Comparative Study of Experimental Enhancement in Free Radical Generation against Monte Carlo Modeled Enhancement in Radiation Dose Deposition Due to the Presence of High Z Materials during Irradiation of Aqueous Media


Purpose: To investigate conflicting results demonstrating higher cell-kill by irradiated high atomic number (Z) material, gold (Au) in tumor compared to Monte Carlo (MC) modeled enhancement in radiation dose deposition, and to compare the difference between radiosensitizing effects of gold and platinum. Methods and Materials: Since a majority of cell kill due to radiation is mediated by free radicals, evaluation of radicals generated from radiolysis of an aqueous medium can provide some insight into cell-kill. Here, free radicals generated due to the radiolysis of water by a clinical Iridium-192 (Ir-192) brachytherapy source in the presence and absence of thin and pure gold or platinum wires were quantified with electron paramagnetic/spin resonance (EPR/ESR) spectrometry and enhancements in free radical generation due to the presence of the wires during radiolysis were calculated. Those enhancements were compared against MC modeled enhancement in radiation dose deposition obtained from the geometry replicating the experimental setup. Results: Enhancements in free radical generation due to 100 and 127 μm diameter gold wires, and 127 μm diameter platinum wire were more than two times higher than the corresponding MC modeled enhancements in radiation dose deposition. Enhancement in hydroxyl free radical (OH?) generation due to thicker wires of gold and platinum were close to the enhancements in radiation dose deposition. The effects were similar for gold and platinum wires of equal diameter. Conclusions: Higher enhancement in radical generation compared to MC modeled enhancement in radiation dose deposition due to micron-size pure gold and platinum wires demonstrates that the surfaces of high Z materials in aqueous media become a secondary source of radicals under radiation field. High surface-to-volume ratio of nanoparticles can make this effect more pronounced, leading to higher cell kill than the predictions based on pure dose enhancement.

Share and Cite:

Paudel, N. , Shvydka, D. and Parsai, E. (2015) Comparative Study of Experimental Enhancement in Free Radical Generation against Monte Carlo Modeled Enhancement in Radiation Dose Deposition Due to the Presence of High Z Materials during Irradiation of Aqueous Media. International Journal of Medical Physics, Clinical Engineering and Radiation Oncology, 4, 300-307. doi: 10.4236/ijmpcero.2015.44036.

Conflicts of Interest

The authors declare no conflicts of interest.


