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Experimental dosimetry:
Use of a detector (dosimeter) providing a measurable signal
that is of a known relationship with the absorbed dose in its volume
•
The relationship between signal and dose is known for absolute dosimeters
(calorimeters, ion chambers & Fricke gels)
•
All other dosimeters must be
calibrated
relative to an absolute one in a beam
quality Q
0
, to obtain the
absorbed dose sensitivity
:
or equivalently the
calibration coefficient
:
•
Dose to a medium in the absence of the detector (water) is of interest
•
The calibration must be traceable to international standards
)
0(
)0
(
)
0( ,
QwD
Q
M
Q
S wAD
=
)0(
)
0(
)0(
,
QM
QwD
QwAD
N
=
* The terminology used in this lecture is that introduced in:
Rogers & Cygler (Eds), Clinical dosimetry measurements in radiotherapy (2009 AAPM Summer School),
Monograph No. 34, Medical Physics Publishing 2011