Dose verification with EPR/alanine dosimeters in Helical Tomotherapy Stereotactic Radiosurgery (HT SRS) treatments

Intracranial stereotactic radiosurgery (SRS) is a technique to deliver an ablative radiation dose with an extremely sharp dose gradient to small brain tumors. This tecnique allows to deliver high doses of radiation to the tumor sparing the surrounding healthy tissue. In this study the accuracy of the dose delivered in a SRS session by a non conventional radiotherapy machine, the TomoTherapy Hi-Art System, was investigated using an "end-to-end" test. This is perfome d by means of alanine Electron Paramagnetic Resonance (EPR) pe llets. The response of these dosimeters is compared to that of gafchromic films which are particularly suitable for two-dimensional dose verification providing accurate estimate of the distribution and of the gradients of the absorbed dose.