Section 1

### Section 1: The Building Blocks of Nuclear Cardiology

The radiations typically used to image 201Tl are polyenergetic because:

a. electron capture creates multiple γ-ray emissions.

b. 201Hg K- and L-shell electrons have different binding energies.

c. there are multiple γ-ray emissions from 201Hg.

d. 201Tl γ-ray emissions are more abundant than χ rays.

b. Characteristic χ rays from 201Hg may come from both the K and L shells. Since the L shell has three substates each with unique binding energies, the characteristic χ-ray energies are different.

In the decay of 99mTc, internal conversion is responsible for:

a. characteristic χ rays.

b. Auger electrons.

c. β+ emissions.

d. particulate emissions.

d. Internal conversion is the competing process to isomeric transitions. While isomeric transitions are more probable in the decay of 99mTc to 99Tc, there are always some internal conversions. Internal conversions resolve the energy transition through the emission of electrons.

Photons undergoing Compton scatter in tissue:

a. can be identified by their energy.

b. are less abundant than the photoelectrons.

c. are not considered in radiation safety.

d. are more abundant than Compton electrons.

a. Photons that undergo Compton scatter are only partially absorbed. The trajectory of the photon is altered from its incident path by an angle θ. As this angle increases, the energy of the scattered photon decreases.

As the thickness of tissue overlying the heart increases:

a. the percentage of transmitted photons increases.

b. the number of photoelectrons decreases.

c. the amount of characteristic χ rays decreases.

d. the number of energy-degraded photons increases.

d. The attenuation of photons is a function of energy, the Z number of the material, and the thickness of the attenuator. Therefore, if energy and Z number remain constant but thickness increases, fewer photons will be transmitted.

Which of the following statements is wrong?

a. Absorbed dose ...

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