Streak artifact reduction in filtered backprojection using a level line-based interpolation method

Area of Science:

• Medical Imaging
• Image Reconstruction
• Computational Imaging

Background:

• Filtered backprojection (FBP) algorithms can produce streak artifacts due to limited projection data.
• Conventional methods to reduce artifacts, like low-pass filtering, compromise image contrast and definition.

Purpose of the Study:

• To introduce a computational method, interpolation of projections by contouring (IPC), to increase projection data and reduce FBP artifacts.
• To evaluate the effectiveness of IPC in improving image quality in medical imaging.

Main Methods:

• The IPC process involves plotting level lines on sinograms to define isocount regions and interpolating points based on these regions.
• Data resampling increases the number of projections or pixels per projection.
• Phantom studies (bone scintigraphy) and a clinical case were used for comparison.

Main Results:

• Phantom studies demonstrated that IPC, by increasing projections by 2-3 times, yielded reconstructed slices closer to the true image.
• Clinical evaluation showed a reduction in streak artifacts, particularly in extracorporeal regions, even with a standard ramp filter.

Conclusions:

• The IPC process effectively reduces streak artifacts without requiring changes to acquisition protocols or operator intervention.
• Increasing projection numbers is crucial but insufficient; attenuation correction is necessary to fully mitigate artifacts with more projections.