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WorksheetsImaging II: Beam Restriction Review
Total questions: 30
Worksheet time: 15mins
Based on the objectives related to scatter radiation and beam restriction: Which change in X‑ray beam characteristics occurs when kVp is increased?
Transmission decreases and photoelectric absorption increases.
Transmission increases while photoelectric absorption decreases.
Compton scatter decreases because photons have less energy.
All interactions increase equally regardless of energy.
Recall: What is the immediate effect on photon energy when kVp is increased during an exposure?
Photon energy decreases, leading to more absorption
Photon energy stays the same while quantity increases
Each photon has more energy, enabling greater transmission
Only low-energy photons are produced, reducing scatter
Skill/Concept: Based on high kVp conditions, which statement best explains why more scatter reaches the image receptor (IR)?
More interactions occur overall, so absorption dominates
High-energy photons interact primarily via Compton scatter, and the scattered photons have enough energy to escape the body and reach the IR
Photoelectric absorption increases with kVp, stopping scattered photons
Pairing high kVp with higher mAs boosts absorption pathways
Recall/Concept: When technologists increase kVp to maintain exposure, what typical adjustment and patient-dose outcome are expected?
Increase mAs; patient dose rises due to more absorption
Reduce mAs using the 15% rule; overall patient dose decreases because fewer photons are absorbed
Keep mAs unchanged; patient dose stays constant
Reduce SID; patient dose decreases by geometric divergence
Recall: Which statement best describes how increasing kVp affects patient dose when mAs is appropriately adjusted to maintain image brightness?
Patient dose generally decreases
Patient dose generally increases
Patient dose remains unchanged in all cases
Patient dose fluctuates unpredictably
Skill/Concept: In digital imaging, how does increasing kVp typically influence the appearance of contrast compared to film-screen imaging?
It leads to a longer scale of contrast, but digital post-processing can further adjust contrast
It causes a shorter scale of contrast that cannot be modified digitally
It produces pure black-and-white images with no gray tones in digital systems
It has no relationship to contrast in digital imaging
Recall: Dense tissues like bone and muscle have which characteristic that increases both Compton scatter and photoelectric absorption?
Lower electron density per cubic centimeter
Higher electron density with more electrons packed into the same space
Greater transparency to X‑rays
Fewer outer‑shell electrons available for interactions
Which statement best explains why increasing patient thickness typically raises the amount of Compton scatter in radiography?
Thicker patients present more tissue volume that interactions can occur in, increasing scatter production.
Thicker patients contain more high-atomic-number materials that favor photoelectric absorption over scatter.
Thicker patients reduce beam energy, causing fewer interactions and less scatter.
Thicker patients allow more primary photons to pass unaltered, decreasing scatter.
A technologist images two regions: a fatty area and a dense glandular area. Which outcome aligns with how tissue density influences interaction type?
The fatty area shows more photoelectric absorption because lower density favors absorption.
The glandular area shows more Compton scatter because higher density increases electron availability.
Both areas show identical proportions of scatter and absorption regardless of density.
The glandular area shows less scatter due to lower electron density.
A facility wants to reduce repeat mammograms due to motion blur and poor contrast. Which procedural adjustment directly applies the concept of compression to address both issues?
Use no compression to avoid patient discomfort and rely on higher mAs.
Apply firm, even compression to spread tissue, minimize motion, reduce scatter, and improve resolution.
Switch to a lower kVp without changing compression to eliminate motion blur.
Increase SID to reduce scatter while keeping the breast uncompressed.
Recall: In radiographic imaging, what is penumbra as described in the lesson about collimators?
The central area of maximum sharpness within the exposure field
The blurry, fuzzy edge that appears around the outside of an image
A pattern of quantum mottle produced by low mA
The high-contrast border created by grid lines
Refer to the described visual: a slide titled “Collimator and Off-Focus Radiation” shows two bullet lists comparing upper shutters (near the x-ray tube, reduce off-focus radiation, improve contrast, add slight inherent filtration) and bottom shutters (near the patient/output, shape the x-ray field to match the light field, control exposure field size/shape, reduce penumbra). Which statement best describes the primary function of the bottom shutters in a radiographic collimator?
They primarily reduce off-focus (leakage) radiation inside the housing.
They align the mirror to ensure the light field matches the X-ray field.
They shape and control the exposure field to match the light field, helping reduce penumbra.
