5.
contd.
Examples of
specific uses of radioactive isotopes
emitting alpha, beta(+/-) or gamma radiation
The uses of radioactive isotopes
usually depends on their
penetrating power and the value of their half-life
Both specific industrial and medical
applications of nuclear radiation sources are described.
(See
detailed properties of alpha, beta and gamma radiation)
5b.
Uses of alpha particle sources
-
Because alpha particles are
easily stopped, an alpha source is used in some
smoke detectors.
- A sealed weak alpha source
of americium-241, with a long half-life of 458 years, it effectively produces a
constant signal in a detector - formed of two electrodes close together with a potential difference across
them.
- It does this by sending a stream of alpha particles to
the sensor across an air gap
which causes ionisation of air molecules, this allows an electrical current flow
of ions (charges) and hence a constant electrical
signal.
- The nuclear decay equation is:
-
americium-241 ===>
neptunium-237 + alpha particle
-
+
- For more examples see
nuclear equations
- Any smoke particles present will block and absorb some of the alpha particles and
change the sensor signal by reducing the amount of ionisation of air
molecules, and this drop in signal triggers the alarm.
- Beta and gamma radiation would be of no use because the smoke particles would not stop them, no change in signal, no alarm triggered!
- Note:
- Although gamma radiation is also emitted, smoke
particles have no effect on it.
- This type of smoke detector can be safely used in the house
because it is a very weak source using a tiny amount of the americium
radioisotope.
- An average smoke detector for domestic use contains about
0.29 micrograms of Am-241 (in the form of americium dioxide), and its activity
is around 37000 Bq (37000 disintegrations/second).
- It sounds a lot, but don't
worry about it, non of the alpha particles can get out of the detector chamber
and there are thousands of particles hitting or passing through your body every
second with no ill-effect!
- The alpha emitting americium-241 can be used to gauge and
control the thickness of very thin metal foil sheet production (see beta
radiation gauging for more details as to how this is done).
Alpha
sources are too readily absorbed to show up accurately with a Geiger counter or
other detector and so are not suitable for 'tracer' applications.
- However, an alpha particle emitting isotope of
radium (radium-223, half-life 11.4 days) can be directly injected
in tiny quantities into tumourous tissue to directly irradiate and kill
cancer cells.
-
radium-223 ===>
radon-219 + alpha particle
-
- Its a rare but excellent medical use of an alpha emitter.
- Since they
are not very penetrating, there is less chance of damaging healthy
cells surrounding the tumour.
- This is an example of internal
radionuclide therapy.
- See also
uses of beta
radiation in cancer therapy.
more on the properties of alpha particles
and
nuclear equations for alpha decay
TOP OF PAGE
and sub-index for this page
5c.
Uses of beta
minus radiation sources
Reminders about the use of radioisotopes and radiation
in medicine (medical physics)
A more detailed discussion is given near the top of the
page - a quick reminder of why radioisotopes are so useful in diagnosing and
treating medical conditions. Alpha emitting radioisotopes are usually too
dangerous and not sufficiently penetrating to be of use in medicine. However
despite the dangers, beta minus (electron emission), beta plus (positron
emission) and gamma emitting radioisotopes are widely used in diagnostic
medicine and treatments for dangerous medical conditions such as cancer.
-
Most Beta particles are stopped by a few mm or cm of solid materials.
-
Beta emitting radioisotopes can be used to monitor the
thickness (gauge) of a sheet of material
- i.e. used in continuous gauging
situation especially in fast moving production line situations.
- The thicker the layer the more beta radiation is absorbed,
so by measuring the beta radiation signal it can form the basis of an automatic
thickness control.
- A beta source is placed on one side of a sheet of material.
- A detector (e.g. a Geiger counter) is put on the other side and can monitor how much radiation gets through.
- The signal size depends on thickness of the sheet and it gets smaller as the sheet gets thicker.
- Therefore the signal can be used to monitor the sheet thickness.
- However, the radioisotope must give a stable and constant
emission to give create a stable constant signal from the detector.
- Therefore the half-life must be quite long so that any change in the signal
does not result from rapid decay but only from change in the thickness of
the sheet material passing through beta particle beam.
- You can't use gamma radiation because it is too
penetrating and unaffected by the sheet of material, and alpha radiation sources
are no good either, because alpha particles wouldn't even penetrate the material
sheet.
