Radiopharm Flashcards
Non-ionizing radiation vs ionizing radiation
Non-ionizing
- not enough energy to ionize atoms/molecules (remove electrons
Ionizing
- enough energy to remove electrons from atoms/molecules
What type of subatomic particles are in directly ionizing and indirectly ionizing radiation
Directly ionizing (charged)
- electrons, protons, heavy ions, alpha particles
Indirectly ionizing (neutral)
- photons, neutrons
What is the condition for equilibrium?
When daughter’s half life is shorter than parent’s
What are the 2 types of equilibrium
Secular equilibrium: parent life is 100-1000x daughter’s life
Transient equilibrium: parent life is 10x daughter’s half-life
What are the 2 important methods by which gamma rays interact with matter they pass through?
- Photoelectric interaction
- Compton Interaction
Explain photoelectric interaction
Photon interacts with atom, ejects an orbital electron from the atom
- entire energy of photon is used
Explain compton interaction
Photon TRANSFERS SOME energy to eject an orbital electron
- remaining energy is used to scatter the photon at an angle
Brachytherapy: sealed source and unsealed source are part of what type of radiation
Internal
What type of info is given from imaging? Ex?
Spatial info
- CT scan, MRI
What type of info is given from functional imagine? Ex?
Temporal information (changes in blood flow/metabolism)
- fCT
- fMRI
- SPECT
- PET
What can a radiopharmaceutical be used for? How can they be given to patients?
Used for
- Diagnostic medical imaging
- therapeutic purpose
Given by
- Injection
- Inhalation
- Oral
Define
physical half-life
Biologic half-life
Effective half-life
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)
What are the 2 components of a radiopharmaceutical
- Radionuclide/radioactive isotope
- Carrier module: to deliver the isotope to the desired area
What are the ideal characterisitcs of radiopharm
- 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
What is the an important factor for safety of use in radiopharmaceuticals
Production of ready to use kit (individual doses)
What is the most common radioisotope for diagnosis/imaging?
Technetiium-99m
In methods of production of radioisotopes:
explain NUCLEAR FISSION
for nuclides with high atomic number
- bombarding with neutrons, using nuclear reactor
In methods of production of radioisotopes:
explain CHARGED PARTICLE BOMBARDMENT
Bombarding with charged particles
- using cyclotrons
In methods of production of radioisotopes:
explain NEUTRON BOMBARDMENT
bombarding with neutrons
- using a nuclear reactor
In methods of production of radioisotopes:
explain RADIONUCLIDE GENERATOR
For nuclides with short half life
- separating daughter radionuclide from parent by physical or chemical separation (elution)
Radionuclide generator
Output characteristics?
Separation by?
Human intervention?
Production of beta particle?
Good example?
- 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
- Separation (elution) is done by affinity OR ion-exchange chromatography
Differentiate between stohastic and deterministic effects
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
