Digital Radiography

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You got 15 of 25 possible points.

Your score: 60%

Question 1

In digital radiography: Greater bit depth results in greater contrast displaying capability.

Greater bit depths means that more shades of grey can be encoded

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Greater bit depths means that more shades of grey can be encoded

Question 2

In digital radiography: Lossy compression of data results in non-identical data upon retrieval.

In order to reduce storage requirements, lossy compression results in loss of overall data

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In order to reduce storage requirements, lossy compression results in loss of overall data

Question 3

In digital radiography: During image processing, noise can be reduced using high pass spatial filtering.

High pass spatial filtering increases noise.

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High pass spatial filtering increases noise.

Question 4

In digital radiography: Low pass spatial filtering will enhance edges within an image.

Low pass spatial filtering results in smoothed edges

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Low pass spatial filtering results in smoothed edges

Question 5

In digital radiography: In the sampling of sine waves, for example in Fourier transformation, the wave must be sampled with a frequency of at least half the maximum frequency within the data to ensure aliasing will not occur.

Sampling frequency must be at least twice the maximum wave frequency being observed.

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Sampling frequency must be at least twice the maximum wave frequency being observed.

Question 6

In digital Radiography: The modulation transfer function reduces as spatial frequency increases.

Due to blurring of structures situated closer to one another

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Due to blurring of structures situated closer to one another

Question 7

In digital Radiography: The latitude for a computed radiography system is less than for a film-screen system.

It is much greater

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It is much greater

Question 8

In digital Radiography: In computed radiography there is a linear relationship between the log of the dose to the plate and the log of the response signal from the screen.

(For detailed explanation please refer to Farr's Physics for Medical Imaging, 2e)

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(For detailed explanation please refer to Farr's Physics for Medical Imaging, 2e)

Question 9

In digital Radiography: In similarity to film screening, the characteristic curve of the computed radiography system cannot be optimised for a particular projection.

It can be optimised by using histogram analysis and altering the gradient curve to which the intensity values are mapped

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It can be optimised by using histogram analysis and altering the gradient curve to which the intensity values are mapped

Question 10

In Digital Radiography: In computed radiography, the spatial resolution of the images produced is less than for conventional film-screen radiography.

Around 4 line pairs per mm in computed radiography compared to 8 line pairs per mm in conventional film-screen.

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Around 4 line pairs per mm in computed radiography compared to 8 line pairs per mm in conventional film-screen.

Question 11

In Digital Radiography: Spatial resolution in computed radiography images is in part limited by pixel size.

(For detailed explanation please refer to Farr's Physics for Medical Imaging, 2e)

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(For detailed explanation please refer to Farr's Physics for Medical Imaging, 2e)

Question 12

In Digital Radiography: In computed radiography, for a given pixel matrix size, reducing the plate size will reduce the spatial resolution.

The resolution will increase as a small physical area can by visualised over relatively more pixels

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The resolution will increase as a small physical area can by visualised over relatively more pixels

Question 13

In Digital Radiography: In computed radiography, increased phosphor thickness results in worsening of the resolution.

Due to scattering of laser light during the reading process

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Due to scattering of laser light during the reading process

Question 14

In Digital Radiography: There is better contrast in images formed from computed radiography than in film-screen radiography regardless of the gradient curve selected.

The correct gradient curve must be selected for the projection in order to optimise contrast

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The correct gradient curve must be selected for the projection in order to optimise contrast

Question 15

In Computed Radiography: It may be impossible to identify that an image has been overexposed simply by looking at the image.

The histogram analysis selects the useful data to map to the gradient curve and therefore may account for differences in exposure

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The histogram analysis selects the useful data to map to the gradient curve and therefore may account for differences in exposure

Question 16

In Digital Radiography: Thin film transistors store amplified signals as electric charge that are released when exposed to light.

The charge is released by applying a high potential.

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The charge is released by applying a high potential.

Question 17

In Digital Radiography: Each pixel has a single transistor in an amorphous silicon TFT array associated with it.

(For detailed explanation please refer to Farr's Physics for Medical Imaging, 2e)

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(For detailed explanation please refer to Farr's Physics for Medical Imaging, 2e)

Question 18

In Digital Radiography: In indirect conversion systems, an internally reflecting crystal with a low spread of light means that a thicker crystal can be used.

Because light divergence within the crystal is reduced

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Because light divergence within the crystal is reduced

Question 19

In Digital Radiography: Digital radiography systems generally have a better detective quantum efficiency than computed radiography systems meaning that a lower dose can be used without increase in quantum noise.

(For detailed explanation please refer to Farr's Physics for Medical Imaging, 2e)

Score: 1 of 1

Your answer	Choice	Correct?	Score	Feedback	Correct answer
	True		1
	False		0

(For detailed explanation please refer to Farr's Physics for Medical Imaging, 2e)

Question 20

In Digital Radiography: It is certain that a system with detective quantum efficiency (DQE) of 50% has a greater efficiency of photon detection than a system with a DQE of 40%.

It may do but you cannot be certain because the DQE also takes noise into account. The system with DQE 50% therefore may have a lower efficiency of photon detection but have less noise added to the signal.

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It may do but you cannot be certain because the DQE also takes noise into account. The system with DQE 50% therefore may have a lower efficiency of photon detection but have less noise added to the signal.

Question 21

In Digital Radiography: In high noise examinations, a lower bit-depth is acceptable .

(For detailed explanation please refer to Farr's Physics for Medical Imaging, 2e)

Score: 1 of 1

Your answer	Choice	Correct?	Score	Feedback	Correct answer
	True		1
	False		0

(For detailed explanation please refer to Farr's Physics for Medical Imaging, 2e)

Question 22

In Digital Radiography: Examinations with high dynamic range require a reduced bit depth.

A higher bit depth is necessary to adequately store the larger range of intensity values

Score: 1 of 1

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A higher bit depth is necessary to adequately store the larger range of intensity values

Question 23

In Computed Radiography: Computed radiography systems typically use barium fluorohalide doped with Europium as part of a photostimulable phosphor.

(For detailed explanation please refer to Farr's Physics for Medical Imaging, 2e)

Score: 0 of 1

Your answer	Choice	Correct?	Score	Feedback	Correct answer
	True		0
	False		0

(For detailed explanation please refer to Farr's Physics for Medical Imaging, 2e)

Question 24

In Digital Radiography: Typical spatial resolution of computed radiography systems is around 3-6 line pairs per mm.

(For detailed explanation please refer to Farr's Physics for Medical Imaging, 2e)

Score: 0 of 1

Your answer	Choice	Correct?	Score	Feedback	Correct answer
	True		0
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(For detailed explanation please refer to Farr's Physics for Medical Imaging, 2e)

Question 25

In Computed Radiography: The diameter of the laser beam used in the image reader will affect the spatial resolution.

(For detailed explanation please refer to Farr's Physics for Medical Imaging, 2e)

Score: 1 of 1

Your answer	Choice	Correct?	Score	Feedback	Correct answer
	True		1
	False		0

(For detailed explanation please refer to Farr's Physics for Medical Imaging, 2e)

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