A man from the U.K. has become the first person in the world to undergo revolutionary heart surgery using radiation.

Michael Kilby was told he may only live until Christmas after doctors discovered a tumor larger than the size of a golf ball in the right chamber of his heart, U.K.’s Daily Telegraph reported. The size of tumor was blocking blood flow.

The 67-year-old underwent surgery, radiotherapy and chemotherapy, but nothing was improving his condition. It was at this point that doctors at the Harley Street Clinic, in London, turned to surgery involving a radiation “scalpel,” called the Cyberknife, to cut away the tumor inside his beating heart.

The Cyberknife is already used to treat tumors located throughout the body including the prostate, lung, brain, spine, liver, pancreas, head and neck. But this is the first time it has been used in heart surgery.

"I was treated for five days with each session lasting for about an hour and a half,” Kilby told the newspaper. “You cannot feel anything at all, it’s just like radiotherapy.”

As a result of the treatment, doctors said the tumor has shrunk significantly and they expect to shrink even further in coming weeks.

The Cyberknife is a non-invasive alternative to surgery for the treatment of both cancerous and non-cancerous tumors anywhere in the body. The treatment works by delivering beams of high dose radiation to tumors with extreme accuracy. The treatment does not involve any cutting and is the world’s first and only robotic radiosurgery system designed to treat tumors throughout the body non-invasively, according to www.cyberknife.com.

Click here to read more from the Daily Telegraph.