RESUMO
In many countries, computed radiography (CR) systems represent the majority of equipment used in digital mammography. This study presents a method for optimizing image quality and dose in CR mammography of patients with breast thicknesses between 45 and 75 mm. Initially, clinical images of 67 patients (group 1) were analyzed by three experienced radiologists, reporting about anatomical structures, noise and contrast in low and high pixel value areas, and image sharpness and contrast. Exposure parameters (kV, mAs and target/filter combination) used in the examinations of these patients were reproduced to determine the contrast-to-noise ratio (CNR) and mean glandular dose (MGD). The parameters were also used to radiograph a CDMAM (version 3.4) phantom (Artinis Medical Systems, The Netherlands) for image threshold contrast evaluation. After that, different breast thicknesses were simulated with polymethylmethacrylate layers and various sets of exposure parameters were used in order to determine optimal radiographic parameters. For each simulated breast thickness, optimal beam quality was defined as giving a target CNR to reach the threshold contrast of CDMAM images for acceptable MGD. These results were used for adjustments in the automatic exposure control (AEC) by the maintenance team. Using optimized exposure parameters, clinical images of 63 patients (group 2) were evaluated as described above. Threshold contrast, CNR and MGD for such exposure parameters were also determined. Results showed that the proposed optimization method was effective for all breast thicknesses studied in phantoms. The best result was found for breasts of 75 mm. While in group 1 there was no detection of the 0.1 mm critical diameter detail with threshold contrast below 23%, after the optimization, detection occurred in 47.6% of the images. There was also an average MGD reduction of 7.5%. The clinical image quality criteria were attended in 91.7% for all breast thicknesses evaluated in both patient groups. Finally, this study also concluded that the use of the AEC of the x-ray unit based on the constant dose to the detector may bring some difficulties to CR systems to operate under optimal conditions. More studies must be performed, so that the compatibility between systems and optimization methodologies can be evaluated, as well as this optimization method. Most methods are developed for phantoms, so comparative studies including clinical images must be developed.
Assuntos
Neoplasias da Mama/diagnóstico por imagem , Meios de Contraste/química , Mamografia/métodos , Doses de Radiação , Mama/patologia , Neoplasias da Mama/diagnóstico , Simulação por Computador , Feminino , Humanos , Processamento de Imagem Assistida por Computador , Imagens de Fantasmas , Intensificação de Imagem Radiográfica/instrumentação , Intensificação de Imagem Radiográfica/métodos , Radiometria/métodos , Reprodutibilidade dos TestesRESUMO
This work proposes to detect possible affections or abnormalities in pelvic belt region in a group of rhythmic gymnastics due to the need for studies in the field of biomechanics and structural evaluation of human being. The methodology for this study used a tool called Biophotogrammetry. This technique has analyzed, through scanned images, the structural pelvic girdle bone profile of 64 practitioners of rhythmic gymnastics. The results of this study have presented weighted averages of 45.07±9.78° between the right pelvic slope (RPS) and left pelvic slope (LPS) and 91.74±2.50° for flattening of the pelvis (FP). Therefore, it is concluded that the Biophotogrammetry technique provides data related to the gold standard radiography test, used as reference for the pelvic girdle measurements.
Assuntos
Ginástica/fisiologia , Ossos Pélvicos/anatomia & histologia , Ossos Pélvicos/fisiologia , Fotogrametria/métodos , Fenômenos Biomecânicos , Criança , Pré-Escolar , HumanosRESUMO
The objective of this study was to compare and correlate the Portable Ultra Sound (US) measuring technique to the skinfold measuring technique (SF) to estimate body fat percentage (%F) in young adults. Sixty military were evaluated, all males, divided in two groups: Group 1 (normal) composed by 30 military with Body Mass Index (BMI) until 24.99 kg/m(2) and Group 2 (overweight) composed by 30 military with BMI > 25 kg/m(2). Weight, height, skinfolds and ultrasound were measured in 9 points (triceps, subscapular, biceps, chest, medium axillary, abdominal, suprailiac, thigh and calf). Body fat average values obtained by skinfold thickness and ultrasound measurements were 13.25 ± 6.32 % and 12.73 ± 5.95 % respectively. Despite significant differences in measurements of each anatomical site, it was possible to verify that the total final body fat percentage calculated by both techniques did not present significant differences and that overweight group presented greater similarity between the values obtained using caliper and ultrasound equipment.
