03/24/2026
By Aaron Fishbein

The Kennedy College of Science, Department of Physics and Applied Physics, invites you to attend a Master’s Thesis defense by Aaron Fishbein on “A Monte-Carlo Evaluation of Gadolinium as a Neutron Capture Agent in Nanoparticle-Aided Radiotherapy.”

Candidate Name: Aaron Fishbein
Degree: Master’s
Date: Monday, April 6, 2026
Time: 11 a.m.
Location: Olney Hall, Room 136D (Department Conference Room), North Campus
Thesis/Dissertation Title: A Monte-Carlo Evaluation of Gadolinium as a Neutron Capture Agent in Nanoparticle-Aided Radiotherapy

Committee:

  • Advisor Marian Jandel, Ph.D., Department of Physics and Applied Physics, UMass Lowell
  • Romy Guthier, Ph.D., Department of Physics and Applied Physics, UMass Lowell
  • Erno Sajo, Ph.D., Department of Physics and Applied Physics, UMass Lowell

Brief Abstract:
Neutron capture therapy (NCT), first proposed in 1936, has seen a renewal of interest in recent decades due to advances in neutron production, as well as nanoparticle delivery methods. NCT involves using a highly collimated beam of neutrons to irradiate a lesion loaded with a neutron capturing agent to increase interaction frequency in the cancerous cells. Gadolinium is one of the leading proposed captured agents for NCT due to two of its naturally occurring isotopes having large neutron capture cross sections and the capture reaction producing highly damaging internal conversion electrons and a subsequent Auger cascade. Gadolinium is also FDA-approved for use in several MRI contrast agents, opening the door for hybrid theranostic treatments. This work seeks to compare dosimetrically important characteristics of thermal neutron irradiation of a gadolinium nanoparticle to thermal neutron irradiation of boron-10 and photon irradiation of gold and gadolinium by using Geant4, a general-purpose Monte Carlo toolkit. DICEBOX – a Monte-Carlo-based gamma cascade simulation software – is used to simulate the de-excitation of Gadolinium nuclei through the dense, quasi-continuum of nuclear energy states after a capture event. Quantities such as local dose deposition characteristics, secondary particle generation, ionization density, and the dose increase relative to other nanoparticle modalities are evaluated. Results demonstrate a large dose enhancement for thermal neutron irradiation of gadolinium nanoparticles when compared to both photon simulations. While boron outperforms gadolinium in respect to dose deposition and ionization frequency within the first 100nm of the nanoparticle, gadolinium secondaries are farther ranged and create a much shallower dose and ionization gradient which can contribute to more uniform cell mortality.