The density difference between two adjacent areas on a radiograph
What is radiographic contrast?
100
List 3 advantages of using digital radiography over traditional radiography.
Faster, no chemicals, less retakes, can adjust, can measure and zoom, easily store images and send them, follow-up films are easier because everything is saved
info about organ structure and function, helps focus differential diagnosis, debilitated pateints
200
The degree of blackness or darkness on a radiograph
What is radiographic density
200
What is the globally accepted form to send digital radiographs via the internet and to court?
DICOM
200
Film speed is determined by what?
size of silver halide crystals - fast film has large crystals and require less radiation
200
List two things you should make sure happens to a patient before they have a GI study performed.
NPO 12-24 hours, enema 4-12 hours
200
The tissue reflects no echoes and appears black
What is anechoic
300
A device placed between the patient and the radiographic film that absorb non-image-forming x-rays (scatter)
What is a grid?
300
Explain how computed radiography works.
Cassette with photostimulable phosphor detector screen in that absorbs the x-ray energy. Place CR cassette into CR or IRD reader which opens the cassette and removes the CR plate. The CR plate is scanned by a helium-neon laser beam which stimulates the release of trapped x-ray energy as visible light. The light is transformed into an electrical signal, digitized and store in a computer. The CR plate is exposed to bright white light erasing it for its next use.
300
A thicker phosphor layer on an intensifying screen means x-ray absorption and light emission is __________________ and the image has ______________ detail.
increased, decreased
300
List two reasons why an animal may have a cystograph?
bladder stones, tumors, calculi, bladder rupture
300
Define hyperechoic.
Tissues reflect more sound back to the transducer than the surrounding tissues; reflects brighter white than surrounding tissues
400
Rank the following substances from lowest to highest according to their densities - water/fluid, metal, fat, gas, bone
gas, fat, water/fluid, bone, metal
400
Explain how CCDs (charged coupled device) work.
The CCD is attached to an intensifying screen which flouresces when exposed to radiation. The CCD captures this light and stores the energy in the form of "trapped" electrons inside the thousands of tiny elecronically isolated pixels etched into the CCD's surface. The elctrons are read out and converted from an analog signal to a digital signal.
400
Small phosphor crystals in an intensifying screen have ___________ light emission, require ____________ radiation, give ___________ detail, a ______________ image.
less, more, more, better
400
List 2 precautions when doing a cystography.
get urine sample first, proper urinary catheter technique, clean leaked urine off patient, proper distention of bladder, do not use barium sulfate, room air may cause embolism if there is an active bladder hemorrhage
400
Why is it difficult to perform ultrasounds on the GI tract?
Gas reflects sounds and prevents imaging of deeper structures and feces cause shadows
500
Rank the following substances from lowest to highest according to their x-ray penetrability - water/fluid, metal, fat, gas, bone
Metal, bone, water/fluid, fat, gas
500
Explain how a flat panel detector digital radiograph machine works.
There is a large x-ray intensifying screen coupled to an amorphous silicon panel or amorphous selenium panel serving as a light detector. Each detector is composed of a light sensitive area and a smaller area of electronics. The light is converted into a digital signal and the image is processed and read.
500
Intensifying screem speed is governed by 4 things. What are three of them?
Size of crystals, phosphorus layer thickness, reflective layer efficiency, dyes in phosphorus layer
500
List three downfalls with using a water-soluble iodine preparation when doing a GI study.
Fast transit time, hypertonicity, rapidly absorbs fluid in the alimentary tract losing contrast, becomes dilute, mucosal detail is poor
500
Explain how an ultrasound works starting with the probe and ending with the image.
"beam" is created by piezoelectric crsyatls that ossillate at several million Hertz per second within the transducer. The soundwaves interact with the tissues in the body and is reflected and an echo is received by the transducer. This is converted to an elctronic signal and processed through a computer.