The comparison of absorbed dose measurements for water and artificial body fluid

Advances in radiation dosimetry concepts and the development of primary measurement standards based on absorbed dose to water over the last decades offer the possibility to calibrate ionisation chambers directly in terms of absorbed dose to water. The aim of this study is the investigation on utility of artificial body fluid (ABF) instead of water by comparing dosimetric measurements for radiotherapy between water and ABF which is more close to human tissue. The measurements were done using 60Co gamma source with a radiation field sizes of 5×5, 10×10, 15×15, 20×20 and 25×25 cm2 at PTW Freiburg MP3 water phantom front surface. The comparisons of the dose measurements were obtained by using IAEA TRS-398 dosimetry protocols and Mephysto mc2 dose analyzer program. Percent depth dose (PDD), dose profiles and penumbras are compared for water and ABF. When the results of the PDD for water and ABF were compared, the maximum difference was observed in big field sizes. The difference in penumbras was found 2.3 mm averagely for depth of maximum dose (dmax). In addition same differences were observed between water and ABF when the dose profiles were compared. It is found that PDD values taken for water are good agreed with PDD values published in British Journal of Radiology (BJR) Supplement 25. Since the ABF is more equivalent to human tissue than water, it is suggested that advanced dosimetric studies should be performed with ABF instead of water.