Development of Computed Tomography Head and Body Phantom for Organ Dosimetry

Introduction: Quality assurance in Computed tomography (CT) centers in developing countries are largely hindered by the unavailability of CT phantoms. The development of a local CT phantom for the measurement of organ radiation absorbed dose is therefore requisite. Material and Methods: Local CT phantoms were designed to meet the standard criteria of 32 cm diameter for body, 16 cm diameter for head, and 14 cm in length respectively. The outer plastic shell was made using poly (methyl methacrylate [PMMA]) sheet. The developed CT phantoms were validated against a standard phantom. Radiation absorbed dose was determined by scanning the setup with the same protocol used for the standard phantom. The local phantoms were then verified for organ radiation absorbed dose measurement using bovine tissues. The set up was CT-scanned, and Hounsfield units (HU) for bovine tissues were obtained. Results: There was no significant difference between the local and standard head phantoms (P=0.060). Similarly, no difference was noted between the local and standard body phantoms (P=0.795). The percentage difference in volume CT dose index (CTDIvol) between the body (local and standard) phantoms was higher than that for the head phantoms. There were no significant differences in HU between bovine and human brain, liver, kidney and lung tissues (P=0.938). Conclusion: The local phantoms showed good agreement with the standard ones. The developed phantoms can be used for CT organ radiation absorbed dose measurement in radiology departments in Nigeria.