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Dose Rate Determination of Gamma Rays Emitted by Thallium-201 and Technetium-99m Using a Modified Horseradish Peroxidase Based Biosensing System

M. Shourian^a, H. Ghourchian^a,*, H.-A. Rafiee-Pour^a and H. Tavakoli^b  

^aLaboratory of Microanalysis, Institute of Biochemistry and Biophysics, University of Tehran, P.O. Box 13145-1384, Tehran, Iran

^bFaculty of Medicine, Department of Physiology and Biophysics, Baghiyatollah University of Medical Sciences, Tehran, Iran

In the presence of low energy gamma emitter radioisotopes of thallium-201 (²⁰¹Tl) or technetium-99m (^99mTc), H₂O₂ was generated via radiolysis of water. The produced H₂O₂ was amperometrically determined using an anthraquinone 2-carboxylic acid modified horseradish peroxidase on glassy carbon electrode. In the presence of each radioisotope, the cathodic current produced due to the amperometric detection of H₂O₂, was designated as biosensor response. At the applied potential of -550 mV (vs. Ag/AgCl), the biosensor showed the sensitivities of 1.937 and 2.278 nA h �µGy^-1 towards H₂O₂ produced by ²⁰¹Tl and ^99mTc respectively. Finally, the calibration curves for dose rate determination of ²⁰¹Tl and ^99mTc have been presented and the correlations between biosensor response to H₂O₂ and the gamma emitter dose rates for ²⁰¹Tl and ^99mTc are established.

Keywords: Thallium-201, Technetium-99m, Gamma ray, Hydrogen peroxide, Horseradish peroxidase, Anthraquinone 2-carboxylic acid