Implementation and CT sampling characterization of a third-generation SPECT–CT system for dedicated breast imaging

Abstract

Stand-alone cone beam computed tomography (CT) and single-photon emission computed tomography (SPECT) systems capable of complex acquisition trajectories have previously been developed for breast imaging. Fully three-dimensional (3-D) motions of SPECT systems provide views into the chest wall and throughout the entire volume. The polar tilting capability of the CBCT system has shown improvement in sampling close to the chest wall, while eliminating cone beam artifacts. Here, a single hybrid SPECT-CT system, with each individual modality capable of independently traversing complex trajectories around a common pendant breast volume, was developed. We present the practical implementation of this design and preliminary results of the CT system. The fully 3-D SPECT was nested inside the suspended CT gantry and oriented perpendicular to the CT source-detector pair. Both subsystems were positioned on a rotation stage, with the combined polar and azimuthal motions enabling spherical trajectories. Six trajectories were used for initial evaluation of the tilt capable CT system. The developed system can achieve polar tilt angles with a [Formula: see text] positioning error and no hysteresis. Initial imaging results demonstrate that additional off-axis projection views of various geometric resolution phantoms facilitate more complete sampling, more consistent attenuation value recovery, and markedly improved reconstructions. This system could have various applications in diagnostic or therapeutic breast imaging.

Characterization of CT Hounsfield Units for 3D acquisition trajectories on a dedicated breast CT system

“…Modulation transfer function (MTF) and sampling studies [7] were performed in the past using tilted trajectories in addition to x-ray scatter [25] and dose distribution [9] studies. We have recently also developed a tilt capable, hybrid SPECT-CT system where each modality is independently capable of traversing 3D orbits [28]. However, a comprehensive characterization of HU values for these systems having capability of different 3D trajectories, and comparison with standard metrics has never been performed for titled 3D trajectories.…”

“…However, these studies did not consider the effect of different acquisition orbits on linear attenuation coefficients. For tilted trajectories, as the polar tilt angle of the system changes, the angle of incidence of the x-ray beam changes, thereby changing the path lengths of the x-rays incident on the target volume [28, 30]. This results in differences in the dose distribution [9], and scatter distribution [10], which in turn would affect the reconstructed absolute attenuation coefficients and thereby the HU values.…”

An Exploratory Multi-reader, Multi-case Study Comparing Transmission Ultrasound to Mammography on Recall Rates and Detection Rates for Breast Cancer Lesions

“…Dedicated breast CT has been studied over the past few years (19). Additionally, other CT based multimodality based systems (SPECT-CT and PET-CT) have also been developed, however, the use of these systems in the clinic remains limited, given the potential radiation safety issues for screening in younger women (20,21).…”

Detection of Microcalcifications in Spiral Breast Computed Tomography with Photon-Counting Detector Is Feasible: A Specimen Study

“…Lindfors et al developed a cone-beam breast-CT, in which visualization of masses was significantly better compared to mammography, but visualization of MCs was significantly worse [ 14 ]. Shah et al constructed a tilt-capable combination of SPECT and cone beam-CT to gain a better sampling of breast tissue close to the chest wall [ 15 ]. Evaluation of a commercially available cone-beam breast-CT showed that detection of malignant lesions, including DCIS, was superior compared to mammography, but results regarding the detection of MCs are lacking [ 16 ].…”