High-resolution Mode Research Articles

Performance evaluation of a high-resolution brain PET scanner using four-layer MPPC DOI detectors

A high-resolution positron emission tomography (PET) scanner, dedicated to brain studies, was developed and its performance was evaluated. A four-layer depth of interaction detector was designed containing five detector units axially lined up per layer board. Each of the detector units consists of a finely segmented (1.2 mm) LYSO scintillator array and an 8 × 8 array of multi-pixel photon counters. Each detector layer has independent front-end and signal processing circuits, and the four detector layers are assembled as a detector module. The new scanner was designed to form a detector ring of 430 mm diameter with 32 detector modules and 168 detector rings with a 1.2 mm pitch. The total crystal number is 655 360. The transaxial and axial field of views (FOVs) are 330 mm in diameter and 201.6 mm, respectively, which are sufficient to measure a whole human brain. The single-event data generated at each detector module were transferred to the data acquisition servers through optical fiber cables. The single-event data from all detector modules were merged and processed to create coincidence event data in on-the-fly software in the data acquisition servers. For image reconstruction, the high-resolution mode (HR-mode) used a 1.2 mm2 crystal segment size and the high-speed mode (HS-mode) used a 4.8 mm2 size by collecting 16 crystal segments of 1.2 mm each to reduce the computational cost. The performance of the brain PET scanner was evaluated. For the intrinsic spatial resolution of the detector module, coincidence response functions of the detector module pair, which faced each other at various angles, were measured by scanning a 0.25 mm diameter 22Na point source. The intrinsic resolutions were obtained with 1.08 mm full width at half-maximum (FWHM) and 1.25 mm FWHM on average at 0 and 22.5 degrees in the first layer pair, respectively. The system spatial resolutions were less than 1.0 mm FWHM throughout the whole FOV, using a list-mode dynamic RAMLA (LM-DRAMA). The system sensitivity was 21.4 cps kBq−1 as measured using an 18F line source aligned with the center of the transaxial FOV. High count rate capability was evaluated using a cylindrical phantom (20 cm diameter × 70 cm length), resulting in 249 kcps in true and 27.9 kcps at 11.9 kBq ml−1 at the peak count in a noise equivalent count rate (NECR_2R). Single-event data acquisition and on-the-fly software coincidence detection performed well, exceeding 25 Mcps and 2.3 Mcps for single and coincidence count rates, respectively. Using phantom studies, we also demonstrated its imaging capabilities by means of a 3D Hoffman brain phantom and an ultra-micro hot-spot phantom. The images obtained were of acceptable quality for high-resolution determination. As clinical and pre-clinical studies, we imaged brains of a human and of small animals.

Finite element model updating of liquid rocket engine nozzle based on modal test results obtained from 3-D SLDV technique

In order to update the finite element model, the modal test results must be highly accurate since they are used as the basis. The major problems with traditional modal test method are limited measurement points and poor mode shape precision. In this paper, modal test based on 3-D Scanning Laser Doppler Vibrometry (SLDV) technique was carried out. High spatial resolution and accurate mode shapes were obtained, which is beneficial to subsequent correlation analysis and updating process. High order modal parameters were identified and more information can be added in the objective function. Due to the consistent coordinate system in modal test and finite element model, the measurement points and corresponding finite element nodes were easily matched in order to compare mode shapes. By means of a real liquid rocket engine nozzle, an integrated model updating process is presented from proper initial model, accurate modal test results, test/analysis correlation to automatic model updating. The single steps of detailed updating process are highlighted. The discrepancy between the finite element model predicted and the experiment measured modal parameters are minimized and satisfactory results were obtained.

Improved nickel-corrected isotopic analysis of iron using high-resolution multi-collector inductively coupled plasma mass spectrometry

Herein, we describe the use of a Nu Plasma 1700 multi-collector inductively coupled plasma mass spectrometer (MC-ICP-MS) in true high-resolution mode to determine Fe isotopic ratios at the center of Fe peaks instead of their shoulders. A standard-sample bracketing (SSB) technique and a Ni doping method were used for instrumental mass bias calibration. The effects of Fe/Ni ratio and plasma mode were investigated in order to establish a high-precision Fe isotope analysis method. The results showed that the Ni-doping method provided more precision isotopic ratios than that of the SSB technique. Moreover, this work also presents Fe isotopic compositions of some geological reference materials (BCR-2, BHVO-2, AGV-2, GSR-1, GSR-2, GSR-3, GSP-2, and DSN-1), which were highly accurate with respect to the international Fe isotope standard IRMM-014. The iron isotopic compositions of most geological reference materials measured in this study agreed with the previously published data within quoted analytical uncertainties. Long-term reproducibility analyses of all samples indicate that the obtained isotopic ratios are highly reproducible, with precisions of better than ±0.03‰ for δ56Fe (2 sd) and ±0.06‰ (2 sd) for δ57Fe. Our results demonstrated the usefulness of internal element doping for improving the stability and precision of isotope analysis by MC-ICP-MS.

