1ST QUIZ Flashcards
exactness of representation of the patient’s anatomic structures on the radiograph within the useful density range
Radiographic Quality
radiograph that exactly reproduces the anatomic part.
-needed by radiologist to be able to make accurate diagnosis
HIGH QUALITY RADIOGRAPHS
contain information that is difficult for human eye to interpret, which can lead to repeated X-rays or missed diagnosis
POOR QUALITY RADIOGRAPHS
THREE MAJOR INTERRELATED CATEGORIES OF RADIOGRAPHIC QUALITY
Film factors
geometric factors
subject factors
THREE IMPORTANT CHARACTERISTICS OF RADIOGRAPHIC QUALITY
HIGH RESOLUTION
• LOW NOISE
• PROPER SPEED
is the ability to visually detect separate objects on a radiograph
resolution
2 TYPES OF RESOLUTION
spatial resolution
contrast resolution
refers to the bone versus soft tissue interface
spatial resolution
spatial resolution is measured in
LINE PAIRS PER MILLIMETER (1P/mm)
are terms commonly used when referring to spatial resolution
Details or visibility of detail
degree of sharpness of on a radiograph
Detail
allows the viewer to see detail because image and optical density are adequate.
visibility of detail
contrast differences between similar tissues such as liver and spleen.
contrast resolution
THREE COMPONENTS OF RADIOGRAPHIC NOISE
FILM GRAINiNESS
STRUCTURE MOTTLE
QUANTUM MOTTLE
distribution and size the silver-halide of crystals in the emulsion of the film.
Film graininess
similar to pilm graininess but refers to the phosphor of the radiographic screen rather than silver-halide crystals.
-is equally inherent and it contributes to little radiographer noise.
structure mottle
Principal cause of the radiographic noise. -refers to the randomness with which a low. number of x-ray photons interact with the. intensifying screens.
quantum mottle
ability of an x-ray film to respond to an X-ray exposure.
speed or sensitivity
they are affected by image receptor speed.
RESOLUTION and NOISE
Proper speed on the film-screen combination, limits patient dose but produces ____
high resolution, low noise radiograph.
FAST IMAGE RECEPTORS
• (400, 600, and above)
•HIGH noise and Low resolution
SLOW IMAGE RECEPTORS
(50,100, 200, and 300)
•Low noise and HIGH resolution
performed when a STEP-WEDGE image is flashed onto an x-ray film to simulate an exposure
sensitometry
performed when a STEP-WEDGE image is flashed onto an x-ray film to simulate an exposure- if not available, ______ maybe imaged.
ALUMINUM STEP-WEDGE
image shows the shades of gray, which demonstrate radiographic contrast or variations in optical density
step wedge
measures the light transmitted through the step-wedge increments
densitometer
used in processing ac in imaging departments -used by film manufacturing to determine the characteristics of x-ray film.
sensitometry and densitometry
•Testing sensitometry and Densitometry are similar, but the optical density (OD) numbers for film characteristics are plotted on _____
SEMI-LOGARITHMIC GRAPH.
when OD is plotted in semi-logarithmic graph paper, the result is a
characteristic curve
parts of characteristic curve
Toe and shoulder
It is relationship between optical density and radiationbexposure plotted on a graph.
Hand D CURVE (HUSTER AND DRIFFIELD CURVE)
slope of straight line portion
film contrast
determine on the log op Relative exposure scale. Fast speed film film to the right the lept and low speed
speed
range of exposure in the diagnostically useful range of the charactensfic curve.
latitude
•HIGH EXPOSURE LEVEL
Shoulder
Low exposure level
Toe
Intermediate exposure levels
-Region in which the optical density number from a properly exposed radiograph appear. When a characteristic curve is plotted from. densitometry numbers, CONTRAST, GRADIENT, and SPEED can be easily determined.
Straight line portion
what are the characteristics that can be seen when characteristic curve is plotted from. densitometry numbers,
CONTRAST, GRADIENT, and SPEED
are devices that measures optical density used to perform sensitometry and densito- metry.
Aluminum step wedge or Penetrometer & Densitometer
a device that has a light source focused
through a pinhole
DENSiTOMETER
-numerical value calculated between the level. of light incident on a processed step wedge image (lo) and level. mitted through that film. light trans-
it is a logarithmic function
optical density
what are the characteristics that curve shows
film contrast
speed
latitude
radiographic application
Fast image receptors
slow image receptors
