| 1. |
- Bennati, Paolo, et al.
(författare)
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Preliminary study of a new gamma imager for on-line proton range monitoring during proton radiotherapy
- 2017
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Ingår i: Journal of Instrumentation. - : Institute of Physics Publishing (IOPP). - 1748-0221. ; 12:5
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Tidskriftsartikel (refereegranskat)abstract
- We designed and tested new concept imaging devices, based on a thin scintillating crystal, aimed at the online monitoring of the range of protons in tissue during proton radiotherapy. The proposed crystal can guarantee better spatial resolution and lower sensitivity with respect to a thicker one, at the cost of a coarser energy resolution. Two different samples of thin crystals were coupled to a position sensitive photo multiplier tube read out by 64 independent channels electronics. The detector was equipped with a knife-edge Lead collimator that defined a reasonable field of view of about 10 cm in the target. Geant4 Monte Carlo simulations were used to optimize the design of the experimental setup and assess the accuracy of the results. Experimental measurements were carried out at the Skandion Clinic, the recently opened proton beam facility in Uppsala, Sweden. PMMA and water phantoms studies were performed with a first prototype based on a round 6.0 mm thick Cry019 crystal and with a second detector based on a thinner 5 × 5 cm2, 2.0 mm thick LFS crystal. Phantoms were irradiated with mono-energetic proton beams whose energy was in the range between 110 and 160 MeV. According with the simulations and the experimental data, the detector based on LFS crystal seems able to identify the peak of prompt-gamma radiation and its results are in fair agreement with the expected shift of the proton range as a function of energy. The count rate remains one of the most critical limitations of our system, which was able to cope with only about 20% of the clinical dose rate. Nevertheless, we are confident that our study might provide the basis for developing a new full-functional system.
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| 2. |
- Borrarzo, Cristian, et al.
(författare)
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Monte Carlo Simulation to Evaluate Factors Affecting Imaging Performances of Compact Scintillation Gamma Camara
- 2016
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Ingår i: 2016 IEEE NUCLEAR SCIENCE SYMPOSIUM, MEDICAL IMAGING CONFERENCE AND ROOM-TEMPERATURE SEMICONDUCTOR DETECTOR WORKSHOP (NSS/MIC/RTSD). - : IEEE. - 9781509016426
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Konferensbidrag (refereegranskat)abstract
- In recent years, a new generation of compact gamma cameras, based on monolithic scintillation crystals, has become increasingly widespread. The main advantages of small FoV gamma cameras with respect to the standard ones are high portability, low cost and low weight, allowing several clinical applications, from scintimammography to intraoperative tumor localization. In gamma cameras based on continuous scintillation crystals, intrinsic Spatial Resolution (SR) is mainly affected by two factors: scintillation light collection efficiency and overall crystal thickness. The first affects the counting statistics, the latter impacts on the light distribution width. To fully investigate the potentiality of these devices we took advantage of Monte Carlo simulations as a valuable tool to physically characterize the imaging systems and to establish a priori reference values. GEANT4 toolkit allows to completely describe the phenomenon of light emission and propagation through the media, providing control to all second-order factors existing in real systems. Results show clearly that SR is dependent on the number of photoelectrons produced and on the light spread. Furthermore, the role of refractive index has been unambiguously identified as an important factor affecting light collection and consequently SR.
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| 3. |
- Borrazzo, Cristian, et al.
