title: Relationships between head fixation pins for radiosurgery and the skull bone--usefulness of a torque wrench.
abstract: BACKGROUND
  In stereotactic radiosurgery (SRS), fixation devices are secured to the patient's head with pins. However, there have been no standards for the use of such pins, which must be inserted with appropriate torque based on the surgeon's clinical judgment. Therefore, the pins may sometimes be tightened excessively and penetrate too deeply into the patient's skull.
  
  
  OBJECTIVE
  To improve safety in SRS, a torque wrench was used for pin insertion. The usefulness of the torque wrench was then evaluated by examining the relationships between the pins and skull bone and identifying differences according to the wrench used and the patient's bone thickness.
  
  
  METHODS
  CT images of patients who had previously undergone SRS were used to assess the relationships between the pins and skull bone. Differences according to the wrench used and pin insertion site were investigated.
  
  
  RESULTS
  Compared with a standard wrench, use of the torque wrench decreased the insertion depth of pins in the skull bone. In terms of site, pins in the forehead were inserted more deeply. No differences related to the frontal sinus were observed.
  
  
  CONCLUSIONS
  The use of a torque wrench improved safety during pin insertion for SRS procedures.
authors.affiliation: Department of Radiology, Mie Prefectural General Medical Center, Oaza-Hinaga, Yokkaichi, Japan.
authors.forename: Shun
authors.initials: S
authors.lastname: Toyota
authors.forename: Hidetoshi
authors.initials: H
authors.lastname: Seta
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Kubo
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Muramatsu
authors.forename: Kan
authors.initials: K
authors.lastname: Takeda
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001858:Bone Nails; D002648:Child; D005260:Female; D005592:Fracture Fixation / Q000295:instrumentation* / Q000379:methods; D006801:Humans; D008297:Male; D008875:Middle Aged; D016634:Radiosurgery / Q000295:instrumentation* / Q000379:methods; D012886:Skull / Q000601:surgery*; D019415:Torque