Sci-Sat AM(2): Brachy-07: Tomosynthesis-based seed reconstruction in LDR prostate brachytherapy: A clinical study

Area of Science:

• Medical Physics
• Radiotherapy
• Image Reconstruction

Background:

• Accurate seed placement is crucial for effective low-dose-rate (LDR) prostate brachytherapy.
• Post-implant dosimetry is essential for verifying dose coverage and identifying potential underdosage.

Purpose of the Study:

• To develop and validate a tomosynthesis-based procedure for rapid, post-implantation dose assessment of I-125 prostate seeds.
• To enable intraoperative adjustments for improved dose uniformity.

Main Methods:

• Reconstruction of seed positions using backprojection of 7 seed-only binary images over a 60° angle.
• 3D connected component analysis and statistical classification for seed extraction.
• Validation using phantom studies and a clinical study of 24 patients.

Main Results:

• Phantom study: Localization accuracy of 0.4±0.4 mm, leading to minimal dosimetric errors (D90: 0.5%, V100: 0.1%).
• Patient study: 96% automatic seed detection rate with <1.5% false positives.
• GUI-assisted correction achieved 100% detection in ~3 minutes.

Conclusions:

• Tomosynthesis offers a fast and accurate method for I-125 seed localization and dose assessment immediately after implantation.
• This technique facilitates intraoperative identification of underdosage and allows for timely correction, enhancing treatment efficacy and dose uniformity in prostate brachytherapy.