Table 1.

Overview of types of radiation.

Type of Radiation	Particle	Mass	Typical Energy	Typical Range in Tissue	LET (keV/µm)	RBE
Alpha	2 protons and 2 neutrons	6.6 × 10−27 kg	Discrete; ~4–10 MeV	~20–70 µm	~50–300	~5
Beta minus	Electron	9.1 × 10−31 kg	Continuous; maximum of some hundred keV to some MeV	Less than a mm to some mm	~0.1–2	~1
Auger	Electron	9.1 × 10−31 kg	<10 keV	<1 µm	~4–26	~1 or higher