TITLE:
Biological Tissue Modeling with Agar Gel Phantom for Radiation Dosimetry of 99mTc
AUTHORS:
Liliana Aranda-Lara, Eugenio Torres-García, Rigoberto Oros-Pantoja
KEYWORDS:
Agar Gel; 99mTc; Radiation Dosimetry; Tissue Substitute
JOURNAL NAME:
Open Journal of Radiology,
Vol.4 No.1,
February
20,
2014
ABSTRACT: 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.