CT-based postimplant dosimetry of prostate brachytherapy: Comparison of 1-mm and 5-mm section CT

Osamu Tanaka, Shinya Hayashi, Masayuki Kanematsu, Masayuki Matsuo, Masahiro Nakano, Sunaho Maeda, Takashi Deguchi, Hiroaki Hoshi

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)


Purpose. The aim of this study was to compare the outcomes between 1-mm and 5-mm section computed tomography (CT)-based postimplant dosimetry. Materials and methods. A series of 21 consecutive patients underwent permanent prostate brachytherapy. The postimplant prostate volume was calculated using 1-mm and 5-mm section CT. One radiation oncologist contoured the prostate on CT images to obtain the reconstructed prostate volume (pVol), prostate V100 (percent of the prostate volume receiving at least the full prescribed dose), and prostate D90 (mean dose delivered to 90% of the prostate gland). The same radiation oncologist performed the contouring three times to evaluate intraobserver variation and subjectively scored the quality of the CT images. Results. The mean ±1 SD postimplant pVol was 20.17 ± 6.66 cc by 1-mm section CT and 22.24 ± 8.48 cc by 5-mm section CT; the difference in the mean values was 2.06 cc (P < 0.01). The mean postimplant prostate V 100 was 80.44% ± 7.06% by 1-mm section CT and 77.33% ± 10.22% by 5-mm section CT. The mean postimplant prostate D90 was 83.28% ± 10.81% by 1-mm section CT and 78.60% ± 15.75% by 5-mm section CT. In the evaluation of image quality, 5-mm section CT was assigned significantly higher scores than 1-mm section CT. In regard to intraobserver variation, 5-mm section CT revealed less intraobserver variation than 1-mm section CT. Conclusion. Our current results suggested that the outcomes of postimplant dosimetry using 1-mm section CT did not improved the results over those obtained using 5-mm section CT in terms of the quality of the CT image or reproducibility.

Original languageEnglish
Pages (from-to)22-26
Number of pages5
JournalRadiation Medicine - Medical Imaging and Radiation Oncology
Issue number1
Publication statusPublished - 01-01-2007
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Radiation
  • Radiology Nuclear Medicine and imaging
  • Oncology


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