title: Benchmark Credentialing Results for NRG-BR001: The First National Cancer Institute-Sponsored Trial of Stereotactic Body Radiation Therapy for Multiple Metastases.
abstract: The NRG-BR001 trial is the first National Cancer Institute-sponsored trial to treat multiple (range 2-4) extracranial metastases with stereotactic body radiation therapy. Benchmark credentialing is required to ensure adherence to this complex protocol, in particular, for metastases in close proximity. The present report summarizes the dosimetric results and approval rates.
  
  
  
  The benchmark used anonymized data from a patient with bilateral adrenal metastases, separated by <5 cm of normal tissue. Because the planning target volume (PTV) overlaps with organs at risk (OARs), institutions must use the planning priority guidelines to balance PTV coverage (45 Gy in 3 fractions) against OAR sparing. Submitted plans were processed by the Imaging and Radiation Oncology Core and assessed by the protocol co-chairs by comparing the doses to targets, OARs, and conformity metrics using nonparametric tests.
  
  
  
  Of 63 benchmarks submitted through October 2015, 94% were approved, with 51% approved at the first attempt. Most used volumetric arc therapy (VMAT) (78%), a single plan for both PTVs (90%), and prioritized the PTV over the stomach (75%). The median dose to 95% of the volume was 44.8 ± 1.0 Gy and 44.9 ± 1.0 Gy for the right and left PTV, respectively. The median dose to 0.03 cm3was 14.2 ± 2.2 Gy to the spinal cord and 46.5 ± 3.1 Gy to the stomach. Plans that spared the stomach significantly reduced the dose to the left PTV and stomach. Conformity metrics were significantly better for single plans that simultaneously treated both PTVs with VMAT, intensity modulated radiation therapy, or 3-dimensional conformal radiation therapy compared with separate plans. No significant differences existed in the dose at 2 cm from the PTVs.
  
  
  
  Although most plans used VMAT, the range of conformity and dose falloff was large. The decision to prioritize either OARs or PTV coverage varied considerably, suggesting that the toxicity outcomes in the trial could be affected. Several benchmarks met the dose-volume histogram metrics but produced unacceptable plans owing to low conformity. Dissemination of a frequently-asked-questions document improved the approval rate at the first attempt. Benchmark credentialing was found to be a valuable tool for educating institutions about the protocol requirements.
authors.affiliation: Department of Radiation and Cellular Oncology, Chicago, Illinois. Electronic address: halhallaq@radonc.uchicago.edu.
authors.forename: Hania A
authors.initials: HA
authors.lastname: Al-Hallaq
authors.affiliation: Department of Radiation and Cellular Oncology, Chicago, Illinois.
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Chmura
authors.affiliation: Department of Radiation Oncology, Durham, North Carolina.
authors.forename: Joseph K
authors.initials: JK
authors.lastname: Salama
authors.affiliation: Imaging and Radiation Oncology Core Group (IROC) Houston, MD Anderson Cancer Center, Houston, Texas.
authors.forename: Jessica R
authors.initials: JR
authors.lastname: Lowenstein
authors.affiliation: Imaging and Radiation Oncology Core Group (IROC) PHILADELPHIA RT, Philadelphia, Pennsylvania.
authors.forename: Susan
authors.initials: S
authors.lastname: McNulty
authors.affiliation: Imaging and Radiation Oncology Core Group (IROC) PHILADELPHIA RT, Philadelphia, Pennsylvania.
authors.forename: James M
authors.initials: JM
authors.lastname: Galvin
authors.affiliation: Imaging and Radiation Oncology Core Group (IROC) Houston, MD Anderson Cancer Center, Houston, Texas.
authors.forename: David S
authors.initials: DS
authors.lastname: Followill
authors.affiliation: Department of Radiation Oncology, St Louis, Missouri.
authors.forename: Clifford G
authors.initials: CG
authors.lastname: Robinson
authors.affiliation: Department of Radiation Oncology, Rochester, Minnesota.
authors.forename: Thomas M
authors.initials: TM
authors.lastname: Pisansky
authors.affiliation: NRG Oncology Statistics and Data Management Center, Philadelphia, Pennsylvania.
authors.forename: Kathryn A
authors.initials: KA
authors.lastname: Winter
authors.affiliation: Department of Radiation Oncology, Columbus, Ohio.
authors.forename: Julia R
authors.initials: JR
authors.lastname: White
authors.affiliation: Imaging and Radiation Oncology Core Group (IROC) PHILADELPHIA RT, Philadelphia, Pennsylvania; Department of Radiation Oncology, Philadelphia, Pennsylvania.
authors.forename: Ying
authors.initials: Y
authors.lastname: Xiao
authors.affiliation: Department of Radiation Oncology, Ann Arbor, Michigan.
authors.forename: Martha M
authors.initials: MM
authors.lastname: Matuszak
mesh_terms: D000310:Adrenal Gland Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology / Q000532:radiotherapy* / Q000556:secondary*; D019985:Benchmarking / Q000592:standards* / Q000706:statistics & numerical data; D003406:Credentialing / Q000592:standards* / Q000706:statistics & numerical data; D019583:Dose Fractionation, Radiation; D006801:Humans; D054547:National Cancer Institute (U.S.); D058958:Organs at Risk / Q000000981:diagnostic imaging; D016634:Radiosurgery / Q000592:standards* / Q000706:statistics & numerical data; D011879:Radiotherapy Dosage / Q000592:standards; D011880:Radiotherapy Planning, Computer-Assisted / Q000592:standards* / Q000706:statistics & numerical data; D050397:Radiotherapy, Intensity-Modulated / Q000592:standards / Q000706:statistics & numerical data; D013116:Spinal Cord / Q000000981:diagnostic imaging; D013270:Stomach / Q000000981:diagnostic imaging; D047368:Tumor Burden; D014481:United States