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Published on: October 18, 2011
On-line implant reconstruction in HDR brachytherapy
Inger-Karine K Kolkman-Deurloo1, Wilhelmus J M de Kruijf, Peter C Levendag
1Department of Radiation Oncology, Erasmus MC-Daniel den Hoed Cancer Center, Rotterdam, The Netherlands. i.kolkman-deurloo@erasmusmc.nl
Summary
Accurate on-line brachytherapy planning is achievable with dedicated image distortion correction algorithms in the Integrated Brachytherapy Unit (IBU). This method minimizes deviations in treatment time and dose, meeting clinical requirements.
Area of Science:
- Medical Physics
- Radiation Oncology
- Medical Imaging
Background:
- Brachytherapy requires accurate implant reconstruction for precise radiation delivery.
- Image distortion in the Integrated Brachytherapy Unit (IBU) can affect treatment planning accuracy.
- Dedicated algorithms are needed to correct for geometric and magnetic distortions.
Purpose of the Study:
- To evaluate the accuracy of on-line planning in an IBU using image distortion correction algorithms.
- To assess the impact of reconstruction accuracy on clinical treatment plans, specifically treatment time and dose deviations.
- To validate the effectiveness of separate geometric and magnetic distortion correction.
Main Methods:
- Reconstruction accuracy was measured using 20 markers in a QA phantom.
- Treatment plans of phantoms and three patients were compared with reference plans.
- On-line reconstruction with image distortion correction was implemented and evaluated.
Main Results:
- Average reconstruction error was reduced significantly after image distortion correction (e.g., 15-inch images reduced from 0.8 mm to 0.0 mm).
- Deviations in calculated treatment time were reduced from a maximum of 2.7% to less than 0.8%.
- Patient-specific on-line plans showed deviations smaller than 0.3% in treatment time and dose.
Conclusions:
- Accurate on-line implant reconstruction is feasible using the IBU localiser and dedicated correction algorithms.
- The results meet the minimum requirements set by the Netherlands Commission on Radiation Dosimetry (NCS).
- Limitations include a restriction on C-arm angles for which magnetic distortion corrections are available.
