Ionizing Radiation and Its Interactions with Matter
Radiation Interactions
with
Matter
Types of Interaction
with Matter
•
Direct
interaction:
particulate
radiation
(
α
, and
β
particles)
are
directly ionizing
and
disrupt
the
atomic
structure
of absorbing
matter.
•
Indirect
interaction:
electromagnetic
r
adiation
(
X
,
and
γ
rays)
are indirectly ionizing
because they do not produce
biological damage themselves but
produce secondary electrons
(charged particles) after energy
absorption in the matter
.
Ionizing radiation may be divided into directly and indirectly ionizing:
Alpha (α) particles
•
Positively
charged
•
Higher
mass
particles (2P
+ 2
N)
•
Lower
velocity
•
Highly
ionizing
•
Quickly losing their
energy
•
Weakly
penetrate in
body
tissue
•
Stopped
and
fully
absorbed
by
low
density
material
with
a
thickness
of
few
millimeters such
as
paper,
and
clothes.
Beta (β) particles
•
Lower
mass
with
a
single
negative
charge
•
Less
energetic
•
Higher
velocity
than alpha
particles
•
Penetrate
tissues to
a greater
depth
(skin)
•
Stoppe
d
b
y
p
l
a
s
t
i
c
materi
a
l
(
fe
w
c
e
ntimeter
s)
or metal ma
t
erial
(f
e
w
millimeters).
Neutrons
•
Uncharged
(neutral)
•
More
penetrated than charged
particles
•
Produce
ionizing
of
matter
indirectly via secondary
events.
•
Travel
great
distances in
air (100s
to even
1000s meters), and
several
meters
in solid
matters
•
Stopped only with hydrogen
rich
shielding such
as
concrete
or
water.
Electromagnetic radiation (X, and γ rays)
•
Gamma ray originate from
nucleus
•
X-ray originate from electron
cloud
of
atom.
•
Both
are photons
(massless
&
uncharged)
•
Progress at
the speed
of
light
•
Deeply penetrate further than alpha &
beta
•
Stopped by dense metal,
concrete,
or
earth.
•
Indirectly
ionizing
They are indirectly ionizing because they do not produce chemical and biological
damage themselves but produce secondary electron after absorption their energy by
matter
.
Sources of Radiation
A.
Natural
Sources
1.
Cosmic
radiation
2.
Terrestrial
radiation
3.
Internal
Source
B. Man
-
made
Sources
1.
Public
exposure
2.
Occupational
exposure
Natural Source: Cosmic radiation
•
Charged particles
from
the
sun
and
stars
interact with
the
earth’s
atmosphere and magnetic field
to produce
a
shower
of
cosmic radiation consists
of
positively charged particles
,
as well as
gamma
radiation
.
•
The exposure of
an
individual to cosmic
rays
is
greater at
higher elevations than
at
sea
level because at
higher
elevations
the
amount of
atmosphere shielding
decreases
and
thus
the
dose of
cosmic
rays
increases.
•
Ground,
rocks,
building materials
and
drinking
water
contained
many
radioactive
materials such as
radium
,
uranium
and
thorium
which
are ingested with
food and
water.
•
Radon
gas
is
originated
from
the
decay
of
natural
uranium
in
soil,
and
when
it is inhaled by human
emits
alpha
radiation
that cause
lung
cancer
.
•
The
dose from
terrestrial sources also
varies in
different
parts of
the
world
according
to
the
concentrations
of
uranium and
thorium in their
soil.
Natural
Source:
Terrestrial
radiation
•
We
have
various radioactive
isotopes
inside
our bodies
from
birth such
as:
1.
P
otassium-40
2.
T
r
i
t
i
u
m
(
3
H
)
3.
C
arbon-14
4.
L
ead-210
•
The variation in
dose from
one person to another is
not as
great
as
the
variation in
dose from
cosmic
and
terrestrial
sources.
Natural Source:
Internal
radiation
Man
-
made Source:
1-
Public
exposure
The majority of people
may
exposed to radiation for one or several
times during their
life
from
the
following
sources:
a)
Medical X-ray for diagnosis
(chest
X-ray)
b)
Nuclear medicine for therapy
(iodine
-131,
Technetium
- 99,
Cobalt-60, and
Cesium-137)
c)
Consumer
products
(tobacco,
fuels
(gas,
coal), ophthalmic glass,
televisions, airport X-ray systems,
smoke
detectors, building &
road construction materials,
etc.).
d)
Residual fallout
from nuclear weapons testing, shipment, and
accidents.
•
Some
workers
are
exposed to artificial sources
of
radiation
commonly
used
in
the
manufacturing
and
service industries such
as:
1.
Nuclear
fuel
cycle
at a nuclear
plant
2.
X-ray
machines
3.
Radiography
Man
-
made Source:
Occupational
exposure
The
average
annual radiation
dose
from:
•
Natural sources
(
Radon, Internal,
Terrestrial, Cosmic
)
(
82
%)
•
Man-made
(
Medical
X-ray,
Nuclear Medicine, Consumer Products
)
(
18%
)
Types
of
Radiation
Units
&
Doses
Types
of
Radiation
Units
1.
