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Improved dosimetry for targeted radionuclide therapy using nonrigid registration on sequential SPECT images
Edwin C I Ao1, Nien-Yun Wu2, Shyh-Jen Wang3
1Biomedical Imaging Laboratory, Department of Electrical and Computer Engineering, Faculty of Science and Technology, University of Macau, Macau SAR, China.
Medical Physics
|February 6, 2015
Summary
Nonrigid image registration significantly improves 3D dosimetry accuracy for targeted radionuclide therapy (TRT) by correcting patient movement and organ deformation in quantitative SPECT (QSPECT) scans.
Area of Science:
- Medical Imaging
- Nuclear Medicine
- Radiotherapy Physics
Background:
- Accurate 3D dosimetry is crucial for targeted radionuclide therapy (TRT).
- Serial nuclear medicine scans used in TRT are prone to misalignment due to patient movement and organ deformation.
- Image misalignment can reduce the accuracy of voxel-level dosimetry.
Purpose of the Study:
- To implement and evaluate nonrigid image registration for quantitative SPECT (QSPECT) images in TRT dosimetry.
- To assess the impact of nonrigid registration on dosimetric accuracy in the presence of simulated patient movement and organ deformation.
Main Methods:
- Generated 4D extended cardiac torso phantoms with In-111 Zevalin biokinetics and anatomical variations.
- Simulated QSPECT acquisitions at five time points with modeled organ and body deformation.
- Reconstructed QSPECT images using OS-EM with corrections and applied organ-based nonrigid registration.
- Calculated cumulative activity, dose distributions, and analyzed dose-volume histograms (DVHs).
Main Results:
- Nonrigid registration improved mean organ dose differences from -15.50% to -2.12% for the spleen and -7.28% to -0.23% for the liver.
- Cumulative DVHs showed improvement across all organs after nonrigid registration.
- Normalized absolute errors for differential DVHs ranged from 6.79% to 39.70% depending on the organ and segmentation method.
Conclusions:
- Nonrigid registration of sequential QSPECT images is a feasible technique for TRT.
- This method enhances the accuracy of 3D dosimetry in targeted radionuclide therapy.
