Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Spring 2023 > Recorded Detail > Flashcards

Recorded Detail Flashcards

1
Q

March 13 = physics exam

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Recorded detail

A

detail definition or sharpness in film/screen radiography
Known as spatial resolution in DR
The sharpness of structure lines in a radiograph

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

4 factors affecting recorded detail

A

Geometric
motion
IR
Object

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Geometric factors

A

Focal spot size
SID
OID
Heel effect
Deal with the arrangement in space of xray beam, part being radiographed, and IR

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Motion factors

A

X-ray source
IR
Patient

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

IR factors

A

Film speed
Intesifying screen
Quantum mottle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Object factors

A

Size
shape

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Focal spot size

A

Smaller focal spot size, the greater the recorded detail and vice versa
Small focal spot range: 0.3mm to 1.0mm
Large focal spot range: 1.0mm-2.5mm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

2 ways to describe focal spot size

A

Actual focal spot size - the actail area being bombarded by electrons
Effective, apparent, projected, or nominal focal spot - the way the actual area appears from the perspective of the IR

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Line focus prinicle

A

effective focal spot will always appear smaller than the actual focal spot
Relationship between the actual and effective focal spot size is governed by this

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Size of affected focal soot is affected by 2 factors

A
  1. Size of actual focal spot - smaller the actual, smaller the effective
    Size of actual focal spot is governed by size of filament in cathode
  2. Anode angle - smaller the anode angle, smaller the effective focal spot size
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Dual focused xray tube

A

Required to give radiographer a choice of either a small or large focal spot,

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Advantages + disadvantages of focal spot size

A

Small - better detail
use at less than 50 mAs
Lower heat capacity
Reduces tube life
Large- Detail not as sharp
use at any mAs
Higher heat capacity
Increases tube life

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Effect of focal spot size on recorded detail

A

Umbra (shadow) – the distinctly
sharp area of a shadow or region
of complete shadow.
This will be the true image of the
object being radiographed.
Penumbra - the imperfect, unsharp shadow surrounding the
umbra.
It can also be referred to as
unsharpness, edge gradient or
geometric unsharpness.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Penumbra

A

As focal spot size increases, so does the size of the penumbra
Recorded detail decreases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Focal spot blooming

A

Over time or with increase in mA used, size of the focal spot can increase from its stated nominal value

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Focal spot size evaluation

A

to determine if focal spot blooming has occured

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Focal spot size testing can be performed by one of three devices

A

Pinhole camera - tiny hole of a specified shape is cut into a plate of metal allloy
Focal spot test tool - series of slits is radiographed, corresponding chart is used
Star or slit resolution patterns - chart if various shapes and/or lines that can
estimate focal spot size.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Effect of SID

A

Short SID’s will decrease recorded detail because the penumbra size increases
Long SID’s will increase recorded detail because penumbra is smaller
SID and recorded detail have a direct relationship

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Effect of OID

A

Larger OID will cause larger penumbra before reaching IR, thereby reducing recorded detail
Shorter OID will increase recorded detail
Inverse relationship for OID and recorded detail

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Calculating average penumbra size

A

penumbra = EFS x OID/SOD
SOD = SID-OID

22
Q

Anode heel effect

A

The penumbra is always
larger on the cathode side of
the x-ray field due to the
heel effect.
Therefore, recorded detail is
slightly better toward the
anode side

23
Q

Motion factors

A

Motion of patient, xray source, IR during exposure can cause motion blur
Motion blurs destroys recorded detail

24
Q

Patient motion

A

Common cause of motion blur
Minimized by:
Suspend respiration
Communicate clear instructions
Utilize short exposure times
Immobilize when necessary

25
IR factors
Film speed - faster speed, decreased recorded detail Intensifying screen - Faster speed will decrease recorded detail - Crystal size/shape: smaller size or columnar shape will increase recorded detail -Active layer: thinner layers increase recorded detail -Film/screen contact: bad contact reduces recorded detail Quantum mottle - causes blotchy appearance which reduces recorded detail
26
Quantum mottle
Speckled appearance caused by insufficient xray photons covering IR
27
Object factors - size
Thinner objects allow for a smaller penumbra than thicker objects Recorded detail is better with thinner object
28
Object factors - shape
Objects similar in shape to xray beam (cone-shaped) have smaller penumbra size than any other shape Results in better spatial resolution
29
Related terms
Visibility and resolution - not the same thing as recorded detail but are related
30
Visibility of detail
How well the radiographic image can be seen and affect mainly by optical density and contrast
31
Modulation transfer function
can be used to measure visibility of detail Numbers from 0 to 1 obtained using fourier analysis The closer to 1.0, better spatial resolution
32
DR image quality characteristics
MTF measures visibility of detail, which is clarity of the image DR systems should deliver a MTF of 30% at 2 lp/mm and 60% at 60% at 1 lp/mm
33
Resolution
Ability of an imaging system to deliver recorded detail, visibility of detail, and events happening in time 3 types of resloution: Contrast Temporal spatial
34
Contrast resolution
Ability of imaging system to distinguish structures that are similar in size or density as separate entities Also known as low contrast resolution Affected by contrast sensitivity of IR
35
Evaluation of contrast resolution
Use a scoring system from a phantom image
36
Contrast resolution and visibility of detail
Image of contrast resolution test tool can be used to create a contrast detail-curve Further the curve is toward y-axis, better contrast resolution and visibility of detail
37
Contrast detail curve
Smaller the object to be observed, the more contrast in the image you need in order to see it MRI has the best contrast resolution
38
Temporal resolution
Ability of an imaging system to show events that are happening close together in time as being separate events Applicable to real-time modalities such as fluoro, CT, MR angiography, MRI Affected by framte rate of acquisition and display rate
39
Frame rate
the number of frames/second or Hertz (Hz) The faster the frame rate, the better the temporal resolution, but the greater the patient dose.
40
Spatial resolution
The ability of an imaging system to create separate images of closely spaced objects. Also known as High Contrast Resolution. Is equivalent to recorded detail in DR
41
Spatial frequency
requires an image of a resolution pattern that creates a series of black and white lines Frequency of 5 lp/mm means that each black and white line is only 0.1 mm wide
42
Point spread function
Can also be used to measure spatial resolution A narrower peak on the graph indicates better spatial resolution
43
Line spread function
Creates a similar graph to Point Spread Function but requires a slit camera instead of a pinhole camera. The slit camera has an aperture that is 10 μm wide.
44
Edge spread function
Can also be used to measure spatial resolution Closer the graph is to the center line, the better the spatial resolution
45
Distortion
A misrepresentation of the true size, shape, or spatial relationship of the part in the radiographic image. 3 types of distortion: Size - msirepresentation of true size. SID, OID, SOD shape - Misrepresentation of true object shape. Elongation, foreshortening spatial - Misrepresentation of true spatial relationship between objects in image
46
Size distortion or magnification
Misrepresentation of true size of the object in the radiographic image Factors are: SID OID SOD
47
Effect of SID on magnification
As SID increases, the amount of magnification decreases due to less beam divergence Shorter SID will cause more magnification
48
Effect of OID on magnification
As OID increases, so does amount of magnification A decrease in OID will cause less magnification
49
Magnification calulations
Amount of Size Distortion * Image size/object size = SID/SOD Magnification Factor – tells how many times bigger image is than object * Use either half of the above equation Percent Magnification – tells what percent bigger is image than object * = (image size – object size)/object size x 100
50
Cieszynski's Law of Isometry
Can be used to determine foreshortening of objects that are not parallel to IR Cr angle should be 1/2 of the angle between the part and IR to minimize shape distortion
51
Spatial distortion
taking 3-dimensional object and capturing it in a 2-dimensional image Can be corrected by taking 2 separate images at 90 degrees from each other

Spring 2023 (81 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions