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

Article type: Research Article

Authors: Ghani, Muhammad U.^a | Omoumi, Farid H.^a | Wu, Xizeng^b | Fajardo, Laurie L.^c | Zheng, Bin^a | Liu, Hong^{a; *}

Affiliations: [a] Advanced Medical Imaging Center and School of Electrical and Computer Engineering, University of Oklahoma, Norman, OK, USA | [b] Department of Radiology, University of Alabama at Birmingham, Birmingham, AL, USA | [c] Department of Radiology and Imaging Sciences, University of Utah, Salt Lake City, UT, USA

Correspondence: [*] Corresponding author: Hong Liu, Advanced Medical Imaging Center and School of Electrical and Computer Engineering, University of Oklahoma, Norman, OK 73019, USA. Tel.: +1 405 325 4286; E-mail: liu@ou.edu.

Abstract: 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 equal 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.

Keywords: Photon counting detector, phase contrast imaging, breast cancer detection, phase image retrieval, CdTe, ACR phantom

DOI: 10.3233/XST-211028

Journal: Journal of X-Ray Science and Technology, vol. 30, no. 2, pp. 207-219, 2022