Room: AAPM ePoster Library
Heavy-ion therapy (HT) is gaining popularity with more facilities coming online in the near future. The high linear energy transfer of ions, and the Bragg peak featured in the dose profile are considerable advantages to HT. However, the lack of an exit dose makes it very challenging to monitor and verify the correct treatment delivery in-vivo and in real time. While some methods allow for indirect measurement of the ion range (e.g. PET, prompt ? emission), they are often time consuming and rely on comparison to a Monte Carlo simulation or calibration. We have established a novel technique that measures the range of the heavy ion beam directly.
During HT, secondary particles, including ? rays, are naturally produced through nuclear interactions with tissue. If a carefully chosen metal Hadron Tumour Marker (HTM) is administered close to the tumor, some ions will undergo nuclear reactions with the marker to produce characteristic ? rays via different reaction channels. As the different channels are strongly energy dependent, the ratio of the measured characteristic ?-ray lines is a measure of the beam energy at the position of the HTM. As the HTM is very close to the tumour, the conversion of this measurement to range is very precise.
Monte Carlo simulations indicate that our method allows sub-millimetre measurements of the ion beam range. We will present the results of a first proof-of-principle experiment conducted at the National Superconducting Cyclotron Laboratory, Michigan State University with a 150 MeV/u ¹6O beam of clinical intensity.
Our novel range-verification technique is a promising method to significantly reduce uncertainties in HT and to further increase the therapeutic index.
Funding Support, Disclosures, and Conflict of Interest: We acknowledge the support of the CIHR, NSERC and SSHRC (under Award No. NFRFE-2018-00691)