Variations in head tilt during the acquisition of CBCT scans and their effects on effective radiation dose.

OBJECTIVES: This study evaluated the impact of variations in anteroposterior and lateral tilts of patients' head on radiation-weighted doses to organs/tissues and effective doses using three different cone beam computed tomography machines. METHODS: An anthropomorphic phantom was used to estimate radiation doses in three CBCT machines (OP300, Eagle X 3D, and Eagle Edge). Thermoluminescent dosimeters were placed in regions corresponding to pre-stablished organ/tissues. CBCT examinations from the posterior mandible and anterior maxilla regions were acquired, with three different anteroposterior angulations (0°, 30°, and 45°), and from the posterior mandible in three different lateral angulations (0°, 20° to the left, and 20° to the right side). Radiation-weighted doses for each organ/tissue and effective doses were calculated for each machine and angulation. RESULTS: For the posterior mandible acquisitions, anteroposterior angulations of the head at 30° and 45° yielded a reduction in effective doses in all three devices. A 20° tilt to the right side resulted in lower doses than to the left (same side as the FOV). For the anterior maxilla, increased anteroposterior angulation was associated with reduction in effective dose in two devices. CONCLUSION: Effective doses are lower when small FOV CBCT exams of the posterior mandible and anterior maxilla are acquired with increased anteroposterior head angulation at 30° and 45°. For FOV in the posterior mandible, a 20° lateral tilt towards the side opposite to the FOV also yields lower effective doses. The main contribution to these dose reductions is the decrease in dose to salivary glands.

Does dose optimisation in digital panoramic radiography affect diagnostic performance?

OBJECTIVES: To compare the overall diagnostic performance of digital panoramic radiographs obtained with low-dose protocols and to estimate the absorbed dose in the head and neck. MATERIALS AND METHODS: Forty-eight panoramic radiographs were obtained from eight imaging phantoms using six exposure protocols of progressively lower tube voltages (kVp) and currents (mA), as follows: (1) 70 kVp and 12.5 mA, (2) 66 kVp and 10 mA, (3) 66 kVp and 8 mA, (4) 66 kVp and 5 mA, (5) 66 kVp and 4 mA and (6) 66 kVp and 3.2 mA. Five oral radiologists independently evaluated the images and reported all detectable radiographic findings. Intra-examiner reproducibility was assessed by re-evaluation of 25% of the images. The data were analysed using the McNemar and weighted Kappa tests. Absorbed doses of the six protocols were obtained from thermoluminescent dosimeters placed inside a Rando phantom and compared using one-way ANOVA with post hoc Tukey (α = 0.05). RESULTS: The overall diagnostic performance of panoramic radiographs obtained with low-dose protocols did not differ from that of panoramic radiographs obtained with the highest dose (p > 0.05). Moreover, substantial agreement was observed between all protocols. Protocol 1 resulted in the highest absorbed dose and protocols 4, 5 and 6 in the lowest absorbed doses, with the difference being significant (p ≤ 0.05). CONCLUSION: Although digital panoramic radiography is considered a relatively low-dose examination, the radiation dose can be further reduced without negatively affecting its overall diagnostic performance. CLINICAL RELEVANCE: Considering the risks associated with X-rays, digital panoramic radiographs can be obtained at even lower exposure levels.

Assessing pulp stones by cone-beam computed tomography.

OBJECTIVES: The aim of this study was to evaluate the occurrence of pulp stones by cone-beam computed tomography (CBCT) and to correlate their prevalence with patient's gender, location of tooth (right or left of maxillary or mandibular arch), group of teeth, and restorations. MATERIALS AND METHODS: CBCT images of 382 patients randomly selected from the database of the University Oral Radiology Department were retrospectively examined. A total of 2833 tooth images obtained using the i-CAT 3D Imaging System were evaluated. Image analysis was performed with the i-CAT software, and all teeth were evaluated in sagittal, axial, and coronal views. All the measurements were subjected to chi square test, odds ratio, and Fisher's exact tests (p < 0.05). RESULTS: The prevalence of pulp stones was similar between patient's genders and tooth locations. Pulp stones were detected in 31.9% of patients and 9.5% of teeth. Maxillary and mandibular molars were the groups of teeth with the highest frequency of pulp stones. The presence of restorations increased the chance of occurrence of pulp stones by 2.1 times in all teeth examined (p < 0.0001) and by 4.7 times in maxillary teeth (p < 0.0001). CONCLUSIONS: Pulp stones had a high prevalence with molar teeth showing the highest prevalence. The presence of restorations increased the chance of occurrence of these calcifications, specifically in maxillary teeth. CLINICAL RELEVANCE: CBCT provides accurate anatomical details in three dimensions, offering the possibility to view an individual tooth in axial, sagittal, and coronal views. This study performed an investigation of the occurrence of pulp stones by CBCT.

Impact of micro-computed tomography reconstruction protocols on bone microarchitecture analysis.

