POST RN BScN SEMESTER II

1. RADIOACTIVITY
AND ITS USES
UNIT VIII
POST RN BSN
LIFE SAVING CON

2. Natural Radioactivity
• Radiation - the particles or rays emitted
• Radioactivity - process by which atoms
emit energetic particles or rays
– comes from the nucleus
• Nuclear symbols - what we use to
designate the nucleus
– Atomic symbol
– Atomic number
– Mass number

3. particle
Electromagnetic wave
Unstable nucleus
Atoms which emit electromagnetic radiation or
a particle by the spontaneous transformation of
their nucleus are called radioactive.

4. B11
5
atomic symbol
atomic number of
protons
mass number of
protons and
neutrons
Nuclear Symbols

5. Three Isotopes of Carbon
• Each nucleus contains the same number of
protons
• Only the number of neutrons is different
• With different numbers of neutrons the mass
of each isotope is different

6. Unstable Isotopes
• Some isotopes are stable
• The unstable isotopes are the ones that
produce radioactivity
• To write nuclear equations we need to be able
to write the symbols for the isotopes and the
following:
– alpha particles
– beta particles
– gamma rays

7. Types of radiation
• Beta Particle (β)
• Gamma Ray (γ)
-
• Alpha Particle (α)

8. Radioactive decay
Some atoms are radioactive this means
their nucleus is unstable and decays to
become more stable. When nuclei decay
they emit or get rid of something from the
nucleus

9. There are three types of radioactive decay
Alpha decay : This is when 2 protons and 2
neutrons leave the nucleus to help it become
stable
Alpha particle.
A positively charged particle that consists of
two protons and two neutrons bound together. It
is emitted by an atomic nucleus undergoing
radioactive decay and is identical to the nucleus
of a helium atom.

10. Beta Decay: This is when a neutron in
the nucleus turns into a proton and
electron. The electron then leaves the
nucleus.
Beta particles are high-energy, high-
speed electrons or positrons emitted
by certain types of radioactive nuclei
such as potassium-40. The beta
particles emitted are a form of
ionizing radiation also known as
beta rays.

11. Gamma decay, a high energy photon is emitted
from the nucleus to attain a lower energy
configuration. In the gamma decay of a
nucleus, the emitted photon and recoiling
nucleus each have a well-defined energy after
the decay.
Gamma rays are ionizing radiation, and are
thus biologically hazardous. They are classically
produced by the decay of atomic nuclei as they
transition from a high energy state to a lower
state known as gamma decay, but may also be
produced by other processes.

12. Medical Applications of
Radioactivity
• Modern medical care uses the
following:
– Radiation in the treatment of cancer
– Nuclear medicine - the use of
radioisotopes in the diagnosis of
medical conditions

13. • Based on the fact that high-energy
gamma rays cause damage to
biological molecules
• Tumor cells are more susceptible
than normal cells
• Example: cobalt-60
• Gamma radiation can cure cancer,
but can also cause cancer
Cancer Therapy Using Radiation

14. Nuclear Medicine
• The use of isotopes in diagnosis
• Tracers - small amounts of radioactive
substances used as probes to study internal
organs
• Nuclear imaging - medical techniques
involving tracers
• Example:
– Iodine concentrates in the thyroid gland
– Using radioactive 131
I and 125
I will allow the study
of how the thyroid gland is taking in iodine

15. Tracers
• Radioactive tracers can be used to see how well
organs in your body are working or to find areas of
disease.
e.g. radioisotopes of iodine or technetium.
• Often these are mixed with a drug that collects in a
particular organ in the body.
• If we then inject the drug into the body, then by
detecting the radiation, we can examine that
organ.

16. Preparing the Tracer

17. The tracer being injected into thhe
Patient

18. Gamma Camera
A gamma camera detects the radiation coming from the patient and
produces an image of where the radioactivity is in the body.

19. Obtaining the Image
• The gamma camera displays the
position of each gamma ray that it
detects.
• This is a bone scan made using
technetium-99.
• Can you see where the patient was
injected?

20. Tracers and their Uses
Bone : 99m
Tc used to detect cancer, stress fractures
and bone graft success.
Thyroid: 123
I used to access over-active and under-
active thyroids, as well as thyroid tumours,
cysts and goitres.
Lungs: 133
Xe inhaled for ventilation studies (airways)
and 99m
Tc administered for perfusion studies
(blood flow).
Heart: 201
Tl used to study muscle performance.
Brain: 99m
Tc used to assess dementia and stroke
damage.
Dilution analysis to access blood and water
volumes (the tracer mixes with certain body
fluids).
Body blood: 99m
Tc used to assess volume.
Red cells: 51
Cr is attached to these.
Minerals: 24
Na and 42
K used to monitor body sodium and
potassium.

21. Radiotherapy
• Rapidly dividing cells are particularly sensitive to damage by radiation.
For this reason, some cancerous growths can be controlled or
eliminated by irradiating the area containing the growth. External
irradiation can be carried out using a gamma beam from a radioactive
cobalt-60 source,
• Internal radiotherapy is administered by planting a small radiation
source, usually a gamma or beta emitter, in the target area. Iodine-131
is commonly used to treat thyroid cancer, probably the most successful
kind of cancer treatment. It is also used to treat non-malignant thyroid
disorders. Iridium-192 implants are used especially in the head and
breast. They are produced in wire form and are introduced through a
tube called a catheter to the target area. After administering the
correct dose, the implant wire is removed to shielded storage.
• Treating leukemia may involve a bone marrow transplant, in which case
the defective bone marrow will first be killed off with a massive (and
otherwise lethal) dose of radiation before being replaced with healthy
bone marrow from a donor.

22. Gamma Knife
This technique is
used for brain
surgery . Instead
of opening the
patient's head the
gamma rays from a
Cobalt 60 source
are focussed on
the tumour. The
location of the
tumour would have
been accurately
mapped earlier
using an MRI or CT
scan