Optimization of exposure parameters for chest digital radiography in infants and young children / 中华放射医学与防护杂志

Objective To optimize the exposure parameters and reduce the irradiation dose level in infants and young children during digital radiography (DR) chest radiography under the premise of satisfied image quality.Methods The thoracic thickness of 100 patients were measured.Determined the aluminum equivalent of the thoraxes of the infants and young children by comparing the grayscale value and the aluminum step wedge.Another 100 infants and young children of experimental exposure were performed with the aluminum step wedge as a phantom,under AEC control,kV was the only variant to explore the optimal exposure parameters with dose monitor simultaneously.At last,clinical validation was performed.Images quality was compared with x2 test.The radiation dose of two groups was compared with t test.Results The maximum,minimum,average thoracic thickness and their correspondent aluminum equivalent were 13.5 and 2.3 cm,8.0 and 1.4 cm,(10.6 ± 1.3) and 2.0 cm,respectively.The average thoracic thickness of experimental group was (10.1 ± 2.2) cm.The range of entrance surface dose was 0.068-0.056 mGy while the tube voltage range was 55-65 kV.The exposure index range was 0.60-0.74.The visual inspection of aluminum step wedge was from grades 8 to 11 with satisfying image quality at lower radiation.The infant chest X-ray photography exposure parameters formula have been optimized,that was kV =thoracic thickness (cm) × 2 + 38 (constant),mAs (0.8-1.0) with SID =100 cm,without filter grid.Compare to the conventional parameters,the image quality of new method had no significant differences (P ＞ 0.05).The actual average entrance surface dose was (0.048 ± 0.007) mGy,lower than AEC group (0.066 ± 0.008) mGy.The difference was statistically significant (t =16.781,P ＜ 0.001).Conclusions The optimized formula kV =thoracic thickness (cm) ×2 + 38(constant),mAs (0.8-1.0) with SID =100 cm was credible for lowering the radiation exposure with good image quality for clinical diagnosis.

Evaluation of radiopacity and discriminability of various fiber reinforced composite posts / 대한치과보존학회지

The purpose of this study was to compare radiopacity and radiographic discriminability of various FRC-Posts. Six FRC-Posts were investigated ; 1) FRC Postec Plus (Ivoclar Vivadent AG, Schaan, Liechtenstein), 2) Snowlight (Carbotech, Lewis center, OH, USA), 3) Dentin Post (Komet Brasseler, Lamgo, Germany), 4) Rely-X Fiber Post (3M ESPE, St.paul, MN, USA), 5) D.T.-Light Post (BISCO, Schaumburg, IL,USA), 6) Luxapost (DMG, Hamburg, Germany) The radiographs of each post with a reference 1 mm / 2 mm aluminum step-wedge was taken using digital sensor. The optical density were calculated by gray value of 10 x 10 pixel and compared in mm Al equivalent at five points. Six maxillary incisors of similar radiopacity were used. Radiographs of posts in Mx. incisors of lingual side of dry mandible were taken. We showed radiographs and asked the questionnaire to 3 radiologists, 3 endodontists, 3 general practitioners. The questionnaire was comprised of choices of the highest, lowest radiopaque individual post and the choices of best discriminable post at apical, coronal area. The following results were obtained. 1. Each post system showed various radiopacity. 2. There was change of discriminability between each post and simulated specimens regardless of examiner. Although each post showed various radiopacity, the difference of radiopacity did not affect on discriminability.

Estudo radiográfico da densidade óssea, utilizando diferentes penetrômetros de alumínio / A radiographic study of bone density using different aluminum stepwedges

Esta pesquisa objetivou comparar a densidade relativa de fragmentos ósseos mandibulares de suínos com a de penetrômetros de alumínio e comparar a densidade entre dois penetrômetros. Utilizou-se dois penetrômetros de alumínio de diferentes fabricações, denominados de P1 e P2, constituídos por 16 degraus, com 0,3 mm de espessura e 5 fragmentos da cortical vestibular de mandíbulas secas de suínos. Os fragmentos e os penetrômetros foram radiografados com filmes Ultra-speed, tempo de exposição de 0,32 segundos e distância focal de 25 cm. As radiografias foram processadas em uma câmara escura pelo método de tempo e temperatura, e posteriormente digitalizadas. As imagens foram analisadas por meio da ferramenta histograma do programa Image Tool, de acordo com áreas selecionadas nos fragmentos ósseos e nos penetrômetros. A análise dos resultados pelos testes estatísticos ANOVA e Tukey, mostrou que não houve diferenças estatisticamente significantes dos valores da densidade entre os fragmentos ósseos e o degrau 3 (3,6 mmEq/Al) do penetrômetro P1 (p > 0,05). Observou-se que houve diferenças estatisticamente significantes entre os valores da densidade dos fragmentos ósseos e dos degraus 1 (3 mmEq/Al), 2 (3,3 mmEq/Al) e 3 (3,6 mmEq/Al) do penetrômetro P2 (p < 0,05). Finalmente, constatou-se que houve diferenças estatisticamente significantes dos valores da densidade relativa dos degraus 1 (3 mmEq/Al), 2 (3,3 mmEq/Al) e 3 (3,6 mmEq/Al), entre os penetrômetros P1 e P2 (p < 0,05). Concluiu-se que foi possível atribuir valores em milímetros equivalentes de alumínio à densidade relativa dos fragmentos ósseos, e que existe diferença da densidade em pixels entre penetrômetros constituídos pelo mesmo metal, porém com fabricações diferentes, tornando-se necessário a sua padronização quando utilizado como material de referência para estudos de densidade óssea.

This research aimed to compare the relative density of swine?s mandible bone ships with aluminum stepwedge and to compare the density of two different stepwedges. It was used two aluminum stepwedges on different manufacturers, P1 and P2, and 5 fragments from bucal cortical of the dry swine?s mandible. The bone chips and the stepwedges were radiographed using Ultra-speed films, with an exposure time of 0.32s and a focus-film distance of 25 cm. The films were processed manually by the time/temperature method. After that, they were digitalized and analyzed using the histogram tool, from Image Tool software. The data were analyzed by statistics tests of ANOVA and Tukey (5%). The results showed that there was no estatistical differences between the densities of the bone chips and the step number 3 (3,6 mmEq/Al) of the P1 stepwedge (p > 0.05). There were statistical differences between the densities of the bone chips and the steps number 1 (3,0 mmEq/Al), number 2 (3,3 mmEq/Al) and number 3 (3,6 mmEq/Al) of the P2 stepwedge (p < 0.05). Finally, there were statistical differences of densities of the steps number 1, 2 and 3 between both stepwedges (p < 0.05). It was concluded that it is possible to attribute values in aluminum equivalent millimeters to the relative density of bone chips and that there is difference of density in pixels between stepwedges composed with the same metal, although they are from different manufacturers. It is very important to standardize the type of stepwedge when it is used as reference material in bone density studies.