Transcript Four Primary Types of Ionizing Radiation: Alpha Particles

Four Primary Types of Ionizing
Radiation:
Alpha Particles
Alpha Particles: 2 neutrons and 2 protons
They travel short distances, have large mass
Only a hazard when inhaled
Four Primary Types of Ionizing
Radiation:
Beta Particles
Beta Particles: Electrons or positrons having small mass and
variable energy. Electrons form when a neutron transforms into a
proton and an electron or:
Four Primary Types of Ionizing
Radiation:
Gamma Rays
Gamma Rays (or photons): Result when the nucleus releases
Energy, usually after an alpha, beta or positron transition
Four Primary Types of Ionizing
Radiation:
X-Rays
X-Rays: Occur whenever an inner shell orbital electron is removed
and rearrangement of the atomic electrons results with the release of
the elements characteristic X-Ray energy
Four Primary Types of Ionizing
Radiation:
Neutrons
Neutrons: Have the same mass as protons but are uncharged
They behave like bowling balls
Four Primary Types of Ionizing
Radiation

Alpha particles
 Beta particles
 Gamma rays (or photons)
 X-Rays (or photons)
 Neutrons
RADIATION
FUNDAMENTALS
ATOMIC AND NUCLEAR
STRUCTURE
Bureau of Radiation Control
Radioactivity: Elements &
Atoms

Atoms are composed of smaller particles
referred to as:
– Protons
– Neutrons
– Electrons
Ionization

Ionizing radiation is produced by unstable
atoms. Unstable atoms differ from stable
atoms because they have an excess of
energy or mass or both.
 Unstable atoms are said to be radioactive. In
order to reach stability, these atoms give off,
or emit, the excess energy or mass. These
emissions are called radiation.
Types or Products of Ionizing
Radiation

neutron

or X-ray
Radioactive Atom
Ionizing Radiation
alpha particle
X-ray
beta particle
gamma ray
Radioactive Atom
Ionizing Radiation
alpha particle
X-ray
beta particle
gamma ray
Direct Ionization Caused By:

Protons

Alpha Particles

Beta Particles

Positron Particles
Indirect Ionization Caused By:

Neutrons

Gamma Rays

X-Rays
DNA and Radiation
Ionizing Radiation at the
Cellular Level

Causes breaks in
one or both DNA
strands or;

Causes Free Radical
formation
Commonly Transported
Radioisotopes

Americium-241= Diagnose thyroid
disorders, smoke detectors.
 Cesium-137= Cancer treatment.
 Iodine-125,131= Diagnosis & treatment
liver, kidney,heart, lung and brain.
 Technetium-99m=Bone and brain imaging;
thyroid and liver studies; localization of
brain tumors.
Radiation Measurement

Terminology:
– Exposure rate = amount radiation possible to
receive per unit time.
– Dose = total amount of radiation received.
Radiation and Radioactivity:
Units and Quantities
Department of Health
Bureau of Radiation Control
Introduction

Quantities (mass, volume, time, etc.) vs.
Units (grams, gallons, hours)
 Units of exposure, radioactivity, and energy
associated with ionizing radioactivity
 As hours and minutes are to time ...
Objectives

Define
– ROENTGEN, RAD, REM, CURIE, GRAY,
SIEVERT, BECQUEREL.
– SI units vs. Standard English units

Discuss the use and conversion of unit
prefixes
 Transform units using “unit analysis”
Background

Early risk associated with use of ionizing
radiation
 skin erythema dose - 25yrs
 1928 - ROENTGEN introduced by ICRP
Roentgen
Roentgen
Named after Wilhelm C. Roentgen
(thus the abbr... is capital “R”)
 Pronounced rent’gen with a hard “g”
 Limitations

– only applies to photons
– only applies in air
– only applies to energies less than 3 MeV
rad
rad

1 rad = 1 Roentgen
rem
rem


Roentgen Equivalent Man
The unit of dose equivalent for any type of
ionizing radiation absorbed by body tissue
in terms of estimated biological effect - Unit
of dose equivalent
 Dose in health record is in units of rem
 1 rem = 1 Roentgen
Quality Factor (Q)
The specific value that accounts for the
ability of different types of ionizing
radiation to cause varying degrees of
biological damage
– X-rays, gamma rays, & beta particles
– Neutrons & High energy protons
– Alpha Particles
1
10
20
Curie (Ci)

