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Articoli di riviste sul tema "Tomographic scanner"

Autore: Grafiati

Pubblicato: 5 aprile 2025

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1

Dao, Viet, Ekaterina Mikhaylova, Max L. Ahnen, Jannis Fischer, Kris Thielemans e Charalampos Tsoumpas. "Evaluation of STIR Library Adapted for PET Scanners with Non-Cylindrical Geometry". Journal of Imaging 8, n. 6 (18 giugno 2022): 172. http://dx.doi.org/10.3390/jimaging8060172.

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Software for Tomographic Image Reconstruction (STIR) is an open source C++ library used to reconstruct single photon emission tomography and positron emission tomography (PET) data. STIR has an experimental scanner geometry modelling feature to accurately model detector placement. In this study, we test and improve this new feature using several types of data: Monte Carlo simulations and measured phantom data acquired from a dedicated brain PET prototype scanner. The results show that the new geometry class applied to non-cylindrical PET scanners improved spatial resolution, uniformity, and image contrast. These are directly observed in the reconstructions of small features in the test quality phantom. Overall, we conclude that the revised “BlocksOnCylindrical” class will be a valuable addition to the next STIR software release with adjustments of existing features (Single Scatter Simulation, forward projection, attenuation corrections) to “BlocksOnCylindrical”.

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Karp, Joel S., Margaret E. Daube-Witherspoon e Gerd Muehllehner. "Factors Affecting Accuracy and Precision in PET Volume Imaging". Journal of Cerebral Blood Flow & Metabolism 11, n. 1_suppl (marzo 1991): A38—A44. http://dx.doi.org/10.1038/jcbfm.1991.35.

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Volume imaging positron emission tomographic (PET) scanners with no septa and a large axial acceptance angle offer several advantages over multiring PET scanners. A volume imaging scanner combines high sensitivity with fine axial sampling and spatial resolution. The fine axial sampling minimizes the partial volume effect, which affects the measured concentration of an object. Even if the size of an object is large compared to the slice spacing in a multiring scanner, significant variation in the concentration is measured as a function of the axial position of the object. With a volume imaging scanner, it is necessary to use a three-dimensional reconstruction algorithm in order to avoid variations in the axial resolution as a function of the distance from the center of the scanner. In addition, good energy resolution is needed in order to use a high energy threshold to reduce the coincident scattered radiation.

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Mangiorou, Eleni. "A Critical Assessment of the Four Basic Methods of Tomographic Imaging". Key Engineering Materials 605 (aprile 2014): 657–60. http://dx.doi.org/10.4028/www.scientific.net/kem.605.657.

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Τhe incidence of and mortality from cancer have been increasing steadily for the past 50 years. Most cancers are not localized when first detected, but early detection is mandatory to improve prognosis. In this article, we performed a comparison of four basic methods of tomographic imaging, Positron emission tomography (PET), the computerized tomography (CT), Magnetic Resonance Imaging (MRI) scanner and the ultrasound scanner (US), in respect to their advantages and disadvantages.

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Michail, Christos, George Karpetas, Nektarios Kalyvas, Ioannis Valais, Ioannis Kandarakis, Kyriakos Agavanakis, George Panayiotakis e George Fountos. "Information Capacity of Positron Emission Tomography Scanners". Crystals 8, n. 12 (9 dicembre 2018): 459. http://dx.doi.org/10.3390/cryst8120459.

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Background: The aim of the present study was to assess the upper information content bound of positron emission tomography (PET) images, by means of the information capacity (IC). Methods: The Geant4 Application for the Tomographic Emission (GATE) Monte Carlo (MC) package was used, and reconstructed images were obtained by using the software for tomographic image reconstruction (STIR). The case study for the assessment of the information content was the General Electric (GE) Discovery-ST PET scanner. A thin-film plane source aluminum (Al) foil, coated with a thin layer of silica and with a 18F-fludeoxyglucose (FDG) bath distribution of 1 MBq was used. The influence of the (a) maximum likelihood estimation-ordered subsets-maximum a posteriori probability-one step late (MLE-OS-MAP-OSL) algorithm, using various subsets (1 to 21) and iterations (1 to 20) and (b) different scintillating crystals on PET scanner’s performance, was examined. The study was focused on the noise equivalent quanta (NEQ) and on the single index IC. Images of configurations by using different crystals were obtained after the commonly used 2-dimensional filtered back projection (FBP2D), 3-dimensional filtered back projection re-projection (FPB3DRP) and the (MLE)-OS-MAP-OSL algorithms. Results: Results shown that the images obtained with one subset and various iterations provided maximum NEQ values, however with a steep drop-off after 0.045 cycles/mm. The single index IC data were maximized for the range of 8–20 iterations and three subsets. The PET scanner configuration incorporating lutetium orthoaluminate perovskite (LuAP) crystals provided the highest NEQ values in 2D FBP for spatial frequencies higher than 0.028 cycles/mm. Bismuth germanium oxide (BGO) shows clear dominance against all other examined crystals across the spatial frequency range, in both 3D FBP and OS-MAP-OSL. The particular PET scanner provided optimum IC values using FBP3DRP and BGO crystals (2.4829 bits/mm2). Conclusions: The upper bound of the image information content of PET scanners can be fully characterized and further improved by investigating the imaging chain components through MC methods.

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Izevbekhai, O. S., P. F. I. Irabor, S. U. Eluehike, B. Oriaifo e O. Otaigbe. "A Tally of Computed Tomographic Scan Findings in the Immediate Post-Installation Period in a Rural Based Hospital in Sub-Saharan Africa". Journal of Advances in Medicine and Medical Research 35, n. 20 (29 agosto 2023): 197–204. http://dx.doi.org/10.9734/jammr/2023/v35i205190.

