ABSTRACT
BACKGROUND AND OBJECTIVE: The research is done in the field of Augmented Reality (AR) for patient positioning in radiation therapy is scarce. We propose an efficient and cost-effective algorithm for tracking the scene and the patient to interactively assist the patient's positioning process by providing visual feedback to the operator. Up to our knowledge, this is the first framework that can be employed for mobile interactive AR to guide patient positioning. METHODS: We propose a pointcloud processing method that, combined with a fiducial marker-mapper algorithm and the generalized ICP algorithm, tracks the patient and the camera precisely and efficiently only using the CPU unit. The 3D reference model and body marker map alignment is calculated employing an efficient body reconstruction algorithm. RESULTS: Our quantitative evaluation shows that the proposed method achieves a translational and rotational error of 4.17 mm/0.82∘ at 9 fps. Furthermore, the qualitative results demonstrate the usefulness of our algorithm in patient positioning on different human subjects. CONCLUSION: Since our algorithm achieves a relatively high frame rate and accuracy employing a regular laptop (without a dedicated GPU), it is a very cost-effective AR-based patient positioning method. It also opens the way for other researchers by introducing a framework that could be improved upon for better mobile interactive AR patient positioning solutions in the future.
Subject(s)
Augmented Reality , Algorithms , Cost-Benefit Analysis , Fiducial Markers , Humans , Patient PositioningABSTRACT
BACKGROUND AND OBJECTIVE: Patient positioning is a crucial step in radiation therapy, for which non-invasive methods have been developed based on surface reconstruction using optical 3D imaging. However, most solutions need expensive specialized hardware and a careful calibration procedure that must be repeated over time.This paper proposes a fast and cheap patient positioning method based on inexpensive consumer level RGB-D sensors. METHODS: The proposed method relies on a 3D reconstruction approach that fuses, in real-time, artificial and natural visual landmarks recorded from a hand-held RGB-D sensor. The video sequence is transformed into a set of keyframes with known poses, that are later refined to obtain a realistic 3D reconstruction of the patient. The use of artificial landmarks allows our method to automatically align the reconstruction to a reference one, without the need of calibrating the system with respect to the linear accelerator coordinate system. RESULTS: The experiments conducted show that our method obtains a median of 1 cm in translational error, and 1∘of rotational error with respect to reference pose. Additionally, the proposed method shows as visual output overlayed poses (from the reference and the current scene) and an error map that can be used to correct the patient's current pose to match the reference pose. CONCLUSIONS: A novel approach to obtain 3D body reconstructions for patient positioning without requiring expensive hardware or dedicated graphic cards is proposed. The method can be used to align in real time the patient's current pose to a preview pose, which is a relevant step in radiation therapy.
Subject(s)
Fiducial Markers , Imaging, Three-Dimensional , Patient Positioning , Photography , Radiotherapy , HumansABSTRACT
Hysteresis is an important technique for edge detection, but the unsupervised determination of its parameters is not an easy problem. In this paper, we propose a method for unsupervised determination of hysteresis thresholds using the advantages and disadvantages of two thresholding methods. The basic idea of our method is to look for the best hysteresis thresholds in a set of candidates. First, the method finds a subset and a overset of the unknown edge points set. Then, it determines the best edge map with the measure chi(2). Compared with a general method to determine the parameters of an edge detector, our method performs well and is less computationally complex. The basic idea of our method can be generalized to other pattern recognition problems.
ABSTRACT
The handled trot of three Lusitano Purebred stallions was analyzed by using 2D and 3D kinematical analysis methods. Using the same capture and analysis system, 2D and 3D data of some linear (stride length, maximal height of the hoof trajectories) and angular (angular range of motion, inclination of bone segments) variables were obtained. A paired Student T-test was performed in order to detect statistically significant differences between data resulting from the two methodologies With respect to the angular variables, there were significant differences in scapula inclination, shoulder angle, cannon inclination and protraction-retraction angle in the forelimb variables, but none of them were statistically different in the hind limb. Differences between the two methods were found in most of the linear variables analyzed.
