scans Flashcards
how do CT/CAT scans work
2D images are layered to represent 3D structures
what’re the advantages and disadvantages
A: shows internal structures
D:X-rays are harmful
only 2D images captured
how do MRI scans work
radiowaves and a magnetic field used to build a 3D image
advantages and disadvantages
A:shows internal structures in 3D, no radiation
D:3D still images, expensive, cant use with metal in the body
how do FMRI scans work
radiowaves and a magnetic field build a 3D image except used to track bloodflow to show areas of activity
advantages and disadvantages
again cant use with metal in the body and expensive
how do PET scans work?
radioactive tracer detected by a radiotracer
advantages and disadvantages
radioactive substances ingested
how’re CT scans more detailed than X-rays?
-CT scans show 3D imaging wheras x-rays only show 2D
-CT more detailed than X-rays as images taken from multiple diff angles
-CT scans take axial/cross sectional images and can reveal whole interior of the body, x-rays only provide aligned snapshots
howre images in CT scans generated
rotating the x-ray generator and detector around the patient
this info is fed into a computer which reconstructs images of the body structures
what are MRI scans particularly good at looking at
soft tissues (fat, cartilidge, muscle and the brain)
how do MRI scans work
-patient placed in strong magnet
-nucleus in each of their H atoms behaves like a magnet
-normally the H atoms are randomly arranged but in the magnetic field of the MRI scanner they line up with the magnetic field
explain step by step
-patient exposed to a burst of radio waves
-these cause all their hydrogen nuclei to line up with applied magnetic field
-radio waves turned off
-nuclei flip back to their origional position
-when they flip back to og position they give out radio waves
-a detector picks up the radio waves produced and a computer uses these to produce a 3D image
how does FMRI work
deoxyhaemoglobin absorbs radio waves
oxyhaemoglobin doesnt
in active areas of the brain there will be increased blood flow/oxyhaemoglobin to those areas
less radio waves absorbed in that area
will light up on FMRI images
how do PET scans work
patient takes a radiotracer which circulates in the blood
whilst in scanner patient carries out a task
region responisble for task has increased oxygen requirement
so more blood flow/ radiotracer to that area
computer picks up signal from radiotracer
MRI scans function advantages and disadvantages
-magnetic field , radiowaves released
-nuclei of H atoms in individual behave like a magnet line up with applied magnetic field
-normally wouldnt
-when magnetic field turned off H atom nuclei flip to og position radio waves are emmited
-detector picks up the radio waves produced and a computer uses these to produce a 3D image
A:soft tissues shown, 3D, no exposure to radiation
D:cant bring in metals, expensive
PET scans function, advantages & disadvantages (involves doing task)
-radiotracer injected into patient and theyre asked do do a task
-whilst doing task there will be high O requirement in areas of brain responsible for doing these tasks so increased blood flow/radiotracer to active areas of the brain
-computer picks up signal from radiotracer
A:can track blood flow, precise
D:exposure to radiation, expensive
FMRI scans function, advantages & disadvantages (doesnt involve doing task)
-same function as MRI
-deoxyhaomogloblin will absorb radio waves oxyhaemoglobin wont
-increased blood/oxyhaemoglobin flow to active areas of brain,
less radio waves will be emitted from these areas
-will light up on FMRI imaging
CT scans function, advantages & disadvantages
-x-rays sent from every direction/axial
-rotating x-ray generator and detector around patient
-info from detector processed by computer 3D representation of body structures produced from each image
-shows internal structures
A: 3D
D:x-rays are harmful, only 2D images generated
