CBCT Dose Reduction to Lens of Eye Using Leaded Glasses

Objectives: The objective of this study was to measure the shielding effect of leaded glasses, tanning glasses with 1/16” Pb shielding and tanning glasses with lead foil in combination with thyroid collar compared with no shielding equipment to the lens of the eye to evaluate the percentage of dose reduction. Methods: A CIRS female phantom head was used to measure the patient radiation dose to the organs of the head and neck from a Morita X800 CBCT using nano Dot optically stimulated luminescent dosimeters (OSL’S) placed at 23 head and neck sites. Leaded glasses, tanning glasses with 1/16” Pb shielding, tanning glasses with lead foil were placed over the phantoms eyes in conjunction with a thyroid collar. No Protective Equipment was used as a control. Radiation was performed using manufacturers predetermined exposure settings. All dosimeters were exposed three times. Radiation dose fractions to various organ sites were determined using reference values from ICRP-89. Organ equivalent doses were based on ICRP-103 tissue weighting factors. Results: The per cent reduction to the lens of the eye for the leaded glasses compared to no Protective Equipment was 49.2%, 44.6% for the tanning glasses with 1/16” Pb shielding and 38.1% for the tanning glasses with lead foil. For all modes of eye wear the highest organ doses were seen in the salivary glands, extrathoracic airway, and the oral mucosa. The use of proper PPE is necessary to protect the eye from possible cataractogenesis. Conclusions: Research on the correlation between cataract formation and ionizing radiation has shown that the dosage and frequency of exposure play a role in damaging the DNA in the lens of the eye. Here we demonstrate that regular leaded glasses and the tanning glasses with 1/16”Pb shielding are about equal in reducing the dose to the lens of the eye. One caviat, the size of the regular lead glasses might interfere with anatomical landmarks while tanning glasses would allow more diagnostic information. Further studies should be performed.

Does the addition of a lead foil to digital radiographic receptors influence image contrast and approximal caries lesions diagnosis?

Objectives: To access the influence of the addition of a lead foil to intraoral digital radiographic receptors on image contrast and approximal caries lesions diagnosis. Methods: 40 posterior teeth were distributed in silicone phantoms composed of two premolars, two molars and a non-test canine. Radiographic images of the phantoms were obtained with and without the incorporation of a lead foil, using the Digora Optime and Digora Toto systems. Four observers scored the images for the presence of caries lesions, using a 5-point scale. Images of an aluminum step wedge were acquired with and without the incorporation of a lead foil. Gray values and standard deviation of gray values were calculated in different thickness of the step wedge and, then, contrast variation was calculated. Results: Presence of a lead foil did not influence caries lesions diagnostic values, regardless of the type of digital system (p > 0.05). In general, the objective analysis was not influenced by the presence of a lead foil in any of the tested systems (p > 0.05). However, Digora Toto images showed greater gray values, lower standard deviation of gray values and lower contrast variation, regardless of the presence of the lead foil (p < 0.05). Conclusions: The addition of a lead foil to intraoral digital receptors did not influence image contrast nor caries lesions diagnosis.

Influence of the incorporation of a lead foil to intraoral digital receptors on the image quality and root fracture diagnosis

Objective: To evaluate the quality of images obtained with the addition of a lead foil to intraoral digital receptors. Methods: Radiographic images of 34 single-rooted human teeth - 19 with vertical root fracture (VRF) and 15 of the control group - were obtained with and without the addition of a lead foil, using the VistaScan, Express, Digora Optime and Digora Toto systems. Images were evaluated by five observers regarding the diagnosis of VRF, using a 5-point scale. In a second moment, an observer preference analysis related to the presence of the lead foil was performed. Images of an acrylic phantom were also obtained with and without the addition of a lead foil, and the quantities of uniformity, grey value and standard deviation of grey values were obtained. Results: There were no significant differences in the VRF diagnostic values, considering the presence of the lead foil. Regarding the image quality preference, the observers preferred images acquired with the lead foil for all systems tested, but with greater values for Digora Optime (61.33%) and Express (61.33%). The presence of the lead foil did influence the image uniformity in all systems tested ( p < 0.05). Moreover, the lead foil increased the mean of grey values for Digora Optime and Express images ( p < 0.05), however it did not influence the SD in any of the digital systems ( p > 0.05). Conclusion: The addition of a lead foil to intraoral digital receptors produces a positive effect in the image quality objectively detected by means of uniformity and subjective visual preference.

Reliable Ala-Tragus Line for the Orientation of Occlusal Plane by Cephalometry

Introduction: The aim of the study was to determine the most reliable ala-tragus line for the orientation of the occlusal plane in edentulous patients during complete denture fabrication by cephalometry. Materials and Methods: Lateral cephalometric radiographs of 37 dentate subjects were taken at maximum intercuspation. Steel balls were used as radio opaque markers which were adhered to superior border, middle point, and inferior border of tragus as well as the inferior border of ala of nose. Lead foil was cemented to cover the mesio-palatal cusp of maxillary first molar. Tracings of cephalogram were done. Angle between ala-tragus superior, ala-tragus middle and ala-tragus inferior in relation to occlusal plane were measured. Variables were determined and data were analyzed using SPSS version 17 (SPSS, Inc. Chicago, III). Results: The angle formed between occlusal plane and ala tragus middle had lowest mean value of 2.39°. The highest was measured with ala tragus superior 5.18°, while the angle formed with ala tragus inferior was 3.60°. The differences between the three planes in relation to the occlusal plane were significantly different in total subjects as well as in both males and females (p < 0.001). Conclusion: Statistical analysis showed that the middle point of the tragus with the inferior border of the ala of the nose was most accurate in orienting the occlusal plane.