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Biomedical subjects

G Ferrigno

Publications and source records attributed to G Ferrigno.

47 records · Page 3Linked to original sources
PubMed1994

[Experiences with sclerostomy with the Holmium laser].

The THC-YAG laser (holmium laser) war used to perform ab externo sclerostomies in patients affected by various types of glaucoma. This approach was employed in 48 eyes with diagnoses of medically uncontrolled chronic open angle glaucoma, plateau iris or neovascular glaucoma. Post-operatively, 5-FU was injected. At the tend of the follow-up (mean 10.22 +/- 3.4 months), in 25 eyes (52.1%) the IOP was under control without medical therapy. In 12 eyes (25.0%) it was necessary to use antiglaucomatous topical therapy, and in 11 eyes (22.9%) the IOP was uncontrolled despite therapy. The authors stress the importance of a correct pharmacological protocol before and after operation and describe the surgical technique. They confirm the validity of this approach, owing to its minical invasiveness, the possibility of repeating the procedure, and the low complication rate.

Aged↗
PubMed1992

Comparison between the more recent techniques for smoothing and derivative assessment in biomechanics.

When analysing and evaluating human motion, two strictly interconnected problems arise: the data smoothing and the determination of velocities and accelerations from displacement data. Differentiating procedures magnify the noise superimposed on the useful kinematic data. A smoothing procedure is thus required to reduce the measurement noise before the differentiation can be carried out. In the paper two techniques for derivative assessment are presented, tested and compared. One of these is the procedure known as one of the best automatic smoothing and differentiating techniques: generalised cross validatory spline smoothing and differentiation (GCVC). The other, which has recently been presented, features an automatic model-based bandwidth-selection procedure (LAMBDA). The procedures have been tested with signals presented by other authors and available in the literature, by test signals acquired using the ELITE motion analyser and by synthetic data. The results show better or similar performance of LAMBDA compared with GCVC. In the cases in which the natural conditions at the signal boundaries are not met GCVC gives bad results (especially on the third derivative) whereas LAMBDA is not affected at all. Moreover, analysis time is dramatically lower for LAMBDA.

Biomechanical Phenomena↗
PubMed1990

Technique for the evaluation of derivatives from noisy biomechanical displacement data using a model-based bandwidth-selection procedure.

Smoothing and differentiation of noisy signals are common problems whenever it is difficult or impossible to obtain derivatives by direct measurement. In biomechanics body displacements are frequently assessed and these measurements are affected by noise. To avoid high-frequency noise magnification, data filtering before differentiation is needed. In the approach reported here an autoregressive model is fitted to the signal. This allows the evaluation of the filter bandwidth and the extrapolation of the data. The extrapolation also reduces edge effects. Low-pass filtering is performed in the frequency domain by a linear phase FIR filter and differentiation is performed in the frequency domain. The reported results illustrate the accuracy of the algorithm and its speed (mainly due to the use of the FFT algorithm). Automatic bandwidth selection also guarantees the homogeneity of the results.

Algorithms↗
PubMed1990

An algorithm for 3-D automatic movement detection by means of standard TV cameras.

An algorithm for the computation of 3-D coordinates (space intersection) of marked points on a moving subject surveyed by a couple of TV cameras is presented herein. It has been designed in order to meet the requirements of routinary analysis in biomechanic laboratories. 3-D geometrical arrangement of the TV cameras (space resection) is obtained by means of a method which is based on an iterative least-squares estimation and requires little time for calibration operations; 3-D coordinates are computed by means of a fast geometrical intersection algorithm. The whole algorithm has been extensively used in different laboratories and results on its reliability and accuracy are reported.

Algorithms↗
PubMed1987

Changes in spatial scale in drawing and handwriting: kinematic contributions by proximal and distal joints.

The coordination of arm and hand motions was studied in tasks involving drawing and handwriting movements of different amplitudes. To this end, pen motion was recorded by means of a digitizing table, while the positions of different markers on the limb were monitored by the ELITE system. It was found that the amplitude of shoulder and elbow angular motions scales roughly with the size of the figure drawn or of the script, whereas the amplitude of wrist and finger motions is small, independent of size. Consequently, the larger the limb movement, the smaller the magnitude of the contributions by motions at distal joints relative to that at proximal joints. Furthermore, while shoulder and elbow motions are tightly coupled (constant phase relation), motions at distal joints are loosely coupled to those at the proximal joints (variable phase relation). On the other hand, motion at distal joints increases the accuracy of the movement, as indicated by the smaller variability of pen trajectories compared to that of wrist trajectories.

Art↗
PubMedDate not supplied

Evaluation of theories of complex movement planning in different levels of gravity.

Due to high redundancy of degrees of freedom in the human body, we can perform any movement, from the simplest to the most complex, in many different ways. Several studies are still trying to identify the motor strategies that master this redundancy and generate the movements whose characteristics are highly stereotyped. The aim of this work is to build a simulator that is able to evaluate different motor planning hypotheses. The most interesting applications of this tool occur in studies of the motor strategy in microgravity conditions. The comparison between simulated movements and kinematics data recorded both on Earth, and during a 5-month mission on board the Mir station shows that for a complex whole-body movement (such as trunk bending) a single planning criterion cannot explain all movement aspects. However, the simulator allows an understanding of the motor planning adaptation of astronauts. In space, the lack of equilibrium constraint (which on Earth brings about the center of mass control) leads to a new motor strategy that minimizes dynamic interactions with the floor.