-
This idea is used to control production lines of paper, plastic or steel sheeting
(diagram below).
-
After the sheet material passes through 'flattening' rollers, it passes between a beta source and detector.
- The detector signal is checked against that for a preset thickness.
- The signal controls the position of the rollers producing
the sheet of material.
- If the signal is too big, the sheet is too thin, and the rollers are moved apart to thicken the sheet.
- If the signal is too small, the sheet is too thick, and the rollers are moved closer together.
- You can use gamma emitting radioisotopes to do the same
thing.
Radioactive tracers can be used to diagnose some
medical conditions.
- Radioisotopes can be injected into the human
body or taken in a tablet and then what happens to the this radioactive 'tracer'
isotope as it is moved around the person's body can be monitored from
outside with a suitable external detection system.
- A computer takes the multiple readings from scanning the
emissions and builds up an accurate picture of where the radioisotope has gone
in the body.
- The more concentrated the tracer the stronger the reading
so the system produces a image ('map') of where the tracer has gone and
where it may concentrate from the strongest radiation readings.
- The technique can be used to detect and diagnose medical
conditions including cancers and blood stream circulation problems.
- The radiation emitted must pass out of the body to reach
the detector, alpha sources can't be used, the radioisotope applied must be a
beta or gamma emitter.
- It is important that a low dose of the radioisotope is
used AND has a relatively short half-life of a few hours or a few days to
minimise the risk of cell damage from the emitted beta or gamma radiation.
- A short half-life means the radioactivity in the body
will rapidly disappear to almost zero.
- A computer can analyse the detector signals from either
beta of gamma radiation to build up on a screen a picture of e.g. blood
circulation in the body can be followed.
- Another example is the use of iodine-131 to check the
functioning of the thyroid gland. If the thyroid gland is functioning normally
its expected uptake of iodine can be 'raced' using this radioisotope - an
example of a diagnostic scan.
- Lack of a concentrated signal from the thyroid gland
would indicate it is malfunctioning and not processing iodine as it should.
Iodine-131 emits beta and gamma radiation and both radiations can pass out
of the body to a detector.
-
iodine-131 ===>
xenon-131 + beta minus particle
-
+
- I've read that iodine-123 is now used, which gives a more
pure and safer gamma emitting radioisotope.
- Iodine-131 has a half-life of ~8 days, so with a low
dosage used, after a few weeks all the radioactivity would disappear.
-
or
Alpha or beta emitters can be used to
treat tumours
- The technique of internal radiation therapy
involves placing (injecting or implanting) the radioisotope inside the body,
either into, or near, the tumour (cancer growth).
- Alpha emitters can be injected near the tumour.
Alpha radiation is highly ionising and will do great damage to nearby cancer
cells. Since alpha particles have a low penetration, they will do little damage
to healthy cells around the tumour.
- Beta emitters are used in implants which are
placed in or near the tumour. Beta particles are more penetrating and, unlike
the less penetrating alpha particles, will pass through the implant casing to
damage the adjacent cancer cells. However, using more penetrating beta emitters,
risks damaging healthy cells beyond the cancer cells of the tumour.
- The half-lives of radioactive sources used for internal
treatments, should have short half-lives to limit the time healthy cells are
exposed to radiation.
- Gamma emitters can be used in the technique of
external radiation therapy by aiming the highly penetrating gamma rays at
the tumour in the body. See
uses of gamma radiation
for more details.
more on the properties of beta particles and
nuclear equations for beta decay
TOP OF PAGE
and sub-index for this page
5d.
Uses of gamma radiation sources
(mention of using X-rays too)
Reminders about the use of radioisotopes and radiation
in medicine (medical physics)
A more general discussion is given near the top of the
page - a quick reminder of why radioisotopes are so useful in diagnosing and
treating medical conditions. Alpha emitting radioisotopes are usually too
dangerous and not sufficiently penetrating to be of use in medicine. However
despite the dangers, beta minus (electron emission), beta plus (positron
emission) and gamma emitting radioisotopes are widely used in diagnostic
medicine and treatments for dangerous medical conditions such as cancer.
-
Gamma radiation is highly penetrating and so gamma sources are used where the radiation must be detected after passing through an appreciable thickness of material.
- This is used in various
tracer situations
and usually the half-life should be relatively short to avoid any health hazards
if used in detecting and diagnosing medical conditions.
