East Asian Workshop, Mito, Japan, 2006 IRB CRPA1 SOME ASPECTS OF SOLID STATE DOSIMETRY IN EUROPE...

East Asian Workshop, Mito, Japan, 2006

IRB CRPA 1

SOME ASPECTS SOME ASPECTS OF SOLID STATE DOSIMETRY OF SOLID STATE DOSIMETRY

IN EUROPEIN EUROPE

Mária Ranogajec-Komor

Ruđer Bošković Institute, Zagreb (IRB)Croatian Radiation Protection Association (CRPA)


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OUTLINEOUTLINE

• IM (Individual monitoring) Implementation of standards in IM Integration of dosimetric methods for external

exposure Quality control and reliability of reported doses

• MD (Medical Dosimetry) X-ray diagnostic (children) CT (of head)

• EM (Environmental monitoring) Dosimetry systems Intercomparison


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Why is IM, MD and EM important?

Nuclear power plants in EuropeThe art of life lies in a

constant readjustment to our surroundings. Okakura Kakuzo Japanese scholar, 1863-1913


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• Diagnostic and therapeautic X-ray units: Most of European countries are in the 1st cathegory according to the number of units/1000 inhabitants

UNSCEAR Report to General Assembly, (New York, UN) (1993).


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• Other medical and industrial application of ionising radiation

• Dosimetry research facilitiesDatabase for EU+Schwitzerland, August 2004http://www.eurados-db.npl.co.uk/EURADOS_facilities_summary_html


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IM: IM: Implementation of standards

• Various standardisation/ accreditation/ approval bodies are in each country

• The accreditation bodies in Europe operate within mutual agreements.

• Numerous existing standards (ISO, IEC, IAEA, national) and documents of relevance like international recommendations, technical reports (ICRP, ICRU, IAEA, EUR, RPD, national).

Harmony is needed in standards


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IM: IM: Implementation of standards

• ISO/IEC 17025 represents the best available techniques for the quality of laboratory work (ISO and IEC are meant for manufacturers and industry).

• IEC 1066 (1991) for IM and EM

ISO: International Standard Organization

IEC: International Electrotechnical Committee


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System of IMIM service in Croatia (HR)

STATE OFFICE OF RP

Registration

ACCREDITED INSTITUTIONS

USERS

MINISTRY OF HEALTH

Use

d do

sim

eter

s

New

dos

imet

ers

Rep

ort

Measured dose

Report: overdose, lost dosimeters, etc.

Database


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A catalogue of IMIM services within Europe

• Total number of estimated IM services: 200

• Catalogue of dosemeters and dosimetric services within Europe: 104

Results: The data indicates that the services in Europe almost exclusively monitor their workers in terms of personal dose equivalent (Hp(10)).

Calibration: air kerma Personal dose: Hp(10)


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Data on IMIM dosimetric services who responded to the questionnaire

Country code

Services Workers controlled

Dosimeter system for photons

B 3 6000 1F, 2TLD

BG 5 12450 1F, 5TLD

CZ 4 20420 2F, 2TLD

D 8 52900 1F, 2TLD, 3V

EST 1 1050 1TLD

F 8 242800

H 2 30000 1F, 1TLD

HR 2 3700 1F, 1TLD

I 12 44170 2F, 10 TLD

PL 3 35000 2F, 3TLD

YU 2 5100 2TLD

29 104 727640 30F, 69TLD, 5V

F: film (443 000)

TLD: (273 070) thermoluminescent

V: various (glass, electronic, OSL)(11 570)

6F, 2TLD1 RPL, 5F, 2TLD

F: film (200 000)

RPL: glass (200000)

TLD: (273 070) thermoluminescent

V: various (glass, electronic, OSL)(11 570)


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Data on IM IM dosimetric services in Croatia (HR) – 2006

Accredited institution

No of workers

Dosimeter system

EKOTEH 2677 F (188 TLD)

IMI 1024 F

IRB 1222 TLD

Total 4681 2F, 1 TLD

Data from SRP, D. Kubelka


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IM:IM: Electronic dosemeters and other new developments

Objective: First evaluation (implementation and use) of Active Personal Devices (APD) for IM• Legal status• Technical characteristics• Advantages and disadvantages

Used in NPP – Energy dependence and mechanical properties critical – differences in intercomparison – increasingly used


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Inventory of problems of non-dosimetric origin in individual monitoring that impair the quality of external dose assessments: lost, mislaid or damaged dosimeters, failure of processing equipment including data processing,...

88 services from 26 European countries participated in the study.