Auditory responses to short-wavelength infrared neural stimulation of the rat cochlear nucleus.

Pulsed Infrared laser is well-known for its high spatial resolution and contact-free stimulation mode. In order to improve the current auditory brainstem implants (ABI), 980 nm-short-wavelength infrared light was applied to stimulate the cochlear nucleus of rats. Single neural activity from contralateral inferior colliculus was recorded during laser stimulation. Animal experimental results showed that 980 nm laser could not directly activate neurons in cochlear nucleus and a photo-acoustic response was observed during stimulation, however, 980 nm laser produces an inhibitory effect on neural responses to sounds; After we added carbon nanoparticles onto the surface of animal cochlear nucleus, 980 nm laser could directly stimulate neurons and no interference between adjacent recording channels was observed. These findings indicated that with the enhancement of carbon nanoparticles, short-wavelength infrared neural stimulation (SW-INS) might be an effective method to overcome the defects of current ABIs. With this method, a new type of optical ABI with transcutaneous stimulating method is quite promising.

Untargeted analysis to monitor metabolic changes of garlic along heat treatment by LC-QTOF MS/MS.

Black garlic is increasing its popularity in cuisine around the world; however, scant information exists on the composition of this processed product. In this study, polar compounds in fresh garlic and in samples taken at different times during the heat treatment process to obtain black garlic have been characterized by liquid chromatography coupled to tandem mass spectrometry in high resolution mode. Ninety-five compounds (mainly amino acids and metabolites, organosulfur compounds, and saccharides and derivatives) were tentatively identified in all the analysed samples and classified as a function of the family they belong to. Statistical analysis of the results allowed establishing that the major changes in garlic occur during the first days of treatment, and they mainly affect to the three representative families. The main pathways involved in the synthesis of the compounds affected by heat treatment, and their evolution during the process were studied.

Preclinical Testing of Frequency-Tunable Capacitive Micromachined Ultrasonic Transducer Probe Prototypes

In intracardiac echocardiography (ICE) it may be beneficial to generate ultrasound images acquired at multiple frequencies, having the possibility of high penetration or high-resolution imaging in a single device. The objective of the presented work is to test two frequency-tunable probe prototypes in a preclinical setting: a rigid probe having a diameter of 11 mm and a new flexible and steerable 12-Fr ICE catheter. Both probes feature a forward-looking 32-element capacitive micromachined ultrasonic transducer array (aperture of 2 × 2 mm2) operated in collapse mode, which allows for frequency tuning in the 6-MHz–18-MHz range. The rigid probe prototype is tested ex vivo in a passive heart platform. Images of an aortic valve acquired in high-penetration (6 MHz), generic (12 MHz) and high-resolution (18 MHz) mode combine satisfying image quality and penetration depth between 2.5 cm and 10 cm. The ICE catheter prototype is tested in vivo using a porcine animal model. Images of an aortic valve are acquired in the 3 imaging modes with the ICE catheter placed in an ascending aorta at multiple depths. It was found that the combination of the forward-looking design and frequency-tuning capability allows visualizing intracardiac structures of various sizes at different distances relative to the catheter tip, providing both wide overviews and detailed close-ups.

Crystal Initiation Structures in Developing Enamel: Possible Implications for Caries Dissolution of Enamel Crystals.