-
A gamma emitting tracer can be added to the
flow of water in a pipe and the outside of the pipes monitored with a Geiger counter.
- Any leaks would be detected by an increase in radiation reading
where the leak is.
- Tracer monitoring can be used in industry and out in the
general environment.
- The flow of water in underground
streams or pipes can be followed in a similar way.
Radiotherapy (radiation therapy)
- Gamma emitters can be used in the technique of external radiation therapy
by aiming the highly penetrating gamma rays at the tumour in the body.
- It does seem ironic that the very radiation which causes cancer, can also be used to treat it.
- Radiotherapists direct a beam of
gamma radiation is directed onto the
tumor site to kill the cancer cells, but it must be an appropriate dose to
minimise damage to healthy cell tissue surrounding the cancer tissue.
- High doses of radiation will kill living cells and the
idea is to focus a beam of radiation onto the cancer cells.
- Unfortunately the radiation passes through the
'good' tissue too and kills or damages 'good' cells and this damage can cause
sickness, but, if the cancer cells are all killed, surely its worth it.
- Modern techniques
use multiple gamma sources or a single rotating source that are focused on the tumor.
- You can use high powered X-rays in the
same way to destroy a tumour (see extra section below).
- The dose of radiation to destroy a tumour
is also big enough to harm healthy surrounding tissue - but this
technique minimises this.
- You can:
- (i) slowly rotate the radiation source
with the patient's tumour at the centre of the circle - the
tumour is subjected to the full radiation does, but much less so
for all the surrounding healthy tissue.
- (ii) use multiple sources (e.g. 3) of
radiation, all focussed on the tumour - it means the tumour
receives the full radiation dose, but the surrounding healthy
tissue only 1/3 of the dose.
- This means the surrounding 'good cells'
are less frequently irradiated and minimises potential harmful side-effects on the rest of the body (e.g.
sickness or other mutations).
- Precautions taken in radiotherapy to
protect both radiographers and patients.
- Radioactive sources are stored in
shielded conditions - lead is good dense barrier.
- Radiographers were protective clothing
and distance themselves behind barriers in a separate room.
- All medical staff involved wear
photographic film badges to monitor how much radiation they
absorbed.
- Patients, apart from being given the
minimum effective dose of radiation, should have the healthy
parts of the body protected in some way.
- Radiotherapy can avoid the need for intrusive
surgery which has its own risk factors.
- Radiotherapy is often used to shrink a
tumour making it easier to remove.
- The rest of the tumour can be then
surgically removed.
- Radiotherapy is the used again to ensure
the tumour cannot re-grow in the same location.
- The gamma emitters like cobalt-60 used should have relatively
long half-lives to give the instrument a good working life
without having to replace the radioactive sources too frequently.
- Lots of shielding is required in a specially designed
room to protect the radiographer, patients and medical staff from any radiation.
-
Unwanted side effects
from radiotherapy
- Patients subjected to cancer treatments
involving nuclear radiation will suffer from side effects.
- Its difficult to avoid damage to healthy
cells.
- Patients may suffer from reddening and
pain from a 'burning' effect (a bit like sunburn).
- Patients may experience tiredness and
vomiting.
- The immune system can be affected and
radiotherapy patients are at greater risk to infections.
- There is even a risk of causing other
cancers.
- You have to weigh up risk versus benefit,
harm versus good.
- You need an intelligent informed
discussion between clinicians and patients to make a decision of
what course of action to take to treat the cancer.
-
Brachytherapy
- Brachytherapy involves inserting a small
sealed radioactive source into the tumour itself - the
radioisotope used is often a beta emitter because gamma rays are
too penetrating and would be less absorbed by the tumour (alpha
emitters are too dangerous?).
- This directly hits the tumour with a high
dose of radiation, BUT, a much lower dose of radiation to the
surrounding tissue.
- Brachytherapy is used to treat prostate
gland cancer and cancers in the cervix and womb.
- It can also be used alongside external
radiotherapy.
- The half-life of the radioisotope needs
to be relatively short to minimise irradiation of healthy tissue
and it must not be able to enter the bloodstream to cause harm
elsewhere in the body.
-
X-rays
- X-rays are used in CAT scanning techniques
to produce cross-sectional images of sections of your body.
- CAT is the acronym for 'computerised axial
tomography', a procedure capable of creating 3D images of inside
your body.
- X-rays have the next most 'energetic' photons
after gamma rays, and are produce by X-ray machines rather than
radioisotope emissions.
