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image production hw
Terms in this set (54)
Image Receptor exposure was formerly referred to as:
Visible differences in adjacent structures on a radiographic image describe:
The primary controlling factor(s) of contrast is (are):
kvp and bit depth
The 15% rule states that:
Receptor exposure may be halved by decreasing kVp by 15%
Choose all of the following statements that are accurate pertaining to the role of kVp in radiographic image production (choose 3):
-As kVp is increased, penetrating ability of the x-rays increases
-As kVp increases, receptor exposure increases
-As kVp is increased, more x-rays exit the patient to strike the image receptor
Given an original technique of 30 mAs and 80 kVp, which of the following would produce an image with double the receptor exposure?
30 mAs, 92 kVp
If SID is doubled, what may be said about receptor exposure?
Receptor exposure is reduced to one fourth
If SID is reduced by one half, what must be done to mAs to maintain a constant receptor exposure?
Reduce mAs to one fourth its original value
Choose all factors below that result in poor spatial resolution (choose 4):
-Large focal spot
Which of the following describes the relationship between receptor exposure and the use of grids?
Grids reduce receptor exposure unless mAs are increased to compensate
The use of filtration:
Has little effect on receptor exposure because x-rays removed from beam are not image-producing rays
The variation of x-ray intensity along the longitudinal axis of the x-ray beam describes:
Anode heel effect
The function of contrast is to:
Make detail visible
A radiographic image with few gray tones, primarily exhibiting black and white, would be described as having what type of contrast?
1. Long scale
2. Short scale
2 and 4
Lower spatial resolution may be caused by which of the following factors?
Wide pixel pitch
Choose all that describe the outcome of using high kVp (choose 3):
-Many gray tones
Choose all that describe the outcome of using low kVp (choose 3):
-Few gray tones
Differential absorption of the x-ray beam is a function of:
What effect does beam restriction have on contrast?
Increases contrast because of reduction in the number of Compton interactions that occur
The adjustment in technical factors required when using beam restriction is:
Increase mAs to compensate for the number of rays removed from the primary beam
The portion of contrast that is caused by variations in the anatomy or that is secondary to pathologic changes is called:
Spatial resolution is:
Geometric representation of the part being radiographed
Distortion is defined as:
Misrepresentation of an anatomic structure on the image
Elongation and foreshortening are examples of:
Distortion that occurs when the x-ray beam is angled against the long axis of a part is:
Distortion that occurs when the x-ray beam is angled along the long axis of a part is:
Grid ratio is defined as:
The ratio of the height of the lead strips over the distance between the lead strips
Grid frequency is defined as:
The amount of lead in the grid (expressed as the number of lead strips per inch)
A grid with lead strips and aluminum interspacers that are angled to coincide with the divergence of the x-ray beam is called a:
The range of SIDs that may be used with a focused grid is called:
The best scatter cleanup is achieved with the use of:
Grid cutoff may be described as:
Decreased density on a radiograph as a result of absorption of image-forming rays
Use of technique charts:
is helpful when manual techniques are used
When AEC is used, increasing the kVp:
decreases exposure time
Using a fixed mAS and variable kvp technique chart, each cm increase requires what adjustment in kVp?
increase 2 kvp
In radiography of a large abdomen, which is(are) effective way(s) to minimize scatter reaching the IR?
1. use close collimation
2. use of low mAs
3. use of a grid
In comparison with 60 kV, 80 kV will:
1. permit greater exposure latitude
2. produce more scatter
3. produce shorter scale contrast
Using a short SID with a large IR is likely to:
increase the anode heel effect
In computed radiography, each pixel corresponds to a shade of gray representing an area in the patient known as a(n):
Image noise can be decreased by
increasing x-ray dose.
Film screen has a _______________dynamic range, and digital imaging has a ______________dynamic range.
narrow : wide
In digital imaging, as the size of the image matrix increases:
1. FOV increases
2. pixel size decreases
3. spatial resolution increases
Resolution in CR increases as:
1. laser beam size decreases
2. monitor matrix size decreases
3. PSP crystal size decreases
The term voxel is associated with all of the following except:
measured in Z direction
field of view
field of view
For the same FOV, as the matrix size increases:
1. spatial resolution increases
2. image quality increases
3. pixel size decreases
In digital imaging, TFT/ DEL size is related to:
An interaction between x rays and matter would include all EXCEPT:
Small-angle scatter results in:
When the x-ray photon strikes an atom within the tissue being imaged and loses all of its energy to an inner shell electron of that atom, the photon is said to have been _____ and undergone the _____.
absorbed; photoelectric interaction
When the x-ray photon strikes an atom within the tissue being imaged and loses only part of its energy to an outer shell electron of that atom, the photon is said to have been _____ and undergone the _____.
scattered; Compton interaction
When the entering x-ray photon loses energy and changes its path of travel as a result of interacting with an atom, the interaction is known as the:
At higher kilovoltage, _____ photon interactions occur, resulting in _____ transmission.
Beam attenuation __________ with a higher-energy x-ray beam.
Brightness/density is a quality related to the _____________ of the radiographic image.
visibility of structures
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