[Influence of count rate on image quality in three-dimensional PET acquisition].
OBJECTIVE
In FDG-PET examinations, optimization of the injected dose and duration of acquisition are important in determining the physical performance of PET or the PET/CT scanner. This study was intended to elucidate the influence of count rate on image quality.


METHODS
Three PET/CT scanners (Biograph sensation 16, Discovery ST, and Aquiduo) were used in this study. Body and scatter phantoms (NEMA 2001) and a cylindrical phantom (for QC use) were also used. Data acquisition was performed repeatedly for about 6 h to achieve a fixed 15 million counts of true plus scatter. The count rate performance and image quality (signal-to-noise ratio and contrast) of each frame were analyzed after data acquisition. The relationship between the count rate and image quality was also analyzed.


RESULTS
A positive correlation between the random fraction (ratio of random to prompt count rate) and signal-to-noise ratio was found in all PET/CT scanners, but with differing effects of the count rate's influence on image quality. Image contrast was not correlated with count rate.


CONCLUSIONS
Acquisition parameters must be determined by considering each scanner's effect on how count rate influences image quality.
Daisaki
Hiromitsu
H
Cancer Screening Division, National Cancer Center Research Center for Cancer Prevention and Screening.
Suzuki
Kazufumi
K
Fukukita
Hiroyoshi
H
Fukushima
Hitoshi
H
Satou
Takashi
T
Shinohara
Hiroyuki
H
D005462:Fluorine Radioisotopes; D019788:Fluorodeoxyglucose F18; D021621:Imaging, Three-Dimensional / Q000295:instrumentation / Q000379:methods*; D019047:Phantoms, Imaging; D049268:Positron-Emission Tomography / Q000295:instrumentation / Q000379:methods*; D019275:Radiopharmaceuticals
D005462:Fluorine Radioisotopes; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18