Recent Developments of Photon Counting and Energy Discriminating Detectors for Radiographic Imaging

Walter, D.; Zscherpel, Uwe; Ewert, Uwe

doi:10.1109/fendt.2017.8584559

Cited by 6 publications

(7 citation statements)

References 6 publications

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“…It takes advantage of differences between the mass absorption coefficient (energy penetration ability) of different materials. MDX provides information about the ratio between images acquired for two X-ray energy ranges [4,5].…”

Section: Materials Discrimination X-raymentioning

confidence: 99%

X-ray imaging of moving objects using on-chip TDI and MDX methods with single photon counting CdTe hybrid pixel detector

Żołądź¹,

Gryboś²,

Szczygieł³

2021

J. Inst.

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X-ray imaging of moving objects using line detectors remains the most popular method of object content and structure examination with a typical resolution limited to 0.4–1 mm. Higher resolutions are difficult to obtain as, for the detector in the form of a single pixel row, the narrower the detector is, the lower the image Signal to Noise Ratio (SNR). This is because, for smaller pixel sizes, fewer photons hit the pixel in each time unit for a given radiation intensity. To overcome the trade-off between the SNR and spatial resolution, a two-dimensional sensor, namely a pixel matrix can be used. Imaging of moving objects with a pixel matrix requires time-domain integration (TDI). Straightforward TDI implementation is based on the proper accumulation of images acquired during consecutive phases of an object’s movement. Unfortunately, this method is much more demanding regarding data transfer and processing. Data from the whole pixel matrix instead of a single pixel row must be transferred out of the chip and then processed. The alternative approach is on-chip TDI implementation. It takes advantage of photons acquired by multiple rows (a higher SNR), but generates similar data amount as a single pixel row and does not require data processing out of the chip. In this paper, on-chip TDI is described and verified by using a single photon counting two-dimensional (a matrix of 128 × 192 pixels) CdTe hybrid X-ray detector with the 100 µm × 100 µm pixel size with up to four energy thresholds per pixel. Spatial resolution verification is combined with the Material Discrimination X-ray (MDX) imaging method.

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Section: Materials Discrimination X-raymentioning

confidence: 99%

X-ray imaging of moving objects using on-chip TDI and MDX methods with single photon counting CdTe hybrid pixel detector

Żołądź¹,

Gryboś²,

Szczygieł³

2021

J. Inst.

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“…Additionally, the PCDs are equipped with a built-in charge sharing correction which compares charges being spread over nearest neighbor pixels within a single readout cycle and increases the counter only for the pixel with the highest individual charge [14]. The properties and parameter setting of this XCounter photon counting detectors are mentioned in detail by Walter et al [15,16].…”

Section: Photon Counting Detectorsmentioning

confidence: 99%

Dual-energy materials characterization methods for laminography image enhancement based on photon counting detector

Schumacher

Zscherpel

et al. 2019

J. Inst.

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A: Laminography is a widely used NDT technique for large flat object which cannot be investigated by traditional computed tomography. However, due to the limited scanning angle of laminography, the reconstructed image has more artifact interference, which seriously affects the reconstructed image quality. Reducing artifacts of the laminography image and enhancing the images have become important research effort. In this paper, we present dual-energy materials characterization methods based on photon counting detectors to reduce artifacts and enhance image for laminography. The photon counting detector used in this study allows the setting of two independent energy thresholds in order to acquire dual-energy images for laminography from a single scan. The dual energy imaging methods of basis material decomposition (BMD) and weighted logarithmic subtraction (WLS) were studied in the paper with respect to laminography image enhancement. A fast decomposition algorithm on laminographic projection domain with approximating the inverse dual-energy equations to calculate the thickness of basic materials was used in the BMD dual-energy imaging methods. The experimental results show that the BMD method can characterize materials and enhance features of the basic material within the laminographic dataset. In the WLS method, a linear operation was applied on dual-energy images reconstruction directly, which can eliminate the attenuation of one specific material in the resultant image by setting an appropriate weighting factor. In our experiments. WLS method was used successfully to eliminate the strong artifacts generated by the special material and enhance the images. Dual-energy materials characterization methods based on photon counting detectors show potential applications in laminography.

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“…PCDs offer new possibilities and improvements in computed tomography [11]. While many investigations about the benefits of PCDs in the medical field of CT have been reported over the past few years [12][13][14], the interest in the area of NDT is more recent [3,15,16]. For example, the expected clinical benefit in low-dose applications could be directly translated into industrial fast-CT applications.…”

Section: Photon Counting Detectorsmentioning

confidence: 99%

“…to equation ( 4)) for each detector (see equations ( 5) and ( 6)). The reconstructed SR b,reco is used to normalize the SNR and CNR measured in the reconstructed data sets according to equation (3).…”

Section: Gas Turbine Bladementioning

confidence: 99%

“…Additionally, beam hardening occurs due to the polychromatic source spectrum, which results in typical artefacts [2]. To address these problems, the use of photon counting detectors (PCD) with one or more energy thresholds is very promising [3]. PCDs allow to reduce the influence of scattered radiation and beam hardening by energy selective detection of the incident x-ray photons.…”

Section: Introductionmentioning

confidence: 99%

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Scatter and beam hardening reduction in industrial computed tomography using photon counting detectors

Schumacher

Sharma

Grager

et al. 2018

Meas. Sci. Technol.

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Photon counting detectors (PCD) offer new possibilities for x-ray micro computed tomography (CT) in the field of non-destructive testing. For large and/or dense objects with high atomic numbers the problem of scattered radiation and beam hardening severely influences the image quality. This work shows that using an energy discriminating PCD based on CdTe allows to address these problems by intrinsically reducing both the influence of scattering and beam hardening.Based on 2D-radiographic measurements it is shown that by energy thresholding the influence of scattered radiation can be reduced by up to 20% in case of a PCD compared to a conventional energy-integrating detector (EID).To demonstrate the capabilities of a PCD in reducing beam hardening, cupping artefacts are analyzed quantitatively. The PCD results show that the higher the energy threshold is set, the lower the cupping effect emerges. But since numerous beam hardening correction algorithms exist, the results of the PCD are compared to EID results corrected by common techniques. Nevertheless, the highest energy thresholds yield lower cupping artefacts than any of the applied correction algorithms.As an example of a potential industrial CT application, a turbine blade is investigated by CT. The inner structure of the turbine blade allows for comparing the image quality between PCD and EID in terms of absolute contrast, as well as normalized signal-to-noise and contrastto-noise ratio. Where the absolute contrast can be improved by raising the energy thresholds of the PCD, it is found that due to lower statistics the normalized contrast-to-noise-ratio could not be improved compared to the EID. These results might change to the contrary when discarding pre-filtering of the x-ray spectra and thus allowing more low-energy photons to reach the detectors.Despite still being in the early phase in technological progress, PCDs already allow to improve CT image quality compared to conventional detectors in terms of scatter and beam hardening reduction.

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Recent Developments of Photon Counting and Energy Discriminating Detectors for Radiographic Imaging

Cited by 6 publications

References 6 publications

X-ray imaging of moving objects using on-chip TDI and MDX methods with single photon counting CdTe hybrid pixel detector

X-ray imaging of moving objects using on-chip TDI and MDX methods with single photon counting CdTe hybrid pixel detector

Dual-energy materials characterization methods for laminography image enhancement based on photon counting detector

Scatter and beam hardening reduction in industrial computed tomography using photon counting detectors

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