This document summarizes a study on the radiation dose assessment of a security screening device called the Soter RS. It finds that the effective radiation dose per scan is approximately 3 microsieverts, which is much lower than other medical imaging techniques like chest x-rays. While the risk to any individual is low, frequent or indiscriminate use could result in unnecessary radiation exposure. Proper training and regulatory controls are needed to ensure safe operation and optimize the security benefits versus radiation risks.

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Radiation Dose Assessment of
Persons Undergoing the Soter RS
Security Screening
David Leslie BHSc, Dip.Med Rad, MIR
Manager Compliance and Consulting
Gammasonics 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 PROFILE
Diados 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 2.3
Leslie and Munoz-Ferrada (OSL)
with Rando
2.5
Leslie (TLD) with Rando 2.7-2.2
ARS 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