Technical Note: Rod phantom analysis for comparison of PET detector sampling and reconstruction methods.

Area of Science:

• Medical Imaging
• Nuclear Medicine
• Radiological Physics

Background:

• Positron Emission Tomography (PET) scanners aim for wide dynamic range performance.
• Clinical constraints like reduced injected dose and shorter scan times challenge optimal scanner performance.
• Maintaining image quality and quantitative accuracy under these constraints is crucial.

Purpose of the Study:

• Develop a methodology to assess PET scanner quantification performance.
• Compare performance metrics between two PET/CT scanners with different detector designs.
• Evaluate scanner performance under various imaging conditions and clinical constraints.

Main Methods:

• Utilized a dual phantom setup with resolution inserts for in-plane (x, y) and axial (z) resolution measurements.
• Compared two PET/CT systems with differing block detector crystal dimensions, including one with thinner slices.
• Derived and compared quantitative measures such as contrast recovery, max/min values, and feature profile accuracy.

Main Results:

• The scanner with thinner slices showed a 2% average performance improvement for a head-sized phantom, particularly with perpendicular rod alignment.
• This scanner exhibited a -1% performance decrease for a body-sized phantom, attributed to increased image noise.
• Differences in quantitative metrics between the two scanners were generally below 10%.

Conclusions:

• The proposed methodology highlights that smaller detector elements and more voxels necessitate higher count density for improved image quality and quantitation.
• In clinical body imaging, the benefits of advanced scanner designs must outweigh potential noise increases from lower count densities.
• Scanner design and clinical protocols significantly influence achievable quantitative performance.