title: Quality of Intensity Modulated Radiation Therapy Treatment Plans Using a ⁶⁰Co Magnetic Resonance Image Guidance Radiation Therapy System.
abstract: OBJECTIVE
  This work describes a commercial treatment planning system, its technical features, and its capabilities for creating (60)Co intensity modulated radiation therapy (IMRT) treatment plans for a magnetic resonance image guidance radiation therapy (MR-IGRT) system.
  
  
  METHODS
  The ViewRay treatment planning system (Oakwood Village, OH) was used to create (60)Co IMRT treatment plans for 33 cancer patients with disease in the abdominal, pelvic, thorax, and head and neck regions using physician-specified patient-specific target coverage and organ at risk (OAR) objectives. Backup plans using a third-party linear accelerator (linac)-based planning system were also created. Plans were evaluated by attending physicians and approved for treatment. The (60)Co and linac plans were compared by evaluating conformity numbers (CN) with 100% and 95% of prescription reference doses and heterogeneity indices (HI) for planning target volumes (PTVs) and maximum, mean, and dose-volume histogram (DVH) values for OARs.
  
  
  RESULTS
  All (60)Co IMRT plans achieved PTV coverage and OAR sparing that were similar to linac plans. PTV conformity for (60)Co was within <1% and 3% of linac plans for 100% and 95% prescription reference isodoses, respectively, and heterogeneity was on average 4% greater. Comparisons of OAR mean dose showed generally better sparing with linac plans in the low-dose range <20 Gy, but comparable sparing for organs with mean doses >20 Gy. The mean doses for all (60)Co plan OARs were within clinical tolerances.
  
  
  CONCLUSIONS
  A commercial (60)Co MR-IGRT device can produce highly conformal IMRT treatment plans similar in quality to linac IMRT for a variety of disease sites. Additional work is in progress to evaluate the clinical benefit of other novel features of this MR-IGRT system.
authors.affiliation: Department of Radiation Oncology, Washington University School of Medicine, St. Louis, Missouri. Electronic address: hwooten@radonc.wustl.edu.
authors.forename: H Omar
authors.initials: HO
authors.lastname: Wooten
authors.affiliation: Department of Radiation Oncology, Washington University School of Medicine, St. Louis, Missouri.
authors.forename: Olga
authors.initials: O
authors.lastname: Green
authors.affiliation: Department of Radiation Oncology, Washington University School of Medicine, St. Louis, Missouri.
authors.forename: Min
authors.initials: M
authors.lastname: Yang
authors.affiliation: Department of Radiation Oncology, Washington University School of Medicine, St. Louis, Missouri.
authors.forename: Todd
authors.initials: T
authors.lastname: DeWees
authors.affiliation: Department of Radiation Oncology, Washington University School of Medicine, St. Louis, Missouri.
authors.forename: Rojano
authors.initials: R
authors.lastname: Kashani
authors.affiliation: Department of Radiation Oncology, Washington University School of Medicine, St. Louis, Missouri.
authors.forename: Jeff
authors.initials: J
authors.lastname: Olsen
authors.affiliation: Department of Radiation Oncology, Washington University School of Medicine, St. Louis, Missouri.
authors.forename: Jeff
authors.initials: J
authors.lastname: Michalski
authors.affiliation: Department of Radiation Oncology, Washington University School of Medicine, St. Louis, Missouri.
authors.forename: Deshan
authors.initials: D
authors.lastname: Yang
authors.affiliation: Department of Radiation Oncology, Washington University School of Medicine, St. Louis, Missouri.
authors.forename: Kari
authors.initials: K
authors.lastname: Tanderup
authors.affiliation: Department of Radiation Oncology, Washington University School of Medicine, St. Louis, Missouri.
authors.forename: Yanle
authors.initials: Y
authors.lastname: Hu
authors.affiliation: Department of Radiation Oncology, Washington University School of Medicine, St. Louis, Missouri.
authors.forename: H Harold
authors.initials: HH
authors.lastname: Li
authors.affiliation: Department of Radiation Oncology, Washington University School of Medicine, St. Louis, Missouri.
authors.forename: Sasa
authors.initials: S
authors.lastname: Mutic
mesh_terms: D000008:Abdominal Neoplasms / Q000532:radiotherapy; D000465:Algorithms; D003037:Cobalt Radioisotopes / Q000627:therapeutic use*; D006258:Head and Neck Neoplasms / Q000532:radiotherapy; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000295:instrumentation* / Q000379:methods / Q000592:standards; D009010:Monte Carlo Method; D009369:Neoplasms / Q000532:radiotherapy*; D058958:Organs at Risk / Q000528:radiation effects; D010315:Particle Accelerators; D056888:Patient Positioning / Q000379:methods; D010386:Pelvic Neoplasms / Q000532:radiotherapy; D011832:Radiation Injuries / Q000517:prevention & control; D011879:Radiotherapy Dosage; D061089:Radiotherapy, Image-Guided / Q000295:instrumentation* / Q000379:methods / Q000592:standards; D050397:Radiotherapy, Intensity-Modulated / Q000295:instrumentation* / Q000379:methods / Q000592:standards; D013899:Thoracic Neoplasms / Q000532:radiotherapy
chemical_list: D003037:Cobalt Radioisotopes