Number Of Target Points Research Articles

Stereotactic Photodynamic Therapy of Recurrent Malignant Gliomas.

In a retrospective single-center study the results of sPDT with 5-ALA in 10 patients (6 of 10 were male), aged 30 to 62 years (median: 51.5 years; 95% CI: 38-59 years) with recurrent malignant brain gliomas after standard therapy who underwent surgery during the period of 2020-2023 were analyzed. sPDT was conducted during 15 min using 5-ALA at a dosage of 20 mg/kg, a diode laser with a wavelength of 635 nm and power of 1 W, and the LFT-02-BIOSPEC unit (BIOSPEC, Russia). Three patients got repeated sPDT after 3, 7, and 15 months due to a relapse. The number of target points and the optimal position for intervention paths were determined according to the data of preoperative stereotactic MRI of the brain with contrast intensification using the CRW Precision stereotactic navigation system (Integra, USA) and intraoperative registration of the area with the highest intensity of protoporphyrin IX fluorescence along the path (according to fluorescence biospectroscopy). Glioblastoma (grade IV, WHO) was diagnosed in 7 patients, anaplastic astrocytoma (grade III, WHO) - in 3 persons. Genetic studies were performed for 9 patients, 7 of them had tumors without the IDH1 gene mutation. None of the patients had a combined 1p/19q deletion. The median volume of the contrast-enhancing part of the recurrent tumor was 7.95 cm3 (95% CI: 3.3-13.6 cm3). The median time to relapse after sPDT in patients with anaplastic astrocytomas and glioblastomas was 14.5 and 6.5 months, respectively. The median survival time after sPDT in patients with glioblastomas was 15.8 months (95% CI: 0.5-20.1 months), and in patients with anaplastic astrocytomas - 46.3 months (95%, CI not specified). In the early postoperative period, two patients had motor aphasia and hemiparesis, which further regressed. The results of a small group of patients allow to consider sPDT with 5-ALA as a promising technique to treat patients with recurrent high-grade gliomas in functionally relevant brain areas and require further prospective assessment.

Active design of diffuse acoustic fields in enclosures.

This paper presents a numerical framework for designing diffuse fields in rooms of any shape and size, driven at arbitrary frequencies. That is, we aim at overcoming the Schroeder frequency limit for generating diffuse fields in an enclosed space. We formulate the problem as a Tikhonov regularized inverse problem and propose a low-rank approximation of the spatial correlation that results in significant computational gains. Our approximation is applicable to arbitrary sets of target points and allows us to produce an optimal design at a computational cost that grows only linearly with the (potentially large) number of target points. We demonstrate the feasibility of our approach through numerical examples where we approximate diffuse fields at frequencies well below the Schroeder limit.

Efficacy and safety of conformal thermocoagulation guided by stereotactic electroencephalogram in the treatment of epilepsy caused by focal cortical dysplasia in eloquent cortex

Objective: To explore the efficacy and safety of stereotactic electroencephalography (SEEG)-guided conformal radiofrequency thermocoagulation for epilepsy caused by focal cortical dysplasia (FCD) in eloquent cortex. Methods: The data of epilepsy patients with conformal thermocoagulation in the Epilepsy Center of Guangdong Sanjiu Brain Hospital from September 2017 to August 2020 were retrospectively analyzed. SEEG electrodes were placed in patients with drug-refractory epilepsy caused by FCD in eloquent cortex with limited boundaries, which was confirmed by preoperative evaluation methods such as imaging and electroencephalography. When designing the electrode placement plan, related software was used to reconstruct the three-dimensional MRI image and lesion. SEEG electrode contacts should be designed to fully cover the lesion as much as possible. After the completion of SEEG monitoring and cortical electrical stimulation, the pre-thermocoagulation and permanent thermocoagulation modes were used in sequence. The mode of direct damage between adjacent contacts of a single electrode and cross-destruction between adjacent contacts of multiple electrodes was combined to ablate the lesions point by point. Results: A total of 22 patients were enrolled, ranging from 2 to 30 years old, with an average age of (15±9) years old. MRI showed that FCD lesions located at pre-central gyrus in 19 cases, at post-central gyrus in 3 cases, at left frontal lobe in 3 cases, at both pre-central and post-central gyrus in 1 case and at both pre-central and left frontal lobe in 2 cases. The length of the lesion was 1.2-4.0 cm, with an average length of (2.2±0.7) cm. Moreover, 7-12 SEEG electrodes were implanted, with an average of (9±2) electrodes. The number of electrodes passing through the lesion was 2-8, with an average of 5±2. The number of thermocoagulation target points was 6 to 83, with an average of 29±18, while the number of target points which proved to have function by cortical simulation was 0-21, with a median of 3.5. The number of direct thermocoagulation target points was 6 to 58, with an average of 23±13, while the number of cross thermocoagulation target points was 0 to 30, with a median of 3. The completion of the whole thermocoagulation was divided into 2 to 5 times. There were 11 cases (50%) who experienced immediate muscle strength decline, 1 case (4.5%) showed slower speech speed during thermocoagulation, 3 cases (13.6%) exhibited muscle strength decline after thermocoagulation, however, only 1 case (4.5%) had permanent hemiparalysis. There were 17 cases of Engel Ⅰ (77.3%), 3 cases of Engel Ⅱ (13.6%), and 2 case of Engel Ⅲ (9.1%), respectively, after follow-up for 6-42 months, with an average of (20±10) months. Conclusion: SEEG-guided conformal radiofrequency thermocoagulation is safe and effective for epilepsy caused by FCD in eloquent cortex with limited boundaries.

