Mammography, Portable Radiography & Mobile Radiography: Hard Expert Quiz

Question 1

In full-field digital mammography, which detector material is characteristically used in an indirect conversion system rather than a direct conversion system?

Accepted Answer

Cesium iodide coupled to amorphous silicon

Answer

Amorphous selenium

Answer

Cadmium zinc telluride

Answer

Lead oxide photoconductor

Question 2

Compared with a standard antiscatter grid exposure in mammography, which effect is most commonly expected when using slot-scanning breast imaging geometry?

Accepted Answer

Reduced scatter reaching the detector without a conventional moving grid

Answer

Increased heel effect across the chest-wall edge

Answer

Marked geometric magnification at all breast thicknesses

Answer

Higher focal spot blooming due to longer exposure time

Question 3

Why is rhodium often selected as a target or filter material in mammography for thicker or denser breasts compared with molybdenum-only spectra?

Accepted Answer

It produces a slightly higher effective photon energy that better penetrates dense tissue

Answer

It eliminates the need for breast compression during exposure

Answer

It creates a broader focal spot to reduce motion blur

Answer

It suppresses characteristic radiation to improve contrast

Question 4

In magnification mammography, which technical change is intentionally used to improve visualization of microcalcifications?

Accepted Answer

Use of an air gap with a small focal spot

Answer

Use of a larger focal spot with grid engagement

Answer

Use of lower SID with increased breast compression force only

Answer

Use of dual-energy acquisition with moving detector

Question 5

Which quality control parameter in mammography most directly evaluates the system's ability to reproduce tiny high-contrast objects and low-contrast masses simultaneously?

Accepted Answer

Accreditation phantom image scoring

Answer

Half-value layer measurement

Answer

Compression force reproducibility

Answer

Automatic exposure control backup time

Question 6

A mobile chest radiograph obtained in a supine intensive care patient shows diffuse hazy opacity and vascular indistinctness. Which factor most commonly causes pleural effusions to appear less conspicuous than on erect radiographs?

Accepted Answer

Posterior layering of fluid in the supine position

Answer

Greater source-to-image distance in mobile units

Answer

Use of antiscatter grids in all portable exams

Answer

Increased beam hardening from capacitor discharge generators

Question 7

Which statement best explains why AP portable chest radiographs can exaggerate apparent cardiac size compared with standard PA erect images?

Accepted Answer

The anterior position of the heart relative to the detector in AP views increases magnification

Answer

The shorter object-to-image distance of the heart causes minification

Answer

The lower tube potential increases edge enhancement around the mediastinum

Answer

The moving grid in bedside imaging widens mediastinal contours

Question 8

When performing a portable radiograph in an isolation room, which infection-control practice is generally preferred to reduce cross-contamination of the image receptor?

Accepted Answer

Use a double-bagging or approved protective cover technique for the detector

Answer

Place the detector directly under the patient linen to avoid motion

Answer

Remove the detector cover before leaving the patient room

Answer

Disinfect only the generator controls after the examination

Question 9

In portable radiography of the chest, what is the principal advantage of using a higher kVp technique with an appropriate detector exposure index target?

Accepted Answer

It improves long-scale contrast and penetration of mediastinal structures

Answer

It eliminates scatter, making grids unnecessary in all adults

Answer

It reduces the need for collimation because penetration is improved

Answer

It guarantees lower patient dose regardless of mAs selection

Question 10

Which mobile radiography scenario most strongly warrants consideration of a grid to preserve image contrast?

Accepted Answer

Adult chest radiograph with body thickness well over 10 cm

Answer

Pediatric forearm radiograph at low kVp

Answer

Finger radiograph using tabletop technique

Answer

Neonatal abdomen radiograph in an incubator

Question 11

What is the major operational difference between capacitor-discharge mobile X-ray units and high-frequency mobile units during exposure?

Accepted Answer

Capacitor-discharge units may show kVp drop during discharge, unlike more constant high-frequency output

Answer

Capacitor-discharge units cannot be used for chest imaging

Answer

High-frequency units require line power during every exposure

Answer

High-frequency units produce only direct current to the filament circuit

Question 12

In digital portable radiography, why is reliance on post-processing alone a poor substitute for tight collimation?

Accepted Answer

Wide collimation increases scatter and can degrade contrast before processing occurs

Answer

Post-processing cannot correct detector lag from repeated exposures

Answer

Cropping after exposure always changes the exposure index calculation to ideal values

Answer

Digital detectors automatically reject all off-focus radiation

Question 13

Tomosynthesis in breast imaging differs from conventional 2D mammography chiefly because it:

Accepted Answer

Acquires multiple low-dose projections over an angular range to reduce tissue overlap

Answer

Uses radionuclide uptake rather than X-ray attenuation

Answer

Produces a single high-magnification projection to replace compression

Answer

Eliminates the need for antiscatter correction in dense breasts

Question 14

Which artifact is especially associated with computed radiography plates used in portable imaging if cassettes are mishandled or dust-contaminated?

Accepted Answer

White line or speck artifacts from plate/screen contamination

Answer

Zipper artifact from RF shielding failure

Answer

Aliasing from stationary grid frequency mismatch

Answer

Moiré pattern from selenium detector lag

Question 15

For a critically ill patient requiring serial mobile chest radiographs, which practice best supports reproducible comparison over time?

Accepted Answer

Using consistent positioning, centering, SID, and exposure technique as closely as possible

Answer

Changing SID based on room layout at each visit

Answer

Alternating AP and PA projections to average magnification effects

Answer

Removing side markers from repeat studies to reduce clutter

Mammography, Portable Radiography & Mobile Radiography: Hard Expert Quiz

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