homework 7 review

Question 1

A combination of rows and columns (array) of pixels is called a

Answer 1

matrix

Question 2

A method of describing the strength of the radiation exposure compared with the amount of noise apparent in the digital image

Answer 2

signal to noise ratio

Question 3

An example of a scintillator used in an indirect conversion detector is:

Answer 3

gadolinium oxysulfide and cesium iodide

Question 4

Based on the histogram analysis, consistent image brightness is accomplished through:

Answer 4

automatic rescaling

Question 5

true/false:
Bit depth is determined by the matrix size.

Answer 5

false; bit depth is determined by the analog to digital converter (ADC)

Question 6

DR imaging systems briefly store the electrical charge in the

Answer 6

TFT (thin film transistor array)

Question 7

If the matrix size is increased for a fixed field of view (FOV), the pixel size is ___________

Answer 7

decreased

Question 8

Immediately before leaving the CR reader unit, the IP is exposed to:

Answer 8

intense white light

Question 9

Increasing the number of line pairs per millimeter resolved in the imaging system results in:

Answer 9

increased spatial resolution

Question 10

Overexposing a digital image receptor may result in:
-high SNR
-visible quantum noise
-increased patient exposure

Answer 10

high SNR and increased patient exposure

Question 11

Pixel bit depth is determined by the

Answer 11

ADC (analog to digital converter)

Question 12

The histogram is a graphic representation of the ______________

Answer 12

range and incidence of pixel values

Question 13

The distance between the analog points being sampled is the

Answer 13

sampling pitch

Question 14

The ability of the detector to accurately capture the variety of photon intensities in the remnant radiation is

Answer 14

dynamic range

Question 15

true/false: The DR system does not require a separate reader unit.

Answer 15

true

Question 16

The DR system sends the digital signal __________________

Answer 16

directly to the computer.

Question 17

The CR phosphor layer is composed of ________________ with ___________

Answer 17

barium fluorohalide, europium

Question 18

The numerical value indicating the level of radiation exposure to the digital IR is the:

Answer 18

exposure indicator

Question 19

This material is composed of barium fluorohalide and makes up the primary component of the CR IP

Answer 19

photostimulable phosphor

Question 20

What factors may influence the exposure indicator (EI)?
-collimation
-focal spot size
-centering

Answer 20

collimation and centering

Question 21

What is the term generally used to describe the emission of light from a substance as the result of stimulation by radiation?

Answer 21

luminescence

Question 22

What type of image receptor converts the exit radiation into electrical charges and stores them before readout and digitization?

Answer 22

DR

Question 23

Which of the following is not a component of a flat-panel detector?
-glass substrate
-TFT array
-x-ray converter
-phosphor layer

Answer 23

phosphor layer

Question 24

what is the sequence of events for CR reading unit?

Answer 24

1. Stored energy is released as visible light,
2. PMT converts light energy to electrical signal
3. analog electrical signal is sampled and digitized

Question 25

With CR, trapped electrons are
-proportional to the exit exposure intensity
-released during readout stage
-in a lower energy state

Answer 25

-proportional to the exit exposure intensity
-released during readout stage