High spatial resolution dosimetry for radiation oncology with "MagicPlates," a new 976-pixel monolithic silicon detector
- Author(s)
- Filipev, I; Alnaghy, S; Carolan, M; Paino, J; Petasecca, M; Cutajar, D; Poder, J; Davies, JB; Oborn, BM; Hardcastle, N; Guatelli, S; Lerch, M; Kron, T; Rosenfeld, A;
- Journal Title
- Journal of Applied Clinical Medical Physics
- Publication Type
- Online publication before print
- Abstract
- PURPOSE: We introduce the next generation of "MagicPlate" 2D monolithic pixelated semiconductor detectors - MagicPlate-976 (MP976). It features a larger array area, higher spatial resolution, and does not require external triggering. We perform a comprehensive characterization for small-field steep-dose-gradient dosimetry applications in radiation therapy focusing on x-ray beams used in stereotactic treatments. METHODS: The MP976, developed by the Centre for Medical Radiation Physics, consists of 976 ion-implanted diodes on a thin n-type epitaxial silicon substrate with a total array area of 58 × 58 mm(2). The central region has "small" diodes with an area of 0.2 × 0.2 mm(2) and 1 mm pitch and the peripheral region has "large" diodes with an area of 0.6 × 0.6 mm(2) and 2 mm pitch. The detector was primed with 10 kGy (Co-60) and tested using a Varian TrueBeam linear accelerator for sensitivity change and dose linearity, and variations in response due to dose-per-pulse and beam incidence angle. Output factors, depth dose, and beam profiles were measured and compared with reference data. RESULTS: After the 10 kGy, the sensitivity declined by (74 ± 5)% for "large" diodes and by (78 ± 7)% for the "small" ones, the dose-per-pulse (DPP) dependence was in the range of commercially available diodes, however, a difference in the DPP dependence between the "large" and "small" diodes of (8.4 ± 0.2)% was found in the studied DPP range from 0.131-1.111 mGy/pulse. The minimum angular response was at 90° for 6 MV and 100° for 10 MV flattened beams (76% and 82%, respectively). The output factors and depth dose response showed agreement with the reference within 3.1% and 1%, respectively. Deviation in small field 80%/20% penumbra measurements was within 0.5 mm for 6 MV FF and 0.3 mm for 10 MV FFF. Full width at half maximum (FWHM) for the beam profiles agreed within 0.5 mm for both beam qualities. CONCLUSION: The new MagicPlate-976 detector system is shown to be suitable for dosimetry in small fields and steep dose gradients. It provides 1 mm spatial resolution in the central region and 2 mm on the periphery and has no dependence on the field size. The system's high spatial and temporal resolution opens new opportunities for trigger-less, film-less, and time-resolved verification and error identification for complex stereotactic treatment plans.
- Publisher
- Wiley
- Keywords
- high spatial resolution; monolithic 2D array; silicon pixelated detector; small field dosimetry; stereotactic radiotherapy
- Department(s)
- Physical Sciences
- Publisher's Version
- https://doi.org/10.1002/acm2.70015
- Open Access at Publisher's Site
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Creation Date: 2025-04-03 02:22:06
Last Modified: 2025-04-03 02:22:33