Diagnostic imaging Flashcards
What are the “joints” in the skull referred to?
Sutures. Sutures are fibrous bands of tissue that connect the bones of the skull. (In neonates, the sutures are open and allow for growth of the brain and skull)
Linear artifacts on a film are usually cause by what?
Grid.
The settings that affect exposure without changing contrast are ____
milliamperage (or mA) and exposure time. Increasing either will increase the exposure of the film.
Changing kilovoltage (kvp) changes the amount of ____
Contrast
What is a myelogram?
A diagnostic imaging test that uses contrast dye into the subarachnoid space and either xrays or CT to look for problems in the spinal canal, nerve roots, and other tissues.
mAs is a measure of the ____ ____.
Total exposure. It is the product of mA and time in seconds. (Generally, it is best to maximize the mA and minimize exposure time to decrease motion artifacts)
MRI compatible devices are made with non-ferromagnetic metals such as ____.
aluminum, titanium, brass, and “others”
Magnetic (or ferrous) metals consist of ___.
Iron, nickel, and cobalt. (INC.)
Invertebral disc spaces appear ____ towards the center of the film and ____ towards the end of the film.
Wider, Narrower
For ultrasound probes, higher frequency probes have ____(increased/decreased) image resolution and _____ (increased/decreased) penetrating ability relative to lower frequency probes.
Increased, decreased
Which 3 structures of the body are the most sensitive to radiation?
The lens of the eye, (and those with rapidly dividing cells) bone marrow, gonads (ew)
What is a Potter-Bucky diaphragm
A moving grid placed between the patient and the xray film that can be repositioned to reduce visual artifacts caused by secondary radiation
What is a grid
A series of short strips of lead that is placed over the cassette, absorbing all radiation that does not go between the strips
What would cause a developed xray to appear yellow?
Yellow radiographs are usually seen when the fixer solution is low, or fixation time is too short
What is the bisecing angle technique?
a technique used to prevent distortion when it is not possible to place the film parallel to the structure of interest and perpendicular to the xray beam (common in dentistry)
What is skyline view?
A technique used to decrease superimposition of structures, usually in an equine carpus
What is a DLMPO xray?
dorsolateral-palmaro/plantaromedial oblique
What is the metallic element on xray that turns black when exposed and run through the radiograph development process?
Silver. Film go into the developer first which reduces exposed silver halide into elemental metallic silver which is black.
Which trimester of pregnancy is the most important to follow radiation safety?
The first trimester (the first 3 months)
What is a pyelogram?
An intravenous pyelogram (IVP) is an xray examination of the kidneys, ureters, and urinary bladder using iodinated contrast material IV and excreted through the kidneys (particularly the upper urinary tract)
The fetal skeleton ossifies at ___-___days for a dog, and __-___ in the cat.
42-45 days for a dog, 35-39 days for a cat. The scapula/humerus/and femur develop first, then the ribs, then the teeth and toes
adjusting kilovoltage or kvp changes what?
kilovoltage affects Kontrast (higer kvp = LESS contrast)
Heartworm disease on xray causes ___ and looks like ___.
Right heart enlargement, and enlargement of pulmonary arteries. It looks like a “reverse D” on a VD.
What does the heel effect refer to?
The xray beam intensity declines toward the anode (or positive) side of the xray machine
For an xray vet tech, what is the maximum permissible dose of radiation they can receive in 1 year?
50 mSv.
What anatomical location can the atlas and axis be found?
The cervical (neck) vertebrae C1-2 are known as the atlas and axis and articulate with each other
After a myelogram, what should you do for dogs to decrease the risk of procedure-related complications?
Elevate the head. Dogs have a risk of having seizures due to the contrast administration.
On ultrasound, what color is fluid?
Black (hypoechoic or anechoic)
What happens to make an xray taken and processed turn out completely clear?
The exposed film was put in fixer before developer. If placed in fixer first, all of the silver halide crystals will be removed, leaving a clear image.
When placing lateral xrays of the knee on a viewer, how should it be oriented?
