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WorksheetsImaging I: Scatter Radiation Review
Total questions: 53
Worksheet time: 27mins
Which interaction is the primary source of scatter radiation in diagnostic imaging?
Photoelectric absorption in soft tissue
Pair production in dense bone
Compton interaction with outer-shell electrons
Coherent scattering at low photon energy
Increasing kVp typically has what effect on scatter production?
Lower kVp greatly reduces scatter
Higher kVp generally increases scatter
kVp has no impact on scatter
Higher kVp eliminates Compton events
Why does thicker or denser tissue produce more scatter?
Electrons are tightly bound preventing scatter
More atoms provide more interaction opportunities
Fewer atoms create fewer interactions
Shorter path length limits collisions
How does scatter radiation affect image contrast on the receptor?
Has no noticeable effect on contrast
Reduces contrast making images look gray
Creates high-contrast black-and-white appearance
Improves edge visibility and sharpness
What consequence can scatter have on patient dose during imaging?
Eliminates dose by absorbing all photons
Increases dose if technique is raised to compensate
Decreases dose due to fewer photons
Keeps dose unchanged regardless of technique
At higher photon energies, why do Compton interactions become more likely than photoelectric absorption?
Tissue density drops at high energy
Receptor sensitivity masks photoelectric
Outer-shell electrons bind more tightly
Photon energy favors Compton over photoelectric
Which statement best describes how longer photon path lengths influence scatter?
They convert scatter into primary radiation
They have no effect on scatter production
They increase scatter by enabling more interactions
They reduce scatter by shortening travel
Which method primarily narrows the x‑ray beam to reduce scatter by decreasing field size?
Air‑gap technique increasing distance
Aperture diaphragms with fixed opening
Lead shielding around sensitive tissues
Collimation using adjustable shutters
Cones or cylinders are used mainly to accomplish which outcome?
Prevent scatter from reaching sensitive tissues
Remove low‑energy photons from the beam
Reduce off‑focus radiation and scatter
Limit beam size to reduce total scatter
What best describes the function of an aperture diaphragm?
Increased distance between patient and IR
Adjustable shutters narrowing field size
Lead shield blocking scatter to organs
Metal plate with fixed opening limiting beam
Filtration primarily reduces which component to lower dose and scatter?
Backscatter from the image receptor
Off‑focus radiation outside light field
Low‑energy photons contributing to dose
High‑energy photons increasing penetration
Shielding helps reduce patient risk by doing what?
Restricting the beam to area of interest
Preventing scatter from reaching tissues
Allowing scatter to diverge from IR
Hardening the beam to reduce scatter
The air‑gap technique improves image contrast mainly because it:
Blocks scatter using lead shielding
Increases distance so scatter misses IR
Removes low‑energy photons via filtration
Narrows the beam with adjustable shutters
Decreasing field size during collimation generally leads to:
Less tissue exposed and less scatter
More tissue exposed and more scatter
Higher kVp and increased Compton
Harder beam with more penetration
Which pair correctly matches method to primary effect on scatter?
Cones—remove low‑energy photons from the beam
Air‑gap—increases distance so scatter diverges
Shielding—narrows field to the anatomy of interest
Filtration—blocks scatter at the patient surface
Which statement best defines collimation in radiography?
Filtering low-energy photons from the beam
Increasing kVp to penetrate thicker anatomy
Restricting the x-ray beam using shutters
Expanding field size for full body imaging
What is the effect of decreasing field size on image contrast?
Contrast fluctuates with patient position
Contrast remains unchanged overall
Contrast increases due to less scatter
Contrast decreases due to more scatter
How does increasing field size influence patient dose?
Dose decreases because fewer interactions
Dose decreases when filtration is added
Dose increases because more tissue exposed
Dose stays the same with proper shielding
Why does tighter collimation often require increasing mAs?
It reduces beam intensity reaching the IR
It raises kVp and reduces attenuation
It widens field size to include more tissue
It shortens exposure time automatically
A technologist halves the field size for a knee exam. What change in mAs is typically needed to maintain receptor exposure?
Double mAs and kVp together
Increase mAs by 30–50 percent
Keep mAs exactly the same
Decrease mAs by 30–50 percent
Which sequence correctly describes the chain when field size is increased?
Less tissue exposed → less scatter → higher contrast
More tissue exposed → more scatter → lower contrast
Less tissue exposed → more scatter → higher contrast
More tissue exposed → less scatter → higher contrast
Which device primarily limits beam size to reduce off-focus radiation?
Lead shielding placed on patient
Filtration using aluminum inserts
Cones or cylinders positioned at tube
Aperture diaphragm with fixed opening
What is the primary function of a radiographic grid?
Amplify primary beam intensity reaching the IR
Focus the x-ray beam to a smaller field size
Convert scattered photons into useful signal
Absorb scatter before it reaches the image receptor
Which materials typically compose a radiographic grid?
Aluminum plates with steel spacers
Lead strips with radiolucent interspaces
Lead and radiopaque copper spacers
Tungsten plates with carbon fiber gaps
How do grids remove scatter from the x-ray beam?
By bending scattered photons back to the detector
By only allowing straight-line photons to pass
By amplifying low-energy scattered radiation
By redirecting angled photons toward the IR
A grid with a ratio of 12:1 compared to 5:1 will most likely:
Provide less scatter cleanup with lower mAs needed
Provide better scatter cleanup but require more technique
Provide better cleanup with reduced patient dose
Provide equal scatter cleanup with identical exposure
What is the effect of higher grid frequency on image quality?
