Application Of Tomography Research Articles

Planar liquid crystal optics for axial focus shaping with an adjustable intensity and a high efficiency.

In this Letter, we report the application of planar liquid crystal (LC) devices in axial focus shaping, proving that LC diffractive optical elements (DOEs) can achieve continuous adjustment of a symmetrical axial light field by changing the ellipticity of the incident light and can flexibly and quickly achieve various axial light field designs through an axial iterative Fourier transform algorithm. The LC DOE achieves a quasi-continuous phase and an extremely high transmittance (98.6% at 1030 nm), which makes the focusing efficiency of the LC DOE with two segments of uniform focal depths as high as 84%. The experimental results demonstrate the accurate optical field shaping effect and the axial intensity adjustable ability of LC DOE, indicating potential applications in optical tomography and precision manufacturing, among others.

Broadband wavelength-swept Cr4+:YAG crystal fiber laser.

We present a broadband wavelength-swept laser using a 16-µm-core-diameter Cr4+:YAG crystal fiber as the gain medium. The laser-diode-pumped crystal fiber laser has a threshold of only 102 mW due to the low propagation loss and high heat dissipation efficiency. The laser achieves a sweeping wavelength range of 134 nm, centered around 1425 nm, with a scanning speed of 163 k nm/s. Notably, the cross-polarization-coupled excited state absorption of the signal wavelength constrained the long-wavelength lasing limit. This laser has the potential for swept source optical coherence tomography applications, providing an axial resolution of 11.4 µm.

Characterization of single- and multi-energy CT performance of an oral dark borosilicate contrast media using a clinical photon-counting-detector CT platform.

The feasibility of oral dark contrast media is under exploration in abdominal computed tomography (CT) applications. One of the experimental contrast media in this class is dark borosilicate contrast media (DBCM), which has a CT attenuation lower than that of intra-abdominal fat. To evaluate the performances of DBCM using single- and multi-energy CT imaging on a clinical photon-counting-detector CT (PCD-CT). Five vials, three with iodinated contrast agent (5, 10, and 20mg/mL; Omnipaque 350) and two with DBCM (6% and 12%; Nextrast, Inc.), and one solid-water rod (neutral contrast agent) were inserted into two multi-energy CT phantoms, and scanned on a clinical PCD-CT system (NAEOTOM Alpha) at 90, 120, 140, Sn100, and Sn140 kV (Sn: tin filter) in multi-energy mode. CARE keV IQ level was 180 (CTDIvol: 3.0 and 12.0 mGy for the small and large phantoms, respectively). Low-energy threshold images were reconstructed with a quantitative kernel (Qr40, iterative reconstruction strength 2) and slice thickness/increment of 2.0/2.0mm. Virtual monoenergetic images (VMIs) were reconstructed from 40 to 140keV at 10keV increments. On all images, average CT numbers for each vial/rod were measured using circular region-of-interests and averaged over eight slices. The contrast-to-noise ratio (CNR) of iodine (5mg/mL) against DBCM was calculated and plotted against tube potential and VMI energy level, and compared to the CNR of iodine against water. Similar analyses were performed on iodine maps and VNC images derived from the multi-energy scan at 120kV. With increasing kV or VMI keV, the negative HU of DBCM decreased only slightly, whereas the positive HU of iodine decreased across all contrast concentrations and phantom sizes. CT numbers for DBCM decreased from -178.5±9.6 to -194.4±6.3 HU (small phantom) and from -181.7±15.7 to -192.1±11.9 HU (large phantom) for DBCM-12% from 90 to Sn140 kV; on VMIs, the CT numbers for DBCM decreased minimally from -147.1±15.7 to -185.1±9.2 HU (small phantom) and -158.8±28.6 to -188.9±14.7 HU (large phantom) from 40 to 70keV, but remained stable from 80 to 140keV. The highest iodine CNR against DBCM in low-energy threshold images was seen at 90 or Sn140 kV for the small phantom, whereas all CNR values from low-energy threshold images for the large phantom were comparable. The CNR values of iodine against DBCM computed on VMIs were highest at 40 or 70keV depending on iodine and DBCM concentrations. The CNR values of iodine against DBCM were consistently higher than iodine to water (up to 460% higher dependent on energy level). Further, the CNR of iodine compared to DBCM is less affected by VMI energy level than the identical comparison between iodine and water: CNR values at 140keV were reduced by 46.6% (small phantom) or 42.6% (large phantom) compared to 40keV; CNR values for iodine compared to water were reduced by 86.3% and 83.8% for similar phantom sizes, respectively. Compared to 70keV VMI, the iodine CNR against DBCM was 13%-79% lower on iodine maps and VNC. When evaluated at different tube potentials and VMI energy levels using a clinical PCD-CT system, DBCM showed consistently higher CNR compared to iodine versus water (a neutral contrast).

