Purpose: A dual modality SPECT-CT prototype system dedicated to uncompressed breast imaging (mammotomography) has been developed. The computed tomography subsystem incorporates an ultrathick K-edge filtration technique producing a quasi-monochromatic x-ray cone beam that optimizes the dose efficiency of the system for lesion imaging in an uncompressed breast. Here, the absorbed dose in various geometric phantoms and in an uncompressed and pendant cadaveric breast using a normal tomographic cone beam imaging protocol is characterized using both thermoluminescent dosimeter (TLD) measurements and ionization chamber-calibrated radiochromic film. Methods: Initially, two geometric phantoms and an anthropomorphic breast phantom are filled in turn with oil and water to simulate the dose to objects that mimic various breast shapes having effective density bounds of 100% fatty and glandular breast compositions, respectively. Ultimately, an excised human cadaver breast is tomographically scanned using the normal tomographic imaging protocol, and the dose to the breast tissue is evaluated and compared to the earlier phantom-based measurements. Results: Measured trends in dose distribution across all breast geometric and anthropomorphic phantom volumes indicate lower doses in the medial breast and more proximal to the chest wall, with consequently higher doses near the lateral peripheries and nipple regions. Measured doses to the oil-filled phantoms are consistently lower across all volume shapes due to the reduced mass energy-absorption coefficient of oil relative to water. The mean measured dose to the breast cadaver, composed of adipose and glandular tissues, was measured to be 4.2 mGy compared to a mean whole-breast dose of 3.8 and 4.5 mGy for the oil-and water-filled anthropomorphic breast phantoms, respectively. Conclusions: Assuming rotational symmetry due to the tomographic acquisition exposures, these results characterize the 3D dose distributions in an uncompressed human breast tissue volume for this dedicated breast imaging device and illustrate advantages of using the novel ultrathick K-edge filtered beam to minimize the dose to the breast during fully-3D imaging.

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2011Elucidating the nature of neutrino oscillation continues to be a goal in the vanguard of the efforts of physics experiment. As neutrino oscillation searches seek an increasingly elusive signal, a thorough understanding of the possible backgrounds becomes ever more important.Measurements of neutrino-nucleus interaction cross sections are key to this understanding. Searches for ν μ → ν e oscillation-a channel that may yield insight into the vanishingly small mixing parameter θ 13 , CP violation, and the neutrino mass hierarchy-are particularly susceptible to contamination from neutral current single π 0 (NC 1π 0 ) production. Unfortunately, the available data concerning NC 1π 0 production are limited in scope and statistics.Without satisfactory constraints, theoretical models of NC 1π 0 production yield substantially differing predictions in the critical E ν ∼ 1 GeV regime. Additional investigation of this interaction can ameliorate the current de ciencies.e Mini Booster Neutrino Experiment (MiniBooNE) is a short-baseline neutrino oscillation search operating at the Fermi National Accelerator Laboratory (Fermilab). While the oscillation search is the principal charge of the MiniBooNE collaboration, the extensive data (∼ 10 6 neutrino events) offer a rich resource with which to conduct neutrino cross section measurements. is work concerns the measurement of both neutrino and antineutrino NC 1π 0 production cross sections at MiniBooNE. e size of the event samples used in the analysis exceeds that of all other similar experiments combined by an order of magnitude. We present the rst measurements of the absolute NC 1π 0 cross section as well as the rst differential cross sections in both neutrino and antineutrino mode. Speci cally, we measure single differential cross sections with respect to pion momentum and pion angle. We nd the ux-averaged, total cross sections for NC 1π 0 production on CH 2 to be AcknowledgementsImagine my dismay at learning that I did not become the kind of doctor that can order people to take off their pants. Awkward! I must have checked the wrong box on the form.Regardless, it would impolitic of me to fail to acknowledge those I worked (and played) with on my way to becoming a Doctor of Philosophy. e process has been occasionally tedious and quite oen challenging but generally fascinating and always enjoyable. Mathematica, I speak to you as a person because no soware could possibly be so ckle.I liken you to television' s Dr. Gregory House: abrasive and uncooperative to a fault, but always producing beautiful results. I invested countless hours in bending you to my will.Sometimes you would crash in protest and I would lose the day' s work. Well played, Mathematica! Well played, indeed. Aer much struggling, I was able to reliably produce gures in Mathematica, and very oen I would receive compliments for those gures. All told, the ends did justify the means.I am profoundly grateful to the friends in New Haven who provided much needed diversions: Tom, Ethan, Jerry, Kevin, Will, Peter...