Week 3.2 CT Scan Flashcards
what are all the names of a CT scan
CT, CAT Scan, computerized tomography, computed axial tomography, computer aided tomography
what is a CT scan
a combo of multiple images generated by ionizing radiation
with cross sectional slices, up. to 1,000 projections, and computer generated 3D views
getting a CT scan is like getting…
1000 x-rays of the same body part
what is the CT process
the patient is positioned on the gantry, or the bed, and the spiral CT has a source and an opposing detector array that rotate around the tube to give you multiple slices.
how thick are the slices
1/2 mm thick, and all at 90 degrees slices.
how does an X-ray differ from a single slice of CT from a whole CT
the x-ray can show fractures, but the single slice only shows what is in that slice, and nothing anterior or posterior to it. The 3D can show bone fragments and little pieces.
what are CT with contrast
generally replaced with MRI, but these are CT arthrogram, CT myelopgram
orthopedically, how is a CT with contrast done
you infect the contrast, and take an x-ray or fluoroscopic image to confirm its placement, then you take the CT
what might a CT with contrast be good for
GI, vascular, renal studies, or you may do it for obese and claustrophobic, pacemakers, or magnetic metal implants too
when might the CT with contrast be done over an MRI
patient to large for scanner MRI
claustrophobia,
impacted pacemaker or metal device
CT advantages
evaluates osseous structures well
evaluates soft tissues moderately well
evaluates cortical bone better than MRI lower exposer and less time
what things is it a modality of choice for
subtle or complex fractures degenerative changes in the joint serious trauma spinal stenosis loose bodies in the joint measurement of osseous alignment
what is the risk of CT
radiation exposure that is higher with contrast
what is the limitation of a CT scan
histological makeup, based on radio density.
a tumor may look the same as muscle surrounding it if there is similar or same density. CT can miss things that are similar density
TF: a CT has way more exposure to radiation than a radiographs
true
