In-beam PET monitoring of mono-energetic¹⁶O and¹²C beams: experiments and FLUKA simulations for homogeneous targets

Abstract

(16)O and (12)C ion beams will be used-besides lighter ions-for cancer treatment at the Heidelberg Ion Therapy Center (HIT), Germany. It is planned to monitor the treatment by means of in-beam positron emission tomography (PET) as it is done for therapy with (12)C beams at the experimental facility at the Gesellschaft für Schwerionenforschung (GSI), Darmstadt, Germany. To enable PET also for (16)O beams, experimental data of the beta(+)-activity created by these beams are needed. Therefore, in-beam PET measurements of the activity created by (16)O beams of various energies on targets of PMMA, water and graphite were performed at GSI for the first time. Additionally reference measurements of (12)C beams on the same target materials were done. The results of the measurements are presented. The deduction of clinically relevant results from in-beam PET data requires reliable simulations of the beta(+)-activity production, which is done presently by a dedicated code limited to (12)C beams. Because this code is not extendable to other ions in an easy way, a new code, capable of simulating the production of the beta(+)-activity by all ions of interest, is needed. Our choice is the general purpose Monte Carlo code FLUKA which was used to simulate the ion transport, the beta(+)-active isotope production, the decay, the positron annihilation and the transport of the annihilation photons. The detector response was simulated with an established software that gives the output in the same list-mode data format as in the experiment. This allows us to use the same software to reconstruct measured and simulated data, which makes comparisons easier and more reliable. The calculated activity distribution shows general good agreement with the measurements.

Validation of recent Geant4 physics models for application in carbon ion therapy

“…A review of the pertinent literature demonstrates the increased attraction Monte Carlo codes have gained in the field of ion therapy in recent years: examples are the simulation of b þ -activity distributions in tissue-like materials for positron emission tomography (PET) as a means of dose monitoring [4][5][6][7], the Monte Carlo-based evaluation of water-to-air stopping power ratios for ionisation chamber dosimetry [8][9][10][11], the examination of the dependency of dose and radiation quality on the field size [12], the investigation of biological dose distributions [13], or the Monte Carlo-based prediction of radiochromatic film response [14]. The most common Monte Carlo packages used for such applications are FLUKA [15,16], Geant4 [17,18], SHIELD-HIT [19] and PHITS [20], where the first two packages are general-purpose Monte Carlo codes, emerging from the high-energy physics community.…”

A simulation study of a C-shaped in-beam PET system for dose verification in carbon ion therapy

“…The dose distribution is formed by a Coulomb interaction between the carbon ions and the target ions, while the activity distribution is created by a nuclear reaction between the projectiles and the target nuclei [13,17]. However, the two curves have similar peak positions.…”

Towards Offline PET Monitoring at a Cyclotron-Based Proton Therapy Facility

“…Introducing this agaragar powder into the water opens the additional isotope production channel 12 C(p,pn) 11 C. Sommerer et al [2009] judged the impact to be negligible for in-beam PET measurements. Instead of water, gelatine was used for the analysis of the three proton induced reaction channels with 16 O as mother isotope.…”