HEXITEC 2 × 2 tiled hard X-ray spectroscopic imaging detector system

Abstract

HEXITEC is a spectroscopic imaging X-ray detector technology developed at the STFC Rutherford Appleton Laboratory for X-ray and γ-ray spectroscopic imaging applications. Each module has 80 × 80 pixels on a 250 μm pixel pitch, and has been implemented successfully in a number of applications. This paper presents the HEXITEC 2 × 2 detector system, a tiled array of 4 HEXITEC modules read out simultaneously, which provides an active area of 16 cm2. Systems have been produced using 1 mm thick Cadmium Telluride (CdTe) and 2 mm thick Cadmium Zinc Telluride (CdZnTe) sensor material. In this paper the system and data processing methods are presented, and the performance of the systems are evaluated. The detectors were energy calibrated using an 241Am sealed source. Three types of charge sharing correction were applied to the data-charge sharing addition (CSA), charge sharing discrimination (CSD), and energy curve correction (ECC) which compensates for energy lost in the inter-pixel region. ECC recovers an additional 34 % of counts in the 59.5 keV peak in CdTe compared to the use of CSD; an important improvement for photon-starved applications. Due to the high frame rate of the camera system (6.3 kHz) an additional End of Frame (EOF) correction was also applied to 6.0 % of events to correct for signals that were readout whilst the signal was still forming. After correction, both detector materials were found to have excellent spectroscopic performance with a mean energy resolution (FWHM) of 1.17 keV and 1.16 keV for CdZnTe and CdTe respectively. These results successfully demonstrate the ability to construct tiled arrays of HEXITEC modules to provide larger imaging areas.

Use of the Fully Spectroscopic Pixelated Cadmium Telluride Detector for Benchtop X-Ray Fluorescence Computed Tomography

“…If a horizontal detector translation was not necessary, the total XFCT imaging dose from the current work would become ~53 and ~107 cGy for 5 and 10 s acquisition time, respectively. Note, while it could not be achievable during the current work, this scenario (i.e., no horizontal detector translation) is readily achievable with a newer version of HEXITEC [ 26 ] providing a larger FOV or XFCT scanning of smaller objects that can be within the current FOV of HEXITEC.…”

First Study of a HEXITEC Detector for Secondary Particle Characterisation during Proton Beam Therapy

“…The low flux reported in the detector area is a result of the dimensions of the detector under study. Fortunately, these values may be enhanced, as recent HEXITEC developments incude bigger detector areas and higher frame rates [27,35]. The amount of gammas with the potential to be detected outside of the patient's body have been reported to be low, especially for gammas that are classified as prompt.…”

“…Although originally designed for material science X-ray imaging at energies up to 200 keV, this system has been used for several applications. In particular, its uses in medical physics include spectroscopic X-ray imaging [26,27], SPECT imaging for the brain [28] and targeted alpha therapy [29], but this is the first application of the HEXITEC detector in a proton beam therapy scenario.…”

Synthetic β-sheets mimicking fibrillar and oligomeric structures for evaluation of spectral X-ray scattering technique for biomarker quantification

“…The wavevector, is calculated for each scattering angle (2θ) and energy using the equation: where, hc = 1.24 eV-µm. The charge sharing discrimination (CSD) was applied for charge sharing correction [ 76 ]. A beamstop with a 300 µm hole was placed in front of the detector to reduce the spectral degradation from pulse pile-up.…”