title: A new robotic needle insertion method to minimise attendant prostate motion.
abstract: OBJECTIVE
  The purpose of this study is to investigate the efficacy of a new needle insertion method (tapping instead of pushing) in reducing attendant tissue motion. This can be useful in applications where tissue motion due to needle insertion is problematic such as e.g. MRI-guided prostate brachytherapy and breast biopsies. In this study we will focus on prostate motion due to needle insertion.
  
  
  METHODS
  Prostate motion due to needle insertion was measured in 30 patients, who were transperineally implanted with fiducial gold markers for position verification in prostate intensity modulated radiotherapy. In total 32 needles were manually pushed into the prostate and 29 were tapped with a prototype robotic system. The prostate motion in the cranio-caudal direction was measured on the video record of the ultrasound images. Differences in prostate motion between the two needle insertion methods were analysed making use of SPSS.
  
  
  RESULTS
  The mean prostate motion was 5.6mm (range 0.3-21.6) when the needle was pushed and 0.9 mm (range 0-2.0) when the needle was tapped into the prostate (p<0.001).
  
  
  CONCLUSIONS
  Prostate motion was significantly less when the needle was tapped into the prostate compared to when the needle was pushed. This result is important for the development of a tapping, MRI-guided, prostate implant robotic system.
authors.affiliation: Department of Radiotherapy, University Medical Center Utrecht, Utrecht, The Netherlands. V.Lagerburg@umcutrecht.nl
authors.forename: Vera
authors.initials: V
authors.lastname: Lagerburg
authors.forename: Marinus A
authors.initials: MA
authors.lastname: Moerland
authors.forename: Marco
authors.initials: M
authors.lastname: van Vulpen
authors.forename: Jan J W
authors.initials: JJ
authors.lastname: Lagendijk
mesh_terms: D001706:Biopsy; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D009038:Motion; D009339:Needles; D011467:Prostate / Q000473:pathology*; D011471:Prostatic Neoplasms / Q000473:pathology* / Q000532:radiotherapy*; D011879:Radiotherapy Dosage; D050397:Radiotherapy, Intensity-Modulated / Q000295:instrumentation* / Q000379:methods; D012371:Robotics