Measurement
of Decay Rate
•
The
amount
of
radioactive
material
in
a given object contains unstable
atoms which are continuously decaying, so
the
more unstable atoms,
the
greater
the
decay rate.
This
rate
of
decay
is
measured by
two
units:
a)
Curie
(Ci)
is
a unit used
to
measure a radioactivity and related
to
the
decay
rate
(disintegration
rate),
so One curie =
2,200,000,000,000
disintegrations
per
minute
(2.2
x 10¹²
dpm).
This means that every
minute, 2.2 x
10¹²
atoms decay and give off
radiation.
b)
Becquerel (Bq)
is
a unit also used
to
measure a radioactivity
and
one
Becquerel
is that
quantity
of
a radioactive material
that
will
have
60
dpm. As a result, there are 3.7 x 10¹º Bq
in
one
curie.
2.
Measurement
of Exposure
Dose
Roentgen (R)
measure
of
how
many ion pairs are formed
in
a given volume
of air
when
it is exposed
to
radiation only
to
gamma and
x-rays.
3.
Measurement
of
Absorbed
Dose
a)
Rad
(
R
adiation
a
bsorbed
d
ose)
measure
energy absorbed from any type
of
radiation, but
it
does not describe biological effects
of
different
radiations.
b)
Gray
(Gy)
is
a
standard
international
(SI)
unit
also
used
to
measure
absorbed
dose, and each
1
Gray
= 100
rads
.
Types
of
Radiation
Units
4.
Measurement
of
Equivalent
Dose
It
is
the
quantity of radiation dose
that is
relative
to
the
harm
or
risk
caused by
a given
dose of radiation when
compared
to
any
other
doses of
radiation
of any
type.
Equivalent
dose
=
absorbed dose
x
quality factor
(Q)
a)
R
oentgen
e
quivalent
m
an
(rem)
(1 rem =
1000
mrem).
b)
Si
e
v
e
rt
(
S
v
)
i
s
s
tandar
d
inter
n
ational
(
SI
)
unit
a
lso
us
e
d
t
o
measure
equivalent
dose,
and
each
1
Sievert
=
100
rem
.
Types
of
Radiation
Units
Dose:
The
amount of
radiation
you receive and measured by
(
mrem
).
Dose Rate
(
intensity):
how
fast you receive
the
dose and
measured
by
(
mrem
/
hr
).
Biological
effectiveness
of each
type
of
radiation
depend
on:
1.
Type
of
radiation
2.
Type
of
tissue
3.
Period
of
time
exposure
Types
of
Radiation
Doses
Types
of
Radiation
Doses
1.
Equivalent
dose
compare biological effectiveness
of
different types
of radiation
on the
same tissue
(absorbed dose
quality factor
of
radiation
type)
(rem or
Sievert).
2.
Effective
dose
estimate risk of
radiation in humans
(sum
of
equivalent doses
to
each
organ and tissue
factor)
(Sievert
-
Sv)
3.
Collective dose
is
dose received per person X
number
of persons
exposed
per
year.
4.
Chronic dose
is
a radiation dose received
over
a long period of
time.
5.
Acute
dose
is
a
radiation
dose received
over
a
short
period of
time.
THANK
YOU
Ionizing radiation interacts with matter in direct and indirect ways, leading to various effects on biological systems. Directly ionizing particles disrupt atomic structures, while indirectly ionizing radiation like electromagnetic waves produce secondary electrons. Alpha particles have high ionization abilities but weak penetration, beta particles penetrate deeper with less energy, and neutrons require hydrogen-rich shielding. Electromagnetic radiation, including gamma rays and X-rays, are massless and penetrate deeply, requiring dense shielding for containment.
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Presentation Transcript
Types of Interaction with Matter Ionizing radiation may be divided into directly and indirectly ionizing: Direct interaction: particulate radiation ( , and particles) are directly ionizing and disrupt the atomic structure of absorbing matter. Indirect interaction: electromagnetic radiation (X,and rays) are indirectly ionizing because they do not produce biological damage themselves but produce secondary electrons (charged particles) after energy absorption in the matter.
Alpha () particles Positively charged Higher mass particles (2P + 2 N) Lower velocity Highly ionizing Quickly losing their energy Weakly penetrate in body tissue Stopped and fully absorbed by low density material with a thickness of fewmillimeters such as paper, and clothes.
Beta () particles Lower mass with a single negative charge Less energetic Higher velocity than alpha particles Penetrate tissues to a greater depth (skin) Stoppedby plastic material(few centimeters) or metal material (few millimeters).
Neutrons Uncharged(neutral) More penetrated than charged particles Produce ionizing of matter indirectly via secondary events. Travel great distances in air (100s to even 1000s meters), and several meters in solid matters Stopped only with hydrogen rich shielding such as concrete or water.
