i wanted to be a doctor but we know that medical colleges are so expensive now i am doing my graduation in computer science is there any subject which connects the two ie:- the subject in which I use my computer science knowledge in medicine
There are many ways you can use computer science in medicine. If you are interested in clinical research or the application of software to the practice of medicine, look into Medical Informatics (sometimes called Biomedical Informatics). There are many applications of CS in the clinic, such as developing medical record systems, mining records to improve patient care, databases of samples from pathology clinics or biobanks, etc. On the more translational side, depending on your research interests and statistical background, clinical trials often need people skilled with software (but most particularly people with real statistical knowledge).
You could also say that directly or indirectly all of bioinformatics is the application of computer science knowledge to problems in medicine, if you broadly define medicine to include basic knowledge as well as translational research. For more information jobs in bioinformatics, see posts tagged with "career".
The world of informatics is quite vast. It is usually intertwined with other traditional fields to cater the changing needs in those fields. There are several related fields that you may want to choose from to focus on:
Medical Informatics - discipline that has been defined as the study, invention, and implementation of structures and algorithms to improve communication, understanding and management of medical information.
Health Informatics - deals with the resources, devices, and methods required to optimize the acquisition, storage, retrieval, and use of information in health and biomedicine. It applies to the wide areas of nursing, clinical care, dentistry, pharmacy, public health, occupational therapy, and (bio)medical research.
Pharmacy Informatics - field that focuses on medication-related data and knowledge within the field of healthcare systems impacting on patient care and management.
Biomedical Informatics - science of information as applied to or studied in the context of patho-physiological processes with methods from biology, chemistry and physics.
Pharmacoinformatics - Implementation and use of information technologies for the discovery and development of drugs as well as in pharmacy education.
Cheminformatics - use of computer and informational techniques, applied to a range of problems in the field of chemistry; more relevantly in the drug discovery process in the healthcare field.