More strips per inch yields markedly higher cleanup
Fewer strips per inch yields more scatter removal
More strips per inch yields a smoother image
Higher frequency always decreases image contrast
When should a grid be used during radiographic imaging?
When magnification is desired over contrast
When part thickness is under 5 cm
When kVp is below 50 and scatter is minimal
When body part exceeds 10 cm or kVp is 60–70
Using a grid affects exposure settings by typically requiring:
Unchanged mAs because only scatter is removed
Higher mAs because grids absorb some primary beam
Lower mAs due to increased beam intensity
Lower kVp to compensate for grid frequency
What is the trade-off when using a grid regarding patient dose and image contrast?
Lower dose with slightly reduced contrast
Higher dose with improved image contrast
Lower dose with markedly improved contrast
Equal dose with unchanged image contrast
Which statement best describes linear grids?
Lead strips run randomly to absorb more scatter
Lead strips form a focused pattern disallowing angling
Lead strips run in one direction allowing CR angling
Lead strips run in two perpendicular directions
Which feature best defines a linear grid in radiography?
Lead strips run in one direction
Lead strips intersect at right angles
Lead strips angled to beam divergence
Lead strips straight with no angling
What is a key limitation of cross-hatched grids?
Require higher kVp settings
Do not allow tube angling
Cannot be used at long SIDs
Produce excessive blur of grid lines
Focused grids are designed with lead strips that:
Are stationary during exposure
Intersect to increase scatter cleanup
Are angled to match beam divergence
Run parallel to the IR edges
Non-focused (parallel) grids are most likely to cause grid cutoff when:
Using a moving bucky during exposure
Angling the tube within the SID range
Using high grid ratios and low kVp
Using short SIDs or large field sizes
Which statement best distinguishes stationary from moving (bucky) grids?
Moving grids cannot be used in tables
Moving grids show visible grid lines
Stationary grids blur grid lines
Stationary grids do not move during exposure
In a moving/bucky grid, the primary purpose of movement during exposure is to:
Allow tube angling
Match beam divergence
Increase scatter production
Blur visible grid lines
Which orientation describes a long-dimension grid relative to the image receptor?
Strips run across the short axis
Strips run along the long axis
Strips intersect at ninety degrees
Strips angled to match divergence
Short-dimension grids are particularly helpful for which scenario?
Cross-table lateral projections
Mobile AP abdomen studies
High kVp chest imaging
Long SID extremity imaging
Which visual sign best indicates an off-level grid error during an exposure?
Severe cutoff on both edges only
Uniform grid cutoff across the image
Cutoff more pronounced on one side
Loss of exposure at image edges
A radiograph shows more cutoff on the left side while the right side appears relatively normal. What grid error is most likely?
Off-center alignment to the grid
Off-level tilt of the grid
Moiré interference pattern
Upside-down focused grid
Using a focused grid at the wrong SID most commonly produces which appearance?
Loss of exposure on edges, center okay
Uniform cutoff across the image
Severe cutoff on both edges, center exposed
Wavy zebra-like banding pattern
Placing a focused grid backwards during imaging typically results in what outcome?
Loss of exposure limited to edges
Uniform grid cutoff across the image
Subtle one-sided cutoff gradient
Severe cutoff on both edges, center exposed
A wavy, zebra-like pattern appears when using a stationary grid with digital image receptors. What is the underlying issue?
Grid or tube is tilted relative
Wrong SID for a focused grid
Tube not centered to the grid
Grid frequency is too low for sampling
Which scenario best distinguishes off-level from off-center grid errors?
Off-level shows edge loss; off-center shows uniform cutoff
Off-level shows wavy bands; off-center shows edge loss
Off-level shows uniform cutoff; off-center shows one-sided cutoff
Off-level shows severe edge cutoff; off-center shows center-only exposure
Which scenario most clearly indicates using a grid to improve image contrast?
Portable chest at sixty kVp with small field
Part thickness greater than ten centimeters
Extremity imaging at low kVp settings
Pediatric abdomen using minimal exposure
A technologist observes uniform grid cutoff across the entire image. Which grid error best matches this presentation?
Off-center with tube not aligned
Off-level due to tilted grid or tube
Off-focus with wrong SID used
Upside-down focused grid placed
What is the most appropriate action to avoid off-center grid cutoff during imaging?
Use compression to reduce thickness
Open the collimation widely
Increase kVp to penetrate the grid
Center the tube to the grid lines
Which method reduces scatter when a grid is not available and maintains image contrast?
Place the grid upside-down intentionally
Raise kVp beyond acceptable range
Remove collimation to increase field
Use air gap technique to separate patient
A focused grid is used at the wrong SID. What image effect should be expected?
Loss of exposure at the image edges
Uniform cutoff across the entire field
Wavy zebra-like interference pattern
Pronounced cutoff on only one side
How does increasing field size typically affect patient dose and image contrast?
Increases contrast and decreases dose
Decreases scatter and decreases dose
Increases scatter and increases dose
Decreases scatter and increases contrast
After tightening collimation for a study, what adjustment to mAs is generally recommended?
Double mAs and reduce kVp substantially
Increase mAs by roughly thirty to fifty percent
Hold mAs constant regardless of field size
Decrease mAs to compensate for added scatter
Which condition is most associated with the moiré pattern on a digital image?
Stationary grid with low grid frequency
High kVp with focused grid at correct SID
Angling the tube across the grid lines
Small field size producing high contrast