Electromagnetic radiation (X, and rays) Gamma ray originate from nucleus X-ray originate from electron cloud of atom. Both are photons (massless & uncharged) Progress at the speed of light Deeply penetrate further than alpha & beta Stopped by dense metal, concrete, or earth. Indirectly ionizing They are indirectly ionizing because they do not produce chemical and biological damage themselves but produce secondary electron after absorption their energy by matter.
Sources of Radiation A. NaturalSources B. Man - madeSources 1.Public exposure 1.Cosmic radiation 2.Occupationalexposure 2.Terrestrial radiation 3.InternalSource
Natural Source: Cosmic radiation Charged particles from the sun and stars interact with the earth s atmosphere and magnetic field to produce a shower of cosmic radiation consists of positively charged particles, aswellasgamma radiation. The exposure of an individual to cosmic rays is greater at higher elevations than at sea level because at higher elevations the amount of atmosphere shielding decreases and thusthedoseof cosmicraysincreases.
Natural Source: Terrestrialradiation Ground, rocks, building materials and drinking water contained many radioactive materials such as radium, uranium and thorium which are ingested with food and water. Radon gas is originated from the decay of natural uranium in soil, and when it is inhaled by human emits alpha radiation that cause lung cancer. The dose from terrestrial sources also varies in different parts of the world according to the concentrations of uraniumandthoriumintheirsoil.
Natural Source: Internalradiation We have various radioactive isotopes inside our bodies from birth such as: 1.Potassium-40 2.Tritium (3H) 3.Carbon-14 4.Lead-210 The variation in dose from one person to another is not as great as the variation in dose from cosmic and terrestrial sources.
Man -made Source: 1- Publicexposure The majority of people may exposed to radiation for one or several times during their life from the following sources: a)Medical X-ray for diagnosis (chestX-ray) b)Nuclear medicine for therapy (iodine -131, Technetium - 99, Cobalt-60, andCesium-137) c)Consumer products (tobacco, fuels (gas, coal), ophthalmic glass, televisions, airport X-ray systems, smoke detectors, building & road construction materials, etc.). d)Residual fallout from nuclear weapons testing, shipment, and accidents.
Man -made Source: Occupational exposure Some workers are exposed to artificial sources of radiation commonly used in the manufacturing and service industries such as: 1.Nuclear fuel cycle at a nuclear plant 2.X-raymachines 3.Radiography
The average annual radiation dose from: Natural sources (Radon, Internal, Terrestrial, Cosmic) (82%) Man-made (Medical X-ray, Nuclear Medicine, Consumer Products)(18%)
Types of RadiationUnits 1. Measurement of Decay Rate The amount of radioactive material in a given object contains unstable atoms which are continuously decaying, so the more unstable atoms, the greater the decay rate. This rate of decay is measured by twounits: a)Curie (Ci) is a unit used to measure a radioactivity and related to the decay rate (disintegration rate), so One curie = 2,200,000,000,000 disintegrations per minute (2.2 x 10 dpm). This means that every minute, 2.2 x 10 atoms decay and give off radiation. b)Becquerel (Bq) is a unit also used to measure a radioactivity and one Becquerel is that quantity of a radioactive material that will have 60 dpm. As a result, there are 3.7 x 10 Bq in one curie.
Types of Radiation Units 2.Measurement of Exposure Dose Roentgen (R) measure of how many ion pairs are formed in a given volume of air when it is exposed to radiation only to gamma and x-rays. 3.Measurement of AbsorbedDose a) Rad (Radiation absorbed dose) measure energy absorbed from any type of radiation, but it does not describe biological effects of different radiations. b)Gray (Gy) is a standard international (SI) unit also used to measure absorbed dose, and each 1 Gray = 100 rads.
Types of Radiation Units 4. Measurement of EquivalentDose It is thequantity of radiation dose that is relative to the harm or risk caused by a given dose of radiation when compared to any otherdosesof radiation of any type. Equivalentdose= absorbeddosex qualityfactor (Q) a)Roentgen equivalent man (rem) (1 rem = 1000mrem). b) Sievert (Sv) is standard international (SI) unitalso usedto measure equivalent dose, and each 1 Sievert = 100rem.
Types of Radiation Doses Dose: The amount of radiation you receive and measured by (mrem). Dose Rate (intensity): how fast you receive the dose and measured by (mrem/hr). Biological effectiveness of each type of radiation depend on: 1.Type of radiation 2.Type of tissue 3.Period of time exposure
Types of Radiation Doses 1.Equivalent dose compare biological effectiveness of different types of radiation on the same tissue (absorbed dose quality factor of radiation type) (rem or Sievert). 2.Effective dose estimate risk of radiation in humans (sum of equivalent doses to each organ and tissue factor) (Sievert - Sv) 3.Collective dose is dose received per person X number of persons exposed peryear. 4.Chronic dose is a radiation dose received over a long period of time. 5.Acute dose is a radiation dose received over a short period of time.