Adaptation, Physiological↗
PubMedDate not supplied

Motor coordination in weightless conditions revealed by long-term microgravity adaptation.

The functional approach to studying human motor systems attempts to give a better understanding of the processes behind planning movements and their coordinated performance by relying on weightlessness as a particularly enlightening experimental condition. Indeed, quantitative monitoring of sensorimotor adaptation of subjects exposed to weightlessness outlines the functional role of gravity in motor and postural organization. The recent accessibility of the MIR Space Station has allowed for the first time experimental quantitative kinematic analysis of long-term sensorimotor and postural adaptation to the weightless environment though opto-electronic techniques. In the frame of the EUROMIR'95 Mission, two protocols of voluntary posture perturbation (erect posture, EP; forward trunk bending, FTB) were carried out during four months of microgravity exposure. Results show that postural strategies for quasistatic body orientation in weightlessness are based on the alignment of geometrical body axes (head and trunk) along external references. A proper whole body positioning appears to be recovered only after months of microgravity exposure. By contrast, typically, terrestrial strategies of co-ordination between movement and posture are promptly restored and used when performing motor activities in the weightless environment. This result is explained under the assumption that there may be different sensorimotor integration processes for static and dynamic postural function and that the organisation of coordinated movement might rely stably on egocentric references and kinematics synergies for motor control.

Adaptation, Physiological↗
PubMedDate not supplied

Quantitative analysis of motion control in long term microgravity.

In the frame of the 179-days EUROMIR '95 space mission, two in-flight experiments have foreseen quantitative three-dimensional human movement analysis in microgravity. For this aim, a space qualified opto-electronic motion analyser based on passive markers has been installed onboard the Russian Space Station MIR and 8 in flight sessions have been performed. Techhology and method for the collection of kinematics data are described, evaluating the accuracy in three-dimensional marker localisation. Results confirm the suitability of opto-electronic technology for quantitative human motion analysis on orbital modules and raise a set of "lessons learned", leading to the improvement of motion analyser performance with a contemporary swiftness of the on-board operations. Among the experimental program of T4, results of three voluntary posture perturbation protocols are described. The analysis suggests that a short term reinterpretation of proprioceptive information and re-calibration of sensorimotor mechanisms seem to end within the first weeks of flight, while a continuous long term adaptation process allows the refinement of motor performance, in the frame of never abandoned terrestrial strategies.

Adaptation, Physiological↗
PubMedDate not supplied

[Automatic opto-electronic control of patient position in radiotherapy for breast carcinoma].

INTRODUCTION: We report on the technical and clinical validation of a system for real-time analytical control of patient position at simulation and treatment units in radiotherapy. MATERIAL AND METHODS: The positioning control system uses a technology for motion analysis consisting of an optical component (a pair of TV cameras) and of a unit for real-time image processing. The system can provide real-time (up to 100 times a second) three-dimensional (3D) coordinates of a set of passive markers (small plastic hemispheres, 5 mm O) previously positioned on the patient and located within the field of view of the system's TV cameras. The method for positioning quality control is based on the analytical comparison between the current positions of the set of markers placed on the patient's skin and a corresponding reference pattern, the latter acquired at the end of the simulation procedure or at the first irradiation session. The system was used at the Radiotherapy Division of the European Institute of Oncology for the analytical control of repositioning in three patients submitted to irradiation after conservative surgery (quadrantectomy) for breast cancer. This showed the clinical feasibility of both the technology and the method, and permitted to quantify improvement in patient positioning relative to current repositioning procedures. In particular, the possibility to evaluate the patient's breathing phases allowed to distinguish the different factors (repositioning inaccuracies and cyclic and random patient movements) contributing to global localization errors. RESULTS: This method is independent of physical and geometrical irradiation parameters and permits efficient real-time quantitative control of specific repositioning quality and of actual patient immobility during irradiation. Assessment of the accuracy of conventional repositioning methods based on laser alignment showed a fair performance of the optical centering procedure (with 3D displacements < 5 mm) only for the markers placed close to the skin landmarks used for laser alignment. On the contrary, the markers within the irradiation field but not directly controlled during the repositioning procedure exhibited localization errors > 5 mm; this happened even though the inaccuracies related to patient's breathing movements had been excluded from analysis. Moreover, quantitative assessment of global localization errors confirmed the high influence of breathing movements on the position repeatability and maintenance. In this case, even the markers which were on average well repositioned turned out to be significantly displaced during the radiation dose delivery. CONCLUSIONS: Our results confirm that real-time motion analysis based on opto-electronic techniques can play a crucial role as a means of improving patient positioning and assessing immobility. Thus, the system permits to quantify errors in target volume localization, which permits to adopt suitable countermeasures to reduce uncertainties during actual irradiation. This is a crucial requirement, particularly when the complexity of the irradiation geometry (conformal radiotherapy) or radiation type (hadrontherapy) calls for optimal application of the simulated treatment plan to each actual irradiation session.

Breast Neoplasms↗