Some 55 prostate cancer patients were given too-low doses of radiation treatment at the local Veterans Affairs hospital in the past six years, and federal investigators want to know why.
The Nuclear Regulatory Commission announced Tuesday it is inspecting the Philadelphia VA Medical Center's facilities and procedures to figure out what went wrong and how to prevent it from happening again.
The treatment program, which started in February 2002, remains suspended while the investigation is under way, officials said.
The VA is also evaluating the cases of affected patients to see what kind of additional care they may need.
The men had radioactive seeds implanted in the prostate to destroy cancer cells, but it was discovered that they received dosages that were less than what had been prescribed for them.
Experts say most men who undergo only that type of treatment have low-risk prostate cancer.
Hospital officials had announced the possible underdoses in July. Officials had said they were reviewing records of 114 cancer patients to see which ones might have received the wrong radiation dosage. Hospital spokeswoman Fern Billet said last month that two of the 114 patients had died, but it was not clear if the feared error played any role in their deaths.