Optimization of a customized simultaneous algebraic reconstruction technique algorithm for phase-contrast breast computed tomography

Abstract

Objective: To introduce the optimization of a customized GPU-based simultaneous algebraic reconstruction technique (cSART) in the field of phase-contrast breast computed tomography (bCT). The presented algorithm features a 3D bilateral regularization filter that can be tuned to yield optimal performance for clinical image visualization and tissues segmentation. Approach: Acquisitions of a dedicated test object and a breast specimen were performed at Elettra, the Italian synchrotron radiation (SR) facility (Trieste, Italy) using a large area CdTe single-photon counting detector. Tomographic images where obtained at 5 mGy of mean glandular dose, with a 32 keV monochromatic X-ray beam in the free-space propagation mode. Three independent algorithm’s parameters were optimized by using contrast-to-noise ratio (CNR), spatial resolution, and noise texture metrics. The results obtained with the cSART algorithm were compared with conventional SART and filtered back projection (FBP) reconstructions. Image segmentation was performed both with gray scale-based and supervised machine-learning approaches. Main results: Compared to conventional FBP reconstructions, results indicate that the proposed algorithm can yield images with a higher CNR (by 35% or more), retaining a high spatial resolution while preserving their textural properties. Alternatively, at the cost of an increased image “patchiness”, the cSART can be tuned to achieve a high-quality tissue segmentation, suggesting the possibility of performing an accurate glandularity estimation potentially of use in the realization of realistic 3D breast models starting from low radiation dose images. Significance: The study indicates that dedicated iterative reconstruction techniques could provide significant advantages in phase-contrast bCT imaging. The proposed algorithm offers great flexibility in terms of image reconstruction optimization, either towards diagnostic evaluation or towards image segmentation.

Characterization of breast tissues in density and effective atomic number basis via spectral X-ray computed tomography

“…A custom-made cylindrical phantom with a 10 cm diameter dedicated to calibration and quality control of the synchrotron breast CT system was used (Contillo et al 2018, Donato et al 2022. The phantom was filled with water and contained five inserts of polyethylene (PE), nylon (PA), PMMA, polyoxymethylene (POM), and polytetrafluoroethylene (PTFE) mimicking soft tissues of similar attenuation properties.…”

Improved Modeling of Temperature Evolution during Lung Cancer Tumor Thermal Ablation

“…Therefore, early specification and detection analyses using diagnostic process involving clinical exams, such as magnetic resonance imaging and ultrasound imaging, can guide efficient treatment and evacuation [8]. All effective strategies based on detection devices offer quantitative measurement and potential visualization for soft tissue at an n-dimension resolution without any risk of metathesis related to lung cancer.…”

Propagation-based phase-contrast breast computed tomography: a visual grading assessment of the performance of photon-counting and flat-panel X-ray detectors

“…PB-CT has not yet been validated as an alternative to MG and DBT for screening and diagnostic purposes, and scanning parameters and hardware necessary to produce the highest quality diagnostic images are still being investigated in preparation for the clinical trials that are foreseen in the next 1-2 years 22,23 . Previous research has determined the best imaging conditions for the breast PB-CT at synchrotron facilities (with phantoms, formalin-fixed specimens and fresh human tissues) in terms of X-ray energy, sample-to-detector distance and algorithms used for phase-retrieval and reconstruction 24, 25,26,27,27 .…”

“…High-Z sensors, such as CdTe, ensure a high absorption efficiency being suitable for applications where strict limitations in terms of dose are present. Moreover, thanks to the direct conversion mechanism of X-ray photons into electrical charge, these devices usually offer a pixel-size limited spatial resolution, whereas conventional detectors are usually limited by the blurring due to the conversion of deposited X-ray energy into visible light 28 . The latter feature is of great importance for PB-CT, as a high response sharpness ensures optimal detection of phase-contrast effects (i.e., edge-enhancement) 26,29,30 .…”