Chapter 17 (Viewing the Medical Image) Flashcards
Photometry and Image Display
What does ROI stand for in medical imaging?
Region of Interest – The specific area of anatomy being examined for diagnostic purposes.
Photometry and Image Display
What is photometry, and why is it important in radiology?
Photometry is the science of measuring the response of the human eye to visible light, crucial for optimizing image display on monitors.
Photometry and Image Display
What are the two types of human vision, and how do they differ?
Photopic (cone vision) for bright-light vision and Scotopic (rod vision) for dim-light vision.
Photometry and Image Display
What is the basic unit of photometry?
Lumen (lm) – measures the total intensity of light emitted by a source.
Photometry and Image Display
What does illuminance describe?
The intensity of light incident on a surface, measured in lux or foot-candles.
Photometry and Image Display
How is luminance intensity measured, and what does it represent?
It’s measured in candela per steradian (cd/sr) and represents the brightness of a source within a defined viewing area.
Photometry and Image Display
What is the Inverse Square Law in photometry?
Light intensity decreases in proportion to the square of the distance from the source (same principle as x-ray intensity).
Photometry and Image Display
What is the Cosine Law, and how does it affect monitor viewing?
Maximum luminance is observed when viewing straight-on; contrast and brightness decrease at angles.
Hard Copy vs. Soft Copy Display
What is the difference between a hard copy and a soft copy image?
Hard copy = printed film, soft copy = digital images on a display monitor.
Hard Copy vs. Soft Copy Display
Why are hard copies no longer widely used in radiology?
Digital imaging eliminates the need for film, allowing easier storage, retrieval, and postprocessing.
Types of Display Monitors
What is an LCD (Liquid Crystal Display)?
Most common digital display; uses liquid crystals and a backlight for image visualization.
Types of Display Monitors
How does LED (Light-Emitting Diode) display differ from LCD?
LED displays use electrical stimulation to emit light, are thinner, last longer, and have better brightness.
Types of Display Monitors
What is a CRT (Cathode Ray Tube) display, and why is it outdated?
Old TV-style monitors; replaced by LCD and LED due to bulkiness and inefficiency.
Types of Display Monitors
What is a Plasma Display Panel (PDP), and why is it no longer used?
Early flat-screen technology; inefficient, high energy use, and banned in some states due to environmental impact.
Image Processing in Digital Radiology
What is the goal of preprocessing in digital imaging?
To automatically correct artifacts and compensate for detector defects before display.
Image Processing in Digital Radiology
What is postprocessing, and why is it important?
Any image modifications after acquisition (contrast adjustment, edge enhancement) to improve diagnostic quality.
Light Emission Terminology
What is a phosphor, and how does it relate to x-ray imaging?
A material that emits visible light when exposed to x-rays, used in CR plates and intensifying screens.
Light Emission Terminology
What are the three types of luminescence?
- Fluorescence – Light emission stops when the stimulus is removed.
- Phosphorescence – Light continues after stimulus is removed.
- Electroluminescence – Light is emitted when electrically stimulated (e.g., LEDs).
Light Emission Terminology
How does ergonomics apply to radiologic technologists?
Adjusting workspaces, chairs, and monitor positions to reduce fatigue and injury risk.
Light Emission Terminology
How does monitor resolution affect spatial resolution in radiology?
Higher megapixel monitors improve spatial resolution, allowing better visualization of fine details in medical images.
