Purpose: To perform the largest in vivo dosimetry study for interstitial brachytherapy yet to be undertaken using a new radiophotoluminescence glass dosimeter (RPLGD) in patients with pelvic malignancy and to study the limits of contemporary planning software based on the results. Patients and Methods: Sixty-six patients with pelvic malignancy were treated with high-dose-rate interstitial brachytherapy, including prostate (n = 26), gynecological (n = 35), and miscellaneous (n = 5). Doses for a total of 1004 points were measured by RPLGDs and calculated with planning software in the following locations: rectum (n = 549), urethra (n = 415), vagina (n = 25), and perineum (n = 15). Compatibility (measured dose/calculated dose) was analyzed according to dosimeter location. Results: The compatibility for all dosimeters was 0.98 ± 0.23, stratified by location: rectum, 0.99 ± 0.20; urethra, 0.96 ± 0.26; vagina, 0.91 ± 0.08; and perineum, 1.25 ± 0.32. Conclusions: Deviations between measured and calculated doses for the rectum and urethra were greater than 20%, which is attributable to the independent movements of these organs and the applicators. Missing corrections for inhomogeneity are responsible for the 9% negative shift near the vaginal cylinder (specific gravity = 1.24), whereas neglect of transit dose contributes to the 25% positive shift in the perineal dose. Dose deviation of >20% for nontarget organs should be taken into account in the planning process. Further development of planning software and a real-time dosimetry system are necessary to use the current findings and to achieve adaptive dose delivery.
|Original language||English (US)|
|Number of pages||8|
|Journal||International Journal of Radiation Oncology Biology Physics|
|State||Published - Feb 1 2008|
Bibliographical noteFunding Information:
The authors are grateful to Dr. Teizou Tomaru (Chiyoda Technol) and Mr. Tatsuya Ishikawa (Asahi Techno Glass) for their valued advice concerning radiation physics. This study was supported in part by a Grant-in-Aid for Scientific Research (C) from the Japan Society for the Promotion of Science (18591397). This study was presented at the 12th International Brachytherapy Conference, June 20–23, 2007, in Rome, Italy.
- High dose rate
- In vivo dosimetry
- Radiophotoluminescence glass dosimeter