The cryo-EM 3D image reconstruction of isolated Lethocerus indicus Z-discs.

The Z-disk of striated muscle defines the ends of the sarcomere, which repeats many times within the muscle fiber. Here we report application of cryoelectron tomography and subtomogram averaging to Z-disks isolated from the flight muscles of the large waterbug Lethocerus indicus. We use high salt solutions to remove the myosin containing filaments and use gelsolin to remove the actin filaments of the A- and I-bands leaving only the thin filaments within the Z-disk which were then frozen for cryoelectron microscopy. The Lethocerus Z-disk structure is similar in many ways to the previously studied Z-disk of the honeybee Apis mellifera. At the corners of the unit cell are positioned trimers of paired antiparallel F-actins defining a large solvent channel, whereas at the trigonal positions are positioned F-actin trimers converging slowly towards their (+) ends defining a small solvent channel through the Z-disk. These near parallel F-actins terminate at different Z-heights within the Z-disk. The two types of solvent channel in Lethocerus are similar in size compared to those of Apis which are very different in size. Two types of α-actinin crosslinks were observed between oppositely oriented actin filaments. In one of these, the α-actinin long axis is almost parallel to the F-actins it crosslinks. In the other, the α-actinins are at a small but distinctive angle with respect to the crosslinked actin filaments. The utility of isolated Z-disks for structure determination is discussed.

Tensor tomography of the residual stress field in graded-index YAG’s single crystals

Abstract This work presents an application of tensor field tomography for non-destructive reconstructions of axially symmetric residual stresses in a graded-index YAG single crystal for the case of beam deflection. The axis of the cylinder coincides with the crystallographic axis [001] of the single crystal and it has an axially symmetric refractive index distribution. The transformation of the polarization of light is measured in a plane orthogonal to the axis of the cylinder. Stresses are determined within the framework of the Maxwell piezo-optic law (linear dependence of the permittivity tensor on stresses) and small rotation of quasi principal stress axes. This paper generalizes the method of integrated photoelasticity for the case of ray deflection.

Landslide Investigation through Emerging Technology of Electrical Resistivity Tomography

A landslide is an event of a disaster and has adverse effects on every country with varying degrees of impact. The lithology's complex nature, the vast slide area and the landslide's topography make the direct investigation challenging. In depth landslide investigation demands multidisciplinary knowledge, skilled human power and costly testing equipment, making direct investigation tedious and time-consuming. However, an alternative for the direct investigation is needed to cover all the aspects of landslide mechanism. Recently advanced geophysical methods have an excellent potential for collecting landslide mechanism-related information without disturbing them. One such method is effectively used to investigate the soil's subsurface properties as one of the significant threats to stability is rainfall in a landslide-prone area and its resolve is effectively called Electrical Resistivity Tomography (ERT). The present study endeavors to display cutting-edge research on the applications of Electrical Resistivity Tomography (ERT) in the field of landslide investigation. The foremost objective of the study is to present the outcomes of geophysical surveys conducted through ERT, which encompass 1D, 2D, 3D and time-lapse investigations. The study also highlights the advantages and limitations of these ERT investigations and identifies potential challenges that need to be addressed for the optimum utilization of ERT in future research.

