Management of severe epistaxis during pregnancy: a case report and review of the literature

Epistaxis is a common problem during pregnancy. Few cases of severe epistaxis, not associated with nasal lesions or clotting disorders, were described in the literature. We reported a case of severe epistaxis in a pregnant patient, exploring all the different possible management options

Analysis of time-profiles with in-beam PET monitoring in charged particle therapy

Background: Treatment verification with PET imaging in charged particle therapy is conventionally done by comparing measurements of spatial distributions with Monte Carlo (MC) predictions. However, decay curves can provide additional independent information about the treatment and the irradiated tissue. Most studies performed so far focus on long time intervals. Here we investigate the reliability of MC predictions of space and time (decay rate) profiles shortly after irradiation, and we show how the decay rates can give an indication about the elements of which the phantom is made up. Methods and Materials: Various phantoms were irradiated in clinical and near-clinical conditions at the Cyclotron Centre of the Bronowice proton therapy centre. PET data were acquired with a planar 16x16 cm$^2$ PET system. MC simulations of particle interactions and photon propagation in the phantoms were performed using the FLUKA code. The analysis included a comparison between experimental data and MC simulations of space and time profiles, as well as a fitting procedure to obtain the various isotope contributions in the phantoms. Results and conclusions: There was a good agreement between data and MC predictions in 1-dimensional space and decay rate distributions. The fractions of $^{11}$C, $^{15}$O and $^{10}$C that were obtained by fitting the decay rates with multiple simple exponentials generally agreed well with the MC expectations. We found a small excess of $^{10}$C in data compared to what was predicted in MC, which was clear especially in the PE phantom.Comment: 9 pages, 5 figures, 1 table. Proceedings of the 20th International Workshop on Radiation Imaging Detectors (iWorid2018), 24-28 June 2018, Sundsvall, Swede

Characterization and Test of a Data Acquisition System for PET

A small Positron Emission Tomography demonstrator based on LYSO slabs and Silicon Photomultiplier matrices is under construction at the University and INFN of Pisa. In this paper we present the characterization results of the read-out electronics and of the detection system. Two SiPM matrices, composed by 8 × 8 SiPM pixels, 1.5 mm pitch, have been coupled one to one to a LYSO crystals array. Custom Front-End ASICs were used to read the 64 channels of each matrix. Data from each Front-End were multiplexed and sent to a DAQ board for the digital conversion; a motherboard collects the data and communicates with a host computer through a USB port. Specific tests were carried out on the system in order to assess its performance. Futhermore we have measured some of the most important parameters of the system for PET application

Feasibility Study of a Small Animal PET Insert Based on a Single LYSO Monolithic Tube

