CT Imaging System Research Articles

Setup errors analysis in iterative kV CBCT: A clinical study of cervical cancer treated with Volumetric Modulated Arc Therapy.

This study aims to analyze setup errors in pelvic Volumetric Modulated Arc Therapy (VMAT) for patients with non-surgical primary cervical cancer, utilizing the onboard iterative kV cone beam CT (iCBCT) imaging system on the Varian Halcyon 2.0 ring gantry structure accelerator to enhance radiotherapy precision. We selected 132 cervical cancer patients who underwent VMAT with daily iCBCT imaging guidance. Before each treatment session, a registration method based on the bony structure was employed to acquire iCBCT images with the corresponding planning CT images. Following verification and adjustment of image registration results along the three axes (but not rotational), setup errors in the lateral (X-axis), longitudinal (Y-axis), and vertical (Z-axis) directions were recorded for each patient. Subsequently, we analyzed 3642 iCBCT image setup errors. The mean setup errors for the X, Y, and Z axes were 4.50±3.79mm, 6.08±6.30mm, and 1.48±2.23mm, respectively. Before correction with iCBCT, setup margins based on the Van Herk formula for the X, Y, and Z axes were 6.28, 12.52, and 3.26mm, respectively. In individuals aged 60 years and older, setup errors in the X and Y axes were significantly larger than those in the younger group (p<0.05). Additionally, there is no significant linear correlation between setup errors and treatment fraction numbers. Data analysis underscores the importance of precise Y-axis setup for cervical cancer patients undergoing VMAT. Radiotherapy centers without daily iCBCT should appropriately extend the planning target volume (PTV) along the Y-axis for cervical cancer patients receiving pelvic VMAT. Elderly patients exhibit significantly larger setup errors compared to younger counterparts. In conclusion, iCBCT-guided radiotherapy is recommended for cervical cancer patients undergoing VMAT to improve setup precision.

Development of a proton CT imaging system using scintillator-based range detection.

The accuracy of proton therapy and preclinical proton irradiation experiments is susceptible to proton range uncertainties, which partly stem from the inaccurate conversion between CT numbers and relative stopping power (RSP). Proton computed tomography (PCT) can reduce these uncertainties by directly acquiring RSP maps. This study aims to develop a novel PCT imaging system based on scintillator-based proton range detection for accurate RSP reconstruction. The proposed PCT system consists of a pencil-beam brass collimator with a 1mm aperture, an object stage capable of translation and 360° rotation, a plastic scintillator for dose-to-light conversion, and a complementary metal oxide semiconductor (CMOS) camera for light distribution acquisition. A calibration procedure based on Monte Carlo (MC) simulation was implemented to convert the obtained light ranges into water equivalent ranges. The water equivalent path lengths (WEPLs) of the imaged object were determined by calculating the differences in proton ranges obtained with and without the object in the beam path. To validate the WEPL calculation, measurements of WEPLs for eight tissue-equivalent inserts were conducted. PCT imaging was performed on a custom-designed phantom and a mouse, utilizing both 60 and 360 projections. The filtered back projection (FBP) algorithm was employed to reconstruct the RSP from WEPLs. Image quality was assessed based on the reconstructed RSP maps and compared to reference and simulation-based reconstructions. The differences between the calibrated and reference ranges of 110-150 MeV proton beams were within 0.18mm. The WEPLs of eight tissue-equivalent inserts were measured with accuracies better than 1%. Phantom experiments exhibited good agreement with reference and simulation-based reconstructions, demonstrating average RSP errors of 1.26%, 1.38%, and 0.38% for images reconstructed with 60 projections, 60 projections after penalized weighted least-squares algorithm denoising, and 360 projections, respectively. Mouse experiments provided clear observations of mouse contours and major tissue types. MC simulation estimated an imaging dose of 3.44 cGy for decent RSP reconstruction. The proposed PCT imaging system enables RSP map acquisition with high accuracy and has the potential to improve dose calculation accuracy in proton therapy and preclinical proton irradiation experiments.

