Tangential Imaging Research Articles

Development of an Auxiliary Device for Patellar and Femoral Joint Tangential Axial Radiographic Imaging and a Method for Obtaining an Optimal Radiographic Image Using the Development.

This study evaluated the accuracy of tangential axial radiography of the patellar and femoral joint using an auxiliary device based on three image evaluation criteria, which we named the patellofemoral joint radiography auxiliary device (PJR). To compare the PJR method with conventional radiographic methods, such as Laurin, Merchant, and Settegast, a whole-body phantom (PBU-31) was used and three image evaluation items were set. The radiographic method, the smallest inclination of the patellar and showed the best half lateral image of the patella, is Settegast, and the measurement is 9.40. The second-best PJR measurement is 9.97, and the difference between the two measures is 5.76% (p = 0.001). The radiographic method showing the image with the largest distance between the patellar and femoral joint space is PJR which a measurement is 12.35. The second best Merchant measure is 10.55, and the difference between the two measures is 14.54% (p = 0.001). The method in which the two bones were well overlapped (i.e., evaluate the distortion of the image by measured as the distance between the femoral trochlear groove and the tibial tuberosity) is the PJR and the measurement is −0.37. The second-best Merchant measure is 3.93, and the difference between the two measures is 91.4% (p = 0.001). The Settegast has the image with the smallest inclination of the patella, but the PJR has the image that best describes the patellar–femoral joint and the least distortion of the image. As a result of the comprehensive evaluation, when using PJR, bending the knee by 40° and setting a 140° angle between the long axis of the femur and the long axis of the lower leg were considered to be the most beneficial conditions. Therefore, we propose the use of PJR for tangential axial radiography of the patellar–femoral joint.

The application of the 150° oblique tangential fluoroscopic view to detect the posterosuperior femoral neck screw in–out–in intraoperatively

This study investigates the application of the 150° tangential fluoroscopic projection as a novel fluoroscopic view to detect the posterosuperior screw in–out–in (IOI) in the cannulated screws fixation of femoral neck fractures. A retrospective analysis was conducted including 33 patients with femoral neck fractures enrolled from April to November 2021. All patients underwent closed reduction and internal fixation with cannulated screws under intra-operative C-arm fluoroscopy. The posterosuperior femoral neck screw position (whether in–out–in and the distance to the femoral neck cortex) was evaluated from the standard anteroposterior (AP), lateral view, and tangential view images. Postoperative computed tomography (CT) scan results are considered the gold standard for detecting the femoral neck screw locations. Of 33 patients, no femoral neck screws were found to be placed IOI under the standard AP and lateral views. The tangential view revealed the posterosuperior screw was IOI in 8 patients, whereas the average distance between the posterosuperior screw and the posterior femoral neck cortex was 2.73 ± 1.06 mm under the standard lateral view. Postoperative CT verified that posterosuperior screw was placed IOI in these 8 patients. In the other 25 patients with the tangential view showed the posterosuperior screw completely contained in the femoral neck, the average distance between the posterosuperior screw and the posterior femoral neck cortex was 5.48 ± 1.26 mm under the standard lateral view and 2.76 ± 1.08 mm under the tangential view, with a statistically significant difference between the two groups (p < 0.05). Post-operative CT demonstrated that the femoral neck screws were completely contained in the femoral neck in these 25 patients. Intra-operative tangential view of 150° can effectively identify the posterosuperior screw IOI in the cannulated screws fixation of femoral neck fractures. Based on our study, we highly recommend the tangential view as a routine intraoperative fluoroscopic angle to detect the posterosuperior screw IOI.

Patient setup accuracy in DIBH radiotherapy of breast cancer with lymph node inclusion using surface tracking and image guidance.

