title: Inverse planning simulated annealing for magnetic resonance imaging-based intracavitary high-dose-rate brachytherapy for cervical cancer.
abstract: OBJECTIVE
  To develop a technique using exclusively magnetic resonance imaging (MRI) to perform dwell position identification, targets and organs at risk delineation, and to apply inverse planning dose optimization to high-dose-rate brachytherapy for cervical cancer.
  
  
  METHODS
  We included 15 consecutive women treated with high-dose-rate (HDR) brachytherapy for cervical cancer. All patients underwent MRI after placement of tandem and ring applicator containing a gadodiamide-filled dummy marker. This technique allowed direct visualization of the source pathway and precise definition of the intra-applicator source positions. For each patient, we delineated gross target volume (GTV), high-risk clinical target volume (HR-CTV), and organs at risk on MRI, according to the European Gynecological GEC-ESTRO Working Group definitions. We performed inverse planning simulated annealing (IPSA) and analyzed the dose-volume histograms with the following endpoints: D(90), D(100), and V(100) for GTV and HR-CTV; D0.1 cc, D1 cc, D2 cc for bladder, rectum, and bowel; and dose at Point A.
  
  
  RESULTS
  The intra-applicator source pathway was easily visualized on MRI using the gadodiamide-filled marker. IPSA provided excellent target coverage. The mean D(90) and V(100) for HR-CTV were 103+/-5% and 92+/-3%, respectively. IPSA provided excellent bladder sparing. D1 cc and D2 cc of bladder were 73+/-10% and 67+/-10%, respectively.
  
  
  CONCLUSIONS
  We developed a novel technique that allows direct visualization of the intra-applicator source pathway on MRI. Using this technique, we successfully performed inverse planning directly from MRI.
authors.affiliation: Department of Radiation Medicine, Oregon Health and Science University, 3181 SW Sam Jackson Park Road, Portland, OR 97239, USA. charlottedai@gmail.com
authors.forename: Charlotte Dai
authors.initials: CD
authors.lastname: Kubicky
authors.forename: Benjamin M
authors.initials: BM
authors.lastname: Yeh
authors.forename: Etienne
authors.initials: E
authors.lastname: Lessard
authors.forename: Bonnie N
authors.initials: BN
authors.lastname: Joe
authors.forename: Joycelyn L
authors.initials: JL
authors.lastname: Speight
authors.forename: Jean
authors.initials: J
authors.lastname: Pouliot
authors.forename: I-Chow
authors.initials: IC
authors.lastname: Hsu
mesh_terms: D001918:Brachytherapy / Q000379:methods*; D003287:Contrast Media; D005260:Female; D019786:Gadolinium DTPA; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods; D012007:Rectum / Q000528:radiation effects; D012016:Reference Values; D001743:Urinary Bladder / Q000528:radiation effects; D002583:Uterine Cervical Neoplasms / Q000532:radiotherapy*
chemical_list: D003287:Contrast Media; C064925:gadodiamide; D019786:Gadolinium DTPA