A 2D silicon detector array for quality assurance in small field dosimetry: DUO

Area of Science:

• Medical Physics
• Radiation Oncology
• Detector Technology

Background:

• Small field dosimetry in radiotherapy presents challenges like lateral disequilibrium and source occlusion.
• Accurate quality assurance (QA) is crucial for small field radiotherapy treatments.
• Existing silicon diode arrays often lack the necessary spatial resolution for small field dosimetry.

Purpose of the Study:

• To characterize the DUO monolithic silicon diode array for dosimetry QA in stereotactic radiosurgery/stereotactic radiotherapy (SRS/SRT).
• To evaluate the DUO detector's performance in small radiation fields, focusing on its high spatial resolution (0.2 mm pitch).

Main Methods:

• The DUO detector, comprising two orthogonal 1D silicon arrays with 0.2 mm pitch, was tested.
• Characterization included dose per pulse, percentage depth dose, and spatial resolution measurements.
• Comparisons were made with EBT3 films and ionization chambers for beam profiles and output factors.

Main Results:

• DUO demonstrated dose per pulse stability within 5% across a range of dose rates.
• Percentage depth dose measurements agreed within 1.5% with a Markus ionization chamber.
• Beam profiles showed excellent agreement with EBT3 films (FWHM within 1%, penumbra within 0.5 mm).
• Output factors for small fields agreed within 1.8% with EBT3 films and MOSkin detectors.

Conclusions:

• The DUO monolithic silicon detector array is well-suited for SRS/SRT dosimetry and QA.
• Its high spatial resolution and real-time operation address limitations of previous detectors.
• DUO facilitates accurate measurements in high-gradient radiation fields.