Kahoot - Digital Image Acquisition Pt II

The digital image acquisition system is best described as which combination?

Image receptor & processing computer

Which characteristic describes the ability to detect small amounts of radiation?

Sensitivity

A more sensitive imaging system generally requires what?

Less exposure

Dynamic range is the range of what values available for image formation?

Pixel values

Which process can adjust the default dynamic range?

Equalization (DRC)

Spatial resolution is the ability to display small pixels as what?

Sharp image detail

Contrast resolution describes the ability to distinguish what?

Different tissues

In a CR reader, sampling frequency increases when the distance between samples does what?

Decreases

In a DR detector, sampling frequency depends mainly on what?

Del Pitch

Del pitch is measured from the center of one del to what point?

The center of an adjacent del

What happens to spatial resolution as pixel or del size becomes smaller?

It increases

What is the minimum number of pixels needed to form one image detail?

Two

The number of resolvable details is approximately what fraction of the available pixels?

One-half

Which unit is commonly used to measure spatial frequency?

Line-pairs per millimeter

A pixel width of 0.1mm provides a maximum spatial frequency of about what?

5 LP/mm

A line pair contains which two components?

One light and one dark line

Which formula estimates maximum spatial frequency from pixel size?

1/(2xPixel Size)

For a hardware matrix, del or hardware-pixel size is generally what?

Fixed

Why is inherent DR detector sharpness consistent?

Del size is fixed

Typical DR del sizes in the presentation range from approximately what?

100-200 microns

A 100-micron del produces a spatial frequency of about what?

5 LP/mm

For the same model of LCD monitor, a larger screen generally has what?

More hardware pixels of the same size

Collimating a DR exposure changes the displayed field of view but does not change what?

Del size

A soft matrix differs from a hardware matrix because its pixel size can be what?

Variable

In a CR reader, changing the laser-beam width can change what?

Pixel size

For a fixed image area, increasing matrix size causes soft pixels to become what?

Smaller

Excessive monitor magnification can make the image appear what?

Pixelated

As more zoom is applied to a displayed image, sharpness generally does what?

Decreases

A fixed-matrix CR system uses what across diffferent IR sizes?

The same number of pixels per row

In a fixed-matrix CR system, which IR size generally provides better sharpness?

Smaller IR

Most modern CR systems maintain consistent sharpness by using what approach?

Fixed sampling

The soft-pixel size formula is FOV divided by what?

Matrix dimension

Ultimately, sharpness is determined mainly by the size of what?

Dels or pixels

CR and indirect-conversion DR phosphors first convert x-rays into what?

Light

Which efficiency describes how well a phosphor captures incoming x-rays?

Absorption efficiency

A reflective backing in a CR plate primarily improves which efficiency?

Emission efficiency

Compared with direct-conversion DR, indirect-conversion DR generally requires what?

Less technique

Why does the direct-conversion DR generally provide higher spatial resolution?

It avoids light dispersion

Which receptor type has the highest typical DQE listed at 70 kV?

Indirect-Conversion DR

What does a 75% fill factor mean?

75% of the del detects radiation

A higher fill factor generally improves contrast resolution and what?

Signal-to-noise ratio

If del size decreases while TFT and capacitor size stay fixed, fill factor does what?

Decreases

The Nyquist theorem says sampling frequency must be at least how many times image frequency?

Two times

Insufficient sampling of high-frequency signals produce which artifacts?

Aliasing or Moire patterns

Which situation can create aliasing?

Using a stationary low-frequency grid

Which action helps prevent grid aliasing?

Use a higher-frequency grid

Which artifact is more commonly associated with DR than CR?

Electronic mottle

A ghost image on a CR plate most likely results from what?

Incomplete erasing

An artifact appearing on images from several different CR cassettes most likely comes from what?

The CR reader

Dust on CR reader optics can delete an entire line, causing what?

Line dropout