Digital X-ray portable scanner based on monolithic semi-insulating GaAs detectors: General description and first “quantum” images

• Published in: Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment Accelerators, spectrometers, detectors and associated equipment, 2005-07, Vol.546 (1), p.118-124
• Main Authors: Dubecký, F., Perd’ochová, A., Ščepko, P., Zat’ko, B., Sekerka, V., Nečas, V., Sekáčová, M., Hudec, M., Boháček, P., Huran, J.
• Format: Article
• Language: English
• Subjects: Digital imaging; Digital X-ray scanner; SI GaAs strip line detector; X-ray irradiation
• ISSN: 0168-9002; 1872-9576
• DOI: 10.1016/j.nima.2005.03.020

The present work describes a portable digital X-ray scanner based on bulk undoped semi-insulating (SI) GaAs monolithic strip line detectors. The scanner operates in “quantum” imaging mode (“single photon counting”), with potential improvement of the dynamic range in contrast of the observed X-ray images. The “heart” of the scanner (detection unit) is based on SI GaAs strip line detectors. The measured detection efficiency of the SI GaAs detector reached a value of over 60 % (compared to the theoretical one of ∼75 %) for the detection of 60 keV photons at a reverse bias of 200 V. The read-out electronics consists of 20 modules fabricated using a progressive SMD technology with automatic assembly of electronic devices. Signals from counters included in the digital parts of the modules are collected in a PC via a USB port and evaluated by custom developed software allowing X-ray image reconstruction. The collected data were used for the creation of the first X-ray “quantum” images of various test objects using the imaging software developed.