Radiology Flashcards
What is contrast media?
Bring out diff tissue against normal tissue = helps diff tissues
What imaging techniques use contrast media?
CT, MRI, arteriograms, US, fluoroscopy
What 2 groups can contrast media be broken into?
Positive: see it as white – barium, iodine, gadolinium.
Negative: see it as black – water air CO2
What are the ideal characteristics a contrast media has to have?
Low osmolality and viscosity, high water solubility, biologically inert = safe, heat and chemically stable, cost effective
How can contrast media be administered?
Oral, rectal, IV, filling space/cavity
Where is contrast media mainly excreted?
Kidneys = glomerular filtration 95%
What is the difference between an idiosyncratic and non-idiosyncratic reaction?
Idiosyncratic: within 20 mins.
Non-idiosyncratic: after 30 mins
What happens to an x-ray beam that causes magnification?
As the beam travels to the sample it widens
What are the CT/MRI imaging planes?
Axial, coronal, sagittal, oblique
In terms of terminology what is the difference between cranial and caudal?
Cranial: towards the head.
Caudal: towards the feet
How can the 2 biological effects of radiation be classed?
Deterministic: threshold of no effect, steep rise after threshold.
Stochastic: risk directly proportional to dose
How do we measure radiation?
R: radioactivity = amount of ionising radiation released.
E: exposure = amount traveling through air.
A: absorbed dose (unit = Gray Gy).
D: dose equivalent = combines amount absorbed and medical effects (unit = Sievert Sv).
Regarding radiation what does ALARA stand for?
As low as reasonably achievable
Outline some MRI contraindications?
Cardiac pacemaker, implanted/external medical pump, cochlear implant catheter with metallic components
