Ch22

Computed radiography is also referred to as

PSP technology.

Flat panel technology.

Laser-stimulated technology.

Receptor technology.

CR technology uses

Reusable imaging plates.

Monoenergetic laser stimulation.

Reader assemblies.

All of the above.

The fluorohalides used in CR are predominantly composed of

Cesium iodide

Amorphous silicon

Bromide

Iodide

CR systems acquire clinical information by

Laser scanning a PSP plate.

Gathering light from a scintillator.

Direct digital transformation of x-ray photon energy to a selenium plate.

Capturing light from a charged couple device (CCD).

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

Row

Matrix

Column

Pixel

When using CR technology, it is important to remember that

The IP is extrasensitive to exposure after the initial x-ray exposure.

The IP will lose about 25 percent of its signal in 8 hours if not processed.

The IP is very sensitive to scatter, making grids very important.

All of the above.

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

24 keV.

35 keV.

60 keV.

80 keV.

In the technology of CR, the latent image is actually

Sensitivity specks in the barium fluorohalide.

Free electrons in the amorphous silicon.

Electron “holes” in Europium.

The light from the phosphor following laser excitation of the reader assembly.

In CR technology, preprocessing of data includes

Histogram analysis.

Grayscale analysis.

Exposure data recognition (EDR).

All of the above.

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

A. Exposure techniques are variable and adjustable by the computer to adjust density and contrast.

B. The system will not correct for exposure inadequacies and adjust for density problems.

C. Your exposure techniques must be accurate, similar to film/screen technology.

D. Both b and c.

All of the following are true of the Moire effect EXCEPT:

It results from a conflict in spatial frequencies between the grid frequency and laser scanning frequency.

It produces useless diagonal dark lines across the finished image.

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

It is eliminated with ultra-high grid frequencies 178–200 lpi.

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

Is proportional to the x-ray energy exposure.

Is inversely related to x-ray exposure.

Is not related to the x-ray exposure.

Is directly related to the rescaling process.

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

Detector array grid.

Raster pattern.

A series of sensitivity specks.

Linear array.

In CR the latent image consists of millions of

Sensitivity specks.

Detector elements.

F-centers and electron holes.

Voltage gates.

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

Quantum noise.

Ghosting

Increased brightness.

Decreased contrast.

In CR, pixel pitch is dependent upon

DEL size.

Viewing monitor size.

Laser energy wavelength of the reader.

Sampling frequency.

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

Increase the sampling rate to at least the Nyquist value.

Decrease the sampling to ½ Nyquist.

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

None of the above.

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

Preprocessing errors of the data.

An incorrect histogram analysis.

Suboptimum image quality.

All of the above.

All of the following are related EXCEPT

Automatic

Variable

Semi-automatic

Fixed

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

Grid cut-off

Data drop

Moire effect

Nyquist errors

Select the TRUE statement regarding computer radiography (CR).

CR imaging plates are very sensitive to post-exposure radiation.

Radiographic grids are of little value with CR, due to histogram analysis.

CR plate sampling rates determine image brightness.

Running a CR plate in the fixed mode for a Fuji system, requires precise positioning.

Pixel bit depth determines

Spatial resolution

Gray shade levels

Pixel dimension

Image brightness

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

Smaller CR plates deliver less resolution due to a lower sampling frequency

Larger CR plates deliver better spatial resolution

Plate size and image resolution have no relationship

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

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 process the cassette in the reader, the resultant image will demonstrate

High levels of quantum noise.

Decreased brightness.

A loss of spatial resolution.

Acceptable image quality.

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

Logarithmic

Nonlinear

Linear

Similar to photographic film

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