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Exposure I Final

Radiology Exposure I Final

QuestionAnswer
If a lower mA is activated on the generator panel, AEC will use a longer time of exposure
AEC devices provide a diagnostic quality radiograph when the part is positioned directly over the chamber
When an AEC detector sets over an area of increased fluid, exposure to the IR will be higher
US Public law requires automatic termination of AEC exposure at _____mAs above 50kVp. 600
With an ionization chamber device, the electrical charge produced is in proportion to the amount of radiation received. True or False? True
What will result in more exposure to the image receptor, but not alter the dynamic range when using AEC? changing the density control to +2
AEC devices operate by measuring radiation transmitted through the patient
The purpose of the back-up timer is to Set the maximum exposure time possible
The dectectors, cells or sensors can differentiate between secondary and scatter radiation False
Your next KUB patient has Hyperstenic body habitus. Acknowledging that fact, you increase the density control to +2. How will the length of exposure change, as compared to density control at N? Exposure time will remain the same
You are using AEC with the center sensor activated. If the centering point for an AP lumbar spine is set incorrectly over the liver, the radiograph will be lighter in film density or show underexposure
Which one of these would assist in the control of motion in the AEC mode? Increase the mA
Nsme four considerations with any AEC exposure Patient position kVp level Focal spot size Sensor selector
Which statement is false concerning scattering radiation? Scattering radiation does not contribute to image density
When kVp increases from 70 to 80 more photons undergo interaction with matter
As the beam size of radiation changes from 10x12 to 14x17 inches, scatter production will increase
Identigy the beam restriction device composed of a flat sheet of lead with a circular opening Aperture diaphragm
A collimator device has how many sets of lead shutters? 2
You have produced a scout AP KUB (14x17 IR) using AEC mode. After fluorscopy, the radiologist requests an image of only the RUQ which requires only a 10x12 IR. The second image will produce a higher mAs readout
Components of a collimator device are light source, mirror and shutters
What collimator components must be an equal distance from the mirror? Light source and focal spot
The collimator mirror is mounted at an angle of 45 degrees
A visible sign of collimation to the necessary anatomical region is evidenced by the _____ around the radiographic image unexposed area
A radiograph produced with AEC exhibits increased exposure/film density due to excess scattering radiation. A second image is produced, but with increased collimation. The second image will show what level of contrast? No change in contrast scale occurs
If an uneven beam field is projected onto the patient's anatomy, it is due to lead shutter(s) being misaligned
What happens to exposure time when kVp is decreased to reduce scattering radiation when in the AEC mode? Exposure time increases
The source of off-focus radiation is any point other than the focal spot
What would NOT be classified as a beam restriction device? Port
What feature do secondary radiation and scattering radiation have in common? Decrease in intensity of the beam
The principal factors that affect the amount of scatter produced are mAs and the type of irradiated material False
A lead blocker or leaded rubber may serve as a beam restrictor True
If the primary beam is collimated from an activated AEC sensor, the result would be a change in exposure quantity to the IR
Automatic collimators are known as positive beam limitation devices. True
Back up time of most AECs is set longer than the anticipated manual exposure time
When mAs is reduced, the Photoelectric to Compton ratio will remain the same
As more photons pass through the irradiated material unaffected, the resulting image receptor exposure has greater level of exposure to the IR
Volume of the irradiated tissue increases as radiation field size increases patient thickness increases
The shutters of a collimator will Reduce field size Reduce penumbra Reduce off-focus radiation
As collimation increases,patient dose _____ and image contrast ______ decreases, increases
Exposure factors used for an AP KUB with a 14x17 cassette will not be sufficient for a bladder image on an 8x10 cassette. Exposure factors must be changed to compensate for the reduction in field size by increasing mAs 20-50%
Increased collimation refers to a smaller radiation field True
Scattered photons will strike an area of he cassette unrelated to the anatomical area from which they were produced/created True
The most common phosphor used for CR imaging plates is barium flurohalide bromides
The latent image in CR imaging is created by energy transfer involving Photoelectric interaction
When the CR imaging plate is scanned by the laser the phosphors release energy in the form of light
A photostimulable imaging plate includes A phosphor layer, a conductor layer and a protective layer
