E Jimenez-ortega¹, D Gonzalez-castano², J Lopez-valverde³*, F Gomez⁴, A Leal Plaza⁵, (1) University Of Seville, ,,(2) University Of Santiago De Compostela, ,,(3) University Of Seville, ,,(4) University of Santiago, Santiago Compo, ,ES, (5) University of Seville, Seville, Seville, ES

MO-H345-IePD-F3-2 (Monday, 7/11/2022) 3:45 PM - 4:15 PM [Eastern Time (GMT-4)]

Exhibit Hall | Forum 3

Purpose: In radiotherapy (RT), gold nanoparticles (GNPs) arouse especial interest due to the possibility of enhancing the imaging contrast for diagnosis and increasing the dose efficacy for therapy. Many studies have shown theoretical calculations about the ability of GNPs to achieve an increase in the dose deposited in the tumour. However, as far as we know, it has not been possible to carry out an experimental verification with the traditional systems of the increase in the dose, because of the short range of the particles that cause it (mainly Auger electrons). Our proposal is to use of a liquid-filled ionisation chamber with GNPs, to measure the increase in the dose.

Methods: A liquid-filled ionisation chamber (NanoLIC) and a simple phantom of solid water to host the chamber have been designed. The active medium was liquid isooctane. Also, we used a special preparation of 5nm GNPs functionalized with isooctane and dodecanethiol, which are both non-polar and hydrophobic mediums, to measure the possible dose enhancement due to the presence of the GNPs. The camera was irradiated with different field sizes and at different depths with the Megavoltage Cone Beam Imaging system of a Siemens Oncor linac. This beam has a nominal energy close to 4MV, but lower (around 1MV) under the multileaf collimator. This allowed the development of a proof-of-concept with energy low enough to have the dose enhancement due to GNPs and high enough to be used in clinical treatment. On the other hand, Monte Carlo simulation of the experimental measurements was carried out through the codes EGSnrc, BEAMnrc, and DOSXYZnrc.

Results: The preliminary results showed a good camera response, which is in agreement with the results obtained with MC.

Conclusion: The nanoLIC camera can be an innovative system for experimental verification of dose enhancement due to the presence of GNPs.

Funding Support, Disclosures, and Conflict of Interest: Funding Support: Ministerio de Ciencia e Innovacion and Agencia Estatal de Investigacion of Spain: RTI2018-098656-B-I00; European Regional Development Fund (FEDER): RTI2018-098656-B-I00

Keywords

Liquid Ionization Chamber

Taxonomy

TH- Radiation Dose Measurement Devices: ion chamber: liquid

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