1 / 18

Object: Calibration of Gafchromic EBT3 [1,2 ] Motivation :

Characterization of GafChromic EBT3 films with 60 CO and low energy protons for radiobiology dosimetry.

elyse
Download Presentation

Object: Calibration of Gafchromic EBT3 [1,2 ] Motivation :

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. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Characterization of GafChromic EBT3 films with 60CO and low energy protons for radiobiology dosimetry F. Ambrosinib, R. Cherubinic, C. De Angelisd, G. Espositod, F. Marracinoa, L. Picardia, M. Pimpinellae, C. Ronsivallea, C. Snelsf, M. A. Tabocchinid, M. Vadruccia a: ENEA C.R. Frascati, UT. APRAD RadiationSourcesLaboratory, Via E. Fermi, 45, 00044, Frascati (RM), Italy b: Sapienza Università di Roma - DIET, via Eudossiana, 18, 00184, Roma, Italy c: INFN-Laboratori Nazionali di Legnaro Viale dell'Università 2, 35020 Legnaro (PD), Italy d: Istituto Superiore di Sanità - Technology and HealthDepartment, Viale Regina Elena 299, 00161 Roma, Italy e: ENEA C. R. Casaccia Istituto Nazionale di Metrologia delle Radiazioni Ionizzanti Via Anguillarese, 301 00123 Roma Italy f: ENEA C.R. Casaccia, UT. BIORAD Radiobiology, Via Anguillarese, 301, 00123, Roma, Italy Biophysics@Rome Conference May22-23 2014

  2. Characterization of GafChromic EBT3 films with 60CO and low energy protons for radiobiology dosimetry Object: Calibration of Gafchromic EBT3 [1,2] Motivation: Gafchromic EBT3, willbe usedfor radiobiologyexperiments with V79 cells in the framework of the TOP-IMPLART Project (protonfacilityunder constructionat ENEA c.r. Frascati). Methods: Construction of calibration curves Radiation doses vs optical densities (calculated from measured intensity of film darkening) with twodifferenttype of radiation: photon and proton.

  3. Characterization of GafChromic EBT3 films with 60CO and low energy protons for radiobiology dosimetry Materials: Gafchromic EBT3:self-developing dosimetry film (8”x10”) range of sensitivity 0.01 to > 40 Gy ConfigurationComposition Photonsprimary standard of adsorbed dose to water for 60Co Rays Italian National Metrology Institute for Ionizing Radiation quantities of ENEA (ENEA-INMRI) Protonslowenergyprotonbeam from INFN-LNL CN 7MV VdGaccelerator

  4. Characterization of GafChromic EBT3 films with 60CO and low energy protons for radiobiology dosimetry Calibration of Gafchromic EBT3 with the primary standard of adsorbed dose to water for 60Co rays Based on a graphite calorimeter measurements [3]. Dose rate was measured with a FARMER NE2571 ionization chamber calibrated in water using graphite calorimeter measurements for dose absolute measurements. 60Co  source Gamma emissions 1,17 and 1,33 MeV Water phantom with FARMER NE2571 ionization chamber Housing in PMMA of FARMER NE2571 ionization chamber

  5. Characterization of GafChromic EBT3 films with 60CO and low energy protons for radiobiology dosimetry Measurements in a PMMA phantom (25.225.225.2 cm3)equivalent to a water phantom 303030 cm3 Housing of EBT3 holder EBT3 (3x3 cm2) holder in PMMA EBT3 holder is positioned 2.66 cm from the surface of the PMMA phantom in front of the source of 60Co , 2.66 cm corresponds to 3.2 cm in water whichcorresponds the reference calculation of the dose: 99% beam uniformity at 100 cm from the source

  6. Characterization of GafChromic EBT3 films with 60CO and low energy protons for radiobiology dosimetry Dose rate calculation is corrected for the decay T1/2=5.27 y and for the end error (ex: delay for door opening Pb lockbox, movementof the source): 4,33 10-3Gy/s at the time of measurement EBT3 sample (3x3 cm2) cut out from the same foil. Irradiated at doses: 0.5, 1, 3, 5, 8, 10, 20, 30 Gy Images of irradiatedfilms: - scanned with Epson Expression 11000XL - analyzed with Picodose software (Redchannelbecause EBT3 are more sensible) - meanvalue of Intensity and standard deviation are read inside a ROI - Sameresaults are obtained with Image J analysissoftware Epson Expression 11000 XL Picodose X Pro

  7. Characterization of GafChromic EBT3 films with 60CO and low energy protons for radiobiology dosimetry Calibration curve from fit of experimental dataDose vs Intensity EBT3 60Co D= a × exp(b × Iexp) Iexp= intensity for exposed film Coefficients (with 95% confidence bounds): a= 6710 (6188, 7232) b= -0.000136 (-0.0001437, -0.0001283) R2= 0.9931 errorbars= standard deviation Dose uncertainty= 1% Intensityuncertainty= standard deviationinside ROI

