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Note on TPS dose reporting (MV beams)
Reference dosimetry: dose to a small water element
w
embedded at depth
z
in a large water phantom:
z
e
D
w
o
wen,
Ww,
µ−
Ψ
ρ
µ
≅
Assuming that cell nuclei is water (ICRU 83)
i.e. dose to a small water element w embedded in a
phantom of medium M:
w
m
o
men,
Mw,
m
Ψ ≅
−
ρ
ρ
µ
µ
S
e
D
z
approx. equations:
:
Ψ
0
Dose to the medium in the medium:
z
e
D
m
o
men,
Mm,
µ−
Ψ
ρ
µ
≅
w
m
Mm,
Mw,
=
ρ
S
D D
⇒
conversion of dose to medium to dose to water
from Anders Ahnesjö