[19p-D61-1~18] 2.1 検出器デバイス開発

16:15 〜 16:30英語発表

[19p-D61-13] Direct Conversion Flat Panel Detectors Using 25 µm Thick TlBr Film for X-ray Imaging

〇Moh Hamdan¹, Donghwan Kim¹, Kenji Shimazoe¹, Hiroyuki Takahashi¹, Mitsuhiro Nogami², Keitaro Hitomi², Shinya Asakura³, Takanori Tsunashima³, Takashi Nakamura³ (1.The University of Tokyo, 2.Tohoku University, 3.Japan Display Inc.)

キーワード：

Flat Panel Detector、TlBr Film、X-ray Imaging

Direct conversion Flat Panel Detectors (FPDs) have garnered significant attention for X-ray imaging in both medical and industrial fields due to their enhanced image quality. The choice of conversion materials, which directly convert X-rays into electrical charges, is crucial for the performance of these detectors. Thallium Bromide (TlBr) is an attractive material owing to its suitable energy bandgap (2.68 eV), high atomic numbers (Z_Tl = 81, Z_Br = 35), and high density (7.56 g/cm³). This study aims to develop and characterize a direct conversion FPD using a 25 µm thick TlBr film. The TlBr film, with a thickness of 25 µm and a sensitive area of 29.61 × 39.48 mm², was deposited using the evaporation method. A pixelated sensor matrix, featuring 168 × 126 pixels with a pixel size of 235 × 235 µm², was developed using Low-Temperature Polysilicon Thin-Film Transistor (LTPS TFT) technology. Spatial resolution was evaluated using the slanted edge method with the TlBr layer biased at 1.00 V, capturing 100 frames for each experiment. For imaging performance assessment, an anchovy object was imaged with a TlBr bias voltage of 0.75 V, capturing 1000 frames. The X-ray tube was operated at a voltage range of 23.0 kV to 100.0 kV with a current range of 0.25 mA to 2.00 mA. The spatial resolution, determined from the Line Spread Function (LSF) profile, ranged from 222 to 280 µm Full Width at Half Maximum (FWHM), constrained by the pixel size. The imaging demonstration of the anchovy object clearly discerned its shape and structure, indicating effective image capture by the TlBr FPD. The results show that the TlBr FPD achieves reasonable spatial resolution and detailed imaging, showcasing its potential for practical applications in X-ray imaging.