Medical Imaging

What is an image? ● An image is a function – from a spatial or temporal domain – into a two, three, or four dimensional space – such that the function value can be seen

Understanding Images ● To understand an image one must – know the input domain – know the output domain – know the function value ● What does an image represent? – You must look at what each pixel represents based on the above criteria

Photography ● Photography images the three-dimensional world onto a two-dimensional plane – early photography was monochrome ● intensity was a function of ambient lighting ● intensity was a function of spectral sensitivity – the function value can be color (ideally same as input) – images are scaled in most cases

Maps ● Historically maps scaled and distorted the curved surface of the earth onto a smaller flat plane ● Modern maps combine multiple sources of information about the earth ● Features are represented by – color – shading – texture – geometric shapes

Medical Imaging ● How can we see inside a person? ● Can we diagnose disease from images? ● Can we monitor progress of healing?

Challenges ● Patient health ● Patient comfort ● Motion of patient ● Motion of internal features ● Cost

Types of Medical Imaging ● Transmission – X-rays – Nuclear Medicine ● Reflectance – Ultrasound – Photography ● Slice (can produce 3D images) – CT – MRI – PET – SPECT