The Associated Press

EVANSVILLE, Ind. - A 9-year-old girl undergoing a thyroid scan was mistakenly given a radioisotope dosage 100 times greater than what her doctor had prescribed.

The patient's family was not told of the error until Friday, after Deaconess Hospital officials were asked about it based on information from the Nuclear Regulatory Commission's Web site.

"We are diligently investigating the cause of the dosing discrepancy, and we are already in the process of implementing corrective action to prevent a recurrence," said Michael Hart, a Deaconess spokesman.

The names of the patient and the physician were not disclosed.

Hart said the physician delayed notifying the family of the March 28 error because it was not expected to have a "significant adverse health effect" and the doctor wanted to tell them in person.

According to information from the Nuclear Regulatory Commission, the 9-year-old patient was given 400 microcuries of I-131 when the child had only been prescribed 4 microcuries of I-131.

"The error occurred when the patient couldn't swallow the capsule and the hospital ordered a liquid form of the radioisotope," the Web site stated. "The wrong dosage was ordered from the radiopharmacy. The error was not discovered until after the dosage had been administered."