Short-lived radioactive 8 Li and 8 He ions for hadrontherapy: a simulation study.

Although charged particle therapy (CPT) for cancer treatment has grown these past years, the use of protons and carbon ions for therapy remains debated compared to x-ray therapy. While a biological advantage of protons is not clearly demonstrated, therapy using carbon ions is often pointed out for its high cost. Furthermore, the nuclear interactions undergone by carbons inside the patient are responsible for an additional dose delivered after the Bragg peak, which deteriorates the ballistic advantage of CPT. Therefore, a renewed interest for lighter ions with higher biological efficiency than protons was recently observed. In this context, helium and lithium ions represent a good compromise between protons and carbons, as they exhibit a higher linear energy transfer (LET) than protons in the Bragg peak and can be accelerated by cyclotrons. The possibility of accelerating radioactiveLi, decaying in 2-particles, andHe, decaying inLi bydecay, is particularly interesting.. This work aims to assess the interest of the use ofLi andHe ions for therapy by Monte Carlo simulations carried out withGeant4.. It was calculated that theLi andHe decay results in an increase of the LET of almost a factor 2 in the Bragg peak compared to stableLi andHe. This results also in a higher dose deposited in the Bragg peak without an increase of the dose in the plateau region. It was also shown that bothHe andLi can have a potential interest for prompt-gamma monitoring techniques. Finally, the feasibility of accelerating facilities deliveringLi andHe was also discussed.. In this study, we demonstrate that bothLi andHe have interesting properties for therapy. Indeed, simulations predict thatLi andHe are a good compromise between proton andC, both in terms of LET and dose.