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

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

For the first evaluation, STR was shaped into a rectangular irradiation field (3.0×5.0 cm²). In the next step, the STR was reshaped to fit the target (3.5×6.5 cm²) 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).

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.

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.