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A compact, dual modality computed mammotomography (CmT) and single photon emission computed tomography
(SPECT) system for dedicated 3D breast imaging is in development. The CmT component utilizes novel, heavy K-edge
filtration to practicably narrow the energy spectrum of the cone-shaped x-ray beam incident on the patient's pendant,
uncompressed breast. This quasi-monochromatic beam in CmT is expected to improve discrimination of tissue with
very similar attenuation coefficients while restraining dose levels to below that of existing dual view mammography.
Our previous extensive simulation studies showed the optimal energy range that provides maximum dose efficiency for
a 50/50 adipose/glandular breast is in the 35-40keV range. This current study aims to experimentally validate previous
simulation results. Here, experimental pre-breast and post-breast collimated x-ray beam spectral measurements are
made under tube operating voltages between 40-100kVp using filter materials from Z=13-74, with K-edge values
spanning that of Ce (K=40.4keV), and using different attenuating thicknesses of filter material, approximately
equivalent to the 200th and 500th attenuating value layer (VL) thickness. Ce-filtered post breast spectra for 8cm to 18cm
breasts are measured for a range of breast adipose/glandular compositions. Evaluated figures of merit include mean
beam energy, spectral full-width at tenth-maximum, beam hardening and dose for the range of breast sizes.
Measurements are shown to corroborate the simulations, and both indicate that for a given dose a 200th VL of Ce
filtration may have the most optimal performance in the dedicated mammotomography paradigm.
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