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Dynamic Lung Tumor Tracking for Stereotactic Ablative Body Radiation Therapy
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Tumor tracking based on correlation models in scanned ion beam therapy: an experimental study
M Seregni1, R Kaderka, G Fattori
1Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, P.zza Leonardo da Vinci 32, I-20133 Milano, Italy.
Physics in Medicine and Biology
|June 19, 2013
Summary
Accurate radiation therapy for extra-cranial lesions needs tumor motion compensation. Integrating internal/external correlation models with an optical tracking system reduced targeting errors, improving dose delivery accuracy in most experiments.
Area of Science:
- Medical Physics
- Radiation Oncology
- Biomedical Engineering
Background:
- Accurate dose delivery in radiation therapy, particularly for extra-cranial lesions, necessitates effective tumor motion compensation.
- Real-time target position tracking, either via fluoroscopy or correlation models using external surrogates, is crucial for motion compensation.
Purpose of the Study:
- To integrate and evaluate two internal/external correlation models (state space and artificial neural network-based) within a custom infra-red optical tracking system (OTS).
- To assess the real-time accuracy and dosimetric impact of motion-compensated carbon ion beam delivery using these integrated models.
Main Methods:
- Developed and integrated state space and artificial neural network correlation models into an infra-red optical tracking system.
- Utilized a robotic breathing phantom to simulate regular and irregular internal target and external thorax motion.
- Measured external marker motion with the OTS to predict internal target position in real-time for dynamic beam steering.
Main Results:
- The integrated correlation models achieved a transversal (2D) targeting error consistently below 1.3 mm (root mean square).
- A significant reduction in dosimetric error compared to uncompensated irradiation was observed in four out of six experimental scenarios.
- Identified phase shifts in motion as the most critical irregularity impacting the performance of external/internal correlation models.
Conclusions:
- The combination of internal/external correlation models and an optical tracking system offers a viable solution for real-time tumor motion compensation in radiation therapy.
- The system demonstrates potential for improving targeting accuracy and reducing dosimetric errors in carbon ion therapy.
- Further research is needed to address motion irregularities like phase shifts to optimize correlation model performance.
