Biomedical subjects

G Ferrigno

Publications and source records attributed to G Ferrigno.

At least 37 records · Page 2Linked to original sources

PubMed2001

Optimisation of shape kernel and threshold in image-processing motion analysers.

The aim of the work is to optimise the image processing of a motion analyser. This is to improve accuracy, which is crucial for neurophysiological and rehabilitation applications. A new motion analyser, ELITE-S2, for installation on the International Space Station is described, with the focus on image processing. Important improvements are expected in the hardware of ELITE-S2 compared with ELITE and previous versions (ELITE-S and Kinelite). The core algorithm for marker recognition was based on the current ELITE version, using the cross-correlation technique. This technique was based on the matching of the expected marker shape, the so-called kernel, with image features. Optimisation of the kernel parameters was achieved using a genetic algorithm, taking into account noise rejection and accuracy. Optimisation was achieved by performing tests on six highly precise grids (with marker diameters ranging from 1.5 to 4 mm), representing all allowed marker image sizes, and on a noise image. The results of comparing the optimised kernels and the current ELITE version showed a great improvement in marker recognition accuracy, while noise rejection characteristics were preserved. An average increase in marker co-ordinate accuracy of +22% was achieved, corresponding to a mean accuracy of 0.11 pixel in comparison with 0.14 pixel, measured over all grids. An improvement of +37%, corresponding to an improvement from 0.22 pixel to 0.14 pixel, was observed over the grid with the biggest markers.

Algorithms↗

PubMed2001

Voluntary head stabilisation in space during oscillatory trunk movements in the frontal plane performed before, during and after a prolonged period of weightlessness.

The ability to voluntarily stabilise the head in space exhibited by two subjects during lateral rhythmic oscillations of the trunk has been investigated before, during and after a prolonged period of microgravity (microG) exposure. In flight acquisitions were performed onboard the Core Module of the Russian Space Station MIR as part of the T4 "Human Posture in Microgravity" experiment of the 179-days ESA-RKA mission EUROMIR-95. Data collection and kinematic analysis were performed by means of a space-qualified version of the automatic motion analyser ELITE. Head stabilisation in space strategy was estimated by means of the head anchoring index and cross-correlation analysis. Results show that head orientation may be well stabilised about the roll axis both with and without the presence of visual information. This was true despite the expected reduction in vestibular efficiency and muscular proprioception occurring in-flight. In one subject, however, vision was found to improve head stabilisation in space post-flight, presumably to recover from the postural deficiency induced by the long-term microG exposure. Head stability during trunk movements was achieved with either over-compensatory (out-of-phase), under-compensatory (in-phase) or mixed movement strategies, as was attested by the analysis of cross-correlation functions between head and shoulder movements. In weightlessness, vision occlusion seemed to influence the choice of the strategies to be used as well as the reduction of movement variability. The feedforward nature of compensatory head movements suggests that head stabilisation could be based in weightlessness on the internal postural body scheme, supposed to be adapted to the weightless environment within 5 months of microG exposure.

Adaptation, Biological↗

PubMed2001

Static and dynamic postural control in long-term microgravity: evidence of a dual adaptation.

The adaptation of dynamic movement-posture coordination during forward trunk bending was investigated in long-term weightlessness. Three-dimensional movement analysis was carried out in two astronauts during a 4-mo microgravity exposure. The principal component analysis was applied to joint-angle kinematics for the assessment of angular synergies. The anteroposterior center of mass (CM) displacement accompanying trunk flexion was also quantified. The results reveal that subjects kept typically terrestrial strategies of movement-posture coordination. The temporary disruption of joint-angular synergies observed at subjects' first in-flight session was promptly recovered when repetitive sessions in flight were analyzed. The CM anteroposterior shift was consistently <3-4 cm, suggesting that subjects could dynamically control the CM position throughout the whole flight. This is in contrast to the observed profound microgravity-induced disruption of the quasi-static body orientation and initial CM positioning. Although this study was based on only two subjects, evidence is provided that static and dynamic postural control might be under two separate mechanisms, adapting with their specific time course to the constraints of microgravity.

Adaptation, Physiological↗

PubMed2001

GFP-centrin as a marker for centriole dynamics in the human breast cancer cell line MCF-7.

