Alignment Verification Research Articles

Research on preparation of micron-scale orthogonally aligned HMS patterns based on soft lithography

The soft lithography enables the fabrication of microfluidic honeycombs, which are micron-scale, orthogonally aligned hexagonal mesoporous silica (HMS) patterns with channels embedded within them, on silicon substrates. The process entails meticulous cleaning, precise master mold design (including features for channel alignment) using electron-beam lithography, generation of polydimethylsiloxane (PDMS) mold creation, ink formulation, and pattern transfer. Subsequent steps include the sol-gel transition, hardening, alignment verification, characterization, and optional functionalization. It is of the utmost importance to optimize these steps and the master design in order to achieve success. Therefore, the paper examines the creation of micron-scale HMS patterns with orthogonal alignment through the innovative application of soft lithography. The technique encompasses the strategic design of hexagonal motifs, precision master mold crafting, the PDMS stamps, and a meticulous sol-gel procedure, resulting in HMS structures that exhibit remarkable precision and adaptability. This paper underscores the transformative potential of soft lithography in the realm of advanced materials, which offers a controlled and uniform approach to size and uniformity. The refined soft lithography process not only achieves the precise orthogonal alignment of HMS patterns but also highlights its adaptability and economic viability in nanotechnology ventures.

A Review Study of Differences Between Alignment Verification Standards

A Review Study of Differences Between Alignment Verification Standards

Re] Value Alignment Verification

Re] Value Alignment Verification

650 GHz imaging as alignment verification for millimeter wave corneal reflectometry.

A system concept for online alignment verification of millimeter-wave, corneal reflectometry is presented. The system utilizes beam scanning to generate magnitude-only reflectivity maps of the cornea at 650 GHz and compares these images to a precomputed/measured template map to confirm/reject sufficient alignment. A system utilizing 5 off-axis parabolic mirrors, a thin film beam splitter, and 2-axis galvanometric mirror was designed, simulated, and evaluated with geometric and physical optics. Simulation results informed the construction of a demonstrator system which was tested with a reference reflector. Similarity metrics computed with the aligned template and 26 misaligned positions, distributed on a 0.5 mm x 0.5 mm x 0.5 mm mesh, demonstrated sufficient misalignment detection sensitivity in 23 out of 26 positions. The results show that positional accuracy on the order of 0.5 mm is possible using 0.462 mm wavelength radiation due to the perturbation of coupling efficiency via beam distortion and beam walk-off.

Misalignment algorithm of a wide-field survey telescope based on third-order quadratic nodal aberration theory

Off-axis three-mirror anastigmatic (TMA) telescopes with designed decenters and tilts, have many misalignment degrees of freedom and strong coupling between each misalignment degree of freedom. Therefore, it is difficult to establish misalignment equations only using A222 and A131 in nodal aberration theory (NAT). In addition, for off-axis TMA optical systems with designed decenters and tilts, the robustness of the existing fifth-order NAT misalignment calculation algorithm based on high-order Zernike coefficients and boresight errors decreases, so it is difficult to realize its engineering application. To solve the issue of insufficient practicality of the existing misalignment algorithm based on fifth-order NAT, a third-order NAT calculation algorithm based on quadratic aberration field decenter vectors is derived and established. Two concepts of inherent aberration field decenter vector and misalignment aberration field decenter vector are proposed. Taking an off-axis TMA optical system with 6-m focal length as the research object, simulations, and alignment verification experiments were carried out. Compared with the existing fifth-order NAT misalignment algorithm, the results show that when measurement noise is not considered, the two methods can both obtain convergent calculation results, and the average RMS wavefront errors (WFE) of the optical system are both corrected to be below 0.0574 waves. When different levels of measurement noise are introduced, the robustness of the fifth-order NAT misalignment algorithm decreases, and there are even cases where the optical system completely fails to be corrected. However, the algorithm based on quadratic aberration field decenter vectors shows better robustness. Under different levels of measurement noise, this algorithm could correct the average RMS WFE of the optical system to around 0.0574 waves.