They increase low-energy photon output to enhance detail.
Recall how the collimator’s light-localizing field works. Inside the collimator, a mirror reflects light so the technologist can see where the X-ray beam will hit before exposure. What routine quality control check ensures the light field and X-ray beam align correctly?
Verifying they match within ±2% of the source-to-image distance (SID).
Ensuring the light field area equals the detector’s full active area at any SID.
Confirming the mirror removes all low-energy photons from the beam.
Checking that the central ray is offset to compensate for penumbra.
Recall: Which component primarily reduces off-focus and leakage radiation before it reaches the patient by providing inherent filtration at the tube exit?
Upper shutters of the collimator
Bottom shutters closest to the patient
Automatic exposure control sensors
Image receptor grid
Which component creates the collimator light field used to outline the projected X-ray field on the patient or receptor?
A mirror reflecting a lamp inside the collimator
The X-ray tube filament glowing during exposure
An external laser pointer mounted on the housing
Fluorescent panels on the image receptor
Why must the collimator light field be accurately aligned with the actual X-ray field?
To ensure exposure time is shortened
To avoid motion blur caused by the lamp
To guarantee that the irradiated area matches the visualized area
To comply with battery requirements for the collimator lamp
Quality control checks on collimator alignment primarily assess which relationship?
Light field to X-ray field congruence
Tube warm-up procedure compliance
Grid ratio to focal distance matching
AEC chamber sensitivity
What does central ray marking on the collimator help the radiographer do?
Align the beam to anatomy and receptor center
Measure mAs during exposure
Determine grid cutoff direction
Verify focal spot size
Which statement best distinguishes inherent filtration from added filtration in the context of collimator housing?
Inherent filtration arises from tube/housing components; added filtration is intentionally placed materials
Inherent filtration is adjustable by the technologist; added filtration is fixed
Inherent filtration increases patient dose; added filtration decreases dose
Inherent filtration is part of the AEC circuit; added filtration is part of the grid
During QC, how can a radiographer verify light field–X-ray field congruence?
Expose a test phantom using the light field boundaries and compare to the irradiated area
Warm the tube for 5 minutes and check mA stability
Measure focal spot size using a pinhole camera
Inspect grid lines on a high-frequency image
What is the stated purpose of ancillary devices like lead masks and blockers for exams such as the lateral T‑spine?
Restrict the beam to a specific shape and help absorb scatter when scatter can be significant
Increase the image receptor sensitivity to low kVp exposures
Provide patient immobilization for long procedures
Automatically select the correct grid ratio
Which feature on the collimator guides accurate centering of the X-ray beam over the receptor?
Central ray crosshair or marking
AEC indicator light
Anode rotation speed display
Grid alignment arrow on the bucky
Which component contributes to filtering out low-energy photons without being an added filter?
Inherent filtration from the collimator housing and tube components
Lead blockers placed on the receptor
AEC sensor cover plates
Image receptor scintillator
What is the main safety reason to perform routine QC on collimator light field alignment?
To prevent unintended tissue irradiation outside the intended field
To maintain tube warm-up protocols
To ensure anode rotation is within limits
To reduce the need for grids
Which scenario most clearly indicates misalignment between the light field and X-ray field?
The exposed area on the image extends beyond the illuminated boundaries
The collimator lamp is dim but exposure is correct
The grid lines are visible at low kVp
The AEC terminates the exposure too early
Central ray marking is crucial because it:
Provides a reference point for aligning anatomy and receptor center
Defines the grid ratio used for the exam
Indicates the selected mA station
Marks the focal spot size on the control panel
Which statement about the relationship between collimation and scatter is most accurate?
Tighter collimation reduces scatter reaching the receptor
Wider collimation always improves contrast
Collimation does not affect scatter levels
Scatter depends only on grid ratio
Which device from the ancillary list is placed on the image receptor to block parts of the beam?
Lead blocker or lead shield
AEC chamber
Mirror assembly
Filter wheel
Before using a custom lead mask on a digital system, the radiographer should:
Verify with the vendor that the system supports its use
Increase kVp by 10% to compensate
Disable AEC in all cases
Switch to a lower grid ratio
For exams with high scatter such as lateral thoracic spine, ancillary devices are recommended to:
Restrict the beam shape and absorb scatter
Increase SID to reduce magnification
Open collimation to include all anatomy
Replace the grid entirely
