Journal: Improving my math skills

As a high school drop-out, here on Spain,I never made too much into maths. I began early to work (at 16 years old), and now, 12 years later, I'm an amateur photographer, I'm a 'nice' sysadmin and a good IT technician, I can survive speaking english and a pair more of languages, but I'm entering a new field I would love to master: medical and scientific imaging. The thing is, as soon as you begin studying image analysis or magnetic resonance you see that the basic arithmetic you learnt isn't enough for this. I just know basic arithmetic, statistics, sci. notation, boolean algebra... but no calculus or applied math (and beyond). I know some physics already, due to my work around scientific imaging, and my science hobbies, and would like to know more, but I see math as my biggest barrier now. So, what would be you advice to improve my math in a way that would be helpful to my magnetic resonance and image analysis crazyness?