Imaging in Inflammatory Diseases and Infection Flashcards
What does molecular imaging consist of
Radionuclide imaging
Positron emission tomography
Magnetic resonance imaging
Optical imaging
How does radionuclide imaging occur
Gamma rays are beamed into the patient who transmits them back out
They go to the lead collimator gamma camera
What is radiography
X-rays being beamed through a x-ray tube to the patient to form a digital image capture
How do gamma rays occur
From the radioactive decay of unstable isotopes
State 3 features of gamma rays
High energy
High frequency (approx 10^20 waves per second)
Similar properties to x-rays
What are radiopharmaceuticals
Drugs with a:
Radioactive element
Pharmacetuical element
State 7 properties the ideal isotope should have
A half-life similar to the length of examination
Emmitt gamma instead of α or β
The energy of γ rays should be between 50-300 keV
The radionuclide should be readily available at the hospital site
Should be easily bound to a pharmaceutical component
The radiopharmaceutical should be simple to prepare
The radiopharmaceutical should be eliminated in a similar half-time to the duration of the examination
Give 4 examples of ideal isotopes
Hydroxy-diphosphonate for the bone
Dimercapto-succinic acid for the kidney
Hexamethyl-propine amine oxime for the brain
Macroaggregated albumin for the lung
How does a gamma camera produce an image
Nuclear energy will be released from inside the radioactive nucleus
Gamma ray emitted from the patient known as gamma electromagnetic energy
Image crystal (NaI) produces flashes of light known as light electromagnetic energy
This is converted into electrical energy to display the image.
What does SPECT stand for
Single photon emission computed tomography
What is the image quality of the gamma camera dependent on
Radiation dose (limits are in place)
Collimator
Metal objects
Proximity of area of interest to camera
What is SPECT
A CT version of nuclear medicine where the gamma camera rotates around the area of interest
What is SPECT mainly used for
Brain and cardiac studies
But can be applied to any site of interest in other studies
Gives examples of other studies SPECT can be used for
Spine in bone scan
Lung scintigraphy
What does PET stand for
Positron emission tomography
What is PET
A form of molecular imaging which uses radionuclides that decay by positron
What is PET used for
Produce images of biologically interesting processes
For absolute quantitation
State a negative feature of PET
Requires arterial sampling
How is a PET image produced
Positron emission releases gamma rays which are detected by a detector in the imaging ring and enter the coincidence circuit to produce an image
Name 4 PET radionuclides and their half lives
18^F - 110 minutes
11^C - 20 minutes
13^N - 10 minutes
15^O - 2 minutes
What does 18^fluorodeoxy glucose (FDG) do
It takes the place of glucose to produce 18^FDG-6-P
Where is FDG taken up physiologically
Brain Myocardium Stomach Liver Spleen Colon Urinary tract
What are the risks of radiation
Ionising radiation
Inducing fatal cancer
Cost
Risk to patients and staff
What are the benefits of radiation
Diagnosis of disease
Management change
Treatment
