You'd need at least a Master's Degree in business management. First thing to realize is that you would not be the person operating the machines but rather the business manager of the establishment. You'd need sufficient funds to hire at least two board certified M.D. radiologists and a staff of technologists. Imaging machines are quite expensive - you'd need about ten million dollars to purchase and install them. Among said machines are ultrasound, diagnostic x-ray machines, CAT scanners and MRI machines. A major health center will also benefit by having a PET scanner. There are also the devices that use diagnostic nuclear medicine. Technologists to operate them and specialists to maintain them are essential - and all of them are maintenance-intensive.
In short, you're looking at a major investment - which as an individual you're very unlikely to be able to do - even if you win the lottery. Such centers invariably demand the cooperative effort of a number of highly qualified and well-funded entities, not the least of which are major teaching hospitals and well-established medical clinics.