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Dr. Tsubokura's Radiation Lecture Vol.8

Author: Masaharu Tsubokura

Editors: Akihiko Ozaki M.D., Yuki Senoo

15. The role of total dose in radiation effect

If we compare guzzling a bottle of wine in one go to sipping on it for a year, it is unquestionable that the former would be more dangerous to our health.

This goes the same for radiation effect as well.

In the case of being exposed to "the same total dose of radiation," longer exposure time has less effect to our body than shorter exposure time, although it sounds awful to be exposed for an extended period of time.

It is important to note that this only applies under the condition of consuming "the same total amount" of alcohol. Spending 10 days to drink a bottle of alcoholic beverage has the less physical burden on our body than spending 1 day.

How about drinking a bottle in 1 day (total amount of 1 bottle) and drinking 10 bottles in 10 days (1 bottle/day)? Of course, the case of consuming 10 bottles has more effect on one's health.

Radiation effect depends on the dose of exposure. It is, therefore, necessary to know the total amount of the exposure dose. Given this fact, when it comes to the same total dose of radiation, longer exposure time has less effect on our body.

16. Medical Uses of Radiation in Diagnosis and Treatment

Hospitals utilize radiation for diagnosis and treatment.

I suppose some of you have had the experience of undergoing a CT scan and an X-Ray examination. These devices produce images by exposing ionized radiation on our body and sensitizing a metal film. In chest X-rays, we will be "externally exposed" to approximately 60 microsieverts (0.06 millisieverts) and in chest CT scan around 7000 microsieverts (7 millisieverts) of radiation dose each time.

Besides that, there is a PET examination in which the applicant is required to intake glucose with radioactive material to diagnose cancer. This method based on the nature of cancerous cells to take in glucose more than normal cells. In this examination procedure, you will be "internally exposed" to radiation.

On the other hand, a Whole-Body Counter is a machine that detects radioactive substances in the body by placing a large detector device close to the body to pick up small amounts of radiation leaking out of the body.

Therefore, you will not be exposed to radiation in this procedure "at all." ---------------------------------------------------------------------------------------------------------------------------------------

The Japanese version of the manuscript was originally published in Fukushima Minyu, a local newspaper in Fukushima prefecture, Japan, on April 19th and 26th 2015, and was reproduced for MRIC Global under the author's permission.

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