Alignment Verification and Monitoring Strategies for the Sirius Light Source

Alignment Verification and Monitoring Strategies for the Sirius Light Source

On the MLC leaves alignment in the direction orthogonal to movement.

The main focus of the recommended spatial accuracy tests for the multi‐leaf collimators (MLC) is calibration of the leaf position along the movement direction and overall alignment to the radiation isocenter. No explicit attention was typically paid to the alignment of the leaves from the opposing banks in the direction orthogonal to movement. This paper is a case study demonstrating that verification of such alignment at the time of acceptance testing is prudent. The original standard MLC (SMLC) on an MRIdian MRI‐guided linac (ViewRay Inc., Mountain View, CA, USA) was upgraded to a high‐speed MLC (HSMLC), which is supposed to be mechanically identical to the SMLC except for the higher drive screw pitch. The results of the end‐to‐end IMRT tests demonstrated unacceptable dosimetric results exemplified by an average and maximum ion chamber (IC) point dose error in the high‐dose low‐gradient region of 2.5 ± 1.4% and 4.6%, respectively. Before the upgrade, those values were 0.3 ± 0.7% and 0.9%, respectively. An exhaustive analysis of possible failure modes eventually zeroed in on the average misalignment of about 1 mm in the Y (along the couch) direction between the right and left upper MLC banks. The MLC was replaced, reducing the Y‐direction misalignment to 0.4 mm. As a result, the average and maximum IC dose‐errors became acceptable 1.0 ± 0.7% and 1.6%, respectively. Simple film and/or chamber array tests during acceptance testing can easily detect Y‐direction misalignments between opposing leaves banks measuring a fraction of a mm at isocenter. Left undetected, such misalignment can cause nontrivial dosimetric consequences.

Methodology for performing biomechanical push-out tests for evaluating the osseointegration of calvarial defect repair in small animal models

Push-out tests are frequently used to evaluate the bone-implant interfacial strength of orthopedic implants, particularly dental and craniomaxillofacial applications. There currently is no standard method for performing push-out tests on calvarial models, leading to a variety of inconsistent approaches. In this study, fixtures and methods were developed to perform push-out tests in accordance with the following design objectives: (i) the system rigidly fixes the explanted calvarial sample, (ii) it minimizes lateral bending, (iii) it positions the defect accurately, and (iv) it permits verification of the coaxial alignment of the defect with the push-out rod. The fixture and method was first validated by completing push-out experiments on 30 explanted murine cranial caps and two explanted leporine cranial caps, all induced with bilateral sub-critical defects (5.0 mm and 8.0 mm nominal diameter for the murine and leporine models, respectively). Defects were treated with an autograft (i.e., excised tissue flap), a shape memory polymer (SMP) scaffold, or a PEEK implant. Additional validation was performed on 24 murine cranial caps induced with a single, unilateral critically-sized defect (8.0 mm nominal diameter) and treated with an autograft or a SMP scaffold.•A novel fixture was developed for performing push-out mechanical tests to characterize the strength of a bone-implant interface in calvarial defect repair.•The fixture uses a 3D printed vertical clamp with mating alignment component to fix the sample in place without inducing lateral bending and verify coaxial alignment of push-out rod with the defect.•The fixture can be scaled to different calvarial defect geometries as validated with 5.0 mm bilateral and 8.0 mm single diameter murine calvarial defect model and 8.0 mm bilateral leporine calvarial defect model.

Study on alignment test based on ASTM E1012 and Chinese guideline

This paper describes the study about alignment test on testing machine. It is based on the standards of ASTM E1012-14 (Standard Practice for Verification of Testing Frame and Specimen Alignment Under Tensile and Compressive Axial Force Application) and Chinese calibration guideline. The strain-gauge specimens of ASTM and reference extensometer of Chinese guideline were both tested on one testing machine. The test results were analyzed and compared. The traceability about both methods were also discussed. Meanwhile the amplifier was calibrated before test. It is the first time in China to performance this comparison test.

