Nuclear medicine 1 Flashcards
what is tomography
slices that can be obtained
what kind of rays are used
gamma rays
what does PET stand for
positron-emission tomography
why do we use gamma rays
- not absorbed in patient
- high energy
how much KeV does technetium 99m produce
140 KeV
how much KeV dos PET use
511 KeV
where does radiation come from
radioactive tracers that have been injected into the patient (radioactive isotopes)
what happens when tracer is injected
- radiation is emitted continuously
- gradually decreases depending on half life
functional applications of radionuclide imaging
- shoes metabolic process and disease changes
- nuclear med can identify changes in disease/ recurrence of disease after treatment
practical applications of radionuclide imaging
- brain (stroke/ alzheimer’s)
- oncology (metastasis/ cancers)
- renal function
- cardiac heart muscle function/ infarction
- pulmonary embolism
what makes a radioisotope
increased number of neutrons will make nucleus unstable
how does a nucleus regain stability
emits gamma rays
what is ejected during alpha decay
- 2 neutrons
- 2 protons
(helium)
what is isomeric transition
can occur through internal conversion
- nucleus is an excited state and undergoes transition to a lower-energy isomeric state by emitting gamma ray protons
what is electron capture
orbital electron captured by nucleus and combines with proton to form a neutron
what is a neutron called after an electron combines with a proton
neutrino
what happens when electron combines with proton
neutrino emitted from nucleus and carries away some energy
- remaining energy appears in form of x-rays
advantages of radionuclide imaging
- tracers give functional information about physiology molecular transport
- relatively easy to give in small volumes
- can merge functional images with anatomical ones
hybrid imaging
functional images merged with anatomical ones
3 broad classes of scanner
- planar RNI - 2D images using single gamma camera
- SPECT - sectional 3D RNI
- PET
what does SPECT stand for
single photon emission imaging
problems associated with gamma rays
- tend to pass through things
- cant focus
- also emitted in nature
- ionising radiation cause radiation dose
what are modern gamma cameras
detect gamma rays emitted by radioactive tracers within body allowing for visualisation of organ function and identification of abnormalitiesw
what do modern gamma cameras use
cadmium zinc telluride (CZT)
- solid state detectors offer improved energy resolution and sensitivity compared to traditional scintillation crystals
what kind of tracer does bone scan use and why
Tc-99m has a strong affinity for bone tissue
- phosphate
process of bone scanning
- inject phosphate based tracer
- 2-4 hours wait
- image
- table moves between camera heads
- software removes blurring
- 20 minutes
