One of the most important tools of modern medicine, the radiation Today, it offers powerful resources for both the diagnosis and treatment of diseases. Few know, however, that the discovery of the technique resulted in losses to human lives initially, and required a good dose of serendipity, or chance, to happen.
The controlled use of radiation in medicine involves the application of the principles of radioactivity, a process that occurs naturally in the unstable nucleus of some atoms. And it all started when the German physicist Wilhelm Conrad Röntgen publicized, in 1895, the existence of X ray which, it is important to remember, have nothing to do with radioactivity.
What Röntgen was actually investigating was the effect of passing electric current through vacuum tubes, when he noticed a strange fluorescent glow on a screen covered with barium platinocyanide, although the tube was wrapped in black cardboard. He realized that it was a radiation capable of penetrating opaque objects, calling it “X” (unknown).
Without knowing that X-rays were produced only by an external stimulus, the French physicist Henri Becquerel began researching that luminescence (emission of light after absorbing energy) in some materials in nature. To test his hypothesis, he placed uranium salts on a photographic plate wrapped in black paper, and exposed them to sunlight for several hours. The sign went dark.
The discovery of radioactivity
Still celebrating the supposed proof of his thesis that uranium absorbed the Sun’s energy and then “emitted it as X-rays”, the physicist tried to repeat the experiment days later. But as the weather was cloudy in Paris, he stored the uranium samples on photographic plates in a dark place.
When he returned later, Becquerel observed that, even without being exposed to sunlight, the plates were sensitized. Intrigued, the physicist repeated the experiment several times, varying the conditions and materials, and realized that some type of radiation passed through the black paper and veiled the photographic emulsion.
According to researcher Fabio Luiz Navarro Marques, manager of the Nuclear Medicine Center at the USP Faculty of Medicine, the “cosmos” would once again conspire “so that scientists Marie Curie and Pierre Curie get married and work together at the Sorbonne University in Paris. Using equipment developed by Pierre, Marie was able to identify the pitchblende [uranita]a mineral that contained uranium and other metals more radioactive than purified uranium itself.”
Of this process, the chemist explains to CNN, Marie Curie discovered two substances much more active than uranium. Naming them polonium and radiummathematics also coined the term for the first time “radioactivity”.
For her discoveries, Marie Curie not only became the first woman to win the Nobel Prize, in Physics in 1903 (along with her husband Pierre, and Becquerel), but she was also the first person in the world to win the prize twice, receiving also Chemistry in 2011.
Marie Curie and the dangers of radiation
When she died in 1934 of medullary aplasia, a rare condition that prevents the production of blood cells by the bone marrow, Marie Curie was completely unaware of the malignant effects of ionizing radiation. Accustomed to carrying test tubes with radioactive isotopes in her pocket, her precious notes, and even her recipe book, are to this day stored in shielded lead boxes to prevent radiation from escaping.
One of the most notable cases regarding the risks of ionizing radiation occurred in the 1920s, in the USA: there were the so-called “radium girls”, young people who painted watch faces with radium (to glow in the dark). Even with suspicions of the risks posed by radioactive materials, the company’s management did not take any type of precaution.
Using the “lip-pointing” technique, the girls wet the brushes with their lips to obtain a finer tip, which led them to ingest radium. This exposure generated serious health problems for these workers, as radioactive poisoning led to bone necrosis, severe anemia and cancer.
The public repercussion of the scandal caused stricter safety regulations were introduced into workplaces and encouraged the creation of legal instruments to hold companies accountable for the health and safety of their workers.
Paradoxically, the Manhattan Projectwhich developed the atomic bombs that killed between 150,000 and 245,000 people (in addition to exposing 600,000 “hibakusha”, or people affected by the explosion, to long-term radiation), was the first major initiative to develop protective measures against radiation, benefiting scientists, engineers and the 10 thousand “calutron girls” who, unknowingly, separated uranium-235 from U-238.
The benefits of radiation for the modern world
129 years after Röntgen’s initial “eureka”, we can safely say that the use of radiation has had a profound and transformative impact on life on Earth. Today, radioisotopes are used in a wide variety of processes, says Marques, the main one being the production of electrical energy in nuclear plants.
However, highlights the FMUSP chemist, the other important area of application “is in nuclear medicine, where radioisotopes are linked to molecules, forming radiopharmaceuticals, for diagnosing neurodegenerative, myocardial and oncological diseases. In the latter case, they can be used to treat tumors.”
Furthermore, the expert states that radioactive sources are also used in other sectors, such as mineralogy, agriculture, in addition to the use of so-called ionizing radiation in foods, to destroy pathogenic microorganisms and increase the shelf life of fruits and vegetables. In pest control, the Sterile Insect Technique (TIE) irradiates male insects, making them infertile.
Regarding the risk of radiation diagnostics becoming outdated, with the use of new technologies, such as nanoparticles and AI, Marques is categorical: “not at all, as all these topics are transversal to radiation”. He cites the case of nanoparticles that, when modified with radioisotopes, increase their diagnostic or therapeutic potential. As for AI, he sees it as an auxiliary tool.
Finally, speaking about serendipity, Marques highlights “that chance happens in any area of science, and only brains capable of interpreting it and having the tenacity to seek an answer will make this chance transform into processes that benefit humanity. ”, he concludes.
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