Flat panel detector‐based cone beam computed tomography with a circle‐plus‐two‐arcs data acquisition orbit: Preliminary phantom study

Abstract

Cone beam computed tomography (CBCT) has been investigated in the past two decades due to its potential advantages over a fan beam CT. These advantages include (a) great improvement in data acquisition efficiency, spatial resolution, and spatial resolution uniformity, (b) substantially better utilization of x-ray photons generated by the x-ray tube compared to a fan beam CT, and (c) significant advancement in clinical three-dimensional (3D) CT applications. However, most studies of CBCT in the past are focused on cone beam data acquisition theories and reconstruction algorithms. The recent development of x-ray flat panel detectors (FPD) has made CBCT imaging feasible and practical. This paper reports a newly built flat panel detector-based CBCT prototype scanner and presents the results of the preliminary evaluation of the prototype through a phantom study. The prototype consisted of an x-ray tube, a flat panel detector, a GE 8800 CT gantry, a patient table and a computer system. The prototype was constructed by modifying a GE 8800 CT gantry such that both a single-circle cone beam acquisition orbit and a circle-plus-two-arcs orbit can be achieved. With a circle-plus-two-arcs orbit, a complete set of cone beam projection data can be obtained, consisting of a set of circle projections and a set of arc projections. Using the prototype scanner, the set of circle projections were acquired by rotating the x-ray tube and the FPD together on the gantry, and the set of arc projections were obtained by tilting the gantry while the x-ray tube and detector were at the 12 and 6 o'clock positions, respectively. A filtered backprojection exact cone beam reconstruction algorithm based on a circle-plus-two-arcs orbit was used for cone beam reconstruction from both the circle and arc projections. The system was first characterized in terms of the linearity and dynamic range of the detector. Then the uniformity, spatial resolution and low contrast resolution were assessed using different phantoms mainly in the central plane of the cone beam reconstruction. Finally, the reconstruction accuracy of using the circle-plus-two-arcs orbit and its related filtered backprojection cone beam volume CT reconstruction algorithm was evaluated with a specially designed disk phantom. The results obtained using the new cone beam acquisition orbit and the related reconstruction algorithm were compared to those obtained using a single-circle cone beam geometry and Feldkamp's algorithm in terms of reconstruction accuracy. The results of the study demonstrate that the circle-plus-two-arcs cone beam orbit is achievable in practice. Also, the reconstruction accuracy of cone beam reconstruction is significantly improved with the circle-plus-two-arcs orbit and its related exact CB-FPB algorithm, as compared to using a single circle cone beam orbit and Feldkamp's algorithm.

Measurement of breast tissue composition with dual energy cone‐beam computed tomography: A postmortem study

“…System parameters, including optimized spectra and gantry geometry, have been extensively investigated by several research groups. 25,[27][28][29][30][31][32] An initial clinical study suggests that the cone beam breast CT is significantly better than mammography for visualization of soft tissue lesions. 26 A recent clinical study has also shown that breast CT has a significantly lower anatomical noise than mammography and breast tomosynthesis, providing the ultimate solution to eliminate the anatomical noise induced by overlap of the breast tissue.…”

Flat panel computed tomography of human ex vivo heart and bone specimens: initial experience

“…First results on experimental CT systems combining cone-beam CT scanners and FPD technology have been published recently [8,19,20]. These results are promising, and development is ongoing.…”

Cone-Beam Computed Tomography for Breast Imaging

“…Several investigations of simulations, phantom studies, and preliminary patient imaging have shown CBCT to be an imaging tool with superior contrast resolution and sufficient spatial resolution which can potentially result in a higher positive predictive value than mammography in the detection of cancer , Chen, 2003Ning et al, 2001Ning et al, , 2002, Ning, Tang et al, 2003, Ning et al, 2004. High-resolution real-time flat panel detector (FPD) systems have recently been introduced.…”