title: Assessment of extended-field radiotherapy for stage IIIC endometrial cancer using three-dimensional conformal radiotherapy, intensity-modulated radiotherapy, and helical tomotherapy.
abstract: OBJECTIVE
  To perform a dosimetric comparison of three-dimensional conformal radiotherapy (3D-CRT), intensity-modulated radiotherapy (IMRT), and helical tomotherapy (HT) plans for pelvic and para-aortic RT in postoperative endometrial cancer patients; and to evaluate the integral dose (ID) received by critical structures within the radiation fields.
  
  
  METHODS
  We selected 10 patients with Stage IIIC endometrial cancer. For each patient, three plans were created with 3D-CRT, IMRT, and HT. The IMRT and HT plans were both optimized to keep the mean dose to the planning target volume (PTV) the same as that with 3D-CRT. The dosimetry and ID for the critical structures were compared. A paired two-tailed Student t test was used for data analysis.
  
  
  RESULTS
  Compared with the 3D-CRT plans, the IMRT plans resulted in lower IDs in the organs at risk (OARs), ranging from -3.49% to -17.59%. The HT plans showed a similar result except that the ID for the bowel increased 0.27%. The IMRT and HT plans both increased the IDs to normal tissue (see Table 1 and text for definition), pelvic bone, and spine (range, 3.31-19.7%). The IMRT and HT dosimetry showed superior PTV coverage and better OAR sparing than the 3D-CRT dosimetry. Compared directly with IMRT, HT showed similar PTV coverage, lower Ids, and a decreased dose to most OARs.
  
  
  CONCLUSIONS
  Intensity-modulated RT and HT appear to achieve excellent PTV coverage and better sparing of OARs, but at the expense of increased IDs to normal tissue and skeleton. HT allows for additional improvement in dosimetry and sparing of most OARs.
authors.affiliation: Department of Radiation Oncology, Cross Cancer Institute and University of Alberta, Edmonton, AB, Canada. jidong.lian@gmail.com
authors.forename: Jidong
authors.initials: J
authors.lastname: Lian
authors.forename: Marc
authors.initials: M
authors.lastname: Mackenzie
authors.forename: Kurian
authors.initials: K
authors.lastname: Joseph
authors.forename: Nadeem
authors.initials: N
authors.lastname: Pervez
authors.forename: George
authors.initials: G
authors.lastname: Dundas
authors.forename: Raul
authors.initials: R
authors.lastname: Urtasun
authors.forename: Robert
authors.initials: R
authors.lastname: Pearcey
mesh_terms: D016889:Endometrial Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D005260:Female; D005270:Femur Head; D006801:Humans; D007422:Intestines; D007668:Kidney; D009367:Neoplasm Staging; D011879:Radiotherapy Dosage; D020266:Radiotherapy, Conformal / Q000379:methods*; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods; D001743:Urinary Bladder