title: A dosimetric analysis of intensity-modulated radiation therapy (IMRT) as an alternative to adjuvant high-dose-rate (HDR) brachytherapy in early endometrial cancer patients.
abstract: OBJECTIVE
  To evaluate the role of intensity-modulated radiation treatment (IMRT) as an alternative to high-dose-rate (HDR) brachytherapy in the treatment of the vagina in postoperative early endometrial cancer patients after surgery.
  
  
  METHODS
  Planning computed tomography (CT) scans of 10 patients previously treated with HDR were used in this study. In all cases, a dose of 700 cGy/fraction was prescribed at a distance of 0.5 cm from the cylinder surface. The same CT scans were then used in IMRT planning. In this paradigm, the vaginal cylinder represents a component of a hypothetical immobilization system that would be indexed to the linac treatment table.
  
  
  RESULTS
  Our study showed that IMRT provided relatively lower rectal doses than HDR when treatment was prescribed at a distance of 0.5 cm away from the cylinder surface. Maximum rectal doses were lower with IMRT compared with HDR (average: 89.0% vs. 142.6%, respectively, p < 0.05). Moreover, the mean rectal dose was lower in IMRT plans compared with HDR plans with treatment prescribed either to the surface (average: 14.8% vs. 21.4%, respectively, p < 0.05) or to 0.5 cm (average: 19.6% vs. 33.5%, respectively, p < 0.05). IMRT plans had planning target volume (PTV) coverage comparable with HDR (average PTV minimum for treatment prescribed to 0.5 cm: 93.9% vs. 92.1%, p = 0.71, respectively) with less inhomogeneity (average PTV maximum: 110.8% vs. 381.6%, p < 0.05).
  
  
  CONCLUSIONS
  Our dosimetric analysis suggests that when used in conjunction with a suitable immobilization system, IMRT may provide an alternative to HDR brachytherapy in women with early endometrial cancer after hysterectomy. However, more studies are needed to evaluate the clinical merit of the IMRT in these patients.
authors.affiliation: Department of Radiation and Cellular Oncology, The University of Chicago, Chicago, IL 60637, USA. baydogan@radonc.uchicago.edu
authors.forename: Bulent
authors.initials: B
authors.lastname: Aydogan
authors.forename: Arno J
authors.initials: AJ
authors.lastname: Mundt
authors.forename: Brett D
authors.initials: BD
authors.lastname: Smith
authors.forename: Loren K
authors.initials: LK
authors.lastname: Mell
authors.forename: Steve
authors.initials: S
authors.lastname: Wang
authors.forename: Harold
authors.initials: H
authors.lastname: Sutton
authors.forename: John C
authors.initials: JC
authors.lastname: Roeske
mesh_terms: D001918:Brachytherapy; D016889:Endometrial Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D007044:Hysterectomy; D020714:Maximum Tolerated Dose; D009367:Neoplasm Staging; D011832:Radiation Injuries / Q000517:prevention & control*; D011879:Radiotherapy Dosage; D018714:Radiotherapy, Adjuvant / Q000379:methods; D050397:Radiotherapy, Intensity-Modulated / Q000379:methods* / Q000592:standards; D012007:Rectum / Q000528:radiation effects; D014057:Tomography, X-Ray Computed; D001743:Urinary Bladder / Q000528:radiation effects; D014621:Vagina