A Skrobala1, S Adamczyk2, M Kruszyna-Mochalska3, M Skórska2, A Konefał4, W Suchorska5, K Zaleska5, A Kowalik2, W Jackowiak6, J Malicki3. 1. Electroradiology Department, University of Medical Sciences, Poznan, Poland; Medical Physics Department, Greater Poland Cancer Centre, Poznan, Poland. Electronic address: agnieszka.skrobala@wco.pl. 2. Medical Physics Department, Greater Poland Cancer Centre, Poznan, Poland. 3. Electroradiology Department, University of Medical Sciences, Poznan, Poland; Medical Physics Department, Greater Poland Cancer Centre, Poznan, Poland. 4. Department of Nuclear Physics and its Applications, Institute of Physics, Silesian University, Katowice, Poland. 5. Radiobiology Laboratories, Medical Physics Department, Greater Poland Cancer Centre, Poznan, Poland. 6. Ist Radiotherapy Department, Greater Poland Cancer Centre, Poznan, Poland.
Abstract
PURPOSE: During radiotherapy, leakage from the machine head and collimator expose patients to out-of-field irradiation doses, which may cause secondary cancers. To quantify the risks of secondary cancers due to out-of-field doses, it is first necessary to measure these doses. Since most dosimeters are energy-dependent, it is essential to first determine the type of photon energy spectrum in the out-of-field area. The aim of this study was to determine the mean photon energy values for the out-of-field photon energy spectrum for a 6 MV photon beam using the GEANT 4-Monte Carlo method. MATERIAL AND METHODS: A specially-designed large water phantom was simulated with a static field at gantry 0°. The source-to-surface distance was 92cm for an open field size of 10×10cm2. The photon energy spectra were calculated at five unique positions (at depths of 0.5, 1.6, 4, 6, 8, and 10cm) along the central beam axis and at six different off-axis distances. RESULTS: Monte Carlo simulations showed that mean radiation energy levels drop rapidly beyond the edge of the 6 MV photon beam field: at a distance of 10cm, the mean energy level is close to 0.3MeV versus 1.5MeV at the central beam axis. In some cases, the energy level actually increased even as the distance from the field edge increased: at a depth of 1.6cm and 15cm off-axis, the mean energy level was 0.205MeV versus 0.252MeV at 20cm off-axis. CONCLUSION: The out-of-field energy spectra and dose distribution data obtained in this study with Monte Carlo methods can be used to calibrate dosimeters to measure out-of-field radiation from 6MV photons.
PURPOSE: During radiotherapy, leakage from the machine head and collimator expose patients to out-of-field irradiation doses, which may cause secondary cancers. To quantify the risks of secondary cancers due to out-of-field doses, it is first necessary to measure these doses. Since most dosimeters are energy-dependent, it is essential to first determine the type of photon energy spectrum in the out-of-field area. The aim of this study was to determine the mean photon energy values for the out-of-field photon energy spectrum for a 6 MV photon beam using the GEANT 4-Monte Carlo method. MATERIAL AND METHODS: A specially-designed large water phantom was simulated with a static field at gantry 0°. The source-to-surface distance was 92cm for an open field size of 10×10cm2. The photon energy spectra were calculated at five unique positions (at depths of 0.5, 1.6, 4, 6, 8, and 10cm) along the central beam axis and at six different off-axis distances. RESULTS: Monte Carlo simulations showed that mean radiation energy levels drop rapidly beyond the edge of the 6 MV photon beam field: at a distance of 10cm, the mean energy level is close to 0.3MeV versus 1.5MeV at the central beam axis. In some cases, the energy level actually increased even as the distance from the field edge increased: at a depth of 1.6cm and 15cm off-axis, the mean energy level was 0.205MeV versus 0.252MeV at 20cm off-axis. CONCLUSION: The out-of-field energy spectra and dose distribution data obtained in this study with Monte Carlo methods can be used to calibrate dosimeters to measure out-of-field radiation from 6MV photons.
Authors: Igor Piotrowski; Katarzyna Kulcenty; Wiktoria Suchorska; Marcin Rucinski; Karol Jopek; Marta Kruszyna-Mochalska; Agnieszka Skrobala; Piotr Romanski; Adam Ryczkowski; Dorota Borowicz; Natalia Matuszak; Julian Malicki Journal: Cancers (Basel) Date: 2022-05-30 Impact factor: 6.575
Authors: Marta Kruszyna-Mochalska; Agnieszka Skrobala; Piotr Romanski; Adam Ryczkowski; Wiktoria Suchorska; Katarzyna Kulcenty; Igor Piotrowski; Dorota Borowicz; Kinga Graczyk; Natalia Matuszak; Julian Malicki Journal: Life (Basel) Date: 2022-04-23
Authors: Natalia Matuszak; Marta Kruszyna-Mochalska; Agnieszka Skrobala; Adam Ryczkowski; Piotr Romanski; Igor Piotrowski; Katarzyna Kulcenty; Wiktoria Maria Suchorska; Julian Malicki Journal: Life (Basel) Date: 2022-06-08