Prospective Clinical Trial of Bladder Filling and Three-Dimensional Dosimetry in High-Dose-Rate Vaginal Cuff Brachytherapy

Alexandra J. Stewart, Robert A. Cormack, Hang Lee, Li Xiong, Jorgen L. Hansen, Desmond A. O'Farrell, Akila N. Viswanathan

Research output: Contribution to journalArticlepeer-review

Abstract

Purpose: To investigate the effect of bladder filling on dosimetry and to determine the best bladder dosimetric parameter for vaginal cuff brachytherapy. Methods and Materials: In this prospective clinical trial, a total of 20 women underwent vaginal cylinder high-dose-rate brachytherapy. The bladder was full for Fraction 2 and empty for Fraction 3. Dose-volume histogram and dose-surface histogram values were generated for the bladder, rectum, and urethra. The midline maximal bladder point (MBP) and the midline maximal rectal point were recorded. Paired t tests, Pearson correlations, and regression analyses were performed. Results: The volume and surface area of the irradiated bladder were significantly smaller when the bladder was empty than when full. Of the several dose-volume histogram and dose-surface histogram parameters evaluated, the bladder maximal dose received by 2 cm3 of tissue, volume of bladder receiving ≥50% of the dose, volume of bladder receiving ≥70% of the dose, and surface area of bladder receiving ≥50% of the dose significantly predicted for the difference between the empty vs. full filling state. The volume of bladder receiving ≥70% of the dose and the maximal dose received by 2 cm3 of tissue correlated significantly with the MBP. Bladder filling did not alter the volume or surface area of the rectum irradiated. However, an empty bladder did result in the nearest point of bowel being significantly closer to the vaginal cylinder than when the bladder was full. Conclusions: Patients undergoing vaginal cuff brachytherapy treated with an empty bladder have a lower bladder dose than those treated with a full bladder. The MBP correlated well with the volumetric assessments of bladder dose and provided a noninvasive method for reporting the MBP dose using three-dimensional imaging. The MBP can therefore be used as a surrogate for complex dosimetry in the clinic.

Original languageEnglish (US)
Pages (from-to)843-848
Number of pages6
JournalInternational Journal of Radiation Oncology Biology Physics
Volume72
Issue number3
DOIs
StatePublished - Nov 1 2008
Externally publishedYes

Keywords

  • Computed tomography bladder dosimetry
  • Vaginal cuff brachytherapy

ASJC Scopus subject areas

  • Radiation
  • Oncology
  • Radiology Nuclear Medicine and imaging
  • Cancer Research

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