A surrogate urethra for real-time planning of high-dose-rate prostate brachytherapy
| Autor: | Audrey Tetreault-LaFlamme, Francois Bachand, Michelle Hilts, Steven Tisseverasinghe, Deidre Batchelar, Heather Halperin, Juanita Crook |
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| Rok vydání: | 2019 |
| Předmět: |
Male
Organs at Risk medicine.medical_treatment Brachytherapy Radiation Dosage 030218 nuclear medicine & medical imaging 03 medical and health sciences Dose limit 0302 clinical medicine Urethra Prostatic urethra medicine Dosimetry Humans Radiology Nuclear Medicine and imaging Radiation Injuries Radiometry Retrospective Studies Ultrasonography business.industry Radiotherapy Planning Computer-Assisted Ultrasound Prostate Prostatic Neoplasms Radiotherapy Dosage medicine.anatomical_structure Cross-Sectional Studies Oncology 030220 oncology & carcinogenesis Nuclear medicine business Dose rate Prostate brachytherapy |
| Zdroj: | Brachytherapy. 18(5) |
| ISSN: | 1873-1449 |
| Popis: | Purpose This study characterizes prostatic urethra cross-section to develop a surrogate urethra for accurate prediction of urethral dose during real-time high-dose-rate prostate brachytherapy. Materials and Methods Archived preoperative transrectal ultrasound images from 100 patients receiving low-dose-rate prostate brachytherapy were used to characterize the prostatic urethra, contoured on ultrasound using aerated gel. Consensus contours, defined using majority vote, described commonalities in cross-sectional shape across patients. Potential simplified surrogates were defined and evaluated against the true urethra. The best performing surrogate, a circle of varying size (CS) was retrospectively contoured on 85 high-dose-rate prostate brachytherapy treatment plans. Dose to this recommended surrogate was compared with urethral doses estimated by the standard 6 mm circle surrogate. Results Clear variation in urethral cross-sectional shape was observed along its length and between patients. The standard circle surrogate had low predictive sensitivity (61.1%) compared with true urethra because of underrepresentation of the verumontanum midgland. The CS best represented the true urethra across all validation metrics (dice: 0.73, precision: 67.0%, sensitivity: 83.2%, conformity: 0.78). Retrospective evaluation of planned doses using the CS surrogate resulted in significant differences in all reported urethral dose parameters compared with the standard circle, with the exception of D100%. The urethral dose limit (115%) was exceeded in 40% of patients for the CS surrogate. Conclusions The proposed CS surrogate, consisting of circles of varying diameter, is simple yet better represents the true urethra compared with the standard 6 mm circle. Higher urethral doses were predicted using CS, and the improved accuracy of CS may offer increased predictive power for urethral toxicity, a subject of future work. |
| Databáze: | OpenAIRE |
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