Prosthetic Accuracy Depends on the Design of Patient-Specific Instrumentation: Results of a Retrospective Study Using Three-Dimensional Imaging.

To determine accuracy of patient-specific instrumentation (PSI), the preoperative three-dimensional (3D) plan should be superimposed on the postoperative 3D image to compare prosthetic alignment. We aimed to compare prosthetic alignment on a preoperative 3D computed tomography (CT) plan and postoperative 3D-CT image, and evaluate the accuracy of PSI during total knee arthroplasty (TKA). Thirty consecutive knees (30 patients) who underwent TKA using PSI were retrospectively evaluated. The preoperative plan was prepared using 3D CT acquisitions of the hip, knee, and ankle joints. The postoperative 3D CT image obtained 1 week after surgery was superimposed onto the preoperative 3D plan using computer software. Differences in prosthetic alignment between the preoperative and postoperative images were measured using six parameters: coronal, sagittal, and axial alignments of femoral and tibial prostheses. Differences in prosthetic alignment greater than 3 degrees were considered outliers. Two observers performed all measurements. All parameters were repeatedly measured over a 4-week interval. This measurement method's intraobserver and interobserver reliabilities were more than 0.81 (very good). For the femoral and tibial prostheses, absolute differences between the preoperative and postoperative 3D CT images were significantly larger in the sagittal than in the coronal and axial planes (p < 0.001). The outlier rate for the sagittal alignment of femoral and tibial prostheses was significantly higher than that for the alignment of coronal and axial planes (p < 0.001). However, there were no significant differences in the range of motion (ROM) before and after TKA when comparing cases with and without outliers in the sagittal plane. Even though the present study did not reveal any issues with the ROM that depended on the presence of an outlier, accurate verification of prosthetic alignment for individual PSI models may be necessary because the designs, referenced images, and accuracy are different in each model.

Toward Anomaly Behavior Detection as an Edge Network Service Using a Dual-Task Interactive Guided Neural Network

How to use artificial intelligence technology to mine human abnormal behavior from considerable video data generated by the Internet-of-Things system has been intensively studied for a long time. Existing deep learning anomaly detection algorithms deployed in the cloud typically perform supervised learning based on constant kinds of abnormal behavior data. However, this supervised learning model with preset abnormal behavior categories ignores the diversity and unpredictability of abnormal occurrences in open scenarios. Thus, we propose an abnormal behavior detection algorithm as an edge network service by combining the advantages of cloud computing and the efficiency of edge networks. This method combines the double verification of global behavior detection and local fine-grained action cycle alignment to detect whether a behavior is abnormal. Moreover, to enable abnormal behavior detection models to predict test samples whose categories do not appear during the training stage, we propose an active label learning algorithm based on cycle clustering, which not only improves the efficiency of data transmission between the edge and the cloud but also makes model updates in the cloud more efficient. Extensive and quantitative experimental results show that our method can not only accurately detect abnormal human behavior at the edge of limited resources but also has strong robustness under the interference of test samples of unknown categories.

Quality assurance of test blueprinting.

Tests offer scores that measure student learning and programs outcomes. Valid examinations are needed to accurately reflect scores related to dimensions of knowledge, analysis and different competencies in health education. The primary step in the process of exam development should be the construction of a test blueprint. The degree of alignment of a test with its blueprint is a critical element of content validity. However, the availability of a published blueprint does not ensure that instructors adhere to it when developing their tests. This article aims to present a tool for quantitative determination of the degree of consistency between the actual test and the developed blueprint. Ensuring the quality of the test blueprinting process, through objective verification of alignment of the test with the test blueprint, increases the extent of content validity of students' assessments.

Accuracy of low-dose proton CT image registration for pretreatment alignment verification in reference to planning proton CT.

