In this study, experimentally and theoretically determined absorbed dose to water calibration factors were compared. We used 6 MV photon and 12 MeV electron energies to compare experimentally and theoretically determined beam quality dependence factors.
METHODS
Measurements were made at SSD=100 cm distance (L IN
A C), 10x10 cm standard field size and reference depth.
Five different cylindrical and three parallel plate chambers
were used.
RESULTS
For absorbed dose to water calibration factor, the max difference
between theoretical and experimental values was 2.8%
for Marcus chamber. Beam quality dependence factors for 6
MV theoretical values of PTW 30001 (a) (-0.816%), NE 2571
(-0.1107%) were greater than their experimental values. For
12 MeV, the difference was 1.2371% for PTW 30001 (a),
1.6774% for PTW 30001 (b), 0.8758% for NE 2571, 0.8363%
for NE 2581, 0.6071% for PTW 30002, and 0.6245% for
Marcus ion chamber.
CONCLUSION
As the protocol suggests, obtaining absorbed dose to water
calibration factor directly from SSDL produces more accurate
results.