1

Safe Handling of Radiation andRadioisotopes(Basics)
Safe handling Ⅰ
Institute of Resource Development and Analysis,
Kumamoto University
Akihiro Kojima
2023

Human evolution and radiation
Since the beginning of time, all living things have been, and are still being, exposed to radiation.

Ancient times

Present day
Cosmic radiation

Cosmic radiation

Radiation from naturalradioactive materials
Naturalradiation

Naturalradiation

Radiation from naturalradioactive materials
Artificial
radiation2

Discovery of X-rays
1895

3

Dr. Röntgen discovered X-rays

Vacuum discharge experiment

Wilhelm C Röntgen（Germany）

X-ray photograph of a human hand taken by
Dr. Röntgen for the first time in the world

Started application to medicine

Discovery of radioisotopes and radioactivity

4

discovered that uranium
1896 Becquerel
ore emits radiation
Natural radiationand Marie Curie
1898 Pierre
discovered radioisotopes
They named polonium and radium.

Metal cross
A. H. Becquerel(France)radioactivity

1902 Rutherford presented “disintegration
theory of radioactivity”

alpha and beta rays,
emanating from radioactive
nucleus

Pierre & Marie Curie(France & Poland)

E. Rutherford(England)Use of radiation in various fields
Flow rate & velocity
exams
Reinforced plastics

Non-destructive
testing

5Industrials

Weld inspection

Thicknessmeasurement
Regulating
ripening

Gauging

Agriculture

Selectivebreeding

New drugdevelopment

Preventing
germination

Study of compound
structure

X-ray exams
cancer

X-ray CT scans

Medicine
Nuclear medicine(FDG-PET)

Sciencetechnology
Isotope batteries

Cancer treatment
Graphical Flip-chart of Nuclear & Energy Related Topics, Japan Atomic Energy Relations Organization, 2016

6

Types of radiation
ionizing
radiation

X-ray, synchrotron radiation
gamma ray, annihilationelectromagnetic wave
(indirectly ionizing radiation)alpha raybeta ray

Radiation

charged particle

electron beam

(directly ionizingradiation)

proton beam
deuteronparticle beam

heavy ionfission productuncharged particle

neutron beam(indirectly ionizing radiation)

non-ionizing
radiation

micro wave, infrared, visible
light, ultraviolet ray

Electromagnetic Spectrum
electric field

7

𝐸 = ℎ･ν =energy propagationh : Planck constantν : frequency
c : light speed
𝜆 : wave length

forward direction
magneticfield

wave length

Energyvisible light1010

108106

gamma-rays
Photons
X-rays10-16ℎ𝑐
𝜆

10-14

10-12

104

102

110-2

10-4

infrared
10-8

10-6

Micro wave

10-4

10-2

1T
1 XU (10-13 m)

10-8

10-10

10-12

eV

radio wave

ultraviolet
10-10

10-6

1 nm

1 µm

Radiation therapy X-ray imaging

Light

VHF HF MF

LF

102

104

11G

1 cm

Microwave

1M
1 kmwave length
106
1k

TelevisionmHz
frequencyBehavior of radiation in a magnetic field
gamma rays
(electromagnetic radiation)neutralalpha rays
(helium nuclei)
positively charged

beta rays(electrons)
negatively charged

Pb container

Magnetic field

Radium-22689Physics of Radiation and Radioisotopes

Structure of matter10protons (8)positively charged

hydrogenHnucleus

O
oxygenHneutrons (8)H 2Owaterelectrons (8)neutralnegatively charged

MatterMolecule

AtomNucleus~ 1.7 m~ 10-9 m~ 10-10 m~ 10-14 m(human body)

11

Atomic notation
Mass number(number of protonsand neutrons)

Carbon

14

C
6

Atomic symbol

Atomic number(number of protons)

14

C, C-14, Carbon-14

Nuclide : type of atom or nucleus characterized
by a specific number of protons and neutronsIsotopeIsotope

12- nuclide that have the same number of protons
but differing numbers of neutrons (or mass number)Radioisotope - isotope that has an unstable nucleus and emit radiation.
In Japan, radioisotope is abbreviated as “RI”.

