Explain why resolution of the PET scanner is typically worse away from the center of the scanner

Suppose a PET scanner has 1,000 detectors packed tightly around a circle of diameter of 1.5 m.

(a) What is the approximate size (width) of each detector? Explain the tradeoff between using deep (long) and shallow (short) detectors.

(b) What is the purpose of coincidence detection in PET? What is a nominal time interval defining a coincidence ‘‘event window’’ for PET? Explain why is it undesirable to make the event window (1) smaller or (2) longer.

(c) Assume there is no ‘‘wobbling’’ or ‘‘dichotomic’’ motion of the PET gantry. What is the line integral sampling interval (which has the symbol T in CT) in the center of the scanner? Assuming the usual sampling ‘‘rule of thumb’’ from CT, how many pixels would be in a typical PET image. Explain why motion of the PET gantry is desirable.

(d) Explain why resolution of the PET scanner is typically worse away from the center of the scanner

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Explain why attenuation is not a big problem in PET.

Consider a 2-D object consisting of two triangle compartments, as shown in Figure P9.4. Suppose a solution containing a 511 KeV gamma ray emitting radionuclide with concentration f = 0.5….

Give the mean and the variance of the reconstructed image, mean[ˆ f(x, y)] and var[ˆ f(x, y)].

Ignoring the inverse square law and attenuation, an approximate reconstruction for SPECT imaging is given by where c˜() =  {||W()} and W() is a rectangular windowing filter that cuts off at = 0…..

Find the numerical responses in each to an event in crystal C(4, 6).

Suppose a PET detector comprises four square PMTs (arranged as a 2 by 2 matrix) and a single BGO crystal with slits made in such a way that it is….