Translational Axes Research Articles

Transitions and oscillatory regimes in two-layer geostrophic hetons and tripoles

We investigate numerically the transitions and oscillatory regimes in two-layer quasigeostrophic hetons and tripoles composed of patches of uniform potential vorticity (PV). The contour-surgery algorithms are employed, in which either some symmetries are preserved, or asymmetric evolution of the vortex structures is allowed, induced by generally asymmetric numerical noise. The fluid layers are assumed equally thick. First, the evolution of hetons is considered. A heton, a steadily translating pair of vortices residing in different layers, is antisymmetric in the sense that the two PV patches are opposite in sign and symmetric in shape about the axis of translation. A feebly stable heton, when exposed to weak antisymmetric perturbations, responds by developing an oscillation, which culminates in a transition to a new, substantially robust oscillating heton. The results obtained reinforce our earlier findings regarding the modon-to-modon transition (Kizner et al., J. Fluid Mech., vol. 468, 2002, pp. 239–270; Kizner, Phys. Fluids, vol. 18 (5), 2006, 056601; Kizner, UTAM Symposium on Hamiltonian Dynamics, Vortex Structures, Turbulence (ed. Borisov et al.), IUTAM Bookseries, vol. 6, 2008, pp. 125–133. Springer) and clarify the transition mechanism. Asymmetric perturbations might cause a heton-to-tripole transition. Next we consider the transitions and oscillations in carousel tripoles exposed to weak, generally asymmetric perturbations. A carousel tripole is a steadily rotating centrally symmetric ensemble of three PV patches, with the central vortex being located in one layer and the two remaining, satellite vortices in the other layer. Depending on the tripoles’ size, hence also on the shape of the satellite vortices, three different types of transition are revealed, the transition to a ringed (shielded) monopole being one of them. Whereas the transition of a ringed monopole into a tripole is a known phenomenon, the reverse transition in baroclinic flows is detected for the first time.

Hierarchical imaging: a new concept for targeted imaging of large volumes from cells to tissues.

BackgroundImaging large volumes such as entire cells or small model organisms at nanoscale resolution seemed an unrealistic, rather tedious task so far. Now, technical advances have lead to several electron microscopy (EM) large volume imaging techniques. One is array tomography, where ribbons of ultrathin serial sections are deposited on solid substrates like silicon wafers or glass coverslips.ResultsTo ensure reliable retrieval of multiple ribbons from the boat of a diamond knife we introduce a substrate holder with 7 axes of translation or rotation specifically designed for that purpose. With this device we are able to deposit hundreds of sections in an ordered way in an area of 22 × 22 mm, the size of a coverslip. Imaging such arrays in a standard wide field fluorescence microscope produces reconstructions with 200 nm lateral resolution and 100 nm (the section thickness) resolution in z.By hierarchical imaging cascades in the scanning electron microscope (SEM), using a new software platform, we can address volumes from single cells to complete organs. In our first example, a cell population isolated from zebrafish spleen, we characterize different cell types according to their organelle inventory by segmenting 3D reconstructions of complete cells imaged with nanoscale resolution. In addition, by screening large numbers of cells at decreased resolution we can define the percentage at which different cell types are present in our preparation. With the second example, the root tip of cress, we illustrate how combining information from intermediate resolution data with high resolution data from selected regions of interest can drastically reduce the amount of data that has to be recorded. By imaging only the interesting parts of a sample considerably less data need to be stored, handled and eventually analysed.ConclusionsOur custom-designed substrate holder allows reproducible generation of section libraries, which can then be imaged in a hierarchical way. We demonstrate, that EM volume data at different levels of resolution can yield comprehensive information, including statistics, morphology and organization of cells and tissue. We predict, that hierarchical imaging will be a first step in tackling the big data issue inevitably connected with volume EM.Electronic supplementary materialThe online version of this article (doi:10.1186/s12860-016-0122-8) contains supplementary material, which is available to authorized users.

Generalized cutting loads decomposition model of five-axis serial machine tools based on the screw theory

There are large volume of existing literatures focused on cutting force modeling, but so far only few research has been reported on cutting loads decomposition model to calculate cutting loads components acted on five axes of the machine, which, however, directly affect five-axis tracking accuracy. To this end, a generalized cutting loads decomposition model of five-axis serial machine tools is proposed, which provides a mathematical basis to evaluate the cutting loads components. A cutting loads decomposition model is first developed based on kinematics and virtual work analysis, then a generalized cutting loads decomposition model is established by differentiating the forward kinematics model based on the screw theory. Kinematic factors that affect the cutting load components on translational and rotary axes are also analyzed, which provides a guidance to optimize the workpiece setup location to reduce the cutting loads components acted on rotary axes. Experiments and simulations on a table-tilting five-axis machine tool verify the effectiveness of the proposed model.

