A lung image reconstruction from computed radiography images as a tool to tuberculosis treatment control.

BACKGROUND: Background: Tuberculosis (TB) is an infectious lung disease with high worldwide incidence that severely compromises the quality of life in affected individuals. Clinical tests are currently employed to monitor pulmonary status and treatment progression. The present study aimed to apply a three-dimensional (3D) reconstruction method based on chest radiography to quantify lung-involvement volume of TB acute-phase patients before and after treatment. In addition, these results were compared with indices from conventional clinical exams to show the coincidence level. METHODS: A 3D lung reconstruction method using patient chest radiography was applied to quantify lung-involvement volume using retrospective examinations of 50 patients who were diagnosed with pulmonary TB and treated with two different drugs schemes. Twenty-five patients were treated with Scheme I (rifampicin, isoniazid, and pyrazinamide), whereas twenty-five patients were treated with Scheme II (rifampicin, isoniazid, pyrazinamide, and ethambutol). Acute-phase reaction: Serum exams included C-reactive protein levels, erythrocyte sedimentation rate, and albumin levels. Pulmonary function was tested posttreatment. RESULTS: We found strong agreement between lung involvement and serum indices pre- and posttreatment. Comparison of the functional severity degree with lung involvement based on 3D image quantification for both treatment schemes found a high correlation. CONCLUSIONS: The present 3D reconstruction method produced a satisfactory agreement with the acute-phase reaction, most notably a higher significance level with the C-reactive protein. We also found a quite reasonable coincidence between the 3D reconstruction method and the degree of functional lung impairment posttreatment. The performance of the quantification method was satisfactory when comparing the two treatment schemes. Thus, the 3D reconstruction quantification method may be useful tools for monitoring TB treatment. The association with serum indices are not only inexpensive and sensitive but also may be incorporated into the assessment of patients during TB treatment.

A lung image reconstruction from computed radiography images as a tool to tuberculosis treatment control

Background: Tuberculosis (TB) is an infectious lung disease with high worldwide incidence that severely compromises the quality of life in affected individuals. Clinical tests are currently employed to monitor pulmonary status and treatment progression. The present study aimed to apply a three-dimensional (3D) reconstruction method based on chest radiography to quantify lung-involvement volume of TB acute-phase patients before and after treatment. In addition, these results were compared with indices from conventional clinical exams to show the coincidence level. Methods: A 3D lung reconstruction method using patient chest radiography was applied to quantify lung-involvement volume using retrospective examinations of 50 patients who were diagnosed with pulmonary TB and treated with two different drugs schemes. Twenty-five patients were treated with Scheme I (rifampicin, isoniazid, and pyrazinamide), whereas twenty-five patients were treated with Scheme II (rifampicin, isoniazid, pyrazinamide, and ethambutol). Acute-phase reaction: Serum exams included C-reactive protein levels, erythrocyte sedimentation rate, and albumin levels. Pulmonary function was tested posttreatment. Results: We found strong agreement between lung involvement and serum indices pre- and posttreatment. Comparison of the functional severity degree with lung involvement based on 3D image quantification for both treatment schemes found a high correlation. Conclusions: The present 3D reconstruction method produced a satisfactory agreement with the acute-phase reaction, most notably a higher significance level with the C-reactive protein. We also found a quite reasonable coincidence between the 3D reconstruction method and the degree of functional lung impairment posttreatment. The performance of the quantification method was satisfactory when comparing the two treatment schemes. Thus, the 3D reconstruction quantification method may be useful tools for monitoring TB treatment. The association with serum indices are not only inexpensive and sensitive but also may be incorporated into the assessment of patients during TB treatment.(AU)

Computed tomography-based volumetric tool for standardized measurement of the maxillary sinus.

Volume measurements of maxillary sinus may be useful to identify diseases affecting paranasal sinuses. However, literature shows a lack of consensus in studies measuring the volume. This may be attributable to different computed tomography data acquisition techniques, segmentation methods, focuses of investigation, among other reasons. Furthermore, methods for volumetrically quantifying the maxillary sinus are commonly manual or semiautomated, which require substantial user expertise and are time-consuming. The purpose of the present study was to develop an automated tool for quantifying the total and air-free volume of the maxillary sinus based on computed tomography images. The quantification tool seeks to standardize maxillary sinus volume measurements, thus allowing better comparisons and determinations of factors that influence maxillary sinus size. The automated tool utilized image processing techniques (watershed, threshold, and morphological operators). The maxillary sinus volume was quantified in 30 patients. To evaluate the accuracy of the automated tool, the results were compared with manual segmentation that was performed by an experienced radiologist using a standard procedure. The mean percent differences between the automated and manual methods were 7.19% ± 5.83% and 6.93% ± 4.29% for total and air-free maxillary sinus volume, respectively. Linear regression and Bland-Altman statistics showed good agreement and low dispersion between both methods. The present automated tool for maxillary sinus volume assessment was rapid, reliable, robust, accurate, and reproducible and may be applied in clinical practice. The tool may be used to standardize measurements of maxillary volume. Such standardization is extremely important for allowing comparisons between studies, providing a better understanding of the role of the maxillary sinus, and determining the factors that influence maxillary sinus size under normal and pathological conditions.

