Reliability of Linear and Curvilinear Measurements on Cone-Beam Computed Tomography Images for the Evaluation of Implant Sites and Jaw Pathologies

ABSTRACT Objective: To evaluate the intra-examiner and inter-examiner reliability of linear and curvilinear measurements for the complete assessment of implant sites and jaw pathologies using Cone-Beam Computed Tomography (CBCT). Material and Methods: Fifty cone-beam computed tomographic images of patients were retrieved from the archives of Dentomaxillofacial Radiology. CBCT images taken for implant planning and evaluation of intrabony jaw pathologies (benign cyst/tumor) were included. Two expert oral and maxillofacial radiologists analyzed the images independently and made the measurements. The images for implant planning were analyzed for width, the height of the edentulous site, and the qualitative analysis of bone in the region. Jaw pathologies were assessed for linear dimensions and curvilinear measurements. Results: The inter-observer measurement error for implant site analysis ranged from 0.12 to 0.42 mm with almost perfect agreement (ICC: 0.94 to 1). The inter-observer measurement error for jaw pathology was 0.09 to 0.25 mm (ICC: 0.98-1). Curvilinear measurements showed perfect agreement between the observers. The intraobserver reliability for the various parameters used for the assessment of the implant site and jaw pathologies indicated almost perfect agreement. Conclusion: Reliability between the radiologists is high for various measurements on CBCT images taken for implant planning and jaw pathologies.

Soft Tissue Cephalometric Measurements Among Malaysian Malays and Chinese

Abstract Objective: To obtain the standardized values of individuals of Malaysian Malay and Chinese for further relevant research, such as treatment planning and aesthetical considerations. Material and Methods: In this retrospective study, 440 (305 were Malays and 135 were Chinese) standardized lateral cephalometric radiographs of orthodontic patients selected through simple random sampling are profiled using Holdaway's analysis. The independent t-test was used to assess the disparities in race and gender. The significant level was p<0.05. Results: Significant differences were found between the Malays and Chinese in their skeletal profile convexity, superior sulcus depth, inferior sulcus to the H line and nose prominence. Between Malay females and males, there are significant differences in superior sulcus depth, soft tissue subnasale to H line, basic upper lip thickness, upper lip thickness and nose prominence. Between Chinese males and females, there were differences in their skeletal profile convexity, upper lip to H line, basic upper lip thickness and upper lip thickness. Conclusion: The findings demonstrated the difference between standardized norms and the unique profiles of Malaysian Malays and Chinese. There are significant gender disparities in the soft tissue cephalometric measurements among Malaysian Malay and Chinese subjects.

Computed radiography simulation using the Monte Carlo code MCNPX.

Simulating X-ray images has been of great interest in recent years as it makes possible an analysis of how X-ray images are affected owing to relevant operating parameters. In this paper, a procedure for simulating computed radiographic images using the Monte Carlo code MCNPX is proposed. The sensitivity curve of the BaFBr image plate detector as well as the characteristic noise of a 16-bit computed radiography system were considered during the methodology's development. The results obtained confirm that the proposed procedure for simulating computed radiographic images is satisfactory, as it allows obtaining results comparable with experimental data.

Evolution of X-ray machine quality control acceptance indices.

The quality assurance (QA) of radiographic images based on the operating conditions of X-ray equipment is essential for good image quality, accurate medical diagnostics and for the prevention of health professionals and patients to unnecessary doses of ionizing radiation. This paper presents a historical analysis of 1,635 Quality Assurance Technical Reports of Health Institutions in the state of São Paulo, Brazil, over a seven-year period. Based on acceptable limits for variations between nominal and measured parameters as the variable to determine the quality of X-ray equipment operating conditions, a significant improvement was found in the percentage of acceptance of the overall parameters described in the QA technical reports over this period. As expected, we found a strong concentration in the categories of conventional and portable X-ray equipment, which represent 72% and 84%, respectively, of the total number of equipments. A mechanical parameter such as half-value layer (HVL), which is important not only for image quality but also for radiation protection, showed significant improvements. Again, only 58% of portable X-ray equipment showed HVL values recommended for 80 kVp (above 2.3 mm Al), a percentage that improved to 76% in 2006. With regard to mammographers, which are newer machines, all the analyzed systems presented acceptable HVL values. Conventional X-ray machines showed an increase of this conformity index from 89% in 2000 to 94% in 2006. All this improvement was attributed to the continuous and extensive enforcement of Regulation Act 453 in the state of São Paulo. The improvement in equipment quality control standards is expected to result in the improvement of diagnostic quality, as well as in the reduction of exam repetitions, and thereby reducing the patient's exposure to radiation.

