Radio isotope

GOVT. HOLKAR SCIENCE COLLEGE
INDORE , MP
TOPIC- Radioisotopes
SESSION 2015-16
SUBMITTED BY
Aman kakne
M.sc
SUBMITTED TO
PHARMA DEPT.

Basic properties
stability
production
Instruments
application of radio isotopes
RADIO ISOTOPE

What is radio isotope?
What is radio activity?
What are isotopes?
Alpha rays
Beta rays
Gamma rays
BASICPROPERTY

A radioactive form of an element,
consisting of atoms with unstable
nuclei, which undergo radioactive
decay to stable forms ,
,emitting characteristic alpha, beta,
or gamma radiation.
WHAT IS RADIOISOTOPE

The elements are termed as radioactive
because they are unstable undergo
spontaneous decomposition accompanied
by emission of radiations or rays.
Or
process by which atoms emit energetic
particles or rays
WHAT IS RADIOACTIVITY

Nuclides having the same no. of protons but
different no. of neutrons are termed as isotopes.
WHAT ARE ISOTOPES
Lilithium
3 No. of protons determines an
element’s identity
As atoms get bigger and heavier , the nuclide will get bigger and
heavier , protons thus will need ‘nuclear glue’ to hold them
together, neutron provides this glue, and prevents the positive
charge of proton to repel each other by a force called ‘’ strong
nuclear force’’ . Elements exhibits different no. of neutron and they
are called isotope of same element.

atomic symbol
atomic number
number of protons
mass number
number of
protons and
neutrons
B
11
5
NUCLEAR SYMBOLS

B11
5
9.1NaturalRadioactivity
WRITING NUCLEAR SYMBOLS
This defines an isotope of boron
In nuclear chemistry, often called a
nuclide
This is not the only isotope of boron
boron-10 also exists
How many protons and neutrons does
boron-10 have?
5 protons, 5 neutrons

1) Alpha rays carry two positive charge.
2) Alpha particles are similar to helium nuclei because of the same no. of mass
which is 4 amu
3) Are the alpha particles haves the same energy.
4) They have the least penetrating power among other and thus is not useful in
biological application.
5) When a radioactive element emits alpha particles from the nucleus of the atom
the resulting nucleus will have two positive charge less than the original nucleus
and thus it will correspond with element having its atomic no. less than two units,
and the mass no. of the nucleus will be less than 4 amu as compared to original.
This can be explained by decay of radium nucleus to yield random nucleus by
emission of alpha particles.
Ra
ALFARAYS
226
88
Rn
222
86
He
4
2
+

The are of two types
1) Eclectically positive particles which are called ‘positrons’.
2)Electrically negative particles which are called “negatrons”.
3)Have greater penetrating power than alpha rays.
4) They are usually accompanied by gamma rays.
5)Beta particles are able to pass through an aluminum foil or few millimeters.
6)They have low ionizing power than alpha particles.
7)The emission of beta particles do not alter the atomic mass but alters the
atomic number and is converted to element with higher atomic number for
e.g. :
C
BETA RAYS
6
14
N
7
14
Beta+


1)They are more penetrating than alpha and beta rays.
2)Same character as that of very short electromagnetic waves called
x-rays.
3ls)Gamma rays (g) - pure energy (electromagnetic radiation)
4)Highly energetic
5)The most penetrating form of radiation
6)They carry no charge.
7)as gamma rays are uncharged, they have poor ionizing power but
they can interact with molecules and atoms in specific media and can
produce ions and free radicals by dislodging electrons from orbitals.
GAMMA RAYS

HALF LIFE OF RADIOELEMENT
The decay of individual atom of a radioactive substance has been
found to be irregular. If a certain amount of radionuclide is taken and
the no. of disintegration per second is measured, it is found that,
after certain time, half of the original atoms would have got
disintegrated and only half of the original active atoms would be left
behind. The no. of disintegration per second will also now be half of
the original value. The decay time of radionuclide to half has been
constant irrespective of the quantity present. This time is termed as
half-life of the radionuclide.
half-life, t =0.693/
Polonium-212 =3 X 10 seconds
Iodine-131= 8 days
Phosphorous-32 = 14.3 days
Uranium-238= 4.5X 10
1/2 -7
4

Reactor irradiation
1) A reactor is having an arrangement of fissionable materials. Which slows
down the fast neutrons to thermal energies.
2) The fissionable material is take like uranium in the forms of rods and is
arranged in lattice pattern and hence the neutron flux is maximum in the
Centre where there is most uranium.
Co + n
4)A heavy-water moderator reactor using enriched (harwell reactor DIDO) is
having a max. flux 10 neutrons cm
PRODUCTION
27
59
Co
27
60
0
1
+
14 -2 s -1

While the reactors are able to produce a flux of neutron and gamma rays,
accelerating machines can use many other types of bombarding particles. They
have to be accelerated to high velocities so as to overcome the repulsive forces
of the nucleus.
The beam of energetic particles has been small and targets for irradiation have
to be put in this beam.
Mg + H Na + He
CYCLOTRON IRRADIATION
24 2 22 4
12 1 11 2

