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Radiation Dose Assessment of Persons Undergoing the Soter RS

Security Screening

David Leslie BHSc, Dip.Med Rad, MIRManager Compliance and ConsultingGammasonics Radiological Services

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Security Screening

• Metal Detector, Chemical Analysis

• X-Ray Backscatter– Body Surface through

clothing– Plastic, Metal, Organic

• mm Wave technology– RF Terahertz range– Active or Passive– 3D showing surface objects

in high contrast

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Security Screening

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Soter RS

• Non invasive• Rapid, 20 sec• Surface plus internal

body• Less privacy issues

(Surface anatomy)• Low contrast

sensitivity

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Soter RS

• Training /Licensing• Image Interpretation

Skills• Whole body absorbed

radiation dose.

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Applications

• Airport Security, Customs

• Gem and Diamond Mines

• Correctional Facilities

– ACT Corrections.

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What’s The Dose

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What’s The Dose

• Several studies-– Based on assessment of skin entrance dose conversion.– 2-5 uSv per scan.

• Problems –– Beam geometry– Appropriate allowance for partial volume irradiation– Studies of prototype units

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BEAM PROFILEDiados readings at detector array entrance surface for each “retaining screw “level of detector housing. 16 second scan time.

Measure Position

Total Dose /scan (uGy)

Dose Rate (uGy/s)

Dose Rate Belconnen (uGy/s) 8/11/06

1 Top 129.8 8.11 6.2

2 175.3 10.96 15.4

3 185.6 11.6 17.4

4 264.3 16.52 22.3

5 326.1 20.38 24.8

6 359.1 22.44 24.85

7 Bottom 141 8.81 1.75

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BEAM QUALITY (HVL) Beam quality was assessed at two levels of the beam profile corresponding to

position 7 and position 5 in the above table.

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Anthropomorphic Dosimetry

• RANDO Phantom from Canberra Hospital RT.

• Luxel and TLD • Placed on surface and

in situ in organs

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Anthropomorphic Dosimetry

• Luxel– Calibration and read

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• TLD– Calibrated to150 kV

X-ray, Read at Canberra Hospital RT

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Anthropomorphic Dosimetry

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TLD Doses

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Male Effective Dose

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Female Effective Dose

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STUDY Effective Dose (uSv)

Ashtari and Buffa (Conpass) 2.2-2.3

Fong & Horrocks (Conpass Heathrow)

3-4 estimated

Koperski and Leslie 2.3Leslie and Munoz-Ferrada (OSL) with Rando

2.5

Leslie (TLD) with Rando 2.7-2.2ARS 3.3-5.2

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Comparative Doses

• Soter RS: 3 uSv• Chest X-ray 60 uSv• Abdomen X-ray 250 uSv• CT Chest and Abdo 10,000 uSv• Z-Backscatter security scan 0.1 uSv

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Regulatory Concerns

• Risk associated with an individual scan is negligible, however physical benefit to the scanned individual is NIL.

• Individual benefits:– Non-invasive cf pat down and body search– Modesty and dignity– Lower exposure than traditional forms of

radiographic investigation.

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Regulatory Concerns

• Social Benefits:– Security and safety– Control of contraband drugs, weapons,

environmental and economic threats.– Fast scan 16-18 sec

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Regulatory Concerns

• Indiscriminate use would result in a significant dose burden to certain individuals:– Frequent flyers– Community release or remand prisoners– Employment screens

• 200 scans (4 per week) would equate to half the public exposure limit (0.5 mSv)

• Training

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Training

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ACT Licence Conditions

• Use Licensing following training required– Radiation safety, operation, image interpretation.

• Maximum dose 0.25 mSv pa, adults only, consent and opt out provision.– Register of prisoner scans kept.

• QA phantom image developed, quarterly dose assessment

• Personal monitors and area monitors

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Acknowledgements

• Corporate Risk Solutions Pty Ltd– Project Funding

• ACT Dept of Corrections– Project Funding– Staff Alexander McConachie Correctional Centre and

Belconnen Remand Centre• Canberra Hospital Radiation Oncology

– TLD Calibration and Reads– RANDO anthropomorphic body phantom

• ACT Health Protection Service, Radiation Control Section.

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The End

• Thank you for your attention.

• Any questions please contact • Gammasonics Institute for Medical Research• 90 Queens Road, Five Dock NSW 2046• Tel : 029 713 1122 Fax : 029 713 1238• Website : www.gammasonics.com