title: Can all centers plan intensity-modulated radiotherapy (IMRT) effectively? An external audit of dosimetric comparisons between three-dimensional conformal radiotherapy and IMRT for adjuvant chemoradiation for gastric cancer.
abstract: OBJECTIVE
  To compare dosimetric endpoints between three-dimensional conformal radiotherapy (3D-CRT) and intensity-modulated radiotherapy (IMRT) at our center with limited IMRT experience, and to perform an external audit of the IMRT plans.
  
  
  METHODS
  Ten patients, who received adjuvant chemoradiation for gastric cancer, formed the study cohort. For standardization, the planning target volume (PTV) and organs at risk were recontoured with the assistance of a study protocol radiologic atlas. The cohort was replanned with CMS Xio to generate coplanar 3D-CRT and IMRT plans. All 10 datasets, including volumes but without the plans (i.e., blinded), were transmitted to an experienced center where IMRT plans were designed using Nomos Corvus (IMRT-C) and ADAC Pinnacle (IMRT-P). All IMRT plans were normalized to D95% receiving 45 Gy.
  
  
  RESULTS
  Intensity-modulated radiotherapy yielded higher PTV V45 (volume that receives > or = 45 Gy) (p < 0.001) than 3D-CRT. No difference in V20 was seen in the right (p = 0.9) and left (p = 0.3) kidneys, but the liver mean dose (p < 0.001) was superior with IMRT. For the external audit, IMRT-C (p = 0.002) and IMRT-P (p < 0.001) achieved significantly lower left kidney V20 than IMRT, and IMRT-P (p < 0.001) achieved lower right kidney V20 than IMRT. The IMRT-C (p = 0.003) but not IMRT-P (p = 0.6) had lower liver mean doses than IMRT.
  
  
  CONCLUSIONS
  At our institution with early IMRT experience, IMRT improved PTV dose coverage and liver doses but not kidney doses. An external audit of IMRT plans showed that an experienced center can yield superior IMRT plans.
authors.affiliation: Department of Radiation Oncology, The Cancer Institute, National University Hospital, Singapore. hanstchung@gmail.com
authors.forename: Hans T
authors.initials: HT
authors.lastname: Chung
authors.forename: Brian
authors.initials: B
authors.lastname: Lee
authors.forename: Eileen
authors.initials: E
authors.lastname: Park
authors.forename: Jiade J
authors.initials: JJ
authors.lastname: Lu
authors.forename: Ping
authors.initials: P
authors.lastname: Xia
mesh_terms: D000328:Adult; D000368:Aged; D017024:Chemotherapy, Adjuvant / Q000592:standards / Q000706:statistics & numerical data; D054869:Clinical Audit; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011785:Quality Assurance, Health Care; D011874:Radiometry; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods / Q000592:standards*; D020266:Radiotherapy, Conformal / Q000592:standards* / Q000706:statistics & numerical data*; D012846:Singapore / Q000453:epidemiology; D013274:Stomach Neoplasms / Q000453:epidemiology* / Q000628:therapy*; D016896:Treatment Outcome