3D Motion Manipulation for Micro- and Nanomachines: Progress and Future Directions.

In the past decade, micro- and nanomachines (MNMs) have made outstanding achievements in the fields of targeted drug delivery, tumor therapy, microsurgery, biological detection, and environmental monitoring and remediation. Researchers have made significant efforts to accelerate the rapid development of MNMs capable of moving through fluids by means of different energy sources (chemical reactions, ultrasound, light, electricity, magnetism, heat, or their combinations). However, the motion of MNMs is primarily investigated in confined two-dimensional (2D) horizontal setups. Furthermore, three-dimensional (3D) motion control remains challenging, especially for vertical movement and control, significantly limiting its potential applications in cargo transportation, environmental remediation, and biotherapy. Hence, an urgent need is to develop MNMs that can overcome self-gravity and controllably move in 3D spaces. This review delves into the latest progress made in MNMs with 3D motion capabilities under different manipulation approaches, discusses the underlying motion mechanisms, explores potential design concepts inspired by nature for controllable 3D motion in MNMs, and presents the available 3D observation and tracking systems.

Automatic z-Axis Correction for IR-MALDESI Mass Spectrometry Imaging of Uneven Surfaces.

Two-dimensional mass spectrometry imaging (2D MSI) experiments mainly involve samples with a flat surface and constant thickness, but some samples are challenging to section due to the texture and topography. Herein, we present an MSI method that automatically corrects for discernible height differences across surfaces during imaging experiments. A chromatic confocal sensor was incorporated into the infrared matrix-assisted laser desorption electrospray ionization (IR-MALDESI) system to measure the sample surface height at the location of each analytical scan. The height profile is subsequently used for adjusting the z-axis position of the sample during MSI data acquisition. We evaluated this method using a tilted mouse liver section and an unsectioned Prilosec tablet due to their exterior quasi-homogeneity and height differences of approximately ∼250 µm. MSI with automatic z-axis correction showed consistent ablated spot sizes and shapes, revealing the measured ion spatial distribution across a mouse liver section and a Prilosec tablet. Conversely, irregular spots and reduced signals with large variability were observed when no z-axis correction was applied.

MR microneurography of human peripheral fascicles using a clinical 3T MR scanner.

BACKGROUND AND PURPOSE: Knowledge of nerve fascicular structures is essential for managing peripheral nerve disorders. This study aimed to investigate the feasibility of z-axis high-resolution magnetic resonance (MR) microneurography (zH-MRMN) in displaying the three-dimensional structures of tibial nerve fascicles in vivo using a 3T MR scanner. MATERIALS AND METHODS: Twelve volunteers underwent z-axis conventional-resolution MR microneurography (zC-MRMN) and zH-MRMN of tibial nerves. The visibility scores of the nerve fascicles (VSNFs) on axial zC-MRMN images and axial zH-MRMN multiplanar reformation (MPR) images were compared. The nerve fascicle appearances on the longitudinal zH-MRMN MPR images were described. RESULTS: In the nerve segments whose long axes were perpendicular to the imaging planes of both zC-MRMN and zH-MRMN, the VSNFs were not significantly different between the axial images of the two modalities (P = 0.083). In the nerve segments whose long axes were not perpendicular to the imaging planes of zC-MRMN, the VSNFs on the axial zC-MRMN images were significantly lower than those on the axial zH-MRMN MPR images that were angled perpendicular to the long axis of the tibial nerve (P < 0.001). CONCLUSIONS: The longitudinal zH-MRMN MPR images clearly displayed the changing features of the intraneural fascicles as well as the gross morphology of the tibial nerves. zH-MRMN can clearly delineate the topography of the tibial nerve fascicles in vivo through use of a 3T MR scanner.

[A Study of Longitudinal NPS Measurement in CT Images Based on the Central Cross-section Theorem].

