Dr. Tsubokura's Radiation Lecture Vol.9

Author: Masaharu Tsubokura

Editors: Akihiko Ozaki M.D., Yuki Senoo

17. Examinations for "Internal exposure" and "External exposure" are different

Do you know what happens when you get a Whole-Body Counter examination immediately after taking X-ray and CT scan?

The answer is "nothing will be detected."

If you are wondering "Wait, huh?", let's take a look back on the relationship between radiation and radioactive substances.

We receive exposure from radiation emitted from radioactive substances.X-ray and CT scans correspond to "external radiation exposure" where our body is exposed to the radiation from an external source. They are, therefore, not a type of medical examination causes internal contamination of radioactive substances into our body.

On the other hand, Whole-Body Counter is an examination for detecting "internal radiation exposure". This means the device can detect whether radioactive substances, not radiation, are present inside our body.The levels of "external radiation exposure" and "internal radiation exposure" are examined and evaluated differently. The sum of both reflects the effect on our body.

For the detection of external radiation exposure, it is necessary to measure right at the moment of being exposed. Contrarily, the radioactive substance remains inside the body for a certain period; thus, the check-up can evaluate the level of internal exposure even after a while since the time of exposure.

18. The evidence for "safe local food"

There were only very few people from whom radioactive cesium was detected by Whole-Body Counter, an examination device for assessing internal radiation exposure.

In Minamisoma, a city in Fukushima Prefecture, examination for internal radiation exposure was conducted with more than 3,000 students, which covers 99% of Minamisoma city' s primary and secondary school in 2014. In this examination, they did not detect radioactive cesium in any of the candidates. Besides, there was another examination conducted with nearly 2,000 infants in the same region using the examination device specially designed to detect cesium more precisely called Baby Scan. In this research, radioactive cesium was also not detected from anyone.

"Radioactive cesium is not accumulated inside of the residents' bodies. This result was obtained by under the condition which a vast majority of the candidates were consuming the food and tap water from the region. Besides the inspection results of the food itself, the results mentioned above are exhibiting the safety and the appropriateness of protection for the circulating food and the food consumed within the prefecture. ---------------------------------------------------------------------------------------------------------------------------------------

The Japanese version of the manuscript was originally published in Fukushima Minyu, a local newspaper in Fukushima prefecture, Japan, on May 3rd and 10th 2015, and was reproduced for MRIC Global under the author's permission.