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Non-uniformity measurements in PET
H J Ostertag1, J Doll, W K Kübler
1Deutsches Krebsforschungszentrum, Institut für Radiologie und Pathophysiologie, Heidelberg, Germany.
Medical Progress Through Technology
|January 1, 1991
Summary
This study measured positron tomograph non-uniformity using standard phantoms and procedures. Results show counting statistics significantly impact non-uniformity, especially at 2 million counts per image.
Area of Science:
- Medical Imaging
- Nuclear Medicine
- Positron Emission Tomography
Background:
- Performance evaluation of positron tomographs is crucial for accurate medical imaging.
- The European Commission (EC) established guidelines for positron tomograph performance assessment.
Purpose of the Study:
- To evaluate the non-uniformity of the Scanditronix PC 2048-7WB positron tomograph.
- To gain practical experience with EC-recommended performance evaluation procedures.
Main Methods:
- Non-uniformity was measured using cylindrical head and EC body phantoms.
- Emission scans collected 2 million counts per scan, following EC task group recommendations.
- The impact of varying counts and reconstruction filter width was assessed.
Main Results:
- Non-uniformity decreased with increased counts or wider reconstruction filters.
- Non-uniformity increased with the body phantom compared to the head phantom.
- Counting statistics were identified as the dominant factor in non-uniformity at approximately 2 million counts.
Conclusions:
- Positron tomograph non-uniformity is influenced by counting statistics and phantom size.
- Noise from larger attenuation lengths, not attenuation correction, caused increased non-uniformity in the body phantom.
- Measured non-uniformity values ranged approximately +/- 30%.