nuclear med Flashcards
radiopharmaceutical
radioactive substance used in nuclear med imaging / treatment
tracer
another name for radiopharmaceutical
uptake
absorption / accumulation of a radiopharmaceutical by an organ or tissue indicating function / activity
activity
the number of radioactive decays per second measured in becquerels or curies
emission
release of energy or particles e.g. gamma rays, from a radioactive substance
scintigraphy
process of creating images using gamma camera to detect radiation emitted by radiopharmaceutical
hot spot / cold spot
hot spot- area of increased uptake of the radiopharmacetucal, indicating higher activity
cold spot- area with reduced uptake, indicating low activity or damage
contamination
unintended spread of radioactive materials on surfaces, equipment or personnel.
isotopes
atoms of the same element with the same no. of protons but different number of neutrons. this means same atomic number but different atomic masses
stable v unstable isotopes: basis for radioactivity
stable nuclei- balanced protons and neutrons
unstable nuclei- imbalance between protons and neutrons which causes instability
atoms with unstable nuclei release more radiation to achieve stability
radioactive decay-
radioactive atom becomes more stable by releasing particles and energy- this is called radioactive decay
-nuclei become stable through different radioactive decay as charged particles or photons
types of radiation - alpha
-2 protons and 2 neutrons- has no electrons
-relatively large, can’t penetrate very far into other materials
-strongly ionising: easily knock electrons off any atoms they collide with
types of radiation- beta
electrons- charge of -1 and has no mass
moderatley ionising as it is small- 5mm of aluminium
types of radiation: gamma
-waves of electromagnetic radiation
-no mass or charge- can pass through materials
-weakly ionising, can travel long distances and can be stopped by thick sheets of lead
-emitted from a nucleus
half life
time it takes for activity of the source to fall to half its original value
-short half life- (Tc-99m) ideal for imaging as there’s minimal patient exposure
-longer half life- (I-131) suitable for therapeutic purposes
e.g. tc-99m, 6 hour half life
after 6 hours, 50% of the isotope remains, after 12 hours only 25% remains
how are isotopes produced
-cyclotron- machine that accelerates charged particles using magnetic fields. creates isotopes like fluorine-18 which has a very short half life. requiring quick use after production, and is often located near hospitals to minimise decay during transport.
nuclear reactor- produces isotopes e.g. molybdenum-99, parent isotope for Tc-99m . exposes suitable target material to the intense reactor neutron flux for an appropriate time
generator
generator: portable system that extracts Tc-99m daily from parent MO-99 (parent)- separates decay product from the source radionuclide.
why are generators often used to create isotopes?
portable and easy to use in hospitals
provides fresh tc-99m daily for imaging.
radiolabelling
process of attaching a radioisotope to a carrier molecule to create a radiopharmaceutical., e.g. Tc-99m binds to phosphates naturally accumulating in bones so this is ideal for bone scans.
radioactive compound -> linker -> targeting molecule -> target protein -> cancer cell
what are the key functions of radiopharmaceutical preparation:
this takes place in a specialised hot lane, equipped with shielding and designed for safe handling and storage of radioactive materials.
key functions:
-radiopharmaceutical preparation
-quality control testing (radiochemical purity)
-dose measurement
what are the essential tools used when preparing radiopharmaceutical d
-lead glass window: protects staff
-vial shelf and tongs to handle sources
-shielded containers and syringes: limits exposure when handling. also used for prep and administration of radiopharmaceuticals
how is radiopharmaceutical dose calculated?
accurate dosing- calculated based on patients weight, height, medical needs and scan type.
preparation of administration
- safe transport and handling: using shielded containers to transport radiopharmaceutical
-administration to patient: injection or oral, depending on scan requirements
-imaging procedure: immediate or delayed imaging based on radiopharmaceutical and scan type.
what does SPECT stand for?
single photon emission computed tomography
what is the definition of spect
-single photon:
-emission imaging:
-computed:
tomography:
single photon: detects single gamma photons that are emitted from a. tracer in the body, unlike chest XRs which just pass through
emission imaging: detects radiation emitted from the body
computed: algorithms to reconstruct images using multiple angles and enhancing details
tomography: creates 3d cross sectional images to enable precise tracer localisation
