Magic Polymer Gel Dosimetry Using X-Ray Computed Tomography: A Feasibility Study
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Date
2008-06
Authors
MOHAMMAD ALJAMAL, MOHAMMAD ABDALLA
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Abstract
The aim of this project is to carry out the feasibility study of developing MAGIC
(Methacrylic and Ascorbic acid in Gelatin Initiated by Copper) polymer gel dosimetry
system by utilising helical multislice X-ray computed tomography (CT) available in HUSM
to determine dose. The MAGIC gel was prepared based on the formulation proposed in the
literature by Fong et al. (2001) with some modifications. The characteristics of the gel were
studied for its water-equivalent properties. The mass density (P) was determined based on
Archimedes' principle. The weight fraction of elemental composition and the effective
atomic number (Zeff) were calculated. The electron density was also measured with 90 degree
scattering angle at room temperature. The linear attenuation coefficient (j1) of unirradiated
gel, irradiated gel, and water were determined using Am-241 based on narrow beam
geometry. The measured linear attenuation coefficient of unirradiated MAGIC gel and water
was found to be 0.84 ± 0.04 cm-I and 0.85 ± 0.02 cm-I respectively. The results showed that
the MAGIC gel is water-equivalent. The data obtained using irradiated gel showed a linear
relationship between linear attenuation coefficient and absorbed dose in the range 2 to 40 Gy.
The protocol for CT imaging to obtain the best quality image of irradiated MAGIC gel was
determined for evaluating dose information. The irradiated gel placed inside the cylindrical
water phantom was scanned using various available scan parameters (kV, rnA and
reconstruction algorithm) with the field of view 25 x 25 cm2 and 5 mm slice thickness.
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Keywords
Magic Polymer Gel Dosimetry Using X-Ray Computed Tomography , A Feasibility Study