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Radiation Radiation

Radiation - PowerPoint Presentation

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Radiation - PPT Presentation

Protection in Laboratory work Mats Isaksson prof Department of radiation physics GU matsisakssonradfysguse Fundamental principles ICRP Justification Optimisation ID: 587034

dose radiation ssmfs lab radiation dose lab ssmfs work safety kev 2008 irradiation exposure doses effective external risk body

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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