PurposeProton CT (pCT) has the ability to reduce inherent uncertainties in proton treatment by directly measuring the relative proton stopping power with respect to water, thereby avoiding the uncertain conversion of X‐ray CT Hounsfield unit to relative stopping power and the deleterious effect of X‐ ray CT artifacts. The purpose of this work was to further evaluate the potential of pCT for pretreatment positioning using experimental pCT data of a head phantom.MethodsThe performance of a 3D image registration algorithm was tested with pCT reconstructions of a pediatric head phantom. A planning pCT simulation scan of the phantom was obtained with 200 MeV protons and reconstructed with a 3D filtered back projection (FBP) algorithm followed by iterative reconstruction and a representative pretreatment pCT scan was reconstructed with FBP only to save reconstruction time. The pretreatment pCT scan was rigidly transformed by prescribing random errors with six degrees of freedom or deformed by the deformation field derived from a head and neck cancer patient to the pretreatment pCT reconstruction, respectively. After applying the rigid or deformable image registration algorithm to retrieve the original pCT image before transformation, the accuracy of the registration was assessed. To simulate very low‐dose imaging for patient setup, the proton CT images were reconstructed with 100%, 50%, 25%, and 12.5% of the total number of histories of the original planning pCT simulation scan, respectively.ResultsThe residual errors in image registration were lower than 1 mm and 1° of magnitude regardless of the anatomic directions and imaging dose. The mean residual errors ranges found for rigid image registration were from −0.29 ± 0.09 to 0.51 ± 0.50 mm for translations and from −0.05 ± 0.13 to 0.08 ± 0.08 degrees for rotations. The percentages of sub‐millimetric errors found, for deformable image registration, were between 63.5% and 100%.ConclusionThis experimental head phantom study demonstrated the potential of low‐dose pCT imaging for 3D image registration. Further work is needed to confirm the value pCT for pretreatment image‐guided proton therapy.

A new method for the calibration of strain cylinders using laser interferometry

This research investigates the possibility of calibrating strain cylinders using laser interferometry, thus providing a new type of transducer that can provide both force and deformation indications. This new method for the calibration of strain cylinders is based on the application of a dual channel laser interferometer in a force standard machine. Using the proposed new method, the relationship between force, deformation, and strain can be calibrated in parallel when calibration forces are applied according to the procedure outlined in ISO 376. Experimental results show that the deformation of a strain cylinder has a definite and stable relationship with the force applied and can be calibrated and directly traced to the wavelength of the laser. Therefore, a new standard that can be used for both alignment verification and indication verification of compression testing machines and other uniaxial testing machines is proven. The research also illustrates the possibility of providing a new deformation-type force transducer using a non-gauged steel cylinder together with a multi-channel laser interferometer.

PO-0992: Electron IORT in vivo film dosimetry in breast cancer for alignment and dose verification

PO-0992: Electron IORT in vivo film dosimetry in breast cancer for alignment and dose verification

Image Reconstruction with a Fast, Monolithic Proton Radiography System

Proton radiography enables proton range verification in addition to the anatomical alignment verification currently obtained with x-ray radiography. Design specifications require that a clinical system be simple, lightweight, easily scaled to large field sizes, operate at high speed to maximize patient throughput, and expose the patient to the minimum possible radiation dose for a given resolution. We are developing a system to produce images of proton stopping power by tracking individual protons proximal and distal to the patient and then measuring the proton residual range after traversing the patient. Due to multiple scattering effects, each proton deviates randomly from its projected trajectory. To achieve optimal spatial resolution, an image reconstruction algorithm must fully exploit the individual three-dimensional proton position information. We have developed an iterative algorithm for radiography that fully exploits proton path information to produce projective radiographs with no blurring from multiple scattering. Simulations of our detector design, with and without multiple scattering effects included, determine the expected accuracy of our proton path reconstruction, and the impact on the spatial resolution of the reconstructed image. Tests of our detector components with proton beams demonstrate the performance needed to validate our simulations. Protons typically scatter transversely from the projected path by 4 mm after 20 cm of water. Our simulations demonstrate path reconstruction of individual protons to better than 1 mm. Our iterative algorithm successfully produces images with 1 mm sharpness. The iterative process necessarily increases pixel noise compared to estimates neglecting multiple scattering and additional protons will be needed to achieve a given contrast. Operation of our detector components in a test beam demonstrates the required proton tracking resolution and efficiency to optimize resolution and minimize dose to the patient. A proton radiography system optimizing image sharpness and dose to the patient will individually track protons before and after the patient. An iterative algorithm produces images with spatial resolution given by the tracking accuracy, at the price of increased pixel noise. We are in the process of integrating the necessary components into a fully functional system.