Implications of coronary calcification on the assessment of plaque pathology: a comparison of computed tomography and multimodality intravascular imaging.

This study aimed to investigate the impact of calcific (Ca) on the efficacy of coronary computed coronary angiography (CTA) in evaluating plaque burden (PB) and composition with near-infrared spectroscopy-intravascular ultrasound (NIRS-IVUS) serving as the reference standard. Sixty-four patients (186 vessels) were recruited and underwent CTA and 3-vessel NIRS-IVUS imaging (NCT03556644). Expert analysts matched and annotated NIRS-IVUS and CTA frames, identifying lumen and vessel wall borders. Tissue distribution was estimated using NIRS chemograms and the arc of Ca on IVUS, while in CTA Hounsfield unit cut-offs were utilized to establish plaque composition. Plaque distribution plots were compared at segment-, lesion-, and cross-sectional-levels. Segment- and lesion-level analysis showed no effect of Ca on the correlation of NIRS-IVUS and CTA estimations. However, at the cross-sectional level, Ca influenced the agreement between NIRS-IVUS and CTA for the lipid and Ca components (p-heterogeneity < 0.001). Proportional odds model analysis revealed that Ca had an impact on the per cent atheroma volume quantification on CTA compared to NIRS-IVUS at the segment level (p-interaction < 0.001). At lesion level, Ca affected differences between the modalities for maximum PB, remodelling index, and Ca burden (p-interaction < 0.001, 0.029, and 0.002, respectively). Cross-sectional-level modelling demonstrated Ca's effect on differences between modalities for all studied variables (p-interaction ≤ 0.002). Ca burden influences agreement between NIRS-IVUS and CTA at the cross-sectional level and causes discrepancies between the predictions for per cent atheroma volume at the segment level and maximum PB, remodelling index, and Ca burden at lesion-level analysis. Coronary calcification affects the quantification of lumen and plaque dimensions and the characterization of plaque composition coronary CTA. This should be considered in the analysis and interpretation of CTAs performed in patients with extensive Ca burden. Coronary CT Angiography is limited in assessing coronary plaques by resolution and blooming artefacts. Agreement between dual-source CT angiography and NIRS-IVUS is affected by a Ca burden for the per cent atheroma volume. Advanced CT imaging systems that eliminate blooming artefacts enable more accurate quantification of coronary artery disease and characterisation of plaque morphology.

Cone-beam CT with a noncircular (sine-on-sphere) orbit: imaging performance of a clinical system for image-guided interventions.

We aim to compare the imaging performance of a cone-beam CT (CBCT) imaging system with noncircular scan protocols (sine-on-sphere) to a conventional circular orbit. A biplane C-arm system (ARTIS Icono; Siemens Healthineers) capable of circular and noncircular CBCT acquisition was used, with the latter orbit (sine-on-sphere, "Sine Spin") executing a sinusoidal motion with tilt amplitude over the half-scan orbit. A test phantom was used for the characterization of image uniformity, noise, noise-power spectrum (NPS), spatial resolution [modulation transfer function (MTF) in axial and oblique directions], and cone-beam artifacts. Findings were interpreted using an anthropomorphic head phantom with respect to pertinent tasks in skull base neurosurgery. The noncircular scan protocol exhibited several advantages associated with improved 3D sampling-evident in the NPS as filling of the null cone about the spatial frequency axis and reduction of cone-beam artifacts. The region of support at the longitudinal extrema was reduced from 16 to at a radial distance of 6.5cm. Circular and noncircular orbits exhibited nearly identical image uniformity and quantum noise, demonstrating cupping of and overall noise of . Although both the radially averaged axial MTF ( ) and 45deg oblique MTF ( ) were lower for the noncircular orbit compared with the circular orbit at the default full reconstruction field of view (FOV), there was no difference in spatial resolution for the medium reconstruction FOV (smaller voxel size). Differences in the perceptual image quality for the anthropomorphic phantom reinforced the objective, quantitative findings, including reduced beam-hardening and cone-beam artifacts about structures of interest in the skull base. Image quality differences between circular and noncircular CBCT orbits were quantitatively evaluated on a clinical system in the context of neurosurgery. The primary performance advantage for the noncircular orbit was the improved sampling and elimination of cone-beam artifacts.