Studying setup accuracy in breast cancer patients with axillary lymph node inclusion in deep inspiration breath-hold (DIBH) after patient setup with surface-guided radiotherapy (SGRT) and image-guided radiotherapy (IGRT). Breast cancer patients (N = 51) were treated (50 Gy in 25 fractions) with axillary lymph nodes within the planning target volume (PTV). Patient setup was initiated with tattoos and lasers, and further adjusted with SGRT. The DIBH guidance was based on SGRT. Orthogonal and/or tangential imaging was analyzed for residual position errors of bony landmarks, the breath-hold level (BHL), the skin outline, and the heart; and setup margins were calculated for the PTV. The calculated PTV margins were 4.3 to 6.3 and 2.8 to 4.6 mm before and after orthogonal imaging, respectively. The residual errors of the heart were 3.6 ± 2.2 mm and 2.5 ± 2.4 mm before and 3.0 ± 2.5 and 2.9 ± 2.3 mm after orthogonal imaging in the combined anterior-posterior/lateral and the cranio-caudal directions, respectively, in tangential images. The humeral head did not benefit from daily IGRT, but SGRT guided it to the correct location. We presented a slightly complicated but highly accurate workflow for DIBH treatments. The residual position errors after both SGRT and IGRT were excellent compared to previous literature. With well-planned SGRT, IGRT brings only slight improvements to systematic accuracy. However, with the calculated PTV margins and the number of outliers, imaging cannot be omitted despite SGRT, unless the PTV margins are re-evaluated.

Identification of tree species from the Peruvian tropical amazon “Selva Central” forests according to wood anatomy

The “Selva Central” of Peru is characterized by its forest species richness that produces quality wood for countless uses. Therefore, it is necessary to identify the wood and its macroscopic anatomy, which is an important tool for the botanical identification of tree species. For this purpose, 13 sawmills located in 3 provinces were selected that exploit several tree species of “Selva Central”. Sampling of representative woods was carried out, identified by common names and, in the laboratory, they were polished, examined, and grouped by the similarity of the macroscopic anatomical structure, leading to the tree species identification. Twenty tree species were identified, belonging to 17 genera, with emphasis on the Lauraceae and Fabaceae families. However, Moraceae, Meliaceae, Lecythidaceae, Euphorbiaceae, Bignoniaceae, Myristicaceae, Combretaceae, and Burseraceae families were also identified. The anatomical structures of all the identified tree species were described, transversal and longitudinal tangential cross section images were collected, and a species identification key was constructed. The implications and importance of tree species identification via wood anatomy were discussed, in terms of controlling forest exploitation, traceability of the production chain, and the future development of an artificial intelligence tree-species identification method.

Van der Waals Interactions of Moving Particles with Surfaces of Cylindrical Geometry

General nonrelativistic theory has been developed and the expressions obtained for the tangential (dissipative) and radial (conservative) image forces and van der Waals forces (vdW) acting on charged and neutral particles when they move parallel to the axis of a cylinder with circular cross-section, or in the space between coaxial cylinders. Numerical calculations of vdW forces have been performed for metal (Au) and dielectric (Si) materials of cylinders (filaments) and Cs atoms at velocities ~107m/s. A remarkable result is that in the case of metal cylinders (atomic filaments and chains) the dynamic vdW potential can be repulsive for certain values of the velocity–distance parameter and the characteristic atomic frequency. In the case of a Si material, the dynamic vdW potential increases relative to the static one (by modulus) when the velocity–distance parameter Vω0/R changes from zero to ~1.3 and then tends to zero.

Comparison of three differently shaped ROIs in free breathing breast radiotherapy setup using surface guidance with AlignRT®.

Setup accuracy within adjuvant radiotherapy of breast cancer treated in free breathing is well studied, but a comparison of the typical regions of interest (ROI) used in surface guided radiation therapy (SGRT) does not exist. The aim of this study was to estimate the setup accuracy obtained with differently shaped ROIs in SGRT. A total of 573 orthogonal image pairs were analyzed from free breathing breast patients in two groups: positioning using AlignRT® surface guidance system (Group A, n = 20), and setup using conventional laser and tattoo setup (Group L, n = 20). For SGRT, three different setup ROIs were used: a Breast-shaped, O-shaped and T-shaped (B-O and T-ROI). We evaluated the isocenter-, rotation-, pitch and arm position accuracy and residual errors for the chest wall and shoulder joint in kV orthogonal and tangential setup images with laser- or SGRT-based setup. Less isocenter variance was found in Group A than in Group L. Rotations and posture errors were larger in group L than in Group A (p ≤ 0.05). Rotation error was smaller with T-shaped ROI than with O- or B-shape (p = 0.01-0.04). Setup with AlignRT® improves reproducibility compared to laser setup. Between the different ROI shapes only small differences were found in the patient posture or the isocenter position in the images. The T-ROI is recommended to set up the chest wall bony structure and an additional B-ROI may be used to fine-tune the soft tissue accuracy.

Modified forms of Tscherning ellipses.