Tissue turbulence and its effects on optical waves: A review

Tissue turbulence and the effects of tissue turbulence on the propagation of optical waves are reviewed. After the introduction of a survey on the reported research in this area, various topics are elaborated. These topics include the spectrum of tissue turbulence, propagation of light in the tissue, average intensity, beam spread that occur at the receiver plane in the tissue. Other entities examined are the signal to noise ratio (SNR), intensity correlation, beam wander, mutual coherence function and the spectral degree of coherence. Furthermore, spectral change, cross spectral density, spectral correlation function, scintillation, bit error rate (BER), coupling efficiency in tissue turbulence are investigated. The refractive index structure of tissues, imaging in the presence of turbulence in the tissue, scattering, absorption and polarization aspects in tissues are reported. Finally, optical coherence tomography applications in turbulent tissues are reviewed.

Application of Ultrasonic Tomography to detect defects in Concrete Structures

Concrete is a material widely used in civil construction for structural elements. Due to this, there is an increasing concern about the knowledge of its deterioration state and safety. This stimulates research for methods that allow the evaluation of finished structures. Through the application of Nondestructive Testing (NDT) methods, it is possible to proceed with an investigation of the concrete structures. The application of NDT can contribute to problems diagnosis and quality control of concrete structures. Ultrasound Tomography (UT) tests are an attractive and feasible research strategy. UT allows mapping of the internal section of the object from projections of the same. The tomography uses an antenna, which in turn utilizes a series of dry contact point transducers that emit shear waves into the concrete structures. From the data collected by the equipment, 3D images of the element's reflected interfaces are generated. The present study aims to detect different anomalies that can be found in reinforced concrete slabs, verifying the potential of ultrasonic tomography for the detection of these anomalies. The study was performed by the technical team of the Structural Tests and Materials Laboratory at the Federal University of Rio Grande do Sul (LEME / UFRGS).

Application of Cross-hole Seismic Tomography to Inferred Cavities Condition.

The construction of the Rajamandala hydroelectric power plant civil works has experienced critical problems that arise in the implementation process, with the occurrence of cracks cavities conditions in the headrace tunnel locations. We applied the cross-hole seismic tomography to detect important heterogeneities and mechanical proprieties of the formations between two boreholes in this case inferred cracks cavities condition. The seismic source is inside the borehole “a sparker” and the receivers “hydrophones” are in an adjacent one, the sparker is lowered into the borehole one step at the time. Seismic waves, propagating in the tunnel wall rock, spread widely, and are reflected and refracted when encountering interfaces between rocks with different acoustic impedances. Reflected waves returning to the receivers are recorded. After the processing of the first arrivals of the P waves we obtain a cross section of the seismic velocities in between the two wellbores. With the cross-hole seismic tomography, the basis could be provided to the tunnel construction and parameter adjustments to guarantee the construction safety. Our result shown that there is a weak zone above the tunnel with low Vp zone (~1.2 km/s) may be related to weak zone (may be fracture, unconsolidated rock, and fluid-filled rock or landslide caving). Checker-board resolution test is also conducted to determine the tomogram areas that are reliable to be interpreted. Our challenges are we have poor resolution due to not enough raypath. The Cross-hole seismic tomography can effectively and safely guide the excavation of the tunnel section working surface in combination with reconstructed images and excavation technology.

Insights into the Application of Ultrasound Tomography in the Precipitation of Calcium Carbonate

AbstractThe application of an ultrasound tomography (UST) system in a liquid‐phase reactive crystallization process is reported. The measurement system was applied to precipitated calcium carbonate processing where liquid Na2CO3 was added to a CaCl2 solution. Analysis of the measured sound velocity signals from the experiments demonstrated a clear change in the average time‐of‐flight (TOF) delay signals, indicating the detection of the onset of the precipitation and the formation of the microcrystalline stable phase of calcite. Moreover, spatial‐centric TOF signals from the tomographic images were associated with an increase in the overall suspension density. These findings highlight the potential of the UST measurement system for studying the solidification phenomenon during CaCO3 precipitation.