(författare)
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PET and MRI-guided focused ultrasound surgery for Neurological Applications
- 2016
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Ingår i: 2016 IEEE NUCLEAR SCIENCE SYMPOSIUM, MEDICAL IMAGING CONFERENCE AND ROOM-TEMPERATURE SEMICONDUCTOR DETECTOR WORKSHOP (NSS/MIC/RTSD). - : IEEE. - 9781509016426
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Konferensbidrag (refereegranskat)abstract
- Magnetic Resonance (MR) guided Focused Ultrasound Surgery (MRgFUS) technology, combined with High Intensity Focused Ultrasound (HIFU) beams, has opened to new therapeutic protocols for various pathological conditions. The success of this therapy relies on the accuracy of the guidance for therapy provided by thermal mapping of sonication, which is obtained with MR imaging. In addition, in recent years, multimodality Positron Emission Tomography and Magnetic Resonance Imaging (PET/MRI) imaging has been developed. This technique is able to provide simultaneous functional and soft tissue morphological imaging and, for this reason, it is particularly engaging for brain imaging. The key concept behind this work is to assess the feasibility of a brain-dedicated PET-and MRI-guided FUS device providing real-time evaluation of the outcome of the HIFU therapy. At first, a method to improve imaging capabilities of small-ring PET scanners will be presented. It will be showed that thanks to this method it is possible to obtain high tomographic spatial resolution with an affordable, brain-dedicated, PET scanner based on monolithic scintillation crystals and able to work as an insert in a MRI system. Moreover, simulations of an anthropomorphic phantom will be made in order to evaluate the effect of different HIFU protocols and, in addition, to investigate the capability of thermal maps provided by MRI for assessing the effect of the HIFU treatment. Finally, from the comparison of the spatial resolutions provided by each imaging technique (PET, MRI and thermal MRI) and the HIFU therapy, it will be possible to assess the feasibility of the proposed multimodality device. The system suggested in this work should be composed of a MRI scanner with a PET insert and a customized MRI-compatible focused ultrasound applicator. It could be very useful for the diagnosis and therapy of brain tumors thanks to the possibility of a real-time evaluation of the effect of the HIFU treatment. The protocol for the therapy could be executed in three main steps: the diagnosis of the pathological condition by means of fused anatomical imaging from MRI and functional imaging from PET (with different radiotracers) that allow to identify the region where apply the therapy, the ablation of the tumor by means of HIFU beams and the simultaneous evaluation of the thermal response of the tissues by means MRI thermal maps and, finally, the assessment of the outcome of the therapy by means, again, of PET/MRI hybrid imaging. The results suggest that PET and MRI-guided focused ultrasound surgery (PET/MRgFUS) could be an innovative, feasible and engaging technique for tumor ablation in the brain.
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| 4. |
- Cameli, Matteo, et al.
(författare)
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Comparison of Right Versus Left Ventricular Strain Analysis as a Predictor of Outcome in Patients With Systolic Heart Failure Referred for Heart Transplantation
- 2013
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Ingår i: American Journal of Cardiology. - : Elsevier. - 0002-9149 .- 1879-1913. ; 112:11, s. 1778-1784
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Tidskriftsartikel (refereegranskat)abstract
- The aim of the present study was to explore the relation between right ventricular (RV) and left ventricular (LV) echocardiographic parameters with clinical outcome in patients with advanced heart failure referred for cardiac transplantation. Ninety-eight consecutive patients with advanced systolic heart failure, referred for cardiac transplant evaluation, were enrolled. All patients were prospectively followed for the development of new outcome events, which included hospitalization for acute heart failure, cardiovascular death, heart transplantation, intra-aortic balloon pump implantation, and ventricular assist device implantation. Conventional transthoracic echocardiography was performed in all subjects. RV longitudinal strain (RVLS) by speckle-tracking echocardiography was assessed by averaging all segments in apical 4-chamber view (global RVLS) and by averaging RV free-wall segments (free-wall RVLS). LV global longitudinal and global circumferential strains were also calculated. Of the 98 subjects at baseline, 46 had 67 new events during a mean follow-up of 1.5 +/- 0.9 years. Free-wall RVLS, global RVLS, N-terminal fragment of the prohormone brain natriuretic peptide, RV fractional area change, and LV end-diastolic volume were independently predictive of combined outcomes (all p<0.0001). The overall performance for the prediction of cardiovascular events was greatest for free-wall RVLS (area under the curve free-wall RVLS: 0.87; global RVLS: 0.67; RV fractional area change: 0.60; N-terminal fragment of the prohormone brain natriuretic peptide, 0.62; global circumferential strain: 0.55; global longitudinal strain: 0.35; and LV ejection fraction: 0.26). Free-wall RVLS showed the highest adjusted hazards ratio. A graded association between the grade of RV dysfunction and the risk of cardiovascular events was only evident for free-wall RVLS and global RVLS. In conclusion, in patients referred for heart transplantation, RVLS is a stronger predictor of outcome than LV longitudinal strain and other conventional parameters, providing a stronger prognostic stratification.