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Background: The utilization of Computed Tomographic scanners for imaging has gradually evolved in Nigeria since the installation of the first scanner at the University College Hospital, Ibadan in 1989. However, most rural and sub-urban health facilities in Sub-Saharan Africa still lack this all-important modality. Aim and Objectives: To retrospectively determine the pattern of distribution of CT requests, indications and findings on imaging amongst a small cohort of patients scanned in the immediate post-installation phase of a 32-slice Canon CT scanner. Methods: We retrospectively reviewed the requests and reports of thirty patients who had undergone CT examinations of different body regions within the first ten days of installation of a 32-slice Aquilion CT scanner at the Radiology department of one of Nigerias’ leading infectious disease hospital (Irrua Specialist Teaching Hospital) in Irrua town. The data were retrieved, coded and entered into Microsoft excel spreadsheet and further analysed using SPSS version 21. Results: Male patients were more than females in an approximate ratio of 2:1. Majority of patients fell within the age range of 18-64 years. Stroke was the commonest indication and accounted for 33.3% of patients imaged. Although, the craniofacial region was the most commonly imaged region for suspected neurological diseases accounting for 20(67%) of patients, the brain was observed to be grossly normal in 7(23.3%) patients. Rhinosinusitis was the commonest finding seen. Conclusions: Males were the most commonly scanned group, while the craniofacial region was the most imaged region. Neurological disorders and stroke cases together accounted for most CT referrals with stroke being the commonest. Rhinosinusitis and normal brain morphology were the most commonly encountered findings.

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Shampo, Marc A., e Robert A. Kyle. "Allan Cormack—Codeveloper of Computed Tomographic Scanner". Mayo Clinic Proceedings 71, n. 3 (marzo 1996): 288. http://dx.doi.org/10.4065/71.3.288.

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7

TAGUCHI, Isamu. "Computerized tomographic scanner for iron and steel." Analytical Sciences 1, n. 1 (1985): 93–94. http://dx.doi.org/10.2116/analsci.1.93.

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8

Jofre, L., M. S. Hawley, A. Broquetas, E. de los Reyes, M. Ferrando e A. R. Elias-Fuste. "Medical imaging with a microwave tomographic scanner". IEEE Transactions on Biomedical Engineering 37, n. 3 (marzo 1990): 303–12. http://dx.doi.org/10.1109/10.52331.

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9

Abdelkarim, Ayman, Sion K. Roy, April Kinninger, Azadeh Salek, Olivia Baranski, Daniele Andreini, Gianluca Pontone et al. "Evaluation of Image Quality for High Heart Rates for Coronary Computed Tomographic Angiography with Advancement in CT Technology: The CONVERGE Registry". Journal of Cardiovascular Development and Disease 10, n. 9 (19 settembre 2023): 404. http://dx.doi.org/10.3390/jcdd10090404.

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Objective: This study aims to evaluate image quality in patients with heart rates above or equal to 70 beats per minute (bpm), performed on a 16 cm scanner (256-slice General Electric Revolution) in comparison to a CT scanner with only 4 cm of coverage (64 slice Volume CT). Background: Recent advancements in image acquisition, such as whole-heart coverage in a single rotation and post-processing methods in coronary computed tomographic angiography (CCTA), include motion-correction algorithms, such as SnapShot Freeze (SSF), which improve temporal resolution and allow for the assessment of coronary artery disease (CAD) with lower motion scores and better image qualities. Studies from the comprehensive evaluation of high temporal- and spatial-resolution cardiac CT using a wide coverage system (CONVERGE) registry (a multicenter registry at four centers) have shown the 16 cm CT scanner having a better image quality in comparison to the 4 cm scanner. However, these studies failed to include patients with undesirable or high heart rates due to well-documented poor image acquisition on prior generations of CCTA scanners. Methods: A prospective, observational, multicenter cohort study comparing image quality, quantitively and qualitatively, on scans performed on a 16 cm CCTA in comparison to a cohort of images captured on a 4 cm CCTA at four centers. Participants were recruited based on broad inclusion criteria, and each patient in the 16 cm CCTA arm of the study received a CCTA scan using a 256-slice, whole-heart, single-beat scanner. These patients were then matched by age, gender, and heart rate to patients who underwent CCTA scans on a 4 cm CT scanner. Image quality was graded based on the signal-to-noise ratio, contrast-to-noise ratio, and on a Likert scale of 0–4: 0, very poor—4, excellent. Results: 104 patients were evaluated for this study. The mean heart rate was 75 ± 7 in the 4 cm scanner and 75 ± 7 in the 16 cm one (p = 0.426). The signal-to-noise and contrast-to-noise ratios were higher in the 16 cm scanner (p = 0.0001). In addition, more scans were evaluated as having an excellent quality on the 16 cm scanner than on the 4 cm scanner (p < 0.0001) based on a 4-point Likert scale. Conclusions: The 16 cm scanner has a superior image quality for fast heart rates compared to the 4 cm scanner. This study shows that there is a significantly higher frequency of excellent and good studies showing better contrast-to-noise and signal-to-noise ratios with the 16 cm scanner compared to the 4 cm scanner.

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Chindasombatjaroen, Jira, Naoya Kakimoto, Hiroaki Shimamoto, Shumei Murakami e Souhei Furukawa. "Correlation Between Pixel Values in a Cone-Beam Computed Tomographic Scanner and the Computed Tomographic Values in a Multidetector Row Computed Tomographic Scanner". Journal of Computer Assisted Tomography 35, n. 5 (settembre 2011): 662–65. http://dx.doi.org/10.1097/rct.0b013e31822d9725.

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Michailidis, Georgios, Stavroula Kyriazi, Alicia Maravelia, Eleni Tourna, Constantinos M. Couvaris, Kiriakos Kalampoukas, Ioannis Pantazis et al. "Chronic maxillary atelectasis under the wrappings of an Egyptian mummy". Annals of Otology, Rhinology & Laryngology 128, n. 12 (30 settembre 2019): 1165–69. http://dx.doi.org/10.1177/0003489419879716.

