clinical electron beam characteristics

Clinical Electron beam characteristics : 

Clinical Electron beam characteristics p.Senthil kumar m.sc(medical physics)‏

Linear accelerator head : 

Linear accelerator head

Electron source : 

Electron source

Slide 4: 

Central axis depth dose

Absorbed dose build-up : 

Absorbed dose build-up

Slide 6: 

Absorbed dose at surface Depth in water in cm

Slide 7: 

Isodose curves

Range concept : 

Range concept

Electron beam energy specification : 

Electron beam energy specification The most probable energy Ep,0 Ep,0 = 0.22 + 1.09Rp + 0.0025Rp ² The mean electron energy E0 E0¯ = CR50 where C = 2.33 MeV/cm for water. Ez, the mean energy at a depth z in a water phantom, is related to the practical range Rp by the Harder equation as follows Ez = E0 (1 – z/Rp)‏

Slide 10: 

TYPICAL DEPTH DOSE PARAMETERS OF ELECTRON BEAMS Energy R90 R80 R50 Rp E0 Surface dose (MeV) (cm) (cm) (cm) (cm) (MeV) (%)‏ 6 1.7 1.8 2.2 2.9 5.6 81 8 2.4 2.6 3.0 4.0 7.2 83 10 3.1 3.3 3.9 4.8 9.2 86 12 3.7 4.1 4.8 6.0 11.3 90 15 4.7 5.2 6.1 7.5 14.0 92 18 5.5 5.9 7.3 9.1 17.4 96

Field size dependence : 

Field size dependence

Back scattering of electrons : 

Back scattering of electrons

Field shaping : 

Field shaping Electron beam applicators Shielding and cut-outs

Electron applicators : 

Electron applicators

Slide 15: 

Shielding and cut-outs LEAD THICKNESS (mm) REQUIRED FOR VARIOUS TRANSMISSION LEVELS FOR A 12.5 × 12.5 cm2 ELECTRON FIELD Energy (MeV)‏ Transmission (%) 6 8 10 12 14 17 20 50 1.2 1.8 2.2 2.6 2.9 3.8 4.4 10 2.1 2.8 3.5 4.1 5.0 7.0 9.0 5 3.0 3.7 4.5 5.6 7.0 8.0 10.0

Clinical applications of electron beam therapy : 

Clinical applications of electron beam therapy

Slide 17: 

Thank you