Scattered Radiation Distribution Utilizing Three Different Cone Beam Computed Tomography Devices

Abstract

This study aimed to estimate scattered radiation and its spatial distribution around three Cone Beam Computed Tomography (CBCT) devices, in order to determine relatively safe positions for an operator to stand if needed to be inside the CBCT room. The following devices were tested: Morita Accuitomo (CBCT1), Newtom Giano HR (CBCT2), Newtom VGi (CBCT3). Scattered radiation measurements were performed using different kVp, mA and Field of View (FOV) options. An anthropomorphic phantom (NATHANIA) was placed inside the x-ray gantry to simulate clinical conditions. Scattered measurements were taken with the ionization chamber Inovision model 451P Victoreen once placed at fixed distances from each irradiation isocenter, away from the primary beam. A statistically significant (p<0.001) difference was found in the mean value of the scattered radiation estimations between the CBCT devices. Scattered radiation was reduced with a different rate for each CBCT device as distance was increased. For CBCT1 the reduction was 0.047μGy, for the CBCT2 0.036 μGy and 0.079 μGy for CBCT3, for every one meter away from the x-ray gantry. Therefore, at certain distances from the central x-ray, the scattered radiation was below the critical 1mGy. Consequently, an operator could stay inside the room accompanying the patient being scanned, if necessary.