Attenuation correction for phantom tests: an alternative to maximum-likelihood attenuation correction factor-based correction for clinical studies in time-of-flight PET.

Autor: Mizuta, Tetsuro, Yamakawa, Yoshiyuki, Minagawa, Suzuka, Kobayashi, Tetsuya, Ohtani, Atsushi, Takenouchi, Shiho, Hanaoka, Kohei, Watanabe, Shota, Morimoto-Ishikawa, Daisuke, Yamada, Takahiro, Kaida, Hayato, Ishii, Kazunari
Zdroj: Annals of Nuclear Medicine; Nov2022, Vol. 36 Issue 11, p998-1006, 9p
Abstrakt: Objectives: This study evaluates the phantom attenuation correction (PAC) method as an alternative to maximum-likelihood attenuation correction factor (ML-ACF) correction in time-of-flight (TOF) brain positron emission tomography (PET) studies. Methods: In the PAC algorithm, a template emission image λ Ref and a template attenuation coefficient image μ Ref are prepared as a data set based on phantom geometry. Position-aligned attenuation coefficient image μ Acq is derived by aligning μ Ref using parameters that match the template emission image λ Ref to measured emission image λ Acq . Then, attenuation coefficient image μ Acq combined with a headrest image is used for scatter and attenuation correction in the image reconstruction. To evaluate the PAC algorithm as an alternative to ML-ACF, Hoffman 3D brain and cylindrical phantoms were measured to obtain the image quality indexes of contrast and uniformity. These phantoms were also wrapped with a radioactive sheet to obtain attenuation coefficient images using ML-ACF. Emission images were reconstructed with attenuation correction by PAC and ML-ACF, and the results were compared using contrast and uniformity as well as visual assessment. CT attenuation correction (CT-AC) was also applied as a reference. Results: The contrast obtained by ML-ACF was slightly overestimated due to its unique experimental condition for applying ML-ACF in Hoffman 3D brain phantom but the uniformity was almost equivalent among ML-ACF, CT-AC, and PAC. PAC showed reasonable result without overestimation compared to ML-ACF and CT-AC. Conclusions: PAC is an attenuation correction method that can ensure the performance in phantom test, and is considered to be a reasonable alternative to clinically used ML-ACF-based attenuation correction. [ABSTRACT FROM AUTHOR]
Databáze: Complementary Index
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