Overview on QC actions and possible sources of uncertainties was analysed in Europe.

QC and reliability of IMIM systems (external radiation)


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Introducing new dosimetry systems RPL-(France)

Proposal of WG2 of Eurados

Perspectives in IMIM


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EURADOS (European Radiation Dosimetry)

Membership:recently 50 voting and 200 associate members

Activity:several Working Groups

4. Numerical dosimetry

7. Internal dosimetry

5. Air crew dosimetry

6. Computational dosimetry

3. EM2. IM1. Irradiation facilities

9. RP of medical staff

http://www.eurados-online.de/

8. Complex mixed fields


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Produce every four years a report onCurrent state of the art

External photon, beta, neutronInternal, direct, indirectWorkplace, external, radon, aircrew

Address a special topicE.g. electronic, neutron, beta, extremity

Organise every four years an intercomparisonMonitoring services external, internal radiation

Organise every four years a workshop

Perspectives in IMIMProposal of WG2 of Eurados


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MEDICAL DOSIMETRYMEDICAL DOSIMETRY

• X-ray diagnostic

• Therapy

• Nuclear medicine

– conventional radiology– CT– interventional radiology

77% Natural radiation20% Medical irradition 3% Other man-made irradiation

20%

3%

77%


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MEDICAL DOSIMETRYMEDICAL DOSIMETRY1. Dose measurements after the characterisation of

dosimetry systems

2. The exact knowledge of doses delivered to different

organs or to the whole body is needed (patient and

phantom)• to estimate the exposure of population

• to estimate the risk

• to specify radiation protection measures

• to assess the justification of the procedurein terms of overall patient benefit and safetymeasures


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The determination of the doses received by patients in X-ray diagnostics is complicated

• very low doses at low and variable energies

• considerable variation in radiation doses delivered to patients (different X-ray equipment, different personnel)


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Use of baby-fix and arrangement of dosimeters


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Lateral chest radiography (age: under 3 years)

Posteroanterioral (PA) and lateral chest radiography (age: 3 years and older)


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Age (years)

Back

Chest

Dose Thyroid

(mSv) Armpit

Eye

Gonad

0 - 3 0.12 0.07 0.08 0.05 0.08 0.07

3 - 6 0.17 0.15 0.12 0.10 0.05 0.04

6 - 9 0.31 0.29 0.27 0.13 0.04 0.02

9 - 12 0.36 0.26 0.16 0.17 0.03 0.02

> 12 0.33 0.25 0.20 0.18 0.07 0.03

Mean 0.26 0.20 0.17 0.13 0.05 0.04

SD 0.11 0.09 0.05 0.05 0.02 0.02

Mean value of the surface skin dose measured on children during X-ray diagnostics of chest


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MEDICAL DOSIMETRYMEDICAL DOSIMETRYStandard deviations of dosimetric

measurements

Energy SD (%)

SSDL 80 kev ± 4

routine X-ray unit

90 kV ± 21

on patients variable ± 100


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MEDICAL DOSIMETRYMEDICAL DOSIMETRYFactors

which influence the standard deviation

technical conditions (kV, mAs), feature of patients (age, height, weight

etc.), absorption and scattering of radiation, PA and lateral projection different X-ray units working method of personnel.


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MEDICAL DOSIMETRYMEDICAL DOSIMETRYRisk estimation of radiation damage

in X-ray diagnostics of respiratory tract of children

*ICRP, Publ. 60, 1990**Number of children examined 1 patient with damage


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3. For the risk estimation highly statistical dose measurements are needed

2. Importance of standardisation of technik and methods reduction of large variation in absorbed dose


1. The evaluated risks are not alarming all patient protection measures should be carried out

SUMMARY


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MEDICAL DOSIMETRY-CTMEDICAL DOSIMETRY-CT

The highest doses result from CT (in diagnostics)

CT accounts for 2-3% of all X-ray examinations - it contributes about 20% of the population doses.

Important task: radiation protection of patients.


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MEDICAL DOSIMETRY-CTMEDICAL DOSIMETRY-CTDosimetry: TLDCT: SOMATOM DR-H SCT-4500TE

(Siemens) (Shimadzu) Installation: 1987, Hospital A 1994, Hospital BCondition, number of patients, number of dosimeters


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0

10

20

30

40

50

5 15 25 35 45 55 65 75

Dose (mGy)

Nu

mb

er

of

me

asu

rem

en

ts

MEDICAL DOSIMETRY-CTMEDICAL DOSIMETRY-CTDistribution of radiation doses for both eyes

measured during CT of the head


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MEDICAL DOSIMETRY-CTMEDICAL DOSIMETRY-CTThe ratio of the minimum to the maximum of the measured surface doses varies by a factor of

4 to 7 (gonades, chest, thyroid).10-11 (eye lens)


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the dose varies according to the position, size and shape of the patients' bodies;

the distance of the primary X-ray beam from the organ significantly varies from one patient to another;

the number of scans varied by a factor of 2;

the total mAs also varied by a factor of 2.

