Biological Tissue Modeling with Agar Gel Phantom for Radiation Dosimetry of 99mTc


The biological tissue has been mimicked and replaced by other materials, which have shown certain radiological similarity determined by attenuation coefficient (μ), density and atomic number. Specifically, in molecular imaging and radiation therapy have been developed multifunctional radiopharmaceuticals which contain beta/gamma and/or light emitters to chronic degenerative diseases treatment. Therefore, it is necessary to develop phantoms that allow optical and radiometric characterization. Since the agar gel has shown to be a medium which allows to model biological tissue in phototherapy studies, the aim of this study is to determine whether the agar gel may be used as biological tissue substitutes in 99mTc dosimetry. Agar gel was prepared to 1% and 2.3% (water:agar) and its radiologicalproperties as: linear attenuation coefficient obtained by narrow beam geometry and XCOM software, density and effective atomic number (Zeff) were determined. Using the determined μ, photontransmission was calculated by Monte Carlosimulation. The 99mTc source region was immersed in a water phantom, two source regions were used, one source region was filled with water and another with agar gel. For both cases; the cumulated activity () by conjugate view method, the absorbed doseper unitcumulated activity (S) and absorbed dose (D) were determined. The 2.3% concentration gel consistency facilitated its handling during a bigger irradiation time. A was obtained and also this value was corroborated with the XCOM software. The agar gel density was and . The calculated cumulated activity presented 1% difference in both phantoms. The absorbed doseper unitcumulated activity was the same in both media, therefore the D too. Agar gel showed to be equivalent to water in terms of radiological properties for 140 keV photons, thus it can substitute soft tissue in 99mTc dosimetry.

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Aranda-Lara, L. , Torres-García, E. and Oros-Pantoja, R. (2014) Biological Tissue Modeling with Agar Gel Phantom for Radiation Dosimetry of 99mTc. Open Journal of Radiology, 4, 44-52. doi: 10.4236/ojrad.2014.41006.

Conflicts of Interest

The authors declare no conflicts of interest.


