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A method for measuring the absolute sensitivity of positron emission tomographic scanners
D L Bailey1, T Jones, T J Spinks
1MRC Cyclotron Unit, Hammersmith Hospital, London, UK.
European Journal of Nuclear Medicine
|January 1, 1991
Summary
A new method accurately measures positron emission tomographic (PET) scanner absolute sensitivity in counts per second per megabecquerel. This technique overcomes limitations of traditional phantom measurements, enabling reliable scanner comparisons.
Area of Science:
- Medical Imaging Physics
- Nuclear Medicine Technology
- Positron Emission Tomography
Background:
- Current methods for measuring positron emission tomographic (PET) scanner absolute sensitivity are confounded by self-attenuation and scatter.
- These confounding factors hinder accurate absolute sensitivity measurements in counts per second per megabecquerel (counts.s-1.MBq-1).
- Inconsistent measurement practices impede meaningful comparisons between different PET scanner manufacturers and acquisition geometries.
Purpose of the Study:
- To develop and validate a novel method for measuring the absolute sensitivity of PET scanners.
- To provide a measurement technique that is independent of source attenuation and scatter.
- To enable accurate and reliable comparisons of absolute sensitivity across different PET scanners and configurations.
Main Methods:
- A new method was developed using a thin-line fluorine-18 source within an aluminum housing.
- Successive aluminum sleeves were added to the housing, and measurements were taken.
- Data were extrapolated to determine absolute sensitivity at zero aluminum thickness, yielding counts.s-1.MBq-1.
Main Results:
- Absolute sensitivities were measured as 3926 ± 61 counts.s-1.MBq-1 (0.39% efficiency) for a whole-body PET scanner with septa.
- Sensitivities of 5079 ± 26 counts.s-1.MBq-1 (0.51%) and 32312 ± 544 counts.s-1.MBq-1 (3.2%) were obtained for a NeuroPET with and without septa, respectively.
- The developed method provides absolute sensitivity measurements independent of attenuation and scatter.
Conclusions:
- The novel method successfully measures absolute PET scanner sensitivity in counts.s-1.MBq-1, independent of attenuation and scatter.
- This technique facilitates accurate comparisons of scanner performance across different devices and acquisition setups.
- The findings contribute to improved standardization and comparability in PET scanner characterization.