Effect of Edema on Postimplant Dosimetry in Prostate Brachytherapy Using CT/MRI Fusion

Journal Article · Mon Oct 01 04:00:00 EDT 2007 · International Journal of Radiation Oncology, Biology and Physics

DOI:https://doi.org/10.1016/j.ijrobp.2007.05.082· OSTI ID:21036267

Tanaka, Osamu ^[1]; Hayashi, Shinya; Matsuo, Masayuki ^[1]; Nakano, Masahiro; Uno, Hiromi ^[2]; Ohtakara, Kazuhiro ^[1]; Miyoshi, Toshiharu ^[3]; Deguchi, Takashi ^[2]; Hoshi, Hiroaki ^[1]

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1. Department of Radiology, Gifu University School of Medicine, Gifu (Japan)
2. Department of Urology, Gifu University School of Medicine, Gifu (Japan)
3. Division of Radiation Oncology, Gifu University Hospital, Gifu City (Japan)

Purpose: To investigate the time course of prostatic edema and the effect on the dose-volume histograms of the prostate for patients treated with brachytherapy. Methods and Materials: A total of 74 patients with prostate cancer were enrolled in this prospective study. A transrectal ultrasound-based preplan was performed 4 weeks before implantation and computed tomography/magnetic resonance imaging fusion-based postimplant dosimetry was performed on the day after implantation (Day 1) and 30 days after implantation (Day 30). The prostate volume, prostate volume covered by 100% of the prescription dose (V{sub 100}), and dose covering 90% of the prostate (D{sub 90}) were evaluated with prostatic edema over time. Results: Prostatic edema was greatest on Day 1, with the mean prostate volume 36% greater than the preplan transrectal ultrasound-based volume; it thereafter decreased over time. It was 9% greater than preplan volume on Day 30. The V{sub 100} increased 5.7% from Day 1 to Day 30, and the D{sub 90} increased 13.1% from Day 1 to Day 30. The edema ratio (postplan/preplan) on Day 1 of low-quality implants with a V{sub 100} of <80% was significantly greater than that of intermediate- to high-quality implants (>80% V{sub 100}; p = 0.0272). The lower V{sub 100} on Day 1 showed a greater increase from Day 1 to Day 30. A V{sub 100} on Day 1 of >92% is unlikely to increase >0% during the interval studied. Conclusion: Low-quality implants on Day 1 were highly associated with edema; however, such a low-quality implant on Day 1, with significant edema, tended to improve by Day 30. If a high-quality implant (V100 >92%) can be obtained on Day 1, a re-examination is no longer necessary.

• OSTI ID: 21036267
• Journal Information: International Journal of Radiation Oncology, Biology and Physics, Journal Name: International Journal of Radiation Oncology, Biology and Physics Journal Issue: 2 Vol. 69; ISSN IOBPD3; ISSN 0360-3016
• Country of Publication: United States
• Language: English

Related Subjects

62 RADIOLOGY AND NUCLEAR MEDICINE
BRACHYTHERAPY
CARCINOMAS
COMPUTERIZED TOMOGRAPHY
DOSIMETRY
EDEMA
NMR IMAGING
PATIENTS
PROSTATE
RADIATION DOSES
RADIATION SOURCE IMPLANTS