Dose Course 2018_Flipping book

Some TPS’s 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 e r medium rMV rT 0 ' ' ' ,' , , ,

 

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Primary energy fluence at the surface

Effective (spectrum averaged) mass attenuation coefficient at radiological distance r for the medium with certain density

• 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