Centrosome duplication plays an important role in genomic stability through bipolar spindle formation and equal chromosome segregation during mitosis. Defects in centrosome duplication and centrosome amplification correlate with aggressive tumors and aneuploidy. Cyclin-dependent cell cycle regulators play a key role in signaling centrosome duplication and the tumor suppressor genes p53, BRCA1 and BRCA2 are suspected to function at mitotic checkpoints that monitor centrosome duplication. The relationship between loss of hormone dependence in breast cancer, and signaling of centrosome duplication in tumor progression is not known. We have developed a MCF-7 cell line expressing GFP-centrin that allows direct visualization of centriole duplication during the cell cycle in living cells. GFP-centrin is expressed and selectively incorporated into the structure of both centrioles making them clearly visible in living cells. Our studies demonstrate three important aspects of recombinant GFP-centrin incorporation into centrioles. 1) GFP-centrin transfected cells grow normally in culture and show no adverse effect associated with GFP-centrin expression; 2) newly duplicated centrioles incorporate centrin during their genesis; and 3) GFP-centrin incorporation into centrioles does not grossly affect cell cycle progression, or centrosome function.

Aneuploidy↗

PubMed2000

Real-time opto-electronic verification of patient position in breast cancer radiotherapy.

OBJECTIVE: The clinical application of an opto-electronic system for real-time three-dimensional (3D) control of patient position in breast cancer radiotherapy is described. The specific features of the motion analysis technology (shape recognition of passive markers) are detailed, and the outcomes of its clinical use for quantitative position control and immobility verification of the thoracic irradiation field during breast cancer treatment are reported. MATERIALS AND METHODS: The position control system is based on the ELITEtrade mark opto-electronic motion analyzer, which provides in real time the 3D coordinates of a set of passive markers (plastic hemispheres 3 mm in diameter) previously placed on selected landmarks on the patient's skin. The system-dedicated hardware performs marker recognition by means of 2D correlation of shape with a predefined marker modeling mask. This feature ensures a high accuracy, even with small marker dimensions, and successful analysis in a noisy environment (due to room light, reflexes, etc.). The patient repositioning control was based on a comparison between the current positions of the markers and a corresponding reference configuration. The resulting marker displacements were graphically displayed in real time for immediate control. This information was not provided to the operator as a repositioning tool. Instead, the kinematic data was stored for subsequent off-line analysis aimed at quantifying the different factors contributing to patient mis-positioning (initial repositioning errors, patient's breathing, and random movements) when conventional means for patient alignment (laser centering) and immobilization (casting techniques) are used. RESULTS: Clinical application of the system revealed median 3D localization errors for the directly controlled anatomical landmarks of around 4.5 mm. This value is proposed to represent the intrinsic accuracy of conventional laser-centering techniques in breast cancer radiotherapy, including the effects of patient body deformations. When the positional inaccuracies introduced by patients' respiration were also considered, the extent of the resulting 3D mis-positioning of the control points increased to median values of up to 8 mm. CONCLUSIONS: The reported clinical trial confirms the significant role that real-time opto-electronic motion analysis based on passive markers can have in augmenting the accuracy of patient repositioning and immobility verification in the radiotherapy of a non-rigid body area while also accounting for physiological movements. Evaluation of the data collected during each irradiation session for five patients provided valuable information concerning the optimization of the efficacy of traditional methods for patient centering and immobilization.

Breast Neoplasms↗

PubMed2000

Real-time three-dimensional motion analysis for patient positioning verification.

BACKGROUND AND PURPOSE: This paper describes the technology and methods involved in a system for automatically checking the position of patients at radiotherapy units. This is proposed for improving the accuracy in the irradiation geometrical set-up, which is a crucial factor in radiotherapy quality control. MATERIALS AND METHODS: The system is based on real-time opto-electronics and close-range photogrammetry and detects multiple passive markers placed on selected patient skin landmarks. Patient alignment and position monitoring is carried out by comparing the current three-dimensional positions of the markers with those of an initial reference position acquired during the simulation procedure and/or the first irradiation session. The system was used to measure the accuracy of conventional laser centering techniques for patient repositioning. Inaccuracies due to breathing and random movements were also taken into account. Professional technicians were asked to reposition three volunteer subjects carefully using a traditional laser centering procedure. RESULTS: The results revealed significant repositioning errors even in highly controlled conditions, affecting particularly body areas relatively far from the skin reference points used for laser alignment. CONCLUSIONS: The outcome of the experimental application of this technology confirms its potential as a tool for patient repositioning and automatic detection of any errors caused by breathing or other unpredictable movements. The real-time feedback on the patient's position given by the system provides operators with appropriate visual indices and allows them to take suitable countermeasures in case of significant failures. In addition, the use of the system output for automatic position control is envisaged.

