title: Plug pattern optimization for gamma knife radiosurgery treatment planning.
abstract: OBJECTIVE
  To develop a novel dose optimization algorithm for improving the sparing of critical structures during gamma knife radiosurgery by shaping the plug pattern of each individual shot.
  
  
  METHODS
  We first use a geometric information (medial axis) aided guided evolutionary simulated annealing (GESA) optimization algorithm to determine the number of shots and isocenter location, size, and weight of each shot. Then we create a plug quality score system that checks the dose contribution to the volume of interest by each plug in the treatment plan. A positive score implies that the corresponding source could be open to improve tumor coverage, whereas a negative score means the source could be blocked for the purpose of sparing normal and critical structures. The plug pattern is then optimized via the GESA algorithm that is integrated with this score system. Weight and position of each shot are also tuned in this procedure.
  
  
  RESULTS
  An acoustic tumor case is used to evaluate our algorithm. Compared to the treatment plan generated without plug patterns, adding an optimized plug pattern into the treatment planning process boosts tumor coverage index from 95.1% to 97.2%, reduces RTOG conformity index from 1.279 to 1.167, lowers Paddick's index from 1.34 to 1.20, and trims the critical structure receiving more than 30% maximum dose from 16 mm(3) to 6 mm(3).
  
  
  CONCLUSIONS
  Automated GESA-based plug pattern optimization of gamma knife radiosurgery frees the treatment planning team from the manual forward planning procedure and provides an optimal treatment plan.
authors.affiliation: Department of Radiation Oncology, Columbia University, New York, NY, USA.
authors.forename: Pengpeng
authors.initials: P
authors.lastname: Zhang
authors.forename: Jackie
authors.initials: J
authors.lastname: Wu
authors.forename: David
authors.initials: D
authors.lastname: Dean
authors.forename: Lei
authors.initials: L
authors.lastname: Xing
authors.forename: Jinyue
authors.initials: J
authors.lastname: Xue
authors.forename: Robert
authors.initials: R
authors.lastname: Maciunas
authors.forename: Claudio
authors.initials: C
authors.lastname: Sibata
mesh_terms: D000465:Algorithms; D001932:Brain Neoplasms / Q000601:surgery; D006801:Humans; D009464:Neuroma, Acoustic / Q000601:surgery; D016634:Radiosurgery / Q000379:methods* / Q000592:standards; D011879:Radiotherapy Dosage