Journal of Nuclear Science, Engineering and Technology (JONSAT)
In cooperation with the Iranian Nuclear Society

Designing and Evaluating a Simple Small Phantom for Dosimetry Intercomparison of Iinacs Photon Beams

Document Type : Research Paper

Authors

M Beigi
B Hashemi
M Allahverdi
S.R Mahdavi
H Ghiasi
Abstract
This paper evaluate the functionality of a designed small phantom for determining the accuracy and performance of megavoltage radiotherapy machines through an external quality audit. The small phantom was designed to check the photon beams at the reference and some non-reference conditions on a linac at two radiotherapy centers in Tehran. LiF TLDs were used for experimental dosimetry. A standard phantom with an ionization chamber and the Monte Carlo code were used to calculate the conversion factor of the doses in the small phantom to the conventional condition. The result of this study showed that the dose conversion factors derived from the measurements made in the designed and standard phantoms are in good agreement with those calculated from the MCNPX simulations. At the reference condition, the amount of difference between the simulation and measurement were 0.5 at 6 and 18 MV. The differences for the 7cm×7cm field were 0.2% and 0.3% respectively, while for the 20cm×20cm field were 0.1% and 0.6%, respectively for the above energy. Using the designed phantom, two similar Varian linacs were checked at the reference conditions and amounts of their deviation between the planned and measured doses were estimated. The amount of variations of the phantom dose conversion factor with the field size indicates that the small designed phantom is not only appropriate for the small field sizes but also for the large ones. The results confirmed the functionality of the designed simple phantom with TLDs as an appropriate mailing system to carry out dosimetric intercomparison among different radiotherapy centers.

Highlights

 

 

  1. Martin CJ and Sutton DG, “Practical radiation protection in healthcare,” New York, Oxfor University Press Inc (2003).

     

  2. Intenational Atomic Energy Agency, “Quality assurance in radiotherapy,” Vienna, IAEA (1997).

 

  1. Intenational Atomic Energy Agency. “Comprehensive QA for radiation oncology,” American Association of Physicisits in Medicin. Vienna, IAEA (1994).

 

  1. Hoornaert MTh VDJ, Vynckier S, Bouiller A, “A dosimetric quality audit of photon beams by the Belgian Physicist Association,” Radiother Oncol, 28:37-43 (1993).

 

  1. Kalef-Ezra JA, Boziria A, Litsas J, Tsekeris P, Koligliatis T. “Thermoluminecense doimetry for quality assurance in radiation therapy,” Rad Prot Dos. 101:403-5 (2002).

 

  1. Podgorsak EB. “Radiation oncology physics: a handbook for teachers and student,” Vienna: IAEA (2005).

 

  1. MA EK, Harrison D, Cornes S J, Howlett DJ, Joseph T, Kron CS, Hamilton JW, Denham B. “Comprehensive Australasian multicentre dosimetric intercomparison,” Issues, logistics and recommendations. Med Imag & Rad Oncol, 53:119-131 (2009).

 

  1. Nisbet A TD, Sheridan ME, “A dosimetric intercomparison of kilovoltage X-rays, megavoltage photons and electrons in the Republic of Ireland,” Radiother Oncol, 48(1): 95-101 (1998).

 

  1. Nisbet A TD, “A dosimetric intercomparison of electron beams in UK radiotherapy centres,” Phys Med Biol, 42(12), 2393-409 (1997).

 

  1. Hansson U JK, “Quality audit of radiotherapy with EORTC mailed in water TL dosimetry,” Radiother Oncol. 20(3), 191-6 (1991).

 

  1. Davis B FP. “Quality audit of megavoltage radiotherapy units: intercomparison of dose at a reference point using mailed TL-dosimetry system,” Radiother Oncol, 28(1), 79-81 (1993).

 

  1. Dutreix A vdSE, Derreumaux S, Chavaudra J. “Preliminary results of a quality assurance network for radiotherapy centers in Euroupe,” Radiother Oncol, 29, 97-101 (1993).

