| Background: Recent advances in modern radiotherapy techniques such as Intensity-Modulated Radiation Therapy (IMRT) and Stereotactic Radiosurgery (SRS) have significantly increased the need for accurate and reliable dosimetry in radiation therapy. Accurate dose delivery is particularly critical in small electron fields, which are increasingly used in targeted treatments. However, these fields pose unique challenges due to factors such as electron disequilibrium, increased lateral scatter, and steep dose gradients. These physical characteristics can introduce significant uncertainties in dose distribution, thereby reducing the effectiveness and safety of the treatment if not properly accounted for. Traditional dosimeters often struggle to maintain accuracy under such conditions. The aim of this study was to evaluate the performance of MAGIC polymer gel as a three-dimensional (3D) dosimeter in small electron fields and to compare its dosimetric characteristics with standard dosimeters including diode, semiflex, and pinpoint.
Methods: This experimental and applied study was conducted at the Radiotherapy Department of Imam Reza Hospital, Kermanshah, Iran, over a one-year period from December 2022 to December 2023. Five electron field sizes (2×2, 2.5×2.5, 3×3, 4×4, and 5×5 cm²) were generated using an Elekta linear accelerator at two electron beam energies of 6 and 9 MeV. MAGIC polymer gel phantoms were irradiated accordingly and scanned with a 1.5 Tesla MRI system to obtain three-dimensional dose distributions. These were compared to measurements obtained from diode, semiflex, and pinpoint dosimeters.
Results: The depth dose curves of MAGIC gel exhibited greater agreement with diode measurements compared to those from semiflex and pinpoint detectors. As field size decreased and beam energy increased, discrepancies in absorbed dose readings between different dosimeters became more apparent. These results underscore the importance of selecting appropriate dosimetric tools for accurate dose evaluation in small-field electron beams.
Conclusion: MAGIC polymer gel demonstrated strong potential as a reliable 3D dosimeter for small electron field dosimetry, showing the highest compatibility with the diode dosimeter. |