Gold nanoparticles-based brachytherapy enhancement in choroidal melanoma   using a full Monte Carlo modelling of human eye
  The effects of gold nanoparticles in 125I brachytherapy dose enhancement on choroidal Melanoma are examined using the Monte Carlo simulation technique. Usually, Monte Carlo ophthalmic brachytherapy dosimetry is performed in a water phantom. However, here, the compositions of human eye have been considered instead of water. Both human eye and water phantoms have been simulated with MCNP5 code. These simulations were performed for a fully-loaded 16 mm COMS eye plaque containing 13 125I seeds. The dose delivered to the tumor and healthy tissues have been calculated in both phantoms, with and without GNPs. The results indicates that the dose to the tumor in an eye-ball implanted with COMS plaque increases with increasing GNPs concentration inside the target. Therefore, the required irradiation time for the tumors in the eye is decreased by adding the GNPs prior to treatment. As a result, the dose to healthy tissues decreases when the irradiation time is reduced. Furthermore, a comparison between the simulated data in an eye phantom made of water and eye phantom made of human-eye composition, in the presence of GNPs shows the significance of utilizing the composition of eye in ophthalmic brachytherapy dosimetry. Normally, the radiation therapy of cancer patients is designed to deliver a required dose to the tumor while sparing the surrounding healthy tissues. The results demonstrated that the use of GNPs enable us to overcome this challenge. Also, defining the eye composition instead of water will leads to more accurate calculations of GNPs radiation effects in ophthalmic brachytherapy dosimetry. 
Somayeh Asadi, Mehdi Vaez-zade, S. Farhad Masoudi, Faezeh Rahmani,   Courtney Knaup, Ali S. Meigooni
physics.med-ph