Final - Part 2

Question 1

The % of the pixel in a digital IR that is sensitive to x-rays is known as?

Answer 1

Fill factor

Question 2

How is fill factor related to spatial resolution?

Answer 2

Increased fill factor = increased spatial resolution.

Question 3

How do you determine pixel sixe?

Answer 3

FOV / Matrix

Question 4

What is bit depth?

Answer 4

of grey shades available. Total # of brightness levels

Question 5

The digital image is composed of rows & columns called a?

Answer 5

Matrix

Question 6

Each ___ in a matrix represents a visual brightness or density level. This brightness is reflective of the tissue characteristics.

Answer 6

pixel

Question 7

Steps of digitatl imaging:
1st step: ___ - the image is broken down into pixels.
2nd step: ____ - pixel brightness is measured.
3rd step: ____ - brightness levels are assigned a numerical value.

Answer 7

1 - scanning
2 - sampling
3 - quantization

Question 8

Each pixel corresponds to a 3D volume of tissue known as?

Answer 8

Voxel

Question 9

The # of pixels per mm in the image is known as?

Answer 9

Pixel density

Question 10

A greyscale bit depth of 12 produces how many levels or shades of grey?

Answer 10

4096

Question 11

To determine the # of pixels, multiply the # of rows by the # of columns. A matrix size of 512 x 512 has how many pixels?

Answer 11

262,144

Question 12

The overall dimension of a matrix is known as ___ which represents how much anatomy is included in the matrix.

Answer 12

FOV (Field of View)

Question 13

If the FOV stays the same & the matrix size increases, the pixel size?

Answer 13

Decreases

Question 14

If the matrix stays the same & the FOV decreases, the pixel size?

Answer 14

Decreases

Question 15

The smaller the pixel size the better the image quality, therefore the pixel size determines?

Answer 15

Spatial resolution

Question 16

A histogram is a representation of the imaged area broken down into pixels based on the min & max values.
The x (horizontal) axis represents _____.
The y (vertical) axis represents _____.
The system will determine the VOI or ____.
The S1 is the ____ signal & the S2 is the _____ signal.

Answer 16

x - specific exposure values captured by receptor.
y - frequency of specific exposure values.
VOI = values of interest
S1 - minimum
S2 - maximum

Question 17

The shape of the histogram corresponds to the specific anatomy & the technique that was used. The computer will try to “shift’ or rescale the histogram to be closer to the original or reference histogram. This is known as?

Answer 17

Histogram modification/stretching/rescaling.

Question 18

The histogram of the processed image is compared to a pre-existing histogram for the same body part in the ____. This applies the proper grayscale to the image by adjusting the contrast to the reference contrast levels to provide consistent images.

Answer 18

Look up table

Question 19

Histogram errors can be caused by the histogram not matching the parameters of the reference histogram, ____ recognition errors, inaccurate exposure #s caused by too much or too little ____, & increased or decreased attenuation by body parts.

Answer 19

field
collimation

Question 20

During pre-processing the system tries to determine the density values of densities w/i the collimated field versus outside of the collimated field for the correct histogram. This is known as?

Answer 20

Exposure Field Recognition

Question 21

Spatial resolution is increased w/
____ matrix size,
____ pixel size,
decreased (smaller) phosphor size,
____ laser beam,
____ pixel pitch,
____ DEL size,
____ fill factor, and
____ PSP.

Answer 21

increased (larger)
decreased (smaller)
smaller
decreased
smaller
increased
thinner

Question 22

The range of exposures that can be captured by a detector is known as?

Answer 22

Dynamic range

Question 23

A radiograph produced w/ an extreme level of overexposure might have an error known as ___.
While a radiograph produced in the lowest portion of the dynamic range might exhibit ____.

Answer 23

saturation artifact
quantum mottle

Question 24

The range of exposures that produce a quality image at an appropriate dose is known as?

Answer 24

Exposure latitude

Question 25

The dynamic range is ___ that the exposure latitude.

Answer 25

wider