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Objectives: In the context of a joint Mummy Research Project of the National Archaeological Museum, the Hellenic Institute of Egyptology and the Athens Medical Centre, an Egyptian mummy of the mid-Ptolemaic Period was transferred to our hospital and was thoroughly investigated with Computed Tomography. Methods: The mummy was carefully removed from its coffin and scanned in a 64-detector row computed tomographic scanner. Multiplanar and anthropometric measurements were obtained using advanced software. Results: The mummy appeared to be well-preserved and belonged to a young male adult. Among the findings, the most interesting and uncommon one was the asymmetry of the maxillary sinuses and the orbits. There were no signs of trauma. Conclusions: Computed Tomography revealed in a non-destructive way a rare, based on the published data, facial deformity in an Egyptian mummy attributed to chronic maxillary atelectasis.

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Zenari, A., R. H. Hooper, N. Osborne e J. W. Scrimger. "Iterative deblurring algorithm for a multiplane tomographic scanner". Physics in Medicine and Biology 30, n. 7 (1 luglio 1985): 657–68. http://dx.doi.org/10.1088/0031-9155/30/7/004.

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Batova, M. A. "The Role of Cone-Beam Computed Tomography in Diagnostics of Cystic Masses of the Jaw". Medical Visualization, n. 3 (28 giugno 2017): 14–19. http://dx.doi.org/10.24835/1607-0763-2017-3-14-19.

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Research objective. The study aimed to evaluate cone-beam computed tomography (CBCT) capabilities in diagnostics of cystic masses of the jaw.Methods. Over a period of 2015–2016 32 patients age 6 to 67 underwent both panoramic tomography and CBCT (using panoramic tomographic scanner STRATO 2000 and cone-beam computed tomographic scanner i-Cat respectively). 47% (n = 15) of the participants were women, 53% (n = 17) – men. Radiation exposure for a single procedure amounts to 0,05 mSv for panoramic tomography, 0,07 mSv for CBCT (FOV =13 cm), 0,06 mSv for CBCT (FOV =8 cm).Results. Comparative analysis of obtained results demonstrates that CBCT showed 54% (n = 27) more cystic masses of the jaws than panoramic radiography could. CBCT additionally showed the following pathologies: granulomas smaller than4 mm diameter – 85% (n = 23), 83% (n = 23) of said granulomas were found on maxilla, radicular cysts of maxilla – 11% (n = 3), incisive canal cyst – 4% (n = 1). Additionally panoramic tomography analysis misdiagnosed 5 granulomas (80% (n = 4) on mandibular premolar and molar areas) that were not found during CBCT analysis.Conclusion. The low effective dose and high informativity of CBCT enables the method to be used instead of intraoral radiography, panoramic tomography and MSCT as a screening procedure in diagnostics of dento-facial system pathologies, including cystic masses of the jaw.

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Coffey, Robert J., e William A. Friedman. "Interstitial Brachytherapy of Malignant Brain Tumors Using Computed Tomography-guided Stereotaxis and Available Imaging Software: Technical Report". Neurosurgery 20, n. 1 (1 gennaio 1987): 4–7. http://dx.doi.org/10.1227/00006123-198701000-00002.

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Abstract The implantation of radioactive sources into malignant intraaxial brain tumors, interstitial brachytherapy, is a theoretically attractive treatment for these nearly uniformly fatal lesions. Optimal application of this treatment modality requires careful preoperative planning, computer-assisted dosimetry, and computed tomography-guided stereotactic implantation of the isotope-bearing catheters. A method is presented by which available computed tomographic imaging software can be used with a standard radiotherapy treatment planning computer and the Brown-Roberts-Wells stereotactic system for preoperative imaging, dosimetry planning, and brachytherapy catheter insertion. Dedicated computer facilities are not required, making this method available to any neurosurgeon with access to a current generation computed tomographic scanner.

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Marahrens, P., B. Jean, A. Frohn, H. J. Thiel e G. Zinser. "Goniometry with the Laser Tomographic Scanner (LTS) in ECCE". European Journal of Implant and Refractive Surgery 4, n. 4 (dicembre 1992): 237–40. http://dx.doi.org/10.1016/s0955-3681(13)80466-2.

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Padhi, Shantanu, John Howard, A. Fhager e Sebastian Bengtsson. "A PC-controlled microwave tomographic scanner for breast imaging". Review of Scientific Instruments 82, n. 1 (gennaio 2011): 014702. http://dx.doi.org/10.1063/1.3523048.

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de Groot, J. A. M., E. H. Huizing, H. Damsma, F. W. Zonneveld e P. F. G. M. van Waes. "Labyrinthine Otosclerosis Studied with a New Computed Tomography Technique". Annals of Otology, Rhinology & Laryngology 94, n. 3 (maggio 1985): 223–25. http://dx.doi.org/10.1177/000348948509400301.

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Forty-two patients (84 ears) with surgically confirmed otosclerosis were examined with a computerized tomographic scanner (Philips Tomoscan 310) equipped with a table swivel mechanism. All ears were scanned in the horizontal and a new semilongitudinal plane. In patients with an unimpaired bone conduction threshold, a normal labyrinthine capsule was found in all ears except two. Normal bone conduction does not exclude extensive labyrinthine otospongiosis. In cases with bone conduction impairment, the bony labyrinth appeared normal in about half the ears. In the other half, areas of bone resorption were present and a positive correlation was found between the degree of bone loss and the amount of bone conduction threshold loss.

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Zioga, M., A. Nikopoulou, M. Alexandridi, D. Maintas, M. Mikeli, A. N. Rapsomanikis e E. Stiliaris. "Image Reconstruction in the Positron Emission Tomography". HNPS Proceedings 20 (1 dicembre 2012): 73. http://dx.doi.org/10.12681/hnps.2490.

