Quiz 1 Flashcards
RAD/Gray=
Absorbed dose
REM/Sievert
Dose Equivalent
Roentgen=
Exposure
1REM=_______milliREM
1000mREM
You receive ___mREM/day
1mREM/day
1 X-ray= ______mREM
10mREM
A person who takes radiographs is expected to receive _______rREM/year
300mREM
What does the Bremsstrahlung x-ray refer to
Primary source of diagnostic x-ray
KVP=___________ (in terms of a camera_________)
Increasing KVP means (increased/decreased)
_______energy
_______# of rays
QuaLity (Contrast)
Increase energy
Increase # of rays
mAs=_________ (in terms of a camera________)
QuaNtity (shutter speed)
What is Photoelectric effect?
Primary absorbed dose -Z^3= tissue density Ex. Fat= Carbon-12 (C-12) 12^3=1728 ⬆️KVP=⬇️PEE
What is Compton Scatter?
Rays that are NOT absorbed
-independent of Z
No image is produced
Film is made out of______________crystals
⬆️ crystal size=______detail
Silver Halide
⬆️size= ⬇️ detail
What is the inverse square law?
It is a fraction of film distance (FD) and focal spot (FS)
If a film closer to the beam, the beam will have greater intensity
This gives you better detail without changing mAs
i1 = (d2)^2
___________ This number should be
What is the Heel effect?
The cathode side of the X-ray tube is stronger and so you will get better detail if you place the thicker part of the body on the cathode side
You have a film that has good contrast, but there is motion artifact. How do you fix this?
⬆️mAs (speed)
⬇️FD
What is a Pnumbra?
This is a shadow effect (like a comet and its tail)
The comet has good detail, the tail has poor detail
What is the difference between using a screen and not using a screen?
Screen No Screen
⬇️detail ⬆️detail
⬇️exposure ⬆️exposure
⬇️kVp/mAs ⬆️KVP/mAs
Grids have (increase/decrease) ___________scatter and use _______mAs.
The table-top method is used when the patient’s anatomy is________in size.
⬇️scatter
⬆️mAs 2-3x
Short KVP has (increase/decrease)_____kVp and ______mAs=______contrast and _____detail
⬇️KVP
⬆️mAs
⬆️contrast
⬆️detail
Long KVP has (increase/decrease)_____kVp and ______mAs=______contrast and _____detail
⬆️KVP
⬇️mAs
⬇️contrast
⬇️detail
How do you examine X-rays?
Roentgen imaging: change seen in tissues Location Margin Number Opacity Size Shape
What are the difference opacities?
Air: black Fat: black/grey Fluid/soft tissue: grey Mineral: white-grey Metal: white
ALARA stands for?
As Low As Reasonably Possible
What is the Mach phenomenon?
This is an optical illusion that mimics a false lesion
- false white or black lines may appear to be a lesion, these usually are seen over sharp edges of anatomy
- ex. Lines over bone may look like a fracture
What is Summation
When 2 objects superimpose each other and appear whiter due to increased density
-usually will have a grey area for each object as normal, than a whiter area where the summation in occurring
What is silhouetting?
When 2 objects of like opacity are next to each other the boarders are lost and they appear as one object
What orientation should X-rays always be placed?
- The animals LEFT should be placed to your RIGHT regardless of view
- animal’s head should always be placed with their head to the left on the table
Break down this view: D65Pr-PaDiO
D= Dorsal 65= angle from the ground to the beam Pr= proximal Pa= palmar Di= distal O= oblique
What does orthogonal mean?
90 degrees
What methods will you use to detect lesions?
FALSE NOMS F-function A-alignment L-location S-size E-enhancement
N-number
O-opacity
M-margins
S-shape
What kVp and mAs settings should you do to maximize contrast?