Third-order equations are well known for determining sagittal and tangential powers of a thin lens, corresponding to an eye rotating behind a lens to view objects away from the optical axis of the lens. These equations are referenced to the back surface of the lens and do not take into account the peripheral thickness of the lens. They do not give the same results as finite raytracing at small angles in which powers are referenced to the vertex sphere, which is the same distance from the centre-of-rotation for all object angles. Modified forms of the third-order sagittal and tangential image vergence error equations are developed to overcome the discrepancies. These are used to determine Tscherning ellipses for zero oblique astigmatism and zero mean oblique power error. While solutions to oblique astigmatism are not affected by the modifications, there are considerable changes to mean oblique error solutions.

Aberrations of plane-symmetrical mirror systems with freeform surfaces. Part II: closed-form aberration formulas.

The aberrations of reflective optical systems with planar symmetry are investigated in the most general case, with freeform surfaces and possibly different locations of the tangential and sagittal object and image. In this second and last paper, closed-form expressions are derived for the aberrations created by an individual mirror. We study two-mirror off-axis telescopes and establish a new family of designs that we show is simultaneously free of constant coma, linear astigmatism, and quadratic distortions (including smile and keystone). Analytical expressions for the intrinsic aberrations of an astigmatic beam are also derived.

Aberrations of plane-symmetrical mirror systems with freeform surfaces. Part I: generalized ray-tracing equations.

The aberrations of reflective optical systems with one plane of symmetry are investigated in the most general case, with freeform surfaces and possibly different locations of the tangential and sagittal object and image. In this first paper in a series of two, we establish generalized ray-tracing equations including transverse aberrations up to the third order in ray coordinates. The ray-tracing treatment allows us to overcome difficulties linked to the non-existence of a suitable astigmatic wavefront reference. The obtained expressions can describe multi-mirror systems and include all induced aberration terms. As an illustration, a simple freeform off-axis mirror is analyzed.

Investigation of argon transport by X-Ray imaging crystal spectrometer on J-TEXT

• A tangential XICS has been upgraded and the temporal evolution of Ar density were observed by XICS on J-TEXT. • The behavior of argon was investigated under different discharge conditions. • STRAHL simulation results showed that the convection velocity changed from negative to positive as the ne increased. A tangential X-ray imaging crystal spectrometer (XICS) has been upgraded in the J-TEXT tokamak. The XICS system has been used to measure ion and electron temperature, plasma rotation velocities, selected impurity densities, and can be used for impurity transport. The XICS on J-TEXT was designed to receive Ar XVII emissions from the -0.5 a to +0.5 a region with a spatial resolution of 1.8 cm in the vertical direction, a is the minor radius. The temporal evolution of argon impurity density profiles after an argon gas puffed were observed with a time resolution of up to 2 ms. The behaviour of argon was investigated under different discharge conditions. The experimental results show that, as the density increased, the impurity confinement time obviously increased. Simulation results obtained by STRAHL showed that the convection velocity changed from negative to positive as the electron density increased. This indicated that impurities moved more favourably toward the plasma boundary.

Computer-assisted timber identification based on features extracted from microscopic wood sections

Abstract Wood anatomy is one of the most important methods for timber identification. However, training wood anatomy experts is time-consuming, while at the same time the number of senior wood anatomists with broad taxonomic expertise is declining. Therefore, we want to explore how a more automated, computer-assisted approach can support accurate wood identification based on microscopic wood anatomy. For our exploratory research, we used an available image dataset that has been applied in several computer vision studies, consisting of 112 — mainly neotropical — tree species representing 20 images of transverse sections for each species. Our study aims to review existing computer vision methods and compare the success of species identification based on (1) several image classifiers based on manually adjusted texture features, and (2) a state-of-the-art approach for image classification based on deep learning, more specifically Convolutional Neural Networks (CNNs). In support of previous studies, a considerable increase of the correct identification is accomplished using deep learning, leading to an accuracy rate up to 95.6%. This remarkably high success rate highlights the fundamental potential of wood anatomy in species identification and motivates us to expand the existing database to an extensive, worldwide reference database with transverse and tangential microscopic images from the most traded timber species and their look-a-likes. This global reference database could serve as a valuable future tool for stakeholders involved in combatting illegal logging and would boost the societal value of wood anatomy along with its collections and experts.

Diagnosis of dorsal screw penetration after volar plating of a distal radial fracture.

