title: Frameless stereotactic radiosurgery of a solitary liver metastasis using active breathing control and stereotactic ultrasound.
abstract: OBJECTIVE
  Radiosurgery of liver metastases is effective but a technical challenge due to respiration-induced movement. The authors report on the initial experience of the combination of active breathing control (ABC) with stereotactic ultrasound (B-mode acquisition and targeting [BAT]) for frameless radiosurgery.
  
  
  METHODS
  A patient with a solitary, inoperable liver metastasis from cholangiocellular carcinoma is presented (Figure 4). ABC (Figure 3) was used for tumor/liver immobilization. Tumor/liver position was controlled and corrected using ultrasound (BAT; Figure 1). The tumor was irradiated with a single dose of 24 Gy.
  
  
  RESULTS
  Using ABC, the motion of the tumor was significantly reduced and the overall positioning error was < 5 mm (Figure 2). BAT allowed a rapid localization of the lesion during breath hold which could be performed without difficulties for 20 s. Overall treatment time was acceptable (30 min).
  
  
  CONCLUSIONS
  Frameless stereotactic radiotherapy with the combination of ABC and BAT allows the delivery of high single doses to targets accessible to ultrasound with high precision comparable to a frame-based approach.
authors.affiliation: Department of Radiation Oncology, Mannheim University Hospital, University of Heidelberg, Mannheim Medical Center, Theodor-Kutzer-Ufer 1-3, 68167 Mannheim, Germany. judit.boda-heggemann@radonk.ma.uni-heidelberg.de
authors.forename: Judit
authors.initials: J
authors.lastname: Boda-Heggemann
authors.forename: Cornelia
authors.initials: C
authors.lastname: Walter
authors.forename: Sabine
authors.initials: S
authors.lastname: Mai
authors.forename: Barbara
authors.initials: B
authors.lastname: Dobler
authors.forename: Dietmar
authors.initials: D
authors.lastname: Dinter
authors.forename: Frederik
authors.initials: F
authors.lastname: Wenz
authors.forename: Frank
authors.initials: F
authors.lastname: Lohr
mesh_terms: D000368:Aged; D005500:Follow-Up Studies; D006801:Humans; D008113:Liver Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy* / Q000556:secondary; D008297:Male; D009038:Motion; D011856:Radiographic Image Enhancement; D016634:Radiosurgery / Q000379:methods; D011879:Radiotherapy Dosage; D012119:Respiration; D013238:Stereotaxic Techniques; D013997:Time Factors; D016896:Treatment Outcome; D014463:Ultrasonography