PURPOSE: Various approaches in noise power spectrum (NPS) analysis are currently used for measuring a patient's longitudinal (z-direction) NPS from three-dimensional (3D) CT volume data. The purpose of this study was to clarify the relationship between those NPSs and 3D-NPS based on the central slice theorem. METHODS: We defined the 3D-NPS(fx, fy, fz) that was calculated by 3D Fourier transform (FT) from 3D noise data (3D-Noise(x, y, z), x-y scan plane). Here, fx, fy and fz are spatial frequencies corresponding to the axes of x, y and z, respectively. Based on the central slice theorem, we described three relationships as follows. (1) The fz-directional NPS calculated from the 3D-Noise(x=0, y=0, z) is equal to the profile obtained by projecting 3D-NPS(fx, fy, fz) in fx- and fy-directions. (2) The fz-directional NPS calculated from the profile obtained by projecting 3D-Noise(x=0, y, z) in the y-direction is equal to the profile at fy=0 in the data obtained by projecting 3D-NPS(fx, fy, fz) in the fx-direction. (3) The fz-directional NPS calculated from the profile obtained by projecting 3D-Noise(x, y, z) in x and y-directions is equal to the profile of 3D-NPS(fx=0, fy=0, fz). To verify them, we compared the NPSs measured from actual 3D noise data that were obtained using a cylindrical water phantom. RESULTS: In each relationship (1)-(3), the fz-directional NPS matched the profile obtained from the 3D-NPS(fx, fy, fz). CONCLUSION: Based on the central slice theorem, we clarified the relationships between fz-directional NPSs and 3D-NPS. We should understand them and then consider which method should be used for fz-directional NPS measurement.

Development of Deep Learning-based Automatic Scan Range Setting Model for Lung Cancer Screening Low-dose CT Imaging.

RATIONALE AND OBJECTIVES: To develop an automatic setting of a deep learning-based system for detecting low-dose computed tomography (CT) lung cancer screening scan range and compare its efficiency with the radiographer's performance. MATERIALS AND METHODS: This retrospective study was performed using 1984 lung cancer screening low-dose CT scans obtained between November 2019 and May 2020. Among 1984 CT scans, 600 CT scans were considered suitable for an observational study to explore the relationship between the scout landmarks and the actual lung boundaries. Further, 1144 CT scans data set was used for the development of a deep learning-based algorithm. This data set was split into an 8:2 ratio divided into a training set (80%, n = 915) and a validation set (20%, n = 229). The performance of the deep learning algorithm was evaluated in the test set (n = 240) using actual lung boundaries and radiographers' scan ranges. RESULTS: The mean differences between the upper and lower boundaries of the deep learning-based algorithm and the actual lung boundaries were 4.72 ± 3.15 mm and 16.50 ± 14.06 mm, respectively. The accuracy and over-scanning of the scan ranges generated by the system were 97.08% (233/240) and 0% (0/240) for the upper boundary, and 96.25% (231/240) and 29.58% (71/240) for the lower boundary. CONCLUSION: The developed deep learning-based algorithm system can effectively predict lung cancer screening low-dose CT scan range with high accuracy using only the frontal scout.

Variability of redundant scan coverages along the Z-axis and dose implications for common computed tomography examinations.

BACKGROUND: Scan length optimization is a method of optimization which ensures that, imaging is performed to cover just the area of interest without unnecessarily exposing structures that would not add value to answer a given clinical question. PURPOSE: This study assessed the variability and degree of redundant scan coverages along the z-axis of CT examinations of common indications and the associated radiation dose implications in CT facilities in Ghana for optimization measures to be recommended. METHODS: On reconstructed acquired CT images, the study measured extra distances covered above and below anatomical targets for common indications with calibrated calipers across 25 CT facilities. The National Cancer Institute Dosimetry System for CT (NCICT) (Monte Carlo-based-software) was used to simulate the scanning situations and organ dose implications for scans with and without the inclusion of the redundant scan areas. RESULTS: A total of 1,640 patients' CT data sets were used in this study. The results demonstrated that CT imaging utilized varying scan lengths (16.45±21.0-45.99±4.3 cm), and 70.6% of the scans exceeded their pre-defined anatomic boundaries by a mean range of 2.86±1.07-5.81±1.66 cm, thereby resulting in extra patient radiation dose. Hence, scanning without the redundant coverages could generate a dose length product (DLP) reduction of 17.5%, 18.8%, 15.5% and 9.0% without degrading image quality for brain lesion, lung lesion, pulmonary embolism and abdominopelvic lesion CT imaging, respectively, whilst ensuring organ dose reduction of0.8%-79.1%. CONCLUSION: The study strongly recommends that radiographers should avoid the inclusion of redundant areas in CT examinations to reduce organ doses.