MiRNA signature related to atherosclerotic lesion induced shear stress modifications in familial hypercholesterolemia patients with subclinical atherosclerosis: a bioinformatics systems biology study

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Institute of Health Carlos III (ISCIII) Background Patients with familial hypercholesterolemia (FH), even when appropriately treated, are at risk of premature clinical atherosclerotic cardiovascular disease (ASCVD) presentation. Although atherosclerosis (AT) is directly related to hemodynamic disturbances affecting the vascular geometry, there is scarce information on whether there is miRNA-mediated/flow-mediated modulation of atherosclerosis in FH. Purpose To identify a differential plasma miRNA signature related to fluid shear stress (FSS) in well controlled FH-patients with asymptomatic atherosclerosis. Methods FH-patients (N=49) with subclinical atherosclerosis, identified by computed tomographic angiography, and a reference cohort of non-FH subjects (N=32), both from a national FH-Registry, were included in the study. Coronary plaque volume and phenotype was analyzed by means of the QAngio CT imaging system. miRNAs associated to FSS were defined in silico by bioinformatics (KEGG, Cytoscape, GTEX portal, miRWalk, miRBase tools) and validated in plasma samples by RT-qPCR using TaqMan technology. Results By in silico analysis, 7 miRNAs targeting genes involved in features of functions (ROS production, oxidative stress, leukocyte transendothelial/migration-inflammation and vasodilation) of shear stress-induced cellular dysfunction and atherosclerosis (KEGG, hsa05418) were identified by miRWalk and miRBase databases. Of the 7 miRNAs, a 6-miRNA signature showed significantly lower plasma levels in FH-patients than in the non-FH group (P&amp;lt;0.01 for: miR-30e-5p, miR-378a-3p, let-7d-3p, and miR-550-5p; P=0.03 for miR-324-3p). In the FH-group, miR-324-3p, miR-30e-5p, miR-378a-3p and let-7d-3p significantly discriminated patients stratified by the plaque volume of non-calcified lesions (fibro-lipidic phenotype), using the median plaque volume as cut-off value. And even further, a high percentage (65-70%) of FH-subjects with low levels of the 4 miRNA had plaque volumes above the median. Interestingly, this miRNA-signature did not differentiate FH-patients stratified by the volume of calcified plaques. Conclusion FH-patients show a significantly lower content of an atherosclerosis/shear stress signature of 4 miRNAs targeting genes involved in subclinical atherosclerosis progression in FH.

A level-set method with the 3D multiplicative-additive model for CT volume data segmentation

3D industrial computed tomography (ICT) technology plays a vital role in non-destructive testing and evaluation of complex components. However, CT images often suffer from artifacts and noise because the CT imaging system is non-ideal. To achieve high-precision segmentation of ICT volume data, a level set (LS) method with a 3D multiplicative-additive (MA) model was proposed. First, according to the cluster property of local intensity and the 3D-MA image model, we developed a local energy. The global energy was established by integrating the local energy. Next, the LS function was embedded into the global energy to form a variational LS energy functional. Finally, the proposed energy functional was minimized to achieve segmentation. The experimental results demonstrate that compared with the state-of-the-art models our model has superior accuracy. In particular, the measurement results of the forest ball also show that the proposed method excels in geometric measurement based on CT images.

