Sains Malaysiana 49(3)(2020): 693-701

http://dx.doi.org/10.17576/jsm-2020-4903-24

Monte Carlo Investigation on Neutron Dosimetry Parameters of ²⁵²Cf Isotron Brachytherapy Source

(Kajian Monte Carlo ke atas Parameter Dosimetri Neutron Sumber Brakiterapi ²⁵²Cf Isotron)

OME LEILA AHMADI & HOSSEIN TAVAKOLI-ANBARAN*

Faculty of Physics and Nuclear Engineering, Shahrood University of Technology, Shahrood, Iran

Received: 22 June 2019/Accepted: 11 November 2019

Abstract

In the present study, all dosimetry parameters around the ²⁵²Cf Isotron source for neutron brachytherapy were calculated. The ²⁵²Cf neutron energy spectrum was modeled using the Maxwellian spectrum. The calculations were performed using MCNPX.2.6.0 code based on the TG-43U1 protocol in the water medium. The neutron air kerma strength for the ²⁵²Cf Isotron source was computed as 0.3098 ± 0.0002 cGy cm²/µgh and the neutron dose rate constant was 6.559 ± 0.003 cGy/Uh. The anisotropy functions were calculated at intervals of 1, 2, 3, 4, and 5cm at different polar angles in the range of θ = 0̊ to 90º in respect to the source long axis in a water Phantom. The uncertainty of the calculated data at all distances is less than 1%. The radial dose function at different distances from the source for the Isotron model was compared with the theoretical HDR ²⁵²Cf source model. The discrepancies between the results were the highest at the distance of 0.5 cm, with relative differences of 5.64 %. For the ²⁵²Cf Isotron source, the data presented in this study provides better understanding on the dosimetric distribution of a theoretical neutron brachytherapy source, for potential clinical application.

Keywords: Brachytherapy; Isotron; neutron dosimetry; ²⁵²Cf

Abstrak

Dalam kajian ini, semua parameter dosimetri sekitar sumber Isotron ²⁵²Cf  untuk brakiterapi neutron dihitung. Spektrum tenaga neutron ²⁵²Cf dimodelkan menggunakan spektrum Maxwellian. Pengiraan dilakukan menggunakan kod MCNPX.2.6.0 berdasarkan protokol TG-43U1 dalam medium air. Kekuatan kerma udara neutron untuk sumber Isotron ²⁵²Cf dihitung sebagai 0.30986 ± 0.0002 cGy cm²/µgh dan kadar dos neutron tetap ialah 6.559 ± 0.003 cGy/Uh. Fungsi anisotropi dihitung pada selang 1, 2, 3, 4 dan 5 cm pada sudut polar yang berbeza dalam julat θ = 0º hingga 90º berkenaan dengan paksi panjang sumber dalam Phantom air. Ketidakpastian data yang dihitung pada semua jarak adalah kurang daripada 1%. Fungsi dos radial pada jarak yang berbeza daripada sumber untuk model Isotron dibandingkan dengan model sumber HDR ²⁵²Cf teoritis. Perbezaan antara keputusan adalah yang tertinggi pada jarak 0.5 cm, dengan perbezaan relatif 5.64%. Bagi sumber Isotron ²⁵²Cf, data yang dibentangkan dalam kajian ini memberikan pemahaman yang lebih baik mengenai pengagihan dosimetri sumber brakiterapi neutron teoritis, untuk aplikasi klinikal yang berpotensi.

Kata kunci: Brakiterapi; dosimetri neutron; Isotron; ²⁵²Cf

REFERENCES

Al-Saihati, I. & Naqvi, A.A. 2013. Neutron and gamma-ray doses from a ²⁵²Cf brachytherapy source in a water phantom. J. Radioanal. Nucl. Chem. 296: 963-966.

Fortune, E., Gauld, I. & Wang, C. 2011. Gamma dose near a new miniature Cf‐252 brachytherapy source. Med. Phys. 175: 73-76.

Ghassoun, J. 2013. Effect of tissue inhomogeneities on dose distributions from Cf-252 brachytherapy source. Appl. Radiat. Isot. 71(1): 1-6.

Ghassoun, J., Mostacci, D. & Molinari, V. 2010. Detailed dose distribution prediction of ²⁵²Cf brachytherapy source with boron loading dose enhancement. Applied Radiation and Isotopes 68: 265-270.

IAEA. 1987. Handbook on Nuclear Activation Data. VIENNA: IAEA International Atomic Energy Agency. p. 195.

Khosroabadi, M., Farhood, B., Rahmani, F., Ghorbani, M., Hamzian, M., Rezaei Moghaddama, H. & Davenport, D. 2016. Tissue composition effect on dose distribution in neutron brachytherapy/neutron capture therapy. Reports of Practical Oncology and Radiotherapy 21(1): 8-16.

Krishnaswamy, V. 1974. Calculated depth dose tables for californium-252 seed source in tissue. Phys. Med. Biol. 19: 886-888.

Melhus, C.S., Rivard, M.J., Kirk, B.L. & Leal, L.C. 2005. Clinical brachytherapy dosimetry parameters and mixed-field dosimetry for a high dose rate ²⁵²Cf brachytherapy source. In The Monte Carlo Method: Versatility Unbounded in a Dynamic Computing World. Amer. Nuc. Soc. p. 269.

Paredes, L., Azor´ınc, J., Balc´azara, M. & Francois, J.L. 2010. Neutron absorbed dose rate with ²⁵²Cf sources for medical applications. Revista mexicana de fisica S 56(1): 44-46.

Paredes, L., Azorin, J., Balcazar, M. & Francois, J.L. 2007. Neutrons absorbed dose rate calculations for interstitial brachytherapy with ²⁵²Cf sources. Nuclear Instruments and Methods in Physics Research A 580: 582-585.

Pelowitz, D. 2008. MCNPX User’s Manual. LA-CP-07-1473 Version 2.6.0. Los Alamos National Laboratory.

Radev, R. 2014. Neutron Sources for Standard-Based Testing. Lawrence Livermore National Laboratory.

Rivard, M.J. 2000. Neutron dosimetry for a general ²⁵²Cf brachytherapy source. Med. Phys. 27(12): 2803-2815.

Rivard, M.J., Coursey, B.M., DeWerd, L.A., Hanson, W.F., Saiful Huq, M., Ibbott, G.S., Mitch, M.G., Nath, R. & Williamson, J.F. 2004. Update of AAPM Task Group No. 43 Report: A revised AAPM protocol for brachytherapy dose calculations. Med. Phys. 31: 633-674.

Rivard, M.J., Wierzbicki, J.G., Van den Heuvel, F., Martin, R.C. & McMahon, R.R. 1999. Clinical brachytherapy with neutron emitting ²⁵²Cf sources and adherence to AAPM TG-43 dosimetry protocol. Med. Phys. 26(1): 87-96.

Venselaar, J.L.M., Baltas, D., Meigooni, A.S. & Hoskin, P.J. 2000. Comprehensive Brachytherapy Physical and Clinical Aspects. Boca Raton: Taylor & Francis Group.

Wang, C. & Kelm, R. 2009a. In-Water Neutron and Gamma Dose Determination for a New Cf-252 Brachytherapy Source. Georgia Institute of Technology.

Wang, C. & Kelm, R. 2009b. Determination of neutron and gamma dose rates in water surrounding a new interstitial ²⁵²Cf brachytherapy source. Med. Phys. 36: 2533-2533.

*Corresponding author; email: tavakoli-anbaran@shahroodut.ac.ir