Homogeneous Canine Chest Phantom Construction: A Tool for Image Quality Optimization.

Digital radiographic imaging is increasing in veterinary practice. The use of radiation demands responsibility to maintain high image quality. Low doses are necessary because workers are requested to restrain the animal. Optimizing digital systems is necessary to avoid unnecessary exposure, causing the phenomenon known as dose creep. Homogeneous phantoms are widely used to optimize image quality and dose. We developed an automatic computational methodology to classify and quantify tissues (i.e., lung tissue, adipose tissue, muscle tissue, and bone) in canine chest computed tomography exams. The thickness of each tissue was converted to simulator materials (i.e., Lucite, aluminum, and air). Dogs were separated into groups of 20 animals each according to weight. Mean weights were 6.5 ± 2.0 kg, 15.0 ± 5.0 kg, 32.0 ± 5.5 kg, and 50.0 ± 12.0 kg, for the small, medium, large, and giant groups, respectively. The one-way analysis of variance revealed significant differences in all simulator material thicknesses (p < 0.05) quantified between groups. As a result, four phantoms were constructed for dorsoventral and lateral views. In conclusion, the present methodology allows the development of phantoms of the canine chest and possibly other body regions and/or animals. The proposed phantom is a practical tool that may be employed in future work to optimize veterinary X-ray procedures.

Construction of pediatric homogeneous phantoms for optimization of chest and skull radiographs.

OBJECTIVES: To develop two pediatric patient-equivalent phantoms, the Pediatric Chest Equivalent Patient (PCEP) and the Pediatric Skull Equivalent Patient (PSEP) for children aged 1 to 5 years. We also used both phantoms for image quality evaluations in computed radiography systems to determine Gold Standard (GS) techniques for pediatric patients. METHODS: To determine the simulator materials thickness (Lucite and aluminum), we quantified biological tissues (lung, soft, and bone) using an automatic computational algorithm. To objectively establish image quality levels, two physical quantities were used: effective detective quantum efficiency and contrast-to-noise ratio. These quantities were associated to values obtained for standard patients from previous studies. RESULTS: For chest radiographies, the GS technique applied was 81kVp, associated to 2.0mAs and 83.6µGy of entrance skin dose (ESD), while for skull radiographies, the GS technique was 70kVp, associated to 5mAs and 339µGy of ESD. CONCLUSION: This procedure allowed us to choose optimized techniques for pediatric protocols, thus improving quality of diagnosis for pediatric population and reducing diagnostic costs to our institution. These results could also be easily applied to other services with different equipment technologies.

Wavelet-based algorithm to the evaluation of contrasted hepatocellular carcinoma in CT-images after transarterial chemoembolization.

BACKGROUND: Hepatocellular carcinoma is a primary tumor of the liver and involves different treatment modalities according to the tumor stage. After local therapies, the tumor evaluation is based on the mRECIST criteria, which involves the measurement of the maximum diameter of the viable lesion. This paper describes a computed methodology to measure through the contrasted area of the lesions the maximum diameter of the tumor by a computational algorithm. METHODS: 63 computed tomography (CT) slices from 23 patients were assessed. Non-contrasted liver and HCC typical nodules were evaluated, and a virtual phantom was developed for this purpose. Optimization of the algorithm detection and quantification was made using the virtual phantom. After that, we compared the algorithm findings of maximum diameter of the target lesions against radiologist measures. RESULTS: Computed results of the maximum diameter are in good agreement with the results obtained by radiologist evaluation, indicating that the algorithm was able to detect properly the tumor limits. A comparison of the estimated maximum diameter by radiologist versus the algorithm revealed differences on the order of 0.25 cm for large-sized tumors (diameter > 5 cm), whereas agreement lesser than 1.0 cm was found for small-sized tumors. CONCLUSIONS: Differences between algorithm and radiologist measures were accurate for small-sized tumors with a trend to a small decrease for tumors greater than 5 cm. Therefore, traditional methods for measuring lesion diameter should be complemented non-subjective measurement methods, which would allow a more correct evaluation of the contrast-enhanced areas of HCC according to the mRECIST criteria.

