RADIOLOGY Flashcards
what is an xray
form of electromagnetic energy with a very short wavelength which allows xrays to penetrate matter unlike light rays
How are xrays produced ?
xray tube consits of an evacuated glass tube with cathode and anode terminals; cathode tungsten filament in heated to incandescencce, giving off electron; electrons bombard positively charged anode target and xray are emitted
ionizing radiation
radiation that has enough energy to remove electrons from atoms or molecules; forms of ionization radiation include Xray, gamma rays, alpha particles, beta particles and neutrons
what involves ionizing radiation
xrays, nucleur medicne studis and fluroscopy
radioopaque tissue is
denser, absorbs more xrays and appears as white image on film
radiolucen tissue is
less dense, absorbs less xrays and appears as darker image on film
film cassette
patients cannot hold still long enough to obtain an image from x rays along; cassette contains flourescent screens which glow when activated by xrays and this light is used to expose the film; less radiation and exposure times are needed; the grid cuts down on scatter effect on film-like a lens
The close an object is to the film
the less magnified its image
advantages to digial radioagrphy
less storage space
multiple monitors can look at same image at the same time, difficult to Lose films, transmitted electronically, view generated can be altered by the computer
disadvantages of digital radiography
hospitals arealdy have fully functional film based imaging equipment, new equpment is expensive, may not be as sharp
flouroscopy
common radiological technique allows realtime visulaization; continous beam of xrays; common procedures used for are upper gi and lower gi, and many interventional procedures
types of GI contrast
barium sulfate or iodinated water; not absorbed
barium sulfate
dense, good images, slow to be excreted, not good is body cavity is posibile, must be dilute for CT scan
iodine based water soluble contrast
ok if spilled into cavities, less dense, less details, toxic to lung tissue,
intravenous contrast
imaging of blood vessels or urinary tract use iodinated compounds but they are toxic to kidneys
ultrasound
narrow beam of high frequency sound waves is procued by vibrating crystals; sound waves directed into the body and reflected back dependent upon tissues differing acoustic impedance
anechoic
echo-free due to absence of acoustic interfaces
sonolucent
cyst or fluid filled viscus shows as dark area
echogenic
based on internal echoes due to acoustic interfaces, solid tisues, tumors, fat or fibrous itssue show as LIGHT areas
advantages of ultrasound
no ionixing radiation safe, multiplanar imaging; ability to differentiate cystic, solid and complex tissue, cost effectv, portable and realtime analysis
disadvantages of ultrasound
air and bone produce extreme impendance; most sound is reflected prohibitng sound penetration; images not as clear as CT or MRI, and operator depedent
doppler ultrasound
can be used to calculate velocity of moving blod
computer tomography
cross sectional xray imaging
in computer tomography dense tissues are
white
in computer tomography lease dense tissues are
black
advantages of CT scanning
extremely sensitive to slight differenences in tissue, comparison screen or film radiography requires 5% difference, excellent images, available almost everywhere
disadvatnages of CT scann
expensive, high demand may mean long wait time, ionizing radiation, over utilized
IV contrast for CT
differentiate vascular form nonascular structures, and urinary tract
oral contrast for CT
delineates GI tract, must NOT be TOO DENSE
MRI
imaging of protons
lungs are what color in MRI
black
fat under skin in MRI is
white
image in MRI are determined by
number of hydrogen atoms not by tissue density
gandolinium contrast
magnetically active and used to enhance contrast between tissues especially T1, blood stream, helps with imaging strokes, tumors, infections
disadvantages
long scanning times, claustrophobia people with pacemakers, non-ferrous metals interefere with image quality, high cost
bone in CT appears
white
bone in MRI appears
black
CT is excelletn for
bone
MRI is excellent for
soft tissue
common indications for CT imaging
trauam, intracranial hemorrhage, fracture detetion, evaluation, spine alignment, foreign bodies in joints, neoplasm,s axial images
uses for MRI
non urgen imaging, musculoskeletal system injuries
radioisitope scanning
radioactive isotope is given intravenously or by mouth and uptake is imaged with gamma camera
heptobiliary iminodiacetic acid or HIDA scan
injected, excreted by the liver into a biliary tree, enters the GB and flows into the bowel
sentinel lymph node scan
used in malignant melanoma and breast cancer cases; allows removal fo the first lymph node that drains the tumor site
SPECT
specialized gamma camera rotates around patient to produce a tomographic image used in cardiac imaging and cerebral perfusion scans
PET Scan
evaluates how cells use glucose FDG is given to patient and it concentrates in the tissue accroding to METABOLIC rate
PET is used for
oncology, cardiology, neurology
what are the three cervical spine series
AP, lateral and odontoid view
what can you see in a AP cspine
normal degenerative changes, articular pillar changes, alignment of lateral masses and perhaps any cervical ribs
what is the highest visulaized vertebrae in C spine AP view
c3
lateral C spine what do you need to see
must see all 7 cervical and top of t1 used for prevertebral soft tissue analysis
lateral C spine you can use to see
alingment of vertebral segments, high of vertebral bodies and height of intervertebral dics
odontoid view
see the integrity of dens and the alignment of C1 and C2
what does the presence of lipping of vertebral bodies indicate
presence of osteophytes
AP lumboscral spine
count vertebral bodies, check alignment, evaluate bone density, pedicles cortices, transverse processes, examine sacrm and SI joints
spondyloisthesis
anterior slippage of vertebral segment; fracture or defect in the pars interarticularis, visslbe displacement on lateral view
T1 MRI images
excellent resolution used to procure anatomic information
T2 images
better contrast cause water to light up and shows pathology well
colors of things in T1 image
fat is white, soft tissue is grey
in a t2 image what are the colors of things
water is ligher grey, fat greyl used to look for pathology
cortical bone, calcium, air and fast flowing blood
all appear very dark in MRI
what is the test of choice for chornic conditions
MRI
what is the test of choice for acute conditions
CT
what type of scan is helpful in deciding whether or not surgery is necessary for fractures of vertebrae
CT
what are the different types of fractures
segmental comminuted (pieces) spiral oblqiue transverse
communuted fracture
broken into several pieces or crushed
high probability of damage to surrouding tissues
may heal with immobilization but frequenly requires ORIF
oblque fracture
likely due to shearing force along line of fracture, pointed ends make open fractures morel ikely
spiral fracture
result of fixed distal component with rotational force
greenstick farctures
pediatric fracture, bone is flexed breakage is only on one side
torus or buckle facture
bone id flexed not completely transected, comparable to folding a papertowel roll
95% of glenohumeral dislocations are
anterior and subcoracoid
what is the best technique for rotator cuff injuries
MRI
what is sail sign associated with
radial head fracture, MRI can confirm diagnosis
Smith’s fracture
caused by falling on palmar flexed hand, reverse of colles fracture, distal radius fracture with palmar angulation of distal fragment
Colles fracture
caused by falling on dorsiflexed hand, distal radius fracture with dorsal angulation of distal fracment
perilunate dislocation
lunate is normal but rest of carpal bones dislocated posteirorly
lunate dislocation
lunate is rotated and dislocated toward palmar side
thickening around joints is called
herberdens nodes
ulnar deviation of digits is associated with
rheumatoid arthirits
MRI is test of choice for
medial meniscus tear
Mortise view of ankle
allows visualization of the relationship betweeen the distal tibia and fibula