Investigations of developing enamel crystals using Atomic and Chemical Force Microscopy (AFM, CFM) have revealed a subunit structure. Subunits were seen in height images as collinear swellings about 30 nM in diameter on crystal surfaces. In friction mode they were visible as positive regions. These were similar in size (30–50 nM) to collinear spherical structures, presumably mineral matrix complexes, seen in developing enamel using a freeze fracturing/freeze etching procedure. More detailed AFM studies on mature enamel suggested that the 30–50 nM structures were composed of smaller units, ~10–15 nM in diameter. These were clustered in hexagonal or perhaps a spiral arrangement. It was suggested that these could be the imprints of initiation sites for mineral precipitation. The investigation aimed at examining original freeze etched images at high resolution to see if the smaller subunits observed using AFM in mature enamel were also present in developing enamel i.e., before loss of the organic matrix. The method used was freeze etching. Briefly samples of developing rat enamel were rapidly frozen, fractured under vacuum, and ice sublimed from the fractured surface. The fractured surface was shadowed with platinum or gold and the metal replica subjected to high resolution TEM. For AFM studies high-resolution tapping mode imaging of human mature enamel sections was performed in air under ambient conditions at a point midway between the cusp and the cervical margin. Both AFM and freeze etch studies showed structures 30–50 nM in diameter. AFM indicated that these may be clusters of somewhat smaller structures ~10–15 nM maybe hexagonally or spirally arranged. High resolution freeze etching images of very early enamel showed ~30–50 nM spherical structures in a disordered arrangement. No smaller units at 10–15 nM were clearly seen. However, when linear arrangements of 30–50 nM units were visible the picture was more complex but also smaller units including ~10–15 nM units could be observed.Conclusions: Structures ~10–15 nM in diameter were detected in developing enamel. While the appearance was complex, these were most evident when the 30–5 nM structures were in linear arrays. Formation of linear arrays of subunits may be associated with the development of mineral initiation sites and attendant processing of matrix proteins.

Very efficient spin polarization analysis (VESPA): new exchange scattering-based setup for spin-resolved ARPES at APE-NFFA beamline at Elettra.

Complete photoemission experiments, enabling measurement of the full quantum set of the photoelectron final state, are in high demand for studying materials and nanostructures whose properties are determined by strong electron and spin correlations. Here the implementation of the new spin polarimeter VESPA (Very Efficient Spin Polarization Analysis) at the APE-NFFA beamline at Elettra is reported, which is based on the exchange coupling between the photoelectron spin and a ferromagnetic surface in a reflectometry setup. The system was designed to be integrated with a dedicated Scienta-Omicron DA30 electron energy analyzer allowing for two simultaneous reflectometry measurements, along perpendicular axes, that, after magnetization switching of the two targets, allow the three-dimensional vectorial reconstruction of the spin polarization to be performed while operating the DA30 in high-resolution mode. VESPA represents the very first installation for spin-resolved ARPES (SPARPES) at the Elettra synchrotron in Trieste, and is being heavily exploited by SPARPES users since autumn 2015.

Proper orthogonal decomposition-based spatial refinement of TR-PIV realizations using high-resolution non-TR-PIV measurements

A proper orthogonal decomposition (POD)-based spatial refinement approach is proposed to increase the resolution of time-resolved particle image velocimetry (TR-PIV) realizations. POD analysis of the high-resolution non-TR-PIV measurements is used to construct the high-resolution POD modes, and the TR-PIV instantaneous realization with relatively low spatial resolution is cross-projected onto the POD modes to obtain the time-varying mode coefficients. Subsequently, the high-resolution time-resolved flow fields, which inherit the information of the superimposed multi-scale structures from the non-TR-PIV measurements, are reconstructed using the linear combination of the cross-projected mode coefficients and the corresponding high-resolution POD modes. Two main sources of error in the novel strategy are discussed: the cross-projected reconstruction of the instantaneous fields, which are excluded in the determination of the high-resolution POD modes, and the interpolation that maps the high-resolution POD modes onto the coarse grid in the cross-projection process when estimating the mode coefficients. To evaluate the method, the flow fields of a free round jet at Reynolds number $$Re$$ = 3000 are separately measured in the same field-of-view region using non-TR-PIV and TR-PIV setups with a spatial resolution ratio of 42:1. The high- and low-resolution realizations of the instantaneous flow fields measured by the non-TR-PIV setup are determined by applying fine (32 × 32 pixels) and coarse (128 × 128 pixels) interrogation windows, respectively, to ensure accurate fine-to-coarse mapping of the POD modes and for use as a reference to assess the refinement accuracy. This evaluation shows that the combination of these two error sources can be minimized when the POD-sample size (the number of snapshots employed in the decomposition) and the number of POD modes for refinement are optimized. Finally, application of the present method to TR-PIV data shows that the high-resolution time-resolved fields are successfully achieved with the temporal pattern similar to the original TR-PIV realizations, while much smaller structures are captured by the spatially refined flow.

