Towards a Three Dimensional Dosimetry Based On Diffusion Imaging Tools
J Davila1*, R Martin2, (1) Centro Medico Docente La Trinidad, Municipio Baruta, ,(2) Universidad Central de Venezuela, Pearland, TXSU-E-T-98 Sunday 3:00PM - 6:00PM Room: Exhibit Hall
Purpose: To explore the possibilities of easy to handle and low cost alternatives for the required dosimetry in many applications of radiation oncology based on diffusion imaging tools.
Methods:Spherical phantoms of 15 cm in diameter were filled with a gel made as a mixture of a polysaccharide (fructose, 80% w/w) and gelatin (20% w/w). The phantoms were irradiated using two perpendicular photon beams with a 6 MV LINAC at a rate of 600 MU/min and doses of 30 Gy (25 mm cones), 100 Gy (20 mm cones) and 300 Gy (25 mm cones). In order to obtain the effective diffusion coefficient profiles the phantom irradiated at 30 Gy was scanned in a 1.5 Tesla MRI equipment 2 hours after irradiation while for the others the waiting time was 24 hours. Finally they were compared with the TPS absorbed dose profiles.
Results:A remarkable correlation between the effective diffusion coefficient and TPS absorbed dose is observed in all cases. The system has a memory, i. e., the produced alteration or damage can last long enough to be observed and its mean life increases with the absorbed dose.
Conclusion:The effective diffusion coefficient can be correlated with the absorbed dose in gels made out of polysaccharides and gelatin. This material has a long enough memory to be useful in several applications related to radiation dosimetry.
Funding Support, Disclosures, and Conflict of Interest: Founding was provided by Fisica Medica C. A. (a company of the GURVE Radiation Oncology Group) and the School of Physics, Faculty of Science, Universidad Central de Venezuela
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