Model of the point spread function of monolithic scintillator PET detectors for perpendicular incidence
Schematic representation of the detector investigated: A 20 mm thick crystal read out by two Hamamatsu S8550SPL APD arrays in DSR geometry. The thick arrow indicates a test beam of annihilation photons incident at some arbitrary position on the front surface of the detector. Dimensions are indicated in mm.
Schematic representation of the geometry of the test beam of annihilation photons used to measure detector PSFs (not to scale).
Cross-sections of the measured (solid circles) and fitted (solid curve) , and cross-section of the corrected (dashed curve). was obtained using test data in the range and , and . The inset shows the same data plotted semilogarithmically.
Cross-sections along the -axis of the distributions (solid black curve), (solid gray curve), (dashed curve), and (dotted curve) for . The inset shows the same data plotted semilogarithmically.
FWHM and FWTM of measured and corrected as a function of the beam diameter in the test data. All 1D-PSFs were obtained using the same reference data recorded with a beam diameter FWHM with , test data in the range , and the value of that minimized .
FWHM of measured as a function of the beam diameter in the reference data, for various values of . Each was created using the same set of test data recorded at in the range .
(a) Standard deviation of measured and (b) residual sum of squares resulting from fitting the model to the same , as a function of the equivalent noise charge in the test data (circles) and in the reference data (squares). The values on the horizontal axis represent the noise added to the of electronic noise per channel already present in the experimental data. At each data point, the value of that minimized for that particular noise level was used.
Summary of the PSF models for an infinitesimally small beam diameter and for a finite beam diameter. In both models, it is assumed that .
Properties of the crystal investigated.
Widths of cross-sections along the and axes through the measured and corrected , obtained with .
Widths of cross-sections along the and axes through the distributions , , and corresponding to the PSFs listed in Table III.
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