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Imaging Lecture Test 4


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What are four special concerns w/ equine radiography?
proper restraint, possible injury to personnel, damage to machine, need more time & patience
Name two positioning devices for equine radiography
positioning block and cassette tunnel
What is the most common type of xray machine for equine?
What is the most common cassette size for equine xray?
What are three machine options for equine xray?
small portable, mobile unit, mounted unit on rails
Four safety considerations for equine xray?
protect personnel 1st (equip 2nd), take safest view possible, avoid views from behind rear leg, never hold xray tube
Why is labeling esp important for equine xray?
all legs look the same from cannon bone distally
3 technique consideration for equine xray?
clean debris from area of interest, pick foot & pack w/ playdough, and views of joints should be done weight bearing
Why are special contrast techniques needed?
give more info than flat films, used to highlight a lesion, increases contrast w/i a specific organ
What are two types of contrast media?
pos and neg
What type of contrast media makes area white?
What type of contrast media makes area black?
Give 2 examples of positive contrast medias
Organic Iodine & Barium
What contrast media is used for excretory urography, angiography, and cystography?
Organic Iodine
What contrast media is usually used for the GI tract? When would it not be used and what would be used in its place?
Usually barium, but contraindicated if perforation suspected - then iodine would be used
Examples of neg contrast medias
room air, oxygen, CO2, nitrous oxide
What 2 neg contrast medias are safer because they are easily absorbed and have lest chance of air emboli?
CO2 and nitrous oxide
What type of contrast media is used for pneumocystography, double contrast studies, and pneumography?
What contrast media has side effect or air embolism?
What are some side effects of iodine?
nausea, allergic reaction, anaphylactic reaction, hypotension, and shock
What are some side effects of barium?
aspiration (make sure tube is in stomach), peritonitis (from perforation - leaks into abdomen)
What change of exposure technique is used w/ contrast media?
Increase MAS by 30%
Describe general patient prep for abdominal study & what views taken?
fast for 12-24 hours if possible, enema 4 hours prior, VD and right lateral views taken
When is excretory urography indicated?
to check kidney function and size
What is procedure for excretory urography?
place indwelling IV catheter, give bolus injection of iodine contrast agent, take films
What are the 3 phases of excretory urography?
nephogram (see renal vasculature), pyelogram (see renal pelvis), drainage phase (see ureters)
When is cystography indicated?
to examine bladder wall for abnormalities or tears
What are 2 precautions for cystography?
don't over fill bladder - it can rupture, use nitrous rather than air because of air embolism
What is the procedure for cystogram?
sedation necessary, do survey films first, clean penis, pass urinary catheter, remove urine, infuse contrast agent until bladder is moderately full
Name and describe 3 kinds of cystograms
pos contrast (iodine), pneumocystogram (gas), double contrast (both)
When is a urethrogram indicated?
to examine internal structure of urethra
Name the 2 types of urethrograms
retrograde and antegrade
describe a retrograde urethrogram
+ or - contrast inserted w/ a balloon-tipped catheter, film taken at end of injection
Describe retrograde urethrogram
+ contrast is placed into bladder (must use enough to induce urination), film is taken at voiding
When is esophagography indicated?
to examine esophageal function
Describe esophagography procedure
barium or iodine used, pt. in lateral recumbency slowly infuse contrast agent into cheek or mix into food, take film at pt swallows
When is an upper GI study indicated?
to evaluate stomach and small intestine
In what situations are barium and iodine not used in an upper GI?
don't use iodine in a dehydrated pt, don't use barium if perforation is suspected
Describe patient prep for an upper GI?
21-24 hr fast, enema 4 hours prior, sedation if needed
Describe procedure for upper GI
do survey film first, use barium or iodine, place stomach tube, induce agent into stomach
What views are taken in an upper GI series?
VD, DV, & rt lateral
Describe a double contrast gastrogram
same as upper GI except pt needs empty stomach and gas introduced right after barium - films done right away (don't wait)
When is a barium enema contraindicated?
when rupture/perforation is suspected
Describe procedure for a barium enema
survey films first, pt in lateral recumbency, lubricated enema cath inserted and balloon inflated, infuse media slowly
What is a pneumoperitonealgram
the injection of CO2 or nitrous into the peritoneal cavity to improve the contrast of abdominal organs
What is a myelogram?
induction of iodine contrast into the subarachnid space around the spinal cord
What is a non-selective angiogram?
injection of a bolous of iodine contrast into a vessel - film is taken at time of injection and is effective for identifying occulsions or aneurisms
How does US work?
Short bursts of ultra-high frequency sound waves are xmitted into patient. When they hit something they bounce back and are converted into a white dot on monitor screen.
In US, the greater the difference in density and composition between two adjoining tissues, the ____ the echo will be.
In US, the stronger the echo, the ____ the white dot on the monitor screen.
In US, what determines the position of the white dot on the monitor screen?
the length of time between the production of the sound burst and the return of the echo
In US, echos from deeper tissues take ____ to return to the transducer and will be be placed as white dots ____ on the monitor screen.
longer, lower
In US, echos from more superficial structures tissues return ____to the transducer and will be be placed as white dots ____ on the monitor screen.
faster, closer to the top
What is the appearance of fluid on an US?
What is the appearance of soft tissue on an US?
shades of grey
What is the appearance of bone/stone/gas on an US?
What is acoustic impendance?
How well a substance xmits sound
What is acoustic interface?
the boundary between two tissues w/ different xmitting properties (causes returning echo)
What is echogenicity?
the ability to produce echos
What is anechoic?
produces no echos (no dots on screen)
What is hypoechoic?
Produces weak echoes (grey dots on screen)
What is isoechoic?
produces echoes similar to background echoes
What is hyperechoic?
produces intense echoes (bright white dots on screen - bones)
What is resolution?
The degree of image detail and quality
One cycle per second is called a ____.
One million cycles/second is called a ____.
Diagnostic US uses sound waves at what frequency?
2-10 MHz (2-10 million cycles/second)
What is attenuation?
sound waves are attenuated or decreased as the travel through tissue
What three thing can cause attenuation?
absorption, reflection, and scatter
What are three common transducer frequencies?
3.5, 5, and 7.5 MHz
The higher the transducer frequency, the ____ the sound wave is attenuated, but the ____ the detail.
faster, better
lower transducer frequency = ____ penetration and thus ____ poorer resolution
better penetration, poorer resolution
higher transducer frequency = ____ penetration and thus ____ poorer resolution
lower penetration, better resolution
US does not penetrate what three things?
bones, stones, and air
In US, you must have gel between transducer and skin in order to eliminate what?
air gap
What is an acoustic window?
clear path for sound wave around bones or lungs to get to structure of interest
What is acoustic shadowing useful in identifying?
bladder stones
What is acoustic enhancement and what is it used for?
Concept that sound waves travel through fluid more readily thus they have higher remaining energy when they pass through an area composed of fluid. Useful in differentiating a solid tumor from an abscess.
What is the most common display format in US?
Real Time - produces a moving picture - can see fetal movement and heart beating
In US, what type of display format isn't used much anymore.
A Mode
In US, what display format isn't used very often, produces a still life picture, and is also called "brightness mode"?
B Mode
In US, what display format is used w/ echocardiography, produces an "ice pick" view of the heart, and makes a line tracing of heart wall and valve action?
M Mode

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