Artifacts↗

PubMed2000

Quantitative analysis of neutral body posture in prolonged microgravity.

The experiment was performed during a 6-month space flight and focused on the quantitative three-dimensional description of the Neutral Body Posture (NBP) and of subjects' spine anthropometry in Erect Posture (EP). The NBP joint angles' configuration is described along the long-term microgravity exposure and compared with respect to previous in-flight collected data. Observed spinal length modification during EP in-flight is related to on-ground investigations focused on circadian anthropometrical fluctuations. The flattening of the spinal lumbar lordosis and thoracic kyphosis is also described. Even though only two subjects were studied, this analysis points out the maturity of the opto-electronic technology for the quantitative analysis of posture in microgravity and confirms the need of enriching the anthropometrical database of human postures in weightlessness for the design optimization of permanently inhabited space modules.

Adult↗

PubMed2000

Perspectives on MEMS in bioengineering: a novel capacitive position microsensor.

We describe a novel capacitive position sensor using micromachining to achieve high sensitivity and large range of motion. These sensors require a new theoretical framework to describe and optimize their performance. Employing a complete description of the electrical fields, the sensor should deviate from the standard geometries used for capacitive sensors. By this optimization, the sensor gains a twofold increase in sensitivity. Results on a PC board 10x model imply that the micromachined sensor should achieve a sensitivity of less than 10 nm over 500-micron range of travel. Some bioengineering applications are addressed, including positioning of micromirrors for laser surgery and dose control for implantable drug delivery systems.

Drug Delivery Systems↗

PubMed1999

Long-term adaptation of postural control in microgravity.

Orbital microgravity represents a unique environment, which allows the isolation of variables assumed to be involved in the mechanism of body positioning in space. In this context, the alignment of the trunk axis along allocentric references and the positioning of the body center of mass inside the supporting base compete for the role of the primary-controlled variable when assuming erect posture. This paper reports the quantitative evaluation of the postural strategies exhibited by two subjects with feet fixed to the floor of the space module along a 4-month period of exposure to microgravity. With respect to previous findings in parabolic flights and short term space missions, the analysis focused on long-term process of sensorimotor adaptation to weightlessness. Results show that while trunk-axis orientation is preserved and used as a stable postural frame of reference, the positioning of the body center of mass appears to be significantly biased backward and turns out to be involved in a long-term process of adaptation throughout the entire flight towards the re-emergence of a typically terrestrial postural regulation compatible with equilibrium.

Adult↗

PubMed1999

Methodological and technological implications of quantitative human movement analysis in long term space flights.

In the frame of the 179-days EUROMIR '95 space mission, two in-flight experiments foresaw the analysis of three-dimensional human movements in microgravity. For this aim, a space qualified opto-electronic motion analyser based on passive markers was installed onboard the MIR Space Station. The paper describes the experimental procedures designed in order to face technical and operational limitations imposed by the critical environment of the orbital module. The reliability of the performed analysis is discussed, focusing two related aspects: accuracy in three-dimensional marker localisation and data comparability among different experimental sessions. The effect of the critical experimental set-up and of TV cameras optical distortions is evaluated on in-flight acquired data, by performing an analysis on Euclidean distance conservation on rigid bodies. An optimisation method for the recovering of a unique reference frame throughout the whole mission is described. Results highlight the potentiality that opto-electronics and close-range photogrammetry have for automatic motion analysis onboard orbital modules. The discussion of the obtained results provides general suggestions for the implementation of experimental human movement analysis in critical environments, based on the suitable trade-off between external constraints and achievable analysis reliability.

Algorithms↗

PubMed1998

Implementation and application of real-time motion analysis based on passive markers.

A method for real-time motion analysis based on passive markers is presented. An opto-electronic automatic motion analyser was used as hardware platform and the real-time operation was based on the interfacing between two levels of the system architecture. True real-time acquisition, processing and representation of two-dimensional and three-dimensional kinematics data were implemented through a newly conceived data acquisition procedure and high speed optimisation of the kinematics data processing. The method allows one to operate the motion analysis system in real-time; even when the data elaboration unit is required to perform other processing functions, the only consequence is a decrease in system sampling rate. The maximum number of processed and plotted markers in three dimensions at the highest system sampling rate (100 Hz) turned out to be suitable for the implementation of analytical and visual kinematics biofeedback. An example of the achievable level of complexity in terms of marker disposition model and graphic representation is reported by describing a demonstration of the real-time representation of human face movements. A clinical application of the method for patient position definition and control at radiotherapy units is presented.

