermoluminescent Dosimetry / Q000295:instrumentation*