Hydrogen (H)Deuterium (D)Tritium (H)β- rays

1H

Atomic number
Mass number
ProtonNeutron

2H

3H

Emission of alpha (α) rays (α decay)

13

Helium nucleus(4He)
α raysprotonneutron

22

Transform

226Ra

222Rn

Radium-226

Radon-222

protonneutronprotonneutron

88
138

86
136

Decay (Disintegration) - It is to change into another nuclide by itself while emitting
radiation. Such ability or intensity is called radioactivity.

Amount of radioactivity - unit (Bq, Becquerel)
the number of decay events per second

Emission of beta (β) rays (β decay)

14

electronneutronTransform

protonelectron

β raysTransform

3H
Tritium
protonneutron3He
Helium-3

12

protonneutronstable2
1

Positively charged positrons (β+ rays) can also be emitted.

Emission of gamma (γ) rays

15

β- rays (electron)
excited nucleus
Transform

γ raysCoblt-60
protonneutronNickel-60
protonneutron2832(electromagnetic wave)

2733

stable state

Nickel-60
protonneutron

2832

cooling

When an atomic nucleus is in an excited state after decay,
it emits gamma rays (photons).

Radioactive decay (half-life, T )16 Radioactivity decreases as an exponential form with a constant decay rate Half-life is the time required for a quantity to reduce to half of its initial radioactive value A radioisotope has a inherent half-life
A = A0 exp(-λt) = A0 (1/2)t/T
the number of 16 atoms

atom
atom after decay

Activity

3H

radiation
8 atoms14 atoms

1/2
1/4
1/8
1/16
0T

2T

3T

4T

5T

λ : constant decay rate
= ln 2 /T = 0.693 /T

Time

12.3 years
14C5730 years
32P
14.3 days
51Cr
27.7 days
99mTc
6.02 hours
125I
60.2 days
131
131I
8.0 days134
134Cs
2.1 years
137
137Cs
30.1years
238U
4.5 billion years
40K 1.28 billion years

17

Difference between "Radiation" and "Radioactivity"
The two words are very similar and easily confused in JapaneseLight rays
light bulb

Radiation
isotopefirefly- isotope
firefly light - radiationRadioactivity
leakage

Radiation
leakagelight source
leakage

100 watts

100 Bqability to glow

radioactivity(lumen)（Becquerel）

light leakage

Radioactive material is leaking

Mechanism of nuclear power generation
Thermal power
generation

Power generation

oil coalnatural gas

Pressurized water reactor (PWR)

turbineburning fossil fuels

18

steam
generator
uranium fuelSteam is generated by asteam generator using
high-temperature,
highpressure water produced
in a nuclear reactor.

fission

Nuclear power
generationtransformer

In 2010, nuclear power
accounted for about 30% ofJapan's total electricity.

pressurizer
steam

control rod

water

Source: Nuclear Consensus 2012
In March 2023,
Kansai Electric Power 5 units,
Kyushu Electric Power 3 units inoperation(about 6% of total electricity inFY2021)

generator

steam
generator

water

fuel

turbinecoolantpumpcondenser
water

spillwaycooling water(seawater)

reactor pressure
vesselwater pump

Fission and fission products
FissionThe fission of Uranium-235 produces
radioactive "fission products".

neutronUranium-235

・Strontium (Sr)-90
large amount of energy
Fissionfragment

neutron・Iodine (I)-131
・Cesium (Cs)-134

・Cesium (Cs)-137

Fissionfragment

neutron

19

etc
Uranium-235

neutronUse for nuclear power generation
and atomic bomb

emit radiation

20

X-ray (bremsstrahlung) generation

Bremsstrahlung X-rays

screechelectronBremsstrahlung X-rays
electron(energy, Ee)Atom(electromagnetic waves)(energy, Ex)
Characteristic
X-raysnucleuselectron(energy, Ee - Ex)

When electrons flying at high speed near a nucleus are braked by the nucleus
strong positive electric force, X-rays called bremsstrahlung are generated. In
addition, there are also characteristic X-rays.

