Radiation Protection in
Laboratory work
Mats Isaksson, prof.
Department of radiation physics, GU mats.isaksson@radfys.gu.se

Fundamental principles (ICRP)
Justification
Optimisation
Application of dose limits

Fundamental principles (ICRP)
Justification
“Any decision that alters the radiation exposure situation should do more good than harm.”

Fundamental principles (ICRP)
Optimisation
“The likelihood of incurring exposure, the number of people exposed, and the magnitude of their individual doses should all be kept as low as reasonably achievable, taking into account economic and societal factors.”
(The ALARA-principle)

Fundamental principles (ICRP)
Application of dose limits
“The total dose to any individual from regulated sources in planned exposure situations other than medical exposure of patients should not exceed the appropriate limits specified by the
Commission.”
N.B. ”… other than medical exposure of patients…”
ICRP-report 103 identifies three exposure situations: planned, emergency and existing

Radiation doses 1
Absorbed dose (unit 1 Gy = 1 J kg -1 )
Used in e.g. radiation therapy to specify the dose to the tumor
Different radiation qualities
( a
, b
, g
, n) can cause different degree of harm – weighting necessary

Radiation doses 2
Equivalent dose (unit 1 Sv = 1 J kg -1 )
Used to calculate the dose to a tissue or organ
Weighting factors for different radiation qualities given by ICRP
Can be estimated by measurable quantities e.g.personal dose equivalent

Radiation doses 3
Effective dose (unit 1 Sv = 1 J kg -1 )
Used to calculate the whole body dose that gives the same detriment as the actual partial body dose
Enables a comparison of risk from different exposure distributions

Radiation doses 3 ´
Illustration to effective dose

Radiation doses 4
Effective dose (unit 1 Sv = 1 J kg -1 )
Weighting factors for different organs and tissues are given by ICRP
Can be estimated by measurable quantities e.g.ambient dose equivalent

”The bottom line”
Effective dose / mSv a -1
Medical diagnostics
Caesium-137
Naturally occurring radionuclides in food
Radon in indoor air
K in the body
Soil and building materials
Cosmic radiation

X-ray and nuclear medicine
From ”Nuklearmedicin” by Sten Carlsson and
Sven-Eric Svensson
(available at http://www.sfnm.se/)

Radiation sources
Radioactive sources
Unsealed – liquid, gas, powder
Sealed
Technical equipment
X-ray machines
Accelerators

Ionizing radiation from radioactive elements

X-ray equipment
Generation of x-rays X-ray spectrum

Radiation safety in the lab
• External irradiation
• Short range radiation, e.g. a
, mostly harmless when the source is outside the body
• b
-emitters may cause severe skin damage if they are in contact with naked skin

Radiation safety in the lab
• Internal irradiation
• Radioactive substances in non-sealed sources (gas, liquid, powder) cause special concern
• Can enter the body through ingestion, inhalation, wounds or through the skin

Radiation safety in the lab
• External irradiation: Factors to be considered
• Time – more time spent in the radiation field gives a larger radiation dose
• Distance – inverse square law (for point source)
• Shielding – shielding material depends on the source ( a
, b
, g
)

Radiation safety in the lab
External irradiation: Inverse square law

Radiation safety in the lab
External irradiation: Inverse square law

Practical ALARA
• Practice before working with the real source
• Education before work
• Separate office and lab work
• Wear protective clothing and gloves
• All labs should be marked with signs
• Eat, drink etc outside the lab

Radiation safety in the lab
External irradiation: Shielding: b
range in mm
Electron energy / keV Al
50 0.02
100 0.07
500
1 000
0.8
2.1
Fe Pb Plexi
0.008
0.009
0.04
0.03
0.03
0.1
0.3
0.8
0.3
0.7
1.5
3.8
H-3 : 19 keV; C-14 : 156 keV; S-35 : 167 keV;
P-32 : 1711 keV

Radiation safety in the lab
External irradiation: Shielding: g
HVL in mm
Photon energy / keV Al
50 14
100
500
1 000
16
30
42
Cu
0.5
2
10
14
Pb
0.09
0.12
4.2
9
I-125 : 35 keV; Tc-99m : 140 keV;
I-131 : 365 keV; Y-88 : 1836 keV

Radiation safety in the lab
• Internal irradiation: Factors to be considered
• Activity – the larger the activity the larger the radiation dose (for a given radionuclide)
• Radionuclide – amount of energy per disintegration; type of radiation
• Metabolism – element and chemical form determine the residence time in the body and concentration in organs