  8. Characterization of GafChromic EBT3 films with 60CO and low energy dosimetry

  9. Characterization of GafChromic EBT3 films with 60CO and low energy dosimetry Calibration of Gafchromic EBT3 lowenergyproton (5 MeV) beam from INFN-LNL CN 7MV VdGaccelerator[5] Schematic view of the proton irradiation facility

  10. Characterization of GafChromic EBT3 films with 60CO and low energy dosimetry Calibration of Gafchromic EBT3 lowenergyproton (5 MeV) beam from INFN-LNL CN 7MV VdGaccelerator[5] Schematic view of the proton irradiation facility

  11. Characterization of GafChromic EBT3 films with 60CO and low energy dosimetry Calibration of Gafchromic EBT3 lowenergyproton (5 MeV) beam from INFN-LNL CN 7MV VdGaccelerator[5] Schematic view of the proton irradiation facility Circularsamplesholder Exit beam line vacuum 10-6mbar

  12. Characterization of GafChromic EBT3 films with 60CO and low energy dosimetry -Two Au scattering foils of 1 m make the beam homogeneous on a circular surface with a diameter of at least 13 mm in air at 1 cm distance from the window / vacuum. -EBT3: circular shape with a diameter of 16 mm, inserted, together with a sheet of mylar 50 µm thick, in a cylindrical steel sample holder which exposes an area of ​​13 mm diameter: It is chosen to use such a configuration sample holder and mylar layer, since the experiments will occur precisely with such a set-up: the V79 cells will have as growth substrate a film of mylar 50 µm. Circularsamplesholder cylinders steel sample holder

  13. Characterization of GafChromic EBT3 films with 60CO and low energy dosimetry -Center of circularsamplesholderisfixed on a sledge in axis with the particle beam. By controlling rotation of the holder is possible to irradiate samples in groups of 10 with the same setting of extraction of protons (5 MeV) from the accelerator. - Proton beam extracted from the accelerator is controlled through a current reading and through a semiconductor detector (silicon manufactured by Ortec 500 m thick) Si detector for fluence F (cm-2) measurements D= 1,6*10-9  LET(keV/µm)  F (cm-2) 5 cm

  14. Characterization of GafChromic EBT3 films with 60CO and low energy dosimetry - EBT3 sample (Ø 13 mm) cut out from the same foil. Irradiated at doses:0.5, 1, 3, 3.5, 4.5, 5, 8, 10, 20, 30 Gy. Dose rate 2.1 Gy/min - Same analysis of the films made ​​for the 60Co  (see slide 5) Calibration curve from fit of experimental dataDose vs Intensity D= a × exp(b × Iexp) Iexp= intensity for exposed film Coefficients (with 95% confidence bounds): a= 7679(7131, 8227) b= -0.0001311 (-0.0001377, -0.0001245) R2=0.9922 errorbars= standard deviation Dose uncertainty= 5% Intensityuncertainty= standard deviationinside ROI

  15. Characterization of GafChromic EBT3 films with 60CO and low energy dosimetry

  16. Characterization of GafChromic EBT3 films with 60CO and low energy dosimetry Calibration of EBT3: comparison 60Co and protons Clear difference in response of the films EBT3 to the two types of radiation: in particular for the same dose the optical density read following a proton irradiation is lower (viceversafor the intensity of blackening), approximately 14 %, to those relating to radiation with photons.

  17. Characterization of GafChromic EBT3 films with 60CO and low energy protons for radiobiology dosimetry TOP-IMPLART: Oncological Therapy with Protons – Intensity Modulated Proton Linear Accelerator for RadioTherapyset up ( ENEA Frascati) and V79 irradiation accelerator is composed by a sequence of linear sections: -one is a 7 MeV proton linac -other segments will reach 150 MeV. low energy part is used as a facility for radiobiology experiments with a vertical and horizontal beam Sample Holder Bending Magnet Vertical line

  18. Characterization of GafChromic EBT3 films with 60CO and low energy protons for radiobiology dosimetry Conclusion Calibration of EBT3 with 60Co  and proton beams of energy 5MeV: were constructed calibration curves vs dose and dose intensity of the red channel vs. netOD, in the dose range from 0.5 Gy to 30 Gy. The comparison of these curves with those built for the calibration of the films with bundles of 60Co  showed that for the same dose response of the EBT3 irradiated with protons has an intensity in the red channel that is highest and a lowest blackening, viceversafor the optical density, compared to irradiation with photons. [1] “GAFCHROMIC EBT3 Scan Handling Guide”, TecnologieAvanzate [2] Sorriaux, J. et al. Evaluation of Gafchromic EBT3 films characteristics in therapy photon, electron and proton beams. 2013, PhysicaMedica 29, 599-606. [3] Guerra AS, Laitano RF, Pimpinella M. Characteristics of the adsorbed dose to water standard at ENEA. Phys. Med. Biol. 41 (1996) 657-674. [4] Devic S. et al. Dosimetricproperties of improved GafChromic films for seven different digitizers.Med Phys 2004;31:2392-401. [5] Belli M. et al. Proton irradiation facility for radiobiological studies at a 7 MV Van DE Graaff accelerator.Nuclear Instruments and Methods in Physics Research A256 (1987) 576-580

More Related