Transcript Nuclear medicine

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Radio activity is important in medicine
because it is used in diagnosing and
therapy.
Therapy is treatment such as treating
cancer. Tumours are destroyed by shooting
gamma rays at tumours. In this presentation
will not be talking about that. We will be
specializing in imaging. Radio activity is used
for tracing materials around the body. This
presentation is going to specialize in
diagnostic imaging . Diagnosing means
finding out the cause of the persons illness
or injury. The images are collected and
passed on to the doctor who carries out the
correct treatment.
•ADVANTAGES
AND
DISADVANTAGES
OF NUCLEAR
MEDICINE
•THE USES OF
NUCLEAR
MEDICINE
• PROCEDURE AND
RADIOACTIVE ISTOPES
USED IN NUCLEAR
MEDICINE
• HOW NUCLEAR MEDICINE
DETECTS DIFFERENT
ORGANS
How radio nuclides are
produced
Diagram of a nuclear
reactor:
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How radio nuclides are
produced
Most medical radio nuclides are prepared
by neutrons bombardment in a nuclear
reactor.
Iodine 131 (131I) is an example of a radio
nuclide that is produced in this way.
Tellurium 136 (136Te) is placed in a nuclear
reactor and under the intense
bombardment eventually captures a
neutron. The resulting nuclide then decays
to 131I by the emission of beta radiation as
the equation shows:
130 Te+1 n
131 I+0 β
52
0
53
1
Elution
Half life & elution of
radio nuclides
Saline solution is passed through the
column; the technetium which is being
produced by the beta decays because of the
molybdenum is soluble in saline but the
molybdenum itself is not. The process is
known as elution and results in a solution
of sodium pertechnetate,which is collected
in an output vial the content of the output
vial can be diluted and split in to a number
of patients doses the total amount of
radioactivity is goverened by the half life of
molybdenum. The generator is eluted daily
until the radiation activity concentration
falls to the level that is too low to be useful.
Which happens after 2 or 3 half lifes this
means that delivery of generator to the
hospital is necessary on weekly basis.
Technetium 99m
If the radio nuclide has a long half
life, the patient and others would
be subjected to a continuous
radiation dose. A short half life
such as the six hour half life of
technetium 99m, limits the
radiation dose but can give
problems of the time required to
transport the radio nuclide from
the production site to the hospital.
Procedure and radioactivity
isotopes.
•
Radioisotopes are substances which contain atomic
nuclei that emit alpha, beta and gamma radiation. If
any of these substances are taken into our body they
emit radiation giving us a method of locating where it
is. It acts like a beacon. The selected radioisotope is
attached to a convenient chemical compound that is
administered to the body. It then makes its way
through the system leaving a trail of radiation
permitting us to trace its path. It will concentrate the
activity in a particular organ of the body allowing
detail imaging of the structure. The reason that we can
detect the tracer outside the body is because the
radioactive tracer is relatively penetrating . The
gamma camera detects signals which then build up a
picture of the distributed radioisotope in the body.
Gamma emitters are only used.
How nuclear medicine detects problems
within different areas in our organ
• In order to investigate a body
organ. A suitable radioactive
tracer having a particular
affinity for that organ is
injected into the blood stream
this is up taken by the organ of
interest which is then assessed
by imaging with the gamma
camera. The image beside
explains how whole process
works.
Here are some example of organs detected
using specific tracers for specific organs
99mTc,45ca
123I,99Tc
99Tc
 Used to detect cancer stress
fracture and bone graft
success.
 Used to assess over active and
under active thyroids as well as
thyroid tumours, cysts and
goitres.
 Liver: Radio nuclides used are
used to investigate liver disease
and disorders of its blood supply.
Here are some example of organs detected
using specific tracers for specific organs
 Lungs: Radio nuclides used are
133Xe (xenon) and 99mTc
(technetium).
133Xe used for ventilation studies and
99mTc used to monitoring blood flow.
 Heart and circulation: Radio nuclides
used are 99mTc
(technetium) and
201 Tl (thallium). Investigates cardiac
output, blood volume and circulation,
blood clots and the functioning of the
heart muscles.
Here are some example of organs detected
using specific tracers for specific organs
 Brain: Radio nuclides used are
15
O (oxygen), 18 F(fluorine), 123I
(iodine) and 99mTc
(technetium). Measures brain
blood flow and functioning.
Investigates stroke damage, brain
receptors and response to drugs.
 Kidneys and bladder: Radio
nuclides used are 99mTc (
technetium). Investigates blood
and urine flow.
ADVANTAGES & DISADVANTAGES
 Can measure body composition
using dilution analysis.
Assesses body function
 Whole body scanning is
possible e.g. assessing diseases
and is particularly useful in
of the skeleton and detects
up taking tests and in
tumours when their site is
monitoring flow rate
known.
ADVANTAGES ARE:
It can identify skeletal
problems, like stress
fractures early due to
increased activity of bone
cells
 Monitors behaviour following
treatment especially drug
induced changes.
Advantages & Disadvantages
DISADVANTAGES ARE: • Disposal of radio activity
•Generally poor
waste, including that from
resolution compared
patients, require special
with other imaging
procedure.
modalities
• Relatively high costs
associated with radio
•Radiation risks due
tracer production and
to administered
administration.
radionuclide
•Can be invasive,
usually requiring an
injection into the
blood stream.
Safety and risk of Nuclear
Medicine
 Nuclear medicine is not safe for the
use of human beings, so therefore
should not be used on healthy
people.
 Also the procedure is not
recommended for pregnant women
because unborn babies have a
greater sensitivity to radiation than
children or adults.
 The main reason why radioactive
sources are used even though they
are dangerous is because the patient
is already under risk as they are ill, so
using the radioactive substances
would not put the patent under any
further danger but may find a cure
for the illness.
Radioactive substances are
emitted in to the body so the
safest way is to use a radio
nuclide which has a short half
life, so it can decay to a safe
level in the fastest possible time.
Also the radio nuclide can not
have a too short of a half life
because then it would not be
useful as it would be too weak
even before the images have
been taken.
Safety and risk of Nuclear
Medicine
Most of the administered
radioactive isotopes is excreted as
urine via the kidney and bladder
but same is excreted as
perspiration and saliva. This means
that the patient has radio active
substances on their skin and
should take extra care when
around other people. If accidents
like urination and vomiting happen,
it must be assumed until proven
otherwise, that the contamination
is radioactive.
Safety precautions to be taken
when near a patient has been
injected with radioactive
substance. Wear a pathology gown
and disposable gloves also
minimise the time spend with the
patient and maximise the distance
from the patient.