Named in honor of Pierre Curie

Radiation hazard does not solely depend on
the activity. It also depends on the type of
decay (alpha, beta, photon, etc.)
SI Radiation Protection Units
 Becquerel
(Bq) for Curie
– 1 Ci = 3.7 x 1010 Bq
 Gray (Gy) for rad
– 1 Gy = 100 rad
 Sievert (Sv) for rem
– 1 Sv = 100 rem
Unit Analysis
BASE UNIT CONVERSION TABLE
Unit
1 Bq
1 Ci
1 Bq
1 dis/sec
1 Ci
Unit Conversion
2.7 x 10-11 Ci
3.7 x 1010 Bq
1 dis/sec
2.7 x 10-11 Ci
3.7 x 1010 dis/sec
Unit Analysis (Con’t.)
BASE UNIT CONVERSION TABLE
Unit
Unit Conversion
1 rem
1 Sv
1 rad
1 Gy
1R
1 meter
0.01 Sv
100 rem
0.01 Gy
100 rad
2.58 x 10-4 C/kg
3.28 ft (39.37in)
Summary

Radiation Protection unit definitions
(including SI units)
 Unit Prefixes
 Unit conversions
Old Terms

Roentgen-Based on the quantity of electrical charges
produced in air by X or Gamma photons 1R=2 billion pr

RAD-Radiation Absorbed Dose is the work energy
resulting from the absorption of one ROENTGEN or 6.24
E5 Mev
More Old Terms

REM- Roentgen Equivalent Mammal is equal to the
absorbed does in RADS multiplied by a quality factor

Quality Factors
 Beta = 1
 Gamma & X ray photons = 1
 Alpha = 10
 Neutrons = 20
New Terms sort of
International Units have replaced the RAD
and REM
GRAY (Gy) = 100 RAD
SIEVERT (Sv) = 100 REM
Same Quality Factors apply to the Sv
Units of Radioactivity

Curie (Ci) = 2.22 E12 dpm or 3.7E10 dps
 Becquerel (Bq) = 1 dps
 Maximum Dose/year = 5 REM or 50 mSv
 Maximum Dose/year for Declared Pregnant
Woman & Minors= 0.5 REM or 5 mSv
Half Life Calculation
Annual Dose Limits
External/Internal Exposure Limits for Occupationally Exposed Individuals
Adult ($18 yrs)
Minor (< 18 yrs)
Whole body*
5000 mrem/yr
500 mrem/yr
Lens of eye
15000 mrem/yr
1500 mrem/yr
Extremities
50000 mrem/yr
5000 mrem/yr
Skin
50000 mrem/yr
5000 mrem/yr
Organ
50000 mrem/yr
5000 mrem/yr
Dose Response Relationships

0-150 rem—No or minimal symptoms
 150-400 rem—Moderate to severe illness
 400-800 rem—Severe illness deaths start
above 500 rem
 Above 800 rem—Fatal
***Acute whole body doses
Your Annual Exposure
Activity
Smoking
Typical Dose
280 millirem/year
Radioactive materials use
in a UM lab
<10 millirem/year
Dental x-ray
Chest x-ray
Drinking water
Cross country round trip by
air
Coal Burning power plant
10 millirem per xray
8 millirem per xray
5 millirem/year
5 millirem per trip
0.165
millirem/year
Estimated Exposure To The
National Population
Between
320 – 360 mr/yr
Another Look at Sources
Some Exposure Limits







2 mr/hr Dose rate to public / Federal
500 mr Emergency responder limit / State/BRC
5 r/yr
Occupational /Federal
5 r/hr
Turn back value / State/BRC
10 r
Property / Federal
25 r
Life saving / Federal
>25r
Volunteers only / Federal
Ref - 10CFR PART 20, EPA 400, FL-SOP
Security

All Radioactive Materials must be secured
or under direct supervision at all times
 There MUST be someone in the room at all
times OR the door must be locked.
Spill Response

On Skin—flush completely
 On Clothing—remove
 If Injury—administer first aid
 Radioactive Gas Release—vacate area,
shut off fans, post warning
 Monitor all persons and define the area of
contamination
ALARA
As Low As Reasonably Achievable—means making every reasonable
effort to maintain exposures to radiation as far below the dose limits as
is practicable consistent with the purpose for which the licensed
activity is undertaken, taking into account the state of technology, the
economics of improvements in relation to the state of technology, the
economics of improvements in relation to benefits to the public health
and safety, and other societal and socioeconomic considerations, and
in relation to utilization of nuclear energy and licensed materials in the
public interest.
Radiation Protection

Decrease Time

Increase Distance

Increase Shielding