Radiopharmaceuticals Flashcards
What is a radiopharmaceutical?
Radioactive agent used for diagnostic or therapeutic procedures
What is the most common radioisotope for diagnosis?
Tc-99m
How do you find the mass number?
Protons + Neutrons
How do you find the atomic number?
Protons
What are isotopes?
Same number of protons, but different number of neutrons
What is a radionuclide?
Atom that has an unstable nucleus (excess nuclear energy)
Where exactly does decay occur?
Parent nucleus
What does the parent nucleus produce?
Daughter nucleus
A nuclide with an atomic number greater than ____ is radioactive
83
Is radioactive decay random?
Yes
Can you predict when one particular atom will decay?
No; unless it is a collection of atoms of a single element
What does the rxn rate of a first-order rxn tell you?
Rxn rate = directly proportional to concentration of one of the reactants
What kind of order process does rate of decay represent?
First-order
What is the physical half-life?
Amount of time necessary for the radioactive atoms to decay to 1/2 their original number
What is the biological half-life?
Amount of time required for the body to metabolize/eliminate 1/2 of administered dose
What is the effective half-life?
Time required for an administered radiopharmaceutical dose to be reduced to 1/2 as a result of both physical decay and biological mechanisms
(p*b)/(p+b)
Ionizing vs non-ionizing radiation
Which causes e- to be knocked out of molecules?
Ionizing
Radioactive decay is an (ionizing/non-ionizing) radiation
Ionizing
What are the 3 principle types of radioactive decay w/ charge?
Alpha = +2 Beta = -1 Gamma = no charge
In an alpha emission, what kind of element is emitted?
Helium
As a result of an alpha emission, the new element form an atomic number with ___ units (higher/lower) and a mass number ____ units (higher/lower)
atomic number = 2 units higher
mass number = 4 units lower
What is transmutation?
Changing one element to another
What gives the alpha particle a relatively large mass compared to other ionizing radiation particles?
Neutrons and Protons
Because of the alpha particle’s large mass, what is some good news?
Low speed and low penetrating distance
What line/pathway do alpha particles follow?
Tend to travel in a straight line
Ionization in a small area
In beta particles, what is being changed?
Neutron is converted to a proton and an electron
Emission of a beta particles transforms what?
Element into a new element with same mass number but 1 unit higher of atomic number
Compared to a alpha particle, a beta particle is…
smaller and faster
penetrates better, but less damage
Alpha particles are considered (internal/external) hazard
internal
Beta particles are considered (internal/external) hazard
Both
Gamma ray is a high energy ionizing radiation in the form of ________ energy
electromagnetic energy
Gamma rays are weightless packets of energy called ________
protons
When are gamma rays usually emitted?
Along with alpha/beta particles during decay
Gamma particles are considered (internal/external) hazard
Both
What is a positron emission and what is the result of it?
“Positive e-“ is emitted from nucleus
Atomic number = one unit lower
Mass number = same
What is an electron capture and what is the result of it?
Extra electron is captured by nucleus
With a proton, it forms a neutron
What is the primary (or viable) decay mode for isotopes that have relative superabundance of protons?
Electron capture
What is the neutron particle emitted by?
Nuclear fission
Ionizing radiation is characterized by two physical measurements, what are they?
- Intensity/activity
2. Energy
What are some instruments used to detect intensity/activity of ionizing radiation + units
- Geiger-Muller or proportional counter
- Scintillation counter
Ci U.S. unit and becquerel (Bq [SI unit])
How does ferric hexacyanoferrate work?
Traps cesium and thallium ions in GI and interrupts their reabsorption back to circulation
How does DTPA work?
Chelating agent used to eliminate radionuclides. Works in the blood where it competes with various biological ligands
