Radiography Exam Image Production & Processing 2 — Questions and Answers
Question 1: Which term describes the process of adjusting image brightness and contrast after acquisition in digital radiography?
- Preprocessing
- Postprocessing (image manipulation) (Correct answer)
- Exposure latitude correction
- Histogram analysis
Correct answer: Postprocessing (image manipulation)
Postprocessing allows digital manipulation of window width and window level after the image is acquired, adjusting contrast and brightness.
Question 2: What does window width (WW) control in digital image display?
- Image brightness (overall lightness/darkness)
- Image contrast (the range of gray shades displayed) (Correct answer)
- Image sharpness
- Image noise level
Correct answer: Image contrast (the range of gray shades displayed)
Window width determines the range of Hounsfield units (or signal values) mapped to the gray scale, controlling the number of gray shades and thus image contrast.
Question 3: In computed radiography, what material is used in the imaging plate to store the latent image?
- Silver halide crystals
- Photostimulable phosphor (PSP) (Correct answer)
- Cesium iodide
- Amorphous selenium
Correct answer: Photostimulable phosphor (PSP)
CR imaging plates use photostimulable phosphor (typically europium-doped barium fluorohalide) to trap energy from x-rays as a latent image.
Question 4: What is the effect of increasing SID on radiographic magnification?
- Magnification increases
- Magnification decreases (Correct answer)
- Magnification is unaffected by SID
- Magnification doubles with every 10 cm increase in SID
Correct answer: Magnification decreases
Increasing SID reduces magnification because the object is a smaller proportion of the total source-to-image distance.
Question 5: Which grid ratio produces the greatest cleanup of scatter radiation?
- 4:1
- 8:1
- 12:1
- 16:1 (Correct answer)
Correct answer: 16:1
A 16:1 grid ratio provides the most efficient scatter cleanup because the tall, closely spaced grid strips preferentially absorb angled scatter photons.
Question 6: What is the primary purpose of the anti-scatter grid in radiography?
- To increase patient dose
- To improve image contrast by absorbing scatter radiation before it reaches the detector (Correct answer)
- To collimate the primary beam
- To filter low-energy photons from the beam
Correct answer: To improve image contrast by absorbing scatter radiation before it reaches the detector
Anti-scatter grids absorb scattered photons that would otherwise reach the detector and reduce image contrast.
Radiography Exam Image Production & Processing 2
Which term describes the process of adjusting image brightness and contrast after acquisition in digital radiography?