title: Feasibility and Initial Dosimetric Findings for a Randomized Trial Using Dose-Painted Multiparametric Magnetic Resonance Imaging-Defined Targets in Prostate Cancer.
abstract: To compare dosimetric characteristics with multiparametric magnetic resonance imaging-identified imaging tumor volume (gross tumor volume, GTV), prostate clinical target volume and planning target volume, and organs at risk (OARs) for 2 treatment techniques representing 2 arms of an institutional phase 3 randomized trial of hypofractionated external beam image guided highly targeted radiation therapy.
  
  
  
  Group 1 (n=20) patients were treated before the trial inception with the standard dose prescription. Each patient had an additional treatment plan generated per the experimental arm. A total of 40 treatment plans were compared (20 plans for each technique). Group 2 (n=15) consists of patients currently accrued to the hypofractionated external beam image guided highly targeted radiation therapy trial. Plans were created as per the treatment arm, with additional plans for 5 of the group 2 experimental arm with a 3-mm expansion in the imaging GTV.
  
  
  
  For all plans in both patient groups, planning target volume coverage ranged from 95% to 100%; GTV coverage of 89.3 Gy for the experimental treatment plans ranged from 95.2% to 99.8%. For both groups 1 and 2, the percent volumes of rectum/anus and bladder receiving 40 Gy, 65 Gy, and 80 Gy were smaller in the experimental plans than in the standard plans. The percent volume at 1 Gy per fraction and 1.625 Gy per fraction were compared between the standard and the experimental arms, and these were found to be equivalent.
  
  
  
  The dose per fraction to the OARs can be made equal even when giving a large simultaneous integrated boost to the GTV. The data suggest that a GTV margin may be added without significant dose effects on the OARs.
authors.affiliation: Department of Radiation Oncology, University of Miami Miller School of Medicine, Miami, Florida. Electronic address: EBossart@med.miami.edu.
authors.forename: Elizabeth L
authors.initials: EL
authors.lastname: Bossart
authors.affiliation: Department of Radiation Oncology, University of Miami Miller School of Medicine, Miami, Florida.
authors.forename: Radka
authors.initials: R
authors.lastname: Stoyanova
authors.affiliation: Department of Radiation Oncology, University of California, Los Angeles, Los Angeles, California.
authors.forename: Kiri
authors.initials: K
authors.lastname: Sandler
authors.affiliation: Department of Radiation Oncology, University of Miami Miller School of Medicine, Miami, Florida.
authors.forename: Matthew
authors.initials: M
authors.lastname: Studenski
authors.affiliation: Department of Radiation Oncology, University of Miami Miller School of Medicine, Miami, Florida.
authors.forename: Amber
authors.initials: A
authors.lastname: Orman
authors.affiliation: Department of Radiation Oncology, University of Miami Miller School of Medicine, Miami, Florida.
authors.forename: Matthew
authors.initials: M
authors.lastname: Abramowitz
authors.affiliation: Department of Radiation Oncology, University of Miami Miller School of Medicine, Miami, Florida.
authors.forename: Alan
authors.initials: A
authors.lastname: Pollack
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D005240:Feasibility Studies; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D058958:Organs at Risk; D011471:Prostatic Neoplasms / Q000000981:diagnostic imaging / Q000532:radiotherapy*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D047368:Tumor Burden