3

Question 1

HISTOGRAM ANALYSIS ERROR

Image recognition is accomplished
through mathematical computer
algorithms and errors in the selection
of the anatomic part/projection can
cause inappropriate processing
○
Remedy = postprocess, unassign
★ Grayscale map — desired values for
specific procedures

Answer 1

INCORRECT ANATOMIC MENU SELECTION

Question 2

desired values for
specific procedures

Answer 2

Grayscale map

Question 3

Automatic rescaling will fail if exposure
field edges are not detected or if there
is unexpected material, such as metal
within the field of exposure
○
Remedy = postprocessing

Answer 3

UNEXPECTED MATERIAL IN DATA SET

Question 4

means that beyond a certain
exposure level, a large number of the
pixels will be at the maximum digital
value (black)
★ Exposure Indicator Index

Answer 4

SATURATION / OVEREXPOSURE

Question 5

Brighter image + presence of quantum
noise/mottle
○
Grainy appearance
★ If the detector is underexposed due to
inadequate radiographic technique
factors, even though the image can be
amplified and rescaled to present a
good greyscale rendition, the quantum
mottle in the image is likewise
amplified, resulting in a noisy and grainy image

Answer 5

UNDEREXPOSURE

Question 6

Purpose of ____ is to
identify the appropriate raw data
values to be used for image gray scale
rendition

Answer 6

exposure field recognition

Question 7

Inclusion of the off focus radiation and the scatter outside the collimation will widen or skew the histogram.

Answer 7

Exposure field recognition error

Question 8

Reasons for Field Detection Errors:

Answer 8

Irregular collimation shapes
Multiple image on a single
plate
Collimating into a corner plate
3 edges of collimation on the
plate
Not centered to the plate

Question 9

Images are produced with uniform
brightness and contrast, regardless of
the amount of exposure used to
acquire the image

Answer 9

AUTOMATIC RESCALING

Question 10

• Accumulated background radiation
• In CR, If PSP storage plates are stored for extended periods of time, artifacts will most likely occur.

Answer 10

Low Intensity Radiation
Response

Question 11

Beam Restriction / Collimation
• Inappropriate collimation will cause histogram to widen. Widening of histogram will cause anatomic values of interest to scale in appropriately.

Answer 11

scatter control

Question 12

In CR, it provides an indication of the amount of radiation reaching the detector as a result of exposure technique - Exposure indicator.

Answer 12

exposure field recognition

Question 13

appears on the image and provides the technologist with the visual feedback regarding radiation exposure of patient.

Answer 13

Exposure Indicator/Index

Question 14

Multiple exposure fields is ability of CR to acquire multiple images on one imaging plate, necessitating strict alignment rules.

Answer 14

Exposure Field Recognition

Question 15

Most common reason for Histogram Analysis error. The inclusion of the off focus radiation and the scatter outside the collimation will widen or skew the histogram.

Answer 15

Exposure Field Recognition Error

Question 16

Failure of Automatic Rescaling
will result in a

Answer 16

dark, light, or low contrast image.

Question 17

Impact of accumulated background Radiation
In __ this is not a problem because the __ detector is automatically refreshed prior to exposure.
In __ It PSP storage plates are stored tor extended periods of time, artifacts will most likely occur.

Answer 17

DR, CR

Question 18

are x-rays that travel in a different direction after exiting the patient body.
With the increased sensitivity of the PSP plate to low intensity radiation. Scatter control becomes an important consideration.

Answer 18

scatter radiation

Question 19

produces fog and therefore
increases density but reduces contrast

Answer 19

Scatter Radiation

Question 20

Factors affecting Scatter Radiation

Answer 20

1. KVP
2. Field size
3. Patient thickness

Question 21

It is critical for optimal image acquisition.
Collimation limits the irradiated volume and reduces undercutting. It also defines the field of view.

Answer 21

beam restriction/collimation

Question 22

Beam restriction / Collimation
By collimating appropriately, a smaller area of patient’s tissue is exposed, thereby reducing patient dose and minimizing the production of scatter radiation, which also minimizes the amount of scatter radiation reaching the IR.

Histogram analysis and initial image processing
depend on proper pre-exposure collimation.
Inappropriate collimation will cause histogram to widen. Widening of histogram will cause anatomic values of interest to scale inappropriately.

Question 23

Device that absorbs scatter
radiation before it reaches the film

Answer 23

GRID

Question 24

___- the number of grid strips or
grid lines per inch or per cm.
___- The height of grid strip divided
by the thickness of the interspace material

Answer 24

Grid Frequency,

Grid ratio

Question 25

grid When selecting the appropriate grid for use with CR, the grid frequency is important because the image is scanned line by line. If the grid used has a frequency near the scan frequency and the grid strips are oriented in the same direction as the scan, one can observe the moire pattern.

Question 26

Compton interaction is higher in

Answer 26

tissues with more water content, such as the abdomen

Question 27

Proper collimation ○ Collimation is used to reduce scattered radiation ○ The system recognizes exposure fields with 2 or 4 collimated sides. If collimation is improper, it will interpret the entire image receptor as the exposure area, since it detects all four edges of the IR instead of the actual collimated field. ★ 2 in 1 is used to limit the processing time