Dear Medical Programmer:
One has to recognize that college education focuses on developing skills and knowledge in certain specialized areas, whereas certain jobs may require combination of skills, knowledge and experience from multiple fields. Not every combination of skills required for every job in the marketplace is offered as a custom package in a college/university program.
You can pursue a Master's degree in computer science. However, this program will focus on software development, and not on software development for the medical field. For details about getting a Master's degree in the US, iMahal offers an
Authoritative Guide on Studying in America and Canada. Also, the
iMahal Education Channel offer List of Colleges in Computer Science in the US and UK. The
iMahal Guide details the admission requirements and process, as well as how you can improve your chances of success.
Software development for a particular field does not necessarily require the knowledge of that field. Experts in the field educate the software developer about the functional requirements of the software, and the developer can typically create software from this knowledge alone. For example, software developers for applications in mathematics are not mathematicians, and software developers for movie productions - say, Star Wars or Toy Story - are not film directors or producers.
In a nutshell, experts in the medical field are needed to produce functional requirements and the software developers are needed to implement the functional requirements. We suppose that you wish to have expertise in both fields, and that is your choice. In our view however, you do not necessarily need expertise in both to be successful in the medical software development arena.
We are not quite sure how to address your question on the future prospects of "research" in the medical software development. It is inevitable that research will continue in the medical filed, as well as in the field of software development. Wherever appropriate, the research in both fields will be leveraged to design medical software.