DIGITAL EXAM 1 122

CR technology uses

Reusable imaging plates, monoenergetic laser stimulation, reader assemblies

When setting kVp levels using DR technologies, it is important to understand that

ALL OF THE ABOVE higher kVp values produce a more narrow histogram kVp levels should not exceed 80 kVp for non grid radiography when scatter ratios reach 50 percent or greater, radiographic grids should be used

The luminescence of blue-violet light from a CR fluorohalide, due to laser stimulation

Is proportional to the x-ray energy exposure

7 Imaging plate layers

▪ Top protective layer ▪ Phosphor layer ▪ Conductor layer ▪ Support layer ▪ Light shielding layer ▪ Bottom protective backing layer

Objectionable quantum noise on an image that makes its acceptance marginal, generally indicates an underexposure of

25 percent

With a variable-kVp exposure technique system, the threshold kVp is typically set at

30 kVp

An x-ray exposure taken at 80 kVp has an average energy of

35 keV

In CR the latent image consists of millions of

F-centers and electron holes

A CR imaging plate that has been grossly overexposed can demonstrate __________ if the erasure process is incomplete

Ghosting

Pixel bit depth determines

Gray shade levels

As you complete your daily, late afternoon duties as a radiographer, you notice a CR cassette that was exposed earlier in the morning. When you processes the cassette in the reader, the resultant image will demonstrate

High levels of quantum noise

In CR technology, preprocessing of data includes

Histogram analysis, grayscale analysis, exposure data recognition

The fluorohalides used in CR are predominantly composed of

Bromide

Select the TRUE statement regarding computer radiography

CR imaging plates are very sensitive to post-exposure radiation

The area of a DR detector DEL that is insensitive to x-ray exposure.

Consists of DEL electronics.

To reproduce an analog signal with truer representation and accuracy, the most effective method to do so is

Increase the sampling rate to a value greater than the Nyquist value

All of the following are true of Moire effect EXCEPT

It is most likely to occur with DR technology, particularly amorphous selenium

Underexposure using DR detectors will result in A. less spatial resolution. B. photon saturation. C. quantum noise. D. electronic noise.

Quantum noise

Readout of CR data from the imaging plate is a line-by-line process which creates a

Raster pattern

As a radiographer you are looking at an image you had just taken on the review monitor the image looks marginally noisy youre next step should be to

Refer to the exposure index # to confirm image appearance

As a radiographer, you are using Dr systems that displayed EI# as part of the DICOM header the EI# are calculated as directly proportional and linear to the exposure

Repeats the exposure at 85 kvp @ 20 mas

In CR, pixel pitch is dependent upon

Sampling frequency

in a digital detector the term fill-factor refers to the

Size of the DEL

The tendency of technologists to use more exposure than needed, and allowing computer rescaling to compensate for it, has lead to

dose creep

In the technology of CR, the latent image is actually

electron "holes" in Europium

When adding annotation to a digital radiographic image, it is important to remember that

electronic annotation for patient laterality is unacceptable

Elimination of extraneous light from the edges of a digital radiographic image, is achieved through

electronic masking

a key feature of DR/CR technologies is the increased sensitivity of the receptor to a wider range of remnant radiation energies, when compared to conventional film- screen systems. This is referred to as

low contrast resolution

Computerized digital images consist of a ________ of picture elements, each with a video display value or gray shade.

matrix

The component that converts light to an electronic signal in a digital detector is the

photoconductor

Computed radiography uses (a) _____ for latent image formation.

photostimulable phosphor

With digital technologies (DR/CR), perhaps the single-most important consideration when using this technology is

the total amount of exposure incident upon the detector

a major distinsction b/n DR and CR receptors is that

*CR requires particular attention to placement of the anatomy on the receptor *DR is not affected by collimation symmetry *The latent image in CR is time-sensitive

Digital radiography first began to be used in clinical settings in the _____.

1980's

Fixed kvp techniques systems require

An optimum threshold kvp

In computer radiography, is the reader scanning frequency and the radiographic grid frequency are similar and in the same orientation, what is likely to occur?

