MVBatch: A matlab toolbox for batch process modeling and monitoring

[EN] A novel user-friendly graphical interface for process understanding, monitoring and troubleshooting has been developed as a freely available MATLAB toolbox, called the MultiVariate Batch (MVBatch) Toolbox. The main contribution of this software package is the integration of recent developments in Principal Component Analysis (PCA) based Batch Multivariate Statistical Process Monitoring (BMSPM) that overcome modeling problems such as missing data, different speed of process evolution and length of batch trajectories, and multiple stages. An interactive user interface is provided, which aims to guide users in handling batch data through the main BMSPM steps: data alignment, data modeling, and the development of monitoring schemes. In addition, a small-scale non-linear dynamic simulator of the fermentation process of the Saccharomyces cerevisiae cultivation is available to generate realistic batch data under normal and abnormal operating conditions. This generator of synthetic data can be used for teaching purposes or as a benchmark to illustrate and compare the performance of new methods with sound techniques published in the field of BMSPM.This work is partially supported by the Spanish Ministry of Economy and Competitiveness and FEDER funds through the projects DPI2017-82896-C2-1-R and TIN2017-83494-R. Authors also acknowledge the volunteers to test MVBatch and report their impressions for this software tutorial.González Martínez, JM.; Camacho Paez, J.; Ferrer, A. (2018). MVBatch: A matlab toolbox for batch process modeling and monitoring. Chemometrics and Intelligent Laboratory Systems. 183:122-133. https://doi.org/10.1016/j.chemolab.2018.11.001S12213318

Organ-Dedicated Molecular Imaging Systems

[EN] In this review, we will cover both clinical and technical aspects of the advantages and disadvantages of organ specific (dedicated) molecular imaging (MI) systems, namely positron emission tomography (PET) and single photon emission computed tomography, including gamma cameras. This review will start with the introduction to the organ-dedicated MI systems. Thereafter, we will describe the differences and their advantages/disadvantages when compared with the standard large size scanners. We will review time evolution of dedicated systems, from first attempts to current scanners, and the ones that ended in clinical use. We will review later the state of the art of these systems for different organs, namely: breast, brain, heart, and prostate. We will also present the advantages offered by these systems as a function of the special application or field, such as in surgery, therapy assistance and assessment, etc. Their technological evolution will be introduced for each organ-based imager. Some of the advantages of dedicated devices are: higher sensitivity by placing the detectors closer to the organ, improved spatial resolution, better image contrast recovery (by reducing the noise from other organs), and also lower cost. Designing a complete ring-shaped dedicated PET scanner is sometimes difficult and limited angle tomography systems are preferable as they have more flexibility in placing the detectors around the body/organ. Examples of these geometries will be presented for breast, prostate and heart imaging. Recently achievable excellent time of flight capabilities below 300-ps full width at half of the maximum reduce significantly the impact of missing angles on the reconstructed images.This work was supported in part by the European Research Council through the European Union's Horizon 2020 Research and Innovation Program under Grant 695536, in part by the EU through the FP7 Program under Grant 603002, and in part by the Spanish Ministerio de Economia, Industria y Competitividad through PROSPET (DTS15/00152) funded by the Ministerio de Economia y Competitividad under Grant TEC2016-79884-C2-1-R.González Martínez, AJ.; Sánchez, F.; Benlloch Baviera, JM. (2018). Organ-Dedicated Molecular Imaging Systems. IEEE Transactions on Radiation and Plasma Medical Sciences. 2(5):388-403. https://doi.org/10.1109/TRPMS.2018.2846745S3884032

In-depth evaluation of TOF-PET detectors based on crystal arrays and the TOFPET2 ASIC