[1] Khan, F.M. (2010) The Physics of Radiation Therapy. 4th Edition, Lippincott Williams & Wilkins, Philadelphia.
[2] White, D.R. (1978) Tissue Substitutes in Experimental Radiation Physics. Medical Physics, 5, 467-480.
[3] Keall, P., Kron, T. and Hoban, P. (1993) A Monte Carlo Technique to Establish the Water/Tissue Equivalence of Phantom Materials. Australasian Physical and Engineering Science in Medicine, 16, 125-128.
[4] Pantelis, E., Karlis, A.K., Kozicki, M., Papagiannis, P., Sakelliou, L. and Rosiak, J.M. (2004) Polymer Gel Water Equivalence and Relative Energy Response with Emphasis on Low Photon Energy Dosimetry in Brachytherapy. Physics in Medicine and Biology, 49, 3495-3514.
[5] Sellakumar, P., James, J.S. and Supe, S. (2007) Water Equivalence of Polymer Gel Dosimeters. Radiation Physics and Chemistry, 76, 1108-1115.
[6] Hill, R., Brown, S. and Baldock, C. (2008) Evaluation of the Water Equivalence of Solid Phantoms Using Gamma Ray Transmission Measurements. Radiation Measurements, 43, 1258-1264.
[7] Midgley, S.M. (2005) Measurements of the X-Ray Linear Attenuation Coefficient for Low Atomic Number Materials at Energies 32-66 and 140 keV. Radiation Physics and Chemistry, 72, 525-535.
[8] Gorjiara, T., Hill, R., Kuncic, Z., Bosi, S., Davies, J. and Baldock, C. (2011) Radiological Characterization and Water Equivalency of Genipin Gel for X-Ray and Electron Beam Dosimetry. Physics in Medicine and Biology, 56, 4685-4699.
[9] Traub, R.J., Olsen, P.C. and Mcdonald, J.C. (2006) The Radiological Properties of a Novel Lung Tissue Substitute. Radiation Protection Dosimetry, 121, 202-207.
[10] Venning, A.J., Nitschke, K.N., Keall, P.J. and Baldock, C. (2005) Radiological Properties of Normoxic Polymer Gel Dosimeters. Medical Physics, 32, 1047-1053.
[11] Taylor, M.L., Franich, R.D., Trapp, J.V. and Johnston, P.N. (2008) The Effective Atomic Number of Dosimetric Gels. Australasian Physical and Engineering Sciences in Medicine, 31, 131-138.
[12] Constantinou, C. (1982) Phantom Materials for Radiation Dosimetry. I. Liquids and Gels. British Journal of Radiology, 55, 217-224.
[13] Hartmann-Siantar, C.L., Walling, R.S., Daly, T.P., Faddegon, B., Albright, N., Bergstrom, P., Bielajew, A.F., Chuang, C., Garrett, D., House, R.K., Knapp, D., Wieczorek, D.J. and Verhey, L.J. (2001) Description and Dosimetric Verification of the PEREGRINE Monte Carlo Dose Calculation System for Photon Beams Incident on a Water Phantom. Medical Physics, 28, 1322-1337.
[14] Cubeddu, R., Pifferi, A., Taroni, P., Torricelli, A. and Valentini, G. (1997) A Solid Tissue Phantom for Photon Migration Studies. Physics in Medicine and Biology, 42, 1971-1979.
[15] Romo, G. and Camacho, S. (2007) Efectos de Calentamiento y Formación de Burbuja Inducidos con Láseres Pulsados en Modelos de Tejido-Biológico. Tesis de Maestría. Centro de Investigación Científica y de Educación Superior de Ensenada.
[16] Escobar, J.L., García, D.M., Zaldivar, D. and Katime, I. (2002) Hidrogeles: Principales Características en el Diseno de Sistemas de Liberación Controlada de Fármacos. Revista Iberoamericana Polímeros, 3, 1-25.
[17] Pal, K., Banthia, A.K. and Majumdar, D.K. (2009) Polymeric Hydrogels: Characterization and Biomedical Applications: A Mini Review. Designed Monomers and Polymers, 12, 197-220.
[18] Milanic, M., Majaron, B. and Stuart, J. (2007) Pulsed Photothermal Temperature Profiling of Agar Tissue Phantoms. Lasers in Medical Science, 22, 279-284.
[19] Melancon, M., Lu, W., Yang, Z., Zhang, Z., Cheng, Z., Stafford, J., Olson, T., Zhang, J. and Li, C. (2008) In Vitro and in Vivo Targeting of Hollow Gold Nanoshells Directed at Epidermal Growth Factor Receptor for Photothermal Ablation Therapy. Molecular Cancer Therapy, 7, 1730-1739.
[20] Jiménez, N., Ferro, G., Ocampo, B., Luna, M., Ramírez, F., Pedraza, M. and Torres, E. (2012) Multifunctional Targeted Radiotherapy System for Induced Tumours Expressing Gastrin-Releasing Peptide Receptors. Current Nanoscience, 8, 193-201.
[21] Ocampo, B., Ferro, G., Morales, E. and Ramírez, F. (2011) Kit for Preparation of Multimeric Receptor Specific 99mTc Radiopharmaceuticals Based on Gold Nanoparticles. Nuclear Medicine Communications, 32, 1095-1104.
[23] Attix, F.H. (1986) Introduction to Radiological Physics and Radiation Dosimetry. J. Wiley and Son, New York.
[25] Snyder, W., Ford, M. and Warner, G. (1978) MIRD Pamphlet No. 5. Revised: Estimated of Specific Absorbed Fractions for Photon Sources Uniformly Distributed in Various Organs of a Heterogeneous phantom.
[26] Buijs, W., Siegel, J.A., Boerman, O. and Corstens, F. (1998) Absolute Organ Activity Estimated by Different Methods of Background Correction. Journal of Nuclear Medicine, 39, 2167-2172.
[27] Siegel, J.A., Thomas, S.R., Stubbs, J.B. and Stabin, M.G. (1999) MIRD Pamphlet No. 16: Techniques for Quantitative Radiopharmaceutical Biodistribution Data Acquisition and Analysis for Use in Human Radiation Dose Estimates. Journal of Nuclear Medicine, 40, 31-68.
[28] Hill, L., Holloway, L. and Baldock, C. (2005) A Dosimetric Evaluation of Water Equivalent Phantoms for Kilovoltage X-Ray Beams. Physics in Medicine and Biology, 50, 331-344.
[29] Brown, S., Venning, S., De Deene, Y., Vial, P., Oliver, L., Adamovics, J. and Baldock, C. (2008) Radiological Properties of the PRESAGE and PAGAT Polymer dosimeters. Applied Radiation and Isotopes, 66, 1970-1974.
[30] ICRU (1989) Tissue Substitutes in Radiation Dosimetry and Measurement (Report 44).

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