title: Inverse planning approach for 3-D MRI-based pulse-dose rate intracavitary brachytherapy in cervix cancer.
abstract: OBJECTIVE
  The purpose of this study was to evaluate the inverse planning simulated annealing (IPSA) software for the optimization of dose distribution in patients with cervix carcinoma treated with MRI-based pulsed-dose rate intracavitary brachytherapy.
  
  
  METHODS
  Thirty patients treated with a technique using a customized vaginal mold were selected. Dose-volume parameters obtained using the IPSA method were compared with the classic manual optimization method (MOM). Target volumes and organs at risk were delineated according to the Gynecological Brachytherapy Group/European Society for Therapeutic Radiology and Oncology recommendations. Because the pulsed dose rate program was based on clinical experience with low dose rate, dwell time values were required to be as homogeneous as possible. To achieve this goal, different modifications of the IPSA program were applied.
  
  
  RESULTS
  The first dose distribution calculated by the IPSA algorithm proposed a heterogeneous distribution of dwell time positions. The mean D90, D100, and V100 calculated with both methods did not differ significantly when the constraints were applied. For the bladder, doses calculated at the ICRU reference point derived from the MOM differed significantly from the doses calculated by the IPSA method (mean, 58.4 vs. 55 Gy respectively; p = 0.0001). For the rectum, the doses calculated at the ICRU reference point were also significantly lower with the IPSA method.
  
  
  CONCLUSIONS
  The inverse planning method provided fast and automatic solutions for the optimization of dose distribution. However, the straightforward use of IPSA generated significant heterogeneity in dwell time values. Caution is therefore recommended in the use of inverse optimization tools with clinical relevance study of new dosimetric rules.
authors: Department of Radiotherapy, Brachytherapy Unit, Institut Gustave Roussy, Villejuif, France.
authors: Enrique
authors: E
authors: Chajon
authors: Isabelle
authors: I
authors: Dumas
authors: Mahmoud
authors: M
authors: Touleimat
authors: Nicolas
authors: N
authors: Magné
authors: Jérémy
authors: J
authors: Coulot
authors: Rodolfe
authors: R
authors: Verstraet
authors: Dimitri
authors: D
authors: Lefkopoulos
authors: Christine
authors: C
authors: Haie-Meder
mesh_terms: D000230:Adenocarcinoma / Q000532:radiotherapy; D000465:Algorithms; D001918:Brachytherapy / Q000295:instrumentation / Q000379:methods*; D018288:Carcinoma, Small Cell / Q000532:radiotherapy; D002294:Carcinoma, Squamous Cell / Q000532:radiotherapy; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods; D012007:Rectum / Q000528:radiation effects; D012984:Software; D001743:Urinary Bladder / Q000528:radiation effects; D002583:Uterine Cervical Neoplasms / Q000532:radiotherapy*