P4G
X - rays and Gamma rays
X-rays and gamma rays are used in medicine. They are electromagnetic waves and part of the electromagnetic spectrum.
X-rays and gamma rays have some other features in common. They:
Are ionising
Have similar wavelengths
However, they are produced in different ways.
Both x-rays and gamma rays are used in medicine for:
diagnosis (finding out what is wrong)
therapy (treatment)
they are both very penetrating and can pass into the body to treat internal organs.
However nuclear a
Radiation and x-rays can be damaging to living cells so great care must be taken to limit exposure to such radiation when it is used for diagnosis or therapy
How x-rays are produced
X-rays are manufactured by an x-ray machine. A hot cathode emits electrons that are attracted to a tungsten anode.
When the fast-moving electrons hit the metal target, most of their kinetic energy is transferred to heat but some is transferred to x-rays.
This machine allows the energy and intensity of the x-rays to be controlled. Gamma rays, on the other hand, are given out by radioactive materials. This process is totally random and so cannot be controlled as easily as x-rays.
Medical radioisotope
Materials do not become radioactive if they absorb electromagnetic radiation such as x-rays and gamma rays. However, they can become radioactive if they absorb particles such as neutrons. This is put to good use in manufacturing medical radioisotopes.
Materials are put into a nuclear reactor where they are revealed, forming the desired radioisotope.
For example, technetium-99 is widely used in medical imaging. It is generated from molybdenum-99, which is produced when molybdenum-98 absorbs neutrons.
Uses of radiation in medicine
Nuclear radiation is used in medicine to sterilise equipment, to help in diagnosis and to treat cancer with gamma rays
Sterilising equipment
Gamma rays are high energy electromagnetic waves which are only stopped by thick lead. This means they can easily pass through medical equipment, such as syringes.
As gamma rays pass through the packaging they will inactivate viruses and kill bacteria. As long as the equipment remains in a sealed plastic pack it will remain sterile.
Tracers
Radioactive tracers are used to investigate a patient's body without the need for surgery.
Gamma emitters and sometimes beta emitters are used. This is because gamma rays and beta particles can pass through skin, whereas alpha particles cannot.
Radiation from the radiostope used as a tracer is emitted inside the body. The radiation can penetrate tissues and leave the body to be detected.
Nuclear radiation can damage cells. To avoid possible harm to the patient, it is important that medical tracers do not stay active in the body for long periods,
Radioisotopes with short half-lives are chosen to make sure that the tracer does not stay radioactive in the body for long periods,
The radioisotope may be chemically attached to different substances, depending on the test being carried out..
The radioactive tracer is put into the body by one of the following ways:
By an injection
By ingestion (eating a solid with the tracer in it or drinking a liquid with the tracer in it)
The tracer is given enough time to move around the body before a radiographer positions a radiation detector outside the body. This produces a picture showing where the tracer has accumulated
Gamma rays damage cells whether they are normal or cancerous, so gamma rays must be focused on the tumour.
One way of doing this is to use a wide beam of gamma rays, but to rotate the beam around the patient, keeping the tumour at the centre. T
his concentrates the gamma rays on the cells that need to be killed