DI Quiz 1 Flashcards
Which layer of the duodenum is the thickest layer?
Mucosal layer
(hypoechoic)
How do you double mAs?
Increase the time
Colon causes ____ on ultrasound
clean shadowing
MRI brain lesions show an increase in _____
water
1 clean (dark)
2 dirty (white)
Label A-D according to orientation
A- cranial
B- ventral
C- caudal
D- dorsal
Normal anatomy in the liver
Veins are Visible, not arteries or bile duct
Portal veins: hyperechoic wall
Hepatic veins isoechoic walls
Label A and B
A- Portal vein
B- Hepatic vein
Rank the 5 opacites in order from radiolucency to radiopacity
Radiolucent
Radiopacity
Air Fat Water Bone Metal
My cat loves sunny places
know order and direction
Anechogen(black)
hyperechogen(white)
My Cat Loves Sunny Places
Medulla Cortex Liver Spleen Prostate
Is a mass in the left lung lobe harder to see on a R or L lateral radiograph?
left lateral
What type of transducer is used on large animals?
2-5MHz
What type of transducer is used on tendons and small parts (like the eye)?
>10MHz
(linear)
What type of transducer is used on small dogs/cats?
7.5-10MHz
What type of transducer is used for medium sized dogs?
5-7.5MHz
What type of transducer is used for large breed dogs?
5MHz
Label A & B
A- underexposed (too light) kVp or mAs is too low
B- overexposed (too dark) kVp or mAs is too high
What can you do to better this image?
Increase mAs (problem bc increases time so shows movement)
Increase kVp**
What can be done to fix this image?
Decrease mAs
Decrease kVp
How much do we change mAs or kVp?
mAs is usually halved or doubled (decreases or increases the # of x rays by factor of 2)
kVp is not halved or doubled!! (change 16%-20%)
4
The 6 roentgen signs
Size, shape, number, location, margination, opacity
What causes the most interference on an ultrasound?
Air/fat
CT works by….
attenuating x rays emitted from the body
The shorter the wavelength, the ___ energy
more
When may ionizations occur?
if energy is too high in xrays
ionizations can be dangerous: cell death, mutation
Dose limits for pregnant women?
if you get pregnant you can still receive some dose
<5 mSv during gestation
must notify employer in writing of pregnancy
Reducing ones dose: ALARA
As Low As Reasonably Achievable
principle protection philosophy
Three things to reduce dose of radiation:
Time
Distance
Shielding
Inverse Square Law:
doubling the distance reduces the x ray intensity to ____
tripling the distance reduces the x ray intesnsity to ____
quadruple the distance reduces the x ray intesnsity to ____
double: 1/4th (1/2)2
triple: 1/9th (1/3)2
quadruple: 1/16th (1/4)2
1
Scatter radiation
degrades the image
increases personal dose of radiation
Shielding protects from what?
Types?
Gloves and gowns DO NOT protect from the primary beam- only protect from scatter radiation
Aprons: .5mm lead (Pb)
Thyroid shields: .25 or .5mm lead
Gloves: .5mm Pb
Glasses: .75mm Pb
How can we reduce scatter from the beam?
COLLIMATION
Badge Guidelines
Wear only your own badge
Do not wear badge during personal medical/dental procedures
Never intentionally expose badge
Never take your badge home
Wear at collar, outside of apron
Cathode:
Made from tungsten
x rays produced is proportional to amount of filament current (mA) and time (sec) current is “on”
Doubling mAs, ____ the number of x rays produced
doubles
mAs is the ____ of xrays produced
number
kVp is the _____ of xrays produced
energy
What does x ray exposure do to film?
EXPOSURE = BLACKNESS
An underexposed radiograph is too _____
light
(either kVp or mAs is too low)
An overexposed radiograph is too____
dark
(either kVp or mAs is too high)
If a radiograph is too light, not enough x rays reached the film. How to correct this?
Increase mAs: if increase time, motion will be a problem
Increase kVp
Radiograph that is too dark, because too many x rays reached the film.
How can we correct this?
Decrease mAs
Decrease kVp
High contrast image
low kVp, high mAs
few shades of grey
better for fatty areas
Low contrast image
high kVp, low mAs
many grey shades
better to see the lungs
What kVp should I use on film for thorax?
use high kVp, low mAs
already have subject contrast due to air in lungs
air provides contrast
What kVp should I use on film for abdomen?
fat provides contrast
subject contrast needs to be maximized by technique
use low kVp, high mAs
How to correct this radiograph?
Decrease the mAs
Decrease the kVp
To increase contrast we ____ kVp
decreased
This radiograph was made using 5 mAs and 100 kVp. The best technique to try next is….
decrease mAs to 5, increase kVp to 120
Grids help to ____ scatter, but we need ____ x rays when using grid
reduce scatter
need 2-3x more xrays
located between xray source and plate/cassette
Reasons for a radiograph to look to dark?
kVp or mAs too high
xray tube too close to film
technique set for grid but grid not used
light leak in darkroom
what causes a radiograph to be too white/light?
underdeveloped
What format are digital rads in?
DICOM
Digital imaging communications in medicine
LARGE files
What is included in a DICOM file?
image
header: practice, patient, device
Type of digital that requires a cassette?
doesnt?
CR: computed radiography
DR: direct digital radiography
How do film and DR differ?
CONTRAST!
contrast is better in DR
Advantages of digital?
EXPOSURE LATITUDE
CONTRAST OPTIMIZATION
Exposure latitude is the extent to which a film can be
over or underexposed and still achieve an acceptable result
image looks like bone loss but can actually be…
Image Dropout!!!
massive overexposure- causes anatomy to disappear
Contrast optimization is
a smoothing of the grey scale
entire image will have better contrast/differences
Contrast resolution is highest on what imaging machine?
MRI
(MRI, CT, DR, Film) highest to lowest
Tomography
images are slices from patient
since rads are 2D, tomography solves this
Contrast medium
iodinated
given IV
attenuates x rays
enhances visibility of vessels, leaks, GI tract
MRI _____ is much greater than CT
contrast resolution
MRI image appearance is dependent upon
chemical composition
water
fat
(most lesions have increased water)
FLAIR
fluid attenuated
protons in tissue water
STIR
null signal from fat
Reasons for MRI in Vet med
Neuroimaging (brain/spinal cord)
Musculoskeleton (equine/canine)
tumor staging
What kind of image is this?
CT
What type of MR image is this?
T2 weighted (fat and water has signal)
T1
protons in fat
T2
Protons in free water, tissue water, fat
All 5 opacities can be seen… label them!
Magnification
magnified image will be larger and less sharp
Superimposition
A real structure is projected in an unexpected location and is misinterpreted as a lesion
Summation
two structures overlap and create a summation opacity that is not actually present in patient
Silhouette sign
the effacement (loss of visualization) of the border of 2 structures of the same radiographic opacity that are in contact
(image is showing the pulmonary veins!!!! since lungs and heart are the same opacity, they superimposed to make pulmonary vein look like its part of the heart)
Orienting images
lateral: patients head facing to viewers left
VD/DV: patient left on viewers right
proximal to top
Abdominal rads: ___ is needed for contrast
FAT
Boundaries of abdominal rad
cranial: edge of diaphragm
caudal: greater trochanter of femurs
Propagation velocity value
1540m/sec
The higher the frequency, the ____ resolution & ____ penetration
better resolution
low penetration
superficial structures
Low frequency, ___ resolution and ___ penetration
low resolution
better penetration
Attenuation
the loss of ultrasound
increased with distance from transducer, higher frequency (shorter wavelength)
Enemies of US?
air and bone do not get penetrated
strong interface
What artifact on US?
Clean Acoustic Shadowing
What artifact on US?
Dirty acoustic shadowing
Acoutstic enhancement
tissue distal to fluid looks brighter (hyperechoic)
Name the US artifact
edge shadowing
small shadow at edge of round structures
Name US artifact
Slice thickness artifact
-at curved surfaces like bladder (can mimic sediment)
Name US artifact
Mirror Image Artifact
highly reflective air/fluid interfaces like diaphragm-lung
concave surfaces
false image that is produced on the other side of the reflector due to its mirror like effect
High gain is a ____ image
lighter
Location of animal and machine during US
machine on left side of table
right side of animal since they are VD
head of animal facing machine
Anechoic
BLACK
very low intensity of returning echos
Hypoechoic
Less echoic than other structures
(darker)
Isoechoic
same echogenicity as another structure
Hyperechoic
higher echnogenicity than other structures
(lighter)
Normoechoic
as expected for organ
Doppler vascularity
red towards us
blue away
Triad
use split screen to compare organs in different planes
Free fluid in abdomen
earliest accumulation in apex of bladder b/t lobes of liver
1
Hypoechoic liver DDX
(Dark)
acute hepatitis
venous congestion
lymphosarcoma
Hyperechoic liver DDX
(lighter)
diabetes mellitus
hyperadrenocorticism
hepatic lipidosis
lymphosarcoma
Sludge seen in gall bladder!
normal in animals
Thickened gallbladder wall
cholecystitis
Mineral: hyperechoic casting a clean shadow in gallbladder
choleliths
what is this structure?
normal cat gallbladder
spleen > liver > kidney
Inspiration vs expiration
What species? What is arrow pointing to?
dog
spleen
What view is this?
Left lateral
pylorus filled with air
What view is this?
Right lateral
