Treatment Planning: comparing techniques and standards

To highlight merits and pitfalls of treatment plan comparison between photon-based conventional radiation therapy (XRT) and particle-based (proton and carbon ions) therapy (PT).

The physical and dosimetric rationales for the use of PT will be explored looking at their advantages and disadvantages with a specific focus on sensitivity to range and biological uncertainties. Next, the analysis will focus on linear energy transfer (LET) and its correlation with relative biological effectiveness (RBE), particularly within the context of plan optimization and evaluation phases in proton therapy. This examination aims to address the impact of the LET/RBE interplay on radiobiological uncertainties.

There is a wide literature of planning studies comparing PT and the most advanced XRT techniques. Purely dosimetric advantages are translated into normal tissue complication probability (NTCP) variation to drive patient optimal allocation, but the impact of range uncertainty needs to be accounted for, together with the consequent need for plan adaptation and organ motion management. RBE modelling and entailed clinical effects are currently central in PT research, while new degrees of freedom are being introduced with LET-based plan optimization and evaluation.

PT shows many dosimetric advantages but emphasizes challenges like range uncertainty. RBE modelling plays a crucial role, and LET-based optimization introduces new possibilities. Addressing uncertainties and embracing innovation are vital for enhancing PT’s efficacy.