Introduction to Imaging Flashcards
what is an x-ray
an electromagnetic packet of energy with a extremely short wavelength between 0.1 and 10 nanometres
The principles of x-ray generation and image capture
streams of x-rays
intensity of x-rays varies depending on tube current, atomic number of target, tube voltage
interactions with matter - scatter, transmission, absorption
Two luminescent screens sandwich the film emulsion
emulsion contains silver halide - clumps form after exposure to light generated on luminescent screens
Why do different anatomical structures have different appearances on x-ray imaging
Attenuation - the process by which radiation loses power as it travels through matter and interacts with it
increases with atomic number
increases with density
increases with thickness
bone or soft tissue has varying degrees of absorption which results in white image
Principles of CT
rotating x-rays tube
multiple beams
single axis of rotation
digital geometry processing… axial image
often give iodinate contrast - intravenous, oral
IV contrast can lead to kidney failure
great for defining dony detail
exposure to radiation
Principles of Ultrasound
non-ionising
sound waves
high frequency sound pulses 1-20MHz
at various levels in body ie. tissue you get an echo that bounces back to probe - various patterns
probe applied to skin over gel based lubricant - air doesn’t allow for transmission
Principles of fluoroscopy
medical imaging test that uses an X-ray beam that passes continuously through the body to create an image
used to obtain real-time moving images of the interior of an object
Scientific basis of the use of iodinated contrast media
Iodinated contrast media are contrast agents that contain iodine atoms
Contrast media are primarily used to visualize vessels and changes in tissues on radiography and CT
Hazards of ionising radiation
Ionising radiations can cause dermatitis, burns, cell damage, cataracts and changes to blood
