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Dr. Tsubokura's Radiation Lecture Vol.132

Author: Masaharu Tsubokura PhD.

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

263. Diagnostic radiology examination used to measure the bone condition

As with radiotherapy used to treat cancer, internal and external radiation sources are used in radiographic examinations routinely conducted at hospitals. For instance, X-rays and CT scans are examples of radiation diagnostic techniques using external radiation sources.

On the other hand, there are several imaging techniques that use internal radiation sources to deliver radiation. The previous article introduced a PET scan as one of the examples of such examinations. In a PET scan, glucose labeled with radioactive isotope is injected into the body. The radioactive glucose emits a small amount of radiation, which then a PET scan detects its concentration and location to diagnose the caner.

Similar to a PET scan, bone scintigraphy is used to evaluate the condition and disorder of bones. In this examination, small amounts of radioactive materials that accumulate rapidly in bone, radiotracers, are injected into the bloodstream. A few hours later, a special camera placed outside of the patients’ body will capture the radiation emitted from the radiotracers accumulated in the bone.

A Scintillation detector, which uses fluorescent materials that glow when exposed to radiation, is often used to measure the radiation dose rate. The same method is applied to bone scintigraphy to detect radiation emitted from the radiotracer accumulated in bones inside the body. Furthermore, this imaging technique is called "bone scintigraphy" since an image showing which bone has increased or decreased radiotracer uptake.

264. Japan: The world’s top investor in nuclear medicine procedures

Radiation is widely used in modern medicine. Its applications range from diagnostic techniques to the treatment of certain diseases. The use of ionizing radiation in medicine is increasing worldwide, and Japan is well known as one of the top countries with a high level of medical radiation exposure.

The level of radiation received varies from person to person depending on whether they have undergone medical examinations using radiation in hospitals or elsewhere. In Japan, the average annual medical radiation exposure dose is approximately 3.9 millisieverts. By comparison, the average annual radiation exposure from naturally occurring radiation is about 2.1 millisieverts. Therefore, in Japan, people receive a higher level of radiation exposure from medical procedures than from naturally occurring radiation. Furthermore, X-rays and CT scans, excluding routine chest X-rays and barium enemas conducted during health checkups, account for most medical radiation exposure. In addition, the total annual number of CT examinations and the number of examinations per patient are both rising in Japan.

Nevertheless, CT examination is one of the essential imaging techniques used in modern medical practice to diagnose and treat patients accurately. Although patients should refrain from receiving unnecessary CT examinations that have no clear benefit, it is too extreme to avoid all medical examinations that use ionizing radiation. It is essential to discuss the advantages and disadvantages of undergoing radiological examinations with your physician and to identify the best option.


The Japanese version of the manuscript was originally published in Fukushima Minyu, a local newspaper in Fukushima prefecture, Japan, 2 Feb and 9th was reproduced for MRIC Global under the author's permission.


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