9 March 2018 Geometric calibration for a next-generation digital breast tomosynthesis system using virtual line segments
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Our next-generation tomosynthesis (NGT) system prototype introduces additional geometric movements to conventional Digital Breast Tomosynthesis (DBT) acquisition geometries, to provide isotropic super-resolution. These movements include x-ray source movement in the posteroanterior (PA) direction and detector movement in the z-direction (perpendicular to the breast support). The desired benefits of the NGT system are only achievable with precise geometric calibration. In our previous work, a geometric phantom with 24 point-like ball bearings (BB’s) at four different magnifications was designed and a geometric calibration method that minimizes the difference between the projected locations and the calculated locations of BB’s was tested. This study investigates a new calibration method using the same phantom, utilizing projected 2D equations of virtual line segments created by any two BB’s for more precise reconstruction of the various acquisition modes of the NGT system. The geometric parameters were solved with two approaches: (1) solving each projection individually and (2) solving all projections simultaneously. Furthermore, two algorithms to compensate for any possible inaccuracy in BB locations within the phantom, presumably by less than desired manufacturing precision, were developed and compared: (1) manually identifying and removing poorly positioned BB’s and (2) performing an iteration to re-calculate the BB locations. Magnification digital breast tomosynthesis was also performed to test the calibration method further. Tomographic image reconstructions successfully demonstrated isotropic super-resolution and magnified super-resolution.
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Chloe J. Choi, Chloe J. Choi, Trevor L. Vent, Trevor L. Vent, Raymond J. Acciavatti, Raymond J. Acciavatti, Andrew D. A. Maidment, Andrew D. A. Maidment, "Geometric calibration for a next-generation digital breast tomosynthesis system using virtual line segments ", Proc. SPIE 10573, Medical Imaging 2018: Physics of Medical Imaging, 105730D (9 March 2018); doi: 10.1117/12.2294634; https://doi.org/10.1117/12.2294634

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