Design and manufacturing a CTDI pediatric phantom for CT dosimetry using TLD, ion chambers, and gel dosimetry

Introduction: Nowadays, the demand for CT-scan is increased, and this issue has become a critical subject in radiation protection, because of the risk of cancer especially for children. The quality assurance of CT images is a necessary factor that can effect on children dose. The CT dose index is an important dosimetry index in CT-Scan dosimetry. The purpose of this study is to obtain CTDI in pediatric imaging, using a home-made phantom, and TL dosimetry.   Materials and Methods: A CTDI pediatric phantom was constructed by Lucite material. The phantom consists of 15 cylindrical slabs with diameter of 10 cm, and thickness of 1cm. One central, and four peripheral holes were drilled on each slab. Several rods were designed to be inserted in the holes. The rods were designed so that the CTDI could be measured by ion chambers, gel dosimetry and TLD. To obtain the CTDI, fifty TLD chips were placed in small holes drilled on the rods. The CTDI100 was estimated using the results of TLDs located in central, and peripheral rods. The measurements were repeated using a 10-cm ion chamber. Finally, the CTDI was calculated as: CTDIW=1/3CTDI100, central+2/3CTDI100, pereperal   Results: According to the results of this study, CTDIw values for head imaging, obtained by TLD and ion chamber were 46.42, 50.75 mGy respectively.   Conclusion: The designed phantom can be effectively used in pediatric CT dosimetry. The slab form of the phantom allows us to use radio-chromic dosimeters for CT dosimetry. Further, it can be concluded that the multi-application phantom is useful for use in CT-scan centers.