Commissioning and Assessment of Radiation Field and Dose Inhomogeneity for a Dual X-ray Tube Cabinet Irradiator: To Ensure Accurate Dosimetry in Radiation Biology Experiments

Abstract

PurposeStandardization of X-ray cabinet irradiators dose, geometry, and calibration reporting is an ongoing process. Multi-tube designs have been introduced onto the pre-clinical market and give a theoretical benefit but have not been widely assessed for use in pre-clinical irradiation conditions. The aim of this study was to report on our experience commissioning a dual x-ray source cabinet irradiator (CIXD, Xstrahl Limited, United Kingdom) and assess the dose distribution for various experimental conditions. Materials and MethodsHalf-value layer (HVL) measurement, profile measurements, and output calibration were performed with a calibrated ion chamber. Constancy measurements were performed twice daily over two weeks to assess output fluctuations. Film measurements were completed using solid water to assess percent depth dose and homogeneity within the field and within variable thickness of solid water and phosphate-buffered saline (PBS) solution. Film measurements were repeated for various arrangements of petri dishes filled with PBS or water and in a 3D printed mouse phantom. ResultsThe X-ray tubes measured in-air output was 1.27 Gy/min. The HVL was 1.7 mm Cu. The upper and lower tubes both exhibited the heel effect, but when operated simultaneously the effect was reduced. Ion chamber measurements revealed 15% dose inhomogeneity within the tray area (18 × 18 cm2). Film measurements in the petri dishes indicated minor non-uniformities with the arrangements of experimental apparatus. The mouse phantom with film agreed with ion chamber measurements for various phantom placement and orientations. ConclusionX-ray cell culture irradiation with the dual tube cabinet irradiation is efficient and robust when utilizing established dosimetric tools to confirm output and homogeneity. The conditions assumed for calibrations are often not maintained during experiments. We have confirmed that inhomogeneities are present for single tube use, however they are reduced with simultaneous tube use. Additional dosimetric monitoring should be performed for each unique irradiation setup.