 

  1. Huntley R IJ, “The 1998 Australian external beam radiotherapy survey and IAEA/WHO TLD postal quality audit,” Australas Phys Eng Sci Med. 23(1), 21-9 (2000).

 

  1. Aguirre JF TR, Ibbott G, Stovall M, Hanson, W, “Thermoluminescence dosimetry as a tool for the remot verification of output for radiotherapy beams: 25 years of experince,” In proceedings of the International Symposium on Standards and Codes of Practice in Medical Radiation Dosimetry IAEA, Vienna, IAEA (2002).

  2. J.H. Lee CYY, S.M. Hsu, M.Y. Shi, W.L. Chen, C.F. Wang, “Simple dose verification system for radiotherapy radiation,” Rad Meas. 43, 954-8 (2008).

 

  1. Arib M YA, Messadi A, Dari F. “Optimum parameters of TLD100 powder used for radiothrapy beams calibration check,” Med Dosim. 31, 4-9 (2006).

 

  1. Kroutilikova D NJ, Judas L. “Thermolumonescense dosimetrs(TLD) quality assurance network in the Czech Republic,” Radiother Oncol. 66, 35-44 (2003).

 

  1. Kron T HC, Roff M, Denham J, “Dosimetric intercomparison for two Australasian clinical trials using an anthropomorphic phantom,” IntRadiat Oncol Biol Phys. 52, 66-79 (2002).

 

  1. Kurt K MVK, McKeever S. W. S, Townsend P. D, Valbarg, L, “Low temperature radioluminecsence of Lif: Mg, Cu, P. Rad Prot Dos. 119, 134-8 (2006).

 

  1. Intenational Atomic Energy Agency. “Absorbed dose determination in external beam radiotherapy,” Vienna, IAEA, [Technical Reports Series No 398] (2000).

 

  1. A. Mesbahi, P. Mehnati, A. Keshtkar, “A comparative Monte Carlo study on 6MV photon beam characteristics of Varian 21EX and ElektaSL-25 linacs,” Iran. J. Radiat. Res. 5, 161-168 (2007).

 

  1. A. Mesbahi, “Development a simple point source model for Elekta SL-25 linear accelerator using MCNP4C Monte Carlo code,” Iran. J. Radiat. Res. 4, 7-14 (2006).

 

  1. A. Mesbahia, M. Fixb, M. Allahverdia, E. Greinc, H. Garaati, “Monte Carlo calculation of Varian 2300C/D Linac photon,” Beam Characteristics: a comparison between MCNP4C, GEANT3 and measurements. App. Rad. Iso. 62, 469-477(2005).

 

  1. A. Mesbahi, “Dosimetric characteristics of unflattened 6MV photon beams of a clinical linear accelerator: A Monte Carlo study,” App. Rad. Iso. 65, 1029-1036 (2007).

 

Keywords

Quality Audit
Radiotherapy
Phantom
Ionization Chamber
Thermoluminescent Dosimetry
Quality Control
Photon Beams
Monte Carlo Method

  1.  

     

    1. Martin CJ and Sutton DG, “Practical radiation protection in healthcare,” New York, Oxfor University Press Inc (2003).

       

    2. Intenational Atomic Energy Agency, “Quality assurance in radiotherapy,” Vienna, IAEA (1997).

     

    1. Intenational Atomic Energy Agency. “Comprehensive QA for radiation oncology,” American Association of Physicisits in Medicin. Vienna, IAEA (1994).

     

    1. Hoornaert MTh VDJ, Vynckier S, Bouiller A, “A dosimetric quality audit of photon beams by the Belgian Physicist Association,” Radiother Oncol, 28:37-43 (1993).

     

    1. Kalef-Ezra JA, Boziria A, Litsas J, Tsekeris P, Koligliatis T. “Thermoluminecense doimetry for quality assurance in radiation therapy,” Rad Prot Dos. 101:403-5 (2002).

