introduction to diagnostic imaging Flashcards
when was the X ray invented and by who
1985
Wilhelm Conrad Rontgen
when was the CT (computed tomography) invented and by who
1978
Sir Godfrey Hounsfield
when was the MRI invented and by who
1933
Sir Peter Mansfield
diagnostic imaging
use images to make a diagnosis
interventional radiology
image guided surgery
radiotherapy
high energy radiation - kill cancer
radiologist
dr specialising in interpretation of medical imaging
radiographer
technician
takes images
2 types of diagnostic imaging with ionising radiation
X ray and CT
Nuclear medicine - give radioisotopes and measure the radiation that comes out of them
diagnostic imaging without ionising radiation
ultrasound
MRI
issue with ionising radiation
small dose of cancer causeing substances - cause cancer in subsequent years
effect of ionising radiation with age
when younger, tehre is a higher incidence of developing cancer
but need to look at the risk benefit ratio
describe x-rays
tissue type affect attenuation of the x-rays
pass through low density air and fat - black (fat less black than air)
50% through soft tissue - grey
few through bone - white
metal/contrast agent -really white
why are lungs black on x ray
full of air
what would you see if there was a pneumonia in an x-ray
white because pus
in the thorax what cant an x ray distinguish between
heart muscle,
pericardium,
blood inside the heart
what could a white spot on an abdominal radiograph suggest
l sided kidney stone
what is used to improve radiography quality
contrast:
barium and iodine both very white
barium introduced by swallowing, enema?
iodine into artery or vein
describe CT
use X ray
tube spins
detector spins on opposite side
computer performs calculations to produce cross sectional map of tissue density
what can CT differentiate between that x ray cant
water and soft tissue
what is it called when CTs are expressed in different ways
CT windows
what are CT reconstructions
you can display them in any plane that you want to
allow you to see different things without scanning the patient again
describe the different planes
sagittal - down spine
axial - transverse, cut woman in half
coronal - like surgeons see
describe contrast in CTs
iodine injected into an arm vein
enhances the bv
differentiate pathological from normal tissue
risks:
allergic reaction to iodine
if have kidney damage the iodine will make it worse
what does a PE look like on a CT
black hole
what do tumours look like on a CT
black hole
need contrast though because the density difference is nit enough for a normal CT
describe ultrasound
uses high frequency sound to make images - reflect of the tissue
made and detected by a transducer - speaker and microphone
2D image
no radiation hazard - completely safe
describe MRI
magnetism and radiofrequency waves
strong magnet - supercoiled with helium.
protons in bldy line up in 1 direction
transmit radiowave pulses - cause different degrees of spin, they relax in a different way
listen for radiowaves caused by the interaction with protons in the patients body
different tissues give different intensities fo returned waves
bone colour on CT and MRI T1 and T2
CT - white
MRI- black
bone marrow colour on CT and MRI T1 and T2
Ct - grey
MRI - white
soft tissue on CT and MRI T1 and T2
grey
MRI more variable
fluid on CT and MRI T1 and T2
ct - dark grey
MRI t1 - black
MRI t2 - white
fat on CT and MRI T1 and T2
CT black
MRI white
air on CT and MRI T1 and T2
black
describe nuclear medicine
radioactive tracers that emit radiation - give isotope that is taken up by the tissue
different tracers go to different organs or parts of the body
images made by detecting the radiation by a gamma camera
normal bone scan with nuclear medicine
even uptake of bone trace
damaged bone scan with nuclear medicine
try to repair bone so more uptake in the damaged area - eg because of cancer
what do you see in a normal lung scan
ventelation and perfusion are the same
what do you see in lungs with a clot in a scan
ventilation normal but area missing off perfusion scan
describe positron emission tomography
detect metabolic or functional changes
effective in diagnosis of cancer and staging of cancer and if it is respinding to cancer
why do you combine pet and Ct
better anatomical location of cancer
faster and more specific than PET alone
terms that mean back
posterior
dorsal
terms that mean front
anterior
ventral
term that means closer to the edge
lateral
term that mans closer to the centre
medial
term that means towards the head
cranial
term that means towards the tail
caudal
when are dorsal and ventral used more
in embryology
what is the term for the top of the feet
dorsal
what is the term for the sole of the feet
plantar
term for palm of hand
palmar/volar
term for bottom of hand
dorsal
term for furthest away
distal
term for closest
proximal
why can you see the bowel clearly in an xray
gas v different density to soft tissue
benefits of CT
can make a 3D image
can inflate the colon with air and prevent the patient having to have a colonoscopy
