The development of scanning techniques in the 20th century
Medical knowledge improved considerably during the 20th century. One of the foundational developments was the discovery of the X-ray by Wilhelm R枚ntgen in 1895. He was experimenting with cathode rays and realised that they could pass through flesh but not through bone.
Within six months, hospitals were installing X-ray machines. They had a major impact on medicine, as doctors for the first time could see inside the human body without having to operate. However, the early X-ray machines produced high doses of radiationEnergy carried by particles from a radioactive substance, or spreading out from a source. which led to serious side effects such as: damage to the skin and eyes; and cancer.
During World War One, X-rays saved thousands of lives as surgeons were able to operate more accurately. Since then, X-rays have been used routinely in hospitals to investigate problems with bones.
Breakthroughs since World War Two
All of the following scanning techniques have revolutionised medical knowledge, particularly over the past 30 years. They are non-invasiveA medical procedure that does not involve cutting the skin. but they enable doctors to identify diseases earlier and so improve people鈥檚 chances of survival.
| Scanning technique | Description |
| Ultrasound scan | This uses high-frequency sound waves to see inside the body, so it avoids the need to use radiation as in X-rays. It produces 3D images of internal organs like the heart and kidneys, as well as muscles. Since the 1970s, it has also been used to check the progress of foetuses in the womb. |
| MRI scan | Magnetic resonance imaging uses radio waves to build up a detailed picture of organs and tissues. It is used to detect areas of disease. MRI scanning machines can be used to detect tumours and other problems. |
| PET scan | Positron emission tomography uses a special dye containing radioactive tracers. The dye is injected into a vein. As the organs and tissues absorb the tracers, they are highlighted under a PET scanner, which allows doctors to investigate conditions such as cancer and heart disease. |
| CT scan | Computed tomography is an X-ray procedure that combines many X-ray images with the aid of a computer. The computer generates cross-sectional images of the internal organs and structures of the body. |
| Scanning technique | Ultrasound scan |
|---|---|
| Description | This uses high-frequency sound waves to see inside the body, so it avoids the need to use radiation as in X-rays. It produces 3D images of internal organs like the heart and kidneys, as well as muscles. Since the 1970s, it has also been used to check the progress of foetuses in the womb. |
| Scanning technique | MRI scan |
|---|---|
| Description | Magnetic resonance imaging uses radio waves to build up a detailed picture of organs and tissues. It is used to detect areas of disease. MRI scanning machines can be used to detect tumours and other problems. |
| Scanning technique | PET scan |
|---|---|
| Description | Positron emission tomography uses a special dye containing radioactive tracers. The dye is injected into a vein. As the organs and tissues absorb the tracers, they are highlighted under a PET scanner, which allows doctors to investigate conditions such as cancer and heart disease. |
| Scanning technique | CT scan |
|---|---|
| Description | Computed tomography is an X-ray procedure that combines many X-ray images with the aid of a computer. The computer generates cross-sectional images of the internal organs and structures of the body. |