Local Corner Smoothing Transition Algorithm Based on Double Cubic NURBS for Five-axis Linear Tool Path

A five-axis tool path is often composed of a linear path that has a tangential discontinuity so that the tangential velocity will be abrupt or be equal to zero at the corner of the adjacent segments. Therefore, it greatly affects the machining efficiency and quality. Thus, a corner smoothing transition algorithm based on double cubic NURBS, which is curvature-continuous and satisfies the given accuracy constraint, is proposed to smooth the local corner at the adjacent five-axis linear path. On the basis of the smoothing transition model, the parametric synchronization between the smoothed double NURBS trajectories and the remaining two linear segments are respectively constructed to realize the smoothing variation along the tool tip translational trajectory and tool axis rotational trajectory. The simulation and examples show that the proposed transition algorithm can satisfy the error constraints, reduce the feedrate fluctuation, and improve the machining quality.

Measurement Parameters Optimized for Sequential Multilateration in Calibrating a Machine Tool with a DOE Method

Improving volumetric error compensation is one of the machine tool user’s key objectives. Smart compensation is bound to calibration accuracy. Calibration quality depends largely on its setup factors. An evaluation criterion is thus required to test the quality of the compensation deduced from these setup factors. The residual error map, which characterizes post-compensation machine errors, is therefore chosen and then needs to be evaluated. In this study, the translation axes of a machine tool were calibrated with a multilateration tracking laser interferometer. In order to optimize such measurements, the residual error map was then characterized by two appliances: a laser interferometer and the tracking laser already employed for the calibration, using for that purpose the sequential multilateration technique. This research work thus aimed to obtain a smart setup of parameters of machine tool calibration analyzing these two residual error maps through the Design Of Experiment (DOE) method. To achieve this goal, the first step was to define the setup parameters for calibrating a compact machine tool with a multilateration tracking laser. The second step was to define both of the measurement processes that are employed to estimate the residual error map. The third step was to obtain the optimized setup parameters using the DOE method.

Hysteresis soil-water characteristic curves of highly expansive clay

The main objective of this study is to evaluate the hysteresis of soil–water characteristic curves (SWCC) of highly expansive clay subjected to wetting and drying cycles. Variables considered included hysteresis suction range (i.e. low and high suction ranges), suction determination technique (vapour equilibrium technique, axis translation technique and contact filter paper technique) and initial specimen condition. Experimental results revealed that the degree of SWCC hysteresis was higher in the low hysteresis suction range (less than 1.5 MPa) than the high hysteresis suction range (greater than 1.5 MPa). The results further revealed notable difference between matric and total SWCCs of this expansive clay. Furthermore, a hysteresis was observed that is inherent to suction determination technique and is independent of soil characteristics. Also, it was concluded that initial specimen condition (i.e. as-compacted and saturated) had a significant impact on degree of hysteresis, especially in the low suction range. Plausible explanations of observed trends in view of soil–water retention mechanism were provided. Finally, volumetric strains during drying and wetting paths were evaluated and its impact on SWCC was assessed.

Interfractional setup corrections using Hexapod robotic couch for VMAT head and neck treatments

Introduction Inaccurate alignment of the radiation beam with the patient can lead to critical organs to receive an unwanted high dose or the tumor to receive a reduced dose producing a loss in tumor control. Purpose To establish the interfractional setup error, for VMAT head and neck patients, using a kilovoltage cone beam CT (CBCT) and a robotic treatment couch (Hexapod) for accurate patient positioning in six degrees of freedom. Materials and methods A total of 315 fractions from 10 H&N patients were evaluated. The Hexapod corrected the misalignments and a pre-treatment CBCT verification was obtained. For each patient the daily variations of the three principal axes (X, Y and Z) and three rotational movements (pitch, roll, and yaw) were extracted. The following parameters were calculated: the mean of the setup corrections (M), the standard deviation (random error) and the standard deviation of all the means measured for each patient (systematic error). Results The overall mean displacements are (0.0, −0.5, 0.3) mm for the translations and (0.60, −0.45, −0.11) degrees for the rotations. The random errors are (2.2, 2.3, 2.6) mm and (1.29, 1.35, 1.28) degrees. The systematic errors are (1.7, 1.6, 2.0) mm and (0.86, 1.01, 0.98) degrees. Conclusion The M values were equal or less than 0.5 mm for the translational axes. We obtained relatively larger random errors than systematic errors in both translational and rotational movements. This result agrees with the literature for head and neck displacements. Disclosure None declared.

