Radiographic Image Quality Flashcards
the exactness of representation of the patient’s anatomy on a radiographic image
RADIOGRAPHIC IMAGE QUALITY
To produce high-quality images, radiographers apply knowledge of the three major interrelated categories of radiographic quality:
- Film Factors
- Geometric Factors
- Subject Factors
Is the amount of luminance (light emission) of a display monitor
BRIGHTNESS
Is the density difference between neighboring regions on a plain radiograph
CONTRAST
Is a measure of the degree of film darkening or the amount of overall blackness of the film
DENSITY
- Observed in radiographs where density differences are notably distinguished (black to white).
- High contrast image shows fewer gray levels and greater differences among them
High Radiographic Contrast (Short Scale)
- Seen on radiographic images where adjacent regions have a low-density difference (black to grey).
- Low-contrast image showing many gray levels and few differences among them
Low Radiographic Contrast (Long Scale)
foreign object =
Low contrast
- The difference in x-ray photon transmission between different areas of the body
- The primary controlling factor is M
- Describes the different amounts of exit radiation through different parts of the body
- Depends on differential absorption of the x-ray beam
SUBJECT CONTRAST
EVERY THING IS BLACK/ WHITE ON FILM WITH FEWER SHADES OF GRAY IN BETWEEN
SHORT SCALE
SHADES OF GRAY IN BETWEEN THE LIGHTEST AND DARKEST PORTIONS OF IMAGE
LONG SCALE
Is used to describe the ability of an imaging receptor to distinguish between objects having similar subject contrast
CONTRAST RESOLUTION
- BLANK in radiology refers to the ability of an imaging system to differentiate between two nearby objects.
- The absence of BLANK in an image may be referred to as blur.
- It is expressed in line pairs per mm (Ip mm)
- In digital imaging, it depends on the size of the pixel used
- A large pixel size will be unable to resolve two nearby structures as compared to a small pixel size
SPATIAL RESOLUTION
- The most common way of measuring spatial resolution is called BLANK defined as the number of details that can be fit into a given space.
- Spatial resolution can be recorded by taking the BLANK from a line-pair resolution template
spatial frequency
- Results from the radiographic misrepresentation of either the size (magnification) or the shape of the anatomic part.
- When an image is distorted, spatial resolution is also reduced
- Types of distortion
- Size Distortion
- Shape Distortion
DISTORTION
