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A Fast Online Replanning Algorithm Based on Intensity Field Projection for Adaptive Radiotherapy
Xiaomeng Liu1,2, Yueqiang Liang3, Jian Zhu4
1School of Medicine and Life Sciences, University of Jinan-Shandong Academy of Medical Sciences, Jinan, China.
Frontiers in Oncology
|March 21, 2020
Summary
Intensity Field Projection (IFP) is a novel online replanning algorithm that automatically adjusts radiation beam intensity distributions to correct for anatomical changes during treatment. This method significantly improves dose coverage and planning speed for lung cancer patients undergoing intensity modulated radiation therapy (IMRT).
Area of Science:
- Medical Physics
- Radiation Oncology
- Image-Guided Radiation Therapy
Background:
- Interfractional anatomical variations pose challenges in delivering precise radiation doses during intensity modulated radiation therapy (IMRT).
- Current online replanning strategies often require significant time, limiting their clinical applicability.
- Accurate and rapid adaptation of treatment plans is crucial for optimizing therapeutic outcomes and minimizing toxicity.
Purpose of the Study:
- To introduce the Intensity Field Projection (IFP) algorithm, an online replanning method designed for direct adjustment of beam intensity distributions.
- To evaluate the feasibility and efficacy of IFP in correcting interfractional anatomy variations within an acceptable time frame.
- To assess the impact of IFP on dose coverage for the clinical target volume (CTV) and organ at risk (OAR) doses in lung cancer patients.
Main Methods:
- IFP utilizes a gradient-based free form deformation (GFFD) algorithm to register planning CT and cone-beam CT images, generating a 3D deformation field.
- A 2D deformation field of ray intensity is derived from the 3D field, allowing for the adjustment of 2D ray intensity distributions for each beam.
- The method generates corresponding multi-leaf collimator (MLC) and jaw motion data, and was tested on 20 lung cancer IMRT cases.
Main Results:
- IFP plans demonstrated significantly improved CTV dose coverage (V100% and D95) compared to original and repositioning plans (p < 0.01).
- Mean total lung doses were comparable between IFP and conventional plans, indicating no significant increase in OAR toxicity.
- The entire IFP replanning process was completed within an average of 3 minutes, highlighting its rapid execution.
Conclusions:
- The IFP algorithm offers an effective online replanning strategy for automatically correcting interfractional anatomy variations in IMRT.
- IFP substantially increases planning speed, making it a promising tool for online adaptive radiotherapy.
- Preliminary results suggest IFP can enhance treatment precision and efficiency in lung cancer radiotherapy.
