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Narrow safety range of intraoperative rectal irradiation exposure volume for avoiding bleeding after seed implant brachytherapy.
- Source :
-
Radiation oncology (London, England) [Radiat Oncol] 2012 Jan 31; Vol. 7, pp. 15. Date of Electronic Publication: 2012 Jan 31. - Publication Year :
- 2012
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Abstract
- Background & Purpose: Rectal toxicity is less common after 125I seed implant brachytherapy for prostate cancer, and intraoperative rectal dose-volume constraints (the constraint) is still undetermined in pioneering studies. As our constraint failed to prevent grade 2 or 3 rectal bleeding (bled-pts) in 5.1% of patients, we retrospectively explored another constraint for the prevention of rectal bleeding.<br />Materials and Methods: The study population consisted of 197 patients treated with the brachytherapy as monotherapy using real-time intraoperative transrectal ultrasound (US)-guided treatment at a prescribed dose of 145 Gy. Post-implant dosimetry was performed on Day 1 and Day 30 after implantation using computed tomography (CT) imaging. Rectal bleeding toxicity was classified by CTC-AE ver. 3.0 during a mean 29-month (range, 12-48 months) period after implantation. The differences in rV100s were compared among intraoperative, Day 1 and Day 30 dosimetry, and between that of patients with grade 2 or 3 rectal bleeding (the bled-pts) and of the others (the spared-pts). All patients were divided into groups based on provisional rV100s that were increased stepwise in 0.1-cc increments from 0 to 1.0 cc. The difference in the ratios of the bled-pts to the spared-pts was tested by chi-square tests, and their odds ratios were calculated (bled-OR). All statistical analyses were performed by t-tests.<br />Results: The mean values of rV100us, rV100CT&#95;1, and rV100CT&#95;30 were 0.31 ± 0.43, 0.22 ± 0.36, and 0.59 ± 0.68 cc, respectively. These values temporarily decreased (p = 0.020) on Day 1 and increased (p = 0.000) on Day 30. There was no significant difference in rV100s between the bled-pts and spared-pts at any time of dosimetry. The maximum bled-OR was identified among patients with an rV100us value above 0.1 cc (p = 0.025; OR = 7.8; 95% CI, 1.4-145.8); an rV100CT&#95;1 value above 0.3 cc (p = 0.014; OR = 16.2; 95% CI, 3.9-110.7), and an rV100CT&#95;30 value above 0.5 cc (p = 0.019; OR = 6.3; 95% CI, 1.5-42.3).<br />Conclusion: By retrospective analysis exploring rV100 as intraoperative rectal dose-volume thresholds in 125I seed implant brachytherapy for prostate cancer, it is proved that rV100 should be less than 0.1 cc for preventing rectal bleeding.
- Subjects :
- Aged
Aged, 80 and over
Hemorrhage etiology
Humans
Intraoperative Period
Male
Middle Aged
Prognosis
Radiation Injuries etiology
Radiotherapy Planning, Computer-Assisted
Rectum diagnostic imaging
Retrospective Studies
Tomography, X-Ray Computed
Brachytherapy
Hemorrhage prevention & control
Iodine Radioisotopes therapeutic use
Prostatic Neoplasms radiotherapy
Prostheses and Implants
Radiation Injuries prevention & control
Rectum radiation effects
Subjects
Details
- Language :
- English
- ISSN :
- 1748-717X
- Volume :
- 7
- Database :
- MEDLINE
- Journal :
- Radiation oncology (London, England)
- Publication Type :
- Academic Journal
- Accession number :
- 22293400
- Full Text :
- https://doi.org/10.1186/1748-717X-7-15