Interpretation of measured dose data in x ray imaging
This presentation is the property of its rightful owner.
Sponsored Links
1 / 9

Interpretation of measured dose data in X-ray imaging PowerPoint PPT Presentation


  • 88 Views
  • Uploaded on
  • Presentation posted in: General

Interpretation of measured dose data in X-ray imaging. IRPA 14.-18.5.2012 Glasgow, UK. Paula Toroi PhD, Senior scientist STUK-Radiation and Nuclear Safety Authority, Finland [email protected] Quantities. Measurable quantity Air kerma based technical parameter Not a patient dose

Download Presentation

Interpretation of measured dose data in X-ray imaging

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Interpretation of measured dose data in x ray imaging

Interpretation of measured dose data in X-ray imaging

IRPA14.-18.5.2012

Glasgow, UK

Paula Toroi

PhD, Senior scientist

STUK-Radiation and Nuclear Safety Authority, Finland

[email protected]

Paula Toroi


Quantities

Quantities

  • Measurable quantity

    • Air kerma based technical parameter

    • Not a patient dose

  • Organ or tissue dose

    • A base for risk estimates (ICRP 103, 2007)

Effective dose

  • Generally known and used quantity

  • One simple combined risk quantity

  • Not for individuals

Statisticalriskmodels

  • For selected organs

  • BEIR VII, 2006

Paula Toroi


Methods for patient dose estimation

Methods for patient dose estimation

  • Use of tabulated doses

    • Averaged values for some clinical practice

    • E.g. Effective dose = 0.02 mSv (thorax)

    • Uncertainty for general use is high

  • Conversion from measured value

    Organ dose or effective dose=

    Measurable quantity* Conversion factor

    • E.g. Conversion factor = 0.25 mSv/mGy (thorax)

    • What is the uncertainty of a conversion?

Paula Toroi


Influence parameters for conversion

Influence parameters for conversion

Beam properties:

  • Beam geometry

    • Size, shape, location

  • Radiation quality

    • Radiation spectrum

      (tube voltage, filtration)

      Patient properties:

  • Body: size, shape, anatomy

  • Organ: size, shape, location

Paula Toroi


Tabulated conversion factors

Tabulated conversion factors

Beam properties:

  • for specified examination

  • some times for different radiation qualities

    Patient properties:

  • normally for standard size patient model

EC, 2008 RP N° 154

Paula Toroi


Beam properties radiation quality

Beam properties: radiation quality

130%

Paula Toroi

Monte Carlo simulations are made with PCXMC (STUK, Finland)


Patient properties

Patient properties

Paula Toroi

Monte Carlo simulations are made with ImpactMC (CT-imaging, Germany)


Main uncertainties in the conversion

Main uncertainties in the conversion

  • Radiation quality (RQ)

    • It is very important to choose a correct factor

  • Patient properties

    • Large differences between individuals

    • Correction factors available for CT

      (AAPM 204, 2011)

      What is the uncertainty of risk estimation?

Paula Toroi


Interpretation of measured dose data in x ray imaging

Thank you!

Acknowledgements:

*IAEA collaborative research project E2.10.008. The development of advanced dosimetry techniques for diagnostic and interventional radiology.

*Colleagues from STUK: Anna Kelaranta, Markku Tapiovaara, Teemu Siiskonen and Antti Kosunen

Paula Toroi


  • Login