AP07 - medical imaging Flashcards
How are X-rays produced?
a tungsten anode is bombarded with electrons under high voltage, releasing radiation
How might soft-tissues be examined using X-rays?
using a water soluble contrast medium (normally barium or iodine based materials)
What is an X-ray angiogram used to make?
ateriograms and venograms
How might vessels be viewed on an X-ray?
Computer elimination of non-contrast-containing surrounding tissue
What effect limits visibility of organs in the thorax during X-ray?
the shadowing effect
What is the main drawback to CT
It can’t diferenciate between tissues of the same density (you’d see nothing in the brain as grey and white matter have the same density)
How would you study the chest using a CT scan?
using a contrast media
How are ultrasound waves generated?
using piezoelectric crystals in a transducer
What 2 effects determine the image produced in Ultrasound?
Attenuation (loss of energy from the system)
reflection
What is used to study moving substances in Ultrasound?
The doppler effect
What does an MRI actually meaure?
The energy released when the planes of protons in water return to their original orientation after being flipped by another magnetic field
What is fMRI, what is it used for?
Contrast is put into the blood and detects where the oxygen in the blood is being used, reflecting metabolic activity
What are PET scans used for?
uses a short half-life chemical in the blood stream which emits gamma radiation, used for viewing cancers of high metabolic activity.
What two techniques could be combined to see brain funciton?
fMRI and PET
How are the trachea/bronchi viewed?
broncoscopy (endoscopy)
