Three-Dimensional Diose-Based Dose Profiling for Gamma Knife Collimators Using a 3D-Printed Detector Holder
Abstract
Purpose
Accurate small-field dosimetry for stereotactic radiosurgery is challenging due to steep dose gradients and detector positioning limitations. This study evaluates the feasibility of using a high-resolution diode detector, secured within a custom 3D-printed holder, to acquire three-dimensional dose profiles for Gamma Knife collimators and compares these measurements with film-based reference data.
Methods
Three-dimensional dose profile measurements were performed using a semiconductor diode detector (TN60016) mounted in a custom-designed 3D-printed holder to ensure reproducible detector positioning. Measurements were acquired for 4 mm, 8 mm, and 16 mm Gamma Knife collimators. Dose profiles were measured along the X, Y, and Z axes with a step size of 1 mm. For each measurement, the scanning axis was varied from 70 mm to 130 mm while the remaining two axes were held constant at 100 mm. Each spatial direction was scanned independently to maintain consistent geometry. Measured profiles were normalized by averaging values near the peak dose region to define a representative maximum. Diode-measured profiles were qualitatively compared with film-based dose distributions acquired under similar conditions.
Results
Diode-measured dose profiles demonstrated strong agreement with film-based reference data for all collimator sizes and measurement directions. Profile shape, symmetry, and field width characteristics were visually consistent between measurement techniques. The 4 mm collimator exhibited steep dose gradients that were well resolved by the diode detector, while the 8 mm and 16 mm collimators showed smooth and symmetric profiles across all spatial axes.
Conclusion
Preliminary results indicate that high-resolution diode detectors mounted in a reproducible 3D-printed holder can accurately measure three-dimensional dose profiles for Gamma Knife collimators, demonstrating good agreement with film-based data. This approach shows promise as an efficient alternative for small-field stereotactic radiosurgery quality assurance, with ongoing work extending the methodology to additional diode detectors.