Reduction of the Beam Hardening Artifacts in the X-Ray Computer Tomography: Energy Discrimination with a Photon-Counting Detector

Material decomposition in computed tomography is a method for differentiation and quantification of materials in a sample and it utilizes the energy dependence of the linear attenuation coefficient. In this study, a post-image reconstruction material decomposition method is constructed for a low-energy micro-CT setup using a photon counting x-ray detector. The low photon energy range (4–11 keV) allows for K-edge contrast separation of naturally occurring materials in organic tissue without the need of additional contrast agents. The decomposition method was verified using a phantom and its capability to decompose biomedical samples was evaluated with paraffin embedded human atherosclerotic plaques. Commonly, the necessary dual energy data for material decomposition is obtained by manipulating the emitted x-ray spectrum from the source. With the photon counting detector, this data was obtained by acquiring two energy window images on each side of the K-edge of one material in the sample. The samples were decomposed into three materials based on attenuation values in manually selected regions. The method shows a successful decomposition of the verification phantom and a distinct distribution of iron, calcium and paraffin in the atherosclerotic plaque samples. Though the decompositions are affected by beam hardening and ring artifacts, the method shows potential for spectral evaluation of biomedical samples.

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Novel material identification method using three energy bins of a photon counting detector taking into consideration Z-dependent beam hardening effect correction with the aim of producing an X-ray image with information of effective atomic number

2017 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC) ◽

10.1109/nssmic.2017.8533059 ◽

2017 ◽

Cited By ~ 2

Author(s):

N. Kimoto ◽

H. Hayashi ◽

T. Asahara ◽

E. Tomita ◽

S. Goto ◽

...

Keyword(s):

Atomic Number ◽

Photon Counting ◽

Effective Atomic Number ◽

Beam Hardening ◽

Material Identification ◽

X Ray ◽

Photon Counting Detector ◽

Identification Method ◽

Hardening Effect ◽

Novel Material

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The significance of the spectral correction of photon counting detector response in material classification from spectral x-ray CT

Quantum Optics and Photon Counting 2021 ◽

10.1117/12.2589290 ◽

2021 ◽

Author(s):

Doniyor Jumanazarov ◽

Ja-Keoung Koo ◽

Henning F. Poulsen ◽

Ulrik L. Olsen ◽

Mihai Iovea

Keyword(s):

Photon Counting ◽

Detector Response ◽

X Ray ◽

Photon Counting Detector ◽

Material Classification ◽

Spectral Correction

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Evaluation and comparison of a CdTe based photon counting detector with an energy integrating detector for X-ray phase sensitive imaging of breast cancer

Journal of X-Ray Science and Technology ◽

10.3233/xst-211028 ◽

2021 ◽

pp. 1-13

Author(s):

Muhammad U. Ghani ◽

Farid H. Omoumi ◽

Xizeng Wu ◽

Laurie L. Fajardo ◽

Bin Zheng ◽

...

Keyword(s):

Breast Cancer ◽

Spatial Resolution ◽

Standard Dose ◽

Photon Counting ◽

High Energy ◽

Edge Enhancement ◽

X Ray ◽

Photon Counting Detector ◽

Phase Sensitive ◽

Observer Studies

PURPOSE: To compare imaging performance of a cadmium telluride (CdTe) based photon counting detector (PCD) with a CMOS based energy integrating detector (EID) for potential phase sensitive imaging of breast cancer. METHODS: A high energy inline phase sensitive imaging prototype consisting of a microfocus X-ray source with geometric magnification of 2 was employed. The pixel pitch of the PCD was 55μm, while 50μm for EID. The spatial resolution was quantitatively and qualitatively assessed through modulation transfer function (MTF) and bar pattern images. The edge enhancement visibility was assessed by measuring edge enhancement index (EEI) using the acrylic edge acquired images. A contrast detail (CD) phantom was utilized to compare detectability of simulated tumors, while an American College of Radiology (ACR) accredited phantom for mammography was used to compare detection of simulated calcification clusters. A custom-built phantom was employed to compare detection of fibrous structures. The PCD images were acquired at equal, and 30% less mean glandular dose (MGD) levels as of EID images. Observer studies along with contrast to noise ratio (CNR) and signal to noise ratio (SNR) analyses were performed for comparison of two detection systems. RESULTS: MTF curves and bar pattern images revealed an improvement of about 40% in the cutoff resolution with the PCD. The excellent spatial resolution offered by PCD system complemented superior detection of the diffraction fringes at boundaries of the acrylic edge and resulted in an EEI value of 3.64 as compared to 1.44 produced with EID image. At MGD levels (standard dose), observer studies along with CNR and SNR analyses revealed a substantial improvement of PCD acquired images in detection of simulated tumors, calcification clusters, and fibrous structures. At 30% less MGD, PCD images preserved image quality to yield equivalent (slightly better) detection as compared to the standard dose EID images. CONCLUSION: CdTe-based PCDs are technically feasible to image breast abnormalities (low/high contrast structures) at low radiation dose levels using the high energy inline phase sensitive imaging technique.

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