During CR imaging plate processing, the laser frees trapped electrons,allowing them to return to a lower energy state. This process is known as Photostimulated luminescence
During image acquisition, laser light scans the IP in a raster pattern which means line by line
As increased collimation is used with a digital image, the image contrast will increase
Which phosphor shape produces more light diffusion, thereby reducing spatial resolution of the digital image? Turbid or powder phosphor
Translation refers to the laser scan across the imaging plate multiple times
Erasure light bulbs diminish in the level of output over time True
What is NOT a determining factor of spatial resolution? Conductive layer thickness
Spatial resolution is associated with contrast of the image. Another name for contrast resolution is dynamic range
Which form of digital data is classified as "noise" Scattering energy
Speed class of an imaging plate is determined by the amount of photostimulable luminescence or PSL during the laser scan True
Upon laser beam scanning of the imaging plate, the emitted light is detected by the _______device that amplifies the light. photomultiplier
It takes longer for the AEC to shut of the exposure on a thicker body part because the quantity of radiation is reduced
During an AEC exposure, the sensors activated should be covered by the ______ anatomy thickest
It is acceptable to override an automatic collimator (PBL) in order to collimate tighter to reduce patient dose
You have produced an incorrect level of exposure to the IR while in AEC mode. Name two reasons why this could result Used all of the energy available Panel not set correctly
Define averaging in relation to AEC exposure technique averaging has to do with the 3 sensors and the energy produced from each one that is converted into a digital image
Using kVp as the correction factor, increase image density/level of exposure by 100%. Use original factors of 10mAs @75kVp 5 mAs @ 85kVp
Maintain image density/level of exposure. INcrease kVp by 15% and state the new factors. Use the original factors of 40 mAs @ 80kVp 20mAs at 90 kVp
Maintain image density/level of exposure. Double the mAs value and state the new factors. Use the original factors of 30mAs at 70kVp 60mAs @ 60kVp
xray quality is numerically represented by GSD
Which one of these would display the most subject contrast? A muscular patient
How many half-value layers must be added to the primary beam to reduce the intensity to less than 20 percent of its original value? 3
Aluminum has an atomic number of 13
What results when longer wavelength photons interact with anatomy Short or high scale contrast
As kVp is increased, the primary beam is composed of higher frequency and shorter wavelengths
What will approximately double the exposure to the IR/film density? Increasing kVp by 15%
An adjustment from 70 to 80 kVp wil produce Wider exposure latitude, less patient absorption, shorter wavelengths
If the original radiograph shows good quality and kVp is increased by 15% Density/exposure to the IR increases, contrast decreases
Which interaction involves the production of secondary radiation? Photoelectric
If the original radiograph shows good quality and the mAs is increased by a factor of 2 density/exposure to IR remains the same, contrast increases
Increasing the kVp on the control panel will cause an ______across the xray tube increase in the speed of the electrons
How does high kVp, such as used with upright chest exams, affect radiographic contrast? Produces longer or low scale contrast
As kVp increases, ______ mAs will be needed to produce an image of equal exposure less
In lower kVp range, a 15% change has a greater impact on xray emission than at higher kVp values. Consider the example 50kVp vs 100kVp. True
What is NOT TRUE about optimal kVp? It determines total quantity of primary radiation
Higher kVp correlates with wider exposure latitude? True
Which patient would produce the most scattered radiation? 26cm abdomen
Increased scatter radiation in the exit or remnant beam will cause an increase in IR exposure
What happens to patient absorption of energy, as kVp increases? It decreases
The initial rad image exhibits underexposure. If kVp is increased as the correction it will affect more than one but not all
Long scale contrast is defined as black to many gray shades to white
Secondary radiation continues in a diverging direction, scatter is changed in direction of travel. True
Secondary radiation is lowered in intensity from the primary beam, as is scatter True
What is NOT TRUE concerning the relationship between image density and contrast? mAs is a quality factor and affects image density
Which set of factors produces a rad with the highest scale of contrast? 30mAs @50kvP
The 15% rule states that Density may be halved by decreasing kVp by 15% Density may be doubled by increasing kVp by 15%
Name 3 true statements about scattered radiation It has less energy than primary It contributes to density on the image It travels in a different direction than primary
Increasing energy of an incident electron results in the production of an xray photon with greater energy