The aim of this study was to investigate whether intraoperative 3D fluoroscopic imaging outperforms dorsal tangential views in the detection of dorsal cortex screw penetration after volar plating of an intra-articular distal radial fracture, as identified on postoperative CT imaging. A total of 165 prospectively enrolled patients who underwent volar plating for an intra-articular distal radial fracture were retrospectively evaluated to study three intraoperative imaging protocols: 1) standard 2D fluoroscopic imaging with anteroposterior (AP) and elevated lateral images (n = 55); 2) 2D fluoroscopic imaging with AP, lateral, and dorsal tangential views images (n = 50); and 3) 3D fluoroscopy (n = 60). Multiplanar reconstructions of postoperative CT scans served as the reference standard. In order to detect dorsal screw penetration, the sensitivity of dorsal tangential views was 39% with a negative predictive value (NPV) of 91% and an accuracy of 91%; compared with a sensitivity of 25% for 3D fluoroscopy with a NPV of 93% and an accuracy of 93%. On the postoperative CT scans, we found penetrating screws in: 1) 40% of patients in the 2D fluoroscopy group; 2) in 32% of those in the 2D fluoroscopy group with AP, lateral, and dorsal tangential views; and 3) in 25% of patients in the 3D fluoroscopy group. In all three groups, the second compartment was prone to penetration, while the postoperative incidence decreased when more advanced imaging was used. There were no penetrating screws in the third compartment (extensor pollicis longus groove) in the 3D fluoroscopy groups, and one in the dorsal tangential views group. Advanced intraoperative imaging helps to identify screws which have penetrated the dorsal compartments of the wrist. However, based on diagnostic performance characteristics, one cannot conclude that 3D fluoroscopy outperforms dorsal tangential views when used for this purpose. Dorsal tangential views are sufficiently accurate to detect dorsal screw penetration, and arguably more efficacious than 3D fluoroscopy. Cite this article: Bone Joint J 2020;102-B(7):874-880.

Dynamic Multi-Sensor Platform for Efficient Three-Dimensional-Digitalization of Cities

Abstract Three-dimensional urban reconstruction requires the combination of data from different sensors, such as cameras, inertial systems, GPS, and laser sensors. In this technical report, a complete system for the generation of textured volumetric global maps (deep vision) is presented. Our acquisition platform is terrestrial and moves through different urban environments digitizing them. The report is focused on describing the three main problems identified in this type of works. (1) The acquisition of three-dimensional data with high precision, (2) the extraction of the texture and its correlation with the 3D data, and (3) the generation of the surfaces that describe the components of the urban environment. It also describes the methods implemented to extrinsically calibrate the acquisition platform, as well as the methods developed to eliminate the radial and tangential image distortion; and the subsequent generation of a panoramic image. Procedures are developed for the sampling of 3D data and its smoothing. Subsequently, the process to generate textured global maps with a negligible uncertainty is developed and the results are presented. Finally, the process of surface generation and the post-process of eliminating certain holes/occlusions in the meshes are reported. In each section, results obtained are shown. Using the methods presented here for geometric and photorealistic reconstruction of urban environments, high-quality 3D models are generated. The results achieved the following objectives: generate global textured models that preserve the geometry of the scanned scenes.

Inversion of Smoke Black Concentration Field in a Tangentially Fired Furnace Based on Super-Resolution Reconstruction

The tangentially fired furnace has the advantages of sufficient combustion and low NOx emission, and the smoke black concentration in the furnace reflects the combustion situation of combustion equipment. The flame field and smoke black concentration field in the furnace are complex, so it is meaningful to study the flame field and the smoke black concentration field of the tangential furnace. In this article, the visual method was used to reconstruct the flame and smoke black concentration fields in the furnace. Due to the low resolution of industrial cameras, the final reconstruction effect is limited. Given this situation, this article proposes a strengthen edge characteristic super-resolution network (SECSR) algorithm suitable for the tangentially fired furnace flame images. The flame edge processing is added to the depth neural network, which enhances the ability of flame edge feature extraction. It constructs a generative adversarial network which can greatly improve the resolution of furnace flame image, to obtain high-resolution tangential furnace flame image. Secondly, based on the high-quality flame image, this article proposes an inversion algorithm of the black concentration field of the tangentially fired furnace smoke. The algorithm obtains the high-precision tangentially furnace flame temperature field through an inversion calculation to calculate the soot concentration field. In the future work, we will predict the variation trend of smoke black concentration in the furnace through the results of the inversion calculation model, to understand the combustion situation in the furnace and control the fuel consumption to reduce smoke black emission, which has important guiding significance for protecting the environment and saving resources.

