An oncologist blamed for botching cancer treatments at the Philadelphia Veterans Affairs Medical Center says he's not the rogue physician he's been portrayed to be.

Dr. Gary Kao is testifying at a congressional hearing at the medical center in Philadelphia. He says the prostate cancer treatment, which involves implanting radioactive seeds, "was and still is an evolving field."

According to a Nuclear Regulatory Commission report, 92 veterans received incorrect radiation doses at the hospital over a three-year period. Some patients had seeds implanted in the wrong places.

Kao says he was instrumental in setting up the program and never falsified results or covered up mistakes.

U.S. Sen. Arlen Specter, a cancer survivor, called Monday's hearing.