Presentation First Clinical Test of the Helmet-Chin PET Prototype

Tashima, Hideaki  ,  Yoshida, Eiji  ,  Iwao, Yuma  ,  Wakizaka, Hidekatsu  ,  Tazawa, Shusaku  ,  Seki, Chie  ,  Kimura, Yasuyuki  ,  Suhara, Tetsuya  ,  Yamaya, Taiga

Dementia is a severe problem in aging societies. There is a strong potential demand for high-sensitivity, high-resolution, and low-cost brain positron emission tomography (PET) imaging for its early diagnosis. Therefore, we have proposed the helmet-chin PET, a novel geometry for high-sensitivity brain imaging based on a hemispheric arrangement of detectors. For a proof-of-concept, we developed the first prototype using 4-layered depth-of-interaction (DOI) detectors. The helmet-chin PET prototype used 54 DOI detectors, each of which consisted of 16×16×4 Zr-doped GSO crystals (2.8×2.8×7.5 mm3) and a high sensitivity 64-channel flat-panel photomultiplier tube. In the prototype, 47 detectors were used to form a hemisphere of 25 cm inner diameter and 50 cm outer diameter, and 7 detectors were used for the chin detector. In this study, we conducted the first clinical test with a healthy volunteer. First, we compared sensitivity with a whole-body time-of-flight-PET (Biograph mCT Flow 64-4R PET/CT system, Siemens Medical Solutions USA, Inc.) to determine injection activity. As a result, the sensitivity of the helmet-chin PET prototype for the brain region was almost twice as high as that of the mCT, even though the number of detectors was less than 30% that of the mCT. Then a healthy volunteer was measured by the mCT for 15 min beginning 60 min after 18F-FDG injection of 70 MBq and by the helmet-chin PET for 18 min beginning 85 min after the injection. For the first clinical test, we could obtain a clear image of the brain with low radioactivity injection. We analyzed region of interest (ROI) values based on the anatomical structure. As a result, ROI values measured by the helmet-chin PET prototype and the mCT were in good agreement. The first clinical test showed promising performance of the helmet-chin PET for highly sensitive brain imaging.

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