Moire effect

The response to x-ray exposure with CR imaging plates is

Nonlinear

Computed radiography is also referred to as

PSP technology

Underexposed radiographic image demonstrates

Photon starvation

Positioning of an AP wrist protection off center using a CR receptor, will likely lead to

Preprocessing errors of the data, an incorrect histogram analysis, sub optimum image quality

When using CR technology, it is important to remember that

The IP is extra sensitive to exposure after the initial x-ray exposure, the IP will lose about 25% of its signal in 8 hours if not processed, the IP is very sensitive to scatter, making grids very important ALL OF THE ABOVE

With digital detector technology, the traditional rules of exposure and image quality do not necessarily apply completely. One of these rules is that

The amount of scatter formation is primarily a function of mAs rather than kVp

What is the relationship between CR plate size and spatial resolution?

The best CR spatial resolution is achieved with the smallest size CR plates

With digital detector technology, the electronic signal is:

The latent image An analog signal A data set of signal intensities (all of the above)

When using a Fuji CR system in the fixed mode of operation

The system will not correct for exposure inadequacies and adjust for density problems, your exposure techniques must be accurate, similar to film/screen technology BOTH B AND C

DR panels that are connected to the radiographic unit with a "hard wired" connection cable

are considered to be "tethered"

Select the TRUE statement with regard to complementary metal oxide semiconductor (CMOS) technology:

They are not widely used with flat panel DR technology

A common feature between indirect and direct DR technology is

Thin film technology (TFT)

In direct digital detectors, the electronic readout of signal is accomplished by the

Thin film transistor (TFT)

True/False Csl/CCD is a indirect DR process by which x-rays are converted first to light and then to electric signal.

True

All of the following are related EXCEPT A. Automatic B. Variable C. Semi- Automatic D. Fixed

Variable

The purpose of a charge couple device (CCD) when used with a DR detector is to

act as a photoconductor collect the light from the scintillator and convert it to the electrons (Both B and C)

Extraneous information that appears on a medical image, that does not represent the patient and their medical condition, is referred to as

an artifacte

Of the choices below, select the DR panel that would provide the highest spatial resolution. a. DEL size 200 microns, 75% fill factor b. DEL size 125 microns, 95% fill factor c. DEL size 110 microns, 75% fill factor d. DEL size 140 microns, 95% fill factor

b. DEL size 125 microns, 95% fill factor

A radiographic image that demonstrates image receptor electronics on the final image superimposed over patient anatomy is likely the result of

backscatter radiation

DR panels have published specifications from the manufacturer that outline performance conditions. DR panels are particularly vulnerable to

bodily fluids

Indirect DR uses ________ as the photoconductor material. a. calcium tugstate b. amorphous selenium c. amorphous silicon d. gadolinium oxysulfide

c. amorphous silicon

Indirect DR detectors employ the use of _____________ as a scintillator. a. cmos b. zinc cadmium sulfide c. cesium iodide d. ccd

c. cesium iodide

Conventional x-ray tubes and cassettes are used with _____ radiography systems

computed

DR detector element saturation can result in image

data drop

Extreme overexposure to a DR detector can result in

detector DEL saturation

the calculation of exposure index values can vary between manufacturers of DR/CR technology. the AAPM has established a scale of exposure ranges known as a(n) ___, that accounts for these variations in calculations

deviation index (DI)

The total amount of clinically significant diagnostic image on a medical image is referred to as

diagnostic yield

The relationship between the detector "fill factor" and spatial resolution is:

direct

A DR detector that is integral to the x-ray system means that the detector

is built in to the design of the x-ray equipment and the radiographer cannot access it.

Auto-detection technology with a DR panel

is often referred to as a trigger panel

CR systems acquire clinical information by

laser scanning a PSP plate

The final appearance of a digital image in terms of brightness and contrast is principally due to

the application of a look up table

Which of the following factors would decrease the remnant radiation exposure to a dr detector

using a 8" air-gap.

Essential to ALARA compliance is

using accurate exposure techniques based upon patient measurement

DR and CR image receptors

work well with automatic exposure control.