ARPANSA - Primary Standards Dosimetry Laboratory (PSDL) Reportssdl.oap.go.th/ssdlonline2/wp-content/uploads/2019... · Dosimetry Laboratory (PSDL) Report Duncan Butler Workshop on

ARPANSA - Primary Standards Dosimetry Laboratory (PSDL)

Report

Duncan Butler

Workshop on Building Asia-Pacific Individual Monitoring Service (IMS) Capabilities toward Regional Sustainable Network.

At Pullman Bangkok King Power Hotel, Bangkok Thailand 18-20 March 2019

1

ARPANSA

1. Structure of organization

2. Personnel

3. Facilities and conditions

4. Equipment

5. QA/QC programme

6. Number of service/ samples

7. Future research/ new topics

2

In Melbourne, Australia

Structure

3

Office of the CEO

Radiation Health

Services

Corporate Office

Medical Radiation Services

Regulatory services

PSDL

ACDS

Medical Imaging

ARPANSA CEO

Primary Standard Dosimetry Laboratory

Australian Clinical Dosimetry Services

~ 140 staff in totalConcerned with radiation protection (UV, ionising, mobile phones, EM, nuclear safety…)

Personal Monitoring

UV

CTBT

…

ARPANSA: PSDL Staff

4

PSDL staff (Nov 2018)

Viliami TakauAnna HaytonTracy Bailey (0.4)Chris OliverMax Hanlon (0.6)Clare SmithPeter HartyCallum WatsonDuncan Butler (on secondment for 1 year)

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ACDS : Australian Clinical Dosimetry Service

• Checks radiotherapy doses in hospitals

6

By mail: Al2SO4 OSLDsOn-site

ACDS

7Director, Dr Jessica Lye

Personal Radiation Monitoring Service

8

PSDL• Maintain primary standards for radiation dosimetry

• Provide personal monitor irradiations

• Calibrate equipment

- Our focus is on medical radiation

Research/projects:

• Monte Carlo modelling of ion

chambers

• Small field dosimetry

• IAEA Hp(10) comparisons

• Adopting ICRU90 data

• Spatial response of radiation detectors9

Laboratory facilities

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60Co Linac (2009) New linac (2019)

40 – 320 kVp X-rays 10 – 100 kVp X-rays Am/Be neutrons

137Cs – not shown

Protection-level irradiations

• Have put irradiators into storage (!)

• Can no longer perform low dose rate calibrations

but

• Personal monitor irradiations can be performed with the high dose rate sources (1 mSv/min)

• Attenuate beam for many protection calibrations

11

New linac at ARPANSA

12

Pouring concrete for shielding

13

14

Official opening March 2019

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Official opening March 2019

Equipment – Primary Standards

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Cavity Chamber for air kerma in 60Co

Free air chambers for air kerma in X-ray beams

10-100 kVp 40-320 kVp

Graphite calorimeter for absorbed dose in 60Co and

linac beams

Graphite calorimeter in use…

17Measuring absorbed dose to graphite in linac beam

Example: Irradiation using an ISO Narrow Series X-ray beam

18

Radiation source

Primary standard(ARPANSA free air chamber)

Example: Irradiation using an ISO Narrow Series X-ray beam

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Radiation source

Primary standard(ARPANSA free air chamber)

Air kerma here

Uncertainty in kerma is 0.4% (k=1)

Example: Irradiation using an ISO Narrow Series X-ray beam

20Uncertainty in Hp(10) > uncertainty in K

Radiation source

Equipment – Electrometers

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Use several PTW UNIDOS Webline electrometers- used for protection-level and therapy-level measurements

Many radiotherapy ionization chambers and solid state detectors

Equipment – Other

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Exradin A4 and A5 ionization chambers

• Temperature (thermistors and PRT)

• Pressure (Druck 141)• Humidity

• Voltage calibrator • Standard resistors

All traceable to national standards

Personal monitor irradiations

• 60Co…1250 keV

• 137Cs…662 keV

• kV X-rays…40 – 320 kVp

ISO Narrow Series X-rays

ISO Wide Series X-rays

ARPANSA therapy beams

• Am/Be neutrons

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QA program for a PSDL

1. International comparisons of primary standards “Key comparisons” – in Asia Pacific APMP and with BIPM in Paris.

2. Supplementary and bi-lateral comparisons

3. Internal checks: records of constancy

Accreditation of services to ISO 17025(17025 = standard for

calibration laboratories)

On-site peer reviews

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1. Example: key comparison air kerma in kV X-rays

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1%

Laboratory

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2. Example: Bi-lateral comparison Japan-Australia

History (QC charts)

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Example: Co-60 air kerma measurements

QA/QC for personal monitoring

ARPANSA PSDL provides exposures for:

Commissioning

• Energy response (from kV X-rays, 137Cs, 60Co)

• Linearity (0.01 mSv to 100 mSv)

(also establishes stdev versus dose)

• Fading

Ongoing QA

• Monthly 1 mSv control monitors (20)28

IAEA-ARPANSA Comparison of Personal Dosimeters for the Asia

Pacific Region 2018

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Dosimetry course for medical physicists

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Ion chamber spatial response

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Published in Nuclear Inst. and Methods in Physics Research A 914 (2019) 15–24

Response maps in B-fields – in preparation

Measuring small fields: application of TRS-483

• Used protocols reference conditions:

– Water phantom (PTW Blue Phantom II), Z= 10 gcm-2, SSD = 100 cm.

• Elekta Synergy linac (6 MV WFF X-ray beam)

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Comparison of detector types

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0.6

0.7

0.8

0.9

1.0

5 15 25 35 45

Ou

tpu

t fa

cto

r (u

nco

rre

cte

d)

Cone size (mm)

Uncorrected output factor for cones

MD 1 MD 2 MD 3 MD 4

e- diode EFD p diode PFD

SRS PP 31014 PP 31016 CC04

0.6

0.7

0.8

0.9

1.0

5 15 25 35 45

Ou

tpu

t fa

cto

r (c

orr

ect

ed

)

Cone size (mm)

Corrected output factor for cones

MD 1 MD 2 MD 3 MD 4

e- diode EFD p diode PFD

SRS PP 31014 PP 31016 CC04

Monte Carlo calculations of kQ

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Figure 1: Visualisation of interactions inside a NE2571 ionisation

chamber with photon source incident from the top. The yellow marks

represent photons, and the red marks electrons. Cross section

enhancement is used to increase the production of electrons.

CONTACT ARPANSA

Email: info@arpansa.gov.auWebsite: www.arpansa.gov.auTelephone: +61 3 9433 2211

Freecall 1800 022 333General Fax: +61 3 9432 1835

THANK YOU

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