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- Lisi, Matteo, 1982-, et al.
(författare)
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Severity of aortic stenosis predicts early post-operative normalization of left atrial size and function detected by myocardial strain
- 2013
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Ingår i: International Journal of Cardiology. - : Elsevier BV. - 0167-5273 .- 1874-1754. ; 167:4, s. 1450-1455
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Aortic stenosis (AS) causes significant disturbances in left ventricular (LV) and left atrial (LA) function irrespective of the extent of myocardial hypertrophy which associates the increased afterload. We hypothesize that aortic valve replacement (AVR) and removal of LV outflow tract obstruction should result in LA size and function recovery, even partial, and were set to study this in a group of patients with AVR for AS.METHODS: Peak atrial longitudinal strain (PALS) was evaluated in 43 patients with severe isolated AS and normal EF (56.6±3.8%) and no obstructive coronary artery disease candidates for AVR, pre-operatively and then 40days and 3months after surgery. Results were compared with those from 34 age- and gender-matched healthy controls.RESULTS: LVEF remained unchanged and LV mass regressed after AVR. Global PALS was reduced pre-operatively and increased 40days after surgery (p=0.002) and showed only a slight further increase at 3months follow-up (p<0.0001). Indexed LA volume was increased before surgery, but significantly fell 40days after surgery (p<0.0001) and showed only a slight further reduction after 3months (p<0.0001). Trans-aortic mean gradient change after surgery was the only independent predictor of the recovery of LA size and function.CONCLUSIONS: AVR reverses LA abnormalities and regains normal atrial function, a behavior which is directly related to the severity of pre-operative LV outflow tract obstruction. Early identification of LA size enlargement and functional disturbances might contribute to better patient's recruitment for AVR.
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- 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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- 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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- 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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- 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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