Deck 29: Nuclear Medicine and Molecular Imaging

Question 1

Scintillation detectors or gamma cameras use crystals that change:

A) x-rays into electrons.
B) radioactive emissions into light photons.
C) radioactive emissions into electrons.
D) radioactive emissions into electrical pulses.

Answer 1

radioactive emissions into light photons.

Question 2

PET scanners have to be close to the source of positrons because:

A) the positrons cannot travel very far.
B) the nuclides are so unstable.
C) of the examination radioactivity of the nuclides.
D) of the short half-lives of the nuclides.

Answer 2

of the short half-lives of the nuclides.

Question 3

If only one photon is detected and no other photon is observed during the time window for an annihilation pair,then:

A) the original event is discarded.
B) only the one photon is recorded.
C) the computer estimates the probable location.
D) the examination must be repeated in an hour.

Answer 3

the original event is discarded.

Question 4

The crystal used in gamma cameras is made of:

A) sodium iodide.
B) cesium-activated iodide.
C) thallium-activated sodium iodide.
D) lithium fluoride.

Question 5

One desirable characteristic of a radiopharmaceutical is:

A) long physical half-life in days.
B) millisecond effective half-life.
C) easily absorbed in surrounding tissues.
D) primary photon energy between 100 and 140 keV.

Question 6

One of the major benefits of fusion imaging with PET and CT is:

A) attenuation coefficients are the same.
B) radiation dose is less.
C) metabolic and anatomic evaluation is easier.
D) the same detector can be used for both.

Question 7

Unwanted photons or "noise" are reduced by using a:

A) pulse height analyzer.
B) collimator.
C) Geiger counter.
D) scintillator.

Question 8

The radiotracer for PET scanning is chosen for:

A) studies that will show only anatomy.
B) its long half-life compared with nuclear medicine.
C) its similarity to naturally occurring biochemicals.
D) faster examination times.

Question 9

Naturally occurring radionuclides are not used for nuclear medicine imaging because:

A) synthetic ones are cheaper.
B) there is a high patient dose from natural ones.
C) synthetic ones decay differently.
D) they are not strong emitters.

Question 10

When a positron and an electron combine,the result is annihilation radiation of:

A) two photons of 1.022 MeV.
B) two photons of 0.511 MeV.
C) two photons of 180 MeV.
D) multiple gamma photons.

Question 11

Collimators are used in nuclear medicine to:

A) cone down the beam.
B) limit patient dose from the radiation.
C) maintain signal strength.
D) keep scattered rays from entering the camera.

Question 12

The most common device used to produce nuclides for PET scanning is the:

A) high-frequency generator.
B) compact medical cyclotron.
C) linear accelerator.
D) pulse height analyzer.

Question 13

Which two are used primarily to image physiology? (Select all that apply.)

A) MRI
B) CT
C) PET
D) SPECT

Question 14

SPECT imaging produces images that:

A) are similar to those done in CT.
B) will show only large lesions.
C) require increased amounts of radionuclides.
D) show only motion.

Question 15

Half-life is described as the time required for:

A) half the nuclide to leave the body.
B) half the nuclide to disappear.
C) the nuclide to decay to half its original activity.
D) the original activity to increase by one half.

Question 16

The most common radionuclide used in nuclear medicine is:

A) technetium (^99mTc).
B) iodine (¹²³I).
C) thallium (²⁰¹Tl).
D) xenon (¹³³Xe).

Question 17

PET scanning is an examination that can visualize a patient's:

A) physiology.
B) anatomy.
C) soft tissue.
D) bone detail.

Question 18

An array of photomultiplier tubes (PMTs)is located:

A) in front of the crystal.
B) to the back of the crystal.
C) after the pulse height analyzer.
D) after the collimator.