Protection in Laboratory work Mats Isaksson prof Department of radiation physics GU matsisakssonradfysguse Fundamental principles ICRP Justification Optimisation ID: 587034
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Slide1
Radiation
Protection in Laboratory work
Mats Isaksson, prof.
Department
of
radiation
physics
, GU
mats.isaksson@radfys.gu.seSlide2
Fundamental principles (ICRP)
JustificationOptimisation
Application of dose limitsSlide3
Fundamental principles (ICRP)
Justification“Any decision that alters the radiation exposure situation should do more good than harm.”Slide4
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)Slide5
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 existingSlide6
Radiation doses 1
Absorbed dose
(unit 1 Gy = 1 J kg-1)Used in e.g. radiation therapy to specify the dose to the tumorDifferent radiation qualities (a, b, g, n) can cause different degree of harm – weighting necessarySlide7
Radiation doses 2
Equivalent
dose (unit 1 Sv = 1 J kg-1)Used to calculate the dose to a tissue or organWeighting factors for different radiation qualities given by ICRPCan be estimated by measurable quantities e.g.personal dose equivalent Slide8
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 doseEnables a comparison of risk from different exposure distributionsSlide9
Radiation doses 3´
Illustration to effective doseSlide10
Radiation doses 4
Effective dose
(unit 1 Sv = 1 J kg-1)Weighting factors for different organs and tissues are given by ICRPCan be estimated by measurable quantities e.g.ambient dose equivalentSlide11
”The bottom line”
Medical
diagnosticsCosmic radiationCaesium-137Naturally occurring radionuclides in foodRadon in indoor airK in the bodySoil and building materials
Drinking
water problem
Effective
dose
/
mSv
a
-1
Never-smoker
Smoker
(and ex.
smoker
)
Reindeer
keepers
Frequent
air
travellerSlide12
X-ray and nuclear medicine
From ”Nuklearmedicin” by Sten Carlsson and Sven-Eric Svensson (
available at http://www.sfnm.se/)Slide13
Radiation
sourcesRadioactive sources Unsealed – liquid, gas, powder SealedTechnical equipment X-ray machines AcceleratorsSlide14
Ionizing
radiation from
radioactive elementsSlide15
Generation
of
x-rays X-ray spectrumX-ray equipmentSlide16
Radiation safety in the
labExternal
irradiationShort range radiation, e.g. a, mostly harmless when the source is outside the bodyb-emitters may cause severe skin damage if they are in contact with naked skinSlide17
Radiation safety in the
labInternal
irradiationRadioactive substances in non-sealed sources (gas, liquid, powder) cause special concernCan enter the body through ingestion, inhalation, wounds or through the skinSlide18
Radiation
safety in the labExternal irradiation: Factors to be consideredTime – more time spent in the radiation field gives a larger radiation doseDistance – inverse square law (for point source)Shielding – shielding material depends on the source (a, b, g)Slide19
Radiation safety in the
labExternal
irradiation: Inverse square lawSlide20
Radiation safety in the
labExternal
irradiation: Inverse square lawSlide21
Practical ALARA
Practice
before working with the real sourceEducation before workSeparate office and lab workWear protective clothing and gloves
All
labs
should
be
marked
with
signs
Eat
, drink
etc
outside
the
labSlide22
Radiation safety in the
labExternal
irradiation: Shielding: b-range in mmElectron energy / keVAlFePbPlexi500.02
0.008
0.009
0.04
100
0.07
0.03
0.03
0.1
500
0.8
0.3
0.3
1.5
1 000
2.1
0.8
0.7
3.8
H-3
: 19
keV
;
C-14
: 156
keV
;
S-35
: 167
keV
;
P-32
: 1711
keV
Slide23
Radiation safety in the
labExternal
irradiation: Shielding: g HVL in mmPhoton energy / keVAlCuPb5014
0.5
0.09
100
16
2
0.12
500
30
10
4.2
1 000
42
14
9
I-125
: 35
keV
;
Tc-99m
: 140
keV
;
I-131
: 365
keV
;
Y-88
: 1836
keVSlide24
Radiation
