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Strips device and procedure for determining the location and reaction time of the gamma quanta and the use of the device to determine the location and reaction time of the gamma quanta in positron emission tomography
Strips device and procedure for determining the location and reaction time of the gamma quanta and the use of the device to determine the location and reaction time of the gamma quanta in positron emission tomography
A strip device for determining the location and reaction time of the gamma quantum, the device comprising a scintillation chamber, in which the scintillation chamber (1) has an internal cylindrical surface in which a plurality of strips are arranged (8) of the scintillator, in which the surfaces of the strips (8) of the scintillator are configured to reflect photons that fall on it from inside the scintillation chamber at an angle greater than a limit angle, each strip being optically connected from the scintillator to photomultipliers (11) for the reception, through light guides (10) of light photons, resulting from the gamma quant absorbed in the scintillator material, in which the energy of the gamma quantum is completely transferred to an electron of the scintillator by means of a photoelectric effect or partially by means of a Compton effect, which reaches the leading or trailing edge of the strip (8), and wherein the device additionally comprises an electronic system for the determination of the location of the annihilation points along LOR lines, the system being characterized in that it is configured to: - select events for which the signals are recorded within a time interval set on a pair of strips (8) of the scintillator separated by a relative distance, - and for each selected event, - determine the point of impact of the gamma quantum in a plane perpendicular to the longitudinal axis of the strip (8) of the scintillator from the position of the strip (8) of the scintillator that recorded the signal, - and for each strip (8) of the scintillator of the pair of strips (8) of the scintillator that recorded a signal for the selected event: - determine the position of the impact on the strip (8) of the scintillator along the scintillation chamber based on the time difference (t_anterior - t_posterior) between the time (t_anterior) me given in the previous photomultiplier (11) and the time (t_posterior) measured in the posterior photomultiplier (11) of the strip (8) of the scintillator, - determine the time (t1, t2) in which the quantum gamma interacted in each strip (8) of the scintillator as the arithmetic mean of the time (t_anterior) measured in the previous photomultiplier (11) and the time (t_posterior) measured in the rear photomultiplier (11) of each strip (8) of the scintillator, - determine the energy of the electron of the scintillator to which the gamma quantum energy was transferred by means of the Compton or photoelectric effect, based on the amplitudes of the signals in the photomultipliers (11) on both sides of the strips (8) of the scintillator, - and for each selected event: - determine the line of LOR based on the determined positions of the point of impact on the two strips (8) of the scintillator of the pair of strips (8) of the scintillator, - determine the place of annihilation along the line of LO R based on the times (t1, t2) determined when the gamma quantum interacted in the strips (8) of the scintillator, - provide a tomographic image from a set of reconstructed LOR lines and the location of the annihilation points to along these lines determined by the selected events, - and in which the strips (8) of the scintillator are made of doped plastic with atoms with atomic number of at least 50.
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