It will help the 1st year medical student to understand isotope with their advantage and disadvantage. Also, help to know about the different type and basic structure of isotope.
2. Definition
Atoms with same atomic
number/number of proton but
different atomic weight (number
of protons+neutrons).
So atoms may be different atomic
weight due to different neutron
number.
3. Isotopes are variants of a
particular chemical element which
differ in neutron number. All
isotopes of a given element have
the same number of protons but
different numbers of neutrons in
each atom.
4. The term isotope is formed from
the Greek roots isos ("equal") and
topos ("place"), meaning "the
same place“. So the meaning
behind the name is that different
isotopes of a single element
occupy the same position on
the periodic table.
7. The number of protons within
the atom's nucleus is
called atomic number and is equal
to the number of electrons in the
neutral (non-ionized) atom. Each
atomic number identifies a
specific element, but not the
isotope; an atom of a given
element may have a wide range in
its number of neutrons.
8. The number of (both protons and
neutrons) in the nucleus is the
atom's mass number, and each
isotope of a given element has a
different mass number.
9. Types of isotope
Stable isotope/ non radioactive
Unstable isotope/ radioactive
isotope
10. Stable isotope
The first evidence for multiple
isotopes of a stable (non-
radioactive) element was found
by J. J. Thomsonin 1913 as part of
his exploration into the
composition of canal rays
(positive ions)
11. Stability of an isotope depends on
the definite neutron to proton ratio
which is specific for a specific
atom.
In low atomic weight atoms
stability achieved with neutron to
proton ratio around one
12. In case high molecular weight
stability usually achieved by more
neutron than proton and the ratio
more than one (>1).
Naturally occurring isotopes are
predominantly stable isotope.
14. Unstable isotope (raidoactive)
The existence of isotopes was
first suggested in 1913 by
the radiochemist Frederick Soddy
based on studies of
radioactive decay chains that
indicated about 40 different
species referred to
as radioelements (i.e. radioactive
elements) between uranium and
lead
15. Unstable isotope (raidoactive)
Have the capacity to emit
radiation
These isotopes neutron and
proton ratio far from stability ratio
Isotopes of heavy elements are
usually unstable example: radium,
urenium
Aim of radioactivity is to become
stable
18. Radioactive decay
It is the spontaneous
decomposition or disintegration of
an unstable isotope of a definite
element in an attempt to become
a stable isotope with
simultaneous emission of
radiation (α,β,γ) and formation of
new element.
19. Radioactivity
It is the spontaneous emission of
accelerated particles (radiation)
from an unstable isotope by radio
active decay.
20. Mechanisms of radio active decay
Alpha decay: heavy atoms (atomic
number >70) may emit alpha
particles from radio active
nucleus.
beta decay: atomic number <60
may emit beta particles.
Positive beta decay: in case of
artificial isotope positive beta
particles (positron) emit.
21. Half life of radioactive isotope
Radioactive isotope Half life
14Carbon 5760 yrs
3Hydrogen 12 yrs
60Cobalt 5.3yrs
51Chromium 28days
32Phosphrus 14days
131Iodine 8days
99Technetium 8hrs
It is the time required for a radioactive
isotope to reduce its radioactivity half of
its initial value
22. Clinical use/importance of radio-
active isotope
Diagnostic use- to diagnosis
diseases
Therapeutic use- radiotherapy
treatment for malignancy
Use in tracer technique- to study of
metabolic pathway
Measurement of volume & spaces-
ECF volume, blood volume
Measurement of regional blood flow
Sterilization of medical instrument
23. Diagnostic use
Iodine uptake test for thyroid
disorder
Radio immune assay for hormonal
disorder
Organ scanning- bone, brain, thyroid
Absorption test- iron, Vit B12
RBC half life measurement
Isotope renogram for measurement
of GFR, renal clearance
24. Radiation hazards/disadvantage of
radio isotope
Immediate hazard:
1. Bone marrow depression and
immune suppression
2. Damage to intestinal mucosa
causing diarrhoea & malabsorption
3. Baldness, rough scaly skin
4. In pregnancy: fetal growth
retardation, congenital
malformation fetal or neonatal
death
25. Delayed hazards: carcinogenesis,
sterility, neonatal death
Genetic effect: DNA damage,
mutation
26. Radiosensitive tissue
These are most rapidly dividing
tissue. Such as
Bone marrow
Gonads
Lymph node
Skin
Intestine
Editor's Notes
It is the time required for a radioactive isotope to reduce its radioactivity half of its initial value