Chapter 11 Digital Image Characteristics Flashcards
What is the smallest unit of digital information?
A bit (binary digit).
What is a group of 8 bits called?
A byte.
What does HVL (Half-Value Layer) measure in x-ray imaging?
Beam quality—the thickness of material needed to reduce x-ray intensity by 50%.
How does increasing kVp affect patient dose?
Higher kVp = Lower patient dose (due to increased penetration and reduced absorption).
What term describes the number of gray shades an imaging system can display?
Dynamic Range.
What is the principal source of noise in radiographic imaging?
Scatter radiation.
What does IR stand for in radiologic science?
Image Receptor.
What is the relationship between spatial frequency and spatial resolution?
Higher spatial frequency = Better spatial resolution.
What is the term for unintended optical density on an image?
Artifact.
What does MTF (Modulation Transfer Function) measure?
The ability of an imaging system to maintain image contrast at different spatial frequencies.
What is the effect of increasing distance on radiation intensity?
Intensity decreases with increasing distance (Inverse Square Law).
What is the difference between direct and indirect DR (Digital Radiography)?
Direct DR converts x-rays directly to an electronic signal, while indirect DR first converts them into light.
What is dose creep?
The gradual increase in radiation dose over time due to clinicians using higher exposures.
What does photoelectric absorption contribute to image quality?
Higher contrast (important for bone imaging).
What does scatter radiation do to image contrast?
Reduces contrast, making the image appear foggy.
What is the principal cause of abrupt x-ray tube failure?
Tungsten vaporization from the filament.
What is the line-focus principle?
Angling the anode to create a smaller effective focal spot, improving resolution.
What is the heel effect?
Uneven x-ray intensity due to self-absorption in the anode.
What does spatial resolution describe?
The ability to distinguish small structures on an image.
What is the formula for magnification factor?
MF = SID / SOD (Source-to-Image Distance / Source-to-Object Distance).
