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Accuracy of 177Lu activity quantification in SPECT imaging: a phantom study
Carlos F Uribe1,2,3, Pedro L Esquinas4,5, Jesse Tanguay4
1Medical Imaging Research Group, Department of Radiology, University of British Columbia, Vancouver, British Colombia, Canada. curibe@bccrc.ca.
EJNMMI Physics
|January 8, 2017
Summary
Accurate activity quantification in 177Lu SPECT/CT studies is achievable following Medical Internal Radiation Dose (MIRD) guidelines. However, improved organ and tumor segmentation techniques are needed for enhanced accuracy.
Area of Science:
- Nuclear Medicine
- Medical Imaging
- Radiopharmaceutical Therapy
Background:
- Assessing activity quantification accuracy in 177Lu SPECT/CT studies.
- Evaluating scatter correction and segmentation methods against Medical Internal Radiation Dose (MIRD) recommendations.
Purpose of the Study:
- Compare two scatter correction and three segmentation methods for 177Lu quantification.
- Evaluate tomographic vs. planar methods for camera normalization factor (CNF) determination.
Main Methods:
- Utilized Siemens SymbiaT SPECT/CT with 177Lu phantoms in various media.
- Reconstructed images using SPEQToR software with resolution recovery, attenuation, and scatter correction (APDI, TEW).
- Compared segmentation methods: fixed threshold, CT-based, and iterative adaptive dual thresholding (IADT).
Main Results:
- Triple Energy Window (TEW) scatter correction showed lower error (<6%) in air than Analytical Photon Distribution Interpolated (APDI) (<11%).
- APDI (<10%) outperformed TEW (<14%) in water; APDI with IADT yielded best results (<18% small objects, <5% large objects) in hot water.
- Planar and tomographic acquisitions provided similar CNF values, with planar being simpler.
Conclusions:
- Adherence to MIRD guidelines for data acquisition and reconstruction enables accurate activity quantification (<5% error for large objects).
- Further development of organ/tumor segmentation techniques is necessary for improved accuracy.
