Experiments with uniform and textured phantoms were also conducted. Simulations of two different phantoms were performed: a “tube” phantom and a “lattice” phantom.
Using simulations and physical experiments, the SNR and CNR were compared with conventional DBT. To evaluate the impact of moving the x-ray source away from the chest wall, the signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were measured as a function of location within the reconstructed volume. Acquisition geometries tested in this study include the conventional (control), “T-shape,” and “bowtie” geometries. Here we evaluate strategies in DBT to avoid missing tissue while improving overall image quality. One well-known consequence of acquiring projections with the x-ray source anterior to the chest wall is that a small volume of tissue adjacent to the chest wall is missed.
A prototype, next-generation tomosynthesis (NGT) system has been developed that is capable of acquiring customized geometries with source motion parallel and perpendicular to the chest wall. The optimal tube voltage decreased to 42 kVp when the Al pre-filtration was increased to 3 mm.It is standard for the x-ray source in conventional digital breast tomosynthesis (DBT) acquisitions to move strictly along the chest wall of the patient. The optimal tube voltage varied slightly from 46 to 44 kVp as the breast thickness increases from 2 to 8 cm. Results: The optimal imaging parameters, which lead to the highest FOM, were found at a beam energy of 45 kVp with a splitting energy at 34 keV for an averaged breast thickness of 4 cm with a standard 0.75 mm Al pre-filtration. The figure-of-merit (FOM), which was defined as the decomposed iodine signal-to-noise ratio (SNR) with respect to the square root of the mean glandular dose (MGD), was chosen to optimize the imaging parameters, in terms of beam energy, splitting energy, and pre-filtrations for breast of various thicknesses and densities. Quantum efficiency of the detector was calculated based on the effective attenuation length in the Si strips. A 4 mm iodine signal with a concentration of 4 mg/ml was used to simulate more » the enhancement of a lesion. The breast was modeled as a mixture of adipose and mammary gland tissues with a breast density of 30%. The simulation traces the emission of photons from the x-ray source, attenuation through the breast and subsequent absorption in the detector. Methods: A computer simulation model using polyenergetic spectra from a tungsten anode x-ray tube and a Si-based photon-counting detector was evaluated for contrast-enhanced spectral mammography. Purpose: To investigate the feasibility of optimizing the imaging parameters for contrast-enhanced spectral mammography based on Si strip photon-counting detectors. It is also shown that below 5 ms static nonlinearities, likely caused by the need to use a large focus for cine acquisition, dominate the blurring process. Phantoms were 18.6-35.0 cm acrylic with an iohexol-equivalent disk placed at midthickness (35 mg/cm7 ms. Entrance exposure and large-area iodine signal-to-noise ratio (SNR) were measured with the SBDX prototype and compared to that of a clinical cardiac interventional system with image intensifier (II) and charge coupled device (CCD) camera (Philips H5000, MRC-200 x-ray tube, 72 kWp max). The scanning-beam digital x-ray (SBDX) system uses an inverse geometry, narrow x-ray beam, and a 2-mm thick CdTe detector to improve the dose efficiency of the coronary angiographic procedure.
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