DR.TSUBOKURA'S RADIATION LECTURE VOL.159

Author: Masaharu Tsubokura M.D., PhD.

Editor: Yudai Kaneda


317  Radioiodine Dosage Treatment

March 6, 2021


The thyroid gland is a small, butterfly-shaped organ, about 10-20 grams, slightly below the middle of the neck (below the throat). A malignant form of the disease that causes a lump to form in a part of the thyroid gland is called thyroid cancer. Most frequent radiation-related thyroid cancers are of a type called papillary carcinoma. The basic treatment for papillary thyroid cancer is surgery.


However, a non-surgical treatment involves taking capsules containing radioactive iodine. Our thyroid gland uses normal (non-radioactive) iodine as a resource to make hormones that regulate metabolism. Because the body cannot distinguish between normal iodine and radioactive iodine, when radioactive iodine enters the body, it is taken up by the thyroid gland or by the thyroid cancer, which resembles it. The radioactive iodine taken up by the thyroid cancer then emits radiation that can attack the cancer cells in the area nearby.

After that, the amount of radioactive iodine decreases and it is excreted from the body. It is known that the amount of radioactive iodine actually used in the treatment is much more than the amount of radioactive iodine that might have entered a person’s body after the nuclear accident.


However, the mechanism of this treatment using radioactive iodine is the same as what happened immediately after the nuclear accident.

318  Medical Treatment, Usually Iodine Restriction

March 13, 2021


The primary treatment for papillary thyroid cancer is surgery, but after the surgery, the patient can take capsules containing radioactive iodine.


Because the body cannot distinguish between normal and radioactive iodine, when radioactive iodine enters the body, it is taken up by the thyroid gland or by the thyroid cancer, which resembles it. The radioactive iodine taken up by the thyroid cancer then emits radiation that can attack the cancer cells in the area nearby.


This treatment does not work if too much normal iodine is already in the body, because when too much normal iodine is in the body, the body does not need more iodine, so the radioactive iodine for the treatment is not taken into the body.


Therefore, before treatment with radioactive iodine capsules, it is necessary to restrict the diet from containing too much normal iodine for 1 or 2 weeks. This is because the food we eat in Japan, including seaweed such as kelp, contains excess normal iodine.

If one does not limit the amount of normal iodine from the diet appropriately, the effect of treatment with radioactive iodine will be weakened. Because the Japanese diet is high in normal iodine, it had the effect of making it difficult for people to take in radioactive iodine during the recent nuclear accident. This is one of the major differences from the Chernobyl accident.

 

The Japanese version of the manuscript was originally published in Fukushima Minyu, a local newspaper in Fukushima prefecture, Japan, on 6 and 13 March 2021 was reproduced for MRIC Global under the author's permission.




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