Background: Although the dosimetric properties of synthetic single crystal diamonds make these detectors well suitable for precise dosimetry, to the best of our knowledge the angular response of these dosimeters irradiated with very high dose-per-pulse electron beams has never been investigated before. Material and Methods: A PTW microDiamond (type 60019) was inserted in a home-made spherical phantom filled with water. The sensitive volume was placed at the center (depth = 2 cm). The angular dependence of the detector was evaluated in IORT electron beams produced by a mobile accelerator (LIAC) with energies of 6, 8, 10 and 12 MeV. A total of 48 measurements were performed rotating the accelerator treatment head at 0°, 15°, 30° and 45° and using 3 flat collimators (4, 5 and 10 cm). Then, 78 output factors (OFs) of flat and bevelled IORT applicators were measured and compared to Monte Carlo simulations. For bevelled applicators, correction factors were calculated from the directional response of the microDiamond and applied to the measured OFs. Preliminary Results: The microDiamond showed a higher variation in the directional response for the 6 MeV beam (8.2%, range 91.8% ÷ 100.0%) with the largest deviation at 45° and the 10 cm collimator. The variations for 8, 10 and 12 MeV beams were respectively 4.3%, 3.4% and 3.5% (range 96.6% ÷ 101.0%). For flat applicators, the average deviation between measured and simulated OFs was (-1.1 ± 0.7)%. Correcting for the angular dependence of the microDiamond, the OFs average deviation for bevelled applicators was (-0.9 ± 1.6)%. Due to the large variation in the directional response of the microDiamond to the beam incidence angle, a correction must be applied for the OF determination of bevelled applicators. Very similar deviations were found between flat and bevelled applicators, confirming the suitability of our method to determine the angular correction factors of the detector.
DETERMINATIO OF THE ANGULAR RESPONSE OF A SINGLE CRYSTAL DIAMOND DETECTOR IN VERY HIGH DOSE-PER-PULSE IORT ELECTRON BEAMS
K. E. Szilagyi;E. De Guglielmo;S. Fabbri;F. Calderoni;A. Stefanelli;G. Di Domenico;A. Turra
2023
Abstract
Background: Although the dosimetric properties of synthetic single crystal diamonds make these detectors well suitable for precise dosimetry, to the best of our knowledge the angular response of these dosimeters irradiated with very high dose-per-pulse electron beams has never been investigated before. Material and Methods: A PTW microDiamond (type 60019) was inserted in a home-made spherical phantom filled with water. The sensitive volume was placed at the center (depth = 2 cm). The angular dependence of the detector was evaluated in IORT electron beams produced by a mobile accelerator (LIAC) with energies of 6, 8, 10 and 12 MeV. A total of 48 measurements were performed rotating the accelerator treatment head at 0°, 15°, 30° and 45° and using 3 flat collimators (4, 5 and 10 cm). Then, 78 output factors (OFs) of flat and bevelled IORT applicators were measured and compared to Monte Carlo simulations. For bevelled applicators, correction factors were calculated from the directional response of the microDiamond and applied to the measured OFs. Preliminary Results: The microDiamond showed a higher variation in the directional response for the 6 MeV beam (8.2%, range 91.8% ÷ 100.0%) with the largest deviation at 45° and the 10 cm collimator. The variations for 8, 10 and 12 MeV beams were respectively 4.3%, 3.4% and 3.5% (range 96.6% ÷ 101.0%). For flat applicators, the average deviation between measured and simulated OFs was (-1.1 ± 0.7)%. Correcting for the angular dependence of the microDiamond, the OFs average deviation for bevelled applicators was (-0.9 ± 1.6)%. Due to the large variation in the directional response of the microDiamond to the beam incidence angle, a correction must be applied for the OF determination of bevelled applicators. Very similar deviations were found between flat and bevelled applicators, confirming the suitability of our method to determine the angular correction factors of the detector.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
