GXMO Image Quality and Interpretation 2 — Questions and Answers
Question 1: Which artifact appears as a grid-like pattern overlaid on the radiographic image when the grid is not properly aligned with the X-ray beam?
- Moiré pattern (Correct answer)
- Quantum mottle
- Penumbra artifact
- Reticulation artifact
Correct answer: Moiré pattern
A moiré pattern results from misalignment between the grid lines and the scanning frequency, producing an interference pattern on the image.
Question 2: A radiograph shows areas of increased density at the periphery of the image with decreased density at the center. What is the most likely cause?
- Anode heel effect (Correct answer)
- Scatter radiation
- Double exposure
- Grid cutoff
Correct answer: Anode heel effect
The anode heel effect causes decreased intensity on the anode side and increased intensity on the cathode side, creating uneven density across the image.
Question 3: Which factor primarily determines the recorded detail (sharpness) in a radiographic image?
- Focal spot size (Correct answer)
- mAs setting
- Grid ratio
- Film processing temperature
Correct answer: Focal spot size
A smaller focal spot size reduces geometric unsharpness (penumbra), resulting in sharper recorded detail.
Question 4: When evaluating a chest radiograph, you notice the left hemidiaphragm appears elevated and the mediastinum is shifted to the left. What does this suggest?
- Left lung collapse (atelectasis) (Correct answer)
- Left-sided pleural effusion
- Right-sided tension pneumothorax
- Left-sided pneumothorax
Correct answer: Left lung collapse (atelectasis)
Atelectasis (collapse) causes the hemidiaphragm to elevate and shifts the mediastinum toward the affected side due to volume loss.
Question 5: What is the primary purpose of using a high kVp technique in chest radiography?
- To penetrate the mediastinum and show lung detail simultaneously (Correct answer)
- To reduce patient dose without affecting image quality
- To increase contrast between soft tissues
- To decrease the effect of scatter radiation
Correct answer: To penetrate the mediastinum and show lung detail simultaneously
High kVp (120+ kVp) provides sufficient penetration of the dense mediastinum while still showing lung parenchyma, balancing contrast across different tissue densities.
Question 6: Which term describes the ability of an imaging system to distinguish between two adjacent structures that have very similar subject contrast?
- Contrast resolution (Correct answer)
- Spatial resolution
- Dynamic range
- Modulation transfer function
Correct answer: Contrast resolution
Contrast resolution (low-contrast detectability) is the ability to differentiate between structures with similar densities, distinct from spatial resolution which refers to sharpness.
Question 7: A lateral lumbar spine radiograph shows the vertebral bodies but the spinous processes are not visible. What technique error is most likely responsible?
- Insufficient penetration (too low kVp) (Correct answer)
- Excessive mAs causing overexposure
- Grid lines superimposed on the image
- Patient rotation during exposure
Correct answer: Insufficient penetration (too low kVp)
Low kVp results in insufficient penetration through the dense posterior elements, making the spinous processes invisible on the lateral projection.
GXMO Image Quality and Interpretation 2
Which artifact appears as a grid-like pattern overlaid on the radiographic image when the grid is not properly aligned with the X-ray beam?