High Precision Low Temperature Direct Wafer Bonding Technology for Wafer-Level 3D ICs Manufacturing

The increased microelectronic devices complexity is raising a strong demand for high wafer-to-wafer (w2w) alignment accuracy allowing for high levels of integration by wafers stacking. One of the major aspects for the alignment is the overlay alignment accuracy as this is strongly impacting on the final yield: the future generation devices will require w2w overlay alignment accuracies in the range of 100 nm or lower. The overlay alignment accuracy can be split into following errors: translation, rotation, run-out and distortion of the patterns on the wafers. In order to meet the increasing demand of overlay alignment accuracy, all those components have to be considered for optimization in the alignment technology development.This work presents different newly developed concepts for high precision aligned w2w bonding processes which are applicable for any low temperature fusion bonding or Cu/dielectric hybrid bonding processes. The new technologies enable sub-100 nm w2w overlay alignment accuracy. The components of w2w overlay accuracy and the latest developments for their optimization are introduced and different approaches of run-out compensation with and without temperature compensation are introduced. Finally, a feedback loop between SmartView®NT2 w2w alignment system with integrated run-out compensation and in-situ post bond alignment verification module (AVM) will be shown. Additionally to the w2w alignment process and the feedback-loop which is monitoring and controlling the overlay accuracy, a new technique will be presented, which allows a fully automated in-situ recycling method of bonded wafers, which are out of alignment-specification.The process development was performed using a Gemini®FB-XT fully automated wafer bonding system, equipped with a plasma activation chamber enabling low temperature bonding processes, a SmartView®NT2 optical aligner using a face-to-face alignment principle, a pre-bonding station used for bringing the substrates in contact after alignment, an alignment verification module (AVM) as well as a debonding module which allows for re-working of the wafer pairs failing the alignment criteria.For optimization of the overlay accuracy on bonded wafers, the optimization steps have to address the individual components of the overlay. A significant contributor to the overlay accuracy is the scaling or run-out error, so the main focus of this evaluation is the run-out compensation process in SmartView®NT2. A well-known run-out compensation method in lithography is a thermal compensation of the scaling, which can also be applied for bonding.Deeper investigations showed that the thermal run-out compensation has major disadvantages in terms of wafer-stress and pattern distortion, which are significant problems for BSI CIS, so this type of compensation would not be an acceptable general solution for such stress- and overlay alignment-sensitive applications.Multiple new methods for run-out compensation without using thermal compensation were successfully developed, enabling w2w overlay accuracy better than 100 nm on every point measured on the wafers stack and overlay accuracy values better than 100 nm could already be shown successfully.

SU-G-BRB-09: Kompeito-Shot: Development of a Novel Verification System for 3D Beam Alignment Including the Sag of Gantry Head

