Podcast
Questions and Answers
The two most important characteristics of an imaging modality are spatial resolution and ______ resolution.
The two most important characteristics of an imaging modality are spatial resolution and ______ resolution.
contrast
In digital imaging, you manipulate ______ to provide sufficient radiation for creating an image.
In digital imaging, you manipulate ______ to provide sufficient radiation for creating an image.
mAs
Spatial resolution is described by the quantity known as spatial ______.
Spatial resolution is described by the quantity known as spatial ______.
frequency
The smallest object that can be imaged is inversely proportional to ½ the spatial ______.
The smallest object that can be imaged is inversely proportional to ½ the spatial ______.
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In digital imaging, if the object is smaller than one ______, it cannot be visualized.
In digital imaging, if the object is smaller than one ______, it cannot be visualized.
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Film-screen imaging has the best spatial resolution, approximately ______ lp/mm.
Film-screen imaging has the best spatial resolution, approximately ______ lp/mm.
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CR is limited to approximately ______ to 5 lp/mm.
CR is limited to approximately ______ to 5 lp/mm.
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The highest spatial resolution is achieved by ______ with 15 lp/mm.
The highest spatial resolution is achieved by ______ with 15 lp/mm.
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Digital Radiography has a high MTF at low spatial frequencies and has an abrupt cutoff due to ______.
Digital Radiography has a high MTF at low spatial frequencies and has an abrupt cutoff due to ______.
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As spatial ______ increases, the objects that can be imaged become smaller.
As spatial ______ increases, the objects that can be imaged become smaller.
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Objects with high spatial frequency are generally ______ to image than those with low spatial frequency.
Objects with high spatial frequency are generally ______ to image than those with low spatial frequency.
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Fluoroscopy has a spatial resolution of ______ lp/mm.
Fluoroscopy has a spatial resolution of ______ lp/mm.
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The ability of a system to record available spatial frequencies is known as ______.
The ability of a system to record available spatial frequencies is known as ______.
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A system producing an image identical to the object would have an MTF of ______.
A system producing an image identical to the object would have an MTF of ______.
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The focal spot size was previously our limiting factor at ______ mm.
The focal spot size was previously our limiting factor at ______ mm.
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Digital radiography has improved contrast resolution but reduced ______.
Digital radiography has improved contrast resolution but reduced ______.
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CR and DR have better contrast resolution than __________ because of wider dynamic range.
CR and DR have better contrast resolution than __________ because of wider dynamic range.
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A 14-bit Dynamic Range DR system has __________ shades of gray.
A 14-bit Dynamic Range DR system has __________ shades of gray.
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The human eye can only discern about __________ shades of gray.
The human eye can only discern about __________ shades of gray.
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Optical Density (OD) on film can theoretically range from __________ to 4.
Optical Density (OD) on film can theoretically range from __________ to 4.
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The highest signal-to-noise ratio (SNR) with the least __________ is desired.
The highest signal-to-noise ratio (SNR) with the least __________ is desired.
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Dynamic range is the range of values that can be displayed by an imaging system in terms of __________.
Dynamic range is the range of values that can be displayed by an imaging system in terms of __________.
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Increasing __________ increases the signal-to-noise ratio (SNR).
Increasing __________ increases the signal-to-noise ratio (SNR).
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The practical application range of Optical Density is from __________ to 2.5 OD.
The practical application range of Optical Density is from __________ to 2.5 OD.
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Interventional Radiography typically uses ______ mA to reduce time.
Interventional Radiography typically uses ______ mA to reduce time.
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The lowest mA station(s) come with the option of a smaller ______ spot size.
The lowest mA station(s) come with the option of a smaller ______ spot size.
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To minimize motion, use a higher ______ and a shorter time.
To minimize motion, use a higher ______ and a shorter time.
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Patient dose is NOT affected by the ______ selected.
Patient dose is NOT affected by the ______ selected.
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Time can be expressed in fraction or ______.
Time can be expressed in fraction or ______.
