Development of heavy-element semiconductor radiation detectors for realizing ultra-high resolution SPECT

2021 Fiscal Year Final Research Report

• Project/Area Number: 20K20211
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 90130:Medical systems-related
• Research Institution: Tohoku University
• Principal Investigator: Mitsuhiro Nogami 東北大学, 工学研究科, 助手 (10847304)
• Project Period (FY): 2020-04-01 – 2022-03-31
• Keywords: 放射線計測 / SPECT / 重元素半導体検出器 / 臭化タリウム(TlBr) / 超高分解能サブミリSPECT

Outline of Final Research Achievements

SPECT (single-photon emission computed tomography) is used as a tool in diagnosing the physiological functions of organs. A drawback of SPECT is the low spatial resolutions about 1 cm. Radiation detectors used for SPECT are required for high spatial resolutions to find small lesions. In this study, a signal processing technology was developed to improve the spatial resolutions of TlBr pixelated semiconductor radiation detectors with an anode pixel electrode, a guard electrode, and a cathode electrode. The radial interaction position in the anode pixel for the incident gamma ray was determined by taking the anode to guard electrode signal ratio. In addition, the depth of interaction of the incident gamma ray was determined by taking the cathode to anode signal ratio. The energy resolution of the TlBr pixelated detector was improved by selecting the events occurred near the cathode surface region and in the central region of the anode pixel.

Free Research Field

放射線計測学

Academic Significance and Societal Importance of the Research Achievements

SPECTは臓器の機能検査に用いられる装置であり、比較的半減期の長い放射性薬剤を用いるため、大型施設が不要である。しかしながら、空間分解能が1 cm程度と低いことが最大の欠点となっている。SPECTの空間分解能を向上させるためには、高い固有分解能を有するガンマ線検出器が必須である。本研究では、ガンマ線を高効率に計測可能なTlBrピクセル半導体検出器において、各電極からの信号の波高値比を用いることにより固有分解能が向上することを実証した。本研究の成果は、SPECTの空間分解能の改善につながるものである。