Two families of elliptical plasma lenses

ABSTRACT Plasma lensing is the refraction of low-frequency electromagnetic rays due to free electrons in the interstellar medium. Although the phenomenon has a distinct similarity to gravitational lensing, particularly in its mathematical description, plasma lensing introduces other additional features, such as wavelength dependence, radial rather than tangential image distortions, and strong demagnification of background sources. Axisymmetrical models of plasma lenses have been well studied in the literature, but density distributions with more complicated shapes can provide new and exotic image configurations and increase the richness of the magnification properties. As a first step towards non-axisymmetrical distributions, we study two families of elliptical plasma lens, softened power law, and exponential plasma distributions. We perform numerical studies on each lens model, and present them over a parameter space. In addition to deriving elliptical plasma lens formulae, we also investigate the number of critical curves that the lens can produce by studying the lens parameter space, in particular the dependence on the lensing ellipticity. We find that the introduction of ellipticity into the plasma distribution can enhance the lensing effects as well as the complexity of the magnification map.

AlignRT® and Catalyst™ in whole-breast radiotherapy with DIBH: Is IGRT still needed?

PurposeSurface guided radiotherapy (SGRT) is reported as a feasible setup technique for whole‐breast radiotherapy in deep inspiration breath hold (DIBH), but position errors of bony structures related to deeper parts of the target are not fully known. The aim of this study was to estimate patient setup accuracy and margins obtained with two different SGRT workflows with and without daily kV‐ and/or MV‐based image guidance (IGRT).MethodsA total of 50 breast cancer patients were treated in DIBH, using SGRT for the patient setup, and IGRT for isocenter corrections. The patients were treated at two different departments, one using AlignRT® (25 patients) and the other using Catalyst™ (25 patients). Inter‐fractional position errors were analyzed retrospectively in orthogonal and tangential setup images, and analyzed with and without IGRT.ResultsIn the orthogonal kV‐kV images, the systematic residual errors of the bony structures were ≤ 3 mm in both groups with SGRT‐only. When fine‐adjusted by daily IGRT, the errors decreased to ≤ 2 mm; except for the shoulder joint. The residual errors of the ribs in tangential images were between 1 and 2 mm with both workflows. The heart planning margins were between 3 and 7 mm.ConclusionsThe frequency of IGRT may be considerably reduced with a well‐planned SGRT‐workflow for whole‐breast DIBH with residual errors ≤ 3 mm. This accuracy can be further improved with an IGRT scheme.

The Impulse Response of Negatively Focused Spherical Ultrasound Detectors and Its Effect on Tomographic Optoacoustic Reconstruction.

In optoacoustic tomography, negatively focused detectors have been shown to improve the tangential image resolution without sacrificing sensitivity. Since no exact inversion formulas exist for optoacoustic image reconstruction with negatively focused detectors, image reconstruction in such cases is based on using the virtual-detector approximation, in which it is assumed that the response of the negatively focused detector is identical, up to a constant time delay, to that of a point-like detector positioned in the detector's center of curvature. In this paper, we analyze the response of negatively focused spherical ultrasound detectors in three dimensions and demonstrate how their properties affect the optoacoustic reconstruction. Our analysis sheds new light on commonly reported experimental reconstruction artifacts in optoacoustic systems that employ negatively focused detectors. Based on our analysis, we introduce a simple correction to the virtual-detector approximation that significantly enhances image contrast and reduces artifacts.

Theoretical Study of Refraction Effects of Plano Ophthalmic Prisms

Nominally plano prisms can have appreciable refractive errors that exceed the usual prescribing step of 0.25 D, particularly when an eye rotates to view off-axis objects. The purpose of this study was to determine theoretically the refractive power effects of nominally plano-refracting power prisms. Plano prisms with zero refraction were designed for the as-worn condition. A basic method was developed to determine refractive effects in the presence of pantoscopic tilt. A refined method was developed that considers the eye rotating behind the lens, and this and the basic method were compared with accurate raytracing. Plano prisms of 4 and 8 Δ were designed with astigmatic back surfaces to compensate for oblique incidence, and tangential and sagittal image vergence errors were investigated for base-up (BU) and base-down (BD) directions, 0 and -3.33 D object vergences, and pantoscopic tilts up to 10°. Basic and refined results did not differ from accurate results by more than 0.04 and 0.08 D, respectively. Errors for 8 Δ prisms were approximately twice those for 4 Δ prisms. Errors were approximately proportional to tilt. With 10° tilt, the errors ranged between -0.65 D/-0.23 D (8 Δ BD, -3.33 D object vergence) and +0.36 D/+0.15 D (8 Δ BU, 0 D object vergence). Sagittal errors were generally about one third of corresponding tangential errors. In the presence of tilt, BU prisms had positive errors, and BD prisms had similar, but negative, errors for distance objects. At -3.33 D object vergence with tilt, negative errors for BD were greater than positive errors for BU. When the eye rotates to look at objects at different positions, errors can increase beyond those occurring on-axis. When designed for nontilted conditions, but then subjected to tilt or to viewing off-axis objects, plano prisms can have errors exceeding the usual prescribing step of 0.25 D.

