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VDI #1 Exam #2

Diagnostic Imagining Exam #2 Weeks 4-7

QuestionAnswer
X-Rays are capable of penetrating what types of materials? Tissues thru which the rays can pass
True or False: X-Rays are visible. False
The source of the x-rays used in radiology is: the x-ray tube
List the steps that occur in the x-ray tube to produce an x-ray. 1. Filaments heat up->2.Release electrons->3.accelerate toward the anode->4. exit tube verticle as an x-ray beam
What does the "kilovoltage" control? Kilovoltage peak or kVp
What does the "milliamperage" control? Milliamperage Per Second
Why is tungsten used as a target material? Its very heat tolerant
Describe the difference between the stationary anode and the rotating anode. SA=>fixed RA=>rotates on a spindle to allow for distribution of heat
What is the "heel effect" and how does it affect radiographs? When all the energy paced in rapidly moving electrons comes to an abrubt stop when encountering the target in the x-ray tube.
What is scatter radiation? Produced by x-ray beam bouncing off the patient.
Why is scatter radiation a concern? It bounces back up off of the patient, frequently into the area where the x-ray tech is restraining animal.
How can scatter radiation be reduced? Standing uprigh position and turn face away while beam is on.
What are 3 variables to be set to create/provide a diagnostic radiograph? milliamperage, exposure time and kilovoltage
The milliamperage setting will control the number of x-rays produced. What would the result be if you increase the mA? What about if you decrease the mA? Radiographic density-film blackness is increased. A reduction in radiographic density= lighter film
How does the exposure time effect the amount of electrons produced? Is how long the anode is positively charged. The longer the exposure time, the more electrons flow to the anode.
Why should you always use the highest mA setting and the lowest time setting available when calculating mA's? to take a quick and clear x-ray
Calculate mA's for the following: a. 20mAx 1/2 sec=______ mAs b. 100 mA x 1/10 sec = ______ mAs c. 1000 mA x 1/10 sec= _______mAs d. 300 mAx 1/160 sec = ______mAs A. 10 mAs B. 10 mAs C. 100 mAs D. 48 mAs
How does the kilovotage affect eh quality of a radiograph? regulates voltage differential applied between the anode and the cathode in the tube. Higher voltage=faster electrons are accelerated and greater energy of x-ray beam.
What type of mAs and kVp setting is used for soft tissue radiographic examinations?
What types of settings would you use for bone structure? the distance between the target in the x-ray tube and the surface of the x-ray detector
What is the standard if you increase the FFD? # of x-rays reaching the film decreases
What is the standard if you decrease the FFD? # of x-rays reaching the film increases
How would you increase radiographic density? turn up mAp or increase kV
Radiographic detail degree of sharpness that defines edge of an aatomic structure
Radiographic Contrast Desnisty or opacity
Radiographic density degree of blackness of the film
List factors that may affect radiographic Detail FFD, Movement, OFD, Size of focal spot
Which exposure factor has the greatest influence on radiographic contrast? Kilovoltage
Which exposure factor has the greatest impact on radiographic density? mAs setting
How is the technique of magnification used to produce a diagnostic radiograph? object is placed halfway between the film and focal spot of x-ray tube to produce a radiograph twice as large as life size
X-Ray Cassette A lightproof encasement designed tohold x-ray film and intesifying screens in close contact.
Intensifying screen Sheets of luminsecent phosphor crystals bound together and mounted on a cardboard or plastic base.
Screen Speed Refers to its ability to convert absorbed x-ray energy into visible light
Nonscreen film film that is more sensititve to ionizing radiation than to fluorescent light
Reflective layer A layer of an intesifying screen that reflects the light from the phosphor layer toward the film
Screen film Film with silver crystals that is more sensitive to fluorescent light emitted from intesifying screens than to ionizing radiation
What are the 2 types of cassettes that are used in Vet medicine? Nonscreen cassette or direct-exposure in a cardboard cassette Image intesifying screen in a rigid cassette
Which of the 2 cassette types is most common? image intesifying screen in a rigid cassette
What are the benefits of using intesifying screens? 1. It prolongs the life of the tube 2. decreases the amount of exposre to patients and technicians 3. Reduces the risk of patient motion
how often should intesifying screens be cleaned? At least once a month
What is the normal life span of a rare earth screen? 10-12 years
True or False: Nonscreen film requires greater exposure. True
T or F: Screen film is more sensitive to ionizing radiation. F
T or F: Nonscreen film produces poorer detail. F
T or F: Nonscreen film is highly sensitive to fluorescent light emitted from intesiifying screens. F
Describe the components of x-ray film Light sensitive emulsion containing silver halide crystals.
