K-edge subtraction imaging using a pixellated energy-resolving detector

Purpose: Contrast-enhanced imaging of the breast is frequently used in breast MRI and has recently become more common in mammography. The purpose of this study was to make single-scan contrast-enhanced imaging feasible for photon-counting breast CT (pcBCT) and to assess the spectral performance of a pcBCT scanner by evaluating iodine maps and virtual non-contrast (VNC) images. Methods: We optimized the settings of a pcBCT to maximize the signal-to-noise ratio between iodinated contrast agent and breast tissue. Therefore, an electronic energy threshold dividing the x-ray spectrum used into two energy bins was swept from 23.17 keV to 50.65 keV. Validation measurements were performed by placing syringes with contrast agent (2.5 mg/ml to 40 mg/ml) in phantoms with 7.5 cm and 12 cm in diameter. Images were acquired at different tube currents and reconstructed with 300 lm isotropic voxel size. Iodine maps and VNC images were generated using image-based material decomposition. Iodine concentrations and CT values were measured for each syringe and compared to the known concentrations and reference CT values. Results: Maximal signal-to-noise ratios were found at a threshold position of 32.59 keV. Accurate iodine quantification (average root mean square error of 0.56 mg/ml) was possible down to a concentration of 2.5 mg/ml for all tube currents investigated. The enhancement has been sufficiently removed in the VNC images, so they can be interpreted as unenhanced CT images. Only minor changes of CT values compared to a conventional CT scan were observed. Noise was increased by the decomposition by a factor of 2.62 and 4.87 (7.5 cm and 12 cm phantoms) but did not compromise the accuracy of the iodine quantification. Conclusions: Accurate iodine quantification and generation of VNC images can be achieved using contrast-enhanced pcBCT from a single CT scan in the absence of temporal or spatial misalignment. Using iodine maps and VNC images, pcBCT has the potential to reduce dose, shorten examination and reading time, and to increase cancer detection rates.

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“…A wide energy bin will lead to low noise, but low contrast. A narrow energy bin will lead to high contrast, but increased noise 46 …”

Section: Methodsmentioning

confidence: 99%

“…A narrow energy bin will lead to high contrast, but increased noise. 46 The values from the projection data can be interpreted approximately as linear attenuation coefficients l as outlined in [Eq. ( 1)].…”

Section: C Energy Threshold Calibrationmentioning

confidence: 99%

Investigation of spectral performance for single‐scan contrast‐enhanced breast CT using photon‐counting technology: A phantom study

Ruth

Kolditz²,

Steiding³

et al. 2020

Medical Physics

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“…There are also potential applications in neurology, where simultaneous imaging of brain perfusion (Tc-99m) and dopamine transporters (I-123) can help to differentiate Parkinson’s disease from Multiple System Atrophy. In this application, both high spatial- and energy resolution is required, and The Royal Surrey County Hospital is developing a solid-state detector system for this purpose as part of the HEXITEC collaboration. K-Edge Absorption Imaging by Scanning and Cone Beam Projection: We have done initial trials for use as identification of cancerous tissue samples with Iodine as a K-edge absorbing contrast agent at 33 keV [34]. …”

Section: Applicationsmentioning

confidence: 99%

Pixellated Cd(Zn)Te high-energy X-ray instrument

et al. 2011

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We have developed a pixellated high energy X-ray detector instrument to be used in a variety of imaging applications. The instrument consists of either a Cadmium Zinc Telluride or Cadmium Telluride (Cd(Zn)Te) detector bump-bonded to a large area ASIC and packaged with a high performance data acquisition system. The 80 by 80 pixels each of 250 μm by 250 μm give better than 1 keV FWHM energy resolution at 59.5 keV and 1.5 keV FWHM at 141 keV, at the same time providing a high speed imaging performance. This system uses a relatively simple wire-bonded interconnection scheme but this is being upgraded to allow multiple modules to be used with very small dead space. The readout system and the novel interconnect technology is described and how the system is performing in several target applications.

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“…The detector is actively being used in multi-isotope SPECT imaging [4], K-edge imaging [5], illicit material detection [6], and in materials science applications [7]. Many of these applications require large detector areas but without sacrificing the spectroscopic, or spatial, resolution of the detector.…”

mentioning

confidence: 99%

Characterization of Edgeless CdTe Detectors for use in Hard X-Ray Imaging Applications

Veale

Bell

Jones

et al. 2012

IEEE Trans. Nucl. Sci.

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Segmentation of the anode-side of a CdTe diode produces detectors with excellent spatial and energy resolution while maintaining an active area that extends to the detector edge. The CdTe pixel detectors reported have 250 ìm pitch, a detector thicknesses of 1 mm and are bonded to a spectroscopic readout ASIC. The results from an edgeless CdTe detector with indium-diffused anodes, produced via diamond blade segmentation, are compared to those of a CdTe Schottky pixel detector with aluminium anodes and guard band produced using standard photolithographic techniques. The energy resolution at 59.54 keV was measured to be 1.4% and 1.3% for the standard and edgeless detector respectively. The spectroscopic performance of pixels located at the detector edges are discussed with reference to TCAD simulations and X-ray micro-beam measurements.

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K-edge subtraction imaging using a pixellated energy-resolving detector

Cited by 15 publications

References 7 publications

Investigation of spectral performance for single‐scan contrast‐enhanced breast CT using photon‐counting technology: A phantom study

Investigation of spectral performance for single‐scan contrast‐enhanced breast CT using photon‐counting technology: A phantom study

Pixellated Cd(Zn)Te high-energy X-ray instrument

Characterization of Edgeless CdTe Detectors for use in Hard X-Ray Imaging Applications

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