safety in the labInternal irradiation: Factors to be consideredActivity – the larger the activity the larger the radiation dose (for a given radionuclide)Radionuclide – amount of energy per disintegration; type of radiationMetabolism – element and chemical form determine the residence time in the body and concentration in organsSlide25
Radiation safety in the
labInternal
irradiation: Effective half-lifeRadionuclideT1/2,physT1/2,biolT1/2,eff
H-3
12 y
10 d
10 d
C-11
20 m
10-40 d
20 m
C-14
5 700 y
10-40 d
10-40 d
I-125
60 d
140 d
40 dSlide26
Radiation safety in the
lab
Classification of radionuclidesClass A: very high radiotoxicity (ex. a-emitters: Pb-210, Pu-238, Cf-252,…)Class B: high radiotoxicity (Na-22, Ca-45, Co-56, Co-60, Sr-89, In-114m, I-125, I-131, Cs-137,…)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, Tl-201…)Class D: low radiotoxicity (H-3, C-11, Tc-99m,…)Slide27
Deterministic
effects –
approximate threshold values>0,1 Gy Effects on embryo and fetus0,5 Gy Temporary sterility, men2 Gy Cataract4 Gy Temporary hair loss5 Gy Skin erythema6 Gy Permanent sterlility, men
8 Gy
Pneumonia
2-12 Gy Permanent
sterility
,
womenSlide28
Deterministic effects –
whole body irradiation
Lethal dose (50 % of exposed individuals survive): 3-4 GyAcute radiation syndrome – blood forming organs, gastro-intestinal tract & central nervous systemSlide29
Stochastic effects – no
thresholdCancer and hereditary
effectsIncreasing risk with increasing doseRisk factor only applicable on a population levelLNT-hypothesisSlide30
Laws and regulations
Strålskyddslagen SFS 1988:220
Employers obligations Workers obligations Licence demands Waste handling demands Medical examination Young peopleStrålskyddsförordningen SFS 1988:293Slide31
Relevant regulations (SSM)
SSMFS 2010:2 Radioactive
wasteSSMFS 2011:2 Clearance of materials, premises, buildings och groundsSSMFS 2008:25 Radiography SSMFS 2008:51 Protection of workers and the publicSSMFS 2008:28 Laboratory work with unsealed radioactive sourcesSlide32
License from SSM for work with ionizing
radiation
Licensee: University of GothenburgContact person Annhild LarssonRadiation protection expert (GU) Annhild LarssonRadiation protection expert (Rad. Phys.) Mats IsakssonLicense valid to 2016-02-07Slide33
SSMFS 2010:2 Radioactive waste
Revised
limitsDocumentation kept for 5 yearsYearly report to SSM concerning releases to sewageSlide34
*) Will
probably
be revised to 20 mSv in a year, averaged over defined periods of 5 years, with no single year exceeding 50 mSv WorkerStudent 16-18 aPublicYearly effective dose5061Effective dose
/
consecutive
5-year
period
100
Yearly
equivalent
dose
to
lens
of
the
eye
*)
150
50
15
Yearly
equivalent
dose
to
skin, hands and
feet
500
150
50
SSMFS 2008:51:
Dose
limits (
mSv
)Slide35
SSMFS 2008:51: Protection of
pregnant or breast feeding women
Women in fertile ages should be informed of the risks for the fetusPregnant 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
workSlide36
Protected
area (”Skyddat område”)
Category B worker local rules (could be given verbally)signs with the text ”skyddat område” and type
of
source
C
ategory
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 2008:51
CategorizationSlide37
Nuclide
Radio-
toxicity classActivity
/
work
activity
Arb I
(MBq)
Arb II
(MBq)
Arb III
(MBq)
H-3
D
100
1000
10000
P-32
C
10
100
1000
Cr-51
C
10
100
1000
I-125
B
1
10
100
N.B.
Local
restrictions
concerning
max
activity
at
departments
SSMFS 2008:28
Restrictions
on
activity
in
laboratory
work
Arb
I: Risk
of
inhalation
Arb
II: Risk
of
external and internal exposure; small risk
of
inhalationSlide38
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
dosesSlide39
www.arbetsmiljo.adm.gu.se
www.studentlitteratur.se
/#7403-02 (in Swedish)www.stralsakerhetsmyndigheten.seThank you for your patience