Experimental analysis and numerical optimization of a thermoplastic composite in crashworthiness

In this work, we present an experimental analysis and a numerical optimization study for the material parameter identification of an impact attenuator made of a brand new All-PP thermoplastic composite material subjected to an axial impact load. After an experimental characterization of the material, a Finite Element (FE) numerical model of the impact attenuator is created and simulated using the LS-DYNA explicit software. Subsequently, in order to capture the force-displacement trend of the crush experimental test, a fine-tuning of some relevant material parameters through surrogate-based optimization techniques is performed. The optimization process mainly consists of (1) defining a set of target points on the load-displacement curve where to evaluate the Mean Squared Error (MSE) between the numerical and the experimental values; (2) using a Design of Experiments technique to provide a sample set on which expensive deterministic simulations are performed; (3) constructing as many surrogate approximations as the number of target points in order to predict how the load values change over the parameters’ domain; (4) predicting an overall MSE surface that is optimized by means of a genetic algorithm in a sequential domain reduction iterative procedure. Results show a good agreement between the numerical and the experimental impact load and energy curves, and hence confirm that surrogate-based optimization is a valuable technique to refine the material parameters in the numerical simulation of composite structures.

Episodic ground deformation signals in Thessaly Plain (Greece) revealed by data mining of SAR interferometry time series

ABSTRACTThe Eastern Thessaly Plain presents an area of severe settlement phenomena, owing to the over-exploitation of the underground aquifer systems, causing significant damages to national infrastructures and private properties annually. Herein, both Persistent Scatterers (PS) and Small Baselines (SB) interferometric techniques were applied to study the history of ground deformation along the entire plain. Although the area consisted mostly of agricultural land, a sufficient number of point targets was obtained, well-distributed over the entire plain, permitting the recognition of spatial variations of the displacement field in addition to temporal trends. Our findings outline the southern part of the basin as the mostly affected area, whereas local subsidence patterns of lower magnitude were also recognized elsewhere. Episodes of significant ground subsidence, reaching several centimetres within a few months, characterize the deformation pattern of the area. Although average ground deformation rates do not exceed 2 cm year−1, line-of-sight (LOS) displacements of up to 13 cm were observed, occurring during the summer–autumn periods. A geographic information system (GIS)-based post-processing approach for the analysis of synthetic aperture radar (SAR) time series is presented, by which these abrupt settlement episodes can be identified in both temporal and spatial domains. The analysis allows the separation between rapid subsidence phenomena during the summer–fall season and annual deformation rates, thereby providing valuable information regarding the actual deformation pattern of the area. The results confirm in situ geological observations, highlighting the unique behaviour of the area due to intense water pumping. The study underlines that average SAR displacement rate maps might be inadequate to describe complex deformation scenarios and could lead to misinterpretations. Exploitation of the full capacity of SAR time series by detailed examination of the displacement histories, through a tailored data-mining strategy, could provide valuable information to geotechnical engineers and planners.

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Introduction: A number of target points have been used for resuscitation in severely burned patients with conflicting results. Hypothesis: The aim of our study was to evaluate the use of resuscitation guided transpulmonary thermodilution with targets lower than normal. Methods: 132 severely burned patients admitted to the critical burn care unit were included into a prospective study over a 26-month period. Cardiac index (CI), Intrathoracic blood volume (ITBV), Extravascular lung water (EVLW) and arterial blood lactates were obtained throughout the first 72h. Fluid therapy was adjusted to achieve a hourly urine output > 0.5 mL/kg, mean arterial pressure> 65 mmHg, CI >2.0 L/min/m2 and ITBV index > 750 mL/m2. When EVLW index exceeded 10 mL/kg and/or the ITBV index exceeded 1000 mL/m2 perfusion fluid was limited and vasoactive drug were introduced. Continuous variables are presented as means and standard deviations Results: 98 patients were men and 34 were female. Mean age was 48 ± 18 years, men total body surface area burned was 35.0 ± 22.1 %, mean Abbreviated Burn Severity Index was 8.2 ± 2.6 and mortality rate was 27.3%. At admission mean CI was 2.68 ± 1.06 L/min/m2 and ITBV index was 709 ± 254 mL/m2 and at 24 hours CI and ITBV index increased to 3.22 ± 1.12 L/min/m2 and to 744 ± 276 mL/m2. Arterial blood lactate decreased from 2.58 ± 2.05 mmol/L at admission to 2.45 ± 1.78 at 24 h and 1.87 ± 1.27 at 48 h. The fluid rate required to achieve targets in the first 24 hours was 5.35 ± 8.06 mL/kg/total body surface area burned (median 4.40). In the first 8 hours de mean infusion rate was 4.05, in the second 8 hours 4.7, in the third 8 hours 5.1 and at 48 h the rate decrease to 3.0 mL/kg/total body surface area burned. Conclusions: Resuscitation guided by transpulmonary thermodilution with bellow- normal targets is appropriate and requires less fluid than those calculates by Parkland formula in the first 8 hours, but after the requirementes are slightly higher.

