Dr. Tsubokura's Radiation Lecture Vol.133

Author: Masaharu Tsubokura PhD.

Editors: Akihiko Ozaki M.D.,PhD., Yuki Senoo



265. Excessive exposure to radiation causes issues


Today, radiation is widely used in modern medicine, from disease diagnosis to treatment. The use of radiation in medicine is increasing every year worldwide. Japan is known as one of the countries with an excessive radiation dose received from medical procedures.


Of many nuclear medicine radiodiagnostic procedures, CT scans, in particular, account for a large portion of the medical radiation exposure. Furthermore, along with the U.S., Japan has the highest number of CT scanners in the world. Japan has over five times more CT scanners than that of most European countries. Besides, with the advancement of technology, a full-body scan is completed in a short time. As a result, the total number of CT examinations and the number of examinations per patient has increased in Japan.


Generally, the higher dose of radiation is used in a CT scan, the clearer the images become, allowing to perform a detailed examination. From the practitioners' point of view, a clear image produced using a high dose of radiation is preferable. On the other hand, using an excessive amount of radiation in pursuit of clear images may cause problems.


This provides motivation for further technological development aiming to produce high-quality images at the same time to reduce the radiation dose.

266. The optimal use of radiation


The government sets the regulatory dose limit for ionizing radiation that workers are exposed to while performing their duties. Occupational groups that are routinely exposed to radiation include coal miners, who usually work in areas of high natural radiation, airline crews, workers at nuclear power plants, physicians, nurses, and radiology technicians. Currently, the effective dose limit for occupational exposure is 50 millisieverts/year and 100 millisieverts on average over five years.


In contrast, there is no dose limit for radiation exposure relating to medical examinations or treatment among patients. In other words, medical necessity is the only factor taken into consideration when deciding whether patients should undergo medical examinations and treatments using radiation.


Medical examinations and treatments using radiation are some of the most effective procedures to diagnose and treat certain diseases. Due to their benefits and effectiveness, the use of medical radiation is trending upwards around the world, including Japan. In fact, Japan is one of the top countries in terms of radiation exposure relating to medical care. Since there are no regulations limiting radiation exposure from medical examinations and treatments, it is crucial for healthcare professionals and patients to carefully discuss the advantages and disadvantages of each examination and treatment

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The Japanese version of the manuscript was originally published in Fukushima Minyu, a local newspaper in Fukushima prefecture, Japan, 16th and 23rd Feb was reproduced for MRIC Global under the author's permission.

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