title: A treatment planning and acute toxicity comparison of two pelvic nodal volume delineation techniques and delivery comparison of intensity-modulated radiotherapy versus volumetric modulated arc therapy for hypofractionated high-risk prostate cancer radiotherapy.
abstract: OBJECTIVE
  To perform a comparison of two pelvic lymph node volume delineation strategies used in intensity-modulated radiotherapy (IMRT) for high risk prostate cancer and to determine the role of volumetric modulated arc therapy (VMAT).
  
  
  METHODS
  Eighteen consecutive patients accrued to an ongoing clinical trial were identified according to either the nodal contouring strategy as described based on lymphotropic nanoparticle-enhanced magnetic resonance imaging technology (9 patients) or the current Radiation Therapy Oncology Group (RTOG) consensus guidelines (9 patients). Radiation consisted of 45 Gy to prostate, seminal vesicles, and lymph nodes, with a simultaneous integrated boost to the prostate alone, to a total dose of 67.5 Gy delivered in 25 fractions. Prospective acute genitourinary and gastrointestinal toxicities were compared at baseline, during radiotherapy, and 3 months after radiotherapy. Each patient was retrospectively replanned using the opposite method of nodal contouring, and plans were normalized for dosimetric comparison. VMAT plans were also generated according to the RTOG method for comparison.
  
  
  RESULTS
  RTOG plans resulted in a significantly lower rate of genitourinary frequency 3 months after treatment. The dosimetric comparison showed that the RTOG plans resulted in both favorable planning target volume (PTV) coverage and lower organs at risk (OARs) and integral (ID) doses. VMAT required two to three arcs to achieve adequate treatment plans, we did not observe consistent dosimetric benefits to either the PTV or the OARs, and a higher ID was observed. However, treatment times were significantly shorter with VMAT.
  
  
  CONCLUSIONS
  The RTOG guidelines for pelvic nodal volume delineation results in favorable dosimetry and acceptable acute toxicities for both the target and OARs. We are unable to conclude that VMAT provides a benefit compared with IMRT.
authors.affiliation: Department of Radiation Oncology, Sunnybrook Health Sciences Centre, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Sten
authors.initials: S
authors.lastname: Myrehaug
authors.forename: Gordon
authors.initials: G
authors.lastname: Chan
authors.forename: Tim
authors.initials: T
authors.lastname: Craig
authors.forename: Vivian
authors.initials: V
authors.lastname: Weinberg
authors.forename: Chun
authors.initials: C
authors.lastname: Cheng
authors.forename: Mack
authors.initials: M
authors.lastname: Roach
authors.forename: Patrick
authors.initials: P
authors.lastname: Cheung
authors.forename: Arjun
authors.initials: A
authors.lastname: Sahgal
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019583:Dose Fractionation, Radiation; D019983:Guideline Adherence; D006801:Humans; D008198:Lymph Nodes; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D053758:Nanoparticles; D058958:Organs at Risk; D010388:Pelvis; D017410:Practice Guidelines as Topic; D011446:Prospective Studies; D011467:Prostate / Q000473:pathology; D017430:Prostate-Specific Antigen / Q000097:blood; D011471:Prostatic Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D050397:Radiotherapy, Intensity-Modulated / Q000009:adverse effects / Q000379:methods*; D012007:Rectum; D012189:Retrospective Studies; D012306:Risk; D047368:Tumor Burden; D001743:Urinary Bladder
chemical_list: D017430:Prostate-Specific Antigen