Uses and dangers of radiation Flashcards
what is irradiation
the process of exposing an object to a source of radiation
what is irradiation used in
- to preserve fruit and destroy any bacteria on it
- to sterilise surgical equipment
both using gamma rays
how are gamma rays used to kill cancer cells
the beams are aimed at the tumour from many different directions to maximise the dose on the tumour but to minimise the dose in healthy soft tissue, enough to kill the tumour, but so that healthy tissue isnt damaged
what needs to be considered when using radioactive sources in medical applications
the nature of decay (whether its alpha beta or gamma)
- toxicity
- half life
advantages of irradiation
- sterilisation can be done without high temperatures
- it can be used to kill bacteria on things that would melt
disadvantages of irradiation
- it may not kill all bacteria on an object
- it can be very harmful, could expose people’s cells to damage and mutation
what is radioactive contamination
when unwanted radioactive isotopes end up on other materials
when is contamination used
- used as tracers
why is medical contamination used
- the isotopes used have very short half lives, meaning after a couple of days there will hardly be any radioactive material in the persons body
- the isotopes are not poisonous
advantages of radioactive contamination
- radioactive isotopes can be used as medical and industrial tracers
- using isotopes with shorter half lives means exposure will be limited
- imaging processes can replace some invasive surgical procedures
disadvantages of radioactive contamination
- radioactive isotopes may not go where they are wanted
- it can be difficult to ensure that the contamination is fully removed so small amounts of radioactive material may be left behind
- exposure to radioactive materials may potentially damage healthy cells
- hazardous as radioactive atoms emit ionising radiation
what is the difference between irradiation and contamination
irradiation
- is when the object is exposed to a radiation source outside the object
- doesnt cause the object to become radioactive
- can be blocked with shielding
- stops as soon as the source is removed
HOWEVER
contamination
- is when the radioactive source is on or in the object
- the object will stay radioactive as long as the source is on or in it
- once an object is contaminated, the radiation cannot be blocked
- can be very difficult to remove contamination
how can we mange the risks of radiation
- wear protective clothing to prevent the body from becoming contaminated
- avoid contact with bare skin, and dont taste the sources
- wear face masks to avoid breathing in materials
- limit exposure time, so less time is spent around radioactive material
- handle radioactive with tongs
- keep material shielded when not in use
- wear gloves
- wear lead aprons
- use a radiation monitor
what is background radiation
low level nuclear radiation that is present in natural and man made sources
why is it better to have a sample with a longer half life than short
- because when the radioactive sample halves, a radioactive particle is emitted, meaning that there is a higher chance of irradiation. If it halves more frequently, that increases the chance of exposure to radioactive material
what is nucleur fission
the splitting of a large nucleus into 2 smaller nuclei and kore nutrons
what are the steps of nuclear fission
- the unranium nucleus absorbs a neutron and the nucleus splits into two daughter nuclei
- The nucleus also emits two or three more neutrons and gamma rays
- energy is also released - the neutrons can now be absorbed by more unstable nuclei
what are chain reactions controlled in
a nuclear reactor
what is nuclear fusion
the joining of two light nuclei to form a heavier nucleus, mass is converted into energy and released as radiation when this happens
when sterilising an object with radiation, how do we stop bacteria from getting in
by placing a plastic wrapper around it
how to sterilise an object with radiation
- place it in a plastic wrapper
- place the object near a radioactive isotope that emits gamma radiation
- this must be inside a lead shield, to protect workers from radiation
- withdrawing the lead shield allows gamma radiation to irradiate the object, and the gamma radiation kills any bacteria present
why doesnt the object become radioactive when irradiated
because the object only comes in contact with the radiation, not the radioactive isotope itself
effects of each type of radiation on the body
alpha : strongly ionising but easily stopped by dead cells on the skins surface. can be dangerous if inhaled or swallowed
beta : quite ionising, but can penetrate skin and damage cells
gamma : least ionising, can pass straight into the body and out
why is peer review important
so that findings can be checked and to prevent false claims
natural sources of radiation
- rocks
- cosmic rays - high energy particles which crash into the earths atmosphere
man made sources of radiation
- nuclear weapon testing
- accidents at nuclear power station
what can your exposure to radiation be affected by
- your location
- your occupation
how is nuclear radiation used in medicine
- exploring internal organs
- controlling or destroying unwanted tissue
how to check the function of a thyroid gland
- patient drinks radioactive iodine
- it emits gamma radiation which passes out of the body and can be detected
- if the scan shows that the thyroid has absorbed to much or too little iodine then the doctors can use this to diagnose
what are tracers used for
- finding tumours
- they emit gamma rays
What are some issues with the radiation in medicine?
- The tracer emit radiation that can pass out of the body and be detected, like beta or gamma
- the tracer should not be strongly ionising to minimise damage to body tissue
- The tracer must not decay into another radioactive isotope
- It must have a short half life, so that it’s not present in the body for a long period
What is radiotherapy?
Using ionising radiation to destroy certain cancers
How does radiotherapy work?
The machine contains a source of gamma radiation.
Gamma rays pass into the body and destroy the tumour.
problems with radiotherapy
- healthy tissue may be damaged as the radiation passes through the body
What are the benefits of using radiation inside the body?
The radiation is treated very precisely to the tumour, so there is less damage to healthy tissue
what are explosions in a nuclear weapon caused by
uncontrolled fission chain reaction
what is a controlled chain reaction used for
used in a nuclear reactor
