Related Experiment Videos
Defining a radiotherapy target with positron emission tomography.
Quinten C Black1, Inga S Grills, Larry L Kestin
121st Century Oncology, Inc., Asheville, NC, USA.
International Journal of Radiation Oncology, Biology, Physics
|November 3, 2004
Summary
A new method uses a regression function to define gross tumor volume (GTV) with F-18 fluorodeoxyglucose positron emission tomography (FDG-PET) imaging. This approach improves accuracy for non-small-cell lung cancer (NSCLC) radiotherapy planning compared to fixed thresholds.
Area of Science:
- Nuclear Medicine
- Radiotherapy Oncology
- Medical Imaging Analysis
Background:
- F-18 fluorodeoxyglucose positron emission tomography (FDG-PET) is crucial for staging various cancers, including non-small-cell lung cancer (NSCLC).
- Current radiotherapy gross tumor volume (GTV) definition relies heavily on computed tomography (CT) data, potentially missing FDG-PET information.
- A standardized method for FDG-PET-based GTV definition is needed to improve radiotherapy accuracy.
Purpose of the Study:
- To develop and validate an accurate and uniformly applicable method for defining gross tumor volume (GTV) using FDG-PET imaging.
- To establish a model-based threshold for FDG-PET GTV definition that accounts for variations in standardized uptake value (SUV).
Main Methods:
- A phantom study was conducted using glass spheres of varying volumes and FDG concentrations within a background bath.
- A model-based method determined a unique cutoff standardized uptake value (SUV) for FDG-PET GTV definition.
- The influence of mean target SUV, background FDG concentration, and target volume on GTV definition was evaluated. A linear regression function was derived and applied to both phantom and NSCLC patient data.
Main Results:
- A strong linear relationship was found between the threshold SUV and mean target SUV (threshold SUV = 0.307 x mean target SUV + 0.588).
- The regression function resulted in significantly smaller deviations in volume estimation compared to a fixed image intensity threshold, both in phantoms (21% difference) and NSCLC patients (67% difference).
- Background concentration and target volume indirectly influenced threshold SUV via their effect on mean target SUV.
Conclusions:
- A systematic method for defining FDG-PET-based GTV using a regression-derived threshold SUV is feasible.
- The threshold SUV is highly dependent on the mean target SUV and can be determined through an iterative process.
- This approach offers improved accuracy for GTV definition in NSCLC radiotherapy planning.