| Popis: |
BACKGROUND: Tumor Treating Fields (TTFields) are low intensity, alternating electric fields approved for treating glioblastoma. In glioblastoma patients, TTFields are delivered via insulated ceramic transducer arrays applied to the scalp. Preclinical data suggest synergistic effects of simultaneous treatment with radiation and TTFields, which may be applicable clinically. Therefore, we investigated the technical issues involved in simultaneously combining TTFields with radiation using a Geant4 simulation. METHODS: The Geant4 simulation of a linear accelerator and the ongoing processes in the irradiation with 6 MV photons was extended by implementation of an electric field, which could be switched on within the used phantom. The alternating electric fields were approximated by constant electric fields. Irradiation with 6 MV photons was simulated with and without an electric field in the phantom. The resulting dose distributions in the phantom were compared with each other to identify any influence on the secondary electrons by the electric field. RESULTS: The implementation of the electric field was successfully validated. Electrical field strengths in the range of the TTFields (2 V/cm) in the direction of irradiation and perpendicular to the direction of irradiation did not show any significant changes in the dose distributions. A shift in the position of the maximum of the depth dose curve could only be observed at electric field intensities of 2 MV/cm, which is 10(6)-times the field intensity of TTFields applied in a clinical setting. CONCLUSION: Regarding the influence of the photon irradiation by TTFields on the secondary electrons, a simultaneous application of both therapies seems feasible. Other aspects of simultaneous therapy remain to be explored. The information obtained by three-dimensional simulation contributes to a better understanding of the simultaneous treatment with TTFields and photon irradiation. In conclusion, simulations suggest that applying TTFields during radiation does not influence the dose distribution and is safe. |
