Artigos de revistas: "3-Gamma imaging"

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Haefner, Andrew, Ross Barnowski, Paul Luke, Mark Amman e Kai Vetter. "Handheld real-time volumetric 3-D gamma-ray imaging". Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 857 (junho de 2017): 42–49. http://dx.doi.org/10.1016/j.nima.2016.11.046.

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Vetter, Kai, Ross Barnowksi, Andrew Haefner, Tenzing H. Y. Joshi, Ryan Pavlovsky e Brian J. Quiter. "Gamma-Ray imaging for nuclear security and safety: Towards 3-D gamma-ray vision". Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 878 (janeiro de 2018): 159–68. http://dx.doi.org/10.1016/j.nima.2017.08.040.

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Hu, Yifan, Zhenlei Lyu, Peng Fan, Tianpeng Xu, Shi Wang, Yaqiang Liu e Tianyu Ma. "A Wide Energy Range and 4π-View Gamma Camera with Interspaced Position-Sensitive Scintillator Array and Embedded Heavy Metal Bars". Sensors 23, n.º 2 (13 de janeiro de 2023): 953. http://dx.doi.org/10.3390/s23020953.

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(1) Background: Gamma cameras have wide applications in industry, including nuclear power plant monitoring, emergency response, and homeland security. The desirable properties of a gamma camera include small weight, good resolution, large field of view (FOV), and wide imageable source energy range. Compton cameras can have a 4π FOV but have limited sensitivity at low energy. Coded-aperture gamma cameras are operatable at a wide photon energy range but typically have a limited FOV and increased weight due to the thick heavy metal collimators and shielding. In our lab, we previously proposed a 4π-view gamma imaging approach with a 3D position-sensitive detector, with which each detector element acts as the collimator for other detector elements. We presented promising imaging performance for 99mTc, 18F, and 137Cs sources. However, the imaging performance for middle- and high-energy sources requires further improvement. (2) Methods: In this study, we present a new gamma camera design to achieve satisfactory imaging performance in a wide gamma energy range. The proposed gamma camera consists of interspaced bar-shaped GAGG (Ce) crystals and tungsten absorbers. The metal bars enhance collimation for high-energy gamma photons without sacrificing the FOV. We assembled a gamma camera prototype and conducted experiments to evaluate the gamma camera’s performance for imaging 57Co, 137Cs, and 60Co point sources. (3) Results: Results show that the proposed gamma camera achieves a positioning accuracy of <3° for all gamma energies. It can clearly resolve two 137Cs point sources with 10° separation, two 57Co and two 60Co point sources with 20° separation, as well as a 2 × 3 137Cs point-source array with 20° separation. (4) Conclusions: We conclude that the proposed gamma camera design has comprehensive merits, including portability, 4π-view FOV, and good angular resolution across a wide energy range. The presented approach has promising potential in nuclear security applications.

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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.º 01 (1 de janeiro de 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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Zhang, Jipeng, Xiong Xiao, Ye Chen, Bin Zhang, Xinhua Ma, Xianyun Ai e Jinglun Li. "A Portable Three-Layer Compton Camera for Wide-Energy-Range Gamma-ray Imaging: Design, Simulation and Preliminary Testing". Sensors 23, n.º 21 (3 de novembro de 2023): 8951. http://dx.doi.org/10.3390/s23218951.

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(1) Background: The imaging energy range of a typical Compton camera is limited due to the fact that scattered gamma photons are seldom fully absorbed when the incident energies are above 3 MeV. Further improving the upper energy limit of gamma-ray imaging has important application significance in the active interrogation of special nuclear materials and chemical warfare agents, as well as range verification of proton therapy. (2) Methods: To realize gamma-ray imaging in a wide energy range of 0.3~7 MeV, a principle prototype, named a portable three-layer Compton camera, is developed using the scintillation detector that consists of an silicon photomultiplier array coupled with a Gd3Al2Ga3O12:Ce pixelated scintillator array. Implemented in a list-mode maximum likelihood expectation maximization algorithm, a far-field energy-domain imaging method based on the two interaction events is applied to estimate the initial energy and spatial distribution of gamma-ray sources. The simulation model of the detectors is established based on the Monte Carlo simulation toolkit Geant4. The reconstructed images of a 133Ba, a 137Cs and a 60Co point-like sources have been successfully obtained with our prototype in laboratory tests and compared with simulation studies. (3) Results: The proportion of effective imaging events accounts for about 2%, which allows our prototype to realize the reconstruction of the distribution of a 0.05 μSv/h 137Cs source in 10 s. The angular resolution for resolving two 137Cs point-like sources is 15°. Additional simulated imaging of the 6.13 MeV gamma-rays from 14.1 MeV neutron scattering with water preliminarily demonstrates the imaging capability for high incident energy. (4) Conclusions: We conclude that the prototype has a good imaging performance in a wide energy range (0.3~7 MeV), which shows potential in several MeV gamma-ray imaging applications.

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Li, Hui, e Wenbiao Chen. "Unintended findings: Therapeutic effects of hormones or gamma globulins on Lentiform Fork sign in 3 diabetic uremic patients: Case report/case series". Medicine 102, n.º 34 (25 de agosto de 2023): e34819. http://dx.doi.org/10.1097/md.0000000000034819.

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Introduction: The lentiform fork sign (LFS) is a unique magnetic resonance imaging (MRI) finding characterized by a bright hyperintense rim delineating the lentiform nucleus as a fork associated with metabolic acidosis in end-stage renal disease. Patient concerns: We report 3 cases of LFS in diabetic uremic patients. In one case of uremia, intensive hemodialysis treatment was not effective. Given our poor understanding of LFS, it was regarded as bilateral basal ganglia pathology, and pulse hormone and gamma globulins therapy was initiated. The patient neurological symptoms improved, and the pathological signs on imaging subsided. Based on our experience with the first LFS case, 2 diabetic uremic cases presenting with LFS were successfully treated with hormone or gamma globulin pulse therapy in addition to intensive hemodialysis. Diagnosis: Based on the clinical manifestations, past medical history and MRI imaging changes of the 3 cases reported here, the diagnosis of LFS was established. Interventions: Our experience from these 3 cases suggests that hormone supplementation and gamma globulin therapy may be indicated for treating LFS. Lessons: Our findings highlight that in diabetic uremic dialysis patients with neurological symptoms, LFS should be suspected. The clinical manifestations, past medical history and MRI imaging findings are essential for diagnosing LFS. Hormone supplementation and gamma globulin therapy may be the effective treatment for LFS.

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Wonho Lee e D. K. Wehe. "3-D isotropic imaging of environmental sources using a compact gamma camera". IEEE Transactions on Nuclear Science 51, n.º 5 (outubro de 2004): 2267–72. http://dx.doi.org/10.1109/tns.2004.834714.

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Cervantes, Hernán J., Christianne C. Cavinato, Letícia L. Campos e Said R. Rabbani. "Gamma Knife® 3-D Dose Distribution Mapping by Magnetic Resonance Imaging". Applied Magnetic Resonance 39, n.º 4 (2 de outubro de 2010): 357–64. http://dx.doi.org/10.1007/s00723-010-0166-4.

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Bower, Geoffrey C. "Millimeter VLBI Observations of the Gamma-Ray Blazar NRAO 530". International Astronomical Union Colloquium 164 (1998): 41–42. http://dx.doi.org/10.1017/s0252921100044432.

