Characterization of two new unshielded and shielded silicon diode detectors for external beam radiation therapy:...

Radiation dosimeters are essential for measuring beam characteristics in external beam radiotherapy. While ionization chambers are widely used, they have limitations such as large active volumes or small signal strengths. Silicon diodes, with their high density and low mean energy required to generate electron-hole pairs, offer superior spatial resolution and sensitivity.

This study aims to evaluate the characteristics of a newly developed silicon diode embedded in SunSILICON and SunSILICON P for relative dosimetry in external beam radiotherapy.

The evaluation involved fundamental tests such as reproducibility, linearity with dose, and speed of response. Critical aspects like impedance and leakage characteristics, accumulated dose dependency, temperature dependency, pulse repetition frequency dependence, and instantaneous dose rate dependency were also assessed. Measurements were performed using a Varian TrueBeam clinical linear accelerator and ⁶⁰Co, with most tests conducted in water equivalent HE Solid Water slab phantoms.

The SunSILICON and SunSILICON P detectors demonstrated a linear response, and the dose rate dependence of the response was below 1 %, even for pre-conditioned detectors. The detectors showed a near-instantaneous response to radiation. The diode features a high signal-to-noise ratio and low leakage. The temperature dependence of the response was 0.06 %/K, and the accumulated dose dependence was less than 0.1 %/kGy for 6 MV photons.

The SunSILICON and SunSILICON P detectors exhibit excellent characteristics for clinical use in external beam radiation therapy. Their high sensitivity, low noise, and minimal dose rate and temperature dependencies make them reliable tools for accurate dosimetry. These results provide a foundation for further clinical evaluation and validation of these detectors.