[EN] In recent years high efforts have been devoted to enhance spatial and temporal resolutions of PET detectors. However, accurately combining these two main features is, in most of the cases, challenging. Typically, a compromise has to be made between the number of readout channels, scintillator type and size, and photosensors arrangement if aiming for a good system performance, while keeping a moderate cost. In this work, we have studied several detector configurations for PET based on a set of 8x8 Silicon Photomultiplier (SiPMs) of 3x3 mm(2) active area, and LYSO crystal arrays with different pixel sizes. An exhaustive evaluation in terms of spatial, energy and timing resolution was made for all detector configurations. In some cases, when using pixel sizes different than SiPM active area, a significant amount of scintillation light may spread among several SiPMs. Therefore, we made use of a calibration method considering the different SiPM timing contributions. Best Detector Time Resolution (DTR) of 156 ps FWHM was measured when using 3x3 mm(2) crystal pixels directly coupled to the 3x3 mm(2) SiPMs. However, when using 1.5 mm crystal pixels with the same photosensor array, although we could clearly resolve all crystal pixels, an average DTR of 250 ps FWHM was achieved. We also shed light in this work on the timing dependency of the crystal pixel and photosensor alignment.This project has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program (grant agreement No. 695536) and by the Spanish Ministerio de Economia, Industria y Competitividad under Grant TEC2016-79884-C2-1-R. The first author has also been supported by Generalitat Valenciana, Spain under grant agreement GRISOLIAP-2018-026.Lamprou, E.; Sánchez Martínez, F.; Benlloch Baviera, JM.; González Martínez, AJ. (2020). In-depth evaluation of TOF-PET detectors based on crystal arrays and the TOFPET2 ASIC. Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment. 977:1-8. https://doi.org/10.1016/j.nima.2020.164295S18977Jones, T., & Townsend, D. (2017). History and future technical innovation in positron emission tomography. Journal of Medical Imaging, 4(1), 011013. doi:10.1117/1.jmi.4.1.011013Surti, S. (2014). Update on Time-of-Flight PET Imaging. Journal of Nuclear Medicine, 56(1), 98-105. doi:10.2967/jnumed.114.145029Lecoq, P. (2017). Pushing the Limits in Time-of-Flight PET Imaging. IEEE Transactions on Radiation and Plasma Medical Sciences, 1(6), 473-485. doi:10.1109/trpms.2017.2756674Surti, S., & Karp, J. S. (2016). Advances in time-of-flight PET. Physica Medica, 32(1), 12-22. doi:10.1016/j.ejmp.2015.12.007Gundacker, S., Auffray, E., Pauwels, K., & Lecoq, P. (2016). Measurement of intrinsic rise times for various L(Y)SO and LuAG scintillators with a general study of prompt photons to achieve 10 ps in TOF-PET. Physics in Medicine and Biology, 61(7), 2802-2837. doi:10.1088/0031-9155/61/7/2802González-Montoro, A., Sánchez, F., Bruyndonckx, P., Cañizares, G., Benlloch, J. M., & González, A. J. (2019). Novel method to measure the intrinsic spatial resolution in PET detectors based on monolithic crystals. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 920, 58-67. doi:10.1016/j.nima.2018.12.056Moses, W. W. (2011). Fundamental limits of spatial resolution in PET. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 648, S236-S240. doi:10.1016/j.nima.2010.11.092Lamprou, E., Gonzalez, A. J., Sanchez, F., & Benlloch, J. M. (2020). Exploring TOF capabilities of PET detector blocks based on large monolithic crystals and analog SiPMs. Physica Medica, 70, 10-18. doi:10.1016/j.ejmp.2019.12.004Lamprou, E., Aguilar, A., González-Montoro, A., Monzó, J. M., Cañizares, G., Iranzo, S., … Benlloch, J. M. (2018). PET detector block with accurate 4D capabilities. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 912, 132-136. doi:10.1016/j.nima.2017.11.002A. Di Francesco, R. Bugalho, L. Oliveira, L. Pacher, A. Rivetti, M. Rolo, et al. TOFPET2: A high-performance ASIC for time and amplitude measurements of SiPM signals in time-of-flight applications, J. Instrum. 11 (03) C03042.Van Dam, H. T., Borghi, G., Seifert, S., & Schaart, D. R. (2013). Sub-200 ps CRT in monolithic scintillator PET detectors using digital SiPM arrays and maximum likelihood interaction time estimation. Physics in Medicine and Biology, 58(10), 3243-3257. doi:10.1088/0031-9155/58/10/3243V. Nadig, D. Schug, B. Weissler, V. Schulz, Evaluation Of The PETsys TOFPET2 ASIC In Multi-Channel Coincidence Experiments, arXiv:1911.08156.Gundacker, S., Turtos, R. M., Auffray, E., Paganoni, M., & Lecoq, P. (2019). High-frequency SiPM readout advances measured coincidence time resolution limits in TOF-PET. Physics in Medicine & Biology, 64(5), 055012. doi:10.1088/1361-6560/aafd52Gundacker, S., Acerbi, F., Auffray, E., Ferri, A., Gola, A., Nemallapudi, M. V., … Lecoq, P. (2016). State of the art timing in TOF-PET detectors with LuAG, GAGG and L(Y)SO scintillators of various sizes coupled to FBK-SiPMs. Journal of Instrumentation, 11(08), P08008-P08008. doi:10.1088/1748-0221/11/08/p0800

