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TPS dose engines: common misunderstandings
Why do some TPSs require CT calibration tables in
terms of relative mass density
e.g. in point kernel dose calculation engines it is TERMA and point kernels that are
scaled
r
dr r r
medium rMV
o
e
r
medium rMV
r
T
0
'
'
'
,' ,
, ,
Effective (spectrum averaged) mass attenuation
coefficient at radiological distance r for the
medium with certain density
Primary energy fluence at the surface
•
Mass attenuation coefficients usually pre-stored as weighted averages for an
energy spectrum and for media with different composition and mass density
•
N
CT
relative mass density and material composition
mass attenuation coefficient and linear attenuation coefficient
e.g. in Pinnacle, TomoTherapy PS