Download contrast microsoft

Contrast is defined as the many shades of gray on a radiographic image. A long scale of gray is termed
low contrast where as a short scale of gray is termed high contrast.
What determines how many shades of gray there are on an image are a plethora of factors. Those
factors are categorized by how they effect the image. There are controlling factors such as kVp which
is the primary controlling factor of contrast. Kilovoltage Peak, other wise known as kVp, will affect
subject contrast. Subject contrast is determined by the patient thickness and density. If a patient is
muscular, thin, fat, old, or young. Each type of patient has a different level of anatomic absorption
possible. Each type of patient will have a different level of subject contrast innately possible on the xray image taken. With a patient who is thicker you have increased amounts of scatter possible and a
decrease in the amount of contrast possible. Thus by using a grid you will increase the amount of
contrast and decrease that potential scatter.
Leading me to other influencing factors such as wether or not a grid is used when taking the image. If
a grid is used when taking the image, lets say you are taking a picture of a body part that is typically
filled with tissue instead of bone, then you will increase the amount of contrast on the image and
decrease the amount of scatter that could have been on the image. This is a very good thing.
Other influencing factors are collimation, OID, anatomic part thickness, tube filtration, induction of a
contrast medium. With increased collimation, meaning you are making the field size smaller, then you
have increased contrast and decreased scatter. With increased OID you will increase contrast and again
decrease scatter. As you can see when ever you increase the amount of contrast possible on an image
you are going to an indirect relationship with scatter. Accordingly when you decrease scatter you are
decreasing the amount of noise on the overall image and increasing the overall quality of the image as a
whole.
When speaking of digital imaging and contrast the biggest contributing factor is kVp. Kilovoltage
Peak will determine how well the anatomic tissue is penetrated. Which makes it the primary
controlling factor of contrast both in digital imaging and in film screen imaging. Other factors that
affect contrast on a digital image is window width. When you increase window width you will
decrease contrast, ie: low contrast, long scale of gray. The computer monitor with its pixel depth,
matrix size which will affect the contrast resolution. Contrast resolution is the level of visibility on a
monitor. The varied shades of gray that can be seen by the human eye. The greater the pixel depth the
greater the number of shades of gray possible.