Research Study on the Effects of Disinfectants on Medical Images and Medical Equipment in Infection Control Measures

In this study, we investigated the effects of various disinfectants used to prevent infectious diseases on medical images and medical equipment. First, we investigated the effect of residual disinfectant on medical images in CT, mammography (MMG), and general imaging systems. Acrylic discs with various disinfectants attached were photographed using each imaging device, and visual evaluation and changes in image signal values were evaluated. We also conducted a questionnaire survey of each manufacturer regarding cleaning methods for medical devices. With CT/MMG, residual disinfectant could be visually confirmed on the image. Although this could not be confirmed with the general imaging system, a significant difference was confirmed in the image signal values of the general imaging system through statistical analysis. This is thought to be largely due to the influence of nonlinearity in the short-time imaging range of general imaging equipment. In addition, from the responses to a questionnaire survey of each medical device manufacturer, we were able to understand detailed cleaning methods that are not covered in medical device instruction manuals.

Suppression of P2X7R by Local Treatment Alleviates Acute Gouty Inflammation.

Gout is the most common inflammatory arthritis associated with interleukin-1β (IL-1β) accumulation during exacerbation. In this study, we aimed to clarify whether potassium channel antagonists attenuate local inflammation in mice with monosodium urate (MSU)-induced gout. We cultured human macrophage THP-1 cells and evaluated the molecular levels of both IL-1β and potassium channels stimulated with MSU and/or potassium channel antagonists. Acute gout models were generated in IL-1β luciferase transgenic male mice using synovium-like subcutaneous air pouches with MSU injection. Their luciferase activities were monitored following potassium channel blocker treatment using the IVIS Spectrum CT imaging system. The lavages and tissues were extracted from their air pouches, followed by cell counting and pathological analysis. MSU stimulation increased the gene expression levels of pro-IL-1β, P2x7r and Kv1.3, whereas the expression of Kcnq1 was decreased in phorbol 12-myristate 13-acetate-induced THP-1 cells. Both high and low concentrations of the P2x7 receptor inhibitor adenosine 5'-triphosphate (ATP) derivative periodate oxidized ATP (oATP) decreased the production of IL-1β in the supernatant of THP-1 cells. The sixth hour was the peak time of IL-1β luciferase activity after MSU intervention in vivo. oATP ameliorated the synovial IL-1β luciferase activity, reduced inflammatory cell infiltration and alleviated the erosive damage in the cartilage. The anti-inflammatory properties of potassium channel inhibitors, especially of oATP, might point to new strategies for local anti-inflammatory therapy for acute gout.

Unconventional High-Value Utilization of Metallurgical Iron-Bearing Dust as Shielding Composite for Medical X-rays

Iron-bearing dust is one of the main solid wastes in the metallurgical industry, and currently, it is mainly disposed of according to accumulation, which brings great environmental risks. Therefore, this paper proposes a method of preparing X-ray shielding materials by hot pressing using iron-bearing dust as the filler and polyimide resin powder as the matrix. A CT imaging system was used to test the X-ray shielding performance of the materials. The results demonstrated that shielding material I-95 had a shielding percentage of more than 95% at a tube voltage of 55 kVp and a tube current of 2 mA, and the thickness of the half-value layer was less than 0.68 mm. The shielding percentage and mass attenuation coefficient of the composites showed an increasing trend with increased filler addition, tube voltage, and tube current intensity, while the half-value layer thickness showed the opposite trend. Furthermore, the shielding percentage of composites with different fillers was affected by the voltage and hardly affected by the current variation. The dominant part of the shielding material interaction across the tested tube voltage range was photoelectric absorption. The prepared composite is a low-cost material and has high efficiency and is an ideal medical X-ray shielding material.

Air Kerma Calculation in Diagnostic Medical Imaging Devices Using Group Method of Data Handling Network

