Medical Radiology and Radiation Safety. 2019. Vol. 64. No. 4. P. 56–63

DOI: 10.12737/article_5d1b46c9133942.84705406

Е.S. Sukhikh^1,2, L.G. Sukhikh², E.L. Malikov², P.V. Izhevsky³, I.N. Sheino³, A.V. Vertinsky^1,2, A.A. Baulin^2,4

Uncertainty of Measurement Absorbed Dose by Gafchromic EBT3 Dosimeter for Clinical Electron and Photon Beams of Medical Accelerators

1. Tomsk Regional Oncology Centre, Tomsk, Russia. E-mail: This email address is being protected from spambots. You need JavaScript enabled to view it. ;
2. National Research Tomsk Polytechnic University, Tomsk, Russia;
3. A.I. Burnasyan Federal Medical Biophysical Center, Moscow, Russia;
4. Gamma Clinic High-Precision Radiology Centre (Gamma Medtechnology Ltd)., Obninsk, Russia

Е.S. Sukhikh – Head of Department, Assistant Professor, PhD Phys.-Math., Member of ESTRO, Member of EFOMP, Member of ISRS;
L.G. Sukhikh – Director of Research School of Physics, Dr. Sci. Phys-Math.;
E.L. Malikov – Researcher;
P.V. Izhevsky – Leading Researcher, Assistant Professor, PhD Med.;
I.N. Sheino – Head of the Lab., PhD Phys-Math.;
A.V. Vertinsky – Medical Physicist, PhD student;
A.A. Baulin – Medical Physicist, PhD student, Member of ISRS

Abstract

Purpose: Investigation of the relative errors of absorbed dose measurement based on polymer films Gafchromic EBT3 for clinical electron and photon beams of medical accelerators.

Material and methods: Polymer Gafchromic EBT3 films were calibrated using different radiation beams, namely photon and electron beams of Elekta Axesse medical accelerator with beam energy equal to 10 MV and 10 MeV, correspondingly, and electron beam of a betatron for intraoperative radiotherapy with beam energy equal to 6 MeV. The film pieces were irradiated by the uniform dose field in the dose range from 0.5 to 40 Gy. The dose value was controlled by cylindrical ionization chamber on Elekta Axesse accelerator and by the Markus parallel-plate ionization chamber on betatron. The irradiated films were scanned using Epson Perfection V750 Pro flatbed scanner in 16 bit RGB color mode with 150 dpi resolution. The red and green channels were used for further analysis. The central part of each film was used for calculation of average values of net optical density and its root-mean-square. As a result, the calibration curves, i.e. dependence on the reference absorbed dose measured by ionization chamber on the net optical density were constructed taking into account uncertainties of dose measurement and optical density measurement.

Results: The relative uncertainty for the dose measurement lies within 7 % for low doses (less than 1 Gy) and within 4 % for higher doses. The green channel is less sensitive to the radiation, but its relative uncertainty values are in general 1–2 % lower than the ones for the red channel. The use of different calibration sources results in different calibration curves with difference up to ± 6 % for the green channel.

Conclusion: The polymer Gafchromic EBT3 films can be used for absorbed dose measurement for the doses not less than 0.5 Gy. For lower dose values the dose measurement uncertainty caused by statistical reasons amounts 15 %. For dose values of about 1 Gy and higher the dose measurement uncertainty amounts 5 % that allows to use the films for transverse and longitudinal prescription treatment dose distribution measurement with very high spatial resolution.

Key words: radiation therapy, Gafchromic EBT3 film, clinical dosimetry, medical accelerators, absorbed dose, uncertainties

