Development of in-house head CTDI phantoms based on polyester-resin materials

Introduction: CTDI phantoms are used to optimize computed tomography examinations in terms of X-ray image quality and received dose. In this regard, the aim of this study is to develop low price head CTDI phantoms from the polyester-resin (PESR) materials as an alternative phantom.Material and Methods: The PESR was mixed with methyl ethyl ketone peroxide (MEKP) as catalysts. The ratios between catalyst and PESR were 1:150, 1:200, 1:250, and 1:300. The dimensions of the alternative phantoms were designed similar to the standard CTDI phantom, i.e. the length was 15 cm, diameter was 16 cm, and it had 5 holes with a diameter of 1.31 cm. The measured CTDIs using the PESR-MEKP phantoms were compared to those measured using the standard polymethyl methacrylate (PMMA) phantom. The CTDI measurements were carried out using the CT dose profiler and a Philips Brilliance CT 16 slice with a tube voltage and tube loading of 120 kVp and 200 mAs, respectively. Results: The results showed that the values of CTDIs of the PESR-MEKP phantoms are slightly greater (up to 6%) than the standard PMMA phantom. It was found that the CTDI measured using the PESR-MEKP phantom with a ratio of 1:300 has the smallest difference compared to the results of standard PMMA phantom. In addition, in that ratio, the phantom is the most homogeneous.Conclusion: The head CTDI phantoms based on PESR-MEKP have been developed and evaluated. It is found that the PR-MEKP phantom with a ratio of 1:300 has an insignificant difference compared to the standard PMMA phantom. The phantom is constructed easily with more reasonable cost compared to the standard phantom. It might be useful for the CT centers which do not have access to the standard PMMA phantom for dose measurements.