Comparative treatment planning in radiotherapy and clinical impact of proton relative biological effectiveness.

摘要: Currently, most clinical range-modulated proton beams are assumed to have a fixed overall relative biological effectiveness (RBE) of 1.1. However, it is well known that the RBE increases with depth in spread-out Bragg peak (SOBP) and becomes about 10% higher than mid-SOBP at 2 mm from distal edge (Paganetti 2003 Technol. Cancer Res. Treat. 413-26) can reach values 1.3-1.4 vitro (Robertson et al 1975 35 1664-77, Courdi 1994 Br. J. Radiol. 67 800-4). We present fast method for applying variable correction linear energy transfer (LET) dependent tissue-specific parameters based on alpharef/betaref ratios suitable implementation treatment planning system. The influence this multiple beam dose plan presented here. evaluated by weighted volume histograms (DVHs) calculation tumour control probability (TCP) normal tissue complication (NTCP) values. yields DVHs target volumes (CTVs), primary advanced hypopharynx cancer subclinical disease lymph nodes, slightly those achieved multiplying absorbed RBE=1.1. Although, more importantly, DVH an organ risk, spinal cord considerably increased RBE. As particular case located 8 behind (PTV) hence receives only low total doses, NTCP zero spite significant increase high non-target were obtained when correction. variations tend be smaller vivo systems, study-based data since human scarce large uncertainties-can interpreted as showing upper limits possible effects utilizing In conclusion, results here still indicate difference introducing compared generic 1.1, suggesting worth considering such therapy planning, especially risk organs immediately volume.