The air kerma, which is the amount of energy given off by a radioactive substance, is essential for medical specialists who use radiation to diagnose cancer problems. The amount of energy that a photon has when it hits something can be described as the air kerma (the amount of energy that was deposited in the air when the photon passed through it). Radiation beam intensity is represented by this value. Hospital X-ray equipment has to account for the heel effect, which means that the borders of the picture obtain a lesser radiation dosage than the center, and that air kerma is not symmetrical. The voltage of the X-ray machine can also affect the uniformity of the radiation. This work presents a model-based approach to predict air kerma at various locations inside the radiation field of medical imaging instruments, making use of just a small number of measurements. Group Method of Data Handling (GMDH) neural networks are suggested for this purpose. Firstly, a medical X-ray tube was modeled using Monte Carlo N Particle (MCNP) code simulation algorithm. X-ray tubes and detectors make up medical X-ray CT imaging systems. An X-ray tube's electron filament, thin wire, and metal target produce a picture of the electrons' target. A small rectangular electron source modeled electron filaments. An electron source target was a thin, 19,290 kg/m3 tungsten cube in a tubular hoover chamber. The electron source-object axis of the simulation object is 20° from the vertical. For most medical X-ray imaging applications, the kerma of the air was calculated at a variety of discrete locations within the conical X-ray beam, providing an accurate data set for network training. Various locations were taken into account in the aforementioned voltages inside the radiation field as the input of the GMDH network. For diagnostic radiology applications, the trained GMDH model could determine the air kerma at any location in the X-ray field of view and for a wide range of X-ray tube voltages with a Mean Relative Error (MRE) of less than 0.25%. This study yielded the following results: (1) The heel effect is included when calculating air kerma. (2) Computing the air kerma using an artificial neural network trained with minimal data. (3) An artificial neural network quickly and reliably calculated air kerma. (4) Figuring out the air kerma for the operating voltage of medical tubes. The high accuracy of the trained neural network in determining air kerma guarantees the usability of the presented method in operational conditions.

OPTIma: a tracking solution for proton computed tomography in high proton flux environments

Currently there is a large discrepancy between the currents that are used for treatments in proton beam therapy facilities and the ultra low beam currents required for many proton CT imaging systems. Here we provide details of the OPTIma silicon strip based tracking system, which has been designed for performing proton CT imaging in conditions closer to the high proton flux environments of modern spot scanning treatment facilities. Details on the physical design, sensor testing, modelling, and track reconstruction are provided along with Monte-Carlo simulation studies of the expected performance for proton beam currents of up to 50 pA at the nozzle when using a σ= ∼10 mm spot scanning cyclotron system. Using a detailed simulation of the proposed OPTIma system, a discrepancy of less than 1% on the Relative Stopping Power is found for various tissues when embedded within a 150 mm diameter Perspex sphere. It is found that by accepting up to 7 protons per bunch it is possible to operate at cyclotron beam currents up to 5 times higher than would be possible with a single proton based readout, significantly reducing the total beam time required to produce an image, while also reducing the discrepancy between the beam currents required for treatment and those used for proton CT.

Evaluating on-board kVCT- and MVCT-based dose calculation accuracy using a thorax phantom for helical tomotherapy treatments

Purpose. To evaluate the impact of CT number calibration and imaging parameter selection on dose calculation accuracy relative to the CT planning process in thoracic treatments for on-board helical CT imaging systems used in helical tomotherapy. Methods and Materials. Direct CT number calibrations were performed with appropriate protocols for each imaging system using an electron density phantom. Large volume and SBRT treatment plans were simulated and optimized for planning CT scans of an anthropomorphic thorax phantom and transferred to registered kVCT and MVCT scans of the phantom as appropriate. Relevant DVH metrics and dose-difference maps were used to evaluate and compare dose calculation accuracy relative to the planning CT based on a variation in imaging parameters applied for the on-board systems. Results. For helical kVCT scans of the thorax phantom, median differences in DVH parameters for the large volume treatment plan were less than ±1% with dose to the target volume either over- or underestimated depending on the imaging parameters utilized for CT number calibration and thorax phantom acquisition. For the lung SBRT plan calculated on helical kVCT scans, median dose differences were up to –2.7% with a more noticeable dependence on parameter selection. For MVCT scans, median dose differences for the large volume plan were within +2% with dose to the target overestimated regardless of the imaging protocol. Conclusion. Accurate dose calculations (median errors of <±1%) using a thorax phantom simulating realistic patient geometry and scatter conditions can be achieved with images acquired with a helical kVCT system on a helical tomotherapy unit. This accuracy is considerably improved relative to that achieved with the MV-based approach. In a clinical setting, careful consideration should be made when selecting appropriate kVCT imaging parameters for this process as dose calculation accuracy was observed to vary with both parameter selection and treatment type.

