Dosimetric characteristics of water equivalent for two solid water phantoms

Abstract

Objective To investigate the water equivalent of two solid water phantoms.Methods The X-ray and electron beam depth-ion curves were measured in water and two solid water phantoms,RW3 and Virtual Water.The water-equivalency correction factors for the two solid water phantoms were compared.We measured and calculated the range sealing factors and the fluence correction factors for the two solid water phantoms in the case of electron beams. Results The average differenee between the measurled ionization in solid water phantoms and water was 0.42%and 0.16%on 6 MV X-ray(t=-6.15.P=0.001and t=-1.65,P=0.419)and 0.21%and 0.31%on 10 MV X-ray(t=1.728,P=0.135 and t=-2.296,P=0.061),with 17.4%and 14.5%on 6 MeV electron beams(t=-1.37.P=0.208 and t=-1.47,P=0.179)and 7.0%and 6.0%on 15 MeV electron beams(t=-0.58.P=0.581 and t=-0.90,P=0.395).The water-equivalency correction factors for the two solid water Dhantoms varied slightly largely,F=58.54,P=0.000 on 6 MV X-ray,F=0.211.P=0.662 on 10 MV X.ray,F=0.97.P=0.353 on 6 MeV electron beams,F=0.14,P=0.717 on 15 MeV electron beams.However,they were almost equal to 1 near the referenee depths.The two solid water phantoms showed a similar tread of Cpl increasing(F=26.40,P=0.014)and hpl decreasing(F=7.45,P=0.072)with increasing energy.Conclusion The solid water phantom should undergo a quality control test before being clinical use. Key words: SoIid Water phantom; Water equivalent