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Dynamic Lung Tumor Tracking for Stereotactic Ablative Body Radiation Therapy
Published on: June 7, 2015
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Prediction of lung tumor motion using nonlinear autoregressive model with exogenous input.
Kai Jiang1,2, Fumitake Fujii1,3, Takehiro Shiinoki4
1Graduate School of Science and Technology for Innovation, Yamaguchi University, 2-16-1, Tokiwa-dai, Ube 755-8611, Japan.
Physics in Medicine and Biology
|October 2, 2019
Summary
This study developed a lung tumor position predictor using a nonlinear autoregressive model with exogenous input (NARX) for dynamic tumor tracking radiotherapy. The NARX predictor accurately forecasts tumor movement, compensating for linear accelerator control lag.
Area of Science:
- Medical Physics
- Radiotherapy Technology
- Computational Biology
Background:
- Dynamic tumor tracking radiotherapy (DTT-RT) requires precise lung tumor localization.
- Commercial linear accelerators have a 50-500 ms positioning lag in multi-leaf collimator (MLC) control.
- Accurate prediction of future tumor positions is crucial for effective DTT-RT.
Purpose of the Study:
- To develop and evaluate a lung tumor position predictor for DTT-RT.
- To compensate for MLC positioning lag using predictive modeling.
- To assess the feasibility of generating future gating cubes for DTT-RT.
Main Methods:
- A nonlinear autoregressive model with exogenous input (NARX) was employed.
- Patient-specific NARX models were trained using lung tumor motion trajectories.
- Three prediction horizons (600 ms, 800 ms, 1 s) were investigated.
- Performance metrics included RMS prediction errors and trajectory coverage rates.
Main Results:
- The NARX predictor demonstrated effective lung tumor motion prediction.
- Rates of coverage for the entire tumor trajectory were high across prediction horizons.
- Mean coverage rates were [Formula: see text]%, [Formula: see text]%, and [Formula: see text]% for 600 ms, 800 ms, and 1 s horizons, respectively.
Conclusions:
- The proposed NARX predictor is a viable tool for lung tumor position prediction in DTT-RT.
- The predictor effectively compensates for MLC positioning lag.
- This approach enhances the feasibility of implementing DTT-RT by enabling accurate gating cube generation.

