(c) A system with a spatial resolution of 5 mm is better than a system
with a spatial resolution of 8 mm. True or false?
- The intrinsic resolution of a gamma camera depends on:
(a) The thickness of the NaI(Tl) detector. True or false?
(b) The energy of the g-ray. True or false?
(c) The width of the pulse-height window. True or false?
(d) The number of counts collected. True or false?
- (a) What is the best photon energy for imaging with a gamma
camera?
(b) Why is a thinner NaI(Tl) detector used in a gamma camera?
(c) Intrinsic resolution improves with higher g-ray energy. True or false?
(d) Spatial resolution of a gamma camera improves as the number of
photomultiplier tubes is increased. True or false?
- For a gamma camera with a parallel-hole collimator,
(a) The spatial resolution increases with decreasing detector thickness.
True or false?
(b) The collimator efficiency decreases with increasing collimator
length. True or false?
(c) The spatial resolution increases with decreasing collimator length.
True or false?
(d) High-energy collimators have higher efficiency and resolution than
low-energy collimators. True or false?
(e) The best resolution is obtained at the face of the parallel-hole col-
limator. True or false?
- What are the effects of the following factors on the spatial resolution
and sensitivity of a gamma camera?
(a) Photomultiplier (PM) tubes with higher quantum efficiency
(b) A wider “window” on the pulse-height analyzer (PHA)
(c) Increasing the activity of 99mTc from 5 mCi (185 MBq) to 15 mCi
(555 MBq)
(d) Increasing the diameter of the collimator hole
(e) Adding more tissue between the collimator face and the patient’s
organ
(f) Using a diverging collimator
(g) Increasing the source-to-collimator distance for a parallel-hole
collimator
(h) Using a g-ray of higher energy, which penetrates the septum of the
collimator
- (a) In routine practice, how is the spatial resolution of a gamma camera
checked?
(b) The full width at half maximum of the line spread function of a
gamma camera does not give a true picture of spatial resolution.
Why?
(c) What is the modulation transfer function (MTF) of a system?
(d) A system gives the best spatial resolution when its MTF is equal to
- True or false?
Questions 137
