SU‐E‐T‐384: Dosimetry Studies for Radioactive Gold Nanoparticles

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Purpose: This investigation was initiated to determine the absorbed dose and radioactivity distribution of radioactive gold nanoparticles.Methods: Polymer gel dosimeter was prepared using about 12% gelatin (Sigma Aldrich, 300 bloom type A), 9% methacrylic acid(Sigma Aldrich), 10mM THPC (Sigma Aldrich), 18mM hydroquinone (Sigma Aldrich) in deionized water. These dosimeters are used for calibration purpose and meant to estimate the absorbed dose in the medium from the radiation emitted by the radioactive gold nanoparticles. The high energy gamma dose, activity distribution were measured using SPECT imaging and the phantom used was the ball of play‐doh made by Hasbro Toys. A previously constructed acrylic cast of beagle dogˈs head was used in this study to place the phantom. The radioactive gold nanoparticles were synthesized at the University owned nuclear reactor with the high neutron flux of ∼10e14 neutrons/cm2/sec.Results: Carbohydrate suspended radioactive nanoparticles with approximately 200 microCuries were injected in a play doh ball, depicting the prostate gland of beagle dog, approximately 1 inch diameter (8–10ml) in size. The phantom was placed on the SPECT imaging table near the isocenter of the imaging plane. The Gamma camera was peaked for the 411keV photon and equipped with a high energy (Iodine collimator). The phantom was then imaged using SPECT imaging protocol. The activity imaged at various planes and count rates was evenly distributed as predicted Conclusions: The activity distribution as seen in the SPECT imaging indicated active hot and cold spots of radioactive gold nanoparticles. The use of play‐doh determines the activity distribution but uneven diffusion. To compensate for that polymer gel dosimeters, equivalent to the tissue densities may be considered, besides there is also an advantage of estimating the absorbed doses.