The cranial or dorsal side of the limb should be to the left and the proximal aspect should be toward the top of the viewbox.
If the focal-film distance (or the distance of the film relative to the xray source) is too short, what will be the result?
Increased film density
Which type of urinary stone is lucent and does not typically show up on an xray?
Urate and cystine crystals. These crystals require ultrasound or contrast studies to diagnose.
What is the purpose of a grid on an xray table?
To prevent scatter radiation from reaching the film.
When you push down the pedal half way prior to taking an xray, what is happening?
The anode rotates and the filament is heated.
Where are electrons generated in an xray machine?
At the filament of the cathode. (The kVp applied directs those electrons to the anode, where they hit a tungsten target to produce xrays)
What is the main difference between non-screen film and screen film?
Non-screen film has the image produced by xrays themselves, whereas screen film uses light produced in an intensifying screen to generate the image.
Screen film is more sensitive to light and non screen film is more sensitive to xrays.
What 3 things help to minimize your exposure to radiation while taking xrays according to the US NRS?
Time, Distance, Shielding. TDS.
Which animal does not have a gall bladder?
A horse
What is ALARA?
“As low as reasonably achievable”
The radiation safety principle that all personnel should take all reasonable efforts to minimize their radiation exposure.
What does MPD stand for?
maximum permissible dose, monitored by a dosimeter badge
What does rad stand for?
“radiation absorbed dose”, an old measure of absorbed dose that has been replaced by the Gray (Gy), which equals 100 rad.
What does rem stand for?
“radiation equivalent is man”, a measure of absorbed dose x a quality factor that takes into account the type of radiation that was absorbed. Sievert (sv) which is 100 rem
What does a double-contrast cystogram involve?
Soluble positive-contrast media and air injected directly into the bladder.
Which bone articulates with the patella?
The femur, at the level of the trochlear groove
What is the mediastinum?
The central compartment of the chest, located between the right and left pleura. Contains all the thoracic organs except the lungs.
Why is tungsten ideal material for the filament and trget of an xray machine?
It has a very high melting point
What does a PACS system consist of?
A server, a workstation, and a viewing monitor. The monitor is the most critical to image quality.
How do you increase density of the film?
You have to increase the number of xray photons reaching the film, and decreasing the distance from source to film.
The olecranon is a structure of what bone?
The ulna. This is found at the proximal portion of the ulna and forms the point of the elbow. The triceps attaches there.
What are the parts of an xray cassette in order from front (where xray enters) to back?
Cassette front, padding, intensifying screen, film, intensifying screen, padding, cassette back.
What should you adjust to (always) improve radiographic image quality?
Use the highest milliampere (mA) setting and lowest time(s) setting possible to achieve desired mAs.
(mA x time(s) = mAs, which determines the degree of film exposure for a given kVp)
mAs is a measure of ____.
Total exposure
mAs is the product of mA and time in seconds. so if kVp is 50, and mAs is 12.5…
250 mA, 1/20 seconds would be appropriate
What is the explanation for a film appearing darker (more exposed) towards one side of the film?
The xray beam is usually more intense on one side of the field. This is knows as the Heel effect.
In order from least to most radiodense (darkest to whitest) on xray, how would you order gas, soft tissue and fluid, fat, metal, and bone?
Gas, fat, soft tissue and fluid, bone, metal
A dorsoproximal-dorsodistal oblique xray of the carpus is frequently referred to as what type of xray?
Skyline view
What is the benefit of using a larger filament?
Higher exposures can be used.
What is intended to shield the user from the primary xray beam?
Collimator. Only the collimator contains enough lead to shield the primary radiation beam.
What does the inverse square law state?
The intensity of the xray beam is inversely proportional to the square of the distance from the xray source. Therefore the intensity is greater as the cassette is moved closer to the source.
In radiation safety, what is the difference between the “rad” and the “rem”?
Rem applies a quality factor to rad.
Which settings influence xray beam quality?
kVp and filtration. “quality” refers to the energy distribution of the photons that are emitted.
Where are electrond generated in an xray machine?
At the filament of the cathode.