Biomechanical Phenomena↗

PubMed1998

Principal component analysis of chest wall movement in selected pathologies.

A method is presented for assessing a compact set of parameters characteristic of respiratory system functional status. 3D movements of points in the chest wall and the volumes of chest wall compartments (pulmonary rib cage, abdominal rib cage and abdomen) are considered. The co-ordinates of these points are measured using an opto-electronic system for 3D motion analysis. Principal component analysis is applied to these data. The behaviour of the eigenvectors of the covariance matrix of the 3D co-ordinates of the points on the chest wall shows close agreement with the pathology characteristics. The same is found for the percentage of total variance explained by the principal components of the volume variations. In this case, the higher values of variance percentage explained indicate independent motions (active or passive) in the degrees of freedom of the system identified by partitioning the total volume into compartments.

Adult↗

PubMed1997

Automatic integrated analysis of jaw and lip movement in speech production.

A noninvasive methodology for studying the kinematics of speech production is presented. It is based on the tracking of very small and light passive markers attached to the subjects' face. Using a pair of TV cameras, the 3-D markers' positions are computed in real time, at a subpixel accuracy, by a dedicated hardware. From these data, the time course of a set of parameters which describe lip and jaw movement is computed; in addition, a semiautomatic procedure that identifies the exact onset and offset of the investigated sequences has been developed. To compare the results over different productions, a time normalization procedure based on a continuous inverse Fourier transform has been implemented.

Humans↗

PubMed1997

Human respiratory muscle actions and control during exercise.

We measured pressures and power of diaphragm, rib cage, and abdominal muscles during quiet breathing (QB) and exercise at 0, 30, 50, and 70% maximum workload (Wmax) in five men. By three-dimensional tracking of 86 chest wall markers, we calculated the volumes of lung- and diaphragm-apposed rib cage compartments (Vrc,p and Vrc,a, respectively) and the abdomen (Vab). End-inspiratory lung volume increased with percentage of Wmax as a result of an increase in Vrc,p and Vrc,a. End-expiratory lung volume decreased as a result of a decrease in Vab. DeltaVrc,a/DeltaVab was constant and independent of Wmax. Thus we used DeltaVab/time as an index of diaphragm velocity of shortening. From QB to 70% Wmax, diaphragmatic pressure (Pdi) increased approximately 2-fold, diaphragm velocity of shortening 6.5-fold, and diaphragm workload 13-fold. Abdominal muscle pressure was approximately 0 during QB but was equal to and 180 degrees out of phase with rib cage muscle pressure at all percent Wmax. Rib cage muscle pressure and abdominal muscle pressure were greater than Pdi, but the ratios of these pressures were constant. There was a gradual inspiratory relaxation of abdominal muscles, causing abdominal pressure to fall, which minimized Pdi and decreased the expiratory action of the abdominal muscles on Vrc,a gradually, minimizing rib cage distortions. We conclude that from QB to 0% Wmax there is a switch in respiratory muscle control, with immediate recruitment of rib cage and abdominal muscles. Thereafter, a simple mechanism that increases drive equally to all three muscle groups, with drive to abdominal and rib cage muscles 180 degrees out of phase, allows the diaphragm to contract quasi-isotonically and act as a flow generator, while rib cage and abdominal muscles develop the pressures to displace the rib cage and abdomen, respectively. This acts to equalize the pressures acting on both rib cage compartments, minimizing rib cage distortion.

Abdominal Muscles↗

PubMed1996

Chest wall and lung volume estimation by optical reflectance motion analysis.