Establishing compositional differences between fresh and black garlic by a metabolomics approach based on LC–QTOF MS/MS analysis

Despite the increasing popularity of black garlic as a food ingredient, few studies have been devoted to in-depth profiling characterization of this product from fresh garlic. In this research polar extracts from fresh and black garlic of three garlic varieties cultivated in the South of Spain were characterized using liquid chromatography with tandem mass spectrometry in high resolution mode with a QTOF analyzer. Ninety-eight compounds were tentatively identified and classified as a function of the given family: amino acids and derivatives, organosulfur compounds, saccharides and derivatives, lipids and derivatives, and others. The composition of the three garlic varieties was compared and the differences among them evaluated. Then, fresh and black garlic were compared to determine the compounds that are exclusive of each one and also the compounds with levels significantly different among them. The heat treatment changes significantly the composition in garlic of the amino acids family, followed by organosulfur compounds.

Reference-free detection of minute, non-visible, damage using full-field, high-resolution mode shapes output-only identified from digital videos of structures

Detecting damage in structures based on the change in their dynamics or modal parameters (modal frequencies and mode shapes) has been extensively studied for three decades. The success of such a global, passive, vibration-based method in field applications, however, has long been hindered by the bottleneck of low spatial resolution vibration sensor measurements. The primary reason is that damage typically initiates and develops in local regions that need to be captured and characterized by very high spatial resolution vibration measurements and modal parameters (mode shapes), which are extremely difficult to obtain using traditional vibration measurement techniques. For example, accelerometers and strain-gauge sensors are typically placed at a limited number of discrete locations, providing low spatial resolution vibration measurements. Laser vibrometers provide high-resolution measurements, but are expensive and make sequential measurements that are time- and labor-consuming. Recently, digital video cameras—which are relatively low cost, agile, and able to provide high spatial resolution, simultaneous, pixel measurements—have emerged as a promising tool to achieve full-field, high spatial resolution vibration measurements. Combined with advanced vision processing and unsupervised machine algorithms, a new method has recently been developed to blindly and efficiently extract the full-field, high-resolution, dynamic parameters from the video measurements of an operating, output-only structure. This work studies the feasibility of performing damage detection using the full-field, very high spatial resolution mode shape (of the fundamental mode) blindly extracted from the video of the operating (output-only) structure without any knowledge of reference (healthy) structural information. A spatial fractal dimension analysis is applied on the full-field mode shape of the damaged structure to detect damage-induced irregularity. Additionally, the equivalence between the fractal dimension and the squared curvature (modal strain energy) of the mode shape curve, when of high spatial resolution, is mathematically derived. Laboratory experiments are conducted on bench-scale structures, including a building structure and a cantilever beam, to validate the approach. The results illustrate that using the full-field, very high-resolution mode shape enables detection of minute, non-visible, damage in a global, completely passive sensing manner, which was previously not possible to achieve.

Ice mass change in Greenland and Antarctica between 1993 and 2013 from satellite gravity measurements

We construct long-term time series of Greenland and Antarctic ice sheet mass change from satellite gravity measurements. A statistical reconstruction approach is developed based on a principal component analysis (PCA) to combine high-resolution spatial modes from the Gravity Recovery and Climate Experiment (GRACE) mission with the gravity information from conventional satellite tracking data. Uncertainties of this reconstruction are rigorously assessed; they include temporal limitations for short GRACE measurements, spatial limitations for the low-resolution conventional tracking data measurements, and limitations of the estimated statistical relationships between low- and high-degree potential coefficients reflected in the PCA modes. Trends of mass variations in Greenland and Antarctica are assessed against a number of previous studies. The resulting time series for Greenland show a higher rate of mass loss than other methods before 2000, while the Antarctic ice sheet appears heavily influenced by interannual variations.

Lung Nodule Volume Quantification and Shape Differentiation with an Ultra-High Resolution Technique on a Photon Counting Detector CT System.