Adaptive statistical iterative reconstruction for computed tomography of the spine.

INTRODUCTION: The utility of evaluating a sagittal view of CT of the spine is well-known. In many clinical cases, the sagittal view includes noise generated from surrounding objects and may degrade the image quality. Iterative reconstruction (IR) techniques are useful for noise reduction; however, they can reduce spatial resolution. The aim of this study was to evaluate the effectiveness of the adaptive statistical iterative reconstruction (ASiR) for generating sagittal CT images of the spine when compared to filtered back projection (FBP). METHODS: The image quality of clinical images from 25 patients were subjectively assessed. Three radiologists rated spatial resolution, image noise, and overall image quality using a five-point scale. For objective assessment, z-direction modulation transfer function (z-MTF) was measured using a custom-made phantom. Additionally, z-axis noise power spectrum (z-NPS) was measured using a water phantom. An improved adaptive statistical iterative reconstruction algorithm called ASiR-V was used in this study. Blending levels were 50%, and 100% (ASiR-V50, ASiR-V100, respectively). RESULTS: For subjective assessments, images using ASiR-V100 were determined to have the best overall image quality, despite having received the worst score in the assessment of spatial resolution. For objective assessments, the image using ASiR-V50 and ASiR-V100 curves were slightly degraded in terms of low contrast z-MTF when compared to FBP. CONCLUSION: ASiR-V was effective to improve the image quality when compared with FBP when reviewing sagittal reformats of the spine. IMPLICATIONS FOR PRACTICE: This study suggests that high resolution is not the only thing that is key when reviewing sagittal CT spinal reformats. Such images should be provided as part of routine CT spine protocols, where available.

A Resonant Z-Axis Aluminum Nitride Thin-Film Piezoelectric MEMS Accelerometer.

In this paper, we report a novel aluminum nitride (AlN) thin-film piezoelectric resonant accelerometer. Different from the ordinary MEMS (micro-electro-mechanical systems) resonant accelerometers, the entire structure of the accelerometer, including the mass and the springs, is excited to resonate in-plane, and the resonance frequency is sensitive to the out-plane acceleration. The structure is centrosymmetrical with serpentine electrodes laid on supporting beams for driving and sensing. The stiffness of the supporting beams changes when an out-plane inertial force is applied on the structure. Therefore, the resonance frequency of the accelerometer will also change under the inertial force. The working principle is analyzed and the properties are simulated in the paper. The proposed AlN accelerometer is fabricated by the MEMS technology, and the structure is released by an ICP isotropic etching. The resonance frequency is 24.66 kHz at a static state. The quality factor is 1868. The relative sensitivity of this accelerometer, defined as the shift in the resonance frequency per gravity unit (1 g = 9.8 m/s2) is 346 ppm/g. The linearity of the accelerometer is 0.9988. The temperature coefficient of frequency (TCF) of this accelerometer is -2.628 Hz/°C (i.e., -106 ppm/°C), tested from -40 °C to 85 °C.

Abdominal-pelvic scanning parameters revisited: a case for Z-axis reduction in patients with clinical suspicion for acute appendicitis.

PURPOSE: The purpose of this study was to determine if CT for appendicitis can be abbreviated to begin at the top of the L2 vertebral body level and still maintain the detection rate of appendicitis and other symptomatic pathology without omitting significant incidental findings. METHODS: Retrospective review of CT abdomen-pelvis exams for suspected appendicitis over a 5-month period was performed. The Z-axis scan length of the original full scans and theoretical limited scans from the top of L2 were recorded and calculated. Images were reviewed for incidental findings above the L2 vertebral body level and categorized by severity per American College of Radiology (ACR) white paper guidelines. Final diagnoses based on imaging findings were also recorded. RESULTS: One hundred nineteen patients (46 males, 73 females, mean age 29 ± 14) were included. Appendicitis was present in 26 cases (22%). Using a theoretical scan beginning at the top of the L2 vertebral body, none of the findings leading to diagnosis of appendicitis would have been missed. A total of 30 incidental findings were found above the L2 vertebral body. Per ACR white paper guidelines, 26 of these findings did not require additional imaging follow-up. Additional follow-up imaging was recommended for 3 of the findings above L2, and 1 right adrenal metastasis was found above L2 in a patient with previously undiagnosed NSCLC. This patient coincidentally also had appendicitis. No symptomatic pathology would have been missed had the scans begun at the top of the L2 vertebral body. Such an abbreviated scan would have resulted in a mean Z-axis reduction of 12.9 cm (30.3%). CONCLUSIONS: CT using abbreviated Z-axis scan length can reduce radiation dose and provide necessary imaging needed to diagnose appendicitis or other symptomatic pathology without omitting significant incidental findings.