Structure of X-ray tube
Filament

Cathode21
accelerating electrons
with a high voltage

thermal electrons

Anode

Focusing electrode− Glass tube

X-rays＋(Bremsstrahlung and characteristic X-rays)
objectfixed anode X-ray tube

rotating anode X-ray tube

Generation of radiation
Radioactive sign

X-rayelectromagnetic wave

alpha rayHelium nucleus

beta rayelectronpositron

gamma rayelectromagnetic wave

Atom

One of hazard symbols

It is said that the central circle
is a radiation source and thethree blades, a trefoil, represent
radiation - alpha, beta andgamma rays.

22

23

Radiation generator (accelerator)
Generation of electron beams, proton beams, heavy proton beams,
neutron beams, etc.
A small cyclotron capable ofproducing short half-liferadioisotopes for PET study• Cyclotron• Synchrotron(self shielding type)

Spring-8

Synchrotron radiation• Synchrocyclotron• Linear accelerator (LINAC)
Radiation therapy• Van de Graaff accelerator

Sumitomo Heavy Industries(CYPRIS-HM12S)• Cockcroft Walton accelerator

A common examination to discovercancer is 18F FDG-PET scan

24

Property of radiation
1) Distance-inverse square law
Intensity I0Intensity I

point source

I =0

Unity: 1

I0x2

distance : x2) Interaction with matter
I = I0 exp(-µx)
transmission

attenuation

absorption

I0

thin matterscattering

thick matter

Ix

25

Ionizing radiation
nucleusionization

ion pairfree electron

nucleusnucleusStable atomcation

orbital electron

excited stateradiation energy

Ionization by radiation

26

When radiation passes through a material, it gives its energy to atoms and molecules
in its path, causing ionization and excitation.

material
direct ionizationalpha ray
Helium nucleus(+)

direct ionization

beta rayelectron(-) or (+)
short wavelength

gamma ray
X-ray
electromagnetic wave

scattering
cationelectronlong wavelength

indirect ionizationEffect of X-rays scattering

27(Irradiation with open X-rays)

door

Scattered X-rays
humanshield

X-ray detector
X-ray tube

transmission

ObjectPenetrating power of radiation

28

alpha raybeta raygamma ray
X-ray
neutron beam

paperplastic plate lead platewater

Radiation shieldingalpha rays shielding

gamma rays shielding

beta rays shielding29

Penetration of radiation within the body30

What happens when radiation hits the human body?

radiation
human body
Physical process(ionization, excitation)

direct action

chemical change[ ＜10-16 second ]moment[ 10-14 second ~ hour ]nearly instant to short timeindirect action

biological effects[ minute ~ year ]acute or early, late31

Units of radiation and radioactivity
sourceenergy (eV)airradiation exposure (C/kg)
How much can γ(X) rays
ionize the air?

radiation
radioactivity (Bq)32material

absorbed dose (Gy)How much radiation energy
is absorbed by matter?

humandose equivalent (Sv)
What is the effect on humans?

