KEY POINTS
- Investigators independently evaluated the unshielded SunSILICON 1048 and shielded SunSILICONP 1049 detectors on a Varian TrueBeam using 6 MV, 6 MV FFF, 10 MV, 10 MV FFF, and 15 MV photon beams.
- Both detectors demonstrated highly linear response across the investigated energies. Signal variation was approximately 2% below 3 MU and about 0.5% above 3 MU, with high measurement reproducibility.
- Dose-rate dependence remained small from 100 MU/min to the maximum available dose rate, with an approximately 1.5% upward trend at low rates. Temperature dependence was also minimal, remaining below approximately 0.5% from 4°C to 40°C.
- The unshielded 1048 showed good agreement with EGSnrc Monte Carlo calculations for depth dose, profiles, and field-output factors, including fields down to 0.5 × 0.5 cm².
- Its small-field correction factors remained within approximately ±3% over the validated small-field range, placing its performance near established detectors such as microSilicon, microDiamond, plastic scintillators, and radiochromic film.
- The shielded 1049 behaved very differently: signal fell markedly when field size decreased below approximately 2 cm, producing large and strongly field-size-dependent corrections because of perturbation from its high-Z shielding.
- Angular dependence was not measured directly, and the noncylindrical detector housing can complicate use in solid phantoms by introducing air gaps. The authors therefore favour the unshielded detector for small fields and the shielded model for conventional medium-to-large photon fields.
CLINICAL TAKEAWAY
The two physically similar SunSILICON detectors should not be treated as interchangeable. The unshielded 1048 appears well suited to small-field photon dosimetry, whereas the shielded 1049 should generally be avoided when lateral charged-particle equilibrium is lost.