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2 nd Annual ARDENT Workshop

2 nd Annual ARDENT Workshop. Quality assessment of hadrontherapy fields with TEPCs Paolo Colautti, INFN. 2 nd Annual ARDENT Workshop, Milano, 14-18 October 2013. The radiation quality concept .

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2 nd Annual ARDENT Workshop

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  1. 2ndAnnual ARDENT Workshop • Qualityassessment of hadrontherapy fieldswithTEPCs • Paolo Colautti, INFN 2nd Annual ARDENT Workshop, Milano, 14-18 October 2013

  2. The radiation quality concept The radiation field quality is meant as a physical measurable quantity, which is significant for primary effects on a biological system We define the measured y-spectrum in 1-2 µm sites as the radiation-field microdosimetric quality The couple of values and is a better quality mark of the radiation field. Some detectors measure only , which is used as quality mark of the radiation field. RBEµ, the microdosimetric assessment of RBE, can be an accurate quality mark for a given biological end-point. P.Colautti 2nd ARDENT workshop. Milano 14-18 October 2013

  3. Therapeutic beam constrains Fluence rates Proton continuos beam BNCT facility CNAO protons per spill CNAO carbon ions per spill 1 cm TEPC ought to measure at counting rates bigger than 106 s-1 1 mm TEPC will measure at counting rates bigger than 104 s-1 P.Colautti 2nd ARDENT workshop. Milano 14-18 October 2013

  4. Energy calibration technique in F ~ 1cm cylindrical TEPCs Tissue-equivalent conductive plastic Vacuum tide Al cylinder P.Colautti 2nd ARDENT workshop. Milano 14-18 October 2013

  5. Energy calibration technique in F ~ 1mm cylindrical TEPCs Cathode H.V. a-source Gas OUT a-source Guard tubes H.V. Gas IN Anode pulse P.Colautti 2nd ARDENT workshop. Milano 14-18 October 2013

  6. Measurements at the Nice therapeutic proton beam P.Colautti 2nd ARDENT workshop. Milano 14-18 October 2013

  7. Insulator surfaces damage without electric-field tubes 75 µm P.Colautti 2nd ARDENT workshop. Milano 14-18 October 2013

  8. 0.9 mm 0.150 mm 0.9 mm 0.200 mm Solution: a cavity inside the insulator to switch off the the electronic avalanche P.Colautti 2nd ARDENT workshop. Milano 14-18 October 2013

  9. Mini TEPC of 2.7 mm of external diameter P.Colautti 2nd ARDENT workshop. Milano 14-18 October 2013

  10. Vacuum and gas flow apparatus Pressure readout Turbo pump Membrane pump Exhaust Solenoid valve MFC MFC controller Gas P.Colautti 2nd ARDENT workshop. Milano 14-18 October 2013

  11. Electronic chain Low LET MCA Low LET amplifier Medium LET amplifier Medium LET MCA High LET amplifier High LET MCA +18/-6 volt HVanode Pulser HVcathode P.Colautti 2nd ARDENT workshop. Milano 14-18 October 2013

  12. Electronic chain P.Colautti 2nd ARDENT workshop. Milano 14-18 October 2013

  13. Before measuring: linearity checks Integral linearity High LET P.Colautti 2nd ARDENT workshop. Milano 14-18 October 2013

  14. Initial data from the 3 MCA P.Colautti 2nd ARDENT workshop. Milano 14-18 October 2013

  15. Volt calibration P.Colautti 2nd ARDENT workshop. Milano 14-18 October 2013

  16. Logaritmic compaction 1st 2nd Bth ….. ….. 1st log yi log yi+1 Equal log intervals Example: B = 60 First decade y1 = 1.0391, y2 = 1.0798, y3…. Δ1 = 0.04065 Second decade y1 = 10.0391, y2 = 10.0798, y3 …. Δ1 = 0.4065 Countdensity in compactedintervals Originalcounts P.Colautti 2nd ARDENT workshop. Milano 14-18 October 2013

  17. Sub-spectra junction Sub-spectra junction is not feasible if they do not superimpose P.Colautti 2nd ARDENT workshop. Milano 14-18 October 2013

  18. The pulse-height frequency distribution P.Colautti 2nd ARDENT workshop. Milano 14-18 October 2013

  19. The pulse-height weighted distribution P.Colautti 2nd ARDENT workshop. Milano 14-18 October 2013

  20. Lineal energy calibration ICRU 49 data 142 keV/µm Calibration factor: 142/475 = 0.299 P.Colautti 2nd ARDENT workshop. Milano 14-18 October 2013

  21. ∆E calculation in CSDA P.Colautti 2nd ARDENT workshop. Milano 14-18 October 2013

  22. Maximum ∆E-lost calculation in CSDA P.Colautti 2nd ARDENT workshop. Milano 14-18 October 2013

  23. Lineal-energy dose distribution Fractional part of the visual area is the fractional contribution to the the absorbed dose by the corresponding y-events Blue points are used to linearly extrapolate the frequency y-values down to 0.01 keV/µm P.Colautti 2nd ARDENT workshop. Milano 14-18 October 2013

  24. Weighting the dose distribution with a biological-significant function Fractional part of the visual area is the fractional contribution to the effective-dose of corresponding y-events The weight is 1for y-values < 10 keV/µm The weight is < 1 for y-values ≈> 200 keV/µm P.Colautti 2nd ARDENT workshop. Milano 14-18 October 2013

  25. Splitting the dose spectrum in its neutron and gamma components P.Colautti 2nd ARDENT workshop. Milano 14-18 October 2013

  26. Quality of the conjunctive-melanoma proton-therapeutic beam P.Colautti 2nd ARDENT workshop. Milano 14-18 October 2013

  27. The therapeutic beam quality Isoeffective-dose map Iso dose map Iso RBEµ map P.Colautti 2nd ARDENT workshop. Milano 14-18 October 2013

  28. Two mini TEPCs for quality measurements of BNCT radiation fields P.Colautti 2nd ARDENT workshop. Milano 14-18 October 2013

  29. The twin TEPC for BNCT P.Colautti 2nd ARDENT workshop. Milano 14-18 October 2013

  30. BNCT dose components twin TEPC measurements 30

  31. Suggested lectures • Glenn F.Knoll. Radiation Detection and Measurements. John Wiley & Sons, NY, 1979 • ICRU Report 36. Microdosimetry. 1983 P.Colautti 2nd ARDENT workshop. Milano 14-18 October 2013

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