Your notes are important and should be back up when possible. Pieces of paper can get lost, spilled on, and destroyed in several different ways. But for some of us, paper is still where we take notes, make comments, etc. Always save digital images of those paper notes that you make.
You do not want to have to repeat that process of researching over and over again. So this is a way to back up your research and to have access to those notes later when your files are not available. A digital image is a great way to do that. Make certain that you get the whole page when taking the picture.