Poster - Thurs Eve-14: Linking IGRT data with dose calculation for prostate IMRT planning
Medical Physics
|May 18, 2017
Summary
Accurate prostate cancer radiotherapy requires accounting for internal organ motion. Patient-specific probability distribution functions (PDFs) are crucial for evaluating delivered dose and ensuring treatment accuracy, unlike group PDFs.
Area of Science:
- Radiation Oncology
- Medical Physics
- Image-Guided Therapy
Background:
- Internal organ motion significantly impacts radiation dose delivery in prostate cancer treatment.
- Image-guided radiotherapy (IGRT) with implanted seeds allows for precise tracking of prostate motion.
Purpose of the Study:
- To investigate the impact of prostate motion on dose distribution in intensity-modulated radiotherapy (IMRT).
- To evaluate the effectiveness of patient-specific probability distribution functions (PDFs) versus group PDFs for treatment planning.
Main Methods:
- Studied 20 prostate patients undergoing IGRT with implanted gold seeds.
- Prostate motion was measured using MV EPI and compared to DRR.
- Treatment plans incorporated organ motion using patient-specific Gaussian PDFs.
Main Results:
- Dose reductions exceeding 5% were observed at the PTV edge in various directions for a subset of patients.
- 10% of patients experienced PTV doses below 95% of the prescription dose when using individual IGRT data.
- Group PDFs failed to accurately represent individual patient dose distributions, unlike patient-specific PDFs.
Conclusions:
- Static dose calculations are insufficient for assessing PTV coverage in the presence of organ motion.
- Incorporating patient-specific motion data is essential for accurate dose distribution and treatment planning.
- Patient-specific PDFs are vital for re-planning and assessing delivered dose accuracy in IGRT.
