Analysis of intensity variability in multislice and cone beam computed tomography.
ABSTRACT The aim of this study was to evaluate the variability of intensity values in cone beam computed tomography (CBCT) imaging compared with multislice computed tomography Hounsfield units (MSCT HU) in order to assess the reliability of density assessments using CBCT images.
A quality control phantom was scanned with an MSCT scanner and five CBCT scanners. In one CBCT scanner, the phantom was scanned repeatedly in the same and in different positions. Images were analyzed using registration to a mathematical model. MSCT images were used as a reference.
Density profiles of MSCT showed stable HU values, whereas in CBCT imaging the intensity values were variable over the profile. Repositioning of the phantom resulted in large fluctuations in intensity values.
The use of intensity values in CBCT images is not reliable, because the values are influenced by device, imaging parameters and positioning.
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ABSTRACT: Objective With double exposure overlapping cone beam computed tomography scan technique, using cone beam computed tomography (CBCT) acquisition radiation dose, the objective is to obtain apparent density to be similar to the multi-detector CT (MDCT). Methods Factory assurance phantom and water phantom were used for the evaluation of apparent density fidelity of iCAT scans in different modes. Each scan’s apparent density was analyzed for identical regions using image J1.42q freeware. Results The iCAT Classic extended height acquisition with 4-cm central overlap and reconstruction of two groups of 300 projections per rotation for the water and quality-assurance CBCT phantoms resulted in improved apparent density fidelity. This apparent density accuracy was superior to that of iCAT scan at high resolution (600 projections during one rotation). Conclusions Using double exposure, overlapping CBCT scans allow the analyses to be of comparable quality to multi-detector CT.Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, and Endodontology 02/2014; · 1.50 Impact Factor
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ABSTRACT: Purpose: The aim of the paper is to identify, review, analyze, and summarize available evidence in three areas on the use of cross-sectional imaging, specifically maxillofacial cone beam computed tomography (CBCT) in pre- and postoperative dental implant therapy: (1) Available clinical use guidelines, (2) indications and contraindications for use, and (3) assessment of associated radiation dose risk. Materials and Methods: Three focused questions were developed to address the aims. A systematic literature review was performed using a PICO-based search strategy based on MeSH key words specific to each focused question of English-language publications indexed in the MEDLINE database retrospectively from October 31, 2012. These results were supplemented by a hand search and gray literature search. Results: Twelve publications were identified providing guidelines for the use of cross-sectional radiography, particularly CBCT imaging, for the pre- and/or postoperative assessment of potential dental implant sites. The publications discovered by the PICO strategy (43 articles), hand (12), and gray literature searches (1) for the second focus question regarding indications and contraindications for CBCT use in implant dentistry were either cohort or case-controlled studies. For the third question on the assessment of associated radiation dose risk, a total of 22 articles were included. Publication characteristics and themes were summarized in tabular format. Conclusions: The reported indications for CBCT use in implant dentistry vary from preoperative analysis regarding specific anatomic considerations, site development using grafts, and computer-assisted treatment planning to postoperative evaluation focusing on complications due to damage of neurovascular structures. Effective doses for different CBCT devices exhibit a wide range with the lowest dose being almost 100 times less than the highest dose. Significant dose reduction can be achieved by adjusting operating parameters, including exposure factors and reducing the field of view (FOV) to the actual region of interest.The International journal of oral & maxillofacial implants 01/2014; 29 Suppl:55-77. · 1.91 Impact Factor