The Dosepix detector—an energy-resolving photon-counting pixel detector for spectrometric measurements

Abstract

The Dosepix detector is a hybrid photon-counting pixel detector based on ideas of the Medipix and Timepix detector family. 1 mm thick cadmium telluride and 300 µm thick silicon were used as sensor material. The pixel matrix of the Dosepix consists of 16 x 16 square pixels with 12 rows of (200 µm) 2 and 4 rows of (55 µm) 2 sensitive area for the silicon sensor layer and 16 rows of pixels with 220 µm pixel pitch for CdTe. Besides digital energy integration and photoncounting mode, a novel concept of energy binning is included in the pixel electronics, allowing energy-resolved measurements in 16 energy bins within one acquisition.The possibilities of this detector concept range from applications in personal dosimetry and energy-resolved imaging to quality assurance of medical X-ray sources by analysis of the emitted

Personal Dosimetry in Direct Pulsed Photon Fields with the Dosepix Detector

“…The results are shown in Figure 3 for each pixel size of the three detectors and are additionally labeled by their filter cap, i.e., aluminum cylinder with a thin aluminum foil on its top, which has a hole above the sensor (free), aluminum half-sphere (Al), and tin half-sphere (Sn). Similar behavior is observed as presented by Zang et al [13], which means that the count rate saturates with high dose rates for unfiltered or weakly filtered detectors. The Dosepix filtered with tin shows for both pixel types no saturation and overall a low count rate.…”

“…A single column is read out at a time while the rest of the matrix continues to process signals, which is a significant advantage in practical applications in pulsed photon fields, where radiation pulses are random in time. Information regarding the characterizations of Dosepix with X-rays and analog test-pulses can be found in [12], and measurements of the count rate linearity in dependence of the dose rate can be found in [13]. A dosimetry system consisting of 3 Dosepix detectors is utilized as described in [11], where the energy and angular dependence in continuous photon fields were already presented.…”

“…The measurements with the RQR8 spectrum when varying the dose rate are compared to previous measurements performed in [13]. For comparability, the abscissa is first re-scaled to Sv/s and then divided by the Hp(10)/Kair conversion coefficient for the RQR8 spectrum (1.438 Sv/Gy).…”

Personal Dosimetry in Direct Pulsed Photon Fields With the Dosepix Detector

“…Information regarding the characterizations of Dosepix with X-rays and analog test-pulses can be found in [15], and measurements of the count rate linearity in dependence of the dose rate can be found in [16]. A dosimetry system consisting of 3 Dosepix detectors is utilized as described in [17], where the energy and angular dependence in continuous photon fields were already presented.…”

“…The measurements with the RQR8 spectrum when varying the dose rate are compared to previous measurements performed in [16]. For comparability, the abscissa is first rescaled to Sv/s and then divided by the H p (10)/K air conversion coefficient for the RQR8 spectrum (1.438 Sv/Gy).…”