[EN] There are drawbacks with using a Positron Emission Tomography (PET) scanner design employing the traditional arrangement of multiple detectors in an array format. Typically PET systems are constructed with many regular gaps between the detector modules in a ring or box configuration, with additional axial gaps between the rings. Although this has been significantly reduced with the use of the compact high granularity SiPM photodetector technology, such a scanner design leads to a decrease in the number of annihilation photons that are detected causing lower scanner sensitivity. Moreover, the ability to precisely determine the line of response (LOR) along which the positron annihilated is diminished closer to the detector edges because the spatial resolution there is degraded due to edge effects. This happens for both monolithic based designs, caused by the truncation of the scintillation light distribution, but also for detector blocks that use crystal arrays with a number of elements that are larger than the number of photosensors and, therefore, make use of the light sharing principle. In this report we present a design for a small-animal PET scanner based on a single monolithic annulus-like scintillator that can be used as a PET insert in high-field Magnetic Resonance systems. We provide real data showing the performance improvement when edge-less modules are used. We also describe the specific proposed design for a rodent scanner that employs facetted outside faces in a single LYSO tube. In a further step, in order to support and prove the proposed edgeless geometry, simulations of that scanner have been performed and lately reconstructed showing the advantages of the design.This project was funded in part by the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program (grant agreement No 695536). It has also been supported by the Spanish Ministerio de Economia, Industria y Competitividad under Grant TEC2016-79884-C2-1-R and through PROSPET (DTS15/00152) funded by the Ministerio de Economia y Competitividad. AR is a postdoctoral fellow of the FWO (project 12T7118N). The University of Virginia School of Medicine has provided seed funding for this project.González Martínez, AJ.; Berr, SS.; Cañizares-Ledo, G.; Gonzalez-Montoro, A.; Orero Palomares, A.; Correcher Salvador, C.; Rezaei, A.... (2018). Feasibility Study of a Small Animal PET Insert Based on a Single LYSO Monolithic Tube. Frontiers in Medicine. 5:1-8. https://doi.org/10.3389/fmed.2018.00328S185Kuntner, C., & Stout, D. (2014). Quantitative preclinical PET imaging: opportunities and challenges. Frontiers in Physics, 2. doi:10.3389/fphy.2014.00012Judenhofer, M. S., & Cherry, S. R. (2013). Applications for Preclinical PET/MRI. Seminars in Nuclear Medicine, 43(1), 19-29. doi:10.1053/j.semnuclmed.2012.08.004España, S., Marcinkowski, R., Keereman, V., Vandenberghe, S., & Van Holen, R. (2014). DigiPET: sub-millimeter spatial resolution small-animal PET imaging using thin monolithic scintillators. Physics in Medicine and Biology, 59(13), 3405-3420. doi:10.1088/0031-9155/59/13/3405Yang, Y., Bec, J., Zhou, J., Zhang, M., Judenhofer, M. S., Bai, X., … Cherry, S. R. (2016). A Prototype High-Resolution Small-Animal PET Scanner Dedicated to Mouse Brain Imaging. Journal of Nuclear Medicine, 57(7), 1130-1135. doi:10.2967/jnumed.115.165886Yamamoto, S., Watabe, H., Kanai, Y., Watabe, T., Kato, K., & Hatazawa, J. (2013). Development of an ultrahigh resolution Si-PM based PET system for small animals. Physics in Medicine and Biology, 58(21), 7875-7888. doi:10.1088/0031-9155/58/21/7875Yang, Y., James, S. S., Wu, Y., Du, H., Qi, J., Farrell, R., … Cherry, S. R. (2010). Tapered LSO arrays for small animal PET. Physics in Medicine and Biology, 56(1), 139-153. doi:10.1088/0031-9155/56/1/009Godinez, F., Gong, K., Zhou, J., Judenhofer, M. S., Chaudhari, A. J., & Badawi, R. D. (2018). Development of an Ultra High Resolution PET Scanner for Imaging Rodent Paws: PawPET. IEEE Transactions on Radiation and Plasma Medical Sciences, 2(1), 7-16. doi:10.1109/trpms.2017.2765486Gonzalez, A. J., Aguilar, A., Conde, P., Hernandez, L., Moliner, L., Vidal, L. F., … Benlloch, J. M. (2016). A PET Design Based on SiPM and Monolithic LYSO Crystals: Performance Evaluation. IEEE Transactions on Nuclear Science, 63(5), 2471-2477. doi:10.1109/tns.2016.2522179Moses, W. W. (2011). Fundamental limits of spatial resolution in PET. 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The MINDVIEW project: First results. European Psychiatry, 50, 21-27. doi:10.1016/j.eurpsy.2018.01.002Gonzalez-Montoro, A., Benlloch, J. M., Gonzalez, A. J., Aguilar, A., Canizares, G., Conde, P., … Sanchez, F. (2017). Performance Study of a Large Monolithic LYSO PET Detector With Accurate Photon DOI Using Retroreflector Layers. IEEE Transactions on Radiation and Plasma Medical Sciences, 1(3), 229-237. doi:10.1109/trpms.2017.2692819Moliner, L., González, A. J., Soriano, A., Sánchez, F., Correcher, C., Orero, A., … Benlloch, J. M. (2012). Design and evaluation of the MAMMI dedicated breast PET. Medical Physics, 39(9), 5393-5404. doi:10.1118/1.4742850Morrocchi, M., Ambrosi, G., Bisogni, M. G., Bosi, F., Boretto, M., Cerello, P., … Del Guerra, A. (2017). Depth of interaction determination in monolithic scintillator with double side SiPM readout. EJNMMI Physics, 4(1). doi:10.1186/s40658-017-0180-9Xie, S., Zhao, Z., Yang, M., Weng, F., Huang, Q., Xu, J., & Peng, Q. (2017). LOR-PET: a novel PET camera constructed with a monolithic scintillator ring. 2017 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC). doi:10.1109/nssmic.2017.8532627Stolin, A. V., Martone, P. F., Jaliparthi, G., & Raylman, R. R. (2017). Preclinical positron emission tomography scanner based on a monolithic annulus of scintillator: initial design study. Journal of Medical Imaging, 4(1), 011007. doi:10.1117/1.jmi.4.1.011007Gonzalez, A. J., Aguilar, A., Conde, P., Gonzalez-Montoro, A., Sanchez, S., Moliner, L., … Benlloch, J. M. (2016). Pilot tests of a PET insert based on monolithic crystals in a 7T MR. 2016 IEEE Nuclear Science Symposium, Medical Imaging Conference and Room-Temperature Semiconductor Detector Workshop (NSS/MIC/RTSD). doi:10.1109/nssmic.2016.8069496Jan, S., Santin, G., Strul, D., Staelens, S., Assié, K., Autret, D., … Bloomfield, P. M. (2004). GATE: a simulation toolkit for PET and SPECT. 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Timing performances of a data acquisition system for time of flight PET