Application of fluorescence micro-optical sectioning tomography in the cerebrovasculature and applicable vascular labeling methods.

Fluorescence micro-optical sectioning tomography (fMOST) is a three-dimensional (3d) imaging method at the mesoscopic level. The whole-brain of mice can be imaged at a high resolution of 0.32 × 0.32 × 1.00 μm3. It is useful for revealing the fine morphology of intact organ tissue, even for positioning the single vessel connected with a complicated vascular network across different brain regions in the whole mouse brain. Featuring its 3d visualization of whole-brain cross-scale connections, fMOST has a vast potential to decipher brain function and diseases. This article begins with the background of fMOST technology including a widespread 3D imaging methods comparison and the basic technical principal illustration, followed by the application of fMOST in cerebrovascular research and relevant vascular labeling techniques applicable to different scenarios.

Application of Atom Probe Tomography to Study Corrosion of Nuclear Materials.

Application of Atom Probe Tomography to Study Corrosion of Nuclear Materials.

Applications of Soft X-ray Tomography for the Direct Observation of Native Cellular Events.

Applications of Soft X-ray Tomography for the Direct Observation of Native Cellular Events.

Automated Synthesis and Preclinical Evaluation of Optimized Integrin α6-Targeted Positron Emission Tomography Imaging of Pancreatic Cancer.

Integrin α6 has been considered a promising biomarker, is overexpressed in many tumors, and plays a vital role in tumor formation, recurrence, and metastasis. In this study, we identified a novel high-affinity integrin α6-targeted peptide named RD2 (Arg-Trp-Tyr-Asp-PEG4)2-Lys-Lys and developed a 18F-radiolabeled peptide tracer ([18F]-AlF-NOTA-RD2) and evaluated its potential application in positron emission tomography (PET) imaging of pancreatic cancer. [18F]-AlF-NOTA-RD2 was produced using GMP (Good Manufacturing Practice of Medical Products)-compliant automatic radiosynthesis on a single GE FASTLab2 cassette-type synthesis module. The stability of [18F]-AlF-NOTA-RD2 was analyzed in phosphate-buffered saline (PBS) and fetal bovine serum (FBS). The cell uptake assay of the tracer was assessed using PANC-1 cells. In addition, small-animal PET imaging and biodistribution studies of [18F]-AlF-NOTA-RD2 were performed in pancreatic cancer subcutaneous tumor-bearing mice. The PET tracer [18F]-AlF-NOTA-RD2 was obtained with a radiochemical yield of 23.7 ± 4.7%, radiochemical purity of >99%, and molar activity of 165.7 ± 59.1 GBq/μmol. [18F]-AlF-NOTA-RD2 exhibited good in vitro stability in PBS and FBS. LogP octanol water value for the tracer was -2.28 ± 0.05 (n = 3). The binding affinity of RD2 to the integrin α6 protein (Kd = 0.13 ± 3.65 μM, n = 3) was significantly higher than that of the RWY (CRWYDENAC) (Kd = 6.97 ± 1.44 μM, n = 3). Small-animal PET imaging and biodistribution also revealed that [18F]-AlF-NOTA-RD2 displayed rapid and good tumor uptake and lower liver background uptake in PANC-1 tumor-bearing mice. [18F]-AlF-NOTA-RD2 showed significant radioactivity accumulation in tumors and was successfully blocked by NOTA-RD2. Compared with [18F]-FDG, [18F]-AlF-NOTA-RD2 PET imaging and biodistribution studies in PANC-1 xenograft tumor-bearing mice confirmed a good tumor-to-muscle ratio (8.69 ± 2.03 vs 1.41 ± 0.23, respectively) at 0.5 h and (2.99 ± 3.02 vs 1.43 ± 0.17, respectively) at 1 h post injection. Autoradiography of human pancreatic cancer tumor tissues further confirmed high accumulation of [18F]-AlF-NOTA-RD2. In summary, we developed an optimized integrin α6-targeted imaging tracer and obtained high radioactivity products with a cassette-type synthesis module; moreover, the tracer exhibited good binding affinity with integrin α6 and good target specificity for PANC-1 cells in xenograft pancreatic tumor-bearing mice, demonstrating its promising application as a noninvasive PET radiotracer of integrin α6 expression in pancreatic cancer.