- Both X-rays and gamma rays are both used to
diagnose medical conditions, examine internal organs and bones and
destroy cancer cells - the latter is called radiotherapy (described
in previous section).
- In radiotherapy, X-rays are often
preferred to gamma rays for several reasons:
- X-ray machines just produce the X-rays
when needed - radioisotopes emit continuously.
- You can control the rate of production of
X-rays - gamma radiation intensity is fixed for a given
radioisotope source.
- You can control the photon energy of the
X-rays - use the minimum energy for effective treatment -
radioisotopes emit radiation of fixed energies.
Gamma
radiation can be used in a non-destructive way to test the structure of a
material.
- In a sense it is an alternative to X-ray
photography for more dense materials e.g.
- It is used test the structure and
quality of pipe welds e.g. in pipelines used in the oil industry.
- A gamma source is placed inside the
pipe and photographic paper wrapped around the weld.
- If there is any gap or flaw in the
weld, more gamma radiation gets through and shows up as increased
exposure on the 'gamma-ray picture'.
- Its better to find out the fault now,
rather than later when it fractures, and has to be 'dug up' or
retrieved from the bottom of the sea!
- Gamma rays are used to test for flaws in jet
engines in a similar way, any flaw allows more gamma rays to pass
through so any minute cracks will be detected. Analogy - this is a
similar technique to having an X-ray to detect fractures in bones or
examination of luggage for airport security.
Gamma
radiation can be used to measure the thickness of materials.
- This technique has already been described in uses of beta
radiation, where the signal from transmitted nuclear radiation gives a measure
of thickness, a technique described as gauging.
- It is used in the automobile industry to measure the
thickness of steel or aluminium in car body production
Because gamma radiation is so deadly and
penetrating it can be used to
sterilise surgical equipment or packaged
food.
- This irradiation is done with a strong gamma emitter like
cobalt-60, with a long half-life which
means the source can
last for many years with out replacement.
- The radiation is deadly for bacteria even
in the most microscopic pockets of apparently smooth and shiny stainless
steel of surgical instruments.
- A high does of gamma radiation will kill any
microbe-bacteria cells on surgical equipment.
- Gamma radiation will penetrate microscopic cracks or
pores in medical equipment that might harbour harmful bacteria.
- It has the advantage over old fashioned 'boiling
in water' of not requiring heating and even plastic instruments can be
sterilised at room temperature without any damage.
- It is very convenient for packaged 'convenience'
food!
- Again, a high does of gamma radiation will kill
bacteria and prevent the food decaying and shouldn't involve any
degradation.
- After air-tight packing and sealing, the food is quite safe to eat
on opening later (days-months), and is NOT
radioactive.
- After cooking and sealing
in a plastic packet, you don't need to reopen to complete the sterilization to give it a long shelf-life!
- Gamma radiation is used to sterilise male insects as a
method of pest control.
- Gamma radiation is used to sterilise blood for
transfusion.
- Radiation pellets of gamma emitters are used in grain
elevators to kill insects and rodents in the same way radiation prolongs the
shelf-life of foods by destroying bacteria, viruses, and moulds.
Using
gamma emitter tracers in medicine
- By injecting a radioactive tracer into a patients body
(or swallowing a drink/tablet), its movement in the blood stream around the body
can be monitored with an external detector system.
- This enables clinicians to detect and diagnose certain
medical conditions.
- The radioisotope used must be a beta or gamma radiation
emitter to penetrate the body and be externally detected.
- The radioisotope must have a short half-life for safety
reasons.
The gamma emitting radioisotope sodium-24,
can be used in tracer studies of animal blood circulation, an important
diagnostic tool in clinical medicine.
- It undergoes beta decay with a half-life of 15 hours, a
safe time for medical use.
-
sodium-24 ===>
magnesium-24 + beta minus particle
-
+
- The emitted beta or gamma radiation can be detected
outside of the body.
- The tracer can be injected into the body in a sodium
chloride (saline) solution.
Technetium-99 is a gamma emitter (half-life 6 hours) and
is used in medicine as a tracer.
- In medical applications, in a suitable chemical form,
the radioisotope is injected into the body and its 'movement' can be followed
by a suitable external detector system.
- Time is allowed for the radioactive tracer to spread and its progress
tracked with a detector outside the body.
- The patient can be placed next to a 'detection screen' that shows where the radioactive tracer is.
