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Helmet-type brain TOF-PET prototype: improved timing resolution and count rate performance by optimizing energy window
https://repo.qst.go.jp/records/80243
https://repo.qst.go.jp/records/802431276238a-1f27-4982-be24-df844b2e7b91
| Item type | 会議発表用資料 / Presentation(1) | |||||
|---|---|---|---|---|---|---|
| 公開日 | 2020-07-28 | |||||
| タイトル | ||||||
| タイトル | Helmet-type brain TOF-PET prototype: improved timing resolution and count rate performance by optimizing energy window | |||||
| 言語 | ||||||
| 言語 | eng | |||||
| 資源タイプ | ||||||
| 資源タイプ識別子 | http://purl.org/coar/resource_type/c_c94f | |||||
| 資源タイプ | conference object | |||||
| アクセス権 | ||||||
| アクセス権 | metadata only access | |||||
| アクセス権URI | http://purl.org/coar/access_right/c_14cb | |||||
| 著者 |
Akamatsu, Go
× Akamatsu, Go× Yoshida, Eiji× Tashima, Hideaki× Iwao, Yuma× Wakizaka, Hidekatsu× Maeda, Takamasa× Takahashi, Miwako× yamashita, taichi× Yamaya, Taiga× Akamatsu, Go× Yoshida, Eiji× Tashima, Hideaki× Iwao, Yuma× Wakizaka, Hidekatsu× Maeda, Takamasa× Takahashi, Miwako× Yamashita, Taichi× Yamaya, Taiga |
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| 抄録 | ||||||
| 内容記述タイプ | Abstract | |||||
| 内容記述 | Objectives: Brain PET is a powerful imaging tool to visualize various functions and metabolism of the human brain. To make a high-sensitivity brain PET system with a limited number of detectors, we have proposed a hemispherical detector arrangement. In addition, we have developed a prototype system with a time-of-flight (TOF) measurement capability. To maximize the effective sensitivity of the prototype system, the energy window should be optimized in consideration of coincidence count detection sensitivity, timing resolution, and scatter fraction. In this work, we investigated optimal energy window of the helmet-type TOF-PET prototype so as to obtain better count rate performance. Methods: The helmet-type TOF-PET prototype consisted of 54 block detectors. The 45 detectors were arranged to form a hemisphere and the other 9 detectors were placed to form a half-ring behind the neck. The detector block was composed of 10-mm-thick lutetium fine silicate (LFS) scintillators and silicon photomultiplier (SiPM) with one-to-one coupling. The scintillator thickness was optimized through simulation so as to reduce the parallax error while maintaining the TOF gain in image quality. The system average energy resolution was 12.6% at 511 keV. First, we set a wide energy window of 400–700 keV. After singles data acquisition, 12 patterns of additional energy window were applied. We used the lower energy window of 400, 420 and 440 keV and the upper energy window of 570, 590, 620 and 700 keV. The timing resolution was measured with singles data of a 22Na point source at the center of the bottom detector ring. The count rate performance was measured using the brain-size (20-cm diameter and 17.5-cm length) cylindrical scatter phantom* and the scatter fraction was measured according to the procedure of the NEMA NU2 standards publication. Based on these data, we calculated a noise-equivalent count rate (NECR) with TOF sensitivity gain for each energy window. Finally, the image quality was evaluated with the brain-size image quality phantom*. Results: In all energy window settings, the system timing resolutions were 235.9–245.6 ps, the scatter fractions were 23.2–36.1% and the NECRs with the TOF gain at the 20 MBq were 117.5–128.9 kcps/MBq. The scatter fraction considerably depended on the lower energy window setting. Using the energy window of 440–590 keV, the highest NECR with TOF gain was achieved with the 236.1-ps timing resolution. For the image quality assessment, the higher contrast and lower noise were obtained with the energy window of 440–590 keV. Conclusions: We investigated optimal energy window for the helmet-type TOF-PET prototype. On the current setup, the highest count rate performance and better image quality were obtained with the energy window of 440–590 keV. Also, the timing resolution was improved to be 236.1 ps. [*: Akamatsu G, et al. Biomed Phys Eng Express. 2020;6:015012] |
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| 会議概要（会議名, 開催地, 会期, 主催者等） | ||||||
| 内容記述タイプ | Other | |||||
| 内容記述 | SNMMI 2020 Annual Meeting | |||||
| 発表年月日 | ||||||
| 日付 | 2020-07-11 | |||||
| 日付タイプ | Issued | |||||