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AbstractWe present here 3 epochs of 3 and 7 millimeter wavelength VLBI observations and 2 epochs of lower frequency VLBA imaging of the gamma-ray blazar NRAO 530. These observations document the evolution of the parsec scale jet in this source during the brightest flare in 3 decades. New jet components were created during the flare and are probably related to an increase in gamma-ray activity. The components travel at superluminal velocities, further confirming the connection between superluminal sources and gamma-ray blazars. The rapid evolution of the source makes tracking of components difficult. It appears that either components significantly decelerate or that there is rapid cooling and acceleration of elections. We may be identifying structure due to standing shocks. The jet is bent on all scales between 100 μarcsec to 10 arcsec. The results indicate the ability of 3 mm wavelength imaging to probe the nuclei of blazars rapidly and reliably.

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Watanabe, Yoichi, Chung K. Lee e Bruce J. Gerbi. "Geometrical accuracy of a 3-tesla magnetic resonance imaging unit in Gamma Knife surgery". Journal of Neurosurgery 105, Supplement (dezembro de 2006): 190–93. http://dx.doi.org/10.3171/sup.2006.105.7.190.

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ObjectThe authors sought to evaluate and improve the geometrical accuracy of a 3-tesla magnetic resonance (MR) imaging unit used for Gamma Knife surgery (GKS).MethodsTo evaluate the geometrical accuracy of a Siemens Magnetom Trio 3-tesla MR imaging unit, two phantoms were used. Both phantoms were imaged with computed tomography (CT), a 1.5-tesla MR imaging unit (Siemens Avanto), and the 3-tesla MR imaging unit. A pair of orthogonal films was obtained with a radiotherapy simulator to validate the spatial coordinates of the marker positions determined with CT. The coordinates of the markers were measured using the GammaPlan treatment planning software. Magnetic resonance imaing was performed using three-dimensional (3D) magnetization-prepared rapid acquisition gradient echo (MPRAGE) and fast low-angle shot sequence (FLASH) pulse sequences. The voxel size was 1 × 1 × 1 mm3.Conclusions The root-mean-square error of MR images was 2 ± 0.73 mm for 3D MPRAGE. The error was reduced to 1.5 ± 0.64 mm for FLASH. The errors were decreased further by applying an image distortion correction method (the field-of-view filter) to the images acquired with FLASH. The mean errors were 1.3 ± 0.39 mm and 1.5 ± 0.77 mm for the two phantoms. The errors increased from 1 mm to 3.1 mm as the measurement points approached the caudal edge of the head coil (larger z value). Proper selection of a pulse sequence together with a geometrical distortion correction improved the geometrical accuracy of MR images. However, further study is needed to increase the geometrical accuracy of 3-tesla MR imaging units for radiosurgical applications.

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Vetter, Kai, Ross Barnowski, Joshua W. Cates, Andrew Haefner, Tenzing H. Y. Joshi, Ryan Pavlovsky e Brian J. Quiter. "Advances in Nuclear Radiation Sensing: Enabling 3-D Gamma-Ray Vision". Sensors 19, n.º 11 (4 de junho de 2019): 2541. http://dx.doi.org/10.3390/s19112541.

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The enormous advances in sensing and data processing technologies in combination with recent developments in nuclear radiation detection and imaging enable unprecedented and “smarter” ways to detect, map, and visualize nuclear radiation. The recently developed concept of three-dimensional (3-D) Scene-data fusion allows us now to “see” nuclear radiation in three dimensions, in real time, and specific to radionuclides. It is based on a multi-sensor instrument that is able to map a local scene and to fuse the scene data with nuclear radiation data in 3-D while the instrument is freely moving through the scene. This new concept is agnostic of the deployment platform and the specific radiation detection or imaging modality. We have demonstrated this 3-D Scene-data fusion concept in a range of configurations in locations, such as the Fukushima Prefecture in Japan or Chernobyl in Ukraine on unmanned and manned aerial and ground-based platforms. It provides new means in the detection, mapping, and visualization of radiological and nuclear materials relevant for the safe and secure operation of nuclear and radiological facilities or in the response to accidental or intentional releases of radioactive materials where a timely, accurate, and effective assessment is critical. In addition, the ability to visualize nuclear radiation in 3-D and in real time provides new means in the communication with public and facilitates to overcome one of the major public concerns of not being able to “see” nuclear radiation.

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Bhandari, Harish B., Vladimir Gelfandbein, Stuart R. Miller, Akash Agarwal, Brian W. Miller, H. Bradford Barber e Vivek V. Nagarkar. "Large-Area Crystalline Microcolumnar LaBr$_{3}$:Ce for High-Resolution Gamma Ray Imaging". IEEE Transactions on Nuclear Science 60, n.º 1 (fevereiro de 2013): 3–8. http://dx.doi.org/10.1109/tns.2012.2213612.

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KUIKKA, J. T., M. TENHUNEN-ESKELINEN, J. JURVELIN e H. KIILI??NEN. "Physical performance of the Siemens MultiSPECT 3 gamma camera". Nuclear Medicine Communications 14, n.º 6 (junho de 1993): 490–97. http://dx.doi.org/10.1097/00006231-199306000-00013.

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Cappello, Salvatore, Calogero Pace, Aldo Parlato, Salvatore Rizzo e Elio Tomarchio. "Gamma-ray irradiation tests of CMOS sensors used in imaging techniques". Nuclear Technology and Radiation Protection 29, suppl. (2014): 14–19. http://dx.doi.org/10.2298/ntrp140ss14c.

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Technologically-enhanced electronic image sensors are used in various fields as diagnostic techniques in medicine or space applications. In the latter case the devices can be exposed to intense radiation fluxes over time which may impair the functioning of the same equipment. In this paper we report the results of gamma-ray irradiation tests on CMOS image sensors simulating the space radiation over a long time period. Gamma-ray irradiation tests were carried out by means of IGS-3 gamma irradiation facility of Palermo University, based on 60Co sources with different activities. To reduce the dose rate and realize a narrow gamma-ray beam, a lead-collimation system was purposely built. It permits to have dose rate values less than 10 mGy/s and to irradiate CMOS Image Sensors during operation. The total ionizing dose to CMOS image sensors was monitored in-situ, during irradiation, up to 1000 Gy and images were acquired every 25 Gy. At the end of the tests, the sensors continued to operate despite a background noise and some pixels were completely saturated. These effects, however, involve isolated pixels and therefore, should not affect the image quality.

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Liscak, Roman. "Gamma Knife Radiosurgery for Vestibular Schwannomas". An International Journal of Otorhinolaryngology Clinics 3, n.º 1 (2011): 57–64. http://dx.doi.org/10.5005/jp-journals-10003-1054.

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ABSTRACT The current gamma knife radiosurgery technique involves the use of magnetic resonance imaging for targeting, the application of a low marginal dose (usually between 12 and 13 Gy) and highly conformal treatment planning using multiple small isocenters. This technique achieves an average tumor control rate of 95% and open surgery is needed in fewer than 2 to 3% of patients treated by gamma knife. Facial nerve function preservation is achieved in up to 99% of cases and chance of preserving serviceable hearing is usually between a 70 to 80%. The introduction of ventriculoperitoneal drainage after radiosurgery is required for 1 to 8% of patients. Gamma knife radiosurgery can be treatment of choice for the patients, where the diameter of the tumor is less than 3 cm.

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Liu, Xiao, Hui Liu, Li Cheng, Jing Wu, Tianwei Bao, Rutao Yao e Yaqiang Liu. "A 3-dimensional stationary cascade gamma-ray coincidence imager". Physics in Medicine & Biology 66, n.º 22 (5 de novembro de 2021): 225001. http://dx.doi.org/10.1088/1361-6560/ac311b.

