MSc Thesis Presentation: Experimental Validation of Filtered Interaction Vertex Imaging for Intra-Fraction Relative Range Verification in Heavy-Ion Therapy

MSc Candidate

Devin Hymers

Abstract

The growing societal burden of cancer necessitates improvements in the safety and efficacy of  treatment.  Scanned  heavy-ion  therapy  provides  precise  and  highly  conformal  radiation  treatment  of  tumours,  but  it  is  difficult  to  ensure  accurate  dose  delivery  due  to  uncertainty  surrounding  ion  beam  range  in  tissue.  Relative  range  verification  via  filtered  interaction  vertex  imaging could monitor the spacing of each treatment beam endpoint, ensuring full and consistent tumour  coverage.  To  validate  this  method,  twelve 16O  beams  of  differing  energy  irradiated  a  40 mm poly-(methyl methacrylate) phantom. Secondary particles were monitored using position-sensitive silicon detectors, and used to reconstruct the depth distribution of beam-phantom nuclear reactions. Comparison of logistic fits to the distal edges of these distributions computed the range shift between two energies to sub-millimeter precision with a standard deviation of the mean of 220(10)μm,  validating  filtered  interaction  vertex  imaging  as  a  candidate  for  clinical  high-performance range verification.

Examination Committee

• Dr. Robert Wickham, Chair
• Dr: Carl Svensson, Advisor
• Dr. Ralf Gellert
• Dr. Michael Massa