446 / 1359
7
0
0
E
=
0
e
z
−
en
0
e
z
−
0
e
z
−
en
0
e
z
−
−
Incident energy fluence
Attenuated energy fluence at depth
z
Energy/mass ”taken away” from the direct beam, TERMA, at depth
z
Energy/mass transfered into collision KERMA at
z
, appr.
Primary Dose
Energy/mass transfered into photon scatter, SCERMA, at depth
z
Primary Photon beam energy balance
0
z
TERMA, Total Energy Released per MAss
KERMA, Kinetic Energy Released per MAss
SCERMA, photon Scatter Energy Released per MAss
Collision KERMA+SCERMA=TERMA