Objective quantification of posterior capsule opacification after cataract surgery with swept-source optical coherence tomography

PurposeTo evaluate the application of swept-source optical coherence tomography (SS-OCT) and pentacam scheimpflug tomography in posterior capsule opacification (PCO) severity assessment.MethodsThe posterior capsule image region segmentation and adaptive threshold algorithm are used to process the SS-OCT scanned image to obtain the posterior capsule thickness (PCT). Scheimpflug tomography reconstructed and analysized by image J software can obtain the average gray value and evaluate the effectiveness with the two methods.ResultOne hundred sixty-two IOL eyes of 101 patients were divided into two groups, laser group (65 eyes) with the mean PCT was 8.0 ± 2.7 pixel unit and the mean gray value of the eyes was 66 ± 33 pixel unit. However, these figures in the control group (97 eyes) were 5.0 ± 0.9 and 11 ± 17. The sensitivity, specificity and area under curve(AUC) of SS-OCT PCT were 85%, 74% and 0.942,the sensitivity, specificity and AUC of Pentacam gray value were 91%, 76% and 0.947, respectively. After using the multivariable model of generalized estimation equation to corrected the dependence of subjects' eyes, it was found that SS-OCT PCT, Pentacam gray value, low vision quality of life questionnaire (LVQ questionnaire) for distance vision, and mobility and lighting dimension were significantly correlated with the PCO score (P = 0.012, P = 0.001, P = 0.005, respectively).ConclusionThe region segmentation and adaptive threshold algorithm of posterior capsule image will accurately quantify the posterior capsule. Computer aided quantifications of posterior capsule are of great significance in the early surgical decision-making of PCO. The average occurrence time of most PCO was around 34 months, and the severity of PCO worsened with increasing postoperative time.

Application of electrical resistivity tomography (ERT) for vertical high-density polyethylene (HDPE) membrane detection

At landfill sites, uncontrolled leachate is a serious cause of groundwater and soil contamination at landfills and can occur extensively when there are looploopholesin the vertical HDPE (High-density polyethylene) membrane. For this reason, detecting HDPE membranes is necessary. The conventional electrode running poles approach is limited, it reflects the distribution of resistivity in 2D subsurface profiles, which is difficult to deploy electrodes above vertical HDPE membrane. According to the structural characteristics and field conditions of vertical HDPE membranes, the two-row current and potential (CP) electrode array is proposed to be applied to the testing of vertical HDPE membranes. The forward geoelectric model of the vulnerability was built using pyGimli, and data on 1519 apparent resistivity were acquired. The previous knowledge without the vulnerability was taken into consideration as the constraint condition, and the regional control was added to conduct the inversion, all using the least square approach. The model was used to analyze data on the detection of vertical HDPE membranes in a landfill In Yancheng, and potential flaws were discovered. Results show that the CP electrical measuring device can be efficient, quick, and accurate in the positioning of vertical HDPE membrane hole detection, and it is a cost-effective method. To verify the results, in the vertical HDPE membrane, through the Wenner device, the inversion of the 2D profile, and low resistivity anomalies are detected. This is thought to be through the leachate of leakage of HDPE membrane resistance rate is about 1.8 ohm. The findings demonstrate that the vertical HDPE membrane susceptibility may be located and detected using a CP electrical measuring instrument, which is a practical and efficient approach.