- The effective function of organs like the liver and digestion system can be checked.
- The half-life must be relatively short
so it does not linger in the body increasing the harmful effects of cell
damage.
- Technetium atoms can be incorporated
into many organic chemicals called radiopharmaceuticals which can be
used to monitor biochemical aspects of the bodies chemistry e.g. the
functioning and performance of a particular organ.
Similarly, a patient can breathe in air with a gaseous gamma emitter in it, and the effectiveness and structure of the lungs can be checked.
- The detector system can be focussed on rib cage and lung
area of the body once the gaseous radioactive compound has been breathed in.
- The gas must be a molecule containing a suitable
radioactive atom.
Iodine-123,
a gamma emitter (123I, half-life 13 hours), is used to check on the
functioning of a thyroid gland.
- Thyroxine is an important hormone that
controls how much energy your body uses (the metabolic rate).
Thyroxine is also involved in digestion, how your heart and muscles
work, brain development and bone health. When the thyroid gland
doesn't make enough thyroxine (called hypothyroidism), many of the
body's functions slow down - tiredness - lack of energy, is one
symptom.
- The body needs iodine to make the hormone
thyroxine and so the take up of iodine can be monitored by measuring the gamma
radiation from the thyroid gland.
- Here you are matching a gamma emitting
isotope that matches an important element in a gland or organ.
- The patient is given a tablet containing an
iodide salt of the radioactive iodine (e.g. potassium iodide K123I).
- The thyroid gland absorbs some of the iodine
and uses it the same way as non-radioactive iodine.
- (Reminder: Isotopes of an element are
electronically, and therefore chemically, identical.)
- What happens to the iodine in the thyroid
gland is measured outside the body with a gamma camera - you can
tell whether the thyroid gland is functioning properly - if not,
diagnose the cause and effect appropriate medical treatment - which
might just involve taking thyroxine tablets - but thyroid cancer is
a much more serious matter.
- For clinical diagnosis iodine-123 is better
than iodine-131 because it does not emit beta radiation -
potentially more harmful and it also has a shorter half-life,
reducing possible harmful side effects.
- Note that in this situation, gamma radiation, being the most penetrating,
passes out through the body and so readily detected outside the body by
some suitable detector e.g. with a special camera or fluorescent screen.
- The half-life should be long enough to
allow good detection BUT NOT too long to be dangerous to the
body over a period of time!
- Short half-lives minimise the risk of damaging
healthy cells by reducing the amount of radioactivity circulating in
the body.
-
One method of treating thyroid cancer is
to inject Iodine-131 into the body in a soluble salt form e.g.
a potassium
iodide (K131I)
tablet or solution injection, so that it deliberately concentrates in the thyroid gland and
the gamma and beta radiation kills the thyroid cancer cells.
- Iodine-131 (131I, half-life = 8
days)
- This is another example of 'medical
physics' and important diagnostic technique in clinical medicine.
-
Beta
sources can be used, though not as penetrating as gamma and have an
increased risk of cell damage..
-
Alpha
sources are too readily absorbed to show up via a detector and so are not suitable for these 'tracer' applications.
- However, an alpha particle emitting isotope of
radium can be directly injected in tiny quantities into tumourous tissue
to directly irradiate and kill cancer cells (see
uses of alpha radiation).
- See also
uses of beta radiation in
cancer therapy.
more on the properties of gamma radiation and
nuclear origin of gamma radiation
TOP OF PAGE
and sub-index for this page
5e.
Uses of positron radiation sources
(beta plus decay nuclides)
and
use in PET scans
One of the most important uses of beta plus
(positron) emitters is PET Scanning in medicine.
PET is the acronym for
Positron Emission
Tomography and uses radioactive isotopes that emit positrons in the
beta plus mode of decay.
PET scanning is a technique used to show the
effective functioning, or otherwise ('malfunctioning') of various tissues
and organs enabling diagnosis of certain medical conditions.
Introduction to PET scans:
Positron emission tomography
(PET) scans are used in medicine to produce highly detailed three-dimensional
images of the inside of the human body. PET images can clearly show the part of
the body being investigated, including any abnormal areas, and can highlight how
well certain functions of the body are working. PET scans are often combined
with computerised tomography (CT) scans to produce even more detailed 3D images,
known as a PET-CT scan. PET scans may also occasionally be combined with a
magnetic resonance imaging (MRI) scan, known as a PET-MRI scan.