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Mukai, Atsushi, Minato Kanda, Kenji Shimazoe, Fumihiko Ishida, Eiji Takada, Yusuke Tamura, Hanwool Woo et al. "Development of Unmanned Remote System to Find Radiation Sources Based on 4π Gamma Imaging". Journal of Robotics and Mechatronics 36, n.º 1 (20 de fevereiro de 2024): 79–87. http://dx.doi.org/10.20965/jrm.2024.p0079.

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A prototype system based on a combination of 4π sensitive gamma imaging and simultaneous localization and mapping (SLAM) was developed to find unknown radiation source(s) rapidly. The system consisted of a spherical visible camera, a three-dimensional light detection and ranging, a CdTe pixel array detector for 4π gamma imaging, a portable battery, and a control laptop personal computer; these were mounted on an unmanned vehicle. In a search area of 16 × 16 m2 with a height of 3 m, the prototype system successfully demonstrated the finding of a 137Cs point source with an activity of 0.67 MBq in the surrounding thin walls.

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Cussonneau, J. P., J. M. Abaline, S. Acounis, N. Beaupère, J. L. Beney, J. Bert, S. Bouvier et al. "3$\gamma $ Medical Imaging with a Liquid Xenon Compton Camera and $^{44}$Sc Radionuclide". Acta Physica Polonica B 48, n.º 10 (2017): 1661. http://dx.doi.org/10.5506/aphyspolb.48.1661.

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Brown, Steven T., David Goodman, Jiyang Chu, Bennett Williams, Martin R. Williamson e Zhong He. "Time-Encoded Gamma-Ray Imaging Using a 3-D Position-Sensitive CdZnTe Detector Array". IEEE Transactions on Nuclear Science 67, n.º 2 (fevereiro de 2020): 464–72. http://dx.doi.org/10.1109/tns.2019.2953182.

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Jaafar, Abdullah, Mohd Khairi Mohd Said, Nur Aira Abdul Rahman, Salzali Mohd, Mohamad Rabaie Shari, Nolida Yussop, Syirrazie Che Soh et al. "Development of a Gamma-Ray Process Tomography System for Hydrodynamic Characterisation of Multiphase Reactors". Applied Mechanics and Materials 83 (julho de 2011): 41–47. http://dx.doi.org/10.4028/www.scientific.net/amm.83.41.

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Gamma-ray computed tomography (CT) is a powerful non-invasive imaging technique for viewing an object in 2-D or 3-D cross-section images without the need to physically section it. The invention of CT technique revolutionised the field of medical diagnostic imaging because it provides more detailed and useful information than any previous non-invasive imaging technique. The method is increasingly used in industrial fields. This paper describes the development of a gamma-ray computed tomography system for imaging and visualising of industrial multiphase reactors. The theoretical aspects of CT scanner, the system configurations and the adopted algorithm for image reconstruction are discussed. Penetrating radiation from an isotopic gamma-ray source of Cs-137 and a bank of NaI(Tl) scintillation detectors in combination with a dedicated mechanical gantry set-up were used to construct the CT system. During scanning, the movement of the detector’s bank and rotation table is controlled by a LabView-based software. The software is also designed to control all associated nuclear electronics equipments and finally to acquire gamma-ray transmission data. The image reconstruction is performed by using Expectation-Maximisation (EM) and Alternating-Maximisation (AM) algorithms written in Visual-Fortran programming language. Several physical phantoms to simulate industrial multiphase process columns and reactors were scanned using this CT scanner. Some of the reconstructed images are presented in this paper.

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Das, Biswajit, R. Palit, R. Donthi, A. Kundu, S. R. Laskar, P. Dey, D. Negi et al. "Development of a position-sensitive fast scintillator (LaBr₃(Ce)) detector setup for gamma-ray imaging application". EPJ Web of Conferences 253 (2021): 11005. http://dx.doi.org/10.1051/epjconf/202125311005.

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We have characterized a Cerium doped Lanthanum Bromide (LaBr3(Ce) ) crystal coupled with the position-sensitive photo-multiplier system for the gamma-ray imaging application. One can use this detector set-up for the scanning of high purity germanium detectors for pulse shape analysis in gamma-ray spectroscopy experiments and the image formation of an object by Compton back-scattering . The sensor has been tested for energy, timing and position information of the gamma-rays interacting within the detector crystal. The GEANT4 simulation results are consistent with the experimental results. We have reconstructed the image of irradiation spots in different positions throughout the detector crystal. Position resolution is found to be around 3.5 mm with the 2 mm collimated gamma-rays. The 2-d image of hexagonal Bismuth Germanate (BGO) crystal and a cylindrical LaBr3(Ce) crystal have been reconstructed in coincidence technique. The performance of the detector for imaging application has been investigated by coincidence technique in GEANT4 simulation and compared with the experimental data. We have reconstructed the 2-d images of objects with various geometrical shapes by Compton back-scattered events of the gamma-rays. This position-sensitive detector can be used as an absorber of a Compton camera for the image reconstruction of an extended radioactive source. One can also use this kind of set-up as in radiation imaging and many other applications where the energy and source position of the gamma-ray is the main interest.

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Shi, Wei-Qun, Jun-Chen Dong, Yu-Fen Zhao e Yan-Mei Li. "Hydroxylation of 3-Nitrotyrosine and Its Derivatives by Gamma Irradiation". Radiation Research 166, n.º 4 (outubro de 2006): 639–45. http://dx.doi.org/10.1667/rr0612.1.

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Qi, Mingying, Guozhong Wu, Shimou Chen e Yaodong Liu. "Gamma Radiolysis of Ionic Liquid 1-Butyl-3-methylimidazolium Hexafluorophosphate". Radiation Research 167, n.º 5 (maio de 2007): 508–14. http://dx.doi.org/10.1667/rr0727.1.

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Zhang, Jun, Ziting Fan, Xile Zhang, Ruijie Yang e Junhai Wen. "Development of an Electronic Portal Imaging Device Dosimetry Method". Diagnostics 11, n.º 9 (9 de setembro de 2021): 1654. http://dx.doi.org/10.3390/diagnostics11091654.

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Support arm backscatter and off-axis effects of an electronic portal imaging device (EPID) are challenging for radiotherapy quality assurance. Aiming at the issue, we proposed a simple yet effective method with correction matrices to rectify backscatter and off-axis responses for EPID images. First, we measured the square fields with ionization chamber array (ICA) and EPID simultaneously. Second, we calculated the dose-to-pixel value ratio and used it as the correction matrix of the corresponding field. Third, the correction value of the large field was replaced with that of the same point in the small field to generate a correction matrix suitable for different EPID images. Finally, we rectified the EPID image with the correction matrix, and then the processed EPID images were converted into the absolute dose. The calculated dose was compared with the measured dose via ICA. The gamma pass rates of 3%/3 mm and 2%/2 mm (5% threshold) were 99.6% ± 0.94% and 95.48% ± 1.03%, and the average gamma values were 0.28 ± 0.04 and 0.42 ± 0.05, respectively. Experimental results verified our method accurately corrected EPID images and converted pixel values into absolute dose values such that EPID was an efficient radiotherapy dosimetry tool.

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Madhok, Ricky, Douglas Kondziolka, John C. Flickinger e L. Dade Lunsford. "GAMMA KNIFE RADIOSURGERY FOR FACIAL SCHWANNOMAS". Neurosurgery 64, n.º 6 (1 de junho de 2009): 1102–5. http://dx.doi.org/10.1227/01.neu.0000343743.20297.fb.