Thick methacrylate sections devoid of lost caps simplify stereological quantifications based on the optical fractionator design.

In neuroscience, the optical fractionator technique is frequently used for unbiased cell number estimations. Although unbiased in theory, the practical application of the technique is often biased by the necessity of introducing a guard zone at one side of the disector to counter lost caps and/or optical limitations. Restricting the disector within the section thickness potentially introduces bias in two ways. First, the need to measure section thickness in order to obtain the disector height/section thickness fraction is challenging since both microcator measurements, microtome block advance, and measurements on re-embedded sections are potentially biased. Second, disector placement is not uniform random within the section thickness resulting in a bias in most sections with inhomogeneous cell distribution along the z axis. Re-embedded 2-hydroxyethylmethacrylate (hereafter methacrylate) sections were inspected for lost caps to evaluate the possibility of whole section thickness counting with the optical fractionator technique and hippocampal granular cell nucleoli density differences along the z axis were assessed with a z axis analysis. No lost caps were found in the examined re-embedded tissue and an inhomogeneous cell distribution through the section thickness was observed. In thick methacrylate sections devoid of lost caps sampling through the entire section thickness could be an acceptable alternative to the use of guard zones and the consequent biases associated with section thickness measurement and non-random placement of disectors.

Parameter estimation and interval type-2 fuzzy sliding mode control of a z-axis MEMS gyroscope.

This paper reports a hybrid intelligent controller for application in single axis MEMS vibratory gyroscopes. First, unknown parameters of a micro gyroscope including unknown time varying angular velocity are estimated online via normalized continuous time least mean squares algorithm. Then, an additional interval type-2 fuzzy sliding mode control is incorporated in order to match the resonant frequencies and to compensate for undesired mechanical couplings. The main advantage of this control strategy is its robustness to parameters uncertainty, external disturbance and measurement noise. Consistent estimation of parameters is guaranteed and stability of the closed-loop system is proved via the Lyapunov stability theorem. Finally, numerical simulation is done in order to validate the effectiveness of the proposed method, both for a constant and time-varying angular rate.

Optimal z-axis scanning parameters for gynecologic cytology specimens.

BACKGROUND: The use of virtual microscopy (VM) in clinical cytology has been limited due to the inability to focus through three dimensional (3D) cell clusters with a single focal plane (2D images). Limited information exists regarding the optimal scanning parameters for 3D scanning. AIMS: The purpose of this study was to determine the optimal number of the focal plane levels and the optimal scanning interval to digitize gynecological (GYN) specimens prepared on SurePath™ glass slides while maintaining a manageable file size. SUBJECTS AND METHODS: The iScanCoreo Au scanner (Ventana, AZ, USA) was used to digitize 192 SurePath™ glass slides at three focal plane levels at 1 µ interval. The digitized virtual images (VI) were annotated using BioImagene's Image Viewer. Five participants interpreted the VI and recorded the focal plane level at which they felt confident and later interpreted the corresponding glass slide specimens using light microscopy (LM). The participants completed a survey about their experiences. Inter-rater agreement and concordance between the VI and the glass slide specimens were evaluated. RESULTS: This study determined an overall high intra-rater diagnostic concordance between glass and VI (89-97%), however, the inter-rater agreement for all cases was higher for LM (94%) compared with VM (82%). Survey results indicate participants found low grade dysplasia and koilocytes easy to diagnose using three focal plane levels, the image enhancement tool was useful and focusing through the cells helped with interpretation; however, the participants found VI with hyperchromatic crowded groups challenging to interpret. Participants reported they prefer using LM over VM. This study supports using three focal plane levels and 1 µ interval to expand the use of VM in GYN cytology. CONCLUSION: Future improvements in technology and appropriate training should make this format a more preferable and practical option in clinical cytology.

