Imaging In Inflammatory Disorders and Infection Flashcards Preview

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Flashcards in Imaging In Inflammatory Disorders and Infection Deck (21):

What is a PET used to view?

Metabolic processes in the body


What is another name given to the tracer that is introduced into the body on a biologically active molecule?

A positron-emitting radionuclide


How is the 3-D image created?

Detected gamma rays are used to determine tracer concentration within the body, this is then used in computer analysis to construct the 3D image.


Why is the biological molecule used in a PET scan an analogue of glucose, for example fludeoxyglucose?

The concentrations of tracer will indicate the metabolic activity as it will correspond to the regional glucose uptake


What is the most common use of the PET scan?

To explore the possibility of cancer metastasis


What can PET also be used for?

Clinical diagnosis of certain diffuse brain diseases such as those causing various types of dementia.

Important research tool to find map out the normal human brain and heart function.


What is the best detector for PET imaging?

PET scanner, however dual headed conventional gamma camera can be used, quality of image is however much lower


Why does a patient have to wait after ingesting the radioactive tracer or isotope?

To allow time for the active molecule to become concentrated in the tissue of interest.


What does the radioisotope in a PET scan emit?

A positron, antiparticle of electron with opposite charge


What happens to the emitted positrons?

They decelerate until they are able to interact with electrons, at this encounter both the electron and the positron are annihilated producing a pair annihilation photons moving in approximately opposite directions. These are detected in the scanning device.


How do gamma rays occur?

The radioactive decay of unstable isotopes


What are the properties of an ideal isotope used in radiography?

Half-life similar to length of examination.

Gamma emmiter

Energy of rays between 50-300 keV

Radionuclide should be readily available at hospital site

Easily bound to pharmaceutical component

Radiopharmecutical should be easy to prepare


What type of radiation does a radionuclide emit?

Gamma radiation


What makes the picture in a PET scan?

Gamma rays are created during the emission of positrons and the scanner then detects the gamma rays. An image of the map or organ is then created by computer analysis of the data collected by the scanner.


What is often combined with PET? And Why?

CT scans, provides a more definitive information about malignant tumours and other lesions


What does SPECT stand for?

Single photon emission computed tomography.


What is the difference between PET scans and SPECT?

The type of radio tracers used, SPECT radioisotopes emit gamma radiation.


What is the estimated effective radiation of a PET scan?

25 mSv


What is the effective dose or a radiography chest?

0.1 mSv


What is the effective dose of CT chest?



How is imaging used with relation to inflammatory and infectious conditions?

Used in diagnosis and monitoring of treatment