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Abstract OBJECTIVE Patients who have a schwannoma of the facial nerve (facial schwannoma, facial neuroma) can be managed with observation, surgical resection, stereotactic radiosurgery, or fractionated radiotherapy. Attempted complete resection is associated with facial weakness. The role of radiosurgery in these patients remains to be defined. METHODS We reviewed the clinical and imaging outcomes in patients who underwent gamma knife radiosurgery for a facial schwannoma. RESULTS Six patients had radiosurgery and were followed for a mean and median of 46.6 and 61.5 months, respectively (21–85 months). Three had a previous resection, and in 3 the diagnosis was made based on clinical and imaging criteria. All patients had facial nerve symptoms (5 had weakness and 1 had muscle twitching). House-Brackmann grades before radiosurgery were as follows: 1 (n = 1), 2 (n = 3), 3 (n = 1), and 6 (n = 1). The radiosurgery margin dose was 12 or 12.5 Gy. On later imaging, 3 tumors had regressed (with the longest follow-up duration) and 3 were unchanged. All patients had preservation of their preradiosurgery facial function. No other adverse effects were noted and all patients maintained their preradiosurgery level of hearing. CONCLUSION Over a mean of almost 4 years of follow-up, radiosurgery was shown to be a safe and effective management for residual and newly diagnosed facial schwannomas.

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Baek, Seung-Hyeop, Sang-Hyoun Choi, Moo-Jae Han, Gyu-Seok Cho, Wonil Jang, Jin-Sung Kim e Kum-Bae Kim. "Clinical Efficacy of an Electronic Portal Imaging Device versus a Physical Phantom Tool for Patient-Specific Quality Assurance". Life 12, n.º 11 (18 de novembro de 2022): 1923. http://dx.doi.org/10.3390/life12111923.

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Pre-treatment patient-specific quality assurance (QA) is critical to prevent radiation accidents. The electronic portal imaging device (EPID) is a dose measurement tool with good resolution and a low volume-averaging effect. EPIbeam—an EPID-based portal dosimetry software—has been newly installed in three institutions in Korea. This study evaluated the efficacy of the EPID-based patient-specific QA tool versus the PTW729 detector (a previously used QA tool) based on gamma criteria and planning target volume (PTV). A significant difference was confirmed through the R statistical analysis software. The average gamma passing rates of PTW729 and EPIbeam were 98.73% and 99.60% on 3 mm/3% (local), 96.66% and 97.91% on 2 mm/2% (local), and 88.41% and 74.87% on 1 mm/1% (local), respectively. The p-values between them were 0.015 (3 mm/3%, local), 0.084 (2 mm/2%, local), and less than 0.01 (1 mm/1%, local). Further, the average gamma passing rates of PTW 729 and EPIbeam according to PTV size were 99.55% and 99.91% (PTV < 150 cm3) and 97.91% and 99.28% (PTV > 150 cm3), respectively. The p-values between them were 0.087 (PTV < 150 cm3) and 0.036 (PTV > 150 cm3). These results confirm that EPIbeam can be an effective patient-specific QA tool.

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Scopinaro, Francesco, Roberto Pani, Alessandro Soluri, Rosanna Pellegrini, Raffaele Scafò, Giuseppe De Vincentis, Francesca Capoccetti, Vincenzo David, Stella Chiarini e Salvatore Stella. "Detection of Sentinel Node in Breast Cancer: Pilot Study with the Imaging Probe". Tumori Journal 86, n.º 4 (julho de 2000): 329–31. http://dx.doi.org/10.1177/030089160008600420.

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The commonly used gamma probes are easy to use but also give rough information when employed in radioisotope-guided surgery. When images are required for exact localization, a gamma camera as well as a probe have to be used. Position-sensitive photomultipliers have contemporaneously allowed high-resolution scintigraphy and miniaturization of gamma cameras. We have assembled a miniature gamma camera with a 1-square-inch field of view and an intrinsic resolution of about 1 mm. When the minicamera is collimated with a large-holed, highly sensitive collimator, it acquires a spatial resolution of 3 mm. This prototype has been tested in the detection of difficult-to-image breast cancer sentinel nodes. Five nodes that had not been found with the usual technique of an Anger camera plus conventional probe were checked with the miniature camera that we named imaging probe: it actually is small enough to be used as a probe and large enough to give an image. One of the five nodes was found and imaged. It was small, disease-free, close to the tumor and probably hidden by the Compton halo around the peritumoral injection site. Our pilot study shows that the imaging probe, although still a prototype, has certain advantages over conventional methods when lymph node localization is required during surgery.

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Zulkafal, Hafiz Muhibb ullah, Allah Ditta Khalid, Sajid Anees Minhas, Umair Zafar, Rizwan Hameed, Muhammad Afzal Khan e Khalid Iqbal. "RapidArc treatment planning quality assurance using electronic portal imaging device for cervical cancer". Journal of Radiotherapy in Practice 19, n.º 2 (30 de julho de 2019): 139–44. http://dx.doi.org/10.1017/s1460396919000542.

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AbstractPurpose:The main objective of this study is to assure the quality of cervical cancer treatment plans using an electronic portal imaging device (EPID) in RapidArc techniques.Materials and Methods:Fifteen cases of cervical cancer patients undergoing RapidArc technique were selected to evaluate the quality assurance (QA) of their treatment. The computed tomography (CT) of each patient was obtained with 3-mm-slice thickness and transferred to the Eclipse treatment planning system. The prescribed dose (PD) of 50·4 Gy with 1·8 Gy per fraction to planning target volume (PTV) was used for each patient. The aim of treatment planning was to achieve 95% of PD to cover 97%, and dose to the PTV should not receive 105% of the PD. All RapidArc plans were created using the AAA algorithm and treated on Varian DHX using 6 MV photon beam, with two full arcs. Gamma analysis was used to evaluate the quality of the treatment plans with accepting criteria of 95% at 3%/3 mm.Results:In this study, maximum and average gamma values were 2·53 ± 0·409 and 0·195 ± 0·059 showing very small deviation and indicating the smaller difference between both predicted and portal doses. Gamma Area changes from > 0·8 to > 1·2. SD increased to 5·4% and mean standard error increased to 4·67%.Conclusion:On the basis of these outcomes, we can summarise that the EPID is a useful tool for QA in standardising and evaluating RapidArc treatment plans of cervical cancer in routine clinical practice.

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Shehaby, Amr El, Jeremy C. Ganz, Wael A. Reda e Ayman Hafez. "Temporary symptomatic swelling of meningiomas following gamma knife surgery". Journal of Neurosurgery 102, Special_Supplement (janeiro de 2005): 293–96. http://dx.doi.org/10.3171/sup.2005.102.s_supplement.0293.

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✓ In two patients in whom gamma knife surgery was performed for meningiomas clinically significant volume increases were observed in the first 3 months after treatment. Clinical examination and various imaging studies form the basis of the report in these patients. In each case, the volume increase was temporary.

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Madsen, Jan L., Katarina Sjögreen-Gleisner, Dennis R. Elema, Lasse R. Søndergaard, Palle Rasmussen, Stefan Fuglsang, Michael Ljungberg e Morten Damgaard. "Gamma camera imaging for studying intestinal absorption and whole-body distribution of selenomethionine". British Journal of Nutrition 111, n.º 3 (9 de agosto de 2013): 547–53. http://dx.doi.org/10.1017/s0007114513002559.