A new ultra high-resolution (UHR) mode has been implemented on a whole body photon counting-detector (PCD) CT system. The UHR mode has a pixel size of 0.25 mm by 0.25 mm at the iso-center, while the conventional (macro) mode is limited to 0.5 mm by 0.5 mm. A set of synthetic lung nodules (two shapes, five sizes, and two radio-densities) was scanned using both the UHR and macro modes and reconstructed with 2 reconstruction kernels (4 sets of images in total). Linear regression analysis was performed to compare measured nodule volumes from CT images to reference volumes. Surface curvature was calculated for each nodule and the full width half maximum (FWHM) of the curvature histogram was used as a shape index to differentiate sphere and star shape nodules. Receiver operating characteristic (ROC) analysis was performed and area under the ROC curve (AUC) was used as a figure of merit for the differentiation task. Results showed strong linear relationship between measured nodule volume and reference standard for both UHR and macro mode. For all nodules, volume estimation was more accurate using UHR mode with sharp kernel (S80f), with lower mean absolute percent error (MAPE) (6.5%) compared with macro mode (11.1% to 12.9%). The improvement of volume measurement from UHR mode was more evident particularly for small nodule size (3mm, 5mm), or star-shape nodules. Images from UHR mode with sharp kernel (S80f) consistently demonstrated the best performance (AUC = 0.85) when separating star from sphere shape nodules among all acquisition and reconstruction modes. Our results showed the advantages of UHR mode on a PCD CT scanner in lung nodule characterization. Various clinical applications, including quantitative imaging, can benefit substantially from this high resolution mode.

다중대역 SweepSAR 운용 모드의 시스템 성능 분석

In this paper, we analyze the main performance of satellite’s Synthetic Aperture Radar system for high resolution and wide swath. We have used the radiation pattern of reflector antenna with array feed and comparison between the conventional ScanSAR mode and SweepSAR mode has been carried out. The SweepSAR mode is a high-resolution wide-swath mode that transmits beams over a wide range and receives echo signals through sequential beamforming based on SCORE(SCan On REceive). In this paper, we analyzed the operating principle and characteristics of satellite’s SweepSAR mode and simulate system performances. In addition, in order to increase the utilization of image, performances analysis for multiple frequency bands(C-band, X-band) has been considered.

Optimization of a method for the determination of a mustard gas biomarker in human blood plasma by liquid chromatography–high-resolution mass spectrometry

A method for the determination of a mustard gas biomarker (an S-hydroxyethylthioethyl adduct with albumin) in blood plasma was optimized with the use of HPLC with high-resolution tandem mass-spectrometric detection. This method is based on the hydrolysis of this adduct by the proteinase K enzyme with the formation of the following stable tripeptide with cysteine, proline, and phenylalanine: S-[HETE]-Cys- Pro-Phe. The conditions of the sample preparation of human plasma artificially contaminated by mustard gas (the selection of an aliquot portion volume and an enzyme for the hydrolysis), the mass-spectrometric detection (the selection of optimum pairs of ion reactions and high-resolution detection modes), and the gradient elution program in the HPLC separation of an analyzed mixture were optimized. The detection limit of mustard gas in human blood plasma was 1 ng/mL. The approach proposed was tested in the analysis of human blood plasma samples by the standard addition technique and also within the framework of the first official biomedical test carried out by the Organization for the Prohibition of Chemical Weapons (OPCW) in 2016, and it exhibited a good accuracy, reproducibility, and specificity of determination.

HR-COSMOS: Kinematics of star-forming galaxies at z ~ 0.9

We present the kinematic analysis of a sub-sample of 82 galaxies at 0.75 < z < 1.2 from our new survey HR-COSMOS aimed to obtain the first statistical sample to study the kinematics of star-forming galaxies in the treasury COSMOS field at 0 < z < 1.2. We observed 766 emission line galaxies using the multi-slit spectrograph ESO-VLT/VIMOS in high-resolution mode (R = 2500). To better extract galaxy kinematics, VIMOS spectral slits have been carefully tilted along the major axis orientation of the galaxies, making use of the position angle measurements from the high spatial resolution HST/ACS COSMOS images. We constrained the kinematics of the sub-sample at 0.75 < z < 1.2 by creating high-resolution semi-analytical models. We established the stellar-mass Tully-Fisher relation at z ≃ 0.9 with high-quality stellar mass measurements derived using the latest COSMOS photometric catalog, which includes the latest data releases of UltraVISTA and Spitzer. In doubling the sample at these redshifts compared with the literature, we estimated the relation without setting its slope, and found it consistent with previous studies in other deep extragalactic fields assuming no significant evolution of the relation with redshift at z ≲ 1. We computed dynamical masses within the radius R2.2 and found a median stellar-to-dynamical mass fraction equal to 0.2 (assuming Chabrier IMF), which implies a contribution of gas and dark matter masses of 80% of the total mass within R2.2, in agreement with recent integral field spectroscopy surveys. We find no dependence of the stellar-mass Tully-Fisher relation with environment probing up to group scale masses. This study shows that multi-slit galaxy surveys remain a powerful tool to derive kinematics for large numbers of galaxies at both high and low redshift.

