Measurement of PET isotope production cross sections for protons and carbon ions on carbon and oxygen targets for applications in particle therapy range verification

Felix Horst,Claire-Anne Reidel,Hans-Georg Zaunick,Christoph Schuy,Klemens Zink,Marta Rovituso,Marco Durante,Giulia Aricò,Wihan Adi,Kai-Thomas Brinkmann,Uli Weber

doi:10.1088/1361-6560/ab4511

Abstract

Measured cross sections for the production of the PET isotopes , and from carbon and oxygen targets induced by protons (40–220 ) and carbon ions (65–430 ) are presented. These data were obtained via activation measurements of irradiated graphite and beryllium oxide targets using a set of three scintillators coupled by a coincidence logic. The measured cross sections are relevant for the PET particle range verification method where accurate predictions of the emitter distribution produced by therapeutic beams in the patient tissue are required. The presented dataset is useful for validation and optimization of the nuclear reaction models within Monte Carlo transport codes. For protons the agreement of a radiation transport calculation using the measured cross sections with a thick target PET measurement is demonstrated.

Highlights

Radiotherapy with protons and heavy ions has many potential advantages over conventional techniques using high energy photons or electrons
It can be observed that for the graphite targets the activity decreases fast in the first two minutes after irradiation because the short-lived 10C dominates the activity while later only the produced 11C remains. In contrast to these distinct two decay components, the decay curves of the activated beryllium oxide are dominated by the produced 15O and the other produced isotopes (10C, 11C, 14O, 13N) only contribute a few percent to the total activity. It can be seen, that the produced activity per irradiation pulse was considerably lower for carbon ions than for protons which results in a lower signal to noise ratio
The PET counting statistics that can be collected for range verification during patient treatments with carbon ions suffers from this relation compared to proton therapy (Parodi et al 2002)

Summary

Introduction

Radiotherapy with protons and heavy ions (particle therapy) has many potential advantages over conventional techniques using high energy photons or electrons. Most of these advantages arise from the highly localized energy deposition pattern of heavy charged particles due to their electromagnetic interaction properties. These lead to the Bragg peak at the end of the particle range and in the case of heavy ions to a sharp lateral dose fall-off even at large depths. This allows for a better tumor conformity together with good sparing of healthy tissues (Schardt et al 2010, Newhauser and Zhang 2015). A fully developed range verification method could lead to reduced safety margins around the treatment volume and improve particle therapy in general

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Conclusion