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D
w,Co
= D
air,Co
(s
w,air
)
Co
D
air,Co
= (Q
W
air,Co
)/m
- Q = charge formed in air cavity (measured with electrometer)
- W
air,Co
= average energy expended in air per coulomb
- m = mass of air in cavity
D
w,Co
= ((Q
W
air,Co
)/m)
(s
w,air
)
Co
standard dosimetry: dose measurement with i.c. in
60
Co:
TRS398:
- W
air,Co
= 33.97 J/C
- (s
w,air
)
Co
= 1.134
used in standard laboratory to assess dose with their
ionometric standard:
D
w,Co
= ((Q
W
air,Co
)/m)
(s
w,air
)
Co
f
i
Refinements needed e.g. to correct
for deviations Bragg-Gray (in TRS398)
D
air,Co
= E
air,Co
/m, E
air,Co
is energy deposited in air by electrons
air
water
P
i.c
Ionometric standard