Super resolution reconstruction of CT images based on multi-scale attention mechanism.

CT diagnosis has been widely used in clinic because of its special diagnostic value. The image resolution of CT imaging system is constrained by X-ray focus size, detector element spacing, reconstruction algorithm and other factors, which makes the generated CT image have some problems, such as low contrast, insufficient high-frequency information, poor perceptual quality and so on. To solve the above problems, a super-resolution reconstruction method of CT image based on multi-scale attention mechanism is proposed. First, use a 3 × 3 and a 1 × 1 convolution layer extracting shallow features. In order to better extract the high-frequency features of CT images and improve the image contrast, a multi-scale attention module is designed to adaptively detect the information of different scales, improve the expression ability of features, integrate the channel attention mechanism and spatial attention mechanism, and pay more attention to important information, retain more valuable information. Finally, sub-pixel convolution is used to improve the resolution of CT image and reconstruct high-resolution CT image. The experimental results show that this method can effectively improve the CT image contrast and suppress the noise. The peak signal-to-noise ratio and structural similarity of the reconstructed CT image are better than the comparison method, and has a good subjective visual effect.

Analysis of X-Ray Beam Hardening Correction Method Relying on Cloud Computing Big Data

Regarding the correction of X-ray beam hardening in the current CT imaging system, the traditional method will cause the overlapping of images during use, which will gradually harden the beam, and the image reconstructed by the imaging system will gradually become “cup-shaped” or “striped.” “False images” seriously degrade the quality of the images, while causing more interfering diagnostic problems. In this paper, the cloud computing big data analysis algorithm is applied to the X-ray beam hard correction process. According to the transition energy and its energy absorption, the X-ray beam is used as the cut-in point, and the relationship between the attenuation coefficient of similar materials and the X-ray energy is used to remove the artifact image in the initial image reconstruction process to obtain a clear corrected image. Meanwhile, according to the thickness and gray value of the X-ray penetrable object, the result of fitting using a polynomial function is calculated, and an accurate line fitting can be completed for data with smaller coordinates. Finally, the experimental study shows that the cloud computing big data analysis proposed in this paper can detect X-ray beams in real time. This method uses optical receivers to achieve high noise sensitivity to X-rays, and in long-distance transmission scenarios, the bandwidth of communication transmission can be maximized, and different types of formats can be used to complete modulation for different X-rays. Therefore, X-ray beam hardening correction technology has better advantages and the market application scenarios compared with other technologies.

A novel hardware duo of beam modulation and shielding toreduce scatter acquisition and dose in cone-beam breastCT.

In cone-beam breast CT, scattered photons form a large portion of the acquired signal, adversely impacting image quality throughout the frequency response of the imaging system. Prior simulation studies provided proof of concept for utilization of a hardware solution to prevent scatter acquisition. Here, we report the design, implementation, and characterization of an auxiliary apparatus of fluence modulation and scatter shielding that does indeed lead to projections with a reduced level of scatter. An apparatus was designed for permanent installation within an existing cone-beam CT system. The apparatus is composed of two primary assemblies: a "Fluence Modulator" (FM) and a "Scatter Shield" (SS). The design of the assemblies enables them to operate in synchrony during image acquisition, converting the sourced x-rays into a moving narrow beam. During a projection, this narrow beam sweeps the entire fan angle coverage of the imaging system. As the two assemblies are contingent on one another, their joint implementation is described in the singular as apparatus FM-SS. The FM and the SS assemblies are each comprised a metal housing, a sensory system, and a robotic system. A controller unit handles their relative movements. A series of comparative studies were conducted to evaluate the performance of a cone-beam CT system in two "modes" of operation: with and without FM-SS installed, and to compare the results of physical implementation with those previously simulated. The dynamic range requirements of the utilized detector in the cone-beam CT imaging system were first characterized, independent of the mode of operation. We then characterized and compared the spatial resolution of the imaging system with, and without, FM-SS. A physical breast phantom, representative of an average size breast, was developed and imaged. Actual differences in signal level obtained with, versus without, FM-SS were then compared to the expected level gains based on previously reported simulations. Following these initial assessments, the scatter acquisition in each projection in both modes of operation was investigated. Finally, as an initial study of the impact of FM-SS on radiation dose in an average size breast, a series of Monte Carlo simulations were coupled with physical measurements of air kerma, with and without FM-SS. With implementation of FM-SS, the detector's required dynamic range was reduced by a factor of 5.5. Substantial reduction in the acquisition of the scattered rays, by a factor of 5.1 was achieved. With the implementation of FM-SS, deposited dose was reduced by 27% in the studied breast. The disclosed implementation of FM-SS, within a cone-beam breast CT system, results in reduction of scatter-components in acquired projections, reduction of dose deposit to the breast, and relaxation of requirements for the detector's dynamic range. Controlling or correcting for patient motion occurring during image acquisition remains an open problem to be solved prior to practical clinical usage of FM-SS cone-beam breast CT.