Methodology for the design of a PACS in a small provincial hospital.

This paper describes the design and implantation issues for a Picture Archiving and Communications System (PACS) in a 60-bed provincial hospital. Considerations such as the state of the imaging equipment, preventive maintenance, use and misuse of the equipment and the difficulties regarding migration to an all-digital imaging unit are discussed, as well as the criteria for the selection of the imaging modalities. Finally a design is proposed with four imaging modalities that use open-source database and display workstations. The system is currently under evaluation for possible reproduction in as many as 60 small clinics and hospitals throughout the country.

A computerized system to conduct the Tweed-Merrifield analysis in orthodontics.

Precision in orthodontic diagnosis can increase the chance of therapeutic success. The objective of this study was to describe the development of a computerized system (prototype), created from a printed table of the Cranial Facial Analysis and Total Dentition Space Analysis with Difficulty Index--Tweed-Merrifield Analysis--in order to aid orthodontic diagnosis. The analysis was transposed from the manual format to the digital format. A user-logical and clear interface was sought for the development of the prototype, consisting of tables and graphs, including automatic, fast and accurate calculations. The result was the immediate visualization of the resolution of the analysis after filling out the fields on the computer. This technological innovation can be a helpful instrument for the orthodontist that favors a more accurate dental-cranial-facial analysis, increases patient safety, orients conduct and may contribute to teaching and research.

A computerized system to conduct the Tweed-Merrifield analysis in orthodontics

A precisão no diagnóstico ortodôntico pode aumentar a chance de êxito terapêutico. Este trabalho teve como objetivo descrever o desenvolvimento de um sistema computadorizado (protótipo), criado a partir de uma tabela impressa da Análise Craniofacial e Análise do Espaço Total com o Índice de Dificuldade - Análise de Tweed-Merrifield, que visa auxiliar o diagnóstico ortodôntico. Foi aplicada a transposição da análise do formato manual para o digital. Buscou-se uma interface lógica e simples para o desenvolvimento do protótipo, composta por tabelas e gráficos, incluindo a realização de cálculos automáticos rápidos e precisos. O resultado foi a visualização imediata da resolução da análise, após o preenchimento dos campos no computador. Essa inovação tecnológica pode ser um instrumento de auxílio ao ortodontista, favorecendo a obtenção de um diagnóstico dentocraniofacial mais acurado, aumentando a segurança do paciente, orientando a conduta e pode contribuir para o ensino e a pesquisa.

Direct digital radiography for the detection of periodontal bone lesions.

In this study the diagnostic accuracy of D-speed and E-speed film in the detection of simulated periodontal bone lesions was compared with that of an electronic direct digital image receptor. Lesions of increasing depth were created in 11 human hemimandibles at the buccal cortical plate in the interproximal marginal bone area by means of 1.4 mm diameter round bursa. Specimens were imaged at each lesion stage with the use of all three receptors. Nine viewers used a 5-point rating scale to evaluate whether lesions were present or absent in the resulting images. Receiver operating characteristic curves were generated, and maximum-likelihood curve areas were calculated. The area under the curve was used as the index of diagnostic accuracy. The mean receiver operating characteristic areas for D-speed film, E-speed film, and the direct digital system were 0.745 +/- 0.038, 0.740 +/- 0.038, and 0.741 +/- 0.037, respectively. Critical ratio analysis was used to compare the means. No statistical difference was found between any of the three image receptors (p > 0.05) for the detection of simulated periodontal lesions 1.0 to 3.0 mm in depth, which suggested that the digital system performed comparably with conventional film systems.