Subject(s)
Forelimb/physiology , Gait , Hindlimb/physiology , Horses/physiology , Image Processing, Computer-Assisted/methods , Animals , Biomechanical Phenomena , Image Processing, Computer-Assisted/instrumentation , Imaging, Three-Dimensional/instrumentation , Imaging, Three-Dimensional/methods , Male , Range of Motion, Articular , Videotape Recording/instrumentation , Videotape Recording/methodsABSTRACT
OBJECTIVE: To study the gut flora in infants who received fermented milk containing Lactobacillus casei and Streptococcus termophilus and its effect on secretory immunoglobulin levels. MATERIAL AND METHODS: An experimental, randomized, prospective, parallel group study was carried out. Thirty-five infants were included (18 in the treatment group and 17 in the control group) with a mean age of 2 years (SD: 0.6 years; range: 1-3 years). The experimental group received both fermented milk (0.5 l/day) containing L. casei and S. termophilus for 6 weeks and standard cow's milk for the following 6 weeks. The control group received standard cow's milk (0.5 l/day) for 12 weeks. Secretory IgA levels in saliva were evaluated in the experimental group at the start of the study (baseline levels) and 6 weeks later. In both groups, stools were collected to study gut flora at 0, 6 and 12 week. RESULTS: Secretory IgA levels significantly increased (p =0.0063) from a mean baseline value of 2.5 mg/dl to a mean of 3.4 mg/dl at 6 weeks. Gram-negative aerobic flora were decreased in the experimental group after 6 weeks compared with the control group (p =0.0203). The number of infants with Lactobacillus spp in their gut flora was greater in the experimental group than in the control group at week 6 and this difference was statistically significant (p =0.028) at week 12. Conclusion The present study provides evidence of L. casei survival in the gastrointestinal tract and of its effect of increasing secretory IgA.
Subject(s)
Cultured Milk Products/metabolism , Cultured Milk Products/microbiology , Gastroenteritis/metabolism , Gastroenteritis/microbiology , Intestinal Mucosa/metabolism , Intestines/microbiology , Lacticaseibacillus casei/metabolism , Animals , Child, Preschool , Female , Gastroenteritis/immunology , Gram-Negative Bacteria/isolation & purification , Gram-Positive Bacteria/isolation & purification , Humans , Immunoglobulin A, Secretory/immunology , Infant , Intestines/immunology , Male , Milk , Prospective Studies , Saliva/immunology , Streptococcus thermophilus/metabolism , Time FactorsABSTRACT
Objetivo Estudiar las características de la flora microbiana intestinal de niños que recibieron en su dieta leche fermentada con Lactobacillus casei y Streptococcus termophilus y su repercusión en los valores de inmunoglobulinas secretoras. Material y métodos Estudio experimental aleatorizado, prospectivo, con 2 grupos paralelos. Se incluyeron un total de 35 niños (18 en el grupo experimental y 17 en el grupo control), con una edad media de 2 años (DE: 0,6 años; rango: 1-3 años). El grupo experimental recibió en su dieta leche fermentada (500 ml/día) con L. casei y S. termophilus durante 6 semanas y leche de vaca normal estándar durante 6 semanas más. El grupo control recibió leche de vaca normal estándar (500 ml/día) a lo largo de todo el estudio. Se evaluaron los valores de IgA secretora en saliva del grupo experimental al inicio y a las 6 semanas del estudio. Se recogieron heces para el estudio de la flora intestinal a las 0, 6 y 12 semanas en ambos grupos. Resultados Se observó un aumento estadísticamente significativo (p 5 0,0063) de un valor medio basal de 2,5 mg/dl al inicio hasta una media de 3,4 mg/dl a las 6 semanas. Así mismo, se observó un descenso de la flora aeróbica gramnegativa a la semana 6 en comparación con el grupo control (p 5 0,0203). La proporción de niños en los que se les aisló Lactobacillus spp. en la flora intestinal fue superior en el grupo experimental a partir de la semana 6 y llegando a ser estadísticamente significativa (p 5 0,028) a las 12 semanas. Conclusión El presente estudio aporta evidencia sobre la supervivencia de L. casei en el tracto intestinal y su efecto inmunoestimulante en un incremento significativo del la IgA secretora
