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.

263. 骨の状態を放射線で検査






264. 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.

264. 放射線の使いすぎは問題






The Japanese version of the manuscript was originally published in Fukushima Minyu, a local newspaper in Fukushima prefecture, Japan, 2 Feb and16 Feb 2020 was reproduced for MRIC Global under the author's permission.

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