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Formulas for predicting the absolute X-ray intensity spectra from both Bremsstrahlung and K characteristic X-rays have been developed. These formulas cover a wide range of target materials and target geometry conditions (incident and emission angle) and tube voltage range from 20 to 200kV. For the Bremsstrahlung Intensity Spectrum:vskip 3.5cm Where U tube voltage(kV); J tube current(mA); n&61 1.6; <i>P</i> &61 1.08x10^-6(<i>A/Z</i>^2.5;<i>k_{s}</i> &61 0.32; <i>k</i> &61 <i>K_{m}Z</i>²/<i>A; K</i> = <i>k</i>3/511. The theoretical value of <i>K_{m}</i> is 4.73x10¹⁴<i>keV/mAs.sr.keV</i>. For a Fluency with a Total Filtration of <i>d_{Al} g/cm</i>² Al: <i>F(E)dE = I(E)E^{-1}e^{-μAldAl}dEphotons/keV.mAs.sr</i>. This formula can be used at various incident angles (θi) andemission anglesfor different target material (A, Z, μ) for <i>U</i> from 20-200kV. The angular distribution <i>f</i>(θ) (defined = 1 when θ = 90^o and varies with <i>U</i>) requires definition by experimental measurements. According to this formula the Photon Fluency spectra at different tube voltages, different target angles and different emission directions are calculated and illustrated as spectral curves. There is a good agreement between the formula results and spectra measured by other authors. For K-Characteristic X-ray fluency:vskip 1.5cm Where n&61 1.61; <i>P</i> &61 1.08x10^-6(<i>A/Z</i>)^2.5; k is a factor of 1.0-2.5, which represents the effective depth of K photo production and increases with Z; θ<i>_{i}</i> and θ<i>_{r}</i> the electron incident and X-ray emission angles; Ψ(θ<i>_{i}</i>) &61 <i>cos</i>(7.89x10^-4θ2.6_i) an empirical angle function; <i>N(E_{i}</i>) the fluency of <i>E_{i}</i> characteristic X rays per mAs per solid angle; <i>E_{k}</i> the binding energy of the K sell; <i>F</i>_k the efficiency constant depends on Z; <i>f(E_{i}</i> the fractional emission of the <i>E_{i}</i> characteristic X rays; <i>J</i> the tube current; <i>U</i> the tube voltage. The recommended value of <i>F</i>_Kα, based on measured data, is 3.8-4.7x10^11<i>photon/mAs.sr</i> for values of Z from 25 to 50. The relationship between the target attentuation factor and different target materials, angles and voltages are discussed. This formula can be used at much wider situations and has good agreement with the measured data.

X-ray imaging exams are widely used procedures in medical diagnosis. Whenever an x-ray imaging procedure is performed, it is accompanied by scattered radiation. Scatter is a significant contributor to the degradation of image quality in breast CT. This work uses our understanding of the physics of Compton scattering to overcome the reduction in image quality that typically results from scattered radiation. By measuring the energy of the scattered photons at various locations about the object, an electron density (ρe) image of the object can be obtained. This work investigates a system modeled using a 2D cross-sectional view of a breast CT geometry. The ρe images can be obtained using filtered backprojection over isogonic curves. If the detector has ideal energy and spatial resolution, a single projection will enable a high quality image to be reconstructed. However, these ideal characteristics cannot be achieved in practice and as the detector size and energy resolution diverge from the ideal, the image quality degrades. To compensate for the realistic detector specifications a multi-projection Compton scatter tomography (MPCST) approach was introduced. In this approach an x-ray source and an array of energy sensitive photon counting detectors located just outside the edge of the incident fan-beam, rotate around the object while acquiring scattering data. The ρe image quality is affected by the size of the detector, the energy resolution of the detector and the number of projections. These parameters, their tradeoffs and the methods for the image quality improvement were investigated. The work has shown that increasing the energy and spatial resolution of the detector improves the spatial resolution of the reconstructed ρe image. These changes in the size and energy resolution result in an increase in the noise. Thus optimizing the image quality becomes a tradeoff between blurring and noise. We established that a suitable balance is achieved with a 500 eV energy resolution and 2×2 mm2 detector. We have also established that using a multi-projection approach can offset the increase in the noise.