Quiz 1- Lecture 4: PET

Question 1

What does PET stand for?

Answer 1

Positron emission tomography

Question 2

What is positron emission tomography (PET) based on?

Answer 2

The physical properties of isotopes- radioactive forms of simple atoms (like hydrogen, oxygen, fluorine, etc.) emitting positrons when they decay

Question 3

The atoms of each chemical element have a defining and…
BUT CRUCIALLY

Answer 3

Same number of protons and electrons
NOT NEUTRONS, whose numbers can vary

Question 4

Isotopes are…

Answer 4

Atoms with the same number of protons but different numbers of neutrons

Question 5

Which is the radioactive isotope?
Protium (1H), Deuterium (2H), Tritium (3H)

Answer 5

Tritium (3H)- 2 NEUTRONS

Question 6

What is a positron?

Answer 6

Antiparticle of an electron

Question 7

A positron has all the properties of an electron except for…

Therefore, a positron can simply be considered…

Answer 7

The polarity of the electrical charge, which is POSITIVE

An electron having positive unit electrical charge

Question 8

What happens whenever an electron and a positron come close?

Answer 8

They annihilate each other and produce energy in the form of photons

Question 9

Basic properties of positrons (3):

Answer 9

• Rest mass= 9.11x10^-31 kg = 0.511 MeV/c^2
• Electrical charge= +1.602x10^-19 C
• Internal structure: Believed to have no internal structure

Question 10

Graph:
Each smaller square represents the nucleus of a known…
Black square represents…
All other squares represent…

Answer 10

Stable or radioactive isotope
The stable isotope nuclei
The nuclei of radioactive isotopes

Question 11

Fluorine F18 (3 characteristics):

Answer 11

• Decays by positron
• (B+) emission
• Has a half-life of 109.7 minutes

Question 12

What is it called when Oxygen-18 turns to Fluorine-18?

Answer 12

Nuclear transmutation

Question 13

Adding a proton means…

Answer 13

Going up on diagram

Question 14

Removing a neutron means…

Answer 14

Going left on diagram

Question 15

Labels on PET diagram:

Answer 15

• Positron-emitting nucleus
• Positron path
• Positron-Electron annihilation
  -Distance between positron-emitting nucleus and positron-electron annihilation is ~ 0.5 mm
• annihilation photons on either side of diagram

Question 16

During 1925-26, quantum theories were proposed that…
HOWEVER

Answer 16

Accurately described the energy levels of electrons in atoms
These equations needed to be adapted to Einstein’s theory of relativity

Question 17

In 1928, Paul Dirac…

Answer 17

Formulated a fully relativistic quantum theory

Question 18

What did Paul Dirac’s equation do?

What happened later?

Answer 18

The equation gave solutions that he interpreted as being caused by a particle equivalent to the electron but with a positive charge

This particle, the positron, was later confirmed through experiments

Question 19

Who was from Tallahassee, Florida?

Answer 19

Paul Dirac
The Nobel Prize in Physics 1933
“For the discovery of new productive forms of atomic theory”

Question 20

In developing the quantum mechanical theory, Dirac predicted that…

Answer 20

All matter has a kind of mirror image- antimatter

Question 21

What should a particle and its antiparticle have, if charged?

Answer 21

Opposite charges

Question 22

By studying the… in a …, in 1932…

Answer 22

Tracks of cosmic ray particles; Cloud chamber; Carl Anderson discovered a positively-charged particle with a mass seemingly equal to that of an electron

Question 23

Who discovered the positron?

Anderson’s particle…

Answer 23

Carl Anderson (Nobel Prize in Physics 1936)

Was the first antiparticle proven by experiment and was named a “positron”

Question 24

This wonderful item is a… that was used by… and Seth Neddermeyer between 1935 and 1941 at Caltech

Answer 24

Cloud chamber; Carl Anderson

Question 25

The cloud chamber served as the…

Answer 25

Prototype for a larger (3 ft diameter) chamber that was carried in a B-29 aircraft from 1948 to 1950 to study cosmic rays at high altitudes

Question 26

This particular chamber is unusual in that…

What is the advantage provided?

Answer 26

The piston is glass rather than metal

The advantage provided by the glass piston is that it allowed the chamber to be illuminated from below rather than from the side as in conventional designs