WEKO3
アイテム
Toward Whole Gamma Imaging of 89Zr: a Demonstration of Combined PET and Compton Imaging
https://repo.qst.go.jp/records/76761
https://repo.qst.go.jp/records/767616f14e4d5-2e6c-45f2-8a43-8aea1ce572ce
| Item type | 会議発表用資料 / Presentation(1) | |||||
|---|---|---|---|---|---|---|
| 公開日 | 2019-08-23 | |||||
| タイトル | ||||||
| タイトル | Toward Whole Gamma Imaging of 89Zr: a Demonstration of Combined PET and Compton Imaging | |||||
| 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 |
Tashima, Hideaki
× Tashima, Hideaki× Yoshida, Eiji× Wakizaka, Hidekatsu× Takahashi, Miwako× Nagatsu, Kotaro× Tsuji, Atsushi× Kamada, Kei× Parodi, Katia× Yamaya, Taiga× Tashima, Hideaki× Yoshida, Eiji× Wakizaka, Hidekatsu× Takahashi, Miwako× Nagatsu, Kotaro× Tsuji, Atsushi× Parodi, Katia× Yamaya, Taiga |
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| 抄録 | ||||||
| 内容記述タイプ | Abstract | |||||
| 内容記述 | Background and purpose We proposed the whole gamma imaging (WGI) concept, which is a novel combination of PET and Compton camera (Compton imaging) technologies by inserting a scatterer ring into a PET ring. The PET ring works as an absorber detector in Compton imaging. In order to show a proof of the WGI concept that all detected radiation signals should be used for 3D tomographic imaging, in this study, we targeted 89Zr, which is useful for its long half-life. 89Zr emits 909 keV gamma rays as well as positrons. 89Zr can be imaged by PET, but the ratio of positron decay is only 23%, while a 909 keV gamma ray is emitted almost 100% with some time interval. We expect that the WGI can measure 511-keV photons from positrons as PET events and 909-keV gamma rays as Compton events. Therefore, we can use both events for 89Zr image reconstruction to improve image quality. In this study, we demonstrated hybrid image reconstruction of PET and Compton events measured by a WGI proof-of-concept prototype developed for small animal study. Methods We developed a hybrid image reconstruction algorithm utilizing both PET and Compton events. The algorithm was based on the list-mode ordered subset expectation maximization (OSEM) algorithm. For each image update, the update vector was calculated as the weighted sum of updated vectors for PET and Compton events. For the demonstration, we measured a mouse with the WGI prototype, 22 hours after the injection of 89Zr-oxalate of 9.8 MBq, which assimilates in the bone. Because the prototype was developed with singles-based data acquisition system, coincidence events of 511-keV photons and 909 keV gamma rays were extracted after the measurement. The PET events were extracted as coincidence events with the energy window of 350-650 keV for the scatterer ring only. The Compton events were extracted as coincidence events between the scatterer ring and the absorber ring with the energy windows of 50-350 keV and 550-850 keV, respectively. We reconstructed short time frame images using only PET events (PET mode), using only Compton events (Compton imaging mode), and using both events (WGI mode). Results The PET mode was noisy because the number of counts acquired for the short frame were small. On the other hand, the number of Compton events was 8 times larger than PET events. Although the spatial resolution was inferior, the Compton imaging mode was less noisy and the field of view (FOV) was wider than the PET mode. In addition, the WGI mode showed comparable spatial resolution to the PET mode within the scatterer ring area and less noise than the Compton imaging mode. Conclusion We developed a hybrid image reconstruction algorithm combining list-mode data for PET events and Compton events to improve the image quality realizing the WGI concept. The demonstration with 89Zr mouse measured by the WGI prototype showed that the developed algorithm for the WGI mode could reduce image noise compared with PET mode while maintaining the spatial resolution. |
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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 | World Molecular Imaging Congress 2019 | |||||
| 発表年月日 | ||||||
| 日付 | 2019-09-06 | |||||
| 日付タイプ | Issued | |||||
