ARRT Digital Imaging and Exposure Factors 2

Question 1

How does increasing the source-to-image receptor distance (SID) affect image magnification?

Accepted Answer

Decreases magnification

Answer

Increasing SID moves the X-ray source farther from the image receptor, reducing the divergence of the beam at the IR and decreasing magnification.

Question 2

What is the relationship between mAs and receptor exposure in digital radiography?

Accepted Answer

Direct relationship — doubling mAs doubles receptor exposure

Answer

mAs directly controls the quantity of X-ray photons produced; doubling mAs doubles the number of photons reaching the receptor and doubles exposure.

Question 3

Which factor primarily controls quantum noise (quantum mottle) in a digital radiographic image?

Accepted Answer

mAs (number of photons reaching the detector)

Answer

Quantum mottle is caused by insufficient photons reaching the detector; increasing mAs increases photon fluence and reduces this noise.

Question 4

What is the 15% rule in radiographic technique adjustment?

Accepted Answer

Increasing kVp by 15% has the same effect on exposure as doubling mAs

Answer

The 15% rule states that increasing kVp by 15% approximately doubles receptor exposure, equivalent to doubling the mAs.

Question 5

In digital imaging, what processing function allows the radiologist to adjust image brightness and contrast after acquisition?

Accepted Answer

Window level and window width adjustment

Answer

Window level controls the center of the displayed density range (brightness) and window width controls the range of densities displayed (contrast) in digital images.

ARRT - American Registry of Radiologic Technologists Practice Test

ARRT - American Registry of Radiologic Technologists Practice Test

ARRT Digital Imaging and Exposure Factors 2