Fluoroscopy (Part 1)

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You got 23 of 30 possible points.

Your score: 77%

Question

In fluoroscopy with an image intensifier: Doubling the x-ray exposure to the input screen will double the light output on the output screen.

This can be described as a system gamma of 1.

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This can be described as a system gamma of 1.

Question

In fluoroscopy with an image intensifier: Electrons on the output screen are an exact but magnified replica of the electrons leaving the input screen. .

They are a minified replica

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They are a minified replica

Question

In fluoroscopy with an image intensifier: Flux gain is a result of the intensification of the electrons due to focusing.

Flux gain is due to acceleration of the electrons resulting in many more light photons being emitted at the output phosphor than were emitted at the input phosphor. The description in the question is of minification gain.

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Flux gain is due to acceleration of the electrons resulting in many more light photons being emitted at the output phosphor than were emitted at the input phosphor. The description in the question is of minification gain.

Question

In fluoroscopy with an image intensifier: Bringing the focus of the electrons closer to the input screen will result in improved spatial resolution.

Due to magnification. Do not confuse input and output screens.

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Due to magnification. Do not confuse input and output screens.

Question

In fluoroscopy with an image intensifier: Magnification results in increased brightness of the final image, assuming a fixed kV and mA.

It reduces the brightness

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It reduces the brightness

Question

In fluoroscopy with an image intensifier: Automatic brightness control routinely utilises the camera signal from the periphery of the image to adjust kV and mA to maintain an appropriate brightness level.

The centre of the image is usually used

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The centre of the image is usually used

Question

In fluoroscopy with an image intensifier: When utilising an anti-isowatt curve, automatic brightness control will increase both kV and mA proportionately, when image brightness reduces.

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

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

Question

In fluoroscopy with an image intensifier: When utilising a brightness control curve optimised for an iodine contrast study, as image brightness reduces automatic brightness control should increase only the kV until the max kV that can be sustained by the tube before increasing mA.

The description is a curve that is optimised for reduced dose at the expense of image quality. For iodine studies the kV should be maintained around 60 kV which is optimum for imaging iodine with a K-absorption edge of 33 keV.

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The description is a curve that is optimised for reduced dose at the expense of image quality. For iodine studies the kV should be maintained around 60 kV which is optimum for imaging iodine with a K-absorption edge of 33 keV.

Question

In fluoroscopy with an image intensifier: Increasing the gain in order to brighten a dark image will increase the noise.

As there is no increase in signal.

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As there is no increase in signal.

Question

In fluoroscopy with an image intensifier: Decreasing the gain for overly bright images will mean an unnecessarily high dose to the patient.

As the reduced brightness could have been achieved by reducing the number of photons instead of reducing the gain.

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As the reduced brightness could have been achieved by reducing the number of photons instead of reducing the gain.

Question

In fluoroscopy with an image intensifier: Assuming that brightness of the image is maintained by adjusting only kV and mA, magnification of the image results in an increased dose area product.

DAP remains the same as the increased dose is offset by a reduction in irradiated area.

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DAP remains the same as the increased dose is offset by a reduction in irradiated area.

Question

In fluoroscopy with an image intensifier: With standard fluoroscopy settings, entrance surface dose rates up to, but not exceeding 200 mGy/min are acceptable for any given field of view.

The upper limit is 100 mGy/min

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The upper limit is 100 mGy/min

Question

In fluoroscopy with an image intensifier: Using pulsed fluoroscopy, increasing the pulse rate increases the patient dose.

Effectively, more x-ray images are being taken therefore the dose is greater.

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Effectively, more x-ray images are being taken therefore the dose is greater.

Question

In fluoroscopy with an image intensifier: A typical digital spot image is equivalent to 2 minutes of continuous screening time at typical manufacturer settings.

It is closer to the equivalent dose for 2 seconds of screening.

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It is closer to the equivalent dose for 2 seconds of screening.

Question

In fluoroscopy with an image intensifier: Noise is increased if frame averaging is used.

Frame averaging is a smoothing algorithm and will reduce noise.

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Frame averaging is a smoothing algorithm and will reduce noise.

Question

In fluoroscopy : Veiling glare cause the centre of the image to be brighter than the peripheries.

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

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

Question

In fluoroscopy : Smaller image intensifiers suffer more from veiling glare.

It is more pronounced in larger image intensifiers

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It is more pronounced in larger image intensifiers

Question

In fluoroscopy : Pin cushion distortion results in magnification towards the edges of an image.

Due to the curved input screen

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Due to the curved input screen

Question

In fluoroscopy : Larger ambient magnetic fields will result in increased S-type distortion which is where straight structures appear curved.

Due to effects on the electrons as the travel within the image intensifier

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Due to effects on the electrons as the travel within the image intensifier

Question

In fluoroscopy : Spatial resolution is tested with a low kV to reduce the effects of scatter. .

With a high kV, scattered photons have a higher energy and are therefore more likely to have enough energy to leave the patient.

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With a high kV, scattered photons have a higher energy and are therefore more likely to have enough energy to leave the patient.

Question

In Digital subtraction angiography: The contrast image is subtracted from the mask to produce an image with only the contrast filled vessels.

The mask is subtracted from the contrast image

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The mask is subtracted from the contrast image

Question

In Digital subtraction angiography: If the kV and mA are kept constant, the subtraction of one image from another would decrease the signal to noise ratio.

As signal has been reduced

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As signal has been reduced

Question

In Digital subtraction angiography: In dual energy subtraction, subtraction of a low kV image from a high kV image could be used to minimise bone visualisation.

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

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

Question

In Digital subtraction angiography: Pixel shifting is used to describe a blur artefact observed when the patient moves.

Pixel shifting is the retrospective adjustment of the mask to improve the subtraction

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Pixel shifting is the retrospective adjustment of the mask to improve the subtraction

Question

In Digital subtraction angiography: An increase in mA is generally needed.

To counteract the reduction in signal to noise ratio.

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To counteract the reduction in signal to noise ratio.

Question

In fluoroscopy with flat plate detectors: Dynamic range is increased in comparison to fluoroscopy with an image intensifier.

Data with 14-bit depth can be stored

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Data with 14-bit depth can be stored

Question

In fluoroscopy with flat plate detectors: Spatial resolution is reduced in comparison to fluoroscopy with an image intensifier.

It is improved

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It is improved

Question

In fluoroscopy with flat plate detectors: Spatial resolution improves with magnification beyond the benefit from merely displaying a magnified image.

Pixel size remains the same

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Pixel size remains the same

Question

In fluoroscopy with flat plate detectors: There is less geometric distortion than with fluoroscopy with an image intensifier.

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

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

Question

In fluoroscopy with flat plate detectors: A CT scan can be performed and the image will suffer less from scatter than in conventional CT scanners.

A CT scan can be performed but it will suffer more from the effects of scatter.

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A CT scan can be performed but it will suffer more from the effects of scatter.

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