Dear Sayan, there are 2 ways to go about becoming a Radiologist. The basic eligibility criteria remains the same. You should have completed your 10+2 with a minimum aggregate of 50% with Physics, Chemistry and Biology/Biotechnology as your core subjects. 

• Appear for NEET, complete your MBBS and then appear for NEET PG and pursue MD Radiology. This will take approximately 7-8 years from now. Pros are that you will be a Doctor and can have your private practise. The salary that you get here is more because of the Academic qualification that you have got.
• Take up a 3 year B.Sc Radiography course and then start working right away while being associated with a Private Hospital, Clinic or nursing home. You can work either independently or work in any clinical setting. You may get paid anywhere from 7000Rs to 10000Rs initially and the salary range will increase as you put on years of experience. Few Institutions conduct entrance examinations for admission while few Institutions conduct admissions based on merit scored in 10+2.