Technical Note: Characterization of the new microSilicon diode detector.

Area of Science:

• Medical Physics
• Radiation Dosimetry
• Radiotherapy Physics

Background:

• Accurate dosimetry is critical in radiation therapy, especially for small fields where detector size and response can significantly impact dose delivery.
• New detector technologies are continuously developed to improve measurement accuracy and reduce uncertainties in clinical applications.

Purpose of the Study:

• To evaluate the dosimetric properties of the new microSilicon diode detector (60023) for small-field dosimetry.
• To compare the microSilicon detector's performance with its predecessor (Diode E 60017) and the microDiamond (60019).

Main Methods:

• Investigated dose linearity and dose-per-pulse dependence.
• Determined the effective point of measurement (EPOM) by comparing depth dose curves.
• Measured output ratios and derived small-field output correction factors (k) using a plastic scintillation detector as reference.
• Assessed the lateral dose-response function (K(x)) using a slit beam geometry.

Main Results:

• MicroSilicon demonstrated excellent dose linearity (R² = 1.000) up to 8.55 Gy with minimal dose-per-pulse dependence.
• The EPOM was located at (0.7 ± 0.2) mm below the front detector surface.
• MicroSilicon's derived correction factor (k=0.960) was similar to microDiamond (0.956) and superior to Diode E (0.929), indicating better performance in small fields.
• Lateral dose-response function (K(x)) showed reduced perturbation compared to Diode E.

Conclusions:

• MicroSilicon exhibits superior dosimetric behavior, including higher sensitivity and reduced dose-per-pulse dependence compared to its predecessor.
• The detector causes less perturbation in off-axis measurements, making it highly suitable for small-field output factor and profile measurements in radiotherapy.