Evaluation of radiation dose in multislice spiral CT scan for children embedded teeth / 中华放射医学与防护杂志

Objective To evaluate the radiation dose in both low radiation dose and to conventional radiation dose mode in multislice spiral CT scan for children with embedded teeth,and explore the lowest conditions of exposure in multislice spiral CT scan for children embedded teeth.Methods Eighty cases of children with embedded teeth examined by 16 slices spiral CT were divided into 5 ,25,125 and 250 mAs scanning groups.The scanned pictures of four groups were evaluated by two chief physicians and three associate chief physicians in the radiological department with double blind method.The CTDI_w and DLP in different radiation dose mode were recorded and analyzed with statistics.Results All the four groups scanned pictures in different radiation dose mode could accurately show the structure and the adjacency relation of embedded teeth.Even though the resolution of scanned pictures in S mAs group were inferior to the other three groups on bone trabecula,gingiva and their surrounding soft tissue,it still could meet the requirements of examination.The average DLP in 5 mAs group was only 2% of value in 250 mAs group.Conclusions MSCT in 5 mAs group can not only meet the requirements of examination,but also reduce the radiation dose to patients to the greatest extent.

Normal Representations of Permanent Teeth and Alveolar Bone at Multi-slice Spiral CT / 实用放射学杂志

Objective To explore the spiral the normal representations of permanent teeth and alveolar bone of multi-slice spiral(MSCT). Methods 30 adults with normal teeth were studied by multislice spiral CT scanner,window width and window level was 3000~5000 HU and 1200~1500 HU respectively.MSCT findings were analysed using multiplanar reformation,dental panorama and 3D reconstruction were done in all cases.Results The tooth were showed as multilaryer structures with different density at MSCT because of the mineral content of different part of tooth,from high to low density was enamel,circumpulpal dentin,outside dentin,cementum and pulp.The periodontal membrane was low density located beween the cementum and lamina dura and the thickness was homogeneous.The bone cortex of alveolar bone was successive,the bone trabecula appeared as wirelike or reticulate.Conclusion The structures of permanent teeth and alveolar bone can be displayed clearly by MSCT.Multiplanar reformation,dental panorama and 3D reconstruction are helpful to display the structures of teeth and alveolar bone as well as the relationship around structures.