Dosimetric evaluation of electron beam Monte Carlo isodoses distribution based on thermoluminescent dosimetry

Flavia dos Reis Gonçalves; Elizabeth Vianello; Claudio Viegas; Alfredo Viamonte

doi:10.15392/bjrs.v8i1.1108

Authors

Flavia dos Reis Gonçalves Instituto Nacional de Cancer
Elizabeth Vianello
Claudio Viegas
Alfredo Viamonte

DOI:

https://doi.org/10.15392/bjrs.v8i1.1108

Keywords:

Electron dosimetry, Monte Carlo, TLD

Abstract

Electron beams are applied in radiotherapy treatments where superficialized doses are desirable as well as deeper tissues sparing. Monte Carlo method has been recently implemented in the TPS as the algorithm for electron beam isodoses calculation at the National Institute of Cancer in Brazil. This work comprises an additional method of evaluation of the isodoses generated by the TPS, considering the irradiation of a non-flat surface. A 6-Gy electron beam breast irradiation was planned and delivered to an anthropomorphic phantom into which 36 capsules with TLD100 were inserted. The TLD calibration curve was performed from 100 cGy to 700 cGy. In an overall analysis, eMC algorithm isodose distribution results agreed with TLD measured doses. 75% of measured data met the 5% accuracy criteria, which can be considered in good agreement with the recommended uncertainties involved in a radiotherapy treatment. Considered all collected data, 8 TLDs received extremely low doses and due to tissue attenuation of the electron beam, the TLD measurements might have additional uncertainties. If these data are not taken into account, 100% of the measured doses, considering the uncertainties, meet the 5% accuracy criteria. About the 3 methods for isodose smoothing available in the eMC algorithm, the low level of dose smoothing option provides the best matching with measured data, consisting of the most reliable option. Considering the AAPM recommendations eMC algorithm offers an accurate solution for isodoses calculation, within a 5% accuracy.

Views: 111
PDF Downloads: 108

Downloads

Download data is not yet available.

References

Zhang A, Wen N, Nurushev T, Burmeister J, Chetty IJ. Comprehensive evaluation and clinical implementation of commercially available Monte Carlo dose calculation algorithm. J Appl Clin Med Phys.14(2):127–45, 2013.

Cygler JE, Battista JJ, Scrimger JW, Mah E, Antolak J. Electron dose distributions in experimental phantoms: a comparison with 2D pencil beam calculations. Phys Med Biol. 32(9):1073–86, 1987.

Varian Medical Systems, Inc. Eclipse Photon and Electron Algorithms Reference Guide. Palo Alto, CA, United States of America, 2016.

Ding GX, Duggan DM, Coffey CW, Shokrani P, Cygler JE. First macro Monte Carlo based commercial dose calculation module for electron beam treatment planning—new issues for clinical consideration. Phys Med Biol. 51(11): 2781–99, 2006.

Lawrence SL, van Lieshout NHM, Charland PM. Assessment of Eclipse electron Monte Carlo output prediction for various topologies. J Appl Clin Med Phys.16(3): 99-106, 2015.

Robar V, Zankowski C, Pla MO, Podgorsak, EB. Thermoluminescent dosimetry in electron beams: Energy dependence. Med Phys 23, 667-73, 1996.

Instituto Nacional de Câncer José Alencar Gomes da Silva. Relatório-Resumo do Serviço de Qualidade em Radiações Ionizantes 2009-2010. INCA: Rio de Janeiro, 2012.

Viegas CBB. Dosimetria In Vivo Com Uso De Detectores Semicondutores E Termoluminescentes Aplicada Ao Tratamento De Câncer De Cabeça E Pescoço. Thesis. Universidade Federal do Rio de Janeiro, 2003.

Holt JG, Edelstein GR, Clark TE. Energy Dependence of the Response of lithium fluoride TLD rods in high energy electron fields. Phys Med Biol 20, 559-570, 1975.

Carver RL, Hogstrom KR, Chu C, Fields RS, Sprunger CP. Accuracy of pencil-beam redefinition algorithm dose calculations in patient-like cylindrical phantoms for bolus electron conformal therapy. Med Phys 40 (7), 071720:1-11, 2013.

Carver RL, Sprunger CP, Hogstrom KR, Popple RA, Antolak JA. Evaluation of the Eclipse eMC algorithm for bolus electron conformal therapy using a standard verification dataset. J Appl Clin Med Phys.17(3): 52-60, 2016.

Boyd RA, Hogstrom KR, Antolak JA, Shiu AS. A measured data set for evaluating electron-beam dose algorithms. Med Phys.28(6): 950-958, 2001.

Smilowitz JB, Das IJ, Feygelman V, Fraass BA, Kry SF, Marshall IR, Mihailidis DN, Ouhib Z, Ritter T, Snyder MG, Fairobent L. AAPM Medical Physics Practice Guideline 5.a.: Commissioning and QA of Treatment Planning Dose Calculations — Megavoltage Photon and Electron Beams. J Appl Clin Med Phys. 16(5):14-34, 2015.

IAEA TRS-398. Absorbed Dose Determination in External Beam Radiotherapy: An International Code of Practice for Dosimetry based on Standards of Absorbed Dose to Water. 2006.