[1] Hall, E.J. and Giaccia, A.J. (2006) Radiobiology for the Radiologist. 6th Edition, Lippincott Williams and Wilkins, Philadelphia.
[2] Hainfeld, J.F., Slatkin, D.N. and Smilowitz, H.M. (2004) The Use of Gold Nanoparticles to Enhance Radiotherapy in Mice. Physics in Medicine and Biology, 49, N309-N315.
[3] Herold, D.M., Das, I.J., Stobbe, C.C., et al. (2000) Gold Microspheres: A Selective Technique for Producing Biologically Effective Dose Enhancement. International Journal of Radiation Biology, 76, 1357-1364.
[4] Detappe, A., Tsiamas, P., Ngwa, W., et al. (2013) The Effect of Flattening Filter Delivery on Endothelial Dose Enhancement with Gold Nanoparticles. Medical Physics, 40, (031706-1)-(031706-4).
[5] Sech, C.L., Kobayashi, K., Ushami, N., et al. (2012) Comment on Therapeutic Application of Metallic Nanoparticles Combined with Particle Induced X-Ray Induced X-Ray Emission Effect. Nanotechnology, 23, 78001.
[6] Carter, J.D., Cheng, N.N., Qu, Y., et al. (2007) Nanoscale Energy Deposition by X-Ray Absorbing Nanostructures. Journal of Physical Chemistry B, 111, 11622-11625.
[7] Regulla, D.F., Hieber, L.B. and Seidenbusch, M. (1998) Physical and Biological Interface Dose Effects in Tissue Due to X-Ray-Induced Release of Secondary Radiation from Metallic Gold Interfaces. Radiation Research, 150, 92-100.
[8] Das, I.J., Moskvin, V.P., Kassaee, A., et al. (2002) Dose Perturbations at High-Z Interfaces in Kilovoltage Photon Beams: Comparison with Monte Carlo Simulations and Measurements. Radiation Physics and Chemistry, 64, Article ID: 1730179.
[9] Regulla, D., Schmid, E., Friedland, W., et al. (2002) Enhanced Values of the RBE and H Ratio for Cytogenetic Effects Induced by Secondary Electrons from an X-Irradiated Gold Surface. Radiation Research, 158, 505-515.[0505:EVOTRA]2.0.CO;2
[10] Walzlein, C., Scifoni, E., Kramer, M., et al. (2014) Simulations of Dose Enhancement by Heavy Atom Nanoparticles Irradiated by Protons. Physics in Medicine and Biology, 59, 1441-1458.
[11] Mishawa, M. and Takahashi, J. (2011) Generation of Reactive Oxygen Species Induced by Gold Nanoparticles under X-Ray and UV Irradiations. Nanomedicine: Nanotechnology, Biology and Medicine, 7, 604-614.
[12] Cheng, N.N., Starkewolf, Z., Davidson, R.A., Sharmah, A., Lee, C., Lien, J. and Guo, T. (2012) Chemical Enhancement by Nanomaterials under Irradiation. Journal of the American Chemical Society, 134, 1950-1953.
[13] Sicard-Roselli, C., Brun, E., Gilles, M., Baldacchino, G., Kelsey, C., McQuaid, H., et al. (2014) A New Mechanism for Hydroxyl Radical Production in Irradiated Nanoparticle Solutions. Small, 10, 3338-3346.
[14] Lechtman, E., Chattopadhyay, N., Cai, Z., Mashouf, S., Reilly, R. and Pignol, J.P. (2011) Implications on Clinical Scenario of Gold Nanoparticle Radiosensitization in Regards to Photon Energy, Nanoparticle Size, Concentration and Location. Physics in Medicine and Biology, 56, 4631-4647.
[15] McMahon, S.J., Hyland, E.B., Muir, M.F., Coulter, J.A., Jain, S., Butterworth, K.T., et al. (2011) Nanodosimetric Effects of Gold Nanoparticles in Megavoltage Adiation Therapy. Radiotherapy and Oncology, 100, 412-416.
[16] Jain, S., Coulter, J.A., Hounsell, A.R., Butterworth, K.T., McMahon, S.J., Hyland, W.B., et al. (2011) Cell Specific Radiosensitization by Gold Nanoparticles at Megavoltage Radiation Energies. International Journal of Radiation Oncology, Biology, Physics, 79, 531-539.
[17] Liu, C.J., Wang, C.H., Chen, S.T., Chen, H.H., Leng, W.H., Chien, C.C., et al. (2010) Enhancement of Cell Radiation Sensitivity by Pegylated Gold Nanoparticles. Physics in Medicine and Biology, 55, 931-945.
[18] Chithranii, D.B., Jelveh, S., Jalai, F., van Prooijen, M., Allen, C., Bristow, R.G., et al. (2010) Gold Nanoparticles as Radiation Sensitizers in Cancer Therapy. Radiation Research, 173, 719-728.
[19] Marcu, L., Doorn, T.V. and Olver, I. (2003) Cisplatin and Radiotherapy in the Treatment of Locally Advanced Head and Neck Cancer. Acta Oncologica, 42, 315-325.
[20] Perez, E.A. (2004) Carboplatin in Combination Therapy for Metastatic Breast Cancer. Oncologist, 9, 518-527.
[21] Usami, N., Kobayashi, K., Furusawa, Y., Frohlich, H., Lacombe, S. and Le Sech, C. (2007) Irradiation of DNA Loaded with Platinum Containing Molecules by Fast Atomic Ions C6+ and Fe26+. International Journal of Radiation Biology, 83, 569-576.
[22] Saifutdinov, R.G., Larina, L.I., Vakul’skyaya, T.I. and Voronkov, M.G. (2002) Electron Paramagnetic Resonance in Biochemistry and Medicine. Kluwer Academic Publishers, New York.
[23] Buettner, G.R. and Oberley, L.W. (1978) Considerations in the Spin Trapping of Superoxide and Hydroxyl Radical in Aqueous Systems Using 5,5-Dimethyl-1-Pyrroline-Oxide. Biochemical and Biophysical Research Communications, 83, 69-74.
[24] X-5 Monte Carlo Team (2004) MCNP—A General Monte Carlo N-Particle Transport Code. Version 5, Vol. 1, Los Alamos National Laboratory, Los Alamos.
[25] Carmichael, A.J., Makino, K. and Riesz, P. (1984) Quantitative Aspects of ESR and Spin Trapping of Hydroxyl Radicals and Hydrogen Atoms in Gamma-Irradiated Aqueous Solutions. Radiation Research, 100, 222-234.
[26] Nishikawa, H. (2003) Radical Generation on Hydroxyapatite by UV Radiation. Material Letters, 58, 14-16.
[27] Jackson, S.D. and Hargreaves, J.S.J. (2009) Metal Oxide Catalysis. Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim.
[28] Paudel, N., Shvydka, D., Findsen, E. and Parsai, E. (2014) Experimental Evaluation of Free Radical Generation in Nanoparticle-Aided HDR Brachytherapy. International Journal of Radiation Oncology, Biology, Physics, 90, S198-S199.
[29] Paudel, N., Shvydka, D. and Parsai, E. (2012) Micro-Dosimetry Study of the Radiation Dose Enhancement at the Gold-Tissue Interface for Nanoparticle-Aided Radiation Therapy. Medical Physics, 39, 3775.
[30] Paudel, N.R. (2014) Nanoparticle-Aided Radiation Therapy: Microdosimetry and Evaluation of Mediators Producing Biological Damage. Ph.D. Dissertation, The University of Toledo, Toledo.
[31] Henglein, A. (1989) Small-Particle Research: Physiochemical Properties of Extremely Small Colloidal Metal and Semiconductor Particles. Chemical Reviews, 89, 1861-1873.
[32] Zhang, X.D., Guo, M.L., Wu, H.Y., Sun, Y.M., Ding, Y.Q., Feng, X. and Zhang, L.A. (2009) Irradiation Stability and Cytotoxicity of Gold Nanoparticles for Radiotherapy. International Journal of Nanomedicine, 4, 165-173.

Copyright © 2021 by authors and Scientific Research Publishing Inc.

Creative Commons License

This work and the related PDF file are licensed under a Creative Commons Attribution 4.0 International License.