CRI Advanced Imaging Techniques 3

Question 1

In computed tomography, which artifact appears as streaks or bands between two highly attenuating objects such as metal fasteners?

Accepted Answer

Beam hardening artifact

Answer

Beam hardening causes streaks between dense objects because lower-energy photons are preferentially absorbed, shifting the beam spectrum and causing cupping or streaking.

Question 2

When selecting a scintillator for a flat panel detector used in high-energy industrial radiography (>1 MeV), the preferred scintillator material is typically:

Accepted Answer

Lutetium oxyorthosilicate (LSO)

Answer

Lutetium oxyorthosilicate and similar dense scintillators are preferred at MeV energies because their high atomic number and density provide adequate stopping power for high-energy photons.

Question 3

In laminography (also called computed laminography), the imaging geometry differs from standard CT in that:

Accepted Answer

The X-ray source and detector tilt around an oblique axis allowing flat extended objects to be imaged

Answer

Laminography uses a tilted rotation axis so the object can extend beyond the field of view, making it ideal for large flat components like circuit boards or fuselage panels.

Question 4

The dynamic range of a digital detector is most directly measured by:

Accepted Answer

The ratio of the maximum to minimum measurable signal (often expressed in bits)

Answer

Dynamic range is the ratio of the largest to smallest signal the detector can reliably measure, typically expressed as the number of bits in the analog-to-digital converter.

Question 5

In phase-contrast radiography, image contrast is generated primarily by:

Accepted Answer

Refraction and diffraction of X-rays at material interfaces

Answer

Phase-contrast imaging exploits the refraction of X-rays at interfaces between materials with different refractive indices, producing edge-enhancement effects even for low-attenuation materials.

(CRI) Certified Radiographic Interpreter Practice Test

(CRI) Certified Radiographic Interpreter Practice Test

CRI Advanced Imaging Techniques 3