CRI Digital Radiography Systems 3

Question 1

What is the primary cause of 'quantum mottle' in digital radiographic images?

Accepted Answer

Insufficient number of X-ray photons reaching the detector

Answer

Quantum mottle (noise) results from statistical fluctuation in the number of X-ray photons absorbed by the detector; too few photons create a grainy, mottled appearance.

Question 2

In digital radiography, which process corrects for non-uniform detector pixel sensitivity across the imaging plate?

Accepted Answer

Gain calibration (flat-field correction)

Answer

Flat-field (gain) correction normalizes pixel-to-pixel sensitivity variations by dividing each pixel's value by a reference flat-field image acquired without a patient.

Question 3

Which DICOM standard attribute defines the manufacturer-specific exposure index for a digital radiographic image?

Accepted Answer

(0018,1405) Relative X-Ray Exposure

Answer

DICOM tag (0018,1405) Relative X-Ray Exposure stores the manufacturer-specific exposure index value that indicates detector dose level.

Question 4

What distinguishes a storage phosphor plate used in CR from a conventional intensifying screen?

Accepted Answer

The storage phosphor traps energy in metastable electron states that are released by laser stimulation during readout

Answer

CR storage phosphors trap excited electrons in F-centers (metastable states); stimulated luminescence is then triggered by a laser beam during the readout process.

Question 5

For industrial radiographic inspection per ASME or ASTM standards, which image quality indicator (IQI) type is most commonly used in the United States?

Accepted Answer

Plaque-type (hole-type) IQI per ASTM E1025

Answer

The plaque-type (hole-type) IQI per ASTM E1025 is the standard image quality indicator most widely used in US industrial radiographic practice.

(CRI) Certified Radiographic Interpreter Practice Test

(CRI) Certified Radiographic Interpreter Practice Test

CRI Digital Radiography Systems 3