Detection of in vitro proximal caries in storage phosphor plate radiographs scanned with different resolutions

Objectives: To investigate the effect of the scanning resolution of storage phosphor plate (SPP) radiographs on the detection of proximal caries lesions. Methods: 10 dentists evaluated 72 proximal surfaces of premolars with respect to caries from 15PP radiographs scanned with theoretical spatial resolutions of: (1) the Digora FMX at 7.8 lp mm(-1); (2) the Digora Optime at both 7.8 lp mm(-1) and 12.5 lp mm(-1); and (3) the Durr VistaScan at 10 lp mm(-1) and 20 lp mm(-1), respectively. The lesions were validated by histological examination. Receiver operating characteristic (ROC) analysis was employed. Results: The A(z) value for the radiographs scanned with the Durr VistaScan at 10 lp mm(-1) is significantly lower than those for the other series of radiographs (P = 0.000). Conclusions: For SPP radiographs, an increased theoretical spatial resolution per se is not related to an improved detection of proximal caries.o TEXTO COMPLETO DESTE ARTIGO, ESTARÁ DISPONÍVEL À PARTIR DE AGOSTO DE 2015.37632532

Dose reduction of cone beam CT scanning for the entire oral and maxillofacial regions with thyroid collars

OBJECTIVE: The aim of this study was to evaluate the influence of thyroid collars on radiation dose during cone beam CT (CBCT) scanning. METHODS: Average tissue-absorbed dose for a NewTom 9000 CBCT scanner (Quantitative Radiology, Verona, Italy) was measured using thermoluminescent dosemeter chips in a phantom. The scans were carried out with and without thyroid collars. Effective organ dose and total effective dose were derived using International Commission on Radiological Protection 2007 recommendations. RESULTS: The effective organ doses for the thyroid gland and oesophagus were 31.0 µSv and 2.4 µSv, respectively, during CBCT scanning without a collar around the neck. When the thyroid collars were used loosely around the neck, no effective organ dose reduction was observed. When one thyroid collar was used tightly on the front of the neck, the effective organ dose for the thyroid gland and oesophagus were reduced to 15.9 µSv (48.7% reduction) and 1.4 µSv (41.7% reduction), respectively. Similar organ dose reduction (46.5% and 41.7%) was achieved when CBCT scanning was performed with two collars tightly on the front and back of the neck. However, the differences to the total effective dose were not significant among the scans with and without collars around the neck (p = 0.775). CONCLUSIONS: Thyroid collars can effectively reduce the radiation dose to the thyroid and oesophagus if used appropriately