Electrical resistivity tomography technique coupled with numerical modelling: A case study for stability analysis

AbstractCavity due to underground old mine workings is one of the major threats to the coal mines and the overlying subsurface and surface properties, which need to be protected. The detection of old mine workings and stability assessment of overlying strata are common problems in most of the Indian coalfields. Several coal mines in India are loss‐making, mainly due to different types of mine hazards. Khandra mine is one such mine at Raniganj Coalfield, Eastern Coalfields Ltd., a subsidiary of Coal India Limited. In the present study, 2‐dimensional and 3‐dimensional electrical resistivity tomography were carried out for detailed subsurface characterization. It supports delineating underground workings, including the nature of voids/cavities (air or water‐filled). Excessive distortions were reported in electrical resistivity tomography application, especially at the near‐surface, owing to large resistivity variations. Refinement of the model by half‐unit electrode spacing was attempted here to reduce the distortions with minimum possible absolute errors. 3‐Dimensional resistivity volumetric model was also developed with the help of five electrical resistivity tomography parallel profiles for better apprehension of the subsurface. Analysis provided important inputs for stability analysis using 3‐dimensional numerical modelling. The physico‐mechanical properties of the overlying strata, pre‐excavation in situ stresses, boundary conditions and the mine geometry simulation were incorporated for understanding the stability analysis. Stability analysis was carried out using the finite difference technique. The analysis of 3‐dimensional numerical modelling indicated that two distinct layers comprising (i) laterite/part of the course to medium‐grained sandstone and (ii) developed galleries of R‐IX seam exhibited a very low safety factor below 1.0, indicating potholing/subsidence susceptibility. The other three layers comprising parts of fine‐grained sandstone exhibited a relatively higher safety factor of around 2.0, indicating moderately stable zones, but not on a long‐term basis. Parts of Siduli stream embankments need suitable retaining walls to avoid water inundation for the stability of the area.

P-295 Application of a Time-Lapse Optical Coherence Tomography (OCT) approach in a pilot study to visualise oocytes and embryos in depth

Abstract Study question Can we visualise model oocytes and embryos during embryo development using OCT non-invasively? Summary answer This approach, new to embryology, OCT, allows visualising cells in a 3D perspective, providing more detailed information than standard microscopy from the oocyte or embryo. What is known already Time-lapse is a well-established technique in human IVF, but it is limited in its depth of view due to the limitations of classical microscopy. To overcome this limitation, the approach of Optical Coherence Tomography (OCT), allows non-invasive visualisation through optical cross-sections of the embryo or oocyte to produce 3D images. The obtained information can be extended to 4 or 5 dimensions to track movement and elasticity, using a low-power light source and no staining to ensure the minimum effect on the cell. Here, a pilot study was performed in model (porcine) samples using a newly developed “in incubator” system. Study design, size, duration A pilot basic study was performed where 16 oocytes and 16 cleavage embryos were obtained and prepared to be visualised using OCT. Participants/materials, setting, methods Pig ovaries were obtained from a slaughterhouse, from which follicles were aspirated in order to retrieve oocytes. The best-quality oocytes were cultured for maturation for 44 hours and 16 oocytes were selected for OCT imaging. before fertilisation for 2 hours. Sperm was previously prepared by Percoll gradient. Zygotes were cultured for 6 days until visualisation through OCT. For imaging, samples were prepared in a 16-well Primo Vision dish. Main results and the role of chance Oocytes and embryos were successfully imaged, allowing the identification of distinct cellular features. In oocytes, it was possible to identify the germinal vesicle (nucleus) and polar bodies, individual blastomeres in cleavage stage embryos and trophectoderm, ICM and blastocoel in blastocysts. As images were taken throughout different optical sections, it was possible to correlate the position of the areas within the oocytes/embryos and create a 3D image from a blastocyst, understanding the size of the inner cell mass compared with the embryo's overall size. Interestingly, images were obtained non-invasively and under optimal conditions (in an incubator), demonstrating the future utility of OCT for embryo imaging. Limitations, reasons for caution An experimental OCT system was developed and placed in the incubator, and all images obtained were in a format of a pilot study. Future imaging sessions are planned to obtain more data points and assess the viability of the embryo. Wider implications of the findings Although in the present study, OCT was applied in pig oocytes and embryos, this new approach can be employed in future for human IVF to overcome the current imaging limitations, proving more information on the oocytes and embryos’ quality and assisting Artificial Intelligence analysis. Trial registration number not applicable

