1. Faculty of Technical Physics, Poznan University of Technology, Piotrowo 3, 60-965 Poznan, Poland
2. Institute of Physics, Kazimierz Wielki University, Powstańców Wielkopolskich 2, 85-090 Bydgoszcz, Poland
3. Medical Physics Department, Oncology Center, I. Romanowskiej 2, 85-796 Bydgoszcz, Poland