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| 5. |
- Cinti, M. N., et al.
(författare)
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Innovative LuYAP:Ce array for PET imaging
- 2017
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Ingår i: Journal of Instrumentation. - : Institute of Physics Publishing (IOPP). - 1748-0221. ; 12:3
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Tidskriftsartikel (refereegranskat)abstract
- We present an imaging characterization of a 10 x 10 LuYAP array (2 x 2 x 10 mm3 pixels) with an innovative dielectric coating insulation (0.015 mm thick), in view of its possible use in a gamma camera for imaging positron emission tomography (PET) or in similar applications, e.g. as γ-prompt detector in hadron therapy. The particular assembly of this array was realized in order to obtain a packing fraction of 98%, improving detection efficiency and light collection. For imaging purpose, the array has been coupled with a selected Hamamatsu H10966-100 Multi Anode Photomultiplier read out by a customized 64 independent channels electronics. This tube presents a superbialkali photocathode with 38% of quantum efficiency, permitting to enhance energy resolution and consequently image quality. A pixel identification of about 0.5 mm at 662 keV was obtained, highlighting the potentiality of this detector in PET applications.
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| 6. |
- Pani, R., et al.
(författare)
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A study of response of a LuYAP : Ce array with innovative assembling for PET
- 2015
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 795, s. 82-87
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Tidskriftsartikel (refereegranskat)abstract
- We propose the characterization of a first array of 10×10 Lutetium Yttrium Orthoaluminate Perovskite (LuYAP:Ce) crystals, 2 mm×2 mm×10 mm pixel size, with an innovative assembling designed to enhance light output, uniformity and detection efficiency. The innovation consists of the use of 0.015 mm thick dielectric coating as inter-pixel light-insulators, manufactured by Crytur (Czech Republic) intended to improve crystal insulation and then light collection. Respect to the traditional treatment with 0.2 mm of white epoxy, a thinner pixel gap enhances packing fraction up to 98% with a consequent improvement of detection efficiency. Spectroscopic characterization of the array was performed by a Hamamatsu R6231 photomultiplier tube. A pixel-by-pixel scanning with a collimated 99mTc radioisotope (140 keV photon energy) highlighted a deviation in pulse height close to 3.5% respect to the overall mean value. Meanwhile, in term of energy resolution a difference between the response of single pixel and the array of about 10% was measured. Results were also supported and validated by Monte Carlo simulations performed with GEANT4. Although the dielectric coating pixel insulator cannot overcome the inherent limitations of LuYAP crystal due to its self-absorption of light (still present), this study demonstrated that the new coating treatment allows better light collection (nearly close to the expected one) with in addition a very good uniformity between different pixels. These results confirm the high potentiality of this coating for any other crystal array suited for imaging application and new expectations for the use of LuYAP for PET systems.
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| 7. |
- Polito, C., et al.
(författare)
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Dual-modality imaging with a ultrasound-gamma device for oncology
- 2018
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Ingår i: Radiation Physics and Chemistry. - : Elsevier. - 0969-806X .- 1879-0895. ; 147, s. 77-84
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Tidskriftsartikel (refereegranskat)abstract
- Recently, dual-modality systems have been developed, aimed to correlate anatomical and functional information, improving disease localization and helping ontological or surgical treatments.& para;& para;Moreover, due to the growing interest in handheld detectors for preclinical trials or small animal imaging, in this work a new dual modality integrated device, based on a Ultrasounds probe and a small Field of View Single Photon Emission gamma camera, is proposed.
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