if you have done your Under Graduation in technology(B.TECH) Then it is possible to do PG Degree in M.Tech bio medical engineering. however some Institutions may demand an UG Degree in medical field or biology field. it depends upon the institution you choose to do your post graduation and the courses offered there. but there is more possibility to get a M.Tech course with bio subdivision like you asked (bio-medical engineering or environmental engineering). And the job opportunities after completing your PG degree shall have high demands of internships in the field you ask for job.