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Positron Emission Tomography (PET) has become a valuable tool with a broad spectrum of clinical applications in nuclear imaging. PET scanners can collect in vivo information from positron radiotracer distributions, which is further recon- structed to a tomographic image with the help of well established analytical or iterative algorithms. In this current work, an innovative PET image reconstruction method from raw data based on a simple mathematical model is presented. The developed technique utilizes the accumulated density distribution in a predefined voxelized volume of interest. This distribution is calculated by intersecting and weighting the two-gamma annihilation line with the specified voxels. In order to test the efficiency of the new algorithm, GEANT4/GATE simulation studies were performed. In these studies, a cylindrical PET scanner was modeled and the photon interaction points are validated on an accurate physical basis. An appropriate cylin- drical phantom with different positron radiotracers was used and the reconstructed results were compared to the original phantom.

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Slocum, Alexander H., Stephen E. Jones e Rajiv Gupta. "Design of a Calibration Phantom for Measuring the Temporal Resolution of a Tomographic Imaging Device". Journal of Medical Devices 1, n. 3 (13 agosto 2007): 225–32. http://dx.doi.org/10.1115/1.2785189.

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This paper describes the design and development of a calibration phantom to be used to aid in the calculation of the temporal resolution of tomographic imaging devices. Current practice for characterizing the dynamic response of a tomographic imaging device, such as a computed tomography or magnetic resonance imaging machine, uses image acquisition time as a surrogate for temporal resolution. At present, no standard method for describing the temporal resolution of a tomographic imaging device exists. Similar to the spatial modulation transfer function (MTF) used for characterizing spatial resolution, the concept of temporal MTF (t-MTF) can be used to enable characterization of temporal resolution. A scanner’s t-MTF represents the percentage amplitude modulation transfer in the image as a function of the input frequency. The calibration phantom uses slotted disks, each mounted to the rotating ring gear of a planetary gear assembly. The sun gears of each planetary gear set are driven from a common shaft to create differential speed sectors, allowing for about two decades of input frequencies to be obtained using a single motor and driveshaft. Preliminary results show a monotonic decline in the modulation transfer as the input frequency is increased. As expected, there is more modulation transfer at lower frequency and less modulation transfer at high frequency. Analogous to the spatial resolution, one can define the frequency for which there is 10% modulation transfer as the temporal resolution of a scanner.

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Dreher, Andreas W., Josef F. Bille e Robert N. Weinreb. "Active optical depth resolution improvement of the laser tomographic scanner". Applied Optics 28, n. 4 (15 febbraio 1989): 804. http://dx.doi.org/10.1364/ao.28.000804.

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Okudera, H., S. Kobayashi, K. Kyoshima, H. Gibo, T. Takemae e K. Sugita. "Development of the operating computerized tomographic scanner system for neurosurgery". Acta Neurochirurgica 111, n. 1-2 (marzo 1991): 61–63. http://dx.doi.org/10.1007/bf01402515.

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Yamada, Akira, Kensuke Sasaki e Toshihiko Yokoyama. "Body surface scanner for the abdominal sound speed tomographic imaging". Journal of the Acoustical Society of America 131, n. 4 (aprile 2012): 3363. http://dx.doi.org/10.1121/1.4708676.

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TAGUCHI, Isamu, e Shigeo NAKAMURA. "Development of X-ray Computed Tomographic Scanner for Iron and Steel". Tetsu-to-Hagane 71, n. 14 (1985): 1685–91. http://dx.doi.org/10.2355/tetsutohagane1955.71.14_1685.

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Pérez-Sánchez, Guillermo, Maykel González-Torres, Mario Guzmán-Espinosa, Víctor Hernández-Vidal, Bernardo Teutle-Coyotecatl, Luz Mendoza-García e Angeles Moyaho-Bernal. "Vestibular Alveolar bone height measurement: Accuracy and Correlation between direct and indirect techniques." Acta Odontológica Latinoamericana 33, n. 1 (giugno 2020): 22–26. http://dx.doi.org/10.54589/aol.33/1/022.

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Cone Beam Computed Tomography (CBCT) has modified the perspective of dentistry images, providing manipulable threedimensional images with a 1:1 patient:image ratio. Treatments and diagnosis are modified or corroborated by CBCT; however, its accuracy in thin structures such as cortical bone has been subjected to critical review. The aim of this study is to correlate the measurement of vestibular alveolar bone height using direct measurements and measurements performed with cone-beam tomographic images with standard (SD) voxel resolution. Thirty incisor and premolar teeth of patients undergoing open curettage were measured with a high-precision caliper and with Cone Beam Computed Tomography (CBCT) at an SD resolution of 0.16 mm voxels in a 3D Orthophos XG Sirona scanner. Intra-observer evaluation was performed using the intraclass correlation coefficient (ICC). Direct measurements and CBCT measurements were correlated using Pearson correlation (PCC). The mean difference between indirect and direct measurements was 3.15 mm. Paired t test and Pearson Correlation coefficient determined that all measurements differed statistically from each other with p<0.05. With the CT scanner and protocol used in this study, CBCT images do not enable accurate evaluation of vestibular alveolar bone height

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Kersemans, Veerle, Stuart Gilchrist, Philip Danny Allen, Sheena Wallington, Paul Kinchesh, John Prentice, Martin Tweedie, Jamie H. Warner e Sean C. Smart. "A System-Agnostic, Adaptable and Extensible Animal Support Cradle System for Cardio-Respiratory-Synchronised, and Other, Multi-Modal Imaging of Small Animals". Tomography 7, n. 1 (7 febbraio 2021): 39–54. http://dx.doi.org/10.3390/tomography7010004.

