Title of article :
Assessment of skyshine photon dose rates from 9 and 18 MV medical linear accelerators
Author/Authors :
Rostampour, N. Department of Medical Physics - Kermanshah University of Medical Sciences, Kermanshah , Almasi, T. Department of Medical Physics - Kermanshah University of Medical Sciences, Kermanshah , Jafari, S. Department of Radiology - Hamadan University of Medical Sciences, Hamadan , Saeb, M. Department of Radiation Oncology - Seyed-al-Shohada Hospital - Isfahan University of Medical Sciences, Isfahan , Keshtkar, M. Department of Medical Physics and Radiology - Faculty of Medicine - Gonabad University of Medical Sciences, Gonabad , Shokrani, P. Department of Medical Physics - Isfahan University of Medical Sciences, Isfahan
Abstract :
Background: Skyshine describes the radiation scattered by the atmosphere above a LINAC facility to a point on the ground. The aim of this study was to measure the skyshine photon dose rates from two different (9 MV and 18 MV) medical linear accelerators. Materials and Methods: The photon beam was directed upward (180° gantry position), with a maximum photon field size (40 × 40 cm2) at the isocenter. Measurements were obtained around the external points selected outside the room facilities at a horizontal distance from the target by the calibrated RDS-110 survey meter at four points around the isocenter. Results: The measured values of the skyshine photon exposure rates at four points for 9 MV and 18 MV were 0.6, 0.5, 0.5, and 0.4 μSv/h, and 0.6, 0.4, 0.4, and 0.5 μSv/h, respectively. All the measured skyshine photon exposure rates were lower than the values recommended by NCRP 147. Conclusion: There is a poor agreement between the measured and the calculated values; therefore it seems that caution is needed while using the equations available in NCRP 147 or 151.
Keywords :
Skyshine , shielding , radiation measurement , radiation protection , radiotherapy , scattering , medical accelerator
Journal title :
Astroparticle Physics
