Two-Dimensional Thermoluminescence Dosimetry System … Gajewski.pdfTwo-Dimensional...

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Two-Dimensional Thermoluminescence Dosimetry System for Proton Beam Quality Assurance Jan Gajewski Institute of Nuclear Physics, Kraków, Poland German Cancer Research Center, Heidelberg, Germany

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  • Two-Dimensional Thermoluminescence Dosimetry

    System for Proton Beam Quality Assurance

    Jan GajewskiInstitute of Nuclear Physics, Kraków, PolandGerman Cancer Research Center, Heidelberg, Germany

  • Existing methods used in dosimetryJan Gajewski IFJ PAN / DKFZ

    TL pellet diamond OSL ionization

    chamber semiconductor

    diode

    Films • Gafchromic• Radiographic

    TLD foils matrix of ionisation

    chambers strip and pixel

    semiconductor detectors

    Fricke gel 3-D scintillators

    TLD personal badge

    1-dimensional 2-dimensional 3-dimensional

    Strip semiconductor detector 3-D Scintillator

    2D TLD for proton beam QA

  • Presentation plan

    • Principle of operation• 2D Thermoluminescence System

    • TL Foils• Readers• Dosimetric properties

    • 2D TL system for broad beam Quality Assurance• TL foils and LET-painting technique• Summary and plans for future

    2D TLD for proton beam QAJan Gajewski IFJ PAN / DKFZ

  • The principle of 2-D TL Dosimetry

    Preparation of foil

    Irradiation

    Heating

    Collection of emitted light

    Data analysis

    2D TLD for proton beam QAJan Gajewski IFJ PAN / DKFZ

  • • Water resistance and flexibility• Up to 20 x 20 cm2

    • Reusability• Resolution below 0.1 mm2

    • Linearity of dose response: 0.05-20 Gy

    Dosimetric system – TLD foils2D TLD for proton beam QA

    MPC-2D CaSO4Zeff 8.1 13.4

    Two types of foils:• LiF:Mg,Cu,P (MCP-2D)• CaSO4:Dy

    Jan Gajewski IFJ PAN / DKFZ

  • Laboratory Reader:• detector size

    50 x 50 mm2

    • resolution 640 x 480 px2

    • fully adjustable

    Clinical Reader:• detector size 200 x 200 mm2

    • resolution 1024 x 1024 px2

    • easy and safe to use

    Laboratory reader

    Clinical reader

    Dosimetric system – hardware2D TLD for proton beam QAJan Gajewski IFJ PAN / DKFZ

  • Dosimetric properties – uniformity

    After corrections the uniformity of readouts is around 2%

    20 cm

    2D TLD for proton beam QAJan Gajewski IFJ PAN / DKFZ

  • Dosimetric properties – dose responseLinearity Index was constant within ±5% measured with the Laboratory Reader. For the Clinical Reader it is ±2%

    Laboratory Reader

    Clinical Reader

    ±2%

    2D TLD for proton beam QA

    f(D)Df(D)

    f(D)D

    f(D)D

    Jan Gajewski IFJ PAN / DKFZ

  • Dosimetric properties – Reproducibility

    Repeatability was found below 2%

    More than 20 equivalent irradiations and readouts

    For previous reader and software it was 5%

    For radiochromic films it is 1-6%[1] McLaughlin et al. Methods Phys. Res. A 302[2] N. V. Klassen et al. Med. Phys. 24

    2D TLD for proton beam QAJan Gajewski IFJ PAN / DKFZ

  • Beam cross-section in PMMA phantom

    Irradiations have been performed with 60 MeV proton beam at IFJ PAN in Kraków (AIC-144 cyclotron)

    DiodeTLD

    2D TLD for proton beam QAJan Gajewski IFJ PAN / DKFZ

  • Profile of proton beam – PBP

    Beam

    25 mm collimator PMMA plates TLD foil

    Experimental setup Pristine Bragg Peak

    2D TLD for proton beam QAJan Gajewski IFJ PAN / DKFZ

  • Profile of proton beam – SOBP

    Beam

    25 mm collimatorPMMA plates TLD foilSOBP

    wheel

    Spread Out Bragg PeakExperimental setup

    2D TLD for proton beam QAJan Gajewski IFJ PAN / DKFZ

  • Profile of proton beam – summary

    3D visualisation of a cross-section of a proton broad beam

    • About 100 beam cross-sections have been measured• Dose profiles of beam measured with TL foils and

    photodiode are comparable• Measured flatness of dose profiles is in 5-12% range

    (for diode it is 2-3%)• Penumbra is broader with deeper location in phantom

    (difficult to measure with diode)• Experiments conducted at IFJ PAN

    in Kraków show that 2D TLD system is a good tool for proton beam Quality Assurance

    2D TLD for proton beam QAJan Gajewski IFJ PAN / DKFZ

  • MCP-2D relative efficiency – η

    TL response depends not only on dose but also on ionization density.

    2D TLD for proton beam QAJan Gajewski IFJ PAN / DKFZ

  • LET-painting with TL foils

    Difference in relative efficiency

    Set of two foils: MCP-2D + CaSO4:Dy

    Energy response for CaSO4:Dy foils needs to be verified

    Biological response depends on ionisation density. Determination of LET is very important for ion radiotherapy.

    The idea

    Beam

    CaSO4:DyMCP-2D

    2D TLD for proton beam QAJan Gajewski IFJ PAN / DKFZ

  • Plans for future• Incoming experiments (HIT-Heidelberg)

    – Energy response for 12C and p+ ions– Tests of QA of scanning beam– Calibration curve for dose/LET dosimetry– Validation of the dose/LET response in clinical

    conditions– Other TL foils properties: transparency, angular

    response, fading, etc.• 2D TLD system will be used for QA of therapeutic

    scanning beam at Bronowice Cyclotron Center in Kraków (C-235 IBA cyclotron)

    2D TLD for proton beam QAJan Gajewski IFJ PAN / DKFZ

  • Thank You for Your attention

    Jan Gajewski IFJ PAN / DKFZ

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