Seismic Waveform Tomography for 3D Impedance Model with Salt Structure

Conventional impedance inversion from post-stack zero-offset seismic data is usually based on the convolution model, and wave-equation based inversion is rarely used, although it is capable to precisely describe seismic wave propagation and invert impedance model with higher resolution. That is because there are more than one physical parameters involved in the conventional wave equation, making impedance inversion complicated. In this study, a one-dimensional (1D) wave equation, containing only the impedance parameter, is adopted and applied for the inversion of 1D impedance model by seismic waveform tomography. However, for a three-dimensional (3D) model, direct application of the 1D waveform tomography may lead to lateral discontinuities. Therefore, we propose to utilize a truncated Fourier series to parameterize the 3D impedance model, and then invert for the Fourier coefficients. With this parameterization scheme, the large- and small-scale components of the impedance model can be reconstructed stepwise by gradually increasing the number of Fourier coefficients. To efficiently and effectively invert the coefficients for the 3D model with salt structure, we propose a joint strategy, in which the low-frequency seismic data is used to invert for the Fourier coefficients representing the large-scale components of the model, while the high-frequency seismic data is applied to invert for the Fourier coefficients representing the small-scale components of the model. Tests on a 3D impedance model with salt structure result in models with high resolution and good spatial continuity, proving the feasibility and stability of the impedance inversion procedure.

Detection of recurrence sites using 18F-fluorocholine PET/CT in prostate cancer patients with PSA failure.

The optimal condition for the clinical application of 18F-fluorocholine positron emission tomography-computed tomography (FCH-PET/CT) to detect recurrence sites in prostate-specific antigen (PSA) failure remains unclear due to the heterogeneity of prostate cancer failure. We aimed to evaluate the detection rate of FCH-PET/CT in prostate cancer patients with PSA failure and to determine the optimal PSA level for performing FCH-PET/CT. FCH-PET/CT was conducted in 89 patients diagnosed with PSA failure after radical treatment (radical prostatectomy in 75 and definitive radiotherapy in 14) between November 2018 and May 2021. Detection rates were examined via receiver operating characteristic (ROC) analysis, and multivariable logistic regression was performed to identify factors affecting positive FCH-PET/CT findings. We also conducted subgroup analyses according to the PSA failure patterns after the radical treatment (persistently high PSA [N=48] and biochemical recurrence [BCR] [N=41]). FCH-PET/CT demonstrated a 59.6% overall detection rate, and the optimal PSA threshold for detecting positive findings was ≥ 1.00ng/mL at the time of imaging. On multivariable analysis, PSA > 1.00ng/mL (P<0.001) was a significant predictor of positive FCH-PET/CT findings, especially regarding distant bone metastases (P<0.001) and recurrence outside the pelvis (P<0.001). In a subgroup analysis of patients with BCR after initial radical treatment, the area under the ROC curve (AUC) was 0.82, and PSA ≥ 1.75ng/mL was the optimal value for identifying positive FCH-PET/CT findings. This PSA value was also associated with significantly higher detection rates of distant bone metastases and outside-pelvis metastasis (P<0.001, both). FCH-PET/CT is a clinically useful tool for detecting tumor recurrence sites in prostate cancer patients with PSA failure if PSA has exceeded a certain value at the time of imaging. Particularly, higher AUC values were observed when FCH-PET/CT was performed in patients with BCR after initial treatment.