Quantitative Performance Characterization of Radiation Dose for the Carestream CS9600 Cone-Beam Computed Tomography Machine

Abstract

IntroductionCone-beam computed tomography (CBCT) machines produce relatively low levels of harmful ionizing radiation, as compared with the computed tomography devices used in medical practices. The Carestream CS9600 CBCT imaging device has been recently introduced into the marketplace, and the manufacturer reports the use of an increased x-ray tube voltage (120 kVp) for the device, along with a reduced patient dose that is achieved using added filtration. Independent dosimetry studies are performed to ensure appropriate radiation exposure dose levels are within recommended safety guidelines.The purpose of this study is to independently evaluate and measure the radiation exposure dose performance parameters of the CS9600 CBCT, including its multiple field of view, exposure settings, and filtration options. MethodsA thimble ionization chamber and PMMA phantom were used to characterize dose index using the established SEDENTEXTCT evaluation method. ResultsThe phantom-obtained radiation dose index measures ranged from 0.128782–13.848 milligrays (mGy) for the various scanning options evaluated. The field of view, type of filter used, and phantom size all had a direct impact on the relationship between the experimentally obtained dose index measures and the dose area product values reported by the manufacturer. ConclusionsA strong linear correlation was observed between the experimentally obtained dose index measures and the manufacturer-reported dose area product values. The 0.7 mm Cu filter that has been added to the CS9600 reduced the exposure dose index measures even with the x-ray tube kilovoltage peak (kVp) being increased to 120 kVp, as compared with the 0.15 mm Cu filter at 90 kVp.