Investigation the effect of a magnetic field on the dose distribution of I-125, Ir-192, Yb-169, and Co-60 brachytherapy sources by Monte Carlo simulation

Appl Radiat Isot. 2022 Sep:187:110332. doi: 10.1016/j.apradiso.2022.110332. Epub 2022 Jun 12.

Abstract

Magnetic resonance imaging (MRI) during brachytherapy may alter the dose distribution of radioactive sources implanted in the tumor. This study investigates the impact of a magnetic field of 1.5 T, 3 T, and 7 T strengths on the dose distribution of high dose rate Co-60, Ir-192, and Yb-169, and low dose rate I-125 sources, using Geant4 Monte Carlo toolkit. After validating the simulation results by calculating the AAPM-TG43 dosimetric parameters, seven sources of each radioisotope were simulated in a water phantom, and their dose distributions were compared under the influence of a magnetic field. The simulation results indicate that using Co-60 brachytherapy under the MRI guidance is not recommended. Furthermore, the impact of a magnetic field of up to 7 T strength on the dose distribution of Ir-192, Yb-169, and I-125 sources is negligible, provided that there is no air pocket near brachytherapy sources.

Keywords: Brachytherapy; Geant4; Magnetic field; Monte Carlo simulation; Prostate cancer.

MeSH terms

  • Brachytherapy* / methods
  • Cobalt Radioisotopes / therapeutic use
  • Iodine Radioisotopes
  • Iridium Radioisotopes* / therapeutic use
  • Magnetic Fields
  • Monte Carlo Method
  • Radiometry / methods
  • Radiotherapy Dosage

Substances

  • Cobalt Radioisotopes
  • Iodine Radioisotopes
  • Iridium Radioisotopes
  • Iridium-192
  • Cobalt-60
  • Iodine-125