title: Frameless image guidance improves accuracy in three-dimensional interstitial brachytherapy needle placement.
abstract: OBJECTIVE
  The aim of this work was to adapt a computer-assisted real-time three-dimensional (3D) navigation system for interstitial brachytherapy procedures.
  
  
  METHODS
  The 3-D navigation system Surgical Planning and Orientation Computer System (SPOCS; Aesculap, Tuttlingen, Germany) was adapted for use in interstitial brachytherapy. A special needle holder with mounted infrared-emitting diodes (IRED) for 3D navigation-based needle implantation was developed. Measurements were made on a series of different phantoms to study the feasibility and the overall accuracy and precision of the navigation system with regard to single-needle application and volume implants (multiple-needle implantations). In all, 250 single implants and 20 volume implants were performed. Accuracy was measured as the target registration error (TRE) between the preoperatively defined and the achieved target position.
  
  
  RESULTS
  Analyses of the 250 different targets showed a mean TRE for single-needle applications of 1.1 mm (SD +/- 0.4 mm), 0.9 mm (SD +/- 0.3 mm), and 0.7 mm (SD +/- 0.3 mm) in the x, y, and z direction, respectively. The maximal deviation was 2.3 mm. The corresponding TRE in the x, y, and z direction for volume implants was 1.6 mm (SD +/- 0.4 mm), 1.9 mm (SD +/- 0.6 mm), and 1.0 mm (SD +/- 0.4 mm), respectively. The maximum deviation was 2.9 mm.
  
  
  CONCLUSIONS
  The adaptation of a commercially available surgical planning and navigation system to interstitial brachytherapy is feasible. It enables virtual planning and improved accuracy in 3D interstitial needle implantation.
authors.affiliation: Department of Clinical Radiology, University of Heidelberg, Heidelberg, Germany. robert_krempien@med.uni-heidelberg.de
authors.forename: Robert
authors.initials: R
authors.lastname: Krempien
authors.forename: Stefan
authors.initials: S
authors.lastname: Hassfeld
authors.forename: Josef
authors.initials: J
authors.lastname: Kozak
authors.forename: Hans-Peter
authors.initials: HP
authors.lastname: Tuemmler
authors.forename: Sascha
authors.initials: S
authors.lastname: Däuber
authors.forename: Martina
authors.initials: M
authors.lastname: Treiber
authors.forename: Juergen
authors.initials: J
authors.lastname: Debus
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Harms
mesh_terms: D001918:Brachytherapy / Q000295:instrumentation / Q000379:methods*; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D009339:Needles; D011880:Radiotherapy Planning, Computer-Assisted; D011881:Radiotherapy, Computer-Assisted / Q000379:methods*; D013238:Stereotaxic Techniques