Hello everyone and welcome to this week's blog post. In this article, I will be exploring the various uses of radiation and radioactive isotopes in medicine, including X-rays, CT scans, nuclear imaging and radiotherapy.
The discovery of radiation dates back to around 1895 when Wilhelm Röntgen was able to use electromagnetic radiation to create images of structures inside the body. Wilhelm Röntgen, who was Professor of Physics in Worzburg, Bavaria, was researching the path electrical rays took when they passed through an induction coil in a tube with a partial vacuum. When he covered the tube in black cardboard and darkened the room, he discovered that this apparatus caused fluorescent material to be displayed on a screen.
After further experimentation, during which Röntgen changed the thickness of paper around the tube and light levels of the room, Röntgen realised that while visible light was unable to pass through the black cardboard, these rays he had created could. As such, X-rays were discovered. Further, when his wife placed her hand between the cathode ray tube and the photographic plate, he was able to create an image which showed the bones inside her hand and her wedding ring.
This discovery proved incredibly useful during the following decades and its principles are still used very commonly today. This is partly because, when Röntgen published his discoveries about X-rays in 1895, he didn't protect them with a patent. This meant that anyone could utilise and build upon his work without paying him royalties.
As a result, the very next year, X-ray technology became used in several hospitals across the UK, including London Royal Hospital and the Glasgow Royal Infirmary. Indeed, in 1896, the head of the radiology department at the Glasgow Royal Infirmary was able to produce X-ray images of kidney stones and a penny stuck in the throat of a child, to name a few. In 1896, Dr Hall-Edwards was able to make the first diagnosis using X-rays (the X-rays showed him the precise position of a needle which was stuck in a woman's hand).
While Röntgen was the first person to discover X-rays, radioactivity was actually discovered by Henri Becquerel in 1896, when he was studying the work of Röntgen. The term radioactivity was then coined by Marie Curie in 1898. The work of these individuals, along with Pierre Curie, was instrumental in expanding knowledge of radiation. In addition, they also made substantial contributions to the use of radioactivity in medicine and surgery.
For example, in 1910, Marie Curie led research into using radioactivity to destroy tumours - researchers first placed radium close to the tumours, before eventually placing the substance into the tumour itself. While these exact methods are no longer used, Curie's use of radium marked the beginning of the use of radiotherapy in cancer treatment.
Additionally, during the First World War, Curie made further advances in the uses of X-rays in medicine. During the war, she funded the creation of 'les petites Curies', which were modified vans that operated as ambulances on the front lines. These ambulances had mobile X-ray units which could be transported to injured soldiers and used to check for internal injuries. Curie then went on to train frontline medical workers in how to use this equipment, which likely resulted in many lives being saved.
Imaging of the human body has progressed greatly since the development of X-ray technology in 1895. Today, X-ray technology has become much better, with images being much clearer. In addition, X-rays now require a dose of radiation 1,500 times lower than in 1895, which drastically decreases the risks for the patient.
Additionally, the development of advanced computers has allowed us to produce much more accurate, 3D images of the body. For examples, CT scans are now commonly used. These scans involve the patient moving through the CT scanner while an X-ray takes 2D, cross-sectional images of the body. These images are then put together by the computer to create a 3D image of the body. As such, CT scans are incredibly useful in diagnosing bone fractures, finding internal bleeding and monitoring the spread of tumours.
Radioactive tracers can also be used in nuclear medicine imaging to improve the quality of images. This is where radioactive substances are either injected into a vein or given by mouth. These substances then concentrate in different parts on the body, depending on the type of substance. For example, some of these tracers are modified to accumulate in tumours. These tracers then emit gamma radiation, which passes through the body and can be detected by computers to produce an image. These tracers have very specific properties - in addition to being modified to accumulate in a specific part of the body, they must also produce gamma (or sometimes beta) radiation so that they can pass through the body, they must be non-toxic, and they have a short half-life.
Radiation is also used in the treatment of cancer. According to the NHS, radiotherapy is used in cancer treatment in four different ways. The first (called curative radiotherapy), which is where radiotherapy is used to cure cancer completely. The second (called neo-adjuvant radiotherapy) is where radiotherapy is used to increase the effectiveness of other treatments, such as chemotherapy and surgery. Additionally, adjuvant radiotherapy can also be performed, which is where it is used to reduce the chance of cancer reoccurrence following surgery. Finally, in patients whose cancer has progressed to a stage where it is no longer curable, palliative radiotherapy can be performed to relieve symptoms and improve quality of life.
There are several different forms of radiotherapy. According to the American Cancer Society, radiotherapy involves using high-energy particles (such as X-rays, gamma rays, protons or electron beams) to damage and destroy cancer cells. Radiotherapy works as cancerous cells divide much faster than healthy cells. As radiation damages DNA, it prevents cancer cells from growing and kills them. Meanwhile, as the healthy cells do not divide as frequently, they are much less affected by radiotherapy and usually recover after treatment.
One of the most common forms of radiotherapy is external radiotherapy, where a machine is used to produce beams of radiation which are targeted at the tumour. Radiotherapy can also be performed by implanting radioactive metals inside the body around the tumours or by radiotherapy injections. This is where the patient is asked to swallow a radioactive liquid (either by swallowing a capsule or drinking the liquid directly). Alternatively, the liquid can also be injected into the blood.
Moreover, there are many other uses of radiation in medicine, including sterilising medical equipment, determining the volume of blood and diagnosing and treating abnormal thyroid function.
Nevertheless, while radiation has many uses in medicine, it can also be incredibly harmful to the human body. Indeed, it is now known that Marie Curie actually died from radiation poisoning.
Ionising radiation can cause damage to tissues in multiple ways. For example, the energy provided by radiation can split apart the water molecules found in cells. When these molecules reform, hydrogen peroxide can be formed, which is toxic to cells. Ionising radiation can also cancer as it can cause mutations in DNA. These mutations, called oncogenes, then stimulate the cell to divide uncontrollably by mitosis and form a tumour.
When someone is exposed to a large dose of ionising radiation over a short period of time, they may develop acute radiation poisoning. Symptoms of radiation poisoning include nausea, vomiting, diarrhoea, fever, hair loss and internal bleeding. In severe cases, acute radiation poisoning can be fatal. The symptoms experienced by the sufferer generally depend on how much radiation they were exposed to and which regions of the body were exposed. As the gastrointestinal system and bone marrow are highly sensitive to radiation, if they are exposed, then much less radiation has to be absorbed by the body for symptoms to occur.
The radiation produced by a single X-ray scan is not enough to cause significant damage to human tissues. However, repeated exposures could be deadly. For this reason, doctors, dentists and other medical professionals often wear lead aprons or leave the room while X-rays are being taken, so that they are protected from the risks of radiation.
Sources: