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Automatic prostate localization on cone-beam CT scans for high precision image-guided radiotherapy
Monique H P Smitsmans1, Josien de Bois, Jan-Jakob Sonke
1Department of Radiation Oncology, The Netherlands Cancer Institute-Antoni van Leeuwenhoek Hospital (NKI-AVL), Amsterdam, The Netherlands.
International Journal of Radiation Oncology, Biology, Physics
|October 29, 2005
Summary
Automatic prostate localization using 3D gray-value registration (GR) on cone-beam CT (CBCT) is feasible. Collimating the field of view improves image quality and registration success rates, crucial for image-guided radiotherapy.
Area of Science:
- Medical Physics
- Radiotherapy
- Image Analysis
Background:
- An automatic 3D gray-value registration (GR) method was previously developed for prostate localization in image-guided radiotherapy.
- This method was initially tested on conventional computed tomography (CT) scans.
Purpose of the Study:
- To evaluate the performance of the automatic 3D GR algorithm for prostate localization on cone-beam CT (CBCT) scans.
- To assess the impact of collimated field of view (FOV) on CBCT image quality and registration accuracy.
Main Methods:
- 332 CBCT scans from 32 prostate cancer patients were analyzed.
- Automatic 3D GR was performed, with a fixed apex GR as a fallback for failed registrations.
- Registration success was visually assessed, and errors were quantified using calcifications.
Main Results:
- Collimated FOV CBCT scans showed a ~10% higher registration success rate compared to uncollimated scans.
- Using both normal and fixed apex GR improved success rates from 65% to 83% for collimated CBCT.
- Intrafraction motion artifacts from gas pockets were the primary cause of registration failures.
Conclusions:
- The 3D GR algorithm is feasible for automatic prostate localization on CBCT scans.
- Collimating the FOV during CBCT acquisition significantly enhances image quality and registration accuracy.
- CBCT is suitable for prostate position verification if intrafraction motion artifacts are minimized.