     

    1. Podgorsak EB. “Radiation oncology physics: a handbook for teachers and student,” Vienna: IAEA (2005).

     

    1. MA EK, Harrison D, Cornes S J, Howlett DJ, Joseph T, Kron CS, Hamilton JW, Denham B. “Comprehensive Australasian multicentre dosimetric intercomparison,” Issues, logistics and recommendations. Med Imag & Rad Oncol, 53:119-131 (2009).

     

    1. Nisbet A TD, Sheridan ME, “A dosimetric intercomparison of kilovoltage X-rays, megavoltage photons and electrons in the Republic of Ireland,” Radiother Oncol, 48(1): 95-101 (1998).

     

    1. Nisbet A TD, “A dosimetric intercomparison of electron beams in UK radiotherapy centres,” Phys Med Biol, 42(12), 2393-409 (1997).

     

    1. Hansson U JK, “Quality audit of radiotherapy with EORTC mailed in water TL dosimetry,” Radiother Oncol. 20(3), 191-6 (1991).

     

    1. Davis B FP. “Quality audit of megavoltage radiotherapy units: intercomparison of dose at a reference point using mailed TL-dosimetry system,” Radiother Oncol, 28(1), 79-81 (1993).

     

    1. Dutreix A vdSE, Derreumaux S, Chavaudra J. “Preliminary results of a quality assurance network for radiotherapy centers in Euroupe,” Radiother Oncol, 29, 97-101 (1993).

     

    1. Huntley R IJ, “The 1998 Australian external beam radiotherapy survey and IAEA/WHO TLD postal quality audit,” Australas Phys Eng Sci Med. 23(1), 21-9 (2000).

     

    1. Aguirre JF TR, Ibbott G, Stovall M, Hanson, W, “Thermoluminescence dosimetry as a tool for the remot verification of output for radiotherapy beams: 25 years of experince,” In proceedings of the International Symposium on Standards and Codes of Practice in Medical Radiation Dosimetry IAEA, Vienna, IAEA (2002).

    2. J.H. Lee CYY, S.M. Hsu, M.Y. Shi, W.L. Chen, C.F. Wang, “Simple dose verification system for radiotherapy radiation,” Rad Meas. 43, 954-8 (2008).

     

    1. Arib M YA, Messadi A, Dari F. “Optimum parameters of TLD100 powder used for radiothrapy beams calibration check,” Med Dosim. 31, 4-9 (2006).

     

    1. Kroutilikova D NJ, Judas L. “Thermolumonescense dosimetrs(TLD) quality assurance network in the Czech Republic,” Radiother Oncol. 66, 35-44 (2003).

     

    1. Kron T HC, Roff M, Denham J, “Dosimetric intercomparison for two Australasian clinical trials using an anthropomorphic phantom,” IntRadiat Oncol Biol Phys. 52, 66-79 (2002).

     

    1. Kurt K MVK, McKeever S. W. S, Townsend P. D, Valbarg, L, “Low temperature radioluminecsence of Lif: Mg, Cu, P. Rad Prot Dos. 119, 134-8 (2006).

     

    1. Intenational Atomic Energy Agency. “Absorbed dose determination in external beam radiotherapy,” Vienna, IAEA, [Technical Reports Series No 398] (2000).

     

    1. A. Mesbahi, P. Mehnati, A. Keshtkar, “A comparative Monte Carlo study on 6MV photon beam characteristics of Varian 21EX and ElektaSL-25 linacs,” Iran. J. Radiat. Res. 5, 161-168 (2007).

     

    1. A. Mesbahi, “Development a simple point source model for Elekta SL-25 linear accelerator using MCNP4C Monte Carlo code,” Iran. J. Radiat. Res. 4, 7-14 (2006).

     

    1. A. Mesbahia, M. Fixb, M. Allahverdia, E. Greinc, H. Garaati, “Monte Carlo calculation of Varian 2300C/D Linac photon,” Beam Characteristics: a comparison between MCNP4C, GEANT3 and measurements. App. Rad. Iso. 62, 469-477(2005).

     

    1. A. Mesbahi, “Dosimetric characteristics of unflattened 6MV photon beams of a clinical linear accelerator: A Monte Carlo study,” App. Rad. Iso. 65, 1029-1036 (2007).

     

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