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Agarose-based Tissue Mimicking Optical Phantoms for Diffuse Reflectance Spectroscopy
Published on: August 22, 2018
Evaluation of quantitative (90)Y SPECT based on experimental phantom studies.
D Minarik1, K Sjögreen Gleisner, M Ljungberg
1Department of Medical Radiation Physics, Clinical Sciences Lund, Lund University, Sweden.
Physics in Medicine and Biology
|September 25, 2008
Summary
Accurate quantification in bremsstrahlung SPECT imaging of pure beta emitters like Yttrium-90 is challenging. Applying model-based compensations in reconstruction significantly improves activity quantification accuracy, enabling reliable dosimetry.
Area of Science:
- Medical Imaging
- Nuclear Medicine
- Radiotherapy Physics
Background:
- Pure beta emitters, such as Yttrium-90 ((90)Y), present complex spectra in SPECT imaging.
- This complexity increases demands on imaging protocols and reconstruction algorithms.
- Accurate quantitative SPECT imaging is crucial for dosimetry in targeted radionuclide therapy.
Purpose of the Study:
- To evaluate the quantitative accuracy of bremsstrahlung SPECT reconstruction.
- To implement and validate simulations of bremsstrahlung imaging using Monte Carlo methods.
- To assess the impact of various compensations on activity quantification in (90)Y SPECT.
Main Methods:
- Simulated bremsstrahlung photon spectra using MCNPX and SIMIND Monte Carlo programs.
- Validated simulations against experimental measurements using HPGe detectors and gamma cameras.
- Reconstructed SPECT images using OSEM algorithm with model-based attenuation, scatter, and collimator-detector response (CDR) compensations.
- Evaluated accuracy of total activity estimates in phantom inserts and a patient study.
Main Results:
- Simulations showed sufficient agreement with experimental measurements for generating scatter and CDR kernels.
- Reconstruction without compensations resulted in a bias of around -70% for large sources.
- Incorporating compensations reduced the bias to -10% to 16% for activity estimates.
- Feasibility was confirmed in a patient treated with (90)Y-Ibritumomab tiuxetan.
Conclusions:
- Accurate activity quantification in (90)Y bremsstrahlung SPECT is achievable with proper reconstruction compensations.
- Model-based attenuation, scatter, and CDR compensations are essential for reliable dosimetry.
- This approach enhances the clinical utility of SPECT imaging for pure beta emitters.