Purpose: High accuracy of beam axis is required for high-precision radiation therapy. It is impossible to quantitatively and directly evaluate the sagging effect of the gantry head using current methods (star-shot and Winston-Lutz tests) when the gantry head sags under the weight of MLC and X-Y jaws. We introduce a novel method “Kompeito-shot (3D star-shot)” for the verification of 3D beam alignment (3D isocentricity). This method enables direct measurement of the sagging effect. We developed the system and examined the concept of this system. Methods: The system composed of a plastic scintillator (PS), a truncated cone-shaped mirror, a plane mirror and a CCD camera. Two types of PS were compared. One consisted of a column PS (Co system), the other consisted of a column PS inserted into a barrel PS with shading film in between (Co-Ba system). The system was irradiated with a 6-MV photon beam and the scintillation light was measured using the CCD camera through the mirror system. The gantry angle was set from 270 to 300 degrees to mimic the sagging of the gantry head for evaluating the accuracy of the system. The distance between a center of PS and entrance / exit points were calculated to analyze the gantry angle. And, the calculated gantry angle and the irradiated gantry angle were compared. Results: We compared the measured image of Co system and that of Co-Ba system. Entrance and exit areas were visualized clearly. The histogram showing the difference between the calculated gantry angle and the irradiated gantry angle was fitted with a Gaussian function. Mean and standard deviation of Co-Ba system were smaller than that of Co system by one order of magnitude. Conclusion: We developed the Kompeito-shot system and evaluated the accuracy of the system. The basic concept works for the verification of 3D isocentricity.

WE‐EF‐303‐10: Single‐ Detector Proton Radiography as a Portal Imaging Equivalent for Proton Therapy

Purpose:In proton therapy, patient alignment is of critical importance due to the sensitivity of the proton range to tissue heterogeneities. Traditionally proton radiography is used for verification of the water‐equivalent path length (WEPL), which dictates the depth protons reach. In this work we propose its use for alignment. Additionally, many new proton centers have cone‐beam computed tomography in place of beamline X‐ray imaging and so proton radiography offers a unique patient alignment verification similar to portal imaging in photon therapy.Method:Proton radiographs of a CIRS head phantom were acquired using the Beam Imaging System (BIS) (IBA, Louvain‐la‐Neuve) in a horizontal beamline. A scattered beam was produced using a small, dedicated, range modulator (RM) wheel fabricated out of aluminum. The RM wheel was rotated slowly (20 sec/rev) using a stepper motor to compensate for the frame rate of the BIS (120 ms). Dose rate functions (DRFs) over two RM wheel rotations were acquired. Calibration was made with known thicknesses of homogeneous solid water. For each pixel the time width, skewness and kurtosis of the DRFs were computed. The time width was used to compute the object WEPL. In the heterogeneous phantom, the excess skewness and excess kurtosis (i.e. difference from homogeneous cases) were computed and assessed for suitability for patient set up.Results:The technique allowed for the simultaneous production of images that can be used for WEPL verification, showing few internal details, and excess skewness and kurtosis images that can be used for soft tissue alignment. These latter images highlight areas where range mixing has occurred, correlating with phantom heterogeneities.Conclusion:The excess skewness and kurtosis images contain details that are not visible in the WET images. These images, unique to the time‐resolved proton radiographic method, could be used for patient set up according to soft tissues.

Towards online patient imaging during helical radiotherapy.

Exit-detector data from helical radiation therapy have been studied extensively for delivery verification and dose reconstruction. Since the same radiation source is used for both imaging and treatment, this work investigates the possibility of utilising exit-detector raw data for imaging purposes. This gives rise to potential clinical applications such as retrospective daily setup verification and inter-fractional setup error detection. The exit-detector raw data were acquired and independently analysed using Python programming language. The raw data were extracted from the treatment machine's onboard computer, and converted into 2D array files. The contours of objects (phantom or patient) were acquired by applying a logarithmic function to the ratio of two sinograms, one with the object in the beam and one without. The setup variation between any two treatment deliveries can be detected by applying the same function to their corresponding exit-detector sinograms. The contour of the object was well defined by the secondary radiation from the treatment beam and validated with the imaging beam, although no internal structures were discernible due to the interference from the primary radiation. The sensitivity of the setup variation detection was down to 2 mm, which was mainly limited by the resolution of the exit-detector itself. The exit-detector data from treatment procedures contain valuable photon exit fluence maps which can be utilised for contour definition and verification of patient alignment without reconstruction.