Squareness error modeling for multi-axis machine tools via synthesizing the motion of the axes

This paper presents one novel model of squareness errors using the D-H matrix to improve the accuracy of integrated geometric errors of the machine tools. It considers the motion of the axis and reflects the geometric meaning of the squareness errors. Firstly, analysis of the existing squareness error models is proposed. It helps to find the improvements of the modeling. Secondly, squareness error modeling is represented by integrating the kinematic property of the axes. The influences of squareness errors are to change the translational direction of translational axes and to deflect the axial line of rotary axes. The squareness error model of translational axes is expressed as the translational homogeneous matrix along the real movement direction. And, the model of rotary axes is expressed as the rotational homogeneous matrix around the real axial line. The unit vector of the real direction is established based on the geometric definition of squareness errors. The models are available for different axes with the property of the axes. Finally, experiments are conducted on one SmartCNC500 five-axis machine tool. The virtual large squareness errors of translational axes and C-axis are simulated by the motion of axes. The positions of the target are measured by laser tracker when moving the axes. The comparisons of measured points and calculated points with the proposed model and one existing model are proposed. The results show that the novel models are precise.

Calibrated Linear Array-Driven Photoacoustic/Ultrasound Tomography

The anisotropic resolution of linear arrays, tools that are widely used in diagnostics, can be overcome by compounding approaches. We investigated the ability of a recently developed calibration and a novel algorithm to determine the actual radial transducer array distance and its misalignment (tilt) with respect to the center of rotation in a 2-D and 3-D tomographic setup. By increasing the time-of-flight accuracy, we force in-phase summation during the reconstruction. Our setup is composed of a linear transducer and a rotation and translation axis enabling multidimensional imaging in ultrasound and photoacoustic mode. Our approach is validated on phantoms and young mice ex vivo. The results indicate that application of the proposed analytical calibration algorithms prevents image artifacts. The spatial resolution achieved was 160 and 250 μm in photoacoustic mode of 2-D and 3-D tomography, respectively.

The tool following function-based identification approach for all geometric errors of rotary axes using ballbar

This paper proposes a tool following function-based identification approach (TFFIA) for geometric errors of two rotary axes for one five-axis machine tool. It is comprehensive to identify all geometric errors of rotary errors. Firstly, synthetic error formulas of ballbar originate from the geometric error model of machine tools in order to consider the influences of 21 errors of three translational axes. It makes the approach more reasonable and precise. Secondly, the structures of three measurement patterns of TFFIA are described. Thirdly, in each pattern, errors of rotary axes affecting the accuracy of the sensitive direction are identified. As the result, the identification equations of all 20 errors coincide with the geometric properties of errors. Moreover, the impacts of setup errors of ballbar are eliminated with least square method to improve the precise of TFFIA. According to the structures of three patterns, only three installation of workpiece ball of ballbar are needed in the whole identification of two rotary axes to obtain the required ballbar readings. It greatly shortens the measurement time. Twenty geometric errors of two rotary axes are calculated with identification equations and ballbar readings. Finally, TFFIA is applied to a SmartCNC500 five-axis vertical machining center. The corresponding comparisons are proposed to verify the effectiveness and accuracy of TFFIA.

Water retention and volumetric characteristics of intact and re-compacted loess

A laboratory testing program was conducted to investigate the effects of microstructure on the water retention curve (WRC) and wetting–drying induced volume change in loess. The axis translation and vapor equilibrium techniques were adopted to control suction in the range of 0–400 kPa and 4–140 MPa, respectively. Hysteresis in the WRC of loess was observed for the entire range of suction studied. Compared to re-compacted loess, intact loess exhibits a more pronounced hysteresis in the suction range below 20 kPa, which can be explained by the ink-bottle pore neck effect or constricted pores. The hypothesis is supported by microstructural evidence of mercury intrusion porosimetry and scanning electron microscopy tests. However, re-compacted loess exhibits larger hysteresis than intact loess for suctions above 30 kPa. A conceptual model was introduced, which links WRC to the corresponding pore-size density (PSD) function. Regarding volume change, more noticeable drying-induced shrinkage, but yielding at a lower suction, was observed for re-compacted loess. This is consistent with the compression test results. Stress has a significant effect on change of PSD and constricted macropores leading to a shift in the main wetting curve and a less pronounced hysteresis. Intact loess exhibits a stress-dependent wetting-induced collapse and drying-induced shrinkage.