Knowledge-based self-calibration method of calibration phantom by and for accurate robot-based CT imaging systems

Modern X-ray imaging system with feature of low-dose and high spatial resolution imaging has become a prevalent noninvasive imaging technique in clinic. High-resolution imaging of cone-beam computed tomography (CBCT) system crucially relies on accurate geometric calibration. Accurate coordinates of bearing balls (BBs) on calibration phantom are essential prerequisites to precisely realize geometric calibration of CBCT systems. However, due to phantom-making error, BB position deviations may occur between the actual value and theoretical value, further resulting in estimation error of realistic parameters in geometric calibration. Current algorithms that can estimate BB coordinates are insufficient and not robust. In this study, we proposed a knowledge-based self-calibration method by means of a robot-based CT system to fill the vacancy. The moving knowledge from one single manipulator of dual manipulators is utilized for automatic self-calibration of the calibration phantom, which is then for accurate geometry calibration for the dual manipulator-based imaging system. Specifically, different projections of BBs can be obtained by moving the robotic manipulator, on which X-ray tube is installed several times, while the detector and the calibration phantom remain stationary. Hence, the actual BB coordinates can be estimated by minimizing two separate cost functions determined by reprojection errors and relocation errors of BBs. Simulation study shows that the mean of absolute distance values of the estimated coordinates are 0, 0.0164, and 0.0190 mm, and the standard deviation values of Gaussian noise are 0%, 10%, and 15% of a single pixel size on BB projection, respectively. Experiments demonstrate that the image quality of the reconstructed results has been improved to a large extent after utilizing the proposed self-calibration method. The performance is even superior to that of images acquired by performing geometric calibration on a high-precise calibration phantom with more BBs. The proposed method provides a flexible utility value to acquire high precision geometry and generate high-quality images for CBCT systems.

The authentication and repatriation of a ceremonial tsantsa to its country of origin (Ecuador)

Tsantsas, commonly referred to as “shrunken heads”, are unique and valuable antiquities that were produced by the Shuar, Achuar, Awajún/Aguaruna, Wampís/Huambisa, and Candoshi-Shampra (SAAWC) peoples until the mid twentieth century. Originally used with ceremonial purpose during important social group functions, tsantsas became monetarily valuable as keepsakes and curios during the nineteenth century as a result of Western/European cultural encroachment. Unmet demand resulted in the production of convincing forgeries that created confusion about the authenticity of existing collections. Ceremonial tsantsas are both human remains and valuable cultural items. Their production and purpose were negatively influenced by colonialism and the outside curio market; as such many institutions may choose to repatriate them to their places of origin. Herein, we report on the authentication and repatriation of a ceremonial tsantsa recently rediscovered in a university’s natural history collection. The personal memoirs of the original collector describe that it originated in the Ecuadorean Amazon. In consultation with the government of Ecuador, it was determined that authentication was required prior to repatriation. The tsantsa was compared to a list of thirty-three distinct characteristics shared by ceremonial tsantsas. These criteria were taken from those provided by Ecuador’s National Cultural Heritage Institute and those found in prior studies from the academic literature; they include notable skin and hair features, structure and facial anatomy, and evidence of traditional fabrication and modification. We were able to affirm 30 of the 33 authenticating indicators. As part of our protocol the tsantsa was scanned with a CT-imaging system. The resulting 3D images were invaluable in discerning subtle and difficult-to-visualize characteristics regarding the skin and patterns of modification, although there are limitations related to the small size of filamentous structures. The results of the authentication were accepted by the Ecuadorean government, and the tsantsa was repatriated in June 2019. An additional benefit of CT-imaging is that data files can be generated in order to create rapid prototypes via 3D printing. In fact, as our work demonstrates, artifacts of value can be repatriated while simultaneously preserved as a volumetric replica for the purposes of a collection.

