KOFU, Japan - A local hospital said on Thursday one of its radiographers had deliberately administered higher-than-recommended amounts of a radioactive substance during examinations of 84 children suffering from kidney ailments since 1999.
Kofu Municipal Hospital said the radiographer intravenously injected a test agent containing radioactive technetium-99m into the children, aged 15 years and younger, between May 1999 and April this year. The amounts exceeded the dose recommended for an adult by the Japan Society of Nuclear Medicine, according to the hospital.
According to hospital director Katsura Ozawa, technetium-99m is a metastable nuclear isomer of technetium-99. The agent tends to concentrate in the kidneys and when intravenously administered, allows clear images to be taken during x-rays. The test agent is designed to examine the functioning of recipients' internal organs.
No health problems from the children's radiation exposure have been reported.
Of the 84 children, 41 were given amounts over 10 times the society's recommended dosage for their age group, with one child's total internal exposure suspected to be 180 millisieverts, the hospital said.
The society recommends 185 megabecquerels as the maximum dosage for adults. For patients aged under 15 years, the dosage is reduced according to their age.
According to guidelines set by the society, doctors should decide the amount of the test agent to be administered. However, a male medical radiographer at Kofu Municipal Hospital had been determining the amount without consulting with other staff, hospital officials explained.
The radiographer reportedly told the hospital he knowingly gave higher doses of the test agent to the children so clear images could be taken as quickly as possible.
Prof. Norinari Honda, department of radiology and radiology service at Saitama Medical Center, Saitama Medical University, said: "While it is sometimes necessary for doctors to conduct these types of examinations, it is a basic principle that patients are subjected to the minimum amount of radiation possible."