Controle de qualidade e dosimetria em equipamentos de tomografia computadorizada / Quality control and dosimetry in computed tomography units

OBJETIVO: Avaliação de condições dos equipamentos e dosimetria em setores de tomografia computadorizada utilizando protocolos de cabeça, abdome e coluna lombar em pacientes adultos (em três equipamentos distintos) e pediátricos com até um ano e meio de vida (em um dos equipamentos avaliados). MATERIAIS E MÉTODOS: Foram estimados o índice de dose em tomografia computadorizada e a dose média em cortes múltiplos, em exames com pacientes adultos, em três distintos equipamentos. Ainda foram estimadas as doses na superfície de entrada e as doses absorvidas em exame de cabeça para pacientes adultos e pediátricos em um dos equipamentos avaliados. RESULTADOS: Foram realizados testes de controle de qualidade, mecânicos, demonstrando que os equipamentos satisfazem as especificações de uso estabelecidas pelas normas vigentes. Os resultados da dosimetria mostraram que valores de dose média em cortes múltiplos excederam em até 109,0% os valores de níveis de referência, apresentando consideráveis variações entre os equipamentos avaliados neste estudo. As doses absorvidas obtidas com protocolos pediátricos são inferiores aos de pacientes adultos, apresentando redução de até 51,0% na tireoide. CONCLUSÃO: Neste estudo foram avaliadas as condições de operação de três equipamentos tomográficos, estabelecendo quais parâmetros devem ser trabalhados para a implantação de um programa de controle de qualidade nas instituições onde esta pesquisa foi desenvolvida.

OBJECTIVE: Evaluation of equipment conditions and dosimetry in computed tomography services utilizing protocols for head, abdomen, and lumbar spine in adult patients (in three different units) and pediatric patients up to 18 months of age (in one of the units evaluated). MATERIALS AND METHODS: Computed tomography dose index and multiple-scan average dose were estimated in studies of adult patients with three different units. Additionally, entrance surface doses as well as absorbed dose were estimated in head studies for both adult and pediatric patients in a single computed tomography unit. RESULTS: Mechanical quality control tests were performed, demonstrating that computed tomography units comply with the equipment-use specifications established by the current standards. Dosimetry results have demonstrated that the multiple-scan average dose values were in excess of up to 109.0% the reference levels, presenting considerable variation amongst the computed tomography units evaluated in the present study. Absorbed doses obtained with pediatric protocols are lower than those with adult patients, presenting a reduction of up to 51.0% in the thyroid gland. CONCLUSION: The present study has analyzed the operational conditions of three computed tomography units, establishing which parameters should be set for the deployment of a quality control program in the institutions where this study was developed.

Otimização de imagens mamográficas / Optimization of mammographic images

OBJETIVO: Este trabalho tem como objetivo a otimização de imagens mamográficas, com consideráveis reduções de doses. MATERIAIS E MÉTODOS: Neste estudo o feixe de raios-X foi calibrado para cada tensão (kVp), de modo a determinar a melhor combinação de kVp e mAs que irá proporcionar uma densidade ótica (DO) em torno de 1.0 acima da base mais véu do filme utilizado. RESULTADOS: Serão discutidas questões sobre os métodos empregados para a seleção de parâmetros de exposição do feixe de raios-X, seleção da melhor imagem utilizando o método de avaliação gradativa visual, comparações entre as doses e carga do tubo (kVp × mAs) proporcionadas pelas técnicas determinadas neste estudo e pelas utilizadas na rotina clínica do Serviço de Diagnóstico por Imagem do Hospital das Clínicas da Faculdade de Medicina de Botucatu. Neste estudo foram obtidas imagens radiográficas de mama de excelente qualidade, com redução de dose e carga de tubo, respectivamente, de 36,8 por cento e 46,2 por cento, quando comparadas com a técnica utilizada pela rotina clínica da instituição. CONCLUSÃO: Esta pesquisa vem contribuir com a otimização da relação risco-benefício para o paciente e custo-benefício para a instituição.

OBJECTIVE: The aim of this study is the optimization of mammographic images with a considerable radiation dose reduction. MATERIALS AND METHODS: In the present study the X-ray beam was calibrated for each tension (kVp), aiming at determining the best combination between kVp and mAs, resulting in optical densities of about 1.0 above the base-plus-fog density. RESULTS: This study will bring into question the methods for X-ray beam calibration, the choice of the best image by means of visual grading analysis, comparisons between doses and tube load (kVp × mAs) delivered by the techniques described in this study and by those adopted in the clinical routine at Service of Diagnostic Imaging of Faculdade de Medicina de Botucatu Clinics Hospital, Botucatu, SP, Brazil. Excellent breast radiographic images have been obtained with doses and tube loads reduction of respectively 36.8 percent and 46.2 percent in comparison to those employed in our institutions' clinical routine. CONCLUSION: This study is a contribution to the optimization of the risk-benefit ratio for patients and cost-benefit ratio for the institution.