This is understandable when we consider the following:


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• 3 in New Zealand,

• 5 in Sweden and the United Kingdom

• 3.5 in Japan (depending on the CT scanner unit).

Measured on a hypothetical average adult phantom.


• USA: 250 CT systems - typical dose is 22-68 mGy

• Japan: from 18 to 80 mGy (adults).

Factor of dose variations:

Literature (UNSCEAR, 1993):Surface doses during CT of head:


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Dose measurements in medicine - TL and RPL

dosimetry

Benefits:

facilitate the control of X-ray equipment;

identify equipment requiring additional

safety measures;

facilitate patient risk assessment

aid in directing efforts toward reducing

total radiation doses.

MEDICAL DOSIMETRYMEDICAL DOSIMETRY SUMMARY


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From the point of view of radiation protection of

patients, an optimum factor for X-ray

examinations should be decided by considering

not only the image quality but also the

absorbed dose resulting from medical

procedures.

This aim can be achieve by frequent dosimetry by permanent education of personnel.

MEDICAL DOSIMETRYMEDICAL DOSIMETRY CONCLUSIONS


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ENVIRONMENTAL DOSE ENVIRONMENTAL DOSE MEASUREMENTMEASUREMENT (EM) (EM)

PROBLEMS:

• society worries about environmental quality

• human activities can increase radiation dose in the environment

TASK:

• collection of well documented data on radiation doses in the environment


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Environmental radiation external exposure

Terrestrial Cosmic

Dubrovnik, Croatia

Fujijama, Japan

EMEM


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EMEMREQUIREMENTS for dose measurements:

• to measure the man-made contribution to environmental radiation (1:10)

• to follow the changes in natural environmental radiation (Early Warning Network Systems)

• under variable environmental conditions (UV sunlight, humidity, temperature)

SOLUTION:

TLD, RPL, in-situ gamma spectrometry


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EMEM• their application to environmental dosimetry requires

performance under laboratory and field conditions

• performance testing and procedural specifications may be found in national and international standards

International Electrotechnical Committee (IEC). TLD Systems for Personal and Environmental Monitoring. International Standard - IEC 1066 (1991)


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Test methods for EM EM• Batch homogenity:

• Detection threshold:

• Linearity:

• Energy dependence: 80-100 keV, 137CsE: evaluated valueC: conventional true valuei: number of groupli: half-width of confidence interval

3.0E

EE

min

minmax

3.1C

lE7.0 ii

1.1C

lE9.0

i

ii

RPL

0.96-1.04

0.1

1.52μGy

1.1


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EMEM IIntercomparisonntercomparison

To reach international standards there is a need for INTERCOMPARISONS (large scale)

• US DOE, EML 12 1972-2002

• EC 1984-1994

• NRPB 1985

• COMECOMA 1989

• EURADOS 1999-2002

• to improve environmental monitoring methods• to serve as periodic quality control

AIM:


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IIntercomparison of ntercomparison of EMEM

Field irradiation

Lab irradiation


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PProtocolrotocol ofof EMEM IIntercomparisonntercomparison

3 sets of RPL/TLDfieldfading (pre-irradiated)transport

calibration + controldosimeters - in the shield

HR shield

H D1

D2

H1

H2

HR1 HR2

shield shieldD


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IIntercomparison in ntercomparison in EMEM

• The suitability of RPL and new high sensitivity TL detectors for EM

• shorter monitoring period

• influence of climatic conditions on fading and dose according to the season or the location

Expected answers


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Perspectives in EMEM

• to support a suitable infrastructure for the characterisation and intercomparison of EM systems

RPL system in RBI, Zagreb


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PERSPECTIVESPERSPECTIVESThe important thing is not to stop questioning.

Albert Einstein

US (German-born) physicist (1879 - 1955)


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PERSPECTIVESPERSPECTIVES

HVALA

有難うございました

The author is grateful to Chiyoda Technol Corporation, Japan for the support of participation

East Asian Workshop, Mito, Japan, 2006 IRB CRPA1 SOME ASPECTS OF SOLID STATE DOSIMETRY IN EUROPE...

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