Objective To study the gut flora in infants who received fermented milk containing Lactobacillus casei and Streptococcus termophilus and its effect on secretory immunoglobulin levels. Material and methods An experimental, randomized, prospective, parallel group study was carried out. Thirty-five infants were included (18 in the treatment group and 17 in the control group) with a mean age of 2 years (SD: 0.6 years; range: 1-3 years). The experimental group received both fermented milk (0.5 l/day) containing L. casei and S. termophilus for 6 weeks and standard cow's milk for the following 6 weeks. The control group received standard cow's milk (0.5 l/day) for 12 weeks. Secretory IgA levels in saliva were evaluated in the experimental group at the start of the study (baseline levels) and 6 weeks later. In both groups, stools were collected to study gut flora at 0, 6 and 12 week. Results Secretory IgA levels significantly increased (p 5 0.0063) from a mean baseline value of 2.5 mg/dl to a mean of 3.4 mg/dl at 6 weeks. Gram-negative aerobic flora were decreased in the experimental group after 6 weeks compared with the control group (p 5 0.0203). The number of infants with Lactobacillus spp in their gut flora was greater in the experimental group than in the control group at week 6 and this difference was statistically significant (p 5 0.028) at week 12. Conclusion The present study provides evidence of L. casei survival in the gastrointestinal tract and of its effect of increasing secretory IgA
Subject(s)
Animals , Infant , Child, Preschool , Humans , Cultured Milk Products/metabolism , Cultured Milk Products/microbiology , Gastroenteritis/metabolism , Gastroenteritis/microbiology , Intestines/immunology , Intestines/metabolism , Intestines/microbiology , Lacticaseibacillus casei/metabolism , Gastroenteritis/immunology , Gram-Positive Bacteria/isolation & purification , Gram-Negative Bacteria/isolation & purification , Immunoglobulin A, Secretory/immunology , Milk , Prospective Studies , Saliva/immunology , Risk FactorsABSTRACT
This technical note describes the development and evaluation of a low-cost motion capture and analysis system (SOMCAM3D). From diverse video sequences obtained by commercial cameras, synchronized by a certain event, and calibrated from a calibration process, the system is able to reconstruct three-dimensional positions in a reference system defined by the calibration process. From these positions, a wide variety of kinematic variables could be calculated. This system aims to analyze movement in applications of gait analysis, sports, animals, ergonomics, robotics, etc. It is designed to work with low-cost equipment (commercial cameras, computers, etc.). Also it allows us to work in 2D, outdoors, and without marks. Finally, this technical note includes a study of how precise and accurate this system is.
Subject(s)
Biomechanical Phenomena , Imaging, Three-Dimensional , Video Recording/instrumentation , Equipment DesignABSTRACT
La presente revisión aborda el metabolismo lipoproteico comparado y la inducción de la aterosclerosis con sus controversias en varios modelos animales pertenecientes a un amplio espectro evolutivo que abarca desde los roedores (ratón, conejo, rata, hámster, cobaya), las aves (paloma), los cetartiodáctilos (cerdo) y los carnívoros (perro) hasta los primates (macacos, Rhesus, mono verde africano) (AU)
Current review presents an overview of the compared lipoprotein metabolism and atherosclerosis development and their controversies in several animal models covering a wide phylogenetic spectrum. Orders are rodents (mice, rabbits, rats, hamsters, guinea pigs), birds (pigeons), cetartiodactyla (pigs), carnivores (dogs) and primates (macaques, Rhesus, African green monkey) (AU)
Subject(s)
Rabbits , Rats , Dogs , Mice , Guinea Pigs , Cricetinae , Animals , Animal Experimentation , Arteriosclerosis/diet therapy , Arteriosclerosis/diagnosis , Arteriosclerosis/metabolism , Lipoproteins/metabolism , Hypercholesterolemia/diet therapy , Hypercholesterolemia/metabolism , Primates/genetics , Primates/metabolism , Birds/metabolism , Cholesterol/analysis , Cholesterol/metabolismABSTRACT
No disponible
No disponible
Subject(s)
Middle Aged , Male , Humans , T-Lymphocytes , Antigens, CD , Diagnosis, Differential , Acquired Immunodeficiency SyndromeABSTRACT
Biliary atresia (BA) is the main source of candidates for paediatric liver transplantation (PLTx) with 64 per 100 of survival. The follow-up of 35 immediate candidates of BA, 19 of them transplanted, induced to the authors to change some details on the BA treatment. This disorder does not finish already with portoenterostomy. Eventually mortality causes are infection and chronic rejection. The functional loss of jejunal segment in the Roux en Y may explain the poor cyclosporin absorption and therefore chronic rejection. By other hand, chronic malnutrition presented by these patients before PLTx may favour infection. Authors recommend more aggressive medical treatment before PLTx and technical improvement in the portoenterostomy with the aim of previous surgery does not difficult posterior PLTx.
