Nuclear Medicine

Question 1

What are the forces holding an atom together?

Answer 1

Strong nuclear force

Coulomb (electric force)

Question 2

What is an Auger electron?

Answer 2

Another electron gets all the energy from an electron that drops down a level. This electron then flies off with all that excess energy.

Question 3

What happens to excess energy from a nucleus relaxing?

Answer 3

A gamma-ray is released

Can create an Auger electron (which in turn causes a characteristic x-ray to occur)

Question 4

How do Auger electrons cause x-rays?

Answer 4

An electron drops down a shell to fill the Auger electron’s place and a characteristic x-ray is released

Question 5

What symbol represents ‘Mass Number’?

Answer 5

A

Question 6

What symbol represents ‘Atomic Number’?

Answer 6

Z

Question 7

What does ‘A’ represent in nuclear medicine?

Answer 7

Mass number (number of proton+ neutrons)

Question 8

What does ‘Z’ represent in nuclear medicine?

Answer 8

Atomic number (number of protons/ electrons)

Question 9

What symbol represents ‘Neutron Number’?

Answer 9

N

Question 10

What does ‘N’ represent in nuclear medicine?

Answer 10

Neutron number

Question 11

What are Isotopes?

Answer 11

atoms with the same atomic number but different mass number

Question 12

What are Isobars?

Answer 12

atoms with the same mass number but different atomic numbers

Question 13

What are Isotones?

Answer 13

atoms with the same number of neutrons

Question 14

What is it called when nuclear decay transfers energy to an orbital electron rather than emitting a gamma ray?

Answer 14

internal conversion

Question 15

What factors make a nucleus unstable?

Answer 15

large mass number (everything > 209 unstable)
number of protons/ neutrons very different
odd number of protons: neutrons

Question 16

What are the generic names that atoms decay to/ from?

Answer 16

parent –> daughter

Question 17

What is an alpha particle?

Answer 17

2 neutrons, 2 protons

Question 18

What is a beta particle?

Answer 18

a free electron (or positron)

Question 19

What is a neutrino?

Answer 19

a massless chargeless particle that travels at the speed of light and almost never interacts with matter

Question 20

What is alpha decay?

Answer 20

when an alpha particle is emitted from the nucleus?

Question 21

What is beta minus decay?

Answer 21

A neutron turns into a proton and releases an electron (and anti-neutrino)

Question 22

What is beta minus decay also known as?

Answer 22

beta particle emission

Question 23

What is beta particle emission also known as?

Answer 23

beta minus decay

Question 24

What is beta plus decay also known as?

Answer 24

positron emission?

Question 25

What is positron emission also known as?

Answer 25

beta plus decay

Question 26

What is beta plus decay?

Answer 26

a proton turns into a neutron (and releases a positron)

Question 27

What is required for positron emission to occur

Answer 27

a proton-rich nuclide with at least 1022keV of excess energy

Question 28

What occurs after positron emission?

Answer 28

they interact almost immediately with a nearby electron and release two photons (511keV each)

Question 29

What is 'electron capture' in nuclear medicine?

Answer 29

an inner-shell electron is drawn into a nucleus and combines with a proton to form a neutron and neutrino

Question 30

What occurs after electron capture?

Answer 30

Electrons drop down to the inner shell and cause the release of either an auger electron or characteristic radiation

Question 31

What is a metastable state?

Answer 31

an excited nucleus that may stay in the unstable state for a number of hours

Question 32

What effects the rate of radioactive decay

Answer 32

only the number of unstable nuclei, unaffected by temperature pressure etc

Question 33

What are units of radioactive decay?

Answer 33

Becquerel (SI units) - 1 disintegraiton/ second Curie (historical/ USA units)

Question 34

What is a decay series?

Answer 34

a series of radioactive reactions that occur, when one radioisotope decays into another that is also radioactive

Question 35

What two types of particles can cause ionizing radiation?

Answer 35

charged particles | photons

Question 36

What large charged particles can cause ionising radiation?

Answer 36

alpha particles protons deutrons

Question 37

What are deuterons?

Answer 37

hydrogen particles with a neutron + proton

Question 38

How far do large charged particles travel?

Answer 38

not very far | 4cm in air, less in thicker tissue

Question 39

What metric is used for how much radiation energy ionizing particles release as they travel?

Answer 39

linear energy transfer

Question 40

What is pair production in nuclear medicine?

Answer 40

a photon splits into a positron and an electron

Question 41

What conditions are necessary for pair production to occur?

Answer 41

the photon needs to have at least 1022keV of energy

Question 42

What 3 processes make up photon attenuation in matter?

Answer 42

photo-electric effect compton scatter pair production

Question 43

What is used to measure photon radiation in nuclear medicine?

Answer 43

scintillators

Question 44

what is the most common scintillator in nuclear medicine?

Answer 44

Sodium Iodide (NaI)

Question 45

What are desirable properties for scintillators

Answer 45

high Z high light output highly transparent cheap

Question 46

What are some issues with Na I scintillators?

Answer 46

low mechanical stability | absorbs water from air (hygroscopic)

Question 47

What is used with scintillators to produce a measurable signal

Answer 47

a photomultiplier tube

Question 48

What does a scintillator do?

Answer 48

absorbs ionising radiation and releases visible light

Question 49

what does a photomultiplier tube do?

Answer 49

Converts light to electrons then amplifies massively

Question 50

What occurs with the signal from a photomultiplier tube in nuclear medicine?

Answer 50

Cleaned up and then processed by a pulse height analyser (PHA)

Question 51

What does a Pulse Height Analyser (PHA) do in nuclear medicine?

Answer 51

determines if the pulse is between a sweet lower/ upper boundary