OBJECTIVE: The aim of this study was to assess the influence of reconstruction protocols of micro-computed tomography (micro-CT) images on analyses of bone microarchitecture. STUDY DESIGN: Micro-CT images of the maxillae of 5 Wistar rats were reconstructed with different protocols by varying the levels of the following tools: smoothing filter (SF; 2-6); ring artifact correction (RAC; 5-15); and beam hardening correction (BHC; 15%-60%). A control protocol (P0; without any correction tool) and a standard protocol (SP; according to the manufacturer's recommendation: SF = 2; RAC = 5; BHC = 45%) were also obtained. For each protocol, 8 bone microarchitecture parameters were calculated (bone volume/total volume [BV/TV], bone surface/total volume [BS/TV], trabecular number [Tb.N], trabecular thickness [Tb.Th], trabecular separation [Tb.Sp], degree of anisotropy [DA], connectivity density [Conn.D], and total porosity [Po-tot]) by using CTAn software. Test protocols were compared with the SP by using 1-way analysis of variance and the Dunnet post hoc test (α = 0.05). RESULTS: An inverse relationship was observed between BHC tool levels and all microarchitecture parameters except BV/TV and Tb.Th. The combination of BHC and SF significantly influenced all microarchitecture parameters except for DA, for which all protocols were similar to the SP (P > .05). CONCLUSIONS: Calculation of bone microarchitecture parameters is influenced by the applied levels of artifact correction tools, mainly BHC and SF. It is necessary to standardize such tool levels for correct data interpretation.

Incidental finding of bullous concha by cone beam computed tomography / Hallazgo incidental de concha bullosa por tomografía computarizada de haz cónico

Abstract This study aimed to describe the imaging aspects of a concha bullosa discovered incidentally by means of cone-beam computed tomography (CBCT) imaging. A female patient underwent a CBCT exam, and a bilateral extensive pneumatization of the middle concha was verified, presenting a larger dimension of the right side and a deviated septum. The patient reported nasal obstruction and loss of smell. The CBCT for covering the maxillofacial region allowed the discovery of this incidental finding, allowing the patient to be referred for appropriate treatment.

Resumen Este estudio tuvo como objetivo describir los aspectos imaginológicos de una concha bullosa hallada incidentalmente por medio de imágenes de tomografía computarizada de haz cónico (TCHC). Una paciente de sexo femenino fue sometida a examen de TCHC y se verificó una neumatización extensa bilateral de la concha media, presentando una mayor dimensión del lado derecho, asi como desvío del tabique. El paciente refirió obstrucción nasal y pérdida del olfato. La TCHC de la región maxilofacial permitió localizar este hallazgo incidental, permitiendo derivar al paciente para el tratamiento adecuado.

Impact of different evaluation methods for diagnostic tasks in panoramic radiography / Impacto de diferentes métodos de evaluación durante el diagnóstico en la radiografía panorámica

Abstract The aim of this study was to evaluate the observers diagnostic performance in panoramic radiography using monitor, tablet, X-ray image view box, and against window daylight as a visualization method in different diagnostic tasks. Thirty panoramic radiography were assessed by three calibrated observers for each visualization method, in standardized light conditions, concerning dental caries, widened periodontal ligament space, and periapical bone defects from the four first molars; mucosal thickening and retention cysts in maxillary sinus; and stylo-hyoid ligament calcification and atheroma. A five-point confidence scale was used. The standard-reference was performed by two experienced observers. Diagnostic values using window light were significantly lower for caries and periapical bone defect and retention cyst, stylo-hyoid ligament calcification detection (p<0.05). For atheroma detection, X-ray image view box, tablet, and widow light had lower accuracy than the evaluation on the monitor (p<0.05). Observers diagnostic performances are worsened using window light as an evaluation method for panoramic radiography for dental, sinus, and calcification disorders, while the monitor was the most reliable method.

Resumen El objetivo de este estudio fue evaluar el desempeño diagnóstico de los observadores en la radiografía panorámica utilizando monitor, tablet, caja de visualización de imágenes de rayos X y contra la luz del día de la ventana como método de visualización en diferentes tareas de diagnóstico. Treinta radiografías panorámicas fueron evaluadas por tres observadores calibrados para cada método de visualización, en condiciones de luz estandarizadas, con respecto a caries dental, espacio del ligamento periodontal ensanchado y defectos óseos periapicales de los cuatro primeros molares; engrosamiento de la mucosa y quistes de retención en el seno maxilar; y calcificación y ateroma del ligamento estilohioideo. Se utilizó una escala de confianza de cinco puntos. La referencia estándar fue realizada por dos observadores experimentados. Los valores diagnósticos con luz de ventana fueron significativamente menores para caries y defecto óseo periapical y quiste de retención, detección de calcificación del ligamento estilohioideo (p <0.05). Para la detección de ateroma, la caja de visualización de imágenes de rayos X, el tablet y la luz de viuda tuvieron una precisión menor que la evaluación en el monitor (p <0.05). El rendimiento diagnóstico del observador empeora al utilizar la luz de la ventana como método de evaluación de la radiografía panorámica para los trastornos dentales, de los senos nasales y de la calcificación, mientras que el monitor fue el método más fiable.