Lesson 3 Part 2 Flashcards
• Description: Films designed for specific imaging tasks not covered by standard film types.
• Characteristics: Tailored properties to meet unique imaging requirements.
• Applications: Angiography, subtraction radiography, and other specialized procedures.
Specialty/special application film
Humidity level?
30-60%
Store films in a cool, dry place with temperatures below ?
20 degree celsius (68 F)
Using expired film can lead to ?
reduced speed, decreased contrast, and increased fog.
the outermost component of a radiographic intensifying screen, positioned closest to the radiographic film. Its primary function is to shield the underlying phosphor layer from physical damage and contamination. This layer is typically composed of a thin, transparent cellulose compound
Protective layer
Thickness of protective layer of intensifying screen?
10 to 25 micrometers (µm).
is the active component of a radiographic intensifying screen, responsible for converting x-ray energy into visible light, thereby enhancing the exposure of the radiographic film. This process significantly reduces the required x-ray dose, minimizing patient exposure.
Phosphor layer
Favorable Properties of Phosphors
- High Atomic Number
- High Detective Quantum Efficiency (DQE)
- High Conversion Efficiency (CE)
- Spectral Matching
This property indicates the percentage of x-rays absorbed by the screen, with higher DQE values leading to better image quality.
High Detective Quantum Efficiency (DQE)
refers to the rate at which absorbed x-ray energy is transformed into visible light.
High Conversion Efficiency (CE)
This is the immediate emission of light during x-ray exposure
Fluorescence
This refers to the delayed emission of light after the x-ray exposure has ended.
• Phosphorescence (Screen Lag or Afterglow)
is a crucial component of a radiographic intensifying screen, positioned between the phosphor layer and the base. Its primary function is to enhance the efficiency of the screen by redirecting light emitted by the phosphor crystals toward the film.
Reflective layer
serves as the foundational support for the active phosphor layer. Positioned farthest from the film, it ensures the structural integrity and optimal performance of the screen
Base layer
PRIMARY CHARACTERISTICS OF RADIOGRAPHIC INTENSIFYING SCREENS
screen speed, image noise, spatial resolution, contrast, and latitude.
refers to the efficiency with which an intensifying screen converts x-ray energy into visible light, thereby exposing the radiographic film.
Screen Speed
refers to the random fluctuation of optical density in a radiographic image, which can obscure fine details and reduce diagnostic quality.
Image noise
is the ability of an imaging system to distinguish small, closely spaced objects as separate entities. In intensifying screens, spatial resolution is affected by factors such as phosphor crystal size, screen thickness, and the presence of a reflective layer.
Spatial resolution
refers to the difference in optical density between adjacent areas on a film, allowing differentiation of anatomical structures.
Contrast
refers to the range of exposure over which a radiographic film can produce acceptable image densities
Latitude
play a crucial role in radiographic imaging by providing a portable, lightproof enclosure for film while optimizing the use of intensifying screens and attenuating residual X-ray beams. Their design helps enhance image quality and minimize unnecessary radiation exposure.
Cassettes and holders
for specific anatomical imaging
Curved cassette
for facial and dental radiography
Panoramic casette
has been instrumental in advancing the understanding of photographic processes, particularly in medical and industrial radiography, where precise image capture is crucial. By elucidating the microscopic events leading from exposure to image development, this theory has laid the groundwork for innovations in film technology and processing techniques.
The Gurney-Mott theory
Materials commonly used for the reflective layer
magnesium oxide and titanium dioxide,
are essential components in medical imaging, designed to enhance the efficiency of X-ray imaging systems. They function by converting X-ray photons into visible light, which then exposes the radiographic film, thereby reducing the required radiation dose to the patient.
Radiographic intensifying screens
The typical thickness of reflective layer
25 micrometers
The Gurney-Mott theory, proposed by
Ronald Wilfred Gurney and Nevill Francis Mott in 1938
