ESTRO 2024 - Abstract Book

S3354

Physics - Detectors, dose measurement and phantoms

ESTRO 2024

Figure 1: Measured (right) and simulated (left) profile of the 3 mm cone

Conclusion:

Our study demonstrated that the new 3 mm collimate cone can be characterized with a microSilicon detector. The profiles as well as the output factors measured with the microSilicon detector and film agree within the associated uncertainty. Both the measurements and Monte Carlo simulations showed that the volume-averaging effect due to the 1.5 mm sensitive volume in diameter causes a small but observable profile broadening of the 3 mm beam profile. This is in accordance with the Monte Carlo study of the perturbation effects associated with the microSilicon detector, where the volume-averaging effect, although partially compensated by the density perturbation caused by the detector’s material, is more dominant causing the microSilicon to under respond in the 3 mm field. Nevertheless, the associated output correction is less than the 5% limit as recommended by the TRS 483.

Keywords: small field dosimetry, radiosurgery, microSilicon

References:

[1] Delfs, B., Blum, I., Tekin, T., Schönfeld, A. B., Kranzer, R., Poppinga, D., Giesen, U., Langner, F., Kapsch, R. P., & Poppe, B. (2021). The role of the construction and sensitive volume of compact ionization chambers on the magnetic field ‐ dependent dose response. Medical Physics, 48(8), 4572-4585. [2] Blum, I., Tekin, T., Delfs, B., Schönfeld, A.-B., Kapsch, R.-P., Poppe, B., & Looe, H. K. (2021). The dose response of PTW microDiamond and microSilicon in transverse magnetic field under small field conditions. Physics in Medicine & Biology, 66(15), 155003. [3] Weber, C., Kranzer, R., Weidner, J., Kröninger, K., Poppe, B., Looe, H. K., & Poppinga, D. (2020). Small field output correction factors of the microSilicon detector and a deeper understanding of their origin by quantifying perturbation factors. Medical Physics, 47(7), 3165-3173.