We are investigating the performances of a data acquisition system for Time of Flight PET, based on LYSO crystal slabs and 64 channels Silicon Photomultipliers matrices (1.2 cm2 of active area each). Measurements have been performed to test the timing capability of the detection system (SiPM matices coupled to a LYSO slab and the read-out electronics) with both test signal and radioactive source

Proof of concept of an imaging system demonstrator for PET applications with SiPM

A PET imaging system demonstrator based on LYSO crystal arrays coupled to SiPM matrices is under construction at the University and INFN of Pisa. Two SiPM matrices, composed of 8×8 SiPM pixels, and 1,5 mm pitch, have been coupled one to one to a LYSO crystals array and read out by a custom electronics system. front-end ASICs were used to read 8 channels of each matrix. Data from each front-end were multiplexed and sent to a DAQ board for the digital conversion; a motherboard collects the data and communicates with a host computer through a USB port for the storage and off-line data processing. In this paper we show the first preliminary tomographic image of a point-like radioactive source acquired with part of the two detection heads in time coincidence

Analysis methods for in-beam PET images in proton therapy treatment verification: a comparison based on Monte Carlo simulations

Background and purpose: In-beam Positron Emission Tomography (PET) is one of the modalities that can be used for in-vivo non-invasive treatment monitoring in proton therapy. PET distributions obtained during various treatment sessions can be compared in order to identify regions that have anatomical changes. The purpose of this work is to test and compare different analysis methods in the context of inter-fractional PET image comparison for proton treatment verification. Methods: For our study we used the FLUKA Monte Carlo code and artificially generated CT scans to simulate in-beam PET distributions at different stages during proton therapy treatment. We compared the Beam-Eye-View method, the Most-Likely-Shift method, the Voxel-Based-Morphology method and the gamma evaluation method to compare PET images at the start of treatment, and after a few weeks of treatment. The results were compared to the CT scan. Results and conclusions: Three-dimensional methods like VBM and gamma are preferred above two-dimensional methods like MLS and BEV if much statistics is available, since the these methods allow to identify the regions with anomalous activity. The VBM approach has as disadvantage that a larger number of MC simulations is needed. The gamma analysis has the disadvantage that no clinical indication exist on tolerance criteria. In terms of calculation time, the BEV and MLS method are preferred. We recommend to use the four methods together, in order to best identify the location and cause of the activity changes.Comment: 9 pages, 5 figure