Morphological and magnetic properties of sol-gel synthetized meso and macroporous spheres of barium hexaferrite (BaFe12O19)

Porous spherical aggregates of barium hexaferrite (BaFe12O19) with 1.5µm in diameter were synthetized by the surfactant-assisted sol-gel method. The surfactant Tween20 (C58H114O26), which enables mesoporous structures, as well as polystyrene spheres (PS), as the template agent for the formation of macropores, were used. Two synthetic routes (hereafter named A and B), whose difference was the absence or presence of PS, were followed for synthesis. X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) in high resolution mode (HRTEM) were used for characterization. Size and morphology of the spheres were similar in both cases and they resemble a nest or ball-of-yarn type structure. Pore size and BaFe12O19 crystal size produced by the two routes are different. The magnetic properties of the spheres were evaluated using a vibrating sample magnetometer (VSM) as function of the calcination temperature. The spheres present ferromagnetic behavior in both routes.

Development of a multimodal foveated endomicroscope for the detection of oral cancer.

A multimodal endomicroscope was developed for cancer detection that combines hyperspectral and confocal imaging through a single foveated objective and a vibrating optical fiber bundle. Standard clinical examination has a limited ability to identify early stage oral cancer. Optical detection methods are typically restricted by either achievable resolution or a small field-of-view. By combining high resolution and widefield spectral imaging into a single probe, a device was developed that provides spectral and spatial information over a 5 mm field to locate suspicious lesions that can then be inspected in high resolution mode. The device was evaluated on ex vivo biopsies of human oral tumors.

Renal Stone Characterization using High Resolution Imaging Mode on a Photon Counting Detector CT System.

In addition to the standard-resolution (SR) acquisition mode, a high-resolution (HR) mode is available on a research photon-counting-detector (PCD) whole-body CT system. In the HR mode each detector consists of a 2x2 array of 0.225 mm × 0.225 mm subpixel elements. This is in contrast to the SR mode that consists of a 4x4 array of the same sub-elements, and results in 0.25 mm isotropic resolution at iso-center for the HR mode. In this study, we quantified ex vivo the capabilities of the HR mode to characterize renal stones in terms of morphology and mineral composition. Forty pure stones - 10 uric acid (UA), 10 cystine (CYS), 10 calcium oxalate monohydrate (COM) and 10 apatite (APA) - and 14 mixed stones were placed in a 20 cm water phantom and scanned in HR mode, at radiation dose matched to that of routine dual-energy stone exams. Data from micro CT provided a reference for the quantification of morphology and mineral composition of the mixed stones. The area under the ROC curve was 1.0 for discriminating UA from CYS, 0.89 for CYS vs COM and 0.84 for COM vs APA. The root mean square error (RMSE) of the percent UA in mixed stones was 11.0% with a medium-sharp kernel and 15.6% with the sharpest kernel. The HR showed qualitatively accurate characterization of stone morphology relative to micro CT.

Cone beam computed tomography image optimization to detect root fractures in endodontically treated teeth: an in vitro (phantom) study

The aim of this study was to evaluate the effect of an optimization filter (OF) and voxel size on the accuracy of root fracture detection. Half of 40 endodontically treated roots were fractured, and the other half were left intact. All teeth were randomly placed into 5 bovine ribs. Each rib was scanned with the Planmeca ProMax 3-D using 4 different settings: 75μm and 100μm voxel size with and without an OF. Five reviewers reported if a fracture was present by using a 5-point scale. Intra-/interobserver agreement, area under the receiver operative characteristic curve, accuracy, sensitivity, and false-positive rates were analyzed. High κ-values indicated strong intra-/interobserver agreement. There was no significant difference in fracture detection between any of the evaluated techniques. Because of the decreased cost, dose area product, and time required, compared with the other imaging modalities studied, the high-resolution mode (100μm) without an OF is recommended for root fracture detection in endodontically treated teeth.