As kVp _____ a ______ range of photon energies is produced increases, wider
High contrast is directly related to number of photoelectric interactions
The 10kvp guideline for kilovoltage is true in the range of 60-80kVp
An image contrast decreases, the number of densities in the image increase with more gray tones/densities
Wide exposure latitude shows long scale of contrast, creating a greater margin for error true
the relationship between kVp and density is described as direct, but not proportional
The original technique is 30mA @ 80kVp. What will produce a rad with twice the IR exposure/film density. 30mas @90 kvp 60mas @ 80kvp
How does kvp influence rad density? Sets penetrability of the photons in the beam
Low kvp creates ____ contrast increased
Low kvp creates ____ shades of gray few
Name a set of exposure factors that would provide an image with higher contrast than that produced by 12mas @92kvp but maintains the original density/level of exposure? 24mAs@78kvp
The usage of high kVp techniques would result in lower patient dose, decreased contrast and less scatter fog
What effect does beam penetration have on rad contrast? Increased kvp will decrease contrast
Image density is a product of intensity x duration of exposure is a definition of reciprocity law
The relationship of mA and time to maintain image density is directly proportional false
A disadvantage or limitation of high mA exposure is usage of a large focal spot
mAs affects visibility of detail False
What happens to patient doseage as the mAs increases? Increases
The relationship between kVp and contrast is inverse
What interaction produces a longer scale of contrast due to a high level of scatter from increased beam penetration? Compton
What definition describes body habitus? Variations in the shape of the human body
The relationship of mAs and kVp to maintain the level of exposure/film density is Inverse
Low kVp results in ____ kinetic energy of electrons reduced
The NCRP recommends a minimum total filtration value of ______ mm Al/Eq for imaging at 70kVp or greater 2.5
What influences the production of scattering radiation? Level of kvp, tissue thickness, field size of radiation
Compton becomes the dominant interaction at ____kvp 80
Which cast material of normal thickness requires only a doubling of mAs? Dry plaster
An increase in kilovoltage applied to the xray tube increases the exposure rate
Name an example of a compensating filter Wedge filter
Identify the purpose of a compensating filter Creates uniform image density
The standard protective filter material used in diagnostic radiology is aluminum
A long leg exam is ordered and the wedge filter is routinely used. The thin portion is placed at the proximal or hip end
What effect does the addition of protective filtering have on the average energy of photons in the primary beam Increases the average energy
Photons emerging from a properly filtered diagnostic unit are homogenous since they have the same energy level false
Which material requires a 2 times increase in mAs and an increase in kVp? wet plaster
Whether a fiberglass or plaster cast is applied, image contrast decreases
Filtration is the process of filtering undesirable _______by the insertion of absorbing material into the primary beam low energy xray photons
Filtration at the required diagnostic (>70kVp) minimum removes a portion of the useful beam True
Which is the following is affected by half-value layer? Patient exposure
total filtration is equal to the sum of _______filtration inherent and added
Name one factor which would require the technologist to change AEC sensor selection disease
Digitizing the light signal from the photomultiplier tube means assigning a numerical value to each light photon True
In CR imaging, images have increased contrast resolution along with increased spatial resolution True
Grid ratio determines the maximum angle by which a scattered photon can pass through the lead strips True
What artifact may be prevented by substituting a multi-hole grid for the standard linear grid when digital imaging is utilized? Grid lines
A low ratio grid compared to a high ratio grid will absorb less scatter radiation, produce a longer scale of contrast, require less exposure for a given density
the efficiency of a grid is its ability to remove scattered radiation which is based on grid ration and grid frequency
Using an out of range SId with a linear focused grid results in a loss of image density on the outer edges
Angulation of the beam with a linear, focused grid may be done with the long axis
Grid movement during the exposure serves what purpose? blurs grid lines
If an image taken with a 12:1 linear focused grid with 100 lpi exhibits a loss of density at the internal edges. It is because the grid is upside down
the majority of scattering energy is produced in the patient
the patient has an imapact on all the properties that affect a balanced image, such as IR exposure/density, contrast/dynamic range, resolution and distortion True
The ____ the body part, the _____ the primary beams attenuation thicker, greater
Bone produces
Created by: omichaele