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Se metabolism in humans is not well characterised. Currently, the estimates of Se absorption, whole-body retention and excretion are being obtained from balance and tracer studies. In the present study, we used gamma camera imaging to evaluate the whole-body retention and distribution of radiolabelled selenomethionine (SeMet), the predominant form of Se present in foods. A total of eight healthy young men participated in the study. After consumption of a meal containing 4 MBq [75Se]l-SeMet ([75Se]SeMet), whole-body gamma camera scanning was performed for 45 min every hour over a 6 h period, every second hour for the next 18 h and once on each of the subsequent 6 d. Blood, urine and faecal samples were collected to determine the plasma content of [75Se]SeMet as well as its excretion in urine and faeces. Imaging showed that 87·9 (sd 3·3) % of the administered activity of [75Se]SeMet was retained within the body after 7 d. In contrast, the measured excretion in urine and faeces for the 7 d period was 8·2 (sd 1·1) % of the activity. Time–activity curves were generated for the whole body, stomach, liver, abdomen (other than the stomach and the liver), brain and femoral muscles. Gamma camera imaging allows for the assessment of the postprandial absorption of SeMet. This technique may also permit concurrent studies of organ turnover of SeMet.

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Labagnoy, Yasmine Joy M., Sornjarod Oonsiri, Mananchaya Vimolnoch e Sakda Kingkaew. "Assessment of the Dosimetric Performance of the Mobius3D against Portal Dose Measurements in Patient-specific Quality Assurance". Journal of Medical Physics 48, n.º 4 (2023): 350–57. http://dx.doi.org/10.4103/jmp.jmp_19_23.

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Aim: The Mobius3D software addresses limitations lacking in measurement-based methods in patient-specific quality assurance (QA). The objective of this study was to validate its dosimetric performance against conventionally used portal dose measurements using gamma analysis and confidence limits. Materials and Methods: A total of 240 patient-specific QA plans for the Varian Halcyon linear accelerator were collected. The Mobius3D software was commissioned through beam data and plan verification. All plans underwent QA through the electronic portal imaging device, coupled with the Portal Dosimetry software, and the Mobius3D. Data were assessed using >95% gamma pass. Portal measurements were evaluated using 3%/2 mm and 3%/3 mm criteria, whereas Mobius3D was analyzed at 3%/3 mm and 5%/3 mm, at the 10% threshold. Results: Mobius 5%/3 mm mean gamma passes were 99.89% for volumetric-modulated arc therapy (VMAT) and 99.31% for intensity-modulated radiotherapy (IMRT), and correspondingly, the data for portal 3%/2 mm were 99.99% and 99.96%. The Mobius3D at 5%/3 mm can perform like Portal 3%/2 mm for VMAT plans at 0.1% difference, especially for head/neck and pelvic/abdominal cases. In IMRT-based treatments, at 0.7% difference in Mobius3D 5%/3 mm and Portal 3%/2 mm, the performance and error identification in IMRT plans should be applied more carefully due to the amount of failed plans, particularly the chest region. The confidence limits for VMAT plans for Portal 3%/2 mm and Mobius 5%/3 mm are 99.93% and 99.42%, respectively, while for IMRT plans are 99.69% and 97.43%, respectively. Conclusions: At a 5%/3 mm criterion, the Mobius3D may yield percentage gamma pass rates like measurements obtained by Portal Dosimetry 3%/3 mm and Portal Dosimetry 3%/2 mm. As the software is largely dependent on commissioned data, rigorous commissioning and a comprehensive QA program should be implemented.

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Maraghechi, Borna, Jack Davis, Shyam Badu, Andre Fleck, Johnson Darko e Ernest Osei. "Retrospective analysis of portal dosimetry pre-treatment quality assurance of prostate volumetric-modulated arc therapy (VMAT) plans". Journal of Radiotherapy in Practice 17, n.º 1 (22 de agosto de 2017): 44–52. http://dx.doi.org/10.1017/s1460396917000486.

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AbstractBackgroundElectronic portal imaging device (EPID) offers high-resolution digital image that can be compared with a predicted portal dose image. A very common method to quantitatively compare a measured and calculated dose distribution that is routinely used for quality assurance (QA) of volumetric-modulated arc therapy (VMAT) and intensity-modulated radiation therapy treatment plans is the evaluation of the gamma index. The purpose of this work was to evaluate the gamma passing rate (%GP), maximum gamma (γmax), average gamma (γave), maximum dose difference (DDmax) and the average dose difference (DDave) for various regions of interest using Varian’s implementation of three absolute dose gamma calculation techniques of improved, local, and combined improved and local.Methods and materialsWe analyzed 232 portal dose images from 100 prostate cancer patients’ VMAT plans obtained using the Varian EPID on TrueBeam Linacs.ResultsOur data show that the %GP, γmax and γave depend on the gamma calculation method and the acceptance criteria. Higher %GP values were obtained compared with both our current institutional action level and the American Association of Physicists in Medicine Task Group 119 recommendations.ConclusionsThe results of this study can be used to establish stricter action levels for pre-treatment QA of prostate VMAT plans. A stricter 3%/3 mm improved gamma criterion with a passing rate of 97% or the 2%/2 mm improved gamma criterion with a passing rate of 95% can be achieved without additional measurements or configurations.

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Payne, Bryan Rankin, Dheerendra Prasad, György Szeifert, Melita Steiner e Ladislau Steiner. "Gamma surgery for intracranial metastases from renal cell carcinoma". Journal of Neurosurgery 92, n.º 5 (maio de 2000): 760–65. http://dx.doi.org/10.3171/jns.2000.92.5.0760.

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Object. The goal of this study was to evaluate the effectiveness and limitations of gamma surgery (GS) in the treatment of renal cell carcinoma that has metastasized to the brain.Methods. The authors performed a retrospective analysis of a consecutive series of 21 patients with 37 metastatic brain deposits from renal cell carcinoma who were treated with GS at the University of Virginia from 1990 to 1999.Clinical data were available in all patients. No patient died of progression of intracranial disease or deteriorated neurologically following GS. Eight patients clinically improved. Follow-up imaging studies were available for 23 tumors in 12 patients. Nine patients did not undergo follow-up imaging. One patient lived 17 months and succumbed to systemic disease; no brain imaging was performed in this case. Another patient refused further imaging and lived 7 months. Seven patients lived up to 4 months after the procedure; however, their physicians did not require these patients to undergo follow-up imaging examinations because of their general conditions—all had systemic progression of disease. Of the 23 tumors that were observed posttreatment, one remained unchanged in volume, 16 decreased in volume, and six disappeared. No tumor progressed at any time, and there were no radiation-induced changes on follow-up imaging an average of 21 months after GS (range 3–63 months).Conclusions. Gamma surgery provides an alternative to surgical resection of metastatic brain deposits from renal cell carcinoma. Neurological side effects were seen in only one case; freedom from progression of disease was achieved in all cases.

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NIIDA, H., Y. NAKAYAMA e K. YAGI. "244. Investigation of Brain 3-D Surface Imaging using PRISM-3000 Three-Head Gamma Camera System". Japanese Journal of Radiological Technology 49, n.º 8 (1993): 1269. http://dx.doi.org/10.6009/jjrt.kj00003324832.

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Abbene, Leonardo, Fabio Principato, Antonino Buttacavoli, Gaetano Gerardi, Manuele Bettelli, Andrea Zappettini, Saverio Altieri et al. "Potentialities of High-Resolution 3-D CZT Drift Strip Detectors for Prompt Gamma-Ray Measurements in BNCT". Sensors 22, n.º 4 (15 de fevereiro de 2022): 1502. http://dx.doi.org/10.3390/s22041502.

