I think that you will find many different answers to this question, and so sifting through them will be the most challenging part. I would say that one specific major event would be the passage of the President's health care bill. If nothing else, it is the first significant legislation on health care to be passed in such a manner. Like it or not, the bill represents a significant moment in the history of health care in our nation. Another significant event would be the development and emergence of health care management, or HMOs. The substitutions of major hospitals providing health care services and the emergence of these organizations are significant to the health care in the last fifty years. I would say that the development of preventive care is also another major issue in health care. Developing patterns of "healthy behavior" has become a significant focal point of modern health care. Malpractice insurance is another reality that has emerged in the last fifty years, as doctors and insurance companies now live with the threat of being sued over just about anything. As with so much, the web has transformed health care. Sites like WebMD have made the average patient much more savvy sounding and have forced professionals to have to qualify diagnoses and explain elements in more critical terms as knowledge increased, while understanding might not have.
HIPAA (HEALTH INSURANCE PORTABILITY AND ACCOUNTABILITY ACT). Provides medical patient security for medical records.
ELECTRONIC MEDICAL RECORDS. The near elimination of paper filing allows for instant access to patients' records.
AIDS. The worldwide epidemic has been met with drug cocktails which now allow patients to live a longer life.
ABORTION. The legalization of abortion has provided safer procedures from licensed physicians.
WOMEN DOCTORS. A rarity in 1961, women doctors are now common.
ARNPs (ADVANCED REGISTERED NURSE PRACTITIONERS & PAs (PHYSICIAN'S ASSISTANTS). Uncommon or non-existent a half-century ago, these licensed practitioners now both assist physicians and handle patients on their own.
ARTHROSCOPIES. Physicians now have the ability to give less invasive procedures on an out-patient basis without admission to hospitals.
X-RAYS. More advanced imaging is now common thanks to MRIs and Cat Scans. Physicians can now read x-rays on a disc, eliminating the paper x-ray--a big cost-saver for patients.