Residual motion estimation with point targets and its application to airborne repeat-pass SAR interferometry

Due to the lack of accuracy in the navigation system, airborne repeat-pass synthetic aperture radar (SAR) interferometry (InSAR) suffers residual motion errors (RMEs). Previously, we proposed the multisquint technique with point targets (MTPT) to estimate the errors, but its implementation needs improvement and its accuracy has not been assessed by real airborne repeat-pass InSAR data. In this article, the modified MTPT is introduced first. The modification is mainly embodied in two aspects: automatic target selection and noise removing. Because the multisquint (MS) technique is also capable of estimating the RMEs in SAR interferogram and its accuracy has been verified to be high, here it is used as a comparison. In addition, from the viewpoint of MTPT, MS can be understood from another perspective. Using real X-band airborne repeat-pass SAR data, the performance of MTPT is evaluated. The experiment shows that MTPT is able to achieve high accuracy when a large number of point targets are distributed in the observed scene. The limitations of MTPT are also discussed at the end of this article.

Arterial thermodilution in burn patients suggests a more rapid fluid administration during early resuscitation

A number of target points have been used for fluid replacement in severely burned patients. The aim of our prospective randomized study was to compare the effect of two different types of fluid resuscitation regimes on the multiple organ dysfunction score (MODS) and central venous oxygen saturation (ScvO(2)) in the first 3 days after injury. Twenty-four patients admitted to the critical care unit of a university hospital with the presence of burn injury affecting more than 15% of the body surface area and in-hospital fluid resuscitation started within 3 h after burn injury were included. Patients were randomized into two groups. Fluid resuscitation was guided by the hourly urine output (HUO Group, n=12) or by the intrathoracic blood volume index (ITBVI Group, n=12). Invasive transpulmonary hemodynamic measurements utilizing pulse contour analysis with a single dilution technique and continuous ScvO(2) measurements were performed in both groups. The mean ScvO(2) was significantly lower in the HUO Group than in the ITBVI Group (P=0.024) for the first 24 h. MODS was significantly higher in the HUO Group than in the ITBVI group 48 h (P=0.024) and 72 h after injury (P=0.014). The two main outcome parameters, i.e., MODS calculated at 48 and 72 h after injury and ScvO(2) were negatively correlated on day 1 (r=-0.684, P=0.004, r=-0.677, P=0.003). There were no statistical differences in clinical outcome parameters. Our data suggest that ITBVI may be a better target parameter than HOU in the fluid resuscitation of severely burned patients after injury.

Photogrammetric monitoring of deformation caused by mine subsidence

Abstract A photogrammetric survey was carried out in the Lithgow area of New South Wales, approximately 150 km west of Sydney, to monitor the movement of rock masses under the influence of longwall mining. The task was to determine three dimensional coordinates of a number of target points on the subject rock masses with respect to time, such that the rock movements could be modelled as the longwall face passed below. The exercise was carried out as a student project and was supervised by university academic staff. In the area of interest, it was anticipated that both subsidence and lateral movements would be in the order of one metre. Accuracy requirement was in the order of 0.1 metres. The photography was undertaken from 14–23 December, 1993 inclusive, hourly from 8 a.m. to 6 p.m. with a further session on January 20, 1994. Both 35 mm (Canon AE-1) and 70 mm (semi-metric Hasselblad 500 ELM) cameras were used. A comparison was made between the results achieved from both photographic formats.

Distribution of number of point targets killed and higher moments of coverage of area targets

AbstractThe coverage C of area targets by salvos of weapons generally varies randomly, because of random target location and weapon impact point fluctuations. A third source of variation appears when, instead of an area target, a multiple‐element target is considered, consisting of m point targets distributed randomly and independently of one another around the target center. A multiple‐integral expression is derived for the probability pk of killing exactly k target elements. It is shown that pk is a linear function of the higher moments, of the order k to m, of the area coverage C. More explicit expressions are derived for the case of two weapons and for circular‐symmetric functions. Similar to well‐known results for the expectation and variance of coverage of area targets, these expressions can be evaluated by numerical quadrature. Furthermore, the coverage problem in which all underlying functions are Gaussian can be completely solved in closed form. For such a problem, with two weapons, numerical results are presented. They show that the distribution of k can be approximated by a binomial distribution only if the target center and weapon impact point fluctuations are small.