High KvP
Low mAs
In thoracic radiographs you should always shoot at peak (inspiration/expiration)
Inspiration
In abdominal radiographs you should always shoot at peak (inspiration/expiration)
Expiration
Describe horizontal beam
- The animal is laying lateral and you are shooting VD/DV
- this view is used for control gas for better contrast
Describe a compression shot
-using an object like a wooden spoon you can manipulate gas, fluid and tissue to enhance contrast, finding hidden anatomy or objects
Describe a urethral shot
This is a special view that involved pulling the hind limbs to the body and proximally, allowing the urethra to be seen behind it
How is a cat anatomy different then a dog?
Cats have:
- more peritoneal fat
- falciform mass (hepatic ligament)
- smaller spleen, should never be seen ventrally= splenomegaly
- pancreas tail can be seen in the left
- fat within gastrointestinal wall
- cecum= blind sac
What is tomography?
- An image that depicts a slice of anatomy
- free from super-imposition
What is a pixel
A representation of an average number of voxels of tissue
What is a voxel?
A value on a 3D grid
what alternative imaging system uses Hounsfield units?
CT
What is a HU?
- Linear attenuated effect
- x-ray converted to a grey scale
What is the gold standard method of diagnosis thoracic metastasis?
CT
CTs use “Windows”. A long scale window is _______wide. It has (high/low) contrast. And is used for examining_________. What areas are visible?
1000 pixels
Low contrast
For bone
All subtle grey areas
CTs use “Windows”. A short scale window is _______narrow. It has (high/low) _____contrast. And is used for examining_________. What areas are visible?
250 pixels
High contrast
For tissue
Enhances subtle differences in areas
Referring to CT:
Black areas are termed…
Hypodense or hypoattenuated
Referring to CT:
White is termed:
Hyperdense or hyperattenuated
What is needed for a hyperattenuated signal?
Iodine contrast media
Referring to MRI:
Black is termed:
Hypointensive
Referring to MRI:
White is termed:
Hyperintensive
MRI T1:
Fat=
Fluid=
Edema=
Fat=white
Fluid=black
Edema=black
What is T1 MRI used for?
Contrast studies using GADOLINIUM
MRI T2:
Fat=
Fluid=
Edema=
Grey
White
White
What is T2 MRI used for?
Diagnosing pathology
MRI STIR:
Fat=
Fluid=
Edema=
Black
White
White
What is STIR used for?
Diagnosing fat from fluid
MRI FLAIR:
Fat=
Fluid=
Edema=
White
Black
**White
What is FLAIR used for?
Diagnosing fluid from edema
What is tomography?
- An image that depicts a slice of anatomy
- free from super-imposition
What is a pixel
A representation of an average number of voxels of tissue
What is a voxel?
A value on a 3D grid
what alternative imaging system uses Hounsfield units?
CT
What is a HU?
- Linear attenuated effect
- x-ray converted to a grey scale
What is the gold standard method of diagnosis thoracic metastasis?
CT
CTs use “Windows”. A long scale window is _______wide. It has (high/low) contrast. And is used for examining_________. What areas are visible?
1000 pixels
Low contrast
For bone
All subtle grey areas
CTs use “Windows”. A short scale window is _______narrow. It has (high/low) _____contrast. And is used for examining_________. What areas are visible?
250 pixels
High contrast
For tissue
Enhances subtle differences in areas
Referring to CT:
Black areas are termed…
Hypodense or hypoattenuated
Referring to CT:
White is termed:
Hyperdense or hyperattenuated
What is needed for a hyperattenuated signal?
Iodine contrast media
Referring to MRI:
Black is termed:
Hypointensive
Referring to MRI:
White is termed:
Hyperintensive
MRI T1:
Fat=
Fluid=
Edema=
Fat=white
Fluid=black
Edema=black
What is T1 MRI used for?
Contrast studies using GADOLINIUM
MRI T2:
Fat=
Fluid=
Edema=
Grey
White
White
What is T2 MRI used for?
Diagnosing pathology
MRI STIR:
Fat=
Fluid=
Edema=
Black
White
White
What is STIR used for?
Diagnosing fat from fluid
MRI FLAIR:
Fat=
Fluid=
Edema=
White
Black
**White
What is FLAIR used for?
Diagnosing fluid from edema