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Recently, new high-resolution cadmium–zinc–telluride (CZT) drift strip detectors for room temperature gamma-ray spectroscopic imaging were developed by our group. The CZT detectors equipped with orthogonal anode/cathode collecting strips, drift strips and dedicated pulse processing allow a detection area of 6 × 20 mm2 and excellent room temperature spectroscopic performance (0.82% FWHM at 661.7 keV). In this work, we investigated the potentialities of these detectors for prompt gamma-ray spectroscopy (PGS) in boron neutron capture therapy (BNCT). The detectors, exploiting the measurement of the 478 keV prompt gamma rays emitted by 94% 7Li nuclides from the 10B(n, α)7Li reaction, are very appealing for the development of single-photon emission computed tomography (SPECT) systems and Compton cameras in BNCT. High-resolution gamma-ray spectra from 10B samples under thermal neutrons were measured at the T.R.I.G.A. Mark II research nuclear reactor of the University of Pavia (Italy).

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Egarievwe, Stephen U., Utpal N. Roy, Carmella A. Goree, Benicia A. Harrison, Jeanette Jones e Ralph B. James. "Ammonium Fluoride Passivation of CdZnTeSe Sensors for Applications in Nuclear Detection and Medical Imaging". Sensors 19, n.º 15 (25 de julho de 2019): 3271. http://dx.doi.org/10.3390/s19153271.

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Cadmium zinc telluride selenide (Cd1−xZnxTe1−ySey or CZTS) is one of the emerging CdTe-based semiconductor materials for detecting X- and gamma-ray radiation at or near room temperature (i.e., without cryogenic cooling). Potential applications of CZTS sensors include medical imaging, X-ray detection, and gamma-ray spectroscopy. Chemical passivation of CZTS is needed to reduce the conductivity of Te-rich surfaces, which reduces the noise and improves the device performance. In this study, we focus on the effect of surface passivation of CZTS using a 10% aqueous solution of ammonium fluoride. The effects of the chemical treatment were studied on the leakage current, charge transport measured as the electron mobility-lifetime (µτ) product, and the spectral resolution measured as the full-width at half-maximum (FWHM) of specific peaks. After passivation, the leakage current increased and began to decrease towards pre-passivation levels. The energy resolutions were recorded for eight applied voltages between −35 V and −200 V. The results showed an average of 25% improvement in the detector’s energy resolution for the 59.6 keV gamma peak of Am-241. The electron µτ product was unchanged at 2 × 10−3 cm2/V. These results show that ammonium fluoride is effective for chemical passivation of CZTS detectors.

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Guo, Fanqing. "3-D treatment planning system—Leksell Gamma Knife treatment planning system". Medical Dosimetry 43, n.º 2 (2018): 177–83. http://dx.doi.org/10.1016/j.meddos.2018.03.001.

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Monkhoev, R., M. Ternovoy, I. Astapov, P. Bezyazeekov, A. Borodin, M. Brueckner, N. Budnev et al. "Geant4 simulation of the Tunka-Grande experiment". Journal of Physics: Conference Series 2103, n.º 1 (1 de novembro de 2021): 012001. http://dx.doi.org/10.1088/1742-6596/2103/1/012001.

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Abstract The Tunka-Grande array is part of a single experimental complex, which also includes the Tunka-133 and TAIGA-HiScORE (High Sensitivity COsmic Rays and gamma Explorer) wide-angle Cherenkov arrays, TAIGA-IACT array (Imaging Atmospheric Cherenkov Telescope) and TAGA-MUON scintillation array. This complex is located in the Tunka Valley (Buryatia Republic, Russia), 50 km from Lake Baikal. It is designed to study the energy spectrum and the mass composition of charged cosmic rays in the energy range 100 TeV - 1000 PeV, to search for diffuse gamma rays above 100 TeV and to study local sources of gamma rays with energies above 30 TeV. This report outlines 3 key points. The first is the description of the Tunka-Grande scintillation array. The second one presents the computer simulation strategy of the Tunka Grande array based on the Geant4 software. The third one is devoted to the prospects for future research in the field of cosmic ray physics and gamma-ray astronomy using simulation results.

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Song, Y., M. Zhang, B. J. Duan, W. P. Yan, L. Sheng, G. Z. Song, J. M. Ma, C. C. Han e Z. M. Yao. "A high-speed radiation imaging system based on liquid scintillator filled capillary arrays". Review of Scientific Instruments 93, n.º 3 (1 de março de 2022): 033702. http://dx.doi.org/10.1063/5.0066686.

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A high-speed radiation imaging system based on an image converter of liquid scintillator filled capillary arrays has been developed, which is sensitive to x rays, gamma rays, and neutrons. This imaging system has advantages of both high spatial resolution and high sensitivity because increasing the thickness of the image converter only leads to little deterioration on imaging resolution. The capillary arrays have dimensions of 150 mm diameter and 50 mm thickness, with 100 µm diameter of each capillary. The fluorescence decay time of the filled liquid scintillator based on the mixture of p-xylene and 2,5-diphenyloxazole has been evaluated to be ∼3 ns with the single photon method under the gamma ray excitation. The spatial resolution has been experimentally evaluated to be about 1.15 and 0.6 mm, under excitation of x rays and neutrons, respectively. The imaging system has been applied for diagnosing the dynamic x-ray spot generated by the rod pinch. Two frames in single shot with 15 ns temporal resolution and 20 ns inter-frame separation time have been obtained, which show the spatiotemporal distribution of the electrons bombarding the tungsten rod, indicating the ability of this imaging system in diagnosing dynamic radiation objects. In addition, the technique of capillary arrays provides a promising path for applications of advanced liquid scintillators in the field of radiation imaging.

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Maraghechi, Borna, Jack Davis, Nicholas Mitchell, Meeral Shah, Andre Fleck, Johnson Darko e Ernest Osei. "The sensitivity of gamma index analysis to detect multileaf collimator (MLC) positioning errors using Varian TrueBeam EPID and ArcCHECK for patient-specific prostate volumetric-modulated arc therapy (VMAT) quality assurance". Journal of Radiotherapy in Practice 17, n.º 1 (11 de julho de 2017): 66–77. http://dx.doi.org/10.1017/s1460396917000425.

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AbstractBackgroundDue to the increased degree of modulation and complexity of volumetric-modulated arc therapy (VMAT) plans, it is necessary to have a pre-treatment patient-specific quality assurance (QA) programme. The gamma index is commonly used to quantitatively compare two dose distributions. In this study we investigated the sensitivity of single- and multi-gamma criteria techniques to detect multileaf collimator (MLC) positioning errors using the Varian TrueBeam Electronic Portal Imaging DeviceTM (EPID) dosimetry and the ArcCHECKTM device.Materials and methodsAll active MLC positions of seven intact prostate patients VMAT plans were randomly changed with a mean value of 0.25, 0.5, 1 and 2 mm and a standard deviation of 0.1 mm on 25, 50, 75 and 100% of the control points. The change in gamma passing rates of six gamma criteria of 3%/3 mm, 3%/2 mm, 3%/1 mm, 2%/2 mm, 2%/1 mm and 1%/1 mm were analysed individually (single-gamma criterion) and as a group (multi-gamma criteria) as a function of the simulated errors. We used the improved and global gamma calculation algorithms with a low dose threshold of 10% in the EPID and ArcCHECK software, respectively. The changes in the planning target volume dose distributions and the organs at risk due to the MLC positioning errors were also studied.ResultsWhen 25, 50, 75 and 100% of the control points were modified by the introduction of the simulated errors, the smallest detectable errors with the EPID were 2, 1, 0.5 and 0.5 mm, respectively, using the multi-gamma criteria technique. Similarly for the single-gamma criteria technique errors as small as 2, 1, 1 and 1 mm applied to 25, 50, 75 and 100% of the control points, respectively, were detectable using a 2%/2 mm criterion. However, the smallest detectable errors with the ArcCHECK when using the multi-gamma criteria technique were 2, 2 and 1 mm when MLC errors were applied on 50, 75 and 100% of the control points. When only 25% of the control points were affected the ArcCHECK were unable to detect any of the errors applied. No noticeable difference was observed in the sensitivity using the single- or the multi-gamma criteria techniques with the ArcCHECK.ConclusionThe Varian TrueBeam EPID dosimetry shows a higher sensitivity in detecting MLC positioning errors compared with the ArcCHECK regardless of using the single- or the multi-gamma criteria techniques. Higher sensitivity was observed using the multi-gamma criteria technique compared with the single-criterion technique when using the EPID.

