quiz 1 Flashcards
what does PACS stand for?
picture archiving communications storage
what types of images can be stored through PACS?
- xray
- CT
- MRI
- US
- fluoroscopy
- nuclear medicine
advantages to x-rays
- inexpensive
- commonly used
- can be obtained almost anywhere via portable devices
disadvantages to x-rays
- uses ionizing radiation
- limited to 5 basic densities
5 basic densities
- air
- fat
- soft tissue/fluid
- calcium
- metal
air on an x-ray
- absorbs least amount of x-rays
- appears blackest
fat on an x-ray
- gray
- slightly darker than soft tissue
soft tissue/fluid on an x-ray
- both have same density on films
- cannot tell the difference between the two
calcium
- most dense of naturally occurring materials
- absorbs the most x-ray
metal
absorbs all x-rays and appears whitest
requirements for production of x-rays
- source of electrons
- way to accelerate them
- way to stop them
- vacuum
x-rays are the initial imaging study of choice for what type of injury?
skeletal trauma
lateral x-ray position
- 90 degrees to AP or PA
- decubitus is recumbent to horizontal beam
lateral decubitus x-ray position
- used to see air/fluid levels
- side up shows air
- side down shows fluild
- good for abdominal problems
oblique x-ray view
- halfway between AP/PA and lateral view
- most extremity projections involve 3 views
x-ray projections
- path of central ray as it exits and goes through patient to image receptor
- AP/PA
- axial
- tangential
- lateral
- oblique
extremity pain with negative x-ray
- treat with splint
- f/u with ortho in 7-10 days
- repeat x-rays may show cortical changes
underpenetrated film
appears too white, no goo range of densities and have blurring of interfaces
overpenetrated film
appears too black, no good range of radiological densities and absence of interfaces
what is the most important part of musculoskeletal evals?
history
reading the x-ray
- viewed in anatomical position
- your left is pts right
- extremity work viewed fingers/toes up
- assess adequacy of image
- motion, magnification, distortion
- geometric vs photographic properties
geometric properties
- magnification- size
- distortion
- elongation- shape
- foreshortening- shape
shape distortion
- elongation occurs when tube or image receptor are improperly aligned
foreshortening
the further away from the plate an object is the bigger it looks
ABCS of reading the x-ray
- A- adequacy, alignment
- B- bones
- C- cartilage
- S- soft tissue
CT scan
- uses rapidly spinning arrays of x-rays and computer processing to increase sensitivity of findings visible
- cross-sectional imaging
- mod expensive
- uses much higher dose of ionizing radiation than x-ray
CT better than x-ray in:
- ident subtle fractures
- visualizing articular fx extension
- assessing presence of articular stop off/gap
ultrasound
- produces images using acoustic properties of tissues
- no ionizing radiation
- useful in eval of soft tissue and blood flow
- less expensive
- portable
MRI
- produces images based on energy derived from H atoms
- atoms placed in magnetic field and subjected to RF pulsing
benefits of MRI
- no ionizing radiation
- good for neuro and soft tissue
- helpful to dx occult fx
fluoroscopy
- utilizes ionizing radiation to produce real-time visual of body
- eval of motion, positioning, GI studies
- eval of fx for reduction and placement of pins/ hardware
- c arm support system
nuclear medicine
- utilizes radioisotopes that have been given property target
- pt is source of radiation
- used for metastases, occult/stress fx, insufficiency fx
5 radiographic opacities
- air
- fat
- soft tissue
- bone
- metal
CXR basics
- AP or PA view
- upright/ erect or supine
- rotation
- inspiration
- penetration
- all landmarks present
how to tell of CXR is rotated
should normally have equal distance between medial end of clavicle and midline of body
why inspiration is important for CXR
- when you inspire diaphragm goes down
- allows for better view of cavity
- should be able to see 10 ribs
CXR penetration
- appropriate- should barely see discs through heart
- over- clearly see discs
- under- don’t see discs at all
pitfalls to CXR interpretation
- poor inspiration -> squish effect
- over or under penetration
- rotation -> shadow summation effect
normal CXR cardiac structure
- central in younger infants and kids
- more on L in older infants and teens/adults
normal CXR cardiac size
- measure R boarder of heart to midline
- measure L boarder of heart to midline
- these two spaces should be less than the wides space at bottom of lungs
- greater than 50% of chest is abnormal