Can you use any combination of intesifying screens and x-ray film? Why or why not? No- size
What is film latitude? The exposure range of a film that iwll produce acceptable densities.
How should unexposed film be stored and handled? Stored verticle so no pressure spots Store in low humidity and cool area Store away from radiation, vapors, formalin, peroxide, or ammonia Handle on edges only
A processed film that has not been exposed to ionizing radiation or visible light will apear? Black
Which of the film-screen systems is most commonly used in vet medicine? Medium Speed or par speed.
What is a Technique chart and how is it used in radiography? provides suggested exposure factors to use based on the anatomic part being radiographed, the thickness of the tissue, and the position of the patient
What is Santes' rule? How does it apply to producing a radiograph? alternative method of developing a variable kV technique chart. useful only if mA and time factors are limited on the radiography unit and only on a single phase unit
What is the formula for Santes' rule? (body measurement in cm) x2=_______+(sid+grid factor)
How is a technique chart created? Trial and error
What factors will influence the technique chart? types of cassette and intesifying screen, type of x-ray film and FFD must be consistant
What type of patient should be used for creating a technique chart? Cooperative or sedated adult dog moderate size (50 lbs) and muscle clean and coat should be either medium or short
Any body part exceeding this measurement requires the use of a grid to reduce fog-producing scatter radiation? 10cm
If an initial radiograph is too light, how should the kVp and mAs be adjusted? increase kVp by 10-15% or increase mAs by 30-50%
If the initial radiograph is too dark, how should the kVp and mAs be adjusted? decrease kVp by 10-15% of decrease mAs by 30-50%
What is the formula to calculate mAs? time x MA=mAs
What is a Technique chart and how is it used in radiography? provides suggested exposure factors to use based on the anatomic part being radiographed, the thickness of the tissue, and the position of the patient
What is Santes' rule? How does it apply to producing a radiograph? alternative method of developing a variable kV technique chart. useful only if mA and time factors are limited on the radiography unit and only on a single phase unit
What is the formula for Santes' rule? (body measurement in cm) x2=_______+(sid+grid factor)
How is a technique chart created? Trial and error
What factors will influence the technique chart? types of cassette and intesifying screen, type of x-ray film and FFD must be consistant
What type of patient should be used for creating a technique chart? Cooperative or sedated adult dog moderate size (50 lbs) and muscle clean and coat should be either medium or short
Any body part exceeding this measurement requires the use of a grid to reduce fog-producing scatter radiation? 10cm
If an initial radiograph is too light, how should the kVp and mAs be adjusted? increase kVp by 10-15% or increase mAs by 30-50%
If the initial radiograph is too dark, how should the kVp and mAs be adjusted? decrease kVp by 10-15% of decrease mAs by 30-50%
What is the formula to calculate mAs? time x MA=mAs
What is screen craze? Very old screens may result in a white speckled pattern artifact.
T or F: Dropping a film cassette on a hard surgace may result in loss of contact between the intesifying screens and film, which will result in a blurred image. True
Intesifying screens Made of layers of tiny crystals bonded together on a plastic support and convered with a protective coating
If a commercially produced screen cleaner is not available to clean intesnsigying screens, what can you use? 70% alcohol or distilled water
The reflective layer of an intesifying screen: reflects light from the phosphor layer of the screen towards the film
A rare earth screen is advantageous for vet radiography as they: reduce mothion artifacts, require fewer x-rays to produce an image, and reduce patient radiation dose
The main disadvantage of rare earth screens is? cost
For trial exposure, a normal dog witha lateral measurement of ____ should be selected. 11-16 cm
Created by: gina.baker