Malaysian Journal of Analytical Sciences Vol 18 No 2 (2014): 423 – 433

 

 

 

role of anti-oxidants on normoxic METHACRYLIC ACID GELATIN (MAG) polymer gel dosimeter at 6-MV photon beam using single spin echo MRI

 

(Peranan Anti-Oksida Dalam Normosik Asid Methakrilik Gelatin (MAG) Dosmeter Gel Polimer Pada 6-MV Sinaran Photon  Menggunakan  Aturan Nada Denyut Tunggal MRI)

 

Nik Noor Ashikin Nik Ab Razak¹*, Azhar Abd Rahman¹, Sivamany Kandaiya¹,  Iskandar Shahrim¹, Nor Zakiah Yahaya¹, Noor Faizura Zainal², Eng Kae Yann³

 

¹School of Physics,

Universiti Sains Malaysia, 11800 Minden,  Penang, Malaysia

²Imaging Department, Institut Perubatan dan Pergigian Termaju (Advanced Medical & Dental Institute),

Universiti Sains Malaysia, 13200 Kepala Batas, Penang, Malaysia

³Radiotherapy and Oncology Department,

Pantai Mutiara Hospital, 11900 Penang, Malaysia

 

*Corresponding author: ohm_poisse@yahoo.com

 

 

Abstract

The primary goal of radiation therapy is to deliver a sufficient radiation dose to a target volume while minimizing the dose to surrounding healthy tissue. In this study the dose response of methacrylic acid-gelatin (MAG) polymer gel dosimeter using different type of anti-oxidants; ascorbic acid (AscA) and tetrakis-hydroxy-methyl-phosphonium chloride (THPC) is determined by using single spin echo sequence magnetic resonance imaging (MRI). The concentrations of methacrylic acid (MAA) were varied and using MRI, the optimal formulation that gives the maximum R2-dose response of the polymer gel upon irradiation was determined. The polymer gel was irradiated using a 6 MV photon from a linear accelerator (LINAC) for a dose range varying from 0 to 20 Gy. The transverse relaxation rates (R2) of the irradiated gels from MRI were read. A linear relationship between dose and R2 was obtained for a dose range of 0 to 20 Gy for MAG gel composed of ascorbic acid (MAGAS) and linear response from 0 to 10 Gy for MAG gel composed of THPC (MAGAT). The sensitivity of MAGAS showed lower sensitivity compared to MAGAT. The optimum concentrations for the MAGAS and MAGAT polymer gel were 6% MAA and 5% gelatin as it gave the highest sensitivity of 0.0989 s^-1Gy^-1 and 1.1180 s^-1Gy^-1 respectively.  The results are compared to Multiple Spin Echo Sequence MRI.

 

Keywords: MAGAS polymer gel, MAGAT polymer gel, dose sensitivity, ascorbic acid, THPC, single spin echo sequence

 

Abstrak

Tujuan utama radioterapi adalah untuk memberi dos sinaran yang mencukupi kepada isipadu sasaran sementara meminimumkan jumlah dos di sekitar tisu yang sihat. Dalam kajian ini tindak balas dos oleh asid metakrilik-gelatin (MAG) dosmeter gel polimer menggunakan anti-oksida yang berlainan iaitu asid askorbik (AscA) dan tetrakis-hydroxy-methyl-phosphonium chloride (THPC) telah di kaji menggunakan aturan nada denyut tunggal MRI. Kepekatan methacrylic acid (MAA) di ubah dan dengan menggunakan MRI, komposisi yang optimum di perolehi daripada tindak balas dos yang maksimum pada gel selepas di iridiasi. Gel polimer diiridiasi oleh 6-MV sinaran photon dari pemecut linear (LINAC) untuk linkungan dos dari 0 sehingga 20 Gy. Kadar relaksasi melintang (R2) bagi gel yang telah di iridiasi di ukur oleh MRI. Satu hubungan berkadar lurus di antara dos dengan R2 di perolehi pada julat dos 0 sehingga 20 Gy bagi gel MAG yang mengandungi asid askorbik (MAGAS) dan hubungan berkadar lurus dari 0 sehingga 10 Gy untuk gel MAG yang mengandungi THPC (MAGAT). Kepekatan optimum bagi MAGAS dan MAGAT gel polimer diperolehi daripada 6% MAA dan 5% gelatin yang menghasilkan nilai sensitif yang paling tinggi iaitu masing-masing 0.0989 s^-1Gy^-1 dan 1.1180 s^-1Gy^-1. Hasil kajian akan di bandingkan dengan urutan nada denyut berganda.

 

Kata kunci: Polimer gel MAGAS, polimer gel MAGAT, sensitiviti dos, asid askorbik, tetrakis-hydroxy-methyl-phosphonium chloride (THPC)

 

References

1.      Maryanski, M.J., Gore, J.C., Kennan, R.P. & Schulz, R.J. (1993 ). NMR relaxation enhancement in gels polymerized and cross-linked by ionizing radiation: a new approach to 3D dosimetry. MRI Magn. Reson. Imaging, 11:  253–258.

2.      Day, M.J., Andrews, H.L., Murphy, R.E. & Lebrun, E.J. (1957). Gel dosimeter for depth dose measurements. Review of Scientific Instruments, 28: 329–332.

3.      Day, M.J. and G. Stein. (1950). Chemical effects of ionising radiation in some gels. Nature, 166: 146–147.

4.      Doran, S.J., K.K. Koerkamp, M.A. Bero, P. Jenneson, E.J. Morton, and W.B. Gilboy. (2001). A CCD-based optical CT scanner for high-resolution 3D imaging of radiation dose distributions: equipment specifications, optical simulations and preliminary results. Phys. Med. Biol., 46:  3191–3213.

