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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
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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
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In Melbourne, Australia
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Structure
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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
…
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ARPANSA: PSDL Staff
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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
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By mail: Al2SO4 OSLDsOn-site
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ACDS
7Director, Dr Jessica Lye
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Personal Radiation Monitoring Service
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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
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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
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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
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New linac at ARPANSA
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Pouring concrete for shielding
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Official opening March 2019
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Official opening March 2019
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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
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Graphite calorimeter in use…
17Measuring absorbed dose to graphite in linac beam
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Example: Irradiation using an ISO Narrow Series X-ray beam
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Radiation source
Primary standard(ARPANSA free air chamber)
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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)
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Example: Irradiation using an ISO Narrow Series X-ray beam
20Uncertainty in Hp(10) > uncertainty in K
Radiation source
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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
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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
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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
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History (QC charts)
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Example: Co-60 air kerma measurements
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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
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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
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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
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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.
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CONTACT ARPANSA
Email: [email protected] : www.arpansa.gov.auTelephone: +61 3 9433 2211
Freecall 1800 022 333General Fax: +61 3 9432 1835
THANK YOU
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