FILM MODULE 4 Flashcards
refers to the fidelity with which the anatomical structure that is being examined is rendered on the radiograph.
radiographic image quality
A radiograph that faithfully reproduces structure and tissues is identified as a
high quality radiograph
To produce high-quality images, radiographers apply knowledge of the three major interrelated categories of radiographic quality
factors, geometric factors, and subject factors.
The most important characteristics of radiographic image quality
resolution, contrast resolution, noise, and artifacts.
is the ability to image two separate objects and visually distinguish one from the other.
redolution
refers to the ability to image small objects that have high subject contrast, such as a bone–soft tissue interface, a breast microcalcification, or a calcified lung nodule.
spatial resolution
is the ability to distinguish anatomical structures of similar subject contrast such as liver–spleen and gray matter–white matter.
contrast resolution
is a term that is borrowed from electrical engineering
noise
The flutter, hum, and whistle heard from an audio system constitute audio noise that is inherent in the design of the system.
noise
is the random fluctuation in the optical density (OD) of the image.
radiographic noise
refers to the distribution in size and space of silver halide grains in the emulsion.
film graininess
is similar to film graininess but refers to the phosphor of the radiographic intensifying screen.
structure mottle
to the random nature by which x-rays interact with the image receptor.
quantum mottle
somewhat under the control of the radiologic technologist and is a principal contributor to radiographic noise in many radiographic imaging procedures.
quantum mottle
NOTE
The use of high-mAs, low-kVp and of slower image receptors reduces quantum mottle.
term used to loosely describe the sensitivity of film to x-rays. Resolution and noise are intimately connected with speed.
speed
if the image receptor is fast what will be the noise and spatial resolution, and contradt
high noise, lowspatial reso and low contrast
study of the relationship between the intensity of exposure of the film and the blackness after processing.
sensitometry
H & D curve
Hurter and Driffield
The two principal measurements involved in sensitometry
exposure to the film and the percentage of light transmitted through the processed film.
Base plus fog OD has a range of approximately
0.1 to 0.3
All images on the radiograph are larger than the objects they represent, a condition
magnification
The ability of an image receptor to respond to a low x-ray exposure is a measure of its sensitivity or, more commonly,
speed
It refers to the range of exposures over which the image receptor responds with ODs in the diagnostically useful range.
latitude
Three principal geometric factors that affects radiographic quality:
1.Magnification
2.Distortion
3.Focal-spot blur
relationship of Latitude and contrast
inversely proportional
agnification is desirable and is carefully planned into the radiographic examination. This type of examination is called
Mmagnification radiography
Unequal magnification of different portions of the same object is called
shape distortion
Distortion depends on:
- Object thickness
- Object position
- Object shape
most important factor for determining spatial resolution
focal sot blur
what is the size of the focal spot blur in anode and cathod side
anode small
cthode large
