Have a look into the Mathematica Help Browser located in the Mathematica help menu. There you find a function index with examples and several introduction notebooks explaining the basics and some tips and tricks.
A new addition to MathVisionTools is an introduction to image conversion by Edwin Bennink. He explains how to import different medical image formats and how to export them in DICOM. Edwin Benninks notebook is located in the Mathematica Help Browser under Add-ons>MathVisionTools>Introduction, Tips, and Tricks>Image Conversion.