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Standardisation of animal handling procedures for a wide range of preclinical imaging scanners will improve imaging performance and reproducibility of scientific data. Whilst there has been significant effort in defining how well scanners should operate and how in vivo experimentation should be practised, there is little detail on how to achieve optimal scanner performance with best practices in animal welfare. Here, we describe a system-agnostic, adaptable and extensible animal support cradle system for cardio-respiratory-synchronised, and other, multi-modal imaging of small animals. The animal support cradle can be adapted on a per application basis and features integrated tubing for anaesthetic and tracer delivery, an electrically driven rectal temperature maintenance system and respiratory and cardiac monitoring. Through a combination of careful material and device selection, we have described an approach that allows animals to be transferred whilst under general anaesthesia between any of the tomographic scanners we currently or have previously operated. The set-up is minimally invasive, cheap and easy to implement and for multi-modal, multi-vendor imaging of small animals.

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Ladas, K. T., e A. J. Devaney. "Application of An Art Algorithm in an Experimental Study of Ultrasonic Diffraction Tomography". Ultrasonic Imaging 15, n. 1 (gennaio 1993): 48–58. http://dx.doi.org/10.1177/016173469301500105.

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This paper describes results obtained using a recently developed Algebraic Reconstruction Technique (ART) for diffraction tomography on experimental data obtained from an ultrasound scanner built by Norwave Development A.S. of Oslo, Norway. The test objects (phantoms) employed in the study are low contrast cylindrical rods made out of agar with dimensions comparable to the wavelength of the incident wavefield. The reconstructions obtained from the ART algorithm are compared to the ones obtained from the filtered backpropagation algorithm. It is determined that the ART algorithm out performs the filtered backpropagation algorithm for cases where data from only a small number of tomographic experiments are available.

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Shakya, Snehlata, e Prabhat Munshi. "Error analysis of tomographic reconstructions in the absence of projection data". Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 373, n. 2043 (13 giugno 2015): 20140394. http://dx.doi.org/10.1098/rsta.2014.0394.

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Error estimates for tomographic reconstructions (using Fourier transform-based algorithm) are available for cases where projection data are available. These data are used for reconstructions with different filter functions and the reliability of these reconstructions can be checked as per guidelines of those error estimates. There are cases where projection data are large (in gigabytes or terabytes) so storage of these data becomes an issue. It leads to storing of only the reconstructed images. Error estimation in such cases is presented here. Second-level projection data are calculated from the given reconstructed images (‘first-level’ images). These ‘second-level’ data are now used to generate ‘second-level’ reconstructed images. Different filter functions are employed to check the fidelity of these ‘second-level’ images. This inference is extended to first-level images in view of the characteristics of the convolution operator. This approach is validated with experimental data obtained by the X-ray micro-CT scanner installed at IIT Kanpur. Five specimens (of same material) have been scanned. Data are available in this case thus we have performed a comparative error estimate analysis for the ‘first-level’ reconstructions (data obtained from CT machine) and second-level reconstructions (data generated from first-level reconstructions). We observe that both approaches show similar outcome. It indicates that error estimates can also be applied to images when data are not available.

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Müller, Martin, Gonzalo R. Arce e Robert A. Blake. "Synthetic scanner arrays in tomographic reconstructions from fan- and cone-beam projections". Applied Optics 33, n. 35 (10 dicembre 1994): 8255. http://dx.doi.org/10.1364/ao.33.008255.

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Butler, William E., Cristina M. Piaggio, Christodoulos Constantinou, Loren Niklason, R. Gilberto Gonzalez, G. Rees Cosgrove e Nicholas T. Zervas. "A Mobile Computed Tomographic Scanner with Intraoperative and Intensive Care Unit Applications". Neurosurgery 42, n. 6 (1 giugno 1998): 1304–10. http://dx.doi.org/10.1097/00006123-199806000-00064.

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Lunsford, L. Dade. "A Mobile Computed Tomographic Scanner with Intraoperative and Intensive Care Unit Applications". Neurosurgery 42, n. 6 (1 giugno 1998): 1310. http://dx.doi.org/10.1097/00006123-199806000-00065.

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Batjer, H. Hunt. "A Mobile Computed Tomographic Scanner with Intraoperative and Intensive Care Unit Applications". Neurosurgery 42, n. 6 (1 giugno 1998): 1310–11. http://dx.doi.org/10.1097/00006123-199806000-00066.

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Fahlbusch, Rudolf. "A Mobile Computed Tomographic Scanner with Intraoperative and Intensive Care Unit Applications". Neurosurgery 42, n. 6 (1 giugno 1998): 1311. http://dx.doi.org/10.1097/00006123-199806000-00067.

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Chandler, William F. "A Mobile Computed Tomographic Scanner with Intraoperative and Intensive Care Unit Applications". Neurosurgery 42, n. 6 (1 giugno 1998): 1311. http://dx.doi.org/10.1097/00006123-199806000-00068.

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34

E. W. Tollner, R. Harrison e C. Murphy. "NTERPRETING THE PIXEL STANDARD DEVIATION STATISTIC FROM AN X-RAY TOMOGRAPHIC SCANNER". Transactions of the ASAE 34, n. 3 (1991): 1054–59. http://dx.doi.org/10.13031/2013.31770.

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35

Weinreb, Robert N., Andreas W. Dreher e Josef F. Bille. "Quantitative assessment of the optic nerve head with the laser tomographic scanner". International Ophthalmology 13, n. 1-2 (gennaio 1989): 25–29. http://dx.doi.org/10.1007/bf02028633.

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36

Dwivedi, Abhishek, Ankur Sharma, Rachit Sharma, Prateek Awasthi e Satveer Singh Choudhary. "Utility of Pulmonary Angiography by 128-Slice Computed Tomographic Scanner in Diagnosis of Tetralogy of Fallot Cases". Case Reports in Radiology 2024 (9 maggio 2024): 1–6. http://dx.doi.org/10.1155/2024/3543906.