Estimation of chest wall motion by surface measurements only allows one-dimensional measurements of the chest wall. We have assessed on optical reflectance system (OR), which tracks reflective markers in three dimensions (3-D) for respiratory use. We used 86 (6-mm-diameter) hemispherical reflective markers arranged circumferentially on the chest wall in seven rows between the sternal notch and the anterior superior iliac crest in two normal standing subjects. We calculated the volume of the entire chest wall and compared inspired and expired volumes with volumes obtained by spirometry. Marker positions were recorded by four TV cameras; two were 4 m in front of and two were 4 m behind the subject. The TV signals were sampled at 100 Hz and combined with grid calibration parameters on a personal computer to obtain the 3-D coordinates of the markers. Chest wall surfaces were reconstructed by triangulation through the point data, and chest wall volume was calculated. During tidal breathing and vital capacity maneuvers and during CO2-stimulated hyperpnea, there was a very close correlation of the lung volumes (VL) estimated by spirometry [VL(SP)] and OR [VL(OR)]. Regression equations of VL(OR) (y) vs. VL(SP) (x, BTPS in liters) for the two subjects were given by y = 1.01x-0.01 (r = 0.996) and y = 0.96x + 0.03 (r = 0.997), and by y = 1.04x + 0.25 (r = 0.97) and y = 0.98x + 0.14 (r = 0.95) for the two maneuvers, respectively. We conclude spirometric volumes can be estimated very accurately and directly from chest wall surface markers, and we speculate that OR may be usefully applied to calculations of chest wall shape, regional volumes, and motion analysis.

Humans↗

PubMed1996

Optoelectronic techniques for patient repositioning in radiotherapy.

In modern radiotherapy practice, patient mispositionings and movements at therapy units are considered one of the major source of error in the irradiation and, consequently, a decisive factor in relapse rate and in radiation damages occurrence. Movement analysis system ELITE has been used to carry out a new conceived control on patient repositioning procedure and to implement an automatic correction of the detected position errors. Two marker disposition models have been defined for the supine position with reliable and easily identifiable body landmarks. Analytical comparison between current and reference 3D co-ordinates of these points has constituted the core of the whole method. The detection of patient's breathing phases has allowed to synchronize the co-ordinates calculation to patient's FRC, increasing accuracy and reliability of the comparison. Results point out the relative accuracy of the commonly adopted optical laser repositioning systems and confirm the significant role that ELITE can have in radiotherapy, in order to reach a suitable tradeoff between a quick irradiation set-up and a clinically correct patient irradiation.

Least-Squares Analysis↗

PubMed1996

A new method for 3D optical analysis of chest wall motion.

A method for kinematic analysis of chest wall motion is presented, based on a TV-image processor which allows a three-dimensional assessment of volume change of the trunk by automatically computing the co-ordinates of several passive markers placed on relevant landmarks of the thorax and abdomen. The parallel computation used for the image processing allows a real time recognition of the passive markers with the necessary accuracy. A geometric model also allows the on-line computation of the contribution to the chest volume by the different parts. For this purpose the model is based on 96 tetrahedrons which can be grouped into 16 compartments and into four sections representing: upper thorax (reflecting the action of neck and parasternal muscles and the effect of pleural pressure), lower thorax (reflecting the action of diaphragm and the effect of pleural and abdominal pressure), upper and lower abdomen (reflecting the actions of diaphragm and abdominal muscles). The volume can also be split into two vertical sections pointing out asymmetrics between the right and left side. The method is non-invasive, non-ionizing and leaves the subject maximum freedom of movement during the test, thus being suitable for routine clinical analysis. The monitoring of the subject can be prolonged in time and can be performed in different postures: standing, sitting, supine and lying on one side. The method was tested on eight healthy subjects showing good accuracy, reliability and reproducibility.

Biomechanical Phenomena↗

PubMed1994

Three-dimensional optical analysis of chest wall motion.

A method for kinematic analysis of chest wall motion is presented, based on a television-image processor that allows a three-dimensional assessment of volume change of the trunk by automatically computing the coordinates of several passive markers placed on relevant landmarks of the thorax and abdomen. The parallel computation used for the image processing allows for a real time recognition of the passive markers with the necessary accuracy. A geometric model also allows the online computation of the contribution to the chest volume by the different parts. For this purpose, the model presented here is based on 54 tetrahedrons that can be grouped into 9 compartments and 3 sections representing 1) upper thorax (mainly reflecting the action of neck and parasternal muscles and the effect of pleural pressure), 2) lower thorax (mainly reflecting the action of diaphragm and the effect of pleural and abdominal pressure), and 3) abdomen (mainly reflecting the actions of diaphragm and abdominal muscles). By this model, the volume can also be split into three vertical sections pointing out asymmetries between the right and left sides. The method is noninvasive, nonionizing, and leaves the subject maximum freedom of movement during the test, thus being suitable for routine clinical analysis. The monitoring of the subject can be prolonged in time and can be performed in different postures: standing, sitting, and supine. The method was tested on 12 healthy subjects showing its good accuracy, reliability, and reproducibility.

Abdomen↗