First Clinical Experience of Tungsten Rubber Electron Adaptive Therapy With Real-time Variable-shape Tungsten Rubber.

Background/aim: We investigated the dosimetric characteristics of electron radiotherapy for auricular keloid using real-time variable-shape tungsten rubber (STR).

Patients And Methods: For the first evaluation, STR was shaped into a rectangular irradiation field (3.0×5.0 cm). In the next step, the STR was reshaped to fit the target (3.5×6.5 cm) for the second evaluation. Percentage depth doses (PDDs) and lateral dose profiles were obtained with 6-MeV electron beams and compared with those of low-melting-point lead (LML).

Results: Compared to the LML on electron applicator, PDD differences were within 0.4 mm, while the penumbras as width of 20-80% dose levels were smaller (maximum reductions: 75.8% and 82.9% at first and second evaluations, respectively). The treatment process of shaping the STR, decision on output, and irradiation was completed within 45 min.

Conclusion: Electron radiotherapy using STR for keloid can be performed with excellent dose distribution in a short time. First clinical experience found the STR is suitable for use in individualized and immediate electron radiotherapy.