title: Megavoltage CT-assisted stereotactic radiosurgery for thoracic tumors: original research in the treatment of thoracic neoplasms.
abstract: OBJECTIVE
  The aim of the study was to evaluate the efficacy of stereotactic radiosurgery (SRS) for thoracic tumors with megavoltage computed tomography (MVCT) from the point of view of symptom palliation as well as local control.
  
  
  METHODS
  MVCT-assisted positioning verification and real-time monitoring for a multileaf collimator (MLC) were used to enhance the accuracy of the thoracic SRS. Twenty-two thoracic tumors in 15 patients underwent the present treatment. All but 1 tumor were metastases from various primary malignancies. Eleven patients were symptomatic. The treatment site was the chest wall/pleura in 10 tumors, and the lung in 12 tumors. The median volume of the clinical target was 4.5 cc and the median peripheral dose was 20 Gy, for the lung tumors. For the chest wall/pleura tumors, the median volume of the clinical target was 40 cc and the median peripheral dose was 20 Gy. Conventional fractionated conformal radiation therapy (CRT) followed SRS in 10 tumors.
  
  
  RESULTS
  Of 21 tumors eligible for evaluation, there were 13 with complete responses, 6 with partial responses, and 2 without response. Duration of local control ranged from 0.6 to 82 months with a median of 8 months, with only one local recurrence seen. Immediate palliation was obtained in most symptomatic patients. Interstitial changes in the lung were limited. Autopsy performed for a patient revealed remarkable histologic effects with minimal injuries to the lung.
  
  
  CONCLUSIONS
  The geometric accuracy of MVCT-assisted SRS appeared to enhance the clinical efficacy and safety of treatment to thoracic malignancies.
authors.affiliation: Department of Radiology, University of Tokyo, Tokyo, Japan. d18043@h.u-tokyo.ac.jp
authors.forename: K
authors.initials: K
authors.lastname: Nakagawa
authors.forename: Y
authors.initials: Y
authors.lastname: Aoki
authors.forename: M
authors.initials: M
authors.lastname: Tago
authors.forename: A
authors.initials: A
authors.lastname: Terahara
authors.forename: K
authors.initials: K
authors.lastname: Ohtomo
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D004938:Esophageal Neoplasms / Q000000981:diagnostic imaging / Q000601:surgery; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008175:Lung Neoplasms / Q000000981:diagnostic imaging / Q000556:secondary / Q000601:surgery; D008297:Male; D008875:Middle Aged; D009101:Multiple Myeloma / Q000000981:diagnostic imaging / Q000601:surgery; D010166:Palliative Care; D010997:Pleural Neoplasms / Q000000981:diagnostic imaging / Q000601:surgery; D016634:Radiosurgery / Q000379:methods*; D020266:Radiotherapy, Conformal / Q000379:methods*; D012106:Research; D013899:Thoracic Neoplasms / Q000000981:diagnostic imaging / Q000556:secondary / Q000601:surgery*; D013945:Thymoma / Q000000981:diagnostic imaging / Q000601:surgery; D013953:Thymus Neoplasms / Q000000981:diagnostic imaging / Q000601:surgery; D014057:Tomography, X-Ray Computed / Q000379:methods*