Ionization chamber
They are available in various shapes and sizes. An
ionization chamber consists of chamber filled with gas
and fitted with two electrodes kept at different electrical
potentials (50 to 100 volts for each centimeter of distance
b/w the two electrodes) and a measuring device to
indicate the flow of electrical current. Radiation brings
about ionization of gas molecules or ions which causes
emission of electrons which in turn revels the changes in
electrical current.
INSTRUMENTATION

1) Detects ionizing radiation.
2) Most popular radiation detectors, the do not need high-gain amplifier and
they can detect alpha- beta and gamma radiations.
3) Has largely been replaced by more sophisticated devices.
4) A G-M counter is having the ionizing gas and also having a quenching
vapour whose function have been
a) to prevent spurious pulses that may get produced due to the positive ions
reaching the cathode.
b) To absorb the photos emitted by exited by exited atoms and molecules
returning to their ground state.
Some quenching agents are chlorine, bromine, ethyl alcohol, ethyl formate as
organic quenching agent.
5) Ionized rays interact with chamber filled with gas, thus current produced
and reading is noted by radiation.
GEIGER-MULLERCOUNTERS

When radiation is incident on certain substances such as phosphor, a
flash of light is given out. It thus becomes possible to measure alpha,
beta, gamma radiations by scintillation detectors provided the detector
has been suitably modified for the type of radiation to be measured.
It gained popularity in the recent past. It has been mainly useful for
counting of gamma emitters.
Earlier it has been done visually. This method was obviously tedious,
slow and sensitive.
The instrument consist of a photomultiplier tube, consisting of
photoelectric cells directky linked to electron multipliers have given rise
to sensitive detection devices.
Fluorescent material or ‘phosphor’ have been also used.
SCINTILLATIONCOUNTER

1) Consist of a cell.
2) A photomultiplier tube which is covered with phosphor
or fluorescent material to convert scintillations into
electrical pulses, in amplifier.
3) Sodium iodide crystal is being used to increase the
degree of fluorescence
4) Gamma radiation will enter into the crystal. Where it
gives rise to a flash of light.
5) This is brought to the photo multiplier tube.
6) Photomultiplier tube converts flash amplifiers to
electrical impulse.

Liquid scintillation counter

In therapeutic use of radioisotopes, the radiations emitted
cause destructive effects on existing cells and disallow
the formation of new cells and tissues. Due to the reason
, the radioisotope therapy has been applicable to those
diseases condition in which extrinsic cellular metabolic
malfunction exists.
The selection of isotope has been found to depend upon the , type ,
energy and properties of the radiation required.
APPLICATIONSIF
RADIOISOTOPES

The therapeutic used radioisotopes have been found to
depend mainly on their ability to ionize atoms.
Measurement of radiations and resulting in ionization is
expressed in million of electrons volts called MeV.
The strength of alpha, beta, gamma is expressed as MeV.
Radioisotopes can be given internally or externally. If the
Radioisotope are use externally or used as implants in
sealed capsule in a tissue , the dose could be terminated
by removal of the source, the dose cannot be stopped by
removal of the source.
RADIOISOTOPESIN THERAPEUTICSDIAGNOSIS.

1)GOLD ( Au) finds use in the treatment of abdominal
and pleural effusion(excess fluid builds around the lung) .
Associated with malignant tumors. It is given the form of
colloidal gold suspension.
2) ( Au) treatment of carcinoma of uterus and urinary
bladder.
3)Colloidal gold ( Au) injection has been used for
diagnostically studying the blood circulation in liver.
4 ) ( Au) finds use in neoplastic suppressant. (skin
cancer)
USESOF ISOTOPES
198
198
198
198

5) Sodium phosphate ( P) used in therapy of polycethemia vary to decrease
the rate of formation of erythrocytes leukemia .
6)Cobalt labeled cynocobalamins (vitamin B12) find use in the diagnosis of
pernicious anemia.
7) The labeled isotopes of cobalt have been Cobalt-57, Cobalt-58, Cobalt-60.
8)Sodium iodide ( I) preparation finds use in the treatment of thyroid
disorders.
9)Sodium iodide ( I) used in diagnosing the thyroid gland.
10)Iodinated ( I) human serum albumin injection finds use to investigate
the cardiovascular functions.
11)Iiodippurate (I ) used to diagnose renal functions.
12)Sodium rose bengal (I ) injection finds use as a diagnostic agent to test
liver functions.
USESOF ISOTOPES
131
32
131
131
131
131

Excellent biological and medicinal studies
have been carried out with radioactive
isotopes as ‘tracers’. Modern knowledge of
many biochemical processes have been the
cause of such elaborated studies, C and H
are most commonly use radio-nuclides for
this purpose.
RESEARCH
16
14
3
1

By radioactive radiations sterilizing pharmaceuticals in their
pharmaceuticals in their final packed containers and surgical
instrument in hospitals. The radiation does not destroy or
harm most pharmaceuticals. No heat or chemicals gets
involved.
Thermo mobile ( easily affected by heat) substances such as
vitamins, hormones, antibiotics etc. can be sterilized.
Co or Cesium-137 may be used for sterilizing instruments.
This is done in bhabha atomic research Centre at Bombay.
STERILIZATION
30
27

Radio isotope

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