Abstract: The present invention discloses a method and system for performing three-dimensional computerized tomography imaging of a region of interest of an object. In the present invention, a scanning trajectory is provided about the object. The scanning trajectory includes a first scanning circle, a second scanning circle, and a helical scanning path connecting the first scanning circle and the second scanning circle. The scanning trajectory is then sampled with a plurality of cone beam source positions. Cone beam energy is emitted along the scanning trajectory from each of the plurality of cone beam source positions towards a portion of the object. Cone beam energy passing through the object is acquired on a detector as cone beam projection data. The cone beam projection data is then masked with a plurality of masks. Each of the masks remove cone beam projection data that is outside the region of interest of the object and retain cone beam projection data that is within the region of interest of the object.

Abstract: A system for recording fewer of the events that are caused by unwanted photons with greater stability. The system locally determines the energy spectrum and fits for each pixel of the image the determined energy spectrum with a modified trial function composed of: a photopeak component of known energy shape, Compton scatter components having theoretically derived energy shapes and, when applicable, also measured or calculated energy spectra of other unwanted photons. The modified trial function also takes into consideration unknown local deviations in the outputs of electronic components. The amplitude of the photopeak distribution resulting from the fit is used to obtain the local content of wanted interactions in the image. This enables removal of Compton contamination and also the contamination caused by interaction of the gamma photons with lead components.

Abstract: In an optical recording medium having concave and convex type signal pits formed on a substrate surface, a reflection layer is formed on the signal pits in such a manner that a reflection index of an interior of the signal pits is higher than a reflection index at a periphery of the signal pits with respect to a given reproduction laser beam wavelength. In an optical recording medium having a phase change recording layer which reversibly changes optical states upon application of laser energy, a structural phase difference between a reflection beam of non-recorded regions and a reflection beam of recorded regions of the optical recording medium with respect to the wavelength of a reproduction laser beam is in a range of (0.5-1.5)+2 n.pi. radians, where n is an integer. The phase change recording layer has principle components of Ge-Sb-Te or Sb-Se.