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Abstract (sommario):

Tetralogy of Fallot (TOF) is a significant cause of cyanotic congenital heart disease (CHD) encountered in childhood with few cases manifesting in adulthood. It has four classical features (ventricular septal defect, overriding of aorta, hypertrophy of right ventricular hypertrophy, and right ventricular outflow tract obstruction), but the clinical presentation and course can be variable. Due to various anatomical variations and complex anatomy, presurgical planning and postoperative follow-up by pulmonary computed tomographic angiography (CTA) have a very important role. With continued technological advances and the availability of 128-slice computed tomographic (CT) scans, they now play an important role in TOF preoperative evaluation and workup, assisting by minimizing routine invasive digital subtraction catheter angiography. The fast scan of a 128-slice CTA with very sensitive detectors is a very useful modality for studying the complex anatomy and variations as well as its utilization for postoperative management. In this article, we report four cases of TOF where we used a 128-slice scan for performing pulmonary angiography (Optima 660, GE 128, 2180 Premier Row, Orlando, FL 32809, U.S.A.) for preoperative diagnosis and management of three cases and work up for revision surgery for an already operated case with a nonfunctional modified Blalock-Taussig shunt with additional lung parenchymal findings simultaneously. This study will explain the advantageous role of the 128-slice CT scanner over the lesser-slice CT scanners with the ability of pulmonary CTA to facilitate accurate diagnosis and postoperative management.

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Mao, Song S., Raveen S. Pal, Charles R. McKay, Yan G. Gao, Ambarish Gopal, Naser Ahmadi, Janis Child et al. "Comparison of Coronary Artery Calcium Scores Between Electron Beam Computed Tomography and 64-Multidetector Computed Tomographic Scanner". Journal of Computer Assisted Tomography 33, n. 2 (marzo 2009): 175–78. http://dx.doi.org/10.1097/rct.0b013e31817579ee.

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38

Ahmedbacha, M. R., A. Benouar, A. Khorsi, N. Akermi e K. Kaddouri. "Simulation of Tomographic Acquisition and Reconstruction Slice for Industrial Machine Rotor with Fixed-Angle Scanner". Materials Evaluation 80, n. 8 (1 agosto 2022): 38–44. http://dx.doi.org/10.32548/2022.me-04263.

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Abstract (sommario):

Rotating machines such as electric motors and pumps are the heart of any industrial production chain. Rotors are usually the most worn parts, and the preventive maintenance of these vital organs, although necessary, remains penalizing for the production line because the machines are stopped and disassembled for a lengthy period during the inspection phase. This paper suggests a simulation of optimized tomographic reconstruction by cone beam acquisition geometry to scan a functioning machine rotor with high X-ray energy. In this work we propose a simple design of a fixed-angle projection scanner. Rotating projections are replaced by synchro-rotation to the nominal angular velocity of the rotor. The simulation results demonstrate that it is possible to adapt the filtered back-projection algorithm to compute a tomographic image of the rotor by a single projection device.

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Harada, Yosuke, Tomoyuki Akita, Joji Takenaka, Yuko Nakamura-Kadohiro, Junko Tanaka e Yoshiaki Kiuchi. "Reproducibility of optic disk evaluation in supine subjects with a Heidelberg Retina Tomograph II laser tomographic scanner". Clinical Ophthalmology Volume 10 (agosto 2016): 1617–22. http://dx.doi.org/10.2147/opth.s111250.

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40

Bakenecker, Anna C., Carlos Chinchilla e Thorsten M. Buzug. "Actuation of a magnetically coated swimmer in viscous media with a magnetic particle imaging scanner". Current Directions in Biomedical Engineering 6, n. 3 (1 settembre 2020): 349–52. http://dx.doi.org/10.1515/cdbme-2020-3090.

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Abstract (sommario):

AbstractMagnetic actuation of medical devices is of great interest in improving minimally invasive surgery and enabling targeted drug delivery. With untethered, magnetically coated swimmers it is aimed at reaching regions of the body difficult to access with catheters. Such a swimmer was previously presented, which is suitable for the navigation by the magnetic fields of a magnetic particle imaging (MPI) scanner. The swimmer could be imaged with MPI as well, enabling the tomographic real-time tracking of the actuation process. In this work the steerability of the swimmer is further investigated in media of varying viscosities. For this, glycerol-water-mixtures of different mixing ratios were used. The velocities of the swimmer were measured for viscosities between those of pure glycerol and pure water. The experiments were performed with an MPI scanner at maximal magnetic field strength of the actuating fields. A viscosity range was found in which the swimmer is steerable by the fields of an MPI scanner, which leads to a prediction of the applicability of the swimmer in different body fluids.

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Velu, Juliëtte F., Erik Groot Jebbink, Jean-Paul PM de Vries, Job AM van der Palen, Cornelis H. Slump e Robert H. Geelkerken. "A phantom study for the comparison of different brands of computed tomography scanners and software packages for endovascular aneurysm repair sizing and planning". Vascular 26, n. 2 (18 agosto 2017): 198–202. http://dx.doi.org/10.1177/1708538117726648.

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Abstract (sommario):

Objectives Correct sizing of endoprostheses used for the treatment of abdominal aortic aneurysms is important to prevent endoleaks and migration. Sizing requires several steps and each step introduces a possible sizing error. The goal of this study was to investigate the magnitude of these errors compared to the golden standard: a vessel phantom. This study focuses on the errors in sizing with three different brands of computed tomography angiography scanners in combination with three reconstruction software packages. Methods Three phantoms with a different diameter, altitude and azimuth were scanned with three computed tomography scanners: Toshiba Aquilion 64-slice, Philips Brilliance iCT 256-slice and Siemens Somatom Sensation 64-slice. The phantom diameters were determined in the stretched view after central lumen line reconstruction by three observers using Simbionix PROcedure Rehearsal Studio, 3mensio and TeraRecon planning software. The observers, all novices in sizing endoprostheses using planning software, measured 108 slices each. Two senior vascular surgeons set the tolerated error margin of sizing on ±1.0 mm. Results In total, 11.3% of the measurements (73/648) were outside the set margins of ±1.0 mm from the phantom diameter, with significant differences between the scanner types (14.8%, 12.1%, 6.9% for the Siemens scanner, Philips scanner and Toshiba scanner, respectively, p-value = 0.032), but not between the software packages (8.3%, 11.1%, 14.4%, p-value = 0.141) or the observers (10.6%, 9.7%, 13.4%, p-value = 0.448). Conclusions It can be concluded that the errors in sizing were independent of the used software packages, but the phantoms scanned with Siemens scanner were significantly more measured incorrectly than the phantoms scanned with the Toshiba scanner. Consequently, awareness on the type of computed tomography scanner and computed tomography scanner setting is necessary, especially in complex abdominal aortic aneurysms sizing for fenestrated or branched endovascular aneurysm repair if appropriate the sizing is of upmost importance.