Exploring TOF Capabilities of PET Detector Blocks Based on Large Monolithic Crystals and Analog SiPMs

[EN] Monolithic scintillators are more frequently used in PET instrumentation due to their advantages in terms of accurate position estimation of the impinging gamma rays both planar and depth of interaction, their increased efficiency, and expected timing capabilities. Such timing performance has been studied when those blocks are coupled to digital photosensors showing an excellent timing resolution. In this work we study the timing behaviour of detectors composed by monolithic crystals and analog SiPMs read out by an ASIC. The scintillation light spreads across the crystal towards the photosensors, resulting in a high number of SiPMs and ASIC channels fired. This has been studied in relation with the Coincidence Timing Resolution (CTR). We have used LYSO monolithic blocks with dimensions of 50 x 50 x 15 mm(3) coupled to SiPM arrays (8 x 8 elements with 6 x 6 mm(2) area) which compose detectors suitable for clinical applications. While a CTR as good as 186 ps FWHM was achieved for a pair of 3 x 3 x 5 mm(3) LYSO crystals, when using the monolithic block and the SiPM arrays, a raw CTR over 1 ns was observed. An optimal timestamp assignment was studied as well as compensation methods for the time-skew and time-walk errors. This work describes all steps followed to improve the CTR. Eventually, an average detector time resolution of 497 ps FWHM was measured for the whole thick monolithic block. This improves to 380 ps FWHM for a central volume of interest near the photosensors. The timing dependency with the photon depth of interaction and planar position are also included.This project has received funding from 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.Lamprou, E.; González Martínez, AJ.; Sánchez Martínez, F.; Benlloch Baviera, JM. (2020). Exploring TOF Capabilities of PET Detector Blocks Based on Large Monolithic Crystals and Analog SiPMs. Physica Medica. 70:10-18. https://doi.org/10.1016/j.ejmp.2019.12.004101870Surti, S. (2014). Update on Time-of-Flight PET Imaging. Journal of Nuclear Medicine, 56(1), 98-105. doi:10.2967/jnumed.114.145029Spanoudaki, V. C., & Levin, C. S. (2010). Photo-Detectors for Time of Flight Positron Emission Tomography (ToF-PET). Sensors, 10(11), 10484-10505. doi:10.3390/s101110484Szczesniak, T., Moszynski, M., Swiderski, L., Nassalski, A., Lavoute, P., & Kapusta, M. (2009). Fast Photomultipliers for TOF PET. IEEE Transactions on Nuclear Science, 56(1), 173-181. doi:10.1109/tns.2008.2008992Renker, D. (2007). New trends on photodetectors. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 571(1-2), 1-6. doi:10.1016/j.nima.2006.10.016Kim, C. L., Wang, G.-C., & Dolinsky, S. (2009). Multi-Pixel Photon Counters for TOF PET Detector and Its Challenges. IEEE Transactions on Nuclear Science, 56(5), 2580-2585. