Ch. 28 Recorded Detail (Exp I & II) Flashcards
Recorded detail is…
- The degree of geometric sharpness
- Definition
- The accuracy of the structural lines actually recorded in the radiographic image
The unit of resolution in film/screen imaging is…
Line pairs per mm
Poor resolution is caused by unacceptable levels of…
Penumbra
Which can negatively impact recorded detail?
a. Using small focal spot
b. Good film-screen contact
c. Involuntary motion
d. Minimal OID
c. Involuntary motion
Factors affecting recorded detail include…
Focal spot size
Resolution is improved when…
SID increases and OID decreases
Spatial resolution in digital imaging is determined by the…
- Bit depth
- Matrix size
- Pixel size
Which radiograph exhibits the bet detail?
a. PA chest for evaluation of heart at 40”
b. PA chest for evaluation of heart at 72”
c. AP chest for evaluation of heart at 40”
d. AP chest for evaluation of heart at 72”
b. PA chest for evaluation of heart at 72”
As focal spot size decreases…
- Umbra is improved
- Penumbra decreases
- Resolution increases
Penumbra decreases as…
- Focal spot decreases
- OID decreases
- SID increases
Slow film-screen combinations…
Increase resolution
Resolution with intensifying screens will increase as ____ increases.
Phosphor concentration
The best method for controlling motion when the patient is unable to cooperate is to…
Maintain mAs, while decreasing time.
As a last resort, which human immobilizer is used to hold a patient in position?
The male relative
The ____ represents a depth to the information in the digital image.
z axis
Which measures the accuracy of an image compared to the original object on a scale of 0 to 1?
Modulation Transfer Function (MTF)
All of the following increase visibility of detail EXCEPT:
a. 15% rule
b. filtration
c. Radiographic grids
d. SID
d. SID
When evaluating the degree of resolution on an actual radiographic image, an effective tissue to analyze is…
Bony trabecular pattern
A pixel bit depth of 2^16 will demonstrate ____ shades of gray.
65,536
As the spatial frequency of objects increases,
MTF decreases
For general radiography, an MTF value of 1 is…
Theoretically impossible
Imaging noise is different from quantum noise in that imaging noise…
Is inherent in the imaging system
In general radiography, quantum noise is…
A function of mAs and kVp.
The Nyquist frequency is…
Sampling a minimum of twice per cycle
In digital imaging systems, increasing sampling frequency of the data…
Increases image fidelity
When the sampling frequency is less than the Nyquist value,
The Moire effect can occur
The overall general shape of a human anatomical structure is…
Round or oval
A digital detector with a high fill factor…
Will produce high resolution
You have completed a chest radiograph on a 2 month old infant using a restraining device at 72” SID. Because of the design of the device, your OID is suboptimum. The image reveals good resolution of the bony anatomy, but the pulmonary vasculature is blurred. The EI value is 2040. In an effort to improve the quality of the repeat image, the competent radiographer would…
Raise mA and decrease the exposure time.