The Water Retention Characteristics of an Unsaturated Compacted Loess Material

The water retention curve of an unsaturated compacted loess material has been obtained by combining the filter paper method, the vapour equilibrium method and the axis translation method. It was indicated that the combined method is efficient to investigate the water retention characteristics of compacted loess materials. The results showed that the osmotic suction in the compacted loess varies slightly with the increasing water content. Higher matric suction occurs in the compacted loess compared with the natural loess at the same moisture.

Effectiveness of Selective Thoracic Fusion in the Surgical Treatment of Syringomyelia-associated Scoliosis: A Case-control Study With Long-term Follow-up.

A retrospective case-control studyOBJECTIVE.: The aim of the study was to investigate the effectiveness of selective thoracic fusion in the surgical treatment of patients with syringomyelia-associated scoliosis. Selective thoracic fusion technique was introduced to treat idiopathic scoliosis patients with major thoracic curve. Theoretically, such therapeutic philosophy could be applied to syringomyelia patients. There is no previous study that specifically addresses the effectiveness of selective thoracic fusion in patients with syringomyelia-associated scoliosis. Two groups of scoliosis patients were enrolled, including 52 patients with syringomyelia-associated scoliosis and 52 patients with adolescent idiopathic scoliosis. Selective thoracic fusion was performed for both groups. Radiographic parameters including Cobb angle, apical vertebral translation, trunk shift, thoracic kyphosis (TK), lumbar lordosis, and sagittal vertical axis were measured on the standing posteroanterior and lateral radiographs before surgery, 1 week postoperatively and at the final follow-up, respectively. Inter- and intragroup comparisons were performed for each variable. Patients of the two groups were matched in terms of age, sex, fusion levels, duration of follow-up, and all preoperative radiographic parameters except for TK. At the final follow-up, the coronal correction of the thoracic curve was comparable between the two groups (58.8 ± 10.2% vs. 61.3 ± 8.7%, P = 0.25). Moreover, the two groups were observed to have a similar improvement of lumbar curve (62.4 ± 7.3% vs. 64.9 ± 6.9%, P = 0.33). The mean correction loss of thoracic curve and lumbar curve in syringomyelia group were 3.6 ± 3.2% and 5.3 ± 1.8% respectively, showing no statistical difference when compared with those of adolescent idiopathic scoliosis group. The sagittal spinal alignments of the two groups, including TK and lumbar lordosis, were similarly maintained during the follow-up. Syringomyelia-associated scoliosis can be successfully corrected through selective thoracic fusion surgery with a promising long-term surgical outcome. 3.

SU‐G‐JeP4‐04: Commissioning and Acceptance Testing of Optical Surface Monitoring System On TrueBEAM STx as Per Task Group 147

Purpose:Optical Surface Monitoring system (OSMS) have been recently introduced by Varian for initial patient positioning and real‐time monitoring during complex radiotherapy treatment. The purpose of this work was to implement TG 147 with OSMS.Methods:Recently we installed OSMS first of its kind in India on trueBEAM STx at our Institue. The OSMS is composed of a three cameras ceiling mounted and a Workstation. The following tests were performed to validate the system a. Calibration b. System reproducibility and drift c. Static localization displacement accuracy and d. Dynamic radiation gating delivery. The Calibration procedure consists of Daily,Monthly and MV Radiation Isocenter Calibration. The reproducibility of system was tested by monitoring the varian gating phantom test pattern for at least 120 min. Each recorded pattern was registered to the reference surface to calculate the required couch adjustment. To measure the static localization displacement accuracy of the system to detect and quantify patient shift relative to a reference image,we compared the shift detected by the surface imaging system with known couch transitions in a phantom study. The phantom was set in a motion and the radiation beam was holded by changing the threshold in the software for different clinical setups to test the dynamic radiation gating capability.Results:Daily calibration was within ±0.5 mm. The MV radiation isocentre with respect to cameras was less than 1 mm in translational axis and less than 0.5° for rotational axis. The reproducibility was found to be 0.4 mm. The maximum static displacement accuracy was 0.75 mm for the three translational axis, and less than 0.5° for rotational axis. The system was able to hold the beam with a minimum threshold of 1 mm.Conclusion:A quality assurance process has been developed as per TG 147 for the clinical implementation of an OSMS in radiation therapy.

TH-AB-202-12: The First Clinical Implementation of a Real-Time Six Degree of Freedom Tracking System During Radiation Therapy

Purpose: In current practice, imaging is typically performed prior to treatment; the cancer target motion during treatment is unknown. We present the first clinical implementation of real time Kilovoltage Intrafraction Monitoring (KIM) system which tracks the cancer target translational and rotational motions during treatment. Methods: KIM technology: KIM estimates the 3D position of the target tumour based on segmented 2D positions of the three implanted fiducials in each of the kV images (125 kV, 10 mA at 11 fps) taken continuously during the treatment arc. The 2D-3D target estimation is based on a probability distribution function, obtained during pre-treatment CBCT. Rotations about each axis with the centroid of the markers as the pivot were calculated using the iterative closest point algorithm in real time. Patient: A patient with prostate adenocarcinoma undergoing stereotactic body radiotherapy (SBRT) with 36.25 Gy delivered in 5 fractions (Varian TrueBeam, 6X, VMAT) was enrolled in the study. The trial complies with Australian ethical and regulatory standards. Results: Of the 5 fractions of treatment the patient received, KIM was utilised successfully in 4 fractions with 3 couch shifts due to large persistent prostate movements (>2mm for more than 5 seconds). KIM translational accuracy and precision in comparison with post treatment kV-MV triangulation are 0.28±0.59 mm, −0.19±0.25 mm and 0.23±0.69 mm in the Left-Right, Superior-Inferior and Anterior-Posterior directions, respectively. KIM rotational accuracy as compared with triangulation is: 0.429°±2.22°, −0.44°±4.7° and 0.06°±1.08° in the roll, pitch and yaw direction, respectively. Conclusion: The first six degree of freedom KIM system was successfully implemented clinically. The presented KIM system has sub-millimeters accuracy and precision in all three translational axes, and less than 1° of mean error in all three rotational axes. Acknowledgement: This work is supported by Cancer Australia grants APPXXX, APPYYY.

SU‐F‐T‐466: An Enhanced Daily Quality Assurance Process for a Six Degrees of Freedom Robotic Table

Purpose:A Varian PerfectPitch six degrees of freedom robotic table necessitates daily quality assurance (QA). Therapists were credentialed for this QA procedure which was easily incorporated into the existing daily warmup process. This procedure adds depth to TG‐142 requirements without additional morning time costs.Methods:This PerfectPitch table QA introduces a consistent rotation of the QUASAR™ Penta‐Guide phantom and requires automatic table corrections through image fusions. Rotational offsets are generated by inserting a platform tool under a specified corner of the phantom; then a conebeamCT is performed. This conebeamCT image is fused with a planned reference CT image set and the table is auto‐adjusted to correct for induced translational and rotational offsets. After executing table shifts, a second conebeamCT verifies the table movement and the phantom's return to isocenter.Results:Pre‐shift and post‐shift table corrections were recorded daily. It was discovered that due to slight variations in the setup, it took three performances of the QA for each therapist to have consistent induced rotations. Four therapists performed this QA and after the initial training period, the inter‐user variability was minimal. Consistency of the induced rotation was evaluated by the variation of the pre‐shift table corrections. Excluding the first three attempts of each therapist, the pre‐shift table correction standard deviations were ≤ 0.67mm for the translational axes and ≤ 0.49° for the rotational axes. Accuracy of the automatic table movement was confirmed by the post‐shift table corrections. The average post‐shift table corrections for the translational axes were ≤ 0.15mm and for the rotational axes were ≤ 0.42°. Using our clinic's existing table corrections tolerance of <1mm and <0.5°, these results were deemed acceptable.Conclusion:Therapists successfully and rapidly adopted daily QA procedures using the PerfectPitch table; automated rotational robotic table motions were confirmed through image fusions. This procedure enhances existing TG‐142 recommendations.