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Kooshkabadi, Ali, L. Dade Lunsford, Daniel Tonetti, John C. Flickinger e Douglas Kondziolka. "Gamma Knife thalamotomy for tremor in the magnetic resonance imaging era". Journal of Neurosurgery 118, n.º 4 (abril de 2013): 713–18. http://dx.doi.org/10.3171/2013.1.jns121111.

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Object The surgical management of disabling tremor has gained renewed vigor with the availability of deep brain stimulation. However, in the face of an aging population of patients with increasing surgical comorbidities, noninvasive approaches for tremor management are needed. The authors' purpose was to study the technique and results of stereotactic radiosurgery performed in the era of MRI targeting. Methods The authors evaluated outcomes in 86 patients (mean age 71 years; number of procedures 88) who underwent a unilateral Gamma Knife thalamotomy (GKT) for tremor during a 15-year period that spanned the era of MRI-based target selection (1996–2011). Symptoms were related to essential tremor in 48 patients (19 age ≥ 80 years and 3 age ≥ 90 years), Parkinson disease in 27 patients (11 age ≥ 80 years [1 patient underwent bilateral procedures]), and multiple sclerosis in 11 patients (1 patient underwent bilateral procedures). A single 4-mm isocenter was used to deliver a maximum dose of 140 Gy to the posterior-inferior region of the nucleus ventralis intermedius. The Fahn-Tolosa-Marin clinical tremor rating scale was used to grade tremor, handwriting, and ability to drink. The median follow-up was 23 months. Results The mean tremor score was 3.28 ± 0.79 before and 1.81 ± 1.15 after (p < 0.0001) GKT; the mean handwriting score was 2.78 ± 0.82 and 1.62 ± 1.04, respectively (p < 0.0001); and the mean drinking score was 3.14 ± 0.78 and 1.80 ± 1.15, respectively (p < 0.0001). After GKT, 57 patients (66%) showed improvement in all 3 scores, 11 patients (13%) in 2 scores, and 2 patients (2%) in just 1 score. In 16 patients (19%) there was a failure to improve in any score. Two patients developed a temporary contralateral hemiparesis, 1 patient noted dysphagia, and 1 sustained facial sensory loss. Conclusions Gamma Knife thalamotomy in the MRI era was a safe and effective noninvasive surgical strategy for medically refractory tremor in the elderly or those with contraindications to deep brain stimulation or stereotactic radiofrequency (thermal) thalamotomy.

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Kim, Myoung Hyoun, Seul-Gi Kim e Dae-Weung Kim. "A novel dual-labeled small peptide as a multimodal imaging agent for targeting wild-type EGFR in tumors". PLOS ONE 17, n.º 2 (4 de fevereiro de 2022): e0263474. http://dx.doi.org/10.1371/journal.pone.0263474.

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The epidermal growth factor receptor (EGFR) is over-expressed in various human cancer. The over-expression of EGFR in tumors is an excellent target for the development of cancer imaging agents. In the present study, we developed Tc-99m SYPIPDT-GHEG-ECG-K-tetramethylrhodamine (SYPIPDT-ECG-TAMRA) as a molecular imaging agent targeting wild-type EFGR (wtEGFR)-positive tumor cells, and verified its feasibility as molecular imaging agent. SYPIPDT-ECG-TAMRA was synthesized using Fmoc solid-phase peptide synthesis. The radiolabeling of SYPIPDT-ECG-TAMRA with Tc-99m was accomplished using ligand exchange via tartrate. Cellular uptake and binding affinity studies were performed. In vivo gamma camera imaging, ex vivo imaging and biodistribution studies were performed using NCI-H460 and SW620 tumor-bearing murine models. After radiolabeling procedures with Tc-99m, Tc-99m SYPIPDT-ECG-TAMRA complexes were prepared at high yield (> 95%). The binding affinity value (Kd) of Tc-99m SYPIPDT-ECG-TAMRA for NCI-H460 cells was estimated to be 76.5 ± 15.8 nM. In gamma camera imaging, the tumor to normal muscle uptake ratios of Tc-99m SYPIPDT-ECG-TAMRA increased with time (2.7 ± 0.6, 4.0 ± 0.9, and 6.2 ± 1.0 at 1, 2, and 3 h, respectively). The percentage injected dose per gram of wet tissue for the NCI-H460 tumor was 1.91 ± 0.11 and 1.70 ± 0.22 at 1 and 3 h, respectively. We developed Tc-99m SYPIPDT-ECG-TAMRA, which is dual-labeled with both radioisotope and fluorescence. In vivo and in vitro studies demonstrated specific uptake of Tc-99m SYPIPDT-ECG-TAMRA into wtEGFR-positive NCI-H460 cells and tumors. Thus, the results of the present study suggest that Tc-99m SYPIPDT-ECG-TAMRA is a potential dual-modality imaging agent targeting wtEGFR.

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Zwierzchowski, Grzegorz, Grzegorz Bieleda e Janusz Skowronek. "Quality assurance procedures based on dosimetric, gamma analysis as a fast reliable tool for commissioning brachytherapy treatment planning systems". Radiology and Oncology 51, n.º 4 (29 de novembro de 2017): 469–74. http://dx.doi.org/10.1515/raon-2017-0050.

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Abstract Background Fast and easily repeatable methods for commissioning procedures for brachytherapy (BT) treatment planning systems (TPS) are needed. Radiochromic film dosimetry with gamma analysis is widely used in external beam quality assurance (QA) procedures and planar film dosimetry is also increasingly used for verification of the dose distribution in BT applications. Using the gamma analysis method for comparing calculated and measured dose data could be used for commissioning procedures of the newly developed TG-186 and MBDCA calculation algorithms. The aim of this study was dosimetric verification of the calculation algorithm used in TPS when the CT/MRI ring applicator is used. Materials and methods Ring applicators with 26 and 30 mm diameters and a 60 mm intra-uterine tube with 60° angle were used for verification. Gafchromic® EBT films were used as dosimetric media. Dose grids, corresponding to each plane (dosimetric film location), were exported from the TPS as a raw data. Gafchromic® films were digitized after irradiation. gamma analysis of the data were performed using the OMNI Pro I’mRT® system, as recommended by the AAPM TG-119 rapport criterion for gamma analysis of 3%, 3 mm and a level of 95%. Results For the 26 mm and 30 mm rings, the average gamma ranged, respectively, from 0.1 to 0.44 and from 0.1 to 0.27. In both cases, 99% of the measured points corresponded with the calculated data. Conclusions This analysis showed excellent agreement between the dose distribution calculated with the TPS and the doses measured by Gafchromic films. This finding confirms the viability of using film dosimetry in BT.