REFERENCES

1. Syed YA, Petel-Yadav AK, Rivers C, Singh AK. Stereotactic radiotherapy for prostate cancer: A review and future directions. World J Clin Oncol. 2017;8(5):389-97. DOI: 10.5306/wjco.v8.i5.389.
2. Diot Q, Kavanagh B, Timmerman R, Miften M. Biological-based optimization and volumetric modulated arc therapy delivery for stereotactic body radiation therapy. Med Phys. 2012;39(1):237-45. DOI: 10.1118/1.3668059.
3. Fiorentino A, Giaj-Levra N, Tebano U, et al. Stereotactic ablative radiation therapy for brain metastases with volumetric modulated arc therapy and flattening filter free delivery: feasibility and early clinical results. Radiol Med. 2017;122(9):676-82. DOI: 10.1007/s11547-017-0768-0.
4. Gafchromic. Gafchromic EBT3 film specifications. [Internet]. 2017 [cited 2019 Feb. 20]. Available from: http://www.gafchromic.com/documents/EBT3_Specifications.pdf.
5. Andreo P, Burns D, Hohlfeld K, et al. Absorbed dose determination in external beam radiotherapy: An international code of practice for dosimetry based on standards of absorbed dose to water. Technical Report Series no. 398. IAEA. 2000:251.
6. Almond P, Biggs P, Coursey B, et al. AAPM’s TG-51 protocol for clinical reference dosimetry of high-energy photon and electron beams. Med. Phys. 1999;26(9):1847-70.
7. Sorriaux J, Kacperek A, Rossomme S, et al. Evaluation of gafchromic ebt3 films characteristics in therapy photon, electron and proton beams. Physica Medica. 2013;29.Suppl.6:599-606. DOI: 10.1016/j.ejmp.2012.10.001.
8. Hartmann B. Martisikova M, Jakel O. Technical note: Homogeneity of Gafchromic EBT2 film. Med Phys. 2010;37.Suppl.4:1753-6. DOI: 10.1118/1.3368601.
9. Niewald M, Fleckenstein J, Licht N, et al. Intraoperative radiotherapy (IORT) combined with external beam radiotherapy (EBRT) for soft-tissue sarcomas – a retrospective evaluation of the homburg experience in the years 1995-2007. Radiat Oncol. 2009;4. Suppl.32:1-6. DOI: 10.1186/1748-717X-4-32.
10. Niroomand-Rad A, Blackwell C, Coursey B, et al. Radiochromic film dosimetry: Recommendations of AAPM radiation therapy committee task group 55. Med Phys. 1998;25. Suppl.11:2093-115. DOI: 10.1118/1.598407.
11. Devic S, Seuntjens J, Hegyi G, et al. Dosimetric properties of improved gafchromic films for seven dierent digitizers. Med Phys. 2004;31. Suppl.9:2392-401. DOI: 10.1118/1.1776691.
12. Butson M, Yu P, Cheung T, Alnawaf H. Energy response of the new EBT2 radiochromic film to x-ray radiation. Radiat Measur. 2010;45. Suppl.7:836-9. DOI: 10.1016/j.radmeas.2010.02.016.
13. Micke A, Lewis D, Yu X. Multichannel film dosimetry with nonuniformity correction. Med Phys. 2011;38. Suppl.5:2523-34. DOI: 10.1118/1.3576105.
14. Devic S. Radiochromic film dosimetry: Past, present, and future. Physica Medica. 2011;27. Suppl.3:122-34. DOI: 10.1016/j.ejmp.2010.10.001.
15. Soares C. Radiochromic film dosimetry. Radiat Measur. 2006;41. Suppl.1:S100-S116.
16. Reinhardt S, Hillbrand M, Wilkens J, Assmann W. Comparison of gafchromic EBT2 and EBT3 films for clinical photon and proton beams. Med Phys. 2012;39 Suppl.8:5257-62. DOI: 10.1118/1.4737890.
17. Wolfram. [Internet]. 2019. [cited 2019, Feb. 20]. Available from: https://www.wolfram.com/mathematica.
18. IBA. Description of dosimetric system iba matrix. [Internet]. 2019. [cited 2019, Feb. 20]. Available from: http://www.iba-dosimetry.com/complete-solutions/radiotherapy/imrt-igrt-rotational-qa/matrixxes.
19. IBA, Description of clinical dosimeter dose-1. [Internet]. 2017. [cited 2019, Feb. 20]. Available from: http://www.iba-dosimetry.com/sites/default/files/resources/RT-BR-E-DOSE1_Rev.1_0211_0.pdf.
20. PTW, Description of dosimeter ptw unidos E. [Internet]. 2017. [cited 2019, February 20]. Available from: http://www.ptw.de/unidos_e_dosemeter_ad0.html.
21. PTW, Description of electron cionization chamber PTW23343. [Internet]. 2017. [cited 2019, Feb. 20]. Available from: http://www.ptw.de/advanced_markus_electron_chamber.html.
22. PTW, Description of solid state phantom ptw rw3 SLAP phantom T29672. [Internet] 2017. [cited 2019, February 20]. Available from: http://www.ptw.de/acrylic_and_rw3_slab_phantoms0.html.
23. Epson, Technical characteristics of EPSON Perfection V750 scanner. [Internet]. 2017. [cited 2019, Feb. 20]. Available from: http://epson.ru/catalog/scanners/epson-perfection-v750-pro/?page=characteristics.

For citation: Sukhikh ЕS, Sukhikh LG, Malikov EL, Izhevsky PV, Sheino IN, Vertinsky AV, Baulin AA. Uncertainty of Measurement Absorbed Dose by Gafchromic EBT3 Dosimeter for Clinical Electron and Photon Beams of Medical Accelerators. Medical Radiology and Radiation Safety. 2019;64(4):56–63. (English and Russian).

DOI: 10.12737/article_5d1b46c9133942.84705406

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