Comparison of urethral diameters for calculating the urethral dose after permanent prostate brachytherapy

Osamu Tanaka, Shinya Hayashi, Masayuki Matsuo, Masahiro Nakano, Yasuaki Kubota, Sunaho Maeda, Kazuhiro Ohtakara, Takashi Deguchi, Hiroaki Hoshi

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)


Purpose. No studies have yet evaluated the effects of a dosimetric analysis for different urethral volumes. We therefore evaluated the effects of a dosimetric analysis to determine the different urethral volumes. Methods. This study was based on computed tomography/magnetic resonance imaging (CT/MRI) combined findings in 30 patients who had undergone prostate brachytherapy. Postimplant CT/MRI scans were performed 30 days after the implant. The urethra was contoured based on its diameter (8, 6, 4, 2, and 0 mm). The total urethral volume-in cubic centimeters [UrV150/200(cc)] and percent (UrV150%/200%), of the urethra receiving 150% or 200% of the prescribed dose-and the doses (UrD90/30/5) in Grays to 90%, 30%, and 5% of the urethral volume were measured based on the urethral diameters. Results. The UrV150(cc) and UrD30 were statistically different between the of 8-, 6-, 4-, 2-, and 0-mm diameters, whereas the UrD5 was statistically different only between the 8-, 6-, and 4-mm diameters. Especially for UrD5, there was an approximately 40-Gy difference between the mean values for the 8- and 0-mm diameters. Conclusion. We recommend that the urethra should be contoured as a 4- to 6-mm diameter circle or one side of a triangle of 5-7 mm. By standardizing the urethral diameter, the urethral dose will be less affected by the total urethral volume.

Original languageEnglish
Pages (from-to)329-334
Number of pages6
JournalRadiation Medicine - Medical Imaging and Radiation Oncology
Issue number7
Publication statusPublished - 08-2007
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Radiation
  • Radiology Nuclear Medicine and imaging
  • Oncology

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