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Showing 3 results for Ct Scan
Determination of obsorbed radiation from dental implant radiography
F. Kaviyani ,
Volume 14, Issue 2 (8-2001)
Abstract
Concern for adverse effects must accompany any use of ionizing radiation. Such concern for the expanded use of CT scanning, conventional tomography and panoramic in dental implant radiology can be expressed by the establishment of absorbed radiation dose for critical tissues (resulting from these radiographic procedures). Potential patient benefit should be weighted against the risk and other disadvantages and/or advantages of a particular radiographic imaging technique. Measurement of dose values can act as a guidline for such risk determinations. The purpose of this study was to measure and compare the absorbed doses of various anatomic sites during these radiographic techniques. The absorbed radiation doses in bone marrow, thyroid gland, salivary gland, eye, brain and skin entrance were determined by placement of lithium fluoride thermoluminescent dosimetres (TLD, S) at selected anatomic sites within and on a humanlike x-ray phantom. The phantom was exposed to radiation from panoramic, linear tomographic and computer- assisted tomographic (CT) stimulated dental implant radiographic examinations. The mean dose was determined for each anatomic site. CT examination showed disruption dose, while panoramic radiography was generally the lowest. The mean absorption value by paratid gland was higher than of other salivary glands.
A comparative study of the diagnostic accuracy on Waters view with CT scan in detecting midface fractures
M. Panjnoush , Gh. Shirani , P. Jozghanbari ,
Volume 19, Issue 3 (6-2006)
Abstract

Background and Aim: In recent years, CT scan has become available as an alternative to conventional radiography. To date, the utility of Waters view in detecting midface fractures has been rarely evaluated. The aim of this study was to compare the diagnostic accuracy and reliability of Waters radiography with CT scan in detecting midface fractures.

Materials and Methods: In this tests evaluation study, waters view and CT scan were performed for 42 patients with midface fracture admitted to maxillofacial surgery department of Shariati hospital. All images were observed and interpreted by an oral and maxillofacial radiologist and an oral and maxillofacial surgeon. Sensitivity, specificity and reliability for Waters view in detecting midface fractures were assessed by Cohen’s kappa test.

Results: Sensitivity and specificity for Waters view in detection of midface fratures by the radiologist were 31.79% and 95.35% and by the surgeon were 29.59% and 93.75% respectively. The highest reliability in CT scan and Waters view (in nasal fractures) by the radiologist was 66.67% and was 58.33% by the surgeon in buttress of zygoma. The highest agreement rate between the radiologist and the surgeon for CT scan was in zygomatic arch (78.95%) and for Waters view was in nasal fracture (62.5%).

Conclusion: Based on the results of this study, the specificity of Waters view is sufficient to diagnose fractures of lateral orbital wall, infraorbital rim, orbital floor, zygomatic arch, frontozygomatic suture, lateral wall of maxillary sinus and Lefort II fracture. The specificity is not sufficient to diagnose fractures of medial orbital wall and anterior, posterior and medial wall of maxillary sinus. Detection of these midface fractures needs other conventional radiographies or CT scan.


Assessment of sphenoid sinus volume in order to determine sexual identity, using multi-slice CT images
Habibeh Farazdaghi, Mohammad Bagher Tavakoli, Shahab Etemadi, Arash Ghodousi,
Volume 29, Issue 3 (10-2016)
Abstract

Background and Aims: Gender determination is an important step in identification. For gender determination, anthropometric evaluation is one of the main forensic evaluations. The aim of this study was the assessment of sphenoid sinus volume in order to determine sexual identity, using multi-slice CT images.

Materials and Methods: For volumetric analysis, axial paranasal sinus CT scan with 3-mm slice thickness was used. For this study, 80 images (40 women and 40 men older than 18 years) were selected. For the assessment of sphenoid sinus volume, Digimizer software was used. The volume of sphenoid sinus was calculated using the following equation: v=∑ (area of each slice × thickness of each slice). Statistical analysis was performed by independent T-test.

Results: The mean volume of sphenoid sinus was significantly greater in male gender (P=0.01).The assessed Cut off point was 9/35 cm3, showing that 63.4% of volume assessments greater than cut off point was supposed to be male and 64.1% of volumetry lesser than cut off point were female.

Conclusion: According to the area under Roc curve (1.65%), sphenoid sinus volume is not an appropriate factor for differentiation of male and female from each other, which means the predictability of cut off point (9/35 cm3 ) is 65/1% close to reality.


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