Optimal selection of optimization bolus thickness in planning of VMAT breast radiotherapy treatments

The aim of this study was to find an optimal optimization skin flash thickness in volumetric modulated arc radiotherapy of the breast in consideration of soft tissue deformations during the treatment course. Ten breast radiotherapy patients with axillary lymph node inclusion were retrospectively planned with volumetric modulated arc radiotherapy technique. The plans were optimized with the planning target volume (PTV) extending outside the skin contour by 0, 5, 7, and 10 mm; and with optimization boluses of 3 or 5 mm on the extended PTV. The final dose was calculated without the bolus. The plans were compared in terms of PTV homogeneity and conformity, and dose minima and maxima. The doses to organs at risk were also evaluated. The doses were recalculated in real patient geometries based on cone beam computed tomography (CBCT) images captured 3 to 6 times during each patient's treatment course. The optimization to the PTV without the PTV extension resulted in the best CTV coverage in the original plans (V95% = 98.0% ± 1.2%). However, when these plans were studied in real CBCT-based patient geometries, the CTV V95% was compromised (94.6% ± 8.3%). In addition, for the surface (4 mm slap inside the PTV 4 mm below the body contour) dose V95% was reduced from the planned 74.7% ± 7.5% to the recalculated 65.5% ± 11.5%. Optimization with an 8-mm bolus to a PTV with 5-mm extension was the most robust choice to ensure the CTV and surface dose coverage (recalculated V95% was 95.2% ± 6.4% and 74.6% ± 8.4%, respectively). In cases with the largest observed deformations, even a 10-mm PTV extension did not suffice to cover the target. Optimization with a 5-mm PTV extension and an 8-mm optimization bolus improved the surface dose and slightly improved the CTV dose when compared to no extension plans. For deformations over 1 cm, no benefit was seen in PTV extensions and replanning is recommended. Frequent tangential and CBCT imaging should be used during treatment course to detect potential large anatomical changes.

Extraction of multi-scale landslide morphological features based on local Gi* using airborne LiDAR-derived DEM

For automatic landslide detection, landslide morphological features should be quantitatively expressed and extracted. High-resolution Digital Elevation Models (DEMs) derived from airborne Light Detection and Ranging (LiDAR) data allow fine-scale morphological features to be extracted, but noise in DEMs influences morphological feature extraction, and the multi-scale nature of landslide features should be considered. This paper proposes a method to extract landslide morphological features characterized by homogeneous spatial patterns. Both profile and tangential curvature are utilized to quantify land surface morphology, and a local Gi* statistic is calculated for each cell to identify significant patterns of clustering of similar morphometric values. The method was tested on both synthetic surfaces simulating natural terrain and airborne LiDAR data acquired over an area dominated by shallow debris slides and flows. The test results of the synthetic data indicate that the concave and convex morphologies of the simulated terrain features at different scales and distinctness could be recognized using the proposed method, even when random noise was added to the synthetic data. In the test area, cells with large local Gi* values were extracted at a specified significance level from the profile and the tangential curvature image generated from the LiDAR-derived 1-m DEM. The morphologies of landslide main scarps, source areas and trails were clearly indicated, and the morphological features were represented by clusters of extracted cells. A comparison with the morphological feature extraction method based on curvature thresholds proved the proposed method's robustness to DEM noise. When verified against a landslide inventory, the morphological features of almost all recent (<5years) landslides and approximately 35% of historical (>10years) landslides were extracted. This finding indicates that the proposed method can facilitate landslide detection, although the cell clusters extracted from curvature images should be filtered using a filtering strategy based on supplementary information provided by expert knowledge or other data sources.