VTP Diagnostic Imaging Flashcards
How soon can pregnancy be identified by ultrasound in a horse?
11 days
When placing craniocaudal radiographs of the stifle joint how should film be oriented?
- Lateral side of right limb to the left
- Lateral side of left limb to the right
What is the earliest time a fetus can be seen on radiograph?
43 days
Which disorder does an intravenous pyelogram detect?
Ureteral stones
What condition is contraindicated for Upper GI radiographs using barium?
Aspiration pneumonia
What conditions are contraindicated for using iodide contrast agents?
dehydration and renal insufficiency because it causes osmotic diuresis
What causes yellow radiographs?
Problem with fixer solution
How is mAs calculated?
mA and time in seconds
Why is tungsten ideal material for an xray machine?
- High melting point
- High number of electrons
- Does not conduct heat
- High atomic number
What is the difference between screen film and non-screen film?
Non-screen film is more sensitive to xrays
How to increase radiographic density
- Increase energy of xrays
- Increase number of photons
- Decrease distance from source to film
What is the inverse square law?
Exposure at twice the distance will be reduce to 1/4. Therefore if object is twice as far away then MaS needs to be increased by 4
How do you avoid distortion with xrays?
xray beam should be perpendicular to the bones
What happens if bones are not perpendicular to the xray beam?
They are foreshortened
What happens if bones are not perpendicular to the cassette?
They are elongated
What are the properties of xrays compared to visible light?
Xrays have a higher frequency and shorter wavelengths
What type of urinary stones are translucent and dont show up on radiographs?
urate and cystine
What is rad
The basic unit of absorbed dose
What is rem
Applies a quality factor to rad
What is gray?
units of absorbed dose
What is sievert?
Units of effective absorbed dose
What is the metallic element on radiographs that turns black when exposed?
silver
What do you do if the radiograph appears much too light throughout the area of the patient?
Increase Kvp
When should abdominal radiographs be taken?
Full expiration
What appears hyperechoic or bright white on an ultrasound?
Bone and Gas
What would be enlarged on a chest radiograph of a dog with heartworm?
Pulmonary arteries
What components affect xray beam quality?
kVp and filtration
What material is MRI made of?
Aluminum
When is a tabletop technique used for radiographs?
When an image is not too thick typically less than 10 cm such as an elbow
When an abdominal radiograph shows a boxing glove shape of air what is it?
GDV
If an xray machine has the ability to use 2 different sized filaments at the cathode what is the advantage of using a larger filament?
Higher exposures can be used
What is the order and function of the fixer and developer?
- Developer converts
- Fixer dissolves
What is the purpose of the potty bucker diaphragm?
Eliminate grid lines on the film
What are the three things you can do to minimize radiographic exposure?
time distance and shielding
What technical error increases film density?
Focal-film distance is too short
What technical errors decrease film density?
- mas too low
- Intensifying screen speed too slow
- Temperature too low
- KV settings to low
What is the function of an xray cassette?
To decrease the exposure necessary to create an image on a film
Why is filtration used at the portal of the xray tube?
eliminate low energy radiation that does not contribute to the image
Why should you collimate the beam?
Decrease radiation dose to patient and technician
Why is a bisecting angle technique used in dental radiography?
It is frequently impossible to for the tooth and film to be parallel to each other so the bisecting angle prevents foreshortening and elongation
What is a double contrast myelogram?
Soluble positive contrast media and air is injected directly into the bladder
What is the correct order of least to most radiodense material? (darkest to whitest)
Gas
Fat
Soft Tissue and Fluid
Bone
Metal
What is the purpose of a grid on an xray table?
To prevent scatter radiation from reaching the film
What tissue is most sensitive to radiation?
Bone marrow
What is the heel effect?
Xray beam intensity declines toward the anode side of the xray machine
What position is best for diagnosing GDV?
Right lateral abdominal radiograph
What procedure requires the use of contrast dye?
Myelogram
What is a DMLPO?
Dorsal Medial Lateral Palmar Oblique
What is DMLPO aka?
Medial Oblique
What is the technique for a DMLPO?
The beam comes from a 45 degree between dorsal and medial sides of the limb
AND
film is placed 45 degrees between the lateral aspect and the palmar aspect
Why are oblique radiographs used?
To decrease the superimposition of structures
Where does most of the radiation come from to a technician?
Scatter from the patient area
What is a pneumocystogram?
A radiograph of the bladder after having had air injected into it
What happens in the xray machine when the pedal is half pressed?
The anode rotates and the filament is heated
What happens in the xray machine when the pedal is fully pressed?
The charge in the xray tube accelerates the electrons which hit the target at the anode emitting xrays
What shields the technician from the primary xray beam?
collimator
How do you position a dog fro a suspected left sided cruciate ligament injury?
Patient in left lateral recumbency with the leg against the cassette
What is a cystogram?
Radiographic study of the urinary bladder
Why is a horizontal beam used?
Identify air or fluid in a body cavity
Why is a skyline view used?
decrease superimposition of structures
What is true regarding radiography of the vertebrae?
IVD space is wider toward the center of the film and narrower toward the end of the film
Where should the field be centered in a lateral thoracic radiograph?
5th rib and caudal border of the scapula
What is a skyline view?
Dorsoproximal-dorsodistal oblique radiograph
What is the common factor that prevents a diagnostic radiograph
motion
What is the order of components in an xray cassettE?
Cassette front
Padding
Intensifying Screen
Film
Intensifying Screen
Padding
Cassette Back
What is a fistulogram?
A radiograph after a contrast agent is administered into a draining tract
When should a thoracic radiograph be taken?
Full inspiration
In a DLPMO radiograph where will the xray unit be and where will the cassette be?
Xray beam should be from the dorsal side of the limb
and
Film will be on the medial side of the limb
What is the difference between high frequency probes and low frequency probes?
Higher frequency have increased image resolution but decreased penetrating ability
What position should a patient in respiratory distress not be placed in?
Dorsal
What causes linear artifacts on a film?
Normal gridlines or the beam not being centered
What do processing machine errors cause?
Streaks
What happens to film if it does not go through the developer?
It will be clear
Where are electrons generated in the xray machine?
At the filament of the cathode
What settings on the xray machine can affect exposure without affecting contrast?
tIME AND mAS
What is the maximum permissible dose of radiation to a technician in 1 year?
50 mSv
What should you do after performing a myelogram?
Elevate the head to reduce the risk of seizure
What would cause a film to be yellow-brown?
Incomplete washing of the film
What principle will always improve radiographic image quality?
Highest mA setting and lowest time setting
