Radiopharm

Question 1

Non-ionizing radiation vs ionizing radiation

Answer 1

Non-ionizing
- not enough energy to ionize atoms/molecules (remove electrons

Ionizing
- enough energy to remove electrons from atoms/molecules

Question 2

What type of subatomic particles are in directly ionizing and indirectly ionizing radiation

Answer 2

Directly ionizing (charged)
- electrons, protons, heavy ions, alpha particles

Indirectly ionizing (neutral)
- photons, neutrons

Question 3

What is the condition for equilibrium?

Answer 3

When daughter’s half life is shorter than parent’s

Question 4

What are the 2 types of equilibrium

Answer 4

Secular equilibrium: parent life is 100-1000x daughter’s life

Transient equilibrium: parent life is 10x daughter’s half-life

Question 5

What are the 2 important methods by which gamma rays interact with matter they pass through?

Answer 5

1. Photoelectric interaction
2. Compton Interaction

Question 6

Explain photoelectric interaction

Answer 6

Photon interacts with atom, ejects an orbital electron from the atom
- entire energy of photon is used

Question 7

Explain compton interaction

Answer 7

Photon TRANSFERS SOME energy to eject an orbital electron
- remaining energy is used to scatter the photon at an angle

Question 8

Brachytherapy: sealed source and unsealed source are part of what type of radiation

Answer 8

Internal

Question 9

What type of info is given from imaging? Ex?

Answer 9

Spatial info
- CT scan, MRI

Question 10

What type of info is given from functional imagine? Ex?

Answer 10

Temporal information (changes in blood flow/metabolism)
- fCT
- fMRI
- SPECT
- PET

Question 11

What can a radiopharmaceutical be used for? How can they be given to patients?

Answer 11

Used for
- Diagnostic medical imaging
- therapeutic purpose

Given by
- Injection
- Inhalation
- Oral

Question 12

Define
physical half-life
Biologic half-life
Effective half-life

Answer 12

physical half-life
- time for half the radioisotope to decay

Biologic half-life
- time for half of the radioactive to leave the body

Effective half-life
- combined biological and physical half lives)

Question 13

What are the 2 components of a radiopharmaceutical

Answer 13

1. Radionuclide/radioactive isotope
2. Carrier module: to deliver the isotope to the desired area

Question 14

What are the ideal characterisitcs of radiopharm

Answer 14

• easy availability
• short effective half-life
• Maximum target activity, Minimum non-target activity
• Particle emissions
  
  • a & B particles cause more radiation damage than gamma rays
  • a emitters never used for in vivo diagnostic studies
  • Radionuclide must emit a gamma radition between 30-300 Kev

Question 15

What is the an important factor for safety of use in radiopharmaceuticals

Answer 15

Production of ready to use kit (individual doses)

Question 16

What is the most common radioisotope for diagnosis/imaging?

Answer 16

Technetiium-99m

Question 17

In methods of production of radioisotopes:
explain NUCLEAR FISSION

Answer 17

for nuclides with high atomic number
- bombarding with neutrons, using nuclear reactor

Question 18

In methods of production of radioisotopes:
explain CHARGED PARTICLE BOMBARDMENT

Answer 18

Bombarding with charged particles
- using cyclotrons

Question 19

In methods of production of radioisotopes:
explain NEUTRON BOMBARDMENT

Answer 19

bombarding with neutrons
- using a nuclear reactor

Question 20

In methods of production of radioisotopes:
explain RADIONUCLIDE GENERATOR

Answer 20

For nuclides with short half life
- separating daughter radionuclide from parent by physical or chemical separation (elution)

Question 21

Radionuclide generator
Output characteristics?
Separation by?
Human intervention?
Production of beta particle?
Good example?

Answer 21

• Output is sterile, pyrogen free
  
  • Separation (elution) is done by affinity OR ion-exchange chromatography
    ○ Using 0.9% saline solution
  • Minimal human intervention, to reduce radiation exposure
  • Production of beta particle is not desired (high radiation dose, bad for human)
    Good example: Technetium-99m

Question 22

Differentiate between stohastic and deterministic effects

Answer 22

Stochastic effects: no threshold dose
* Severity is independent of dose
○ Radiation induced cancer, genetic effects
Deterministic (non-stochastic effects): threshold dose exists
* Severity depends on dose
Cataracts, erythema, sterilization, effects on fetus/embryo throughout gestation