title: IPIP: A new approach to inverse planning for HDR brachytherapy by directly optimizing dosimetric indices.
abstract: OBJECTIVE
  Many planning methods for high dose rate (HDR) brachytherapy require an iterative approach. A set of computational parameters are hypothesized that will give a dose plan that meets dosimetric criteria. A dose plan is computed using these parameters, and if any dosimetric criteria are not met, the process is iterated until a suitable dose plan is found. In this way, the dose distribution is controlled by abstract parameters. The purpose of this study is to develop a new approach for HDR brachytherapy by directly optimizing the dose distribution based on dosimetric criteria.
  
  
  METHODS
  The authors developed inverse planning by integer program (IPIP), an optimization model for computing HDR brachytherapy dose plans and a fast heuristic for it. They used their heuristic to compute dose plans for 20 anonymized prostate cancer image data sets from patients previously treated at their clinic database. Dosimetry was evaluated and compared to dosimetric criteria.
  
  
  RESULTS
  Dose plans computed from IPIP satisfied all given dosimetric criteria for the target and healthy tissue after a single iteration. The average target coverage was 95%. The average computation time for IPIP was 30.1 s on an Intel(R) Core 2 Duo CPU 1.67 GHz processor with 3 Gib RAM.
  
  
  CONCLUSIONS
  IPIP is an HDR brachytherapy planning system that directly incorporates dosimetric criteria. The authors have demonstrated that IPIP has clinically acceptable performance for the prostate cases and dosimetric criteria used in this study, in both dosimetry and runtime. Further study is required to determine if IPIP performs well for a more general group of patients and dosimetric criteria, including other cancer sites such as GYN.
authors.affiliation: Department of Civil and Environmental Engineering, University of California, Berkeley, 760 Davis Hall, Berkeley, California 94720-1710, USA. timmy.siauw@gmail.com
authors.forename: Timmy
authors.initials: T
authors.lastname: Siauw
authors.forename: Adam
authors.initials: A
authors.lastname: Cunha
authors.forename: Alper
authors.initials: A
authors.lastname: Atamtürk
authors.forename: I-Chow
authors.initials: IC
authors.lastname: Hsu
authors.forename: Jean
authors.initials: J
authors.lastname: Pouliot
authors.forename: Ken
authors.initials: K
authors.lastname: Goldberg
mesh_terms: D001918:Brachytherapy / Q000379:methods*; D003198:Computer Simulation; D006801:Humans; D008297:Male; D008954:Models, Biological; D015233:Models, Statistical; D011471:Prostatic Neoplasms / Q000532:radiotherapy*; D011874:Radiometry / Q000379:methods*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*