RADI 143 - Exam 4

The KVP is held constant for a given range of subject densities and contrast while the mass

is varied to achieve the appropriate image density describes

fixed KVP systems

advantages of fixed KVP systems include

decrease patient dose, increases tube life, consistent contrast levels

The maximum KVP level that will produce images with appropriate contrast that are consistently within acceptable limits describes

optimal KVP

what is the optimal KVP range for skull work

85 kvp

The systems advantage is that it permits small incremental changes an exposure for the body part being examined

variable KVP systems

from earlier days, it was common to change KVP and increments of ___ kvp for every ___ cm

2,1

most medical facilities use ___ kvp over ___ kvp charts

APR stands for

Anatomically Programmed Radiography

which system eliminates the need to set an exposure time

AEC

what does OD stand for

optical density

a density factor of +1 is equivalent to ___ in relative exposure

25% increase

when using AEC, what results in an increased repeat rate

Poor positioning skills

grayscale bit depth contains the number of shades of a gray allowable and one pixel. The equipment can have bits that range from ___ bits - ___ bits

8-32

if the field of view (FOV) remains the same; then as the matrix size increases, the pixels get ___, and the image becomes ___

smaller, sharper

What's a Instagram has been determined, a histogram analysis is been performed within the computer to determine what two things

values of interest and exposure indicator

A wide histogram will have what type of contract

high

The LUT is applied to the image after the histogram is made in the histogram analysis is performed. What does this do to the image

adjusts contrast

if an image is showing only few densities on the monitor, it is said to have high contrast. What type of window width will have high contrast

narrow

which spacial frequency filter removes or suppresses low spatial frequency from the image, resulting in an increase of contrast and producing a sharper image

High-pass Filtering/Edge Enhancement

an increase in signal to noise ratio, or a higher SNR indicates what

little noise

what is the only way to decrease quantum mottle noise

repeating the image with increased technical factors

DR systems have DQE's of ___ - ___ % efficiency

30-70

A device with 100% efficiency of converting incoming data to the output viewing device has a DQE of ___ meaning there is ___ loss of information

1, no

The comparison between the actual exposure and the proper exposure received by the image detector is known as

deviation index

The exposure sensitivity of an imaging detector ranges from

.1 mR - 100 mR

Fuji, Konica and Phillips manufactures have a sensitivity number or 's' value which demonstrates the exposure to the imaging plate. What type of relationship does the S value have in regards to exposure

as exposure increases, the S value decreases, inverse

which of the detector configurations creates the image without a scintillator

direct conversion

what is the active layer of the PSP plate in computed radiography

phosphor layer

in CR, when does the photo stimulated luminescence or PSL occur

I a peso pitch she gets smaller, the ___ the special resolution

greater

once the Layton image is captured by the PSP play, it is fed through the processor and scanned line by line in what pattern

raster pattern

in CR, pixel pitch is determined by the size of what

sampling or Nyquist frequency

A grossly overexposed plate may not erase completely. What artifact results from this on the next image

ghosting artifact

The latent image in computed radiography is formed where

europium phosphor sites

The late imaged on a CR plate will lose about how much of its energy and how many hours

25%, 8 hours

what is the most common type of CR phosphorus

barium fluorohalide bromide with europium activators & barium fluorohalide iodide with europium activators

in PSP technology, what does a photo detector do

converts light into electronic signal

The process that will determine the brightness levels or grayscale for the pixels is

quantification

segmentation (through carestream manufacturers) is also known as what?

exposure recognition

causes of histogram analysis air include

Poor collimation, increased or decreased attenuation located in the body where it's not normally located, too much collimation and prosthetic devices included or other parts with large density differences

in DR, the pixel pitch is determined by the size of what

detector element

each image will generate its own specific ___ using the image data from within the collimated edges. This allows the system to find the useful signal

histogram

grid cut off and digital radiography will have what type of appearance

Poor spatial resolution, poor density or brightness, poor contrast

and certain detectors of DR, this is the last step of the x-ray conversion. This collects electric charges to produce an electric readout. This information is collected in a type of matrix known as a ___ containing ___

TFT array (or active-matrix array) containing detector elements (DELs

Direct conversion detectors use

Amorphous Selenium

which detector uses this conversion process? X-ray strike the scintillator, then the light is optically coupled to special sensors like the lenses in optic fibers. then the light can be converted into an electric charge and sent to the computer to be displayed

indirect converison

which digital artifact is caused by dust or foreign objects on the IP

white spots

And digital radiography, and underexposed image will show ___ even though densities adequate. An image that is overexpose will tend to suffer from ___ contrast

quantum mottle, low

A scintillator can be made using which types of material