digital imaging unit 2 test

which imaging system has a higher DQE

DR

images having higher spatial resolution are composed of

a greater number of pixels

a bit depth of _____ bits produces an image with the greatest contrast resolution

higher like 16

a high signal to noise ratio SNR provides an image with

higher spatial resolution

which of the following would improve digital image quality

large matrix and increased pixel density

which one of the following is used to extract the latent image from the photostimuable phosphor plate

laser light

when comparing DR to CR, DR produces

lower pt dose and less spatial resolution

the arrangement of pixels in rows and columns is known as

matrix size

the process of assigning a numeric value to each pixel to represent a gray tone is called

quantization

which of the following is not a step that is required to transform an analog image into a digital image

ranging

the purpose of a capacitor, such as those used in DR flat panel detectors are used to

store electric charges (electrons)

the image on a photostimuable phosphor plate is not permanent and will fade at a rate of about

25% within 8 hours of the exposure

if the desired spatial resolution for an image is 20lp/mm what must the sampling frequency be

40 lp/mm

this converts xrays to electrons in a direct conversion flat panel detector

amorphous selenium

a fill factor of 80% in direct or indirect digital radiography means that

20% of the pixel area is occupied by the detector electronics with 80% representing the sensing area

the greatest modulation transfer function number is

1

when the CR casette is placed in the reader, arrange the following in the proper sequence of processing the latent image

1. the phosphor plate is scanned with a laser light 2. light guide collects light 3. photomultiplier tube produces an analog signal 4. ADC convers the analog signal to digital signal 5. erase the imaging plate

which one of the following matrix sizes will be able to display the highest spatial resolution

1024x 1024

the analog signal is changed into a digital signal in the

ADC

an image receptor with a high detective quantum efficiency compared to an image receptor with a low DQE would result in

a lower pt dose

the purpose of a "scintillator" in a flat panel receptor is to

absorb xray photons and emit light photons

the gray scale value in the pixels is closely related to the

attenuation properties of the amount and density of the tissue

in CR what is the name of the photostimuable phosphor in the imaging plate

barium fluorohalide

contrast resolution of a CR/DR image is determined by the ______ of the system

bit depth

the number of visible shades of gray in a digital image is determined by _______

bit depth

the xray scintillator layer used in indriect flat panel digital detectors is usually either _____ or ______

cesium iodide, gadolinium oxysulfide

which of the following are found in the detector element of a flat panel detector

charge collection area, capacitor, thin film resistor

the type of image receptor that uses a photostimulable phosphor to acquire the latent image

computed radiography

the smallest exposure change or signal difference that can be detected is a definition for

contrast resolution

At the end of an image extraction cycle, the photostimulable phosphor plate (PSP) is erased by exposing it to intense: a. red light b. laser beam energy c. x-ray energy d. white light

d. white light

which of the following measures the efficiency of a system to convert the xray input signal into a useful output signal

detective quantum efficiency

spatial resolution in a flat panel receptor primarily is controlled by the size of the

detector element (DEL)

the flat panel detector matrix is made up of rows and columns of

detector elements (DELs)

an image formed by recording discrete signals is known as _______ signal

digital

when a greater number of samples are taken from the image receptor signal, this indicates that the

digital data more closely resembles the original signal

which one of the following is defined as the range of exposures that may be captured by a detector

dynamic range

what represents the latent image in a photostimuable phosphor CR system

electrons trapped in conduction band

What is the rule for erasing the fog, caused by the background radiation, from the imaging plate

erase the imaging plate if it has been unused for more than 48 hours

what directly influences the number of electrons collected in a detector element (DEL) of a flat panel detector

exposure to image receptor

to reduce the appearance of grid lines and the moire artifact, grids used in digital imaging should have a high

grid frequency

the principle effect of the use of an insufficient amount of radiation when performing any type of digital radiographic examination is a/an

increase in the amount of quantum mottle (noise) on the image

as the fill factor in the DEL decreases in size, patient dose will need to be

increased

a major advantage of digital receptors over analog receptors is

increased contrast resolution

which of the following will improve the quality (spatial resolution) of the digital image

increased sampling frequency and decreased sampling pitch

thin film transistors are found in which type of digital imaging system

indirect and direct flat panel detectors

with DR image receptors, CCD and complementary metal oxide semiconductors are used in

indirect conversion flat panel detectors

__________ is a measurement of the ability to transfer contrast at a particular resolution from the object to the image receptor

modulation transfer function

as SNR decreases

noise in the form of graininess increases

the highest spatial resolution that can be recorded, and is controlled by pixel pitch, is known as

nyquist frequency

To prevent a moire pattern in your CR digital image, it is best to have the grid lines running _______ to the direction of the laser beam.

perpendicular

the layers of a CR imaging plate include

phosphor, reflective, protective

a device contained within CR, readers that functions to collect, amplify, and convert light released by the photostimuable phosphor into electrical energy is called a

photomultiplier tube

pixel is a shortened term for

picture element

the smallest area represented in a digital image is the

pixel

________ is defined as the number of pixels/mm

pixel density

_______ is defined as the measurement from the center of one pixel to the center of the adjacent pixel

pixel pitch

__________ is the measurement from side to side of the pixel

pixel size

in CR imaging, the sampling frequency of an imaging system determines the

pixel size

contrast resolution is a digital systems ability to

show small differences in gray levels

_______ is defined as the sharpness of the structural edges recorded in the image

spatial resolution

digital imaging systems have a wide dynamic range

true

the higher the contrast to noise ratio, the higher the contrast resolution

true

within the histogram the area that is used to locate the minimum and maximum values of the pixels for the body part is called the

value of interest

a larger image matrix

will increase digital image resolution

a smaller pixel size

will increase digital image resolution

a smaller pixel pitch

will increase the digital image resolution