Imaging Flashcards
what factors are considered with radiation?
quantity & energy
radiolucent appears ____
dark
radiopaque appears ___
light
what is the most radiolucent material
air
what is the most radiopaque material
metal
position
actual position of the patient (seated, supine, etc)
projection
path of central ray from the perspective of the tube (in anatomical terms, e.g. anteroposterior)
a projection must be named with what
2 surfaces
view
body part from the perspecitve of the image receptor (always opposite of projection. if projection is AP, view is PA)
method
description of position & projection
positioning principles
- pt assessment
- goals of exam
- equipment
- protocol vs ergonomics
- body habitus (size, wt)
ergonomics
what the pt can actually do
rules (4)
- always 2 views, 90deg from ea other (usually PA or AP + lateral).
- complex jts may need 3 views (usually PA/AP, lateral, + oblique).
- always include both ends of long bone.
- include entire prosthesis/fixation.
ring of bone fx pattern
a single bone or set of bones arranged in a circle cannot be broken in only one place
positive contrast media
adding density to the part (either Iodine or Barium).
negative contrast media
taking away density
purpose of contrast media
to demonstrate adjacent anatomical structures that normally have similar tissue densities.
Radiopaque Contrast Materials
increase density of a structure so more x-rays are absorbed before reaching the radiographic film; makes a whiter area on the radiograph
Radiolucent Contrast Materials
decrease density of a structure so that fewer x-rays are absorbed before reaching the radiographic film; makes a darker area on the radiograph
conventional tomography
Time-consuming, higher radiation exposure, good for spine, joints, tumor matrix. If pt moves, have to completely start over. The “older” CT. Once CT became a thing, this lost popularity.
computed tomography
Greater expense and radiation exposure, higher tissue contrast.
Lower spatial resolution (does not show certain things).
Planar reformatting/3D display: can move it around to see a bunch of angles.
Limited scanning planes (pt has to fit inside)
MRI: what needs to be considered?
metals: can shift around from magnets. surgical steel not affected, but it will screw up the image
color on MRI
does not follow the rules from x-rays
what shows up well on MRI
high water content
nuclear medicine uses what chemical compound
Diphosphonate
nuclear medicine has ___ specificty & ____ sensitivtiy
low speciificity
high sensitviity
nuclear medicine is good for what
stress fx
PET (Positron Emission Tomography) good for what
oncology
PET uses what chem compound
fluorine 18
consideratiions w/ PET
half life of minutes
PET has ___ sensitivity
high
what other scan is commonly combined w/ PET
CT
ultrasound good for what
fluid spaces, pediatric hip disorders (especially good for kids bc no radiation)
what are streaks on ultrasound
air
BOLTS
Breaks or steps in the cortex. Opacities (impacted fx - lighter). Lucencies (displaced fx - darker). Trabecula disruption. Soft tissue swelling.
how to describe fx
Location
Description (comminuted, compression, oblique, transverse fx).
Displacement of distal fragments
Angulation. of distal fragments
Distraction/overlapping
Involvement of epiphysis, physis, metaphysis
how to describe displacement/angulation on lateral scans
anterior or posterior
how to describe displacement/angulation on AP scans
medial or lateral
angle can also be described as varus/valgus
salter harris types
fill in later