CT Image Changes of Severe Acute Pancreatitis Based on Smart Electronic Medical Augmented Reality in Nursing Practice.

Severe acute pancreatitis (SAP) is traditionally treated with chemical analysis. Faced with the increasing maturity of CT imaging technology, it is necessary to use more advantageous CT imaging to treat SAP. In this article, 72 SAP patients admitted to the Affiliated Hospital of Southwest Medical University were selected for study, of which 62 were severely ill, 8 were exacerbated, and 2 changed from severe to mild. This article combines the patient's case records and related CT images during treatment from the perspective of nursing and conducts nursing research on the application of CT image changes in severe acute pancreatitis in nursing practice. CT image processing uses CT imaging system workstation (DICOM). The results of the study showed that, in the care of patients, 21 cases had recurrence after internal drainage, and the cure rate was 91.1%. Internal drainage is an effective way to treat SAP. The higher the incidence of pancreatitis, the more likely it is to relapse after SAP internal drainage, which may be related to repeated episodes of pancreatitis and repeated inflammation of the pancreas and pancreatic duct damage. 4 of the relapsed cases in this article are postchronic pancreatitis SAP, and the relapsed cases account for 50% of the chronic pancreatic cases. This may be due to chronic fibrosis of the branched and main pancreatic ducts, continuous abnormal pancreatic juice drainage. Therefore, it is necessary to further explore the prognosis of different causes of SAP. In terms of complication care, the overall complication rate was 16.6%. One patient died of postoperative hemorrhage. Analysis of the causes of cyst recurrence and complications may be closely related to the mechanism of the occurrence and development of SAP. The initiating factor of SAP is that the pancreatic tissue is damaged due to inflammation, trauma, or microcirculation disorder, and then the pancreatic juice leaks out of the pancreas, wrapping the pancreatic juice; it takes a certain time for the capsule of fibrous knot tissue to form and strengthen.

UCT 760 CT Imaging System

Biomedical Safety & Standards 50(17):p 134, October 01, 2020. | DOI: 10.1097/01.BMSAS.0000717512.38405.5b

Application of CS in weak signal quantum measurement and protein structure calculation

It has been more than 15 years since the compressed sensing (CS) theory was put forward in 2006. The CS theory has been successfully applied and developed in many classical fields such as the single-pixel camera, CT imaging and radar imaging system, but there is still much space for its applications in quantum and biological system. In this paper, the basic knowledge of CS theory and its application/development history are briefly introduced. Then a review is given on a series of achievements in the CS theory applied in quantum precision measurement and biological system, mainly obtained by the Center for Quantum Technology Research in Beijing Institute of Technology (BIT). The review covers several different topics including the measurement and imaging in extremely weak signals, the density matrix calculation for multi-body quantum state tomography and the protein structure reconstruction from matrix completion theory, which is developed based on the CS theory. With the above reviews, we show that the CS theory has great potential for further application, not only in weak signal detection, but also in quantum calculation and even the research on bio-macromolecules. In the end, the summary and outlook are given on the future developments and applications of the CS theory.