MEDRADSC 2AA3 - Lecture 1.3 - Digital Image Production Cont

spatial frequency

number of line pairs per unit distance

the higher the spatial resolution, the higher the _____________ __________ and the greater the number of line pairs.

spatial frequency

higher spatial resolution is ideal in order to be able to better visualize structures and accurately diagnose patients, but with higher spatial resolution, there are downsides. What are they?

when you increase the spatial resolution of an image, you increase the matrix size, which means that there is more information to be stored and therefore takes up more storage

what information is stored in the image matrix for radiography?

intensity and position of signal

what effect does increasing spatial frequency have on sampling frequency?

when you increase the spatial frequency, you increase the sampling frequency

what is the dynamic range?

the range of signal intensities that an imaging system can respond to

what does window width represent?

contrast

what does window level represent?

brightness

what affects the shade of grey assigned to a pixel?

signal level

what are the two types of contrast on a diagnostic image?

intrinsic and displayed contrast

intrinsic contrast

detected interfaces based on differences in signal intensity

displayed contrast

the signals/shades of grey displayed on the monitor to form the image, may be amplified/windowed

what imaging modality has the best contrast resolution?

MR

what imaging modality has the best spatial resolution?

mammography

what imaging modality has the worst contrast resolution AND spatial resolution?

nuclear medicine

nuclear medicine is known to have the worst contrast resolution AND spatial resolution between modalities, why is this and why does it not necessarily matter as much in nuclear medicine?

the prime function of nuclear medicine is to examine the physiology of the body, so it is not needed to demonstrate specifics of the body, just their functioning

modulation transfer function (MTF)

the ability of a system to demonstrate structures and information regarding structures

a large structure has a ________ modulation transfer function (MTF)

large

higher spatial frequency means __________ modulation transfer function (MTF)

higher