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Jahan, WA, A. Azam, S. Deena, W. Begum e M. Rahman. "Safety, Efficacy and Indications of ?-Blockers to Reduce Heart Rate prior to Coronary CT Angiography-An Overview". Cardiovascular Journal 5, n. 1 (19 ottobre 2012): 100–106. http://dx.doi.org/10.3329/cardio.v5i1.12280.

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Abstract (sommario):

For selected indications, coronary computed tomographic (CT) angiography is an established clinical technology for evaluation in patients suspected of having or known to have coronary artery disease. In coronary CT angiography, image quality is highly dependent on heart rate, with heart rate reduction to less than 60 beats per minute being important for both image quality and radiation dose reduction, especially when single-source CT scanners are used. â-Blockers are the first-line option for short-term reduction of heart rate prior to coronary CT angiography. In recent years, multiple âblocker administration protocols with oral and/or intravenous application have been proposed.This review article provides an overview of the indications, efficacy, and safety of â-blockade protocols prior to coronary CT angiography with respect to different scanner techniques. Moreover,implications for radiation exposure and left ventricular function analysis are discussed DOI: http://dx.doi.org/10.3329/cardio.v5i1.12280 Cardiovasc. j. 2012; 5(1): 100-106

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Chmeissani, Mokhtar, Machiel Kolstein, Gerard Ariño-Estrada, José Gabriel Macias-Montero, Carles Puigdengoles e Jorge García. "Tracking a moving point source using triple gamma imaging". Journal of Instrumentation 19, n. 01 (1 gennaio 2024): P01001. http://dx.doi.org/10.1088/1748-0221/19/01/p01001.

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Abstract With positron emission tomography (PET), the positron of a β + emitter radioisotope annihilates with a nearby electron producing a pair of back-to-back 511 keV gamma rays that can be detected in a scanner surrounding the point source. The position of the point source is somewhere along the Line of Response (LOR) that passes through the positions where the 511 keV gammas are detected. In standard PET, an image reconstruction algorithm is used to combine these LORs into a final image. This paper presents a new tomographic imaging technique to locate the position of a β + emitting point source without using a standard PET image reconstruction algorithm. The data were collected with a Proof-of-Concept (PoC) PET scanner which has high spatial and energy resolutions. The imaging technique presented in this paper uses events where a gamma undergoes Compton scattering. The positions and energies deposited by the Compton scattered gamma define the surface of a Compton cone (CC) which is the locus of all possible positions of the point source, allowed by the Compton kinematics. The position of the same point source is also located somewhere on the LOR. Therefore, the position of the point source is defined by the 3 gammas and is given by the intersection point of the LOR and the Compton cone inside the Field of View (FOV) of the scanner. We refer to this method as CC×LOR. This new technique can locate the point source with an uncertainty of about 1 mm, after collecting a minimum of 200 CC×LOR events.

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Top, Can Baris, e Alper Gungor. "Tomographic Field Free Line Magnetic Particle Imaging With an Open-Sided Scanner Configuration". IEEE Transactions on Medical Imaging 39, n. 12 (dicembre 2020): 4164–73. http://dx.doi.org/10.1109/tmi.2020.3014197.

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45

Stuchebrov, S. G., A. V. Batranin e I. A. Miloichikova. "Modernization of the X-Ray Tomographic Scanner Based on Gas-Discharge Linear Detector". Journal of Physics: Conference Series 671 (18 gennaio 2016): 012004. http://dx.doi.org/10.1088/1742-6596/671/1/012004.

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46

FRIEDMAN, A., D. P. GROTE, C. M. CELATA e J. W. STAPLES. "Use of projectional phase space data to infer a 4D particle distribution". Laser and Particle Beams 21, n. 1 (gennaio 2003): 17–20. http://dx.doi.org/10.1017/s0263034602211040.

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Abstract (sommario):

We consider beams that are described by a four-dimensional (4D) transverse distribution f (x, y, x′, y′), where x′ ≡ px /pz and z is the axial coordinate. A two-slit scanner is commonly employed to measure, over a sequence of shots, a two-dimensional (2D) projection of such a beam's phase space, for example, f (x, x′). Another scanner might yield f (y, y′) or, using crossed slits, f (x, y). A small set of such 2D scans does not uniquely specify f (x, y, x′, y′). We have developed “tomographic” techniques to synthesize a “reasonable” set of particles in a 4D phase space having 2D densities consistent with the experimental data. We briefly summarize one method and describe progress in validating it, using simulations of the High Current Experiment at Lawrence Berkeley National Laboratory.

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47

Turkvatan, Aysel, Hasan Tahsin Tola, Pelin Ayyildiz, Erkut Ozturk, Yakup Ergul e Alper Guzeltas. "Total Anomalous Pulmonary Venous Connection in Children: Preoperative Evaluation with Low-Dose Multidetector Computed Tomographic Angiography". Texas Heart Institute Journal 44, n. 2 (1 aprile 2017): 120–26. http://dx.doi.org/10.14503/thij-15-5725.

