Small-field imaging properties of narrow energy band X-ray beamsfor mammography
Gambaccini, M.; Taibi, A.; Del Guerra, A.; Frontera, F.
Nuclear Science Symposium and Medical Imaging Conference Record, 1995., 1995 IEEE
Volume 3, Issue , 21-28 Oct 1995 Page(s):1388 - 1391 vol.3
Digital Object Identifier 10.1109/NSSMIC.1995.500261
Summary:X-ray imaging with low-energy, narrow-band, and tunable radiation
offers the possibility of reducing dose and improving image contrast. We
investigate the production of narrow energy band X-ray beams with a
standard X-ray tube by using Bragg diffraction on mosaic crystals for
mammography application. Quasi-monochromatic X-ray beams
(ΔE/E~0.1) have been produced in the mammography energy range.
Small-field (1.1×3.0 cm2) radiographs of a plexiglas
phantom 3.6 cm thick were obtained with 18, 20, and 22 keV
quasi-monochromatic beams and a conventional film/screen combination for
mammography. Images showed a nonuniformity in the irradiation field. A
digital detector was used as imaging system to correct the phantom
radiographs for this uneven illumination across the image. The overall
contrast of the images decreases with increasing energy of the beam from
18 keV to 22 keV. A measurement of the resolving power of the reflected
beam has shown an asymmetric unsharpness along the two dimensions of the
image plane. The actual focal spot has a size of about 0.2×0.05 cm
2
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