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PET motion compensation for radiation therapy using a CT-based mid-position motion model: methodology and clinical
Matthijs F Kruis1, Jeroen B van de Kamer, Antonetta C Houweling
1Department of Radiation Oncology, The Netherlands Cancer Institute, Antoni van Leeuwenhoek Hospital, Amsterdam, The Netherlands.
Summary
Motion-compensated 4D PET scans improve image quality for radiation therapy planning. This technique enhances quantitative data for pulmonary lesions by reducing motion artifacts and improving uptake values and volumes.
Area of Science:
- Medical Imaging
- Radiotherapy Physics
- Nuclear Medicine
Background:
- Four-dimensional positron emission tomography (4D PET) offers improved thoracic imaging but faces challenges in radiation therapy planning due to low signal-to-noise ratio in individual frames.
- Current systems lack 4D PET plan optimization capabilities, hindering its full potential in clinical applications.
- Motion artifacts in 4D PET reduce image quality and quantitative accuracy, impacting treatment planning.
Purpose of the Study:
- To implement and evaluate a method for constructing motion-compensated 3D PET scans at the mid-position.
- To utilize a 4D computed tomography (CT)-derived motion model for motion compensation in 4D PET.
- To assess the impact of this technique on image quality and quantitative accuracy for radiation therapy planning.
Main Methods:
- Registered all voxels of 4D PET data to a time-averaged position using a motion model derived from 4D CT frames.
- Summed registered scans to create a motion-compensated 3D mid-position PET scan.
- Validated the method using phantom datasets and data from 27 lung cancer patients.
Main Results:
- PET motion compensation significantly improved image quality in both phantoms and patients, evidenced by increased maximum standardized uptake value (SUVmax) and decreased apparent volumes.
- In homogeneous phantom data, the amplitude-to-diameter ratio strongly correlated with the method's effectiveness.
- In heterogeneous patient data, motion amplitude was a better predictor; large amplitudes led to up to 25% SUVmax increase and 10% reduction in 50% SUVmax volume diameter.
Conclusions:
- 4D CT-based motion-compensated mid-position PET scans yield superior quantitative data, including uptake values and volumes at the time-averaged position.
- This improved data facilitates more accurate radiation therapy treatment planning for pulmonary lesions.
- The technique effectively addresses motion artifacts, enhancing the diagnostic and therapeutic utility of 4D PET.
