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Dr. Tsubokura's Radiation Lecture Vol.91

Author: Masaharu Tsubokura

Editors: Akihiko Ozaki M.D., Yuki Senoo

181. Rontgen, the father of diagnostic radiology/X-rays

There are many technical terms related to the field of radiation, such as Becquerel, Sievert, and X-ray (In Japanese, X-rays are called Roentgens). Many of these words are derived from the names of scientists who made significant contributions to radiation-related research.

For example, in 1895, Wilhelm Rontgen, a German physicist, conducted an experiment to evaluate a quality of an electric current passing inside an evacuated glass tube. This experimental device became a prototype for a cathode-ray tube built in an old TV.

During this experiment, Rontgen noticed that a fluorescent plate placed near the glass tube was glowing, even though the glass tube was tightly covered with black paper. In observing this phenomenon, he hypothesized that "something invisible" was coming out of the glass tube and causing the fluorescent screen to glow. He named that "something invisible" an "X-ray," as the letter "X" is often used in mathematics to mean an unknown value.

In a paper published immediately after this discovery, he reported that X-rays were almost entirely shielded by a lead plate, that the intensity of the X-rays decreased with distance, and that it was possible to visualize bones using X-rays. This discovery of X-rays was immediately spread throughout the world. As many of you may know, X-ray is still used in medical practice today.

For his astonishing discovery, Rontgen received the first Nobel Prize in physics in 1901.

182. An English physicist who named the gamma ray

Thanks to the achievements of scientists such as Becquerel, Curie, and Rontgen, radiation-related research has made significant advancements since the end of the 19th century.

All materials are composed of small invisible particles called protons, neutrons, and electrons. Furthermore, in every material, protons and neutrons form a cluster (nucleus) with electrons rotating around it.

When the numbers of each type of particle are imbalanced, the substance as a whole becomes unstable and emits extra protons, neutrons, electrons and energy to stabilize itself. These emitted particles are radiation. According to their manner of emission, radiation rays are categorized into alpha, beta, or gamma rays.

In 1898, Ernest Rutherford, a New Zealand-born British physicist, discovered that there are two types of radiation emitted from uranium. Further, he noticed that a sheet of paper could block alpha rays, while beta rays can go beyond paper but not thin metal plates. Due to the varying characteristics of these two radiation rays, they were named alpha and beta rays. In 1903, another radiation ray with stronger radiolucency was discovered and named a gamma ray.

Rutherford proposed that electrons traveling around the nucleus consist of protons and neutrons, and for his accomplishment, he is known as "the father of atomic physics."


The Japanese version of the manuscript was originally published in Fukushima Minyu, a local newspaper in Fukushima prefecture, Japan, 1st and 8th July 2018 was reproduced for MRIC Global under the author's permission.

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