Purpose: The present study evaluated the clinical feasibility of the amorphous silicon (a-Si) based flexible thin film solar cell coated with scintillating powder for in vivo dosimetry for electron beam therapy.
Methods: Scintillating powder was coated on a thin film solar cell using an optical adhesive to enhance the sensitivity of in vivo dosimetry system. Calibration factors of this system was acquired by dividing the dose measured at a reference depth for 6-20 MeV electron beam energy using the Markus chamber which was used as reference chamber and the signal measured using solar cell under the same condition. Energy dependence, source-to-surface distance (SSD) dependence, angular dependence and dose linearity of this system were evaluated. Also, surface doses measured using solar cell in vivo dosimetry system, Markus chamber, and thermoluminescent dosimeter (TLD) were compared to evaluate the feasibility of thin film solar cell for in vivo dosimetry for electron beam therapy.
Results: The signals generated through interaction between solar cell and electron beam increased linearly with absorbed dose and were independent to electron energy, SSD and beam angle. Calibration factors for each electron beam energy were verified through comparison between the dose calculated using solar cell and that measured using Markus chamber at R90. The dose difference between the solar cell and the Markus chamber was less than 5%, while the dose measured using TLD showed a difference of about 7%.
Conclusion: Clinical feasibility of the a-Si flexible thin film solar cell based real-time in vivo dosimetry system for electron beam therapy was evaluated by comparing the surface dose measured using this system with those measured using Markus chamber and TLD. The results in this study suggest that this system has the potential for in vivo dosimetry of electron beam therapy.