Application of dose gels in HDR brachytherapy

Abstract

Normoxic gels are frequently used in clinical praxis for dose assessment or 3D dose imaging in radiotherapy due to their relative simple manufacturing process, well expressed radiation induced modification of physical properties and well defined spatial shape of the polymerized gel part in the irradiated volume. Normoxic polyacrylamide (nPAG) gels were irradiated in high dose rate (HDR) after loading brachytherapy system MicroSelectron v2 with192Ir source. The source was inserted into 6 Fr catheter which was fixed at the axial position of the gel filled beaker during gel preparation phase. Varying composition and manufacturing process conditions free standing polymerized gel shapes were produced around a catheter as polymerization center. Dose and dose rate related properties of the free standing polymerized gel shapes were evaluated using Raman spectroscopy and were compared to those of in the gel volume located polymerized gel regions of usual nPAG gels. Analysis of the obtained results is provided and possibility to pre-assess special dose distribution in the prescribed irradiation target using these free standing polymerized gels is discussed.