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Abstract (sommario):

We report the results of our retrospective evaluation, from February 2011 through August 2014, of the anatomic features of total anomalous pulmonary venous connection (TAPVC) and its associated cardiovascular anomalies in a pediatric population. In all 43 patients under study (23 female; average age, 9 mo [range, 4 d–7.1 yr]), these examinations had been performed with a dual-source 256-detector scanner. The type of TAPVC, the presence of obstruction, and the association with other cardiovascular anomalies were investigated and recorded. In accordance with the absence or presence of these accompanying anomalies, patients were subdivided into 2 groups: isolated and complex. In the 43 patients, 22 (51%) TAPVCs were supracardiac, 10 (23%) were cardiac, 6 (14%) were infracardiac, and 5 (12%) were mixed. Obstruction was detected in 7 patients. Seventeen patients were in the isolated group and 26 in the complex group. The diagnostic agreements between multidetector computed tomographic angiographic and surgical results were 100% in both the isolated and complex groups. The overall average effective radiation dose was 0.66 mSv (range, 0.15–1.11 mSv); and it was 0.52 mSv (range, 0.12–0.72 mSv) in patients younger than 1 year of age. We conclude that computed tomographic angiography with a dual-source 256-slice multidetector scanner is a reliable imaging method that enables, despite lower radiation doses, the detailed and comprehensive anatomic imaging of TAPVC in neonates and children.

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48

Malhotra, Anmol, Sophia Tincey, Vishnu Naidu, Carla Papagiorcopulo, Debashis Ghosh, Peng H. Tan, Fred Wickham e Thomas Wagner. "Characterisation of MRI Indeterminate Breast Lesions Using Dedicated Breast PET and Prone FDG PET-CT in Patients with Breast Cancer—A Proof-of-Concept Study". Journal of Personalized Medicine 10, n. 4 (25 settembre 2020): 148. http://dx.doi.org/10.3390/jpm10040148.

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Abstract (sommario):

Magnetic resonance imaging (MRI) in patients with breast cancer to assess extent of disease or multifocal disease can demonstrate indeterminate lesions requiring second-look ultrasound and ultrasound or MRI-guided biopsies. Prone positron emission tomography-computed tomography (PET-CT) is a dedicated acquisition performed with a breast-supporting device on a standard PET-CT scanner. The MAMmography with Molecular Imaging (MAMMI, Oncovision, Valencia, Spain) PET system (PET-MAMMI) is a true tomographic ring scanner for the breast. We investigated if PET-MAMMI and prone PET-CT were able to characterise these MRI- indeterminate lesions further. A total of 10 patients with breast cancer and indeterminate lesions on breast MRI were included. Patients underwent prone PET-MAMMI and prone PET-CT after injection of FDG subsequently on the same day. Patients then resumed their normal pathway, with the clinicians blinded to the results of the PET-MAMMI and prone PET-CT. Of the MRI-indeterminate lesions, eight were histopathologically proven to be malignant and two were benign. PET-MAMMI and prone PET-CT only were able to demonstrate increased FDG uptake in 1/8 and 0/8 of the MRI-indeterminate malignant lesions, respectively. Of the MRI-indeterminate benign lesions, both PET-MAMMI and prone PET-CT demonstrated avidity in 1/2 of these lesions. Our findings do not support the use of PET-MAMMI to characterise indeterminate breast MRI lesions requiring a second look ultrasound.

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Perin, Rayhaan, Katie Cole, Michael R. van Heerden, Andy Buffler, Yi-Yu Lin, Jiahao Zhang, Pablo R. Brito-Parada, Jonathan Shock e Stephen W. Peterson. "On the Ability of Positron Emission Particle Tracking (PEPT) to Track Turbulent Flow Paths with Monte Carlo Simulations in GATE". Applied Sciences 13, n. 11 (31 maggio 2023): 6690. http://dx.doi.org/10.3390/app13116690.

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Abstract (sommario):

Positron emission particle tracking (PEPT) has offered important insights into the internal dynamics of multiphase flows. High precision and frequency measurements of the location of the tracer particle are required to resolve individual eddies at the millimetre scale or smaller. To explore the potential of PEPT to perform these measurements, a model was developed of the Siemens ECAT “EXACT3D” HR++ positron emission tomography (PET) scanner at the PEPT Cape Town facility in South Africa with the software Geant4 Application for Tomographic Emission (GATE) and was used to generate Lagrangian tracks from simulations of moving tracer particles. The model was validated with measurements from both experiment and simulation and was extended to two virtual scenarios inspired by turbulent flows. The location data from the simulation accurately captured linear portions of an oscillating path up to high speeds of 25 m s−1; however, tracking tended to undercut the turning points due to the high tracer acceleration. For a particle moving on a spiral path of decreasing radius, the location data tracked the path above a radius of 2.0 mm with an uncertainty equivalent to the radius of the tracer particle, 300 μm. Improvements to the measurement are required to track sub-millimetre flow structures, such as the application of PET scanners with higher spatial resolution and upgrades to the sampling processes used in location algorithms.

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Aouali, Abderezak, Stéphane Chevalier, Alain Sommier e Christophe Pradere. "Terahertz Constant Velocity Flying Spot for 3D Tomographic Imaging". Journal of Imaging 9, n. 6 (31 maggio 2023): 112. http://dx.doi.org/10.3390/jimaging9060112.

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Abstract (sommario):

This work reports on a terahertz tomography technique using constant velocity flying spot scanning as illumination. This technique is essentially based on the combination of a hyperspectral thermoconverter and an infrared camera used as a sensor, a source of terahertz radiation held on a translation scanner, and a vial of hydroalcoholic gel used as a sample and mounted on a rotating stage for the measurement of its absorbance at several angular positions. From the projections made in 2.5 h and expressed in terms of sinograms, the 3D volume of the absorption coefficient of the vial is reconstructed by a back-projection method based on the inverse Radon transform. This result confirms that this technique is usable on samples of complex and nonaxisymmetric shapes; moreover, it allows 3D qualitative chemical information with a possible phase separation in the terahertz spectral range to be obtained in heterogeneous and complex semitransparent media.

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