Medical Physics Seminar – Monday, December 12, 2022

Monte Carlo modeling and dosimetry of a dynamic collimation system for pencil beam scanning proton therapy


Nicholas Nelson
Research Assistant, UW-Madison

The Dynamic Collimation System (DCS) is an energy layer-specific external collimation device designed to improve the lateral conformity in low-energy pencil beam scanning proton therapy (PBS-PT)treatments. The DCS consists of two pairs of nickel trimmers that rapidly and independently move and rotate to intercept scanning proton beams as they approach the target edge, that significantly reduces the adjacent normal tissue dose. The aim of this work is to integrate and validate previously theorized dosimetric benefits of the DCS equipped to a clinical proton beamline through Monte Carlo simulations and experimental dosimetry methods.

Development of a primary standard for absorbed dose to water from alpha-emitting radionuclides


Ahtesham Ullah Khan
Research Assistant, UW-Madison

Targeted radionuclide therapy(TRT)with alpha particles has recently gained significant clinical relevance. A typical workflow for patient-specific TRT dosimetry involves calculation of absorbed dose in a patient-specific voxelized geometry using computational methods such as dose point kernels or Monte Carlo simulations. Thus, experimental validation of Monte Carlo codes is needed. While traceability based on radioactivity is currently established, there is a lack of direct traceability and measurement of absorbed dose in the dosimetry chain. Therefore, the aim of this work was to develop and evaluate two windowless parallel-plate ionization chambers as primary standards for absorbed dose to water from alpha-emitting radionuclides.

Location: HSLC 1325


Time: 4:00-5:00