Sains Malaysiana 46(2)(2017): 303–308

http://dx.doi.org/10.17576/jsm-2017-4602-15

6 MV Photon Beam Induced UV/VIS Absorption of Hema Polymer Gel

(Alur Foton 6 MV Teraruh Penyerapan UV/VIS Gel Polimer HEMA)

SITI ATIQAH ISHAK*, ISKANDAR SHAHRIM , SITI, K.A.R.

& AZHAR A. ALRAHMAN

School of Physics, Universiti Sains Malaysia, 11800 Pulau Pinang, Malaysia

Received: 22 August 2014/Accepted: 24 May 2016

ABSTRACT

The aim of this study was to evaluate properties of normoxic polymer gel 2-Hydroxyethyl methacrylate monomer (HEMAG) as a point dosimeter by using optical properties evaluation techniques. HEMAG were prepared from seven different radiation dose within five different depths of HEMAG dosimeters. These HEMAG dosimeters were irradiated by linear accelerator with 6 MV photon beams. The absorption spectra were measured by using a UV-visible spectrophotometer in the wavelength range from 300 to 800 nm. Then, the data was analysed to determine the optical energy band gap (Eg) and Urbach’s energy (ΔE). The result showed that Eg and ΔE were dependent on radiation dose and percentage of depth dose (PDD). In additional, Eg with indirect transition of HEMAG decreased as radiation dose increased and increased with traversing of depth. ΔE of HEMAG increased as the dose increased and decreased with traversing depth of monomer. There was a shift in the Eg values towards lower energy as the dose increased and led to a shift of the ΔE value towards the higher energy with increasing dose. This observation supported the increase of structured disorder of the polymer with increasing radiation dose, which resulted in the lower energy transitions that was feasible and reduced the values of Eg. In conclusion, HEMAG has a potential to be used as a dosimeter at low radiation dose in the clinical radiotherapy.

Keywords: HEMAG; optical properties; optical band gap; polymer gel; Urbach energy; UV-vis spectrophotometer

ABSTRAK

Tujuan kajian ini ialah untuk menilai sifat poli-hidroksimetilakrilit gel (HEMAG) sebagai dosimeter titik dengan menggunakan teknik penilaian sifat optik. HEMAG disediakan daripada tujuh dos sinaran berbeza dilingkungi lima kedalaman dosimeter HEMAG yang berbeza. Dosimeter HEMAG dipersinarkan menggunakan pemecut linear dengan alur foton 6 MV. Spektra serapan diukur dengan menggunakan spektrofotometer UV-nampak pada julat panjang gelombang dari 300 hingga 800 nm. Kemudian, data dianalisis untuk menentukan jurang jalur tenaga optik (Eg) dan tenaga Urbach (ΔE). Keputusan menunjukkan Eg dan ΔE bergantung kepada dos sinaran dan peratus kedalaman dos (PDD). Sebagai tambahan, Eg dengan transisi tak langsung HEMAG berkurang apabila dos sinaran meningkat dan meningkat dengan penyusuran kedalaman. ΔE HEMAG meningkat apabila dos meingkat dan menurun dengan penyusuran kedalaman monomer. Terdapat anjakan di dalam nilai Eg terhadap tenaga rendah apabila dos meningkat dan menjurus ke anjakan nilai ΔE terhadap tenaga tinggi dengan penigkatan dos. Pemerhatian ini menyokong peningkatan ketaktertiban berstruktur polimer dengan peningkatan dos, yang dihasilkan di dalam tenaga transisi rendah yang tersaur dan mengurangkan nilai-nilai Eg. Secara kesimpulan, HEMAG mempunyai potensi untuk digunakan sebagai dosimeter pada dos sinaran rendah di dalam radioterapi klinikal.

Kata kunci: Gel polimer; HEMAG; jalur tenaga optik; sifat optik; spektrofotometer UV-vis; tenaga Urbach

REFERENCES

Chahal, R.P. 2011. Effect of ultraviolet irradiation on the optical and structural characteristics of in-situ prepared PVP-Ag nanocomposites. Digest Journal of Nanomaterials and Biostructures 6(1): 299-306.

Cho, S.J., Shin, D., Huh, H.D., Lee, S.H., Lim, S.W., Yun, H.G., Yun, S.M., Shin, D.O., Yang, D.S., Park, Y.J., Kim, C.Y. & Lee, S. 2007. Development of a novel normoxic polymer gel dosimeter (TENOMAG). Journal of the Korean Physical Society 51(5): 1798-1804.

Elias Saion, Susilawati, Doyan, A., Zainal Abidin, S., Azmi, Z., Zulkfli, A., Mohd Zaki, A.R., Dahlan, K.Z.H. & Karni, T. 2005. Changes in the optical band gap and absorption edge of gamma-irradiated polymer blends. Journal of Applied Sciences 5(10): 1825-1829.

Hawkins, A.R. & Holger, S. 2010. Handbook of Optofluidics. New York: Taylor & Francis Group. doi:10.1038/ncomms1662.

Maryanski, M.J., Zastavker, Y.Z. & Gore, J.C. 1996. Radiation dose distributions in three dimensions from tomographic optical density scanning of polymer gels: II. Optical properties of the BANG polymer gel radiation dose distributions in three dimensions from tomographic optical density scanning of poly. Physic in Medicine and Biology 41: 2705-2717.

Podgorsak, E. 2005. Radiation Oncology Physics: A Handbook for Teachers and Students. International Atomic Energy Agency. doi:10.1038/sj.bjc.6604224.

Susilawati & Doyan, A. 2009. Dose response and optical properties of dyed poly vinyl alcohol-trichloroacetic acid polymeric blends irradiated with gamma-rays. American Journal of Applied Sciences 6(12): 2071-2077.

*Corresponding author; email: sitiatiqah.ishak@gmail.com