UBC Theses and Dissertations
Phantom dosimetry of i-CAT CBCT and i-CAT panoramic radiographs in pediatric patients Choi, Ella
Objectives: To obtain head dimensions from patients who received dental CBCT at BC Children’s Hospital (BCCH), to apply this information to design and construct small child and adolescent head phantoms, and to measure and compare the absorbed radiation doses from CBCT and panoramic radiographs using small child, adolescent and adult head phantoms. Materials and Methods: Patients who received dental CBCT at BCCH were surveyed. Head dimensions from each subject’s image were measured to develop adolescent and small child head phantoms. The most commonly used dental CBCT imaging protocols were examined. Absorbed doses were measured for small child, adolescent and adult head phantoms with i-CAT CBCT and Planmeca panoramic radiograph machines. Results: In the patient survey, 32 patients met the inclusion criteria. The most common indications for CBCT referral were for orthodontic treatment, followed by craniofacial abnormality and cleft lip and palate. A small child phantom was developed to represent the child patients with craniofacial abnormality and an adolescent phantom was developed to represent healthy orthodontic patients. Absorbed radiation doses varied depending on machine, imaging protocol, size of phantom and location of the ion chamber in the phantoms. For CBCT images, the highest radiation was measured in the small child phantom while the lowest radiation was measured in the adult phantom. For panoramic radiographs, the i-CAT CBCT panoramic option was compared to the Planmeca panoramic radiograph machine. For both machines, the small child phantom measured the highest while the adult phantom measured the lowest radiation. For the adolescent phantom, lower values were measured with the Planmeca machine while lower values were measured with i-CAT CBCT panoramic option for the small child phantom. Conclusion: Two groups of pediatric patients were referred for dental CBCT at BCCH: young patients with craniofacial abnormality and healthy adolescent patients for orthodontic assessment. A consistent trend was observed for both CBCT and panoramic radiographs: the highest dose was measured in the smallest phantom while the lowest dose was measured in the largest phantom. Radiation in pediatric population is more detrimental than in adult population and it is important to child size the dose and protocol.
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