TY - JOUR
T1 - Comparison of ionisation measurements in water and polystyrene for electron beam dosimetry
AU - Bruinvis, I. A.D.
AU - Heukelom, S.
AU - Mijnheer, B. J.
PY - 1985/1/1
Y1 - 1985/1/1
N2 - For the determination of absorbed dose to water in electron beams, dosimetry protocols advocate ionisation measurements in plastic phantoms instead of water for practical reasons. The chamber readings in polystyrene at the depth of maximum ionisation must be corrected for the difference in physical properties between the two materials. This correction factor was determined for a Farmer 0.6 cm3 graphite-walled chamber in electron beams with mean energies at the phantom surface between 6 and 19 MeV. Experiments with white polystyrene yielded corrections for the measured ionisation ranging from 0.3 to 2.4%. For clear polystyrene, 0.6-1% higher corrections were found. For beams with the same mean energy at the phantom surface, but with different beam-flattening and collimation systems, variations in this correction up to 1.2% were observed. In contrast to recent reports on electrical charge storage in polystyrene due to electron irradiation, the authors' experiments do not show differences in the chamber readings any larger than 0.5%.
AB - For the determination of absorbed dose to water in electron beams, dosimetry protocols advocate ionisation measurements in plastic phantoms instead of water for practical reasons. The chamber readings in polystyrene at the depth of maximum ionisation must be corrected for the difference in physical properties between the two materials. This correction factor was determined for a Farmer 0.6 cm3 graphite-walled chamber in electron beams with mean energies at the phantom surface between 6 and 19 MeV. Experiments with white polystyrene yielded corrections for the measured ionisation ranging from 0.3 to 2.4%. For clear polystyrene, 0.6-1% higher corrections were found. For beams with the same mean energy at the phantom surface, but with different beam-flattening and collimation systems, variations in this correction up to 1.2% were observed. In contrast to recent reports on electrical charge storage in polystyrene due to electron irradiation, the authors' experiments do not show differences in the chamber readings any larger than 0.5%.
UR - http://www.scopus.com/inward/record.url?scp=0021932405&partnerID=8YFLogxK
U2 - 10.1088/0031-9155/30/10/003
DO - 10.1088/0031-9155/30/10/003
M3 - Article
C2 - 4070361
AN - SCOPUS:0021932405
VL - 30
SP - 1043
EP - 1053
JO - Physics in Medicine and Biology
JF - Physics in Medicine and Biology
SN - 0031-9155
IS - 10
M1 - 003
ER -