title: Optimization for high-dose-rate brachytherapy of cervical cancer with adaptive simulated annealing and gradient descent.
abstract: OBJECTIVE
  To validate an in-house optimization program that uses adaptive simulated annealing (ASA) and gradient descent (GD) algorithms and investigate features of physical dose and generalized equivalent uniform dose (gEUD)-based objective functions in high-dose-rate (HDR) brachytherapy for cervical cancer.
  
  
  METHODS
  Eight Syed/Neblett template-based cervical cancer HDR interstitial brachytherapy cases were used for this study. Brachytherapy treatment plans were first generated using inverse planning simulated annealing (IPSA). Using the same dwell positions designated in IPSA, plans were then optimized with both physical dose and gEUD-based objective functions, using both ASA and GD algorithms. Comparisons were made between plans both qualitatively and based on dose-volume parameters, evaluating each optimization method and objective function. A hybrid objective function was also designed and implemented in the in-house program.
  
  
  RESULTS
  The ASA plans are higher on bladder V75% and D2cc (p=0.034) and lower on rectum V75% and D2cc (p=0.034) than the IPSA plans. The ASA and GD plans are not significantly different. The gEUD-based plans have higher homogeneity index (p=0.034), lower overdose index (p=0.005), and lower rectum gEUD and normal tissue complication probability (p=0.005) than the physical dose-based plans. The hybrid function can produce a plan with dosimetric parameters between the physical dose-based and gEUD-based plans. The optimized plans with the same objective value and dose-volume histogram could have different dose distributions.
  
  
  CONCLUSIONS
  Our optimization program based on ASA and GD algorithms is flexible on objective functions, optimization parameters, and can generate optimized plans comparable with IPSA.
authors.affiliation: Department of Radiation Oncology, Rush University Medical Center, 500 S. Paulina Street, Chicago, IL.
authors.forename: Rui
authors.initials: R
authors.lastname: Yao
authors.affiliation: Department of Radiation Oncology, Rush University Medical Center, 500 S. Paulina Street, Chicago, IL.
authors.forename: Alistair K
authors.initials: AK
authors.lastname: Templeton
authors.affiliation: Department of Radiation Oncology, Rush University Medical Center, 500 S. Paulina Street, Chicago, IL.
authors.forename: Yixiang
authors.initials: Y
authors.lastname: Liao
authors.affiliation: Department of Radiation Oncology, Rush University Medical Center, 500 S. Paulina Street, Chicago, IL.
authors.forename: Julius V
authors.initials: JV
authors.lastname: Turian
authors.affiliation: Department of Radiation Oncology, Rush University Medical Center, 500 S. Paulina Street, Chicago, IL.
authors.forename: Krystyna D
authors.initials: KD
authors.lastname: Kiel
authors.affiliation: Department of Radiation Oncology, Rush University Medical Center, 500 S. Paulina Street, Chicago, IL. Electronic address: jchu@rush.edu.
authors.forename: James C H
authors.initials: JC
authors.lastname: Chu
mesh_terms: D000465:Algorithms; D001918:Brachytherapy / Q000379:methods*; D002294:Carcinoma, Squamous Cell / Q000532:radiotherapy*; D003661:Decision Support Techniques; D005260:Female; D006801:Humans; D058958:Organs at Risk; D011874:Radiometry; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D012007:Rectum; D016896:Treatment Outcome; D001743:Urinary Bladder; D002583:Uterine Cervical Neoplasms / Q000532:radiotherapy*
keywords: Adaptive simulated annealing; Equivalent uniform dose; HDR; Optimization; Volumetric brachytherapy