Development of a Passive Compliant Mechanism for Measurement of Micro/Nanoscale Planar 3-DOF Motions

This paper presents the design, optimization, and computational and experimental performance evaluations of a passively actuated, monolithic, compliant mechanism. The mechanism is designed to be mounted on or built into any precision positioning stage, which produces three degree-of-freedom (3-DOF) planar motions. It transforms such movements into linear motions, which can then be measured using laser interferometry-based sensing and measurement techniques commonly used for translational axes. This methodology reduces the introduction of geometric errors into sensor measurements, and bypasses the need for increased complexity sensing systems. A computational technique is employed to optimize the mechanism's performance, in particular, to ensure the kinematic relationships match a set of desired relationships. Computational analysis is then employed to predict the performance of the mechanism throughout the workspace of a coupled positioning stage, and the errors are shown to vary linearly with the input position. This allows the errors to be corrected through calibration. A prototype is manufactured and experimentally tested, confirming the ability of the proposed mechanism to permit measurements of 3-DOF motions.

An investigation on modeling and compensation of synthetic geometric errors on large machine tools based on moving least squares method

This article intends to provide an efficient modeling and compensation method for the synthetic geometric errors of large machine tools. Analytical and experimental examinations were carried out on a large gantry-type machine tool to study the spatial geometric error distribution within the machine workspace. The result shows that the position accuracy of the tool-tip is affected by all the translational axes synchronously, and the position error curve shape is non-linear and irregular. Moreover, the angular error combined with Abbe’s offset during the motion of a translational axis would cause Abbe’s error and generate significant influence on the spatial positioning accuracy. In order to identify the combined effect of the individual error component on the tool-tip position accuracy, a synthetic geometric error model is established for the gantry-type machine tool. Also, an automatic modeling algorithm is proposed to approximate the geometric error parameters based on moving least squares in combination with Chebyshev polynomials, and it could approximate the irregular geometric error curves with high-order continuity and consistency with a low-order basis function. Then, to implement real-time error compensation on large machine tools, an intelligent compensation system is developed based on the fast Ethernet data interaction technique and external machine origin shift, and experiment validations on the gantry-type machine tool showed that the position accuracy could be improved by 90% and the machining precision could be improved by 85% after error compensation.

Machine Bed Support with Sliding Surface for Improving the Motion Accuracy

The purpose of this study is to develop a new machine bed support mechanism for reducing the vibration generated during the high-speed tracking motion of numerical control machine tools. In order to achieve this, the frequency response and motion trajectory of a machine tool with the proposed machine bed, which has a sliding surface, are measured and compared with that of the conventional support. Based on the modal analysis of the machine tool structure, a mathematical model representing the influence of the machine bed characteristics on the vibration is also developed. The model consists of a bed, saddle, table, column, and spindle head. Every component has three degrees of freedom for each of the translational and rotational axes. In order to evaluate the characteristics of the machine bed, the mathematical model determines the stiffness and damping along the X-, Y-, and Z-axis between the bed and the ground. The frequency response curves simulated by using the mathematical model are compared with that of the measured ones. From the results of the experiments and simulations, it is confirmed that the vibration generated during high-speed tracking motions can be reduced by using the proposed machine bed with a sliding surface.

Feasibility of patient dose reduction based on various noise suppression filters for cone-beam computed tomography in an image-guided patient positioning system

We investigated the feasibility of patient dose reduction based on six noise suppression filters for cone-beam computed tomography (CBCT) in an image-guided patient positioning (IGPP) system. A midpoint dose was employed as a patient dose index. First, a reference dose (RD) and low-dose (LD)-CBCT images were acquired with a reference dose and various low doses. Second, an automated rigid registration was performed for three axis translations to estimate patient setup errors between a planning CT image and the LD-CBCT images processed by six noise suppression filters (averaging filter, median filter, Gaussian filter, edge-preserving smoothing filter, bilateral filter, and adaptive partial median filter (AMF)). Third, residual errors representing the patient positioning accuracy were calculated as Euclidean distances between the setup error vectors estimated using the LD-CBCT and RD-CBCT images. Finally, the residual errors as a function of the patient dose index were estimated for LD-CBCT images processed by six noise suppression filters, and then the patient dose indices for the filtered LD-CBCT images were obtained at the same residual error as the RD-CBCT image. This approach was applied to an anthropomorphic phantom and four cancer patients. The patient dose for the LD-CBCT images was reduced to 19% of that for the RD-CBCT image for the phantom by using AMF, while keeping a same residual error of 0.47 mm as the RD-CBCT image by applying the noise suppression filters to the LD-CBCT images. The average patient dose was reduced to 31.1% for prostate cancer patients, and it was reduced to 82.5% for a lung cancer patient by applying the AMF. These preliminary results suggested that the proposed approach based on noise suppression filters could decrease the patient dose in IGPP systems.