Monte Carlo study on the gold and gadolinium nanoparticles radio-sensitizer effect in the prostate ¹²⁵I seeds radiotherapy

Abstract

Monte Carlo and TL dosimetry applied to the characterization of 125I brachytherapy with a different design with other 125I seeds. In a water phantom, lattice configuration simulated with 125I seed in the center and 10 nm gold and gadolinium nan-particle filed voxels. This simulation conducted to the characterization of the nano-particles DEF in low energy and prostate tissue. To study of the prostate brachytherapy, a humanoid computational phantom developed by CT slices applied. KTMAN-2 computational phantom contains 29 organs and 19 skeletal regions and was produced from cross-sectional x-ray computed tomography (CT slices) images. The simulated seed was 125I seed having an average energy of 28.4 keV for photons, a half-life of 59.4 days. DEF factor in the seed radiation energy (28.4 keV) DEF factor was found to be two times higher for the gold nano-particles. It was revealed than gold-nano-particles posing Z about 1.24 times higher than gadolinium led to around 200% DEF increasing in the same conditions and the nano-particles size. It was concluded that in low energy sources brachytherapy, photoelectric is dominant in the presence of relative high element nanoparticles. This leads to a high dose increasing in some micro-meters and causes a dramatic dose gradient in the vicinity of a nano-particle. This dose gradient effectively kills the tumor cells in continuous low energy irradiation in the presence of a high Z material nano-scaled particle. Application of gold nano-particles in low energy brachytherapy is recommended.

Nanoscale dosimetric consequences around bismuth, gold, gadolinium, hafnium, and iridium nanoparticles irradiated by low energy photons

“…Application of nanoparticles in medical radiation physics, medical imaging, and radiation therapy of cancer has been reported by enormous studies. [1][2][3][4][5][6][7][8][9][10] Several nanoparticles have been used and studied for application in nanoparticle-aided radiation therapy (NART) with the photons in the energy range of tens to hundreds of keV. 2,5,[11][12][13][14][15][16][17] The studies showed that photoelectrons produced through photoelectric interaction of photons with high Z atoms of nanoparticles are the major players in the extra dose delivered around the nanoparticles.…”

“…[1][2][3][4][5][6][7][8][9][10] Several nanoparticles have been used and studied for application in nanoparticle-aided radiation therapy (NART) with the photons in the energy range of tens to hundreds of keV. 2,5,[11][12][13][14][15][16][17] The studies showed that photoelectrons produced through photoelectric interaction of photons with high Z atoms of nanoparticles are the major players in the extra dose delivered around the nanoparticles. 15,18 However, after the photoelectric phenomenon, in addition to photoelectrons, the auger electrons, characteristics x-rays, other secondary electrons are released from nanoparticles and deliver a high dose near the surface of nanoparticles.…”