Radiography Exam Radiology Tech 4 — Questions and Answers
Question 1: What is the primary advantage of digital radiography (DR) over computed radiography (CR)?
- Lower patient dose in all circumstances
- Faster image acquisition with no cassette handling (Correct answer)
- Better spatial resolution in all cases
- Lower equipment cost
Correct answer: Faster image acquisition with no cassette handling
Direct digital radiography (DR) captures images instantly via a flat-panel detector, eliminating the cassette handling and plate-scanning steps required in CR.
Question 2: What is the inverse square law as applied to X-ray intensity?
- Intensity increases proportionally with distance
- Intensity is inversely proportional to the square of the distance from the source (Correct answer)
- Intensity is proportional to the square root of the distance
- Intensity doubles when distance is halved
Correct answer: Intensity is inversely proportional to the square of the distance from the source
The inverse square law states that radiation intensity decreases as the inverse square of the distance from the source (I1/I2 = D2²/D1²).
Question 3: Which structure in the X-ray tube acts as the source of electrons?
- Focusing cup
- Anode
- Filament (cathode) (Correct answer)
- Rotor
Correct answer: Filament (cathode)
The filament, located within the cathode assembly, undergoes thermionic emission when heated, releasing electrons that are accelerated toward the anode.
Question 4: What does OID stand for and how does it affect image magnification?
- Object-Image Distance; larger OID decreases magnification
- Object-Image Distance; larger OID increases magnification (Correct answer)
- Output Intensity Detector; affects density
- Optimal Irradiation Dose; affects patient exposure
Correct answer: Object-Image Distance; larger OID increases magnification
OID (Object-Image Distance) is the distance between the patient part and the image receptor; increasing OID increases geometric magnification and blur.
Question 5: Which type of ionizing radiation has the greatest penetrating power?
- Alpha particles
- Beta particles
- Gamma rays (Correct answer)
- Neutrons
Correct answer: Gamma rays
Gamma rays (and X-rays), as high-energy electromagnetic radiation, have the greatest penetrating power among common ionizing radiations.
Question 6: What is the purpose of collimation in radiography?
- Increase the number of X-rays produced
- Restrict the X-ray beam to the area of interest (Correct answer)
- Filter out high-energy photons
- Increase patient dose
Correct answer: Restrict the X-ray beam to the area of interest
Collimators use lead shutters to restrict the X-ray beam to the anatomical area of interest, reducing patient dose and scattered radiation.
Question 7: Which artifact on a digital radiograph is caused by insufficient X-ray exposure to the detector?
- Quantum mottle (noise) (Correct answer)
- Ghosting
- Grid cutoff
- Moiré pattern
Correct answer: Quantum mottle (noise)
Quantum mottle (image noise) results from too few X-ray photons reaching the detector, producing a grainy, speckled appearance.
Radiography Exam Radiology Tech 4
What is the primary advantage of digital radiography (DR) over computed radiography (CR)?