Angular independent silicon detector for dosimetry in external beam radiotherapy

Area of Science:

• Medical Physics
• Radiation Detection
• Semiconductor Devices

Background:

• Traditional silicon detectors can exhibit angular dependence, complicating accurate dose measurements in radiotherapy.
• Developing detectors with negligible angular response is crucial for precise in vivo dosimetry and large-area 2D arrays.

Purpose of the Study:

• To investigate the
• edgeless
• silicon detector technology with innovative packaging for negligible angular response.
• To characterize these detectors as dosimeters for radiotherapy, assessing their suitability for in vivo and 2D array applications.

Main Methods:

• Manufactured
• edgeless-drop-in
• silicon diodes with varying dimensions and junction configurations.
• Tested detectors for percentage depth dose (PDD), dose rate, linearity, output factor, and angular response.
• Assessed radiation hardness and damage effects using Co-60 gamma irradiation up to 40 kGy.

Main Results:

• Detectors achieved agreement within ±2% with ion chambers for PDD and within 2% with film for output factors.
• Diodes on p-type substrates showed dose rate dependence within -7% to +300%, with 5%-15% degradation after 40 kGy.
• Minimal angular response (within 2%) was observed, with P-on-P configurations showing ±1.0% dependence, maintained even after high irradiation doses.

Conclusions:

• A novel
• edgeless-drop-in
• silicon diode technology provides detectors with negligible angular dependence for radiotherapy dosimetry.
• P-on-P detectors with
• drop-in
• packaging are recommended for further development as single probes or 2D arrays due to their superior performance and radiation stability.