Electron emission spectra from gold-nanoparticles for dose estimation in radiation therapy
Nuclear Medicine, Radiotherapy, Radiobiology
Final Report Abstract
Electron emission spectra have been measured for the first time on gold nanoparticles with photons and protons at energies relevant for therapeutic applications. By carefully characterizing the experimental apparatus with auxiliary measurements, it was possible to obtain these data on an absolute scale. A first proof-of-principle comparison between the measurement results of additional measurements on gold foils and Monte Carlo simulations of these effects has been conducted. The outcome was that, on the one hand, evidence was produced that the information from auxiliary measurements on the experimental apparatus, which was used in the data analysis of the experiments, was correctly determined. On the other hand, is turned out that simplifications made in the simulation codes complicate the comparison with experiments. For instance, photon polarization is not taken into account in the simulations, while it was a key feature of the experimental facility used for the photon experiments. Another interesting finding was that the energy positions of the LMM Auger electrons differed between experiments, on the one hand, and simulations and the internationally recognized evaluated atomic data library (EADL), on the other. Theoretical calculations have been performed that suggest that the calculations used to produce the information in the EADL may have incorrectly assumed that Auger transitions energies and probabilities can be simply calculated from the properties of the neutral atom. Our results show that the observed Auger electron energies are compatible with full relaxation of the ions involved in the process, which requires a more sophisticated approach for calculating the transition probabilities. Another interesting, even though not so scientific, finding was made during this project in a reevaluation of the reported results an international code comparison exercise, where large discrepancies had been reported previously (that motivated conducting the measurements in this project). The reevaluation revealed that the discrepancies were in part due to mistakes in the data analysis of the exercise and, in a major part, to the fact that only two out of eleven participants performed the exercise according to what was requested, while all others deviated from the exercise definition and thus produced variant result. In the course of identifying these issues, a set of consistency checks were developed that can be used in future similar activities to faster identify mistakes. A by-product of these activities was the development of a procedure that allows estimating the correct results from simulations that were biased in their setup.
Publications
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Correcting the lack of secondary particle equilibrium in simulations of nanoparticle-induced dose enhancement. in: Christian Streffer, Christoph Reiners, Franz Fehringer, Martina Froning (Eds.), Strahlenschutz und Medizin, Patienten – Beschäftigte – Gesellschaft, Proc. 51. Jahrestagung Fachverband für Strahlenschutz e. V. (Würzburg, Germany, 09-12.09.2019), TÜV Media GmbH, Köln 2019, ISBN: 978-3-7406- 0446-2, FS-2019-179-T 191-196
Rabus H, Gargioni E, Nettelbeck H, Villagrasa
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Corrigendum to "Intercomparison of dose enhancement ratio and secondary electron spectra for gold nanoparticles irradiated by X-rays calculated using multiple Monte Carlo simulation codes” [Phys. Med. 69 (2020) 147–163]. Physica Medica, 80 (2020, 12), 383-388.
Li, W.B.; Beuve, M.; Di Maria, S.; Friedland, W.; Heide, B.; Klapproth, A.P.; Li, C.Y.; Poignant, F.; Rabus, H.; Rudek, B.; Schuemann, J. & Villagrasa, C.
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Intercomparison of dose enhancement ratio and secondary electron spectra for gold nanoparticles irradiated by X-rays calculated using multiple Monte Carlo simulation codes. Physica Medica, 69, 147-163.
Li, W.B.; Belchior, A.; Beuve, M.; Chen, Y.Z.; Di Maria, S.; Friedland, W.; Gervais, B.; Heide, B.; Hocine, N.; Ipatov, A.; Klapproth, A.P.; Li, C.Y.; Li, J.L.; Multhoff, G.; Poignant, F.; Qiu, R.; Rabus, H.; Rudek, B.; Schuemann, J.; ... & Zhang, Y.B.
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Consistency checks of results from a Monte Carlo code intercomparison for emitted electron spectra and energy deposition around a single gold nanoparticle irradiated by X-rays. Radiation Measurements, 147, 106637.
Rabus, H.; Li, W.B.; Nettelbeck, H.; Schuemann, J.; Villagrasa, C.; Beuve, M.; Di Maria, S.; Heide, B.; Klapproth, A.P.; Poignant, F.; Qiu, R. & Rudek, B.
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Intercomparison of Monte Carlo calculated dose enhancement ratios for gold nanoparticles irradiated by X-rays: Assessing the uncertainty and correct methodology for extended beams. Physica Medica, 84, 241-253.
Rabus, H.; Li, W.B.; Villagrasa, C.; Schuemann, J.; Hepperle, P.A.; de la Fuente Rosales, L.; Beuve, M.; Di Maria, S.; Klapproth, A.P.; Li, C.Y.; Poignant, F.; Rudek, B. & Nettelbeck, H.
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Deposition of Gold Nanoparticles on a Self‐Supporting Carbon Foil. Particle & Particle Systems Characterization, 39(11).
Hepperle, Philine; Baek, Woon Yong; Nettelbeck, Heidi & Rabus, Hans
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XPS Examination of the Chemical Composition of PEGMUA‐Coated Gold Nanoparticles. Particle & Particle Systems Characterization, 39(9).
Hepperle, Philine; Herman, Alexander; Khanbabaee, Behnam; Baek, Woon Yong; Nettelbeck, Heidi & Rabus, Hans
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Experimental benchmark data for Monte Carlo simulated radiation effects of gold nanoparticles. Part I: Experiment and raw data analysis. Physica Scripta, 98(5), 055015.
Rabus, Hans; Hepperle, Philine; Schlueter, Christoph; Hloskovsky, Andrei & Baek, Woon Yong
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Experimental benchmark data for Monte Carlo simulated radiation effects of gold nanoparticles. Part II: comparison of measured and simulated electron spectra from gold nanofoils. Physica Scripta, 98(5), 055016.
Borbinha, Jorge; de la Fuente Rosales, Liset; Hepperle, Philine; Nettelbeck, Heidi; Baek, Woon Yong; Di, Maria Salvatore & Rabus, Hans