5.      Doran, S.J. (2013). How to perform an optical CT scan: an illustrated guide. Journal of Physics: Conference Series, 444 (1):  012004.

6.      Jirasek, A. (2010).  Alternative imaging modalities for polymer gel dosimetry. Journal of Physics: Conference Series, 250:  012070.

7.      Baldock, C., Y. De Deene, S. Doran, G. Ibbott, A. Jirasek, M. Lepage, K.B. McAuley, M. Oldham, and L.J. Schreiner. (2010). Polymer gel dosimetry. Phys. Med. Biol., 55 p. R1–R63

8.      Doran, S.J. (2010). Imaging and 3-D dosimetry: top tips for MRI and optical CT. Journal of Physics: Conference Series,  250(1):  012086.

9.      Low, D.A., J. Markman, J.F Dempsey, S. Mutic, M. Oldham, R. Venkatesan, E.M. Haacke, and J.A. Purdy. (2000.).   Noise in polymer gel measurements using MRI. Med. Phys., 27:  1814-1817.

10.  De Deene, Y., R. Van de Walle, E. Achten, and C. De Wagter. (1998). Mathematical analysis and experimental investigation of noise in quantitative magnetic resonace imaging applied in polymer gel dosimetry. Sig Proc., 70:. 85-101.

11.  De Deene, Y. and C. Baldock. (2002).Optimization of multiple spin-echo sequences for 3D polymer gel dosimetry. Phys. Med.Biol.,  47:  3117-3141.

12.  Baldock, C., M. Lepage, S. Back, P. Murry, P. Jayasekera, D. porter, and T. Kron. (2001). Dose resolution in radiotherapy polymer gel dosimetry: effect of echo spacing in MRI pulse sequence. Phys. Med. Biol., 46:  449-460.

13.  Maryanski, M.J., R.J. Schulz, G.S. Ibbotq, J.C. Gatenby, J. Xiell, D. Hortonq, and J.C. Gore. (1994).  Magnetic resonance imaging of radiation dose distributions using a polymer-gel dosimeter. Phys. Med. Biol., 39: 1437-1455.

14.  Hepworth, S.J., M.O. Leach, and S. Dorran. (1999).  Dynamics of polymerisation in polyacrylamide gel (PAG) dosimeters: (II) modelling oxygen diffusion. Phys. Med. Biol., 440:  3105 -3113.

15.  Maryanski, M.J., G.S. Ibbott, P. Eastman, R.J. Schulz, and J.C. Gore. (1996). Radiation therapy dosimetry using resonance imaging of polymer gels. Med. Phys., 23:  699–705.

16.  Baldock, C., R.P. Burford, N. Billingham, G.S. Wagner, S. Patval, R.D. Badawi, and S.F. Keevil. (1998). Experimental procedure for the manufacture and calibration of polyacrylamide gel (PAG) for magnetic resonance imaging (MRI) radiation dosimetry. Phys. Med.Biol., 43:  695-702.

17.  Fong, P.M., D.C. Keil, M.D. Does, and J.C. Gore. (2001). Polymer gels for magnetic resonance imaging of radiation dose distributions at normal room atmosphere. Phys. Med. Biol., 46:  3105–3113.

18.  De Deene, Y., C. Hurley, A. Venning, K. Vergote, M. Mather, B..J Healy, and C. Baldock.  (2002).  A basic study of some normoxic polymer gel dosimeters. Phys. Med. Biol., 47 p. 3441–3463.

19.  Ibbott, G.S., M.J. Maryanski, P. Eastman, S.D. Holcomb, Y.S. Zhang, R.G. Avison, M. Sanders, and J.C. Gore. (1997). 3D visualization and measurement of conformal dose-distributions using MRI of BANG-gel dosimeters. Int.J. Radiat. Oncol. Biol. Phys.,  38:  1097–1103.

20.  Oldham, M., I.B. Baustert, C. Lord, T.A.R. Smith, M. McJury, M. Leach, A.P. Warrington, and S. Webb. (1998).  An investigation into the dosimetry of a 9 field tomotherapy irradiation using BANG-gel dosimetry. Phys. Med. Biol., 43:  1113–1132.

21.  Jason J.S. Lee, Chia-Jung Tsai, Man-Kuok Lo, Yung-Hui Huang , Chien-Chuan Chen, Jay Wu, Yeu-Sheng Tyan, and Tung-Hsin Wud. (2008). Investigation of dose characteristics in three-dimensional MAGAT-type polymer gel dosimetry with MSE MR imaging. Nuclear Instruments and Methods in Physics Research B, 266:  2199–2202.

22.  Jirasek, A. (2006).  Experimental investigations of polymer gel dosimeters. J.Physics: Conference Series,  56: 23–34.

23.  Venning, A., B. Healy, K. Nitschk, and C Baldock. (2005). Investigation of the MAGAS normoxic polymer gel dosimeter with Pyrex glass walls for clinical radiotherapy dosimetry. Nuclear Instruments and Methods in Physics Research A, 555:  396–402.

24.  Shin-ichiro, H., Y. Munenori, U. Shuji, H. Kiyofumi, K. Takahiro, k.B. McAuley, and T. Takahiro. (2010).  A study on the role of gelatin in methacrylic-acid-based gel dosimeters. Radiation Physics ans Chemistry, 79:  803–808

25.  Yoshioka, M., S. Hayashi, S. Usui, K. Haneda, H.  Numasaki, T.  Teshima, and T.  Tominaga. (2009).   A new polymer gel dosimeter composed of methacrylic acid,agarose gel and THPC with gelatin. J.Physics: Conference Series, 164:  012013.