title: Dose enhancement in gold nanoparticle-aided radiotherapy for the therapeutic photon beams using Monte Carlo technique.
abstract: BACKGROUND
  Gold nanoparticle (GNP)-aided radiation therapy (RT) is useful to make the tumor more sensitive to radiation damage because of the enhancement in the dose inside the tumor region. Polymer gel dosimeter (PGD) can be a good choice for the physical measurement of dose enhancement produced by GNP inside the gel.
  
  
  METHODS
  The present study uses EGSnrc Monte Carlo code to estimate dose enhancement factor (DEF) due to the introduction of GNPs inside the PGD at different concentrations (7 and 18 mg Au/g of gel) when irradiated by therapeutic X-rays of energy 100 kVp, 150 kVp, 6 MV, and 15 MV. The simulation was also carried out to quantify the dose enhancement in PAGAT gel and tumor for 100 kVp X-rays.
  
  
  RESULTS
  For 100 kVp X-rays, average DEF of 1.86 and 2.91 is observed in the PAGAT gel dosimeter with 7 and 18 mg Au/g of gel, respectively. Average DEF of 1.69 and 2.61 is recorded for 150 kVp X-rays with 7 and 18 mg Au/g of gel, respectively. No clinically meaningful DEF was observed for 6 and 15 MV photon beams. Furthermore, the dose enhancement within the PAGAT gel dosimeter and tumor closely matches with each other.
  
  
  CONCLUSIONS
  The polymer gel dosimetry can be a suitable method of dose estimation and verification for clinical implementation of GNP-aided RT. GNP-aided RT has the potential of delivering high localized tumoricidal dose with significant sparing of normal structures when the treatment is delivered with low energy X-rays.
authors: Nitin Ramesh
authors: NR
authors: Kakade
authors: Radiological Physics and Advisory Division, Bhabha Atomic Research Centre, Anushakti Nagar, Mumbai, Maharashtra, India.
authors: Sunil Dutt
authors: SD
authors: Sharma
mesh_terms: D006046:Gold; D006801:Humans; D053768:Metal Nanoparticles; D009010:Monte Carlo Method; D009369:Neoplasms / Q000532:radiotherapy; D017785:Photons; D011874:Radiometry / Q000379:methods*; D011878:Radiotherapy / Q000379:methods*; D011879:Radiotherapy Dosage; D014965:X-Rays
chemical_list: D006046:Gold