Dose Course 2018_Flipping book

Calibration: Entrance dose dose at the depth of dose maximum

Ideal situation :

When changing the irradiation conditions the reading of the in vivo

detector changes in the same proportion as changes the i.c. reading

wedge, SSD, (r, ent D

T)

=

SSD, R(r,

wedge,



calFT)

z max

Reality :

Detector+ build up response dependence in dose rate, energy, temperature may differ of those of an i.c. Due to the calibration geometry the detectors “see” different scatter conditions.