MILLIONS of people with thyroid disease are being given excessive doses of radiation that could increase their risk of contracting cancer. That鈥檚 the conclusion of the Swedish Radiation Protection Authority (SSI), which says many hospitals around the world are ignoring international recommendations to minimise patients鈥� exposure to radiation.
Up to 5 per cent of women and a much smaller proportion of men contract Graves disease, an immune system defect causing the thyroid gland to produce too much hormone. For 50 years the disease has been treated by destroying all or part of the gland with radioactive iodine-131.
But Helene J枚nsson, an SSI inspector, says doctors fail to optimise the radiation dose for individuals, as they do with X-rays and CT scans. 鈥淲ith iodine therapy, they don鈥檛 care,鈥� she told 快猫短视频. 鈥淚t is a concern.鈥�
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Patients are commonly given a fixed amount of iodine-131, often 370 megabecquerels, without taking into account the size of the thyroid gland, the amount of iodine it takes up and the amount it loses, J枚nsson says. All of these can vary widely, and J枚nsson is particularly worried about young people being treated in this way because their chances of developing cancer as a result in later life are higher. She says some children in the US have been given large fixed doses of iodine-131, which she describes as 鈥渉orrible鈥�.
To test how much difference it makes to calculate the dose individually, J枚nsson analysed 187 cases of Graves disease at Malm枚 University Hospital between 1984 and 1988 in which doses of iodine-131 were individually optimised. She worked out that if the patients had instead been exposed to a fixed 370 megabecquerels they would have received an average of two-and-a-half times as much radiation as they needed (Radiation Protection Dosimetry, vol 108, p 107).
That, J枚nsson argues, would breach the recommendation by the International Commission on Radiological Protection to keep radiation exposure 鈥渁s low as reasonably achievable鈥�. For countries in the European Union, it would also be a breach of a 1997 directive protecting people against the dangers of medical radiation.
Keith Baverstock, an expert on radiation and health at the University of Kuopio in Finland, agrees there is cause for concern. 鈥淚odine-131 is highly toxic to young children, increasing the risk of thyroid cancer even at low doses,鈥� he says.
Dan Ash, president of the Royal College of Radiologists in the UK, agrees it is important to keep radiation doses as low as possible. 鈥淚t is likely that some patients will get more than they need,鈥� he says. 鈥淏ut that is better than failing to treat the disease, especially when there is no proof that the treatment causes long-term damage to health.鈥