Why are PET scans are used?
An important advantage of a
PET scan over other diagnostic techniques is that it can show how well certain
parts of your body are working, rather that showing what a particular part of
the body looks like. PET scans are particularly helpful for investigating
confirmed cases of cancer, to determine how far the cancer has spread and how
well it's responding to treatment i.e. keep track of the behaviour of a tumour.
Sometimes PET scans of blood vessel function are used to help plan operations,
such as a coronary artery bypass graft of the heart or brain surgery for
epilepsy. They can also help diagnose some conditions that affect the normal
workings of the brain, such as dementia.
How do PET scans work?
PET scanners work by detecting the
gamma radiation given off by a substance called a radiotracer as it collects in
different parts of your body. In most PET scans a radiotracer called
fluorodeoxyglucose (FDG) is used, which is similar to the naturally occurring
sugar glucose, so your body treats it in a similar way in its energy releasing metabolic
chemistry. By analysing the areas where the radiotracer does and doesn't build
up (varying concentration), it's possible to work out how well certain body
functions are working and identify any abnormalities. For example, a
concentration of FDG in the body's tissues can help identify cancerous cells
because cancer cells use glucose at a much faster rate than normal cells because
of an increase in rate of cell division.
-
How is the procedure carried out?
- The patient is injected into a vein of the arm or
hand with a substance that is
normally present and used in the body e.g. a special compound like glucose
with a positron emitting isotope of fluorine in it (e.g. fluorodeoxyglucose, FDG).
- Remember that glucose is an important molecule in the
bodies metabolism, so monitoring its concentration is a way of monitoring
metabolic activity.
- The radioisotope must have a short half-life (19F
110 min, < 2 hours) to minimise radiation exposure to the patient and the molecule carrying
the radioisotope then spreads around the body of the patient into tissues
and organs over the next hour and acts as
a tracer.
- The explanation outlined below applies to any
positron emitter used in PET scanning.
- The fluorine-19 decays by positron emission (beta+
disintegration)
-
189F ===>
188O +
0+1e
-
What can you find out from a PET scan?
- The distribution of the radiated gamma rays from the
radioactivity will match up with the bodies metabolic activity i.e. some of
the bodies biochemistry which involves the energy releasing glucose.
- Therefore the cells which are working hardest e.g.
dividing cancer cells, using
more of radioisotope 'labelled' molecule, will
give out more gamma radiation and will show up as a more intense area are on
the scan.
- Therefore PET scanning is used to diagnose some types
of cancer.
- PET scans can also show areas of damaged tissue in the
heart by detecting decreased blood flow, so is a diagnostic method for
coronary artery heart disease. Dead or damaged heart muscle can cause a
heart attack.
- PET scans can plot blood flow and activity in the
brain which can help diagnose conditions like epilepsy.
- Active cancer tumours can be detected by PET scanning
showing the relative metabolic activity in tissue, which is greater in
cancer cells because they are growing more rapidly than healthy cells, so
you get a stronger signal from the cancer cells.
-
See section 7.
How
positron emitting radioisotopes are made in a cyclotron
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Atomic structure, radioactivity and
nuclear physics revision notes index
Atomic structure, history, definitions,
examples and explanations including isotopes
1. Atomic
structure and fundamental particle knowledge needed to understand radioactivity
2.
What
is Radioactivity? Why does it happen? Three types of atomic-nuclear-ionising radiation
3.
Detection of
radioactivity, its measurement
and radiation dose units,
ionising
radiation sources
- radioactive materials, background radiation
4.
Alpha, beta & gamma radiation - properties of 3 types of radioactive
nuclear emission & symbols
,dangers of radioactive emissions - health and safety issues and ionising radiation
5.
Uses of radioactive isotopes emitting alpha, beta (+/–) or gamma radiation in
industry and medicine
6. The half-life of a radioisotope - how
long does material remain radioactive? implications!, uses of decay data and half-life values
-
archaeological radiocarbon dating, dating ancient rocks
7. What
actually happens to the nucleus in alpha and beta radioactive decay and why? nuclear
equations!, the
production of radioisotopes - artificial sources of radioactive-isotopes,
cyclotron
8.
Nuclear
fusion reactions and the formation of 'heavy elements' by bombardment techniques
9.
Nuclear Fission Reactions, nuclear power
as an energy resource
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