Radiation safety in the lab
Internal irradiation: Effective half-life
Radionuclide
H-3
C-11
C-14
I-125
T
1/2,phys
12 y
T
1/2,biol
10 d
T
1/2,eff
10 d
20 m 10-40 d 20 m
5 700 y 10-40 d 10-40 d
60 d 140 d 40 d

Radiation safety in the lab
• Classification of radionuclides
• Class A : very high radiotoxicity ( ex. a
emitters: Pb-210, Pu-238, Cf252,… )
• Class B : high radiotoxicity ( Na-22, Ca-45, Co-
56, Co-60, Sr-89, In-114m, I-125, I-131, Cs137,… )
• Class C : moderate radiotoxicity ( C-14, Na-24,
P-32, S-35, Ca-47, Cr-51, Fe-55, Fe-59, Co-57, Co-
58, Zn-65, Y-90, I-123, Tl201… )
• Class D : low radiotoxicity ( H-3, C-11, Tc-
99m,… )

Deterministic effects – approximate threshold values
>0,1 Gy Effects on embryo and fetus
0,5 Gy Temporary sterility, men
2 Gy Cataract
4 Gy
5 Gy
Temporary hair loss
Skin erythema
6 Gy
8 Gy
Permanent sterlility, men
Pneumonia
2-12 Gy Permanent sterility, women

Deterministic effects – whole body irradiation
Lethal dose (50 % of exposed individuals survive): 3-4 Gy
Acute radiation syndrome – blood forming organs, gastro-intestinal tract
& central nervous system

Stochastic effects – no threshold
Cancer and hereditary effects
Increasing risk with increasing dose
Risk factor only applicable on a population level
LNT-hypothesis

Laws and regulations
Strålskyddslagen SFS 1988:220
•
Employers obligations
•
Workers obligations
•
Licence demands
•
Waste handling demands
•
Medical examination
•
Young people
Strålskyddsförordningen SFS 1988:293

Relevant regulations (SSM)
SSMFS 2010:2 Radioactive waste
SSMFS 2011:2 Clearance of materials, premises, buildings och grounds
SSMFS 2008:25 Radiography
SSMFS 2008:51 Protection of workers and the public
SSMFS 2008:28 Laboratory work with unsealed radioactive sources

License from SSM for work with ionizing radiation
Licensee: University of Gothenburg
Contact person Annhild Larsson
Radiation protection expert (GU) Annhild Larsson
Radiation protection expert (Rad. Phys.)
License valid to 2016-02-07
Mats Isaksson

SSMFS 2010:2 Radioactive waste
Revised limits
Documentation kept for 5 years
Yearly report to SSM concerning releases to sewage

SSMFS 2008:51: Dose limits
(mSv)
Worker
50
100
Student 16-18 a Public
6 1 Yearly effective dose
Effective dose / consecutive 5year period
Yearly equivalent dose to lens of the eye *)
Yearly equivalent dose to skin, hands and feet
150
500
50
150
15
50
*) Will probably be revised to 20 mSv in a year, averaged over defined periods of 5 years, with no single year exceeding 50 mSv

SSMFS 2008:51: Protection of pregnant or breast feeding women
Women in fertile ages should be informed of the risks for the fetus
Pregnant women have the right to be relocated
(if not, the effective dose to the fetus should not exceed 1 mSv during the rest of the pregnancy
Breast feeding women should not be exposed to a risk of being contaminated in the work

SSMFS 2008:51 Categorization
Protected area (”Skyddat område”)
Category B worker
• local rules (could be given verbally)
• signs with the text ”skyddat område” and type of source
Category B (max activity per work activity)
• Gamma emitting radioniclides: < 100 MBq
• Beta emitters:
• < 10 MBq for beta energy > 0,3 MeV
• < 100 MBq for beta energy 0,1-0,3 MeV
• No work with open radiography

SSMFS 2008:28 Restrictions on activity in laboratory work
N.B. Local restrictions concerning max activity at departments
Nuclide
H-3
P-32
Cr-51
I-125
Radiotoxicity class
D
C
C
B
Arb I
(MBq)
Activity/work activity
Arb II
(MBq)
Arb III
(MBq)
100 1000 10000
10
10
1
100
100
10
1000
1000
100
Arb I: Risk of inhalation
Arb II: Risk of external and internal exposure; small risk of inhalation

SSMFS 2008:28
Documentation/reporting
Data which should be documented, signed and kept available for concerned personnel:
• Received and stored radioactive substances, and their activities
• Possession of calibration sources
• Results from ventilations and contamination monitoring
• Results from personnel dose monitoring and estimations of internal doses

Thank you for your patience www.arbetsmiljo.adm.gu.se
www.studentlitteratur.se/#7403-02 (in
Swedish) www.stralsakerhetsmyndigheten.se