ABSTRACT
Convolution is a mathematical method for describing how a system transforms an input signal into an output signal. This technique was developed by electrical engineers. This chapter describes a number of systems which can be described using the concept of convolution and examines how this process can be written mathematically. Convolution can be used to describe many everyday radiologic processes. The chapter provides an example of convolution using an input signal composed of two delta functions. Convolution integral provides a formula for calculating the output of a system to any input as long as the system functions. Most of the applications of interest to a radiologist involve two-dimensional convolution of images. Most image processing problems use or can be described using two-dimensional convolution. Two-dimensional convolution is very similar to one-dimensional convolution. Some of the examples of convolution are: lung time activity curve, X-Ray cassette, audio amplifier, and radioactive decay.