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Fullbrook, A., L. Wright, H. Massouh, J. R. W. Hall e R. J. Morton. "Comparison of 1′′ and 3/8′′ NaI crystal for routine gamma camera work". Nuclear Medicine Communications 25, n.º 4 (abril de 2004): 424–25. http://dx.doi.org/10.1097/00006231-200404000-00114.

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Omori, Yasutaka, Atsuyuki Sorimachi, Manlaijav Gun-Aajav, Nyamdavaa Enkhgerel, Galnemekh Oyunbolor, Enkhtuya Palam e Chieri Yamada. "ELEVATION OF GAMMA DOSE RATE BY CONSTRUCTION OF THE ASIAN HIGHWAY 3 (AH3) BETWEEN ULAANBAATAR AND SAINSHAND, MONGOLIA". Radiation Protection Dosimetry 184, n.º 1 (12 de outubro de 2018): 127–34. http://dx.doi.org/10.1093/rpd/ncy173.

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Abstract The present study aimed at examining changes of gamma radiation level associated with road construction in Mongolia. A car-borne survey of gamma dose rate was made for a paved, ~450-km long part of the Asian Highway 3 between Ulaanbaatar and Sainshand. The gamma dose rates ranged from 48 to 173 nGy/h. Elevation of the gamma dose rates was observed only on a 86-km long segment of the survey route which was newly constructed from 2011 to 2013. The gamma dose rates over the newer paved segment were twice as high as those over the bare dirt surface alongside it. Outdoor measurements of gamma-ray pulse height distributions also indicated an abundance of natural radionuclides, especially 232Th-series elements in road materials. These findings suggest that the gamma dose rates were elevated by introduction of road materials containing large amounts of natural radionuclides.

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Jensen, Morten B., Peter Balling, Hans L. Riis, Anders S. Bertelsen, Simon V. Jensen, Simon J. Doran, Jørgen B. B. Petersen e Ludvig P. Muren. "Characterisation and application of three-dimensional silicone-based radiochromic dosimetry in 1.5 T magnetic resonance imaging-guided radiotherapy". Journal of Physics: Conference Series 2630, n.º 1 (1 de novembro de 2023): 012030. http://dx.doi.org/10.1088/1742-6596/2630/1/012030.

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Abstract The magnetic field in magnetic resonance imaging-guided radiotherapy (MRgRT) systems influences the three-dimensional (3D) dose deposition and hence the delivered dose distributions. The aim of this study was to investigate the dose-rate dependency and dose response of silicone-based radiochromic dosimeters for photon irradiation in the precense of a magnetic field using a 1.5 T MRgRT system. Additionally, the study aimed to provide a proof of the concept of radiotherapy treatment based on a treatment plan calculated on magnetic resonance imaging rather than a computed tomography (CT) scan. The delivered dose was read out in 3D with an optical CT scanner and the dose distribution was verified using gamma analysis. We found an insignificant dose-rate dependency for dose rates ranging from 3.2 to 5.1 Gy/min and a linear dose response up to 20 Gy. A 3D 3%/3mm gamma analysis showed a pass rate of 95.1%. The dosimeter showed clinical potential for 3D dose verification of MRgRT delivery.

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Patt, Bradley E., Jan S. Iwanczyk, Martin P. Tornai, Craig S. Levin e Edward J. Hoffman. "Development of a Mercuric Iodide Detector Array For In-Vivo X-Ray Imaging". Advances in X-ray Analysis 38 (1994): 615–24. http://dx.doi.org/10.1154/s0376030800018310.

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Abstract A nineteen element mercuric iodide (HgI2) detector array has been developed in order to investigate the potential of using this technology for in-vivo x-ray and gamma-ray imaging. A prototype cross-grid detector array was constructed with hexagonal pixels of 1.9 mm diameter (active area = 3.28 mm2) and 0.2 mm thick septa. The overall detector active area is roughly 65 mm2. A detector thickness of 1.2 mm was used to achieve about 100% efficiency at 60 keV and 67% efficiency at 140 keV The detector fabrication, geometry and structure were optimized for charge collection and to minimize crosstalk between elements. A section of a standard high resolution cast-lead gamma-camera collimator was incorporated into the detector to provide collimation matching the discrete pixel geometry. Measurements of spectral and spatial performance of the array were made using 241-Am and 99m-Tc sources. These measurements were compared with similar measurements made using an optimized single HgI2 x-ray detector with active area of about 3 mm2 and thickness of 500 μm.

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Draeger, E., H. Chen, D. Mackin, S. Peterson, S. Avery, S. Beddar e J. Polf. "TU-FG-BRB-05: A 3 Dimensional Prompt Gamma Imaging System for Range Verification in Proton Radiotherapy". Medical Physics 43, n.º 6Part35 (junho de 2016): 3757. http://dx.doi.org/10.1118/1.4957545.

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Pittori, Carlotta. "AGILE Highlights after Six Years in Orbit". Acta Polytechnica CTU Proceedings 1, n.º 1 (4 de dezembro de 2014): 157–62. http://dx.doi.org/10.14311/app.2014.01.0157.

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AGILE is an ASI space mission in collaboration with INAF, INFN and CIFS, dedicated to the observation of the gamma-ray Universe in the 30 MeV - 50 GeV energy range, with simultaneous X-ray imaging capability in the 18-60 keV band. The AGILE satellite was launched on April 23rd, 2007, and produced several important scientic results, among which the unexpected discovery of strong <br />ares from the Crab Nebula. This discovery won to the AGILE PI and the AGILE Team the Bruno Rossi Prize for 2012 by the High Energy Astrophysics division of the American Astronomical Society. Thanks to its sky monitoring capability and fast ground segment alert system, AGILE detected many Galactic and extragalactic sources: among other results AGILE discovered gamma-ray emission from the microquasar Cygnus X-3, detected many bright blazars, discovered several new gamma-ray pulsars, and discovered emission up to 100 MeV from Terrestrial Gamma-Ray Flashes. We present an overview of the main AGILE Data Center activities and the AGILE scientic highlights after 6 years of operations.

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Valkema, R., H. Prpic, J. A. K. Blokland, J. A. J. Camps, S. E. Papapoulos, O. L. M. Bijvoet e E. K. J. Pauwels. "Dual Photon Absorptiometry for Bone Mineral Measurements Using a Gamma Camera". Acta Radiologica 35, n.º 1 (janeiro de 1994): 45–52. http://dx.doi.org/10.1177/028418519403500110.

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A gamma camera was equipped with a special collimator and arm assembly for bone mineral measurements with dual photon absorptiometry (DPA). The system was evaluated in vitro and in vivo and compared both with a rectilinear DPA and a dual energy X-ray (DEXA) system. All 3 systems showed a linear response in measurements of 4 vials, containing different amounts of hydroxyapatite. Phantom measurements with the gamma camera system showed a precision of 1.6% to 2.8%. Results obtained in 8 healthy volunteers with rectilinear and gamma camera systems were well correlated (R2 = 0.78). With the photon beam directed from posterior to anterior, the separation of vertebrae was easy with the gamma camera system. We conclude that bone mineral measurements can be made with a gamma camera for assessment of fracture risk and in the decision process whether a patient needs treatment or not. For follow-up, the precision of DPA with a gamma camera is inadequate.

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