Disector Z-axis mechanical method for stereology

The purpose of this work is to calibrate a not expensive microscope to be applied in Optical Disector estimation. The evaluation of "Z-axis" bias and the "Z-axis" calibration were made utilizing a cover slip and a "manual digimatic outside micrometer scale" (Mitutoyo, Japan). Calibrating the cover slip we performed the calibration of the "Z-axis" of a microscope. In the cover slip two lines were painted with different colors using a pen glass. A blue line was painted on the up surface and another line (red) on the bottom surface of the cover slip forming a cross. Two metal rings with one palette welded in each were adapted in the microscope. Other palette was welded in the gross focuses in order to restrict the route of the fine focuses (Z-axis study) using the two palettes fixed in both rings. Results show that 10 micrometers in "Z-axis" were equal to 3.2 micrometers in the scale of its fine focuses of the microscope. Then, a Disector of 10μm (10μm in Z-axis) is equal to 3.2 micrometers in the fine focuses of this microscope. In conclusion, "Z-axis" calibration is crucial to assure enough precision for Disector Method since the equipment can be manufactured without the ideal precision or its precision can be lost after use.

O propósito deste trabalho é a Calibração de um microscópio comum de baixo custo de forma a usá-lo para estimativas do Método Disector Óptico. A avaliação do viés e a calibração do "eixo-Z" foram feitas usando uma lamínula e um "micrômetro manual digital" (Mitutoyo, Japan). Com a cali-bração da lamínula, calibramos o "eixo-Z" de um microscópio. Foram pintadas duas linhas com diferentes cores utilizando canetas para vidro. Uma linha (azul) foi pintada na superfície superior da lamínula e outra linha (vermelha) foi pintada na superfície inferior da lamínula, formando uma cruz. Dois anéis de metal com uma paleta de metal soldada a cada um deles foram adaptados ao micrométrico do microscópio. Outra paleta foi soldada ao macrométrico do mesmo microscópio, o que foi feito de forma a limitar o percurso do micrométrico (eixo-Z) pela ação desta em conjunto com a ação das duas paletas fixadas no micrométrico. Os resultados mostraram que 10 micrômetros no "eixo-Z" do microscópio foi igual a 3,2 na escala do seu micrométrico. Assim, um Disector de 10μm (10μm no eixo-Z) é igual a 3,2 micrômetros no micrométrico do microscópio utilizado. Concluindo, a calibração do eixo-Z é crucial para assegurar a precisão suficiente para as avaliações usando o Método Disector, já que os equipamentos podem ser manufaturados sem a precisão ideal ou podem perder sua precisão durante o tempo com o uso.

Discussion on Automated Dose Management / 医疗卫生装备

The method and developing progress on CT automated dose management are introduced. Modern method on CT automated dose management compromises real-time angular dose modulation and Z axis tube current modulation. Provided the automated dose management are correctly applied,the image quality can be optimized at minimum dose.

A Frequency Weighting Contour for Chinese Young Males / 航天医学与医学工程

Objective To obtain the frequency weighting contour for seated Chinese young males in z axis.Method 10 male volunteers served as the subjects.They were exposed to standard vibration stimulus (a sinusoidal vibration of 1.0 m/s2 at 8 Hz) and 14 kinds of sinusoidal experimental vibration stimuli at frequencies from 4 Hz to 80 Hz.The magnitude of the experimental vibration stimulus was changed by the subject through a signal condition and switching device made by ourselves to obtain an equal vibration sensation to the standard vibration.The data were fitted to the same form of the frequency weighting Wk of ISO 2631-1 with the least square method and optimization of parameters.Result Compared with ISO 2631-1,the frequencies weightings of Chinese young males at 16～80 Hz are significantly higher than those of ISO 2631-1(P<0.005),but there are no significant difference between two frequency weighting contours at other frequencies. Conclusion Chinese young males are more sensitive to vibration at 16～80 Hz in Z axis.