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gcse science P4 - E
specific for ocr gateway additonal science B.
Question | Answer |
---|---|
what is an unstable atom? | when there aren't an equal amount of protons and electrons |
what are the 3 different types of radiation? | alpha beta gamma |
where are these 3 types of radiation emitted from? | the nucleus of an unstable atom |
why is alpha radiation no use for diagnosis or therapy? | it is absorbed by the skin |
what is alpha radiation used for? | smoke detectors |
why is beta radiation's medical applications limited? | passes through the skin, but not bone |
what is beta radiation used for? | to treat the eyes to monitor the thickness of paper |
why is gamma radiation used in medicine? | it is very penetrating |
what is gamma radiation used for? | to treat cancers |
which gamma-emitting radioactive material is used to treat cancer? | cobalt-60 |
when is ionisation caused? | when nuclear radiation passes through a material |
what does ionisation radiation do to the body? | damages living cells increases the risk of cancer |
what is radiotherapy? | exposing cancer cells with large amounts of radiation to destroy the cells |
what is a similarity between x-rays and gamma rays? | they have similar wavelengths |
what is a difference between x-rays and gamma rays? | they are produced differently |
how are x-rays made? | by firing high-speed electrons at metal targets |
how can you control the rate of production and energy of x-rays? | using an x-ray machine |
can you change the gamma radiation emitted from a radioactive source? | no |
how are gamma rays made? | when the nucleus of an atom of a radioactive substance decays, any surplus energy is lost by emitting gamma rays |
what is a radioactive tracer used for? | to investigate inside a patient's body without surgery |
what is a commonly used tracer? | technetium-99m |
what kind of radiation does technetium-99m emit | only gamma radiation |
what other tracer also emits gamma radiation? | iodine-123 |
what is the tracer iodine-123 used for? | to investigate the thyroid gland |
how is a radioactive tracer used | -mixed with food and drink or injected into the body |
what is the progress through the body monitored by? | a detector such as a gamma camera which is connected to a computer |
what is a radioisotope used for? | to destroy a tumour |
what is the 1st technique of treating cancer? | -3 sources of gamma radiation are arranged around the patient with the tumour at the centre |
how does this decrease the damage to healthy tissue? | the three sources of radiation each account for one third, meaning the healthy tissue only receives one-third of the dose |
what is the 2nd technique of treating cancer? | -each radiation source is slowly rotated around the patient |
how does this decrease the damage to healthy tissue? | the tumour receives constant radiation but healthy tissue receives only intermittent doses |