Assuntos
Tecido Adiposo/fisiologia , Dobras Cutâneas , Ultrassom/instrumentação , Ultrassom/métodos , Antropometria , Índice de Massa Corporal , Humanos , Masculino , Padrões de Referência , Adulto JovemRESUMO
This study aimed to test a protocol of measurements based on Biophotogrammetry to Analysis of Respiratory Mechanics (BARM) in healthy children. Seventeen normal spirometric children (six male and 11 female) were tested. Their performed maneuvers of forced inspiratory vital capacity were recorded in the supine position. The images were acquired by a digital camera, laterally placed to the trunk. Surface markers allowed that the files, exported to CorelDraw® software, were processed by irregular trapezoids paths. Compartments were defined in the thoracic (TX), abdominal (AB) and the chest wall (CW). They were defined at the end of an inspiration and expiration, both maximum, controlled by a digital spirometer. The result showed that the measured areas at the inspiratory and expiratory periods were statistically different (p<0.05). It reflects the mobility of CW and compartments. In conclusion, the proposed method can identify the breathing pattern of the measured subject using images in two dimensions (2D).
Assuntos
Interpretação de Imagem Assistida por Computador/métodos , Modelos Biológicos , Fotogrametria/métodos , Mecânica Respiratória/fisiologia , Parede Torácica/anatomia & histologia , Parede Torácica/fisiologia , Criança , Pré-Escolar , Simulação por Computador , Feminino , Humanos , MasculinoRESUMO
The present study aimed to compare the estimates of body liquid volumes performed by two bioimpedance spectrometry techniques. One based on a step response technique (BIS-PEB) and second one based on multifrequency Xitron Hydra 4200 equipment (Xitron Technologies, San Diego, CA, USA). The convenience sample was initially composed of 422 students from a military parachuting course of the Brazilian Army. From such sample 42 male students were randomly selected to be evaluated during three weeks. The anthropometrical characteristics of the sample can be summarized as: 25.18 +/- 4.10 years old; weight equals of 76.77 +/- 7.84 kg; height equals to 174.96 +/- 5.67 cm; body mass index (BMI) equal to 25.05 +/- 2.11 kg m(-2). Bland-Altman graphics were used to compare the two methods in what concerns to estimate of extracellular fluid (ECF), intracellular fluid (ICF), and total body water (TBW). One can observe that the estimates of the two techniques present a good correlation, especially in the case of ECF (r = 0.975). The present study indicates that BIS-PEB technique associated with De Lorenzo equation can supply noninvasive estimates of body fluid volumes comparable to Xitron Hydra 4200 equipment.
Assuntos
Líquidos Corporais , Pletismografia de Impedância/métodos , Humanos , Masculino , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Adulto JovemRESUMO
The aim of the present study was to derive an objective and noninvasive assessment of osteoarthritis of the knee joint by bioimpedance spectrocopy (BIS). The study was performed in Brazilian Military Parachuters and intends to contribute to the improvement of the early diagnosis of joint degeneration. Twelve male volunteers (24 knee joints) participated in the study. A novel index (ID) to assess the disease was proposed from the raw bioimpedance parameter. This index was compared with a subjective rating (Dejour scale) performed by 3 therapists. The results indicated that the values of ID were significantly different (p0.001) between the control group (class 1 of Dejour) and the pathological group (class 2 or higher). A Spearman correlation of -0.81 between the values of ID and the therapists rating was detected. Despite the need of increasing the sample size, the novel technique seems to be capable of supplying an objective and non-invasive tool for helping the diagnosis of the knee osteoarthritis.