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MA and Time are ______ proportional: as one increases the other decreases.
MA and Time are ______ proportional: as one increases the other decreases.
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Three-phase or high-frequency generators can typically provide an exposure time as short as ______ ms.
Three-phase or high-frequency generators can typically provide an exposure time as short as ______ ms.
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Single-phase generators cannot produce an exposure time less than ______ ms.
Single-phase generators cannot produce an exposure time less than ______ ms.
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New mAs = old mAs x new distance squared divided by old distance squared, so New mAs = 10 mAs x 72 inches squared divided by ______ squared.
New mAs = old mAs x new distance squared divided by old distance squared, so New mAs = 10 mAs x 72 inches squared divided by ______ squared.
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If the kVp is increased by 15%, the mAs must be cut in half to maintain ______.
If the kVp is increased by 15%, the mAs must be cut in half to maintain ______.
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Original factors include 15 mAs and ______ kVp.
Original factors include 15 mAs and ______ kVp.
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For a grid ratio of 12:1, the multiplier is ______.
For a grid ratio of 12:1, the multiplier is ______.
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To convert technique for a 10 x 12 IR, the multiplier is ______.
To convert technique for a 10 x 12 IR, the multiplier is ______.
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Using single phase equipment, Original Factors include 15 mAs, 70 kVp, and a ______ multiplier.
Using single phase equipment, Original Factors include 15 mAs, 70 kVp, and a ______ multiplier.
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To convert technique for a grid ratio from 6:1 to 12:1 ratio, the new mAs calculated is ______.
To convert technique for a grid ratio from 6:1 to 12:1 ratio, the new mAs calculated is ______.
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When converting mAs for three phase equipment, you multiply by ______.
When converting mAs for three phase equipment, you multiply by ______.
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Study Notes
Digital Imaging Fundamentals
- Spatial Resolution refers to the ability to image small objects clearly.
- In digital imaging, spatial resolution is limited by pixel size.
- The smallest object that can be visualized is limited to half the pixel size.
- The spatial frequency is measured in line pairs per millimeter (lp/mm).
- Higher spatial frequencies are harder to image.
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Contrast Resolution is the ability to distinguish between and visualize similar tissues.
- Digital imaging has a wider dynamic range compared to film-screen imaging.
- Dynamic range is the number of shades of gray a system can capture.
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Bit depth determines the number of shades of grey.
- A 14-bit system has 16,384 shades of gray.
- Window/Leveling allows viewing of specific tissues and densities.
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Signal-to-noise ratio (SNR) is the ratio of the image-forming x-rays to noise (scatter, etc.).
- Noise can limit contrast resolution.
- Higher SNR (less noise) is preferred.
- Patient Dose can be reduced by 20-50% with digital imaging but dose creep has occurred.
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mA Stations are typically available in increments of 100, with the lowest mA settings allowing for smaller focal spot selection.
- The selected mA station impacts the exposure time.
- Exposure time should generally be kept short to minimize patient motion, but it doesn't impact patient dose.
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mA and Time are inversely proportional.
- Decreasing time requires increasing mA to maintain the same mAs.
- Three-phase generators can produce exposure times as short as 1 ms.
- Portable equipment generally has fixed time options.
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Distance affects the technique. Use the Distance-Squared Law calculation.
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New mAs = old mAs x new distance2 / old distance2
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15% Rule helps adjust the technique based on kVp changes.
- Increasing kVp by 15% requires halving the mAs to maintain density.
- Decreasing kVp by 15% requires doubling the mAs to maintain density.
- Grid Ratio influences the technique; use the appropriate multiplier.
- Collimation Field Size affects the technique; use the appropriate multiplier.
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Generator Type affects the technique; use the appropriate multiplier.
- Three-phase generators require smaller mAs values compared to single-phase generators.
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Description
Explore the essential concepts of digital imaging, focusing on spatial and contrast resolution. Understand how pixel size, dynamic range, and bit depth affect image quality and visibility. This quiz will assess your knowledge of the technical aspects that influence digital imaging performance.