Dose received by a specific tissue of the human body-- equivalent dose (Sv)(= radiation weighting factor wR × absorbed dose (Gy) )Dose that evaluates the sum of effects on various tissues of the human body(= tissue weighting factor wT× equivalent dose (Sv) )-- effective dose (Sv)33

Detection of Radiation

Interaction between radiation and substancesalpha rayneutronnuclear reaction

34

photographic effectlithium

scintillation
ionization

Radiation gives energy to substances → detection and measurement(ionization, excitation)

Principles of radiation measurement
1. Utilization of ionization of air or gas
Gas filled detectors : ionization chamber, Geiger–Müller (GM) counter,
proportional counter, etc

2. Scintillation of solid or liquid materials
Detectors : solid scintillation counter, liquid scintillation counter3. Utilization of solid state materials generating electronpositive hole pairs
Solid state detectors : silicon (Si), germanium (Ge) semiconductor
cadmium telluride (CdTe) semiconductor,
cadmium zinc telluride (CZT) semiconductor

4. Chemical reactionDetectors : X-ray film, autoradiography, film badge

35

Detection by gas ionization
Ionizationchamber36

current
Battery

gasradiationA
cationcurrent

Ammeter

electron
When radiation passes inside a chamber, it causes ionization of gas atoms, separating atoms into cations and electrons.
Separated electrons and cations are attracted to the electrodes, causing a current to flow. This is converted into electric
signals, which are then measured as the amount of radiation.

Detection by scintillation of materials

37

generation of one electrical pulse

Scintillator

one radiationdetection

Photo multiplier

Convert to electron
amplify electrons

Electronic signals

electronic signal

⇒

light
one radiation
radiation ⇒light ⇒measurement

38

Scintillation detector
Solid scintillator

Liquid scintillator

Gamma rays measurement

Beta rays measurement

radiation ⇒light ⇒electronic signal⇒

measurement

Radiation measurement (semiconductor detector) 39
Utilization of solid state materials generating
electron-positive hole pairs
Good energy resolution

Comparison of energy spectra detected for Cs-134
Ge (Li) semiconductor detector

NaI scintillation detector

Cs-134796 keV

569 keV

605 keVCounts/channel

Counts/channel

605 keVGe (Li) semiconductor detector

796 keV

563 keV
802 keV

ChannelCs-134ChannelSurvey meters40

portable handheld radiation detectors

Ionization chamber type

Geiger–Müller (GM) type

Scintillation typefor γ‐ray ambient dose ratemeasurement

for contamination detection,highly sensitive to β-particles

for γ‐ray ambient dose ratemeasurement

Radiation detection

Inspection of surface contamination with GM survey meter 41

Detecting radioactive contamination

Hand-foot-cloths monitor

42

Radioactive contamination inspection for radiation workers(when leaving a radiation controlled area)

Geiger–Müller (GM) type

Inspecting for hands and foots

Inspecting for lab coat

Instruments for measuring personal external exposure 43
Radiation exposure• External exposure
Exposure due to radiation from radiation sources outside the body

• Internal exposure
Exposure due to radioactive materials inside the body

Cumulative exposure dose

• Worn on the body for 1‐3months• Cumulative dose measured
by the manufactures

Optically stimulated luminescence(OSL) dosimeter(badge type)Radiophoto-luminescence(RPL) glass dosimeter(badge type)

Electronic personal dosimeter(direct reading display-type of cumulative doses)(ring type)• Radiation workers receive
each personal external
exposure dose reportElectronic personal dosimeter(with alarm function)

How to wear personal exposure dosimeter

44

Purpose : estimation of equivalent dose and effective dose for external exposure

Chest

Belly

Single use

BackNeck and one inside
the lead apron

Chest and finger

Multiple use

Internal exposure dose measurement

45

Measuring and estimating internal exposure dose from radioactive materials ingested
into the body

1. Whole‐body counter methodMeasuring gamma rays emitted directly from the body byan external large detector

2. Nasal smear method
A simple method to determine the presence or absence ofinhalation intake
Sampling by smearing the nasal cavity with a cotton swab
with filter paperStand‐up whole-body counter

3. Bioassay method
Measurement of radioactivity of radioactive materials
contained in excrement (urine, feces, saliva, exhaled breath)and body tissues (skin, hair, blood), etc

Result of measurement ofpotassium (K)-40 in the body

4. Measuring method of radioactivity concentration in airOn-site measurement of radioactivity concentration in air bysampling a gas with a dust monitor or gas monitor