Relative biological effectiveness (RBE)
How many grays of ordinary X-rays you would need to match the damage from one gray of this radiation. Protons are treated as 1.1 times as damaging as X-rays; that number is a convention, and the true value is higher where the beam stops.
Overview
Relative biological effectiveness is the photon dose divided by the particle dose that produces the same biological effect. Clinical proton therapy reports dose as Gy(RBE) using a constant 1.1 (ICRU 78). Laboratory and modelling work show RBE rising above 1.1 at the distal edge, where linear energy transfer is highest, which can put extra biological dose in tissue just beyond the target. Carbon-ion therapy uses higher, model-dependent RBE (often around 2 to 3; local effect model or microdosimetric kinetic model). RBE depends on endpoint, dose per fraction, and the tissue's alpha/beta ratio: late-responding tissues with low alpha/beta are more sensitive to high-LET increments. Constant 1.1 is a reporting rule, not a measurement.
- Proton beam
- Bragg peak
- No exit dose
Showing the technology this term belongs to: Proton therapy.
Similar pages
not linked directly; found by shared links- TechnologyProton arc therapy
Shares Bragg peak, Pencil-beam scanning and intensity-modulated proton therapy, Radiotherapy roadmap: X-rays → shaped beams → fewer fractions, particles and FLASH, Proton therapy.
- TechnologyTumour control and normal tissue complication probability (TCP and NTCP)
Shares Biologically effective dose (BED) and EQD2, The linear-quadratic model and fractionation, IMRT / IGRT (modern external beam).
- TechnologyVery-high-energy electron therapy
Shares Carbon-ion therapy, Radiotherapy roadmap: X-rays → shaped beams → fewer fractions, particles and FLASH, Proton therapy, IMRT / IGRT (modern external beam).
- PersonJürgen Debus
Shares Pooled coverage-with-evidence for proton therapy across all centres, Carbon-ion therapy, Proton therapy.
- TechnologyBoron neutron capture therapy
Shares Oxygen enhancement ratio, Linear energy transfer (LET), Radiotherapy roadmap: X-rays → shaped beams → fewer fractions, particles and FLASH.
- CompanyMevion Medical Systems
Shares Pooled coverage-with-evidence for proton therapy across all centres, Radiotherapy roadmap: X-rays → shaped beams → fewer fractions, particles and FLASH, Proton therapy.
- CompanyLeo Cancer Care
Shares Radiotherapy roadmap: X-rays → shaped beams → fewer fractions, particles and FLASH, Proton therapy, IMRT / IGRT (modern external beam).
- TechnologyHypofractionated radiotherapy
Shares Biologically effective dose (BED) and EQD2, The linear-quadratic model and fractionation, Alpha/beta ratio, IMRT / IGRT (modern external beam).