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

find the cost of your paper

calculate: (a) the fresh hydrogen feed, (b) the purge rate required, (c) the composition of the reactor outlet stream.

Aniline is produced by the hydrogenation of nitrobenzene. A small amount of cyclohexylamine is produced as a by-product. The reactions are: C6H5NO2 + 3 H2 ? C6H5NH2 + 2 H2O C6H5NO2 + 6 H2 ?….

Determine the interfacial conditions at each end of the column.

Height of a packed-tower absorber a packed tower of the type described in Example 23.5-2 is to be used for removing 90% of the cyclohexane from a cyclohexane-air mixture by….

Determine the thrust available to propel the cart.

A CO2 cartridge is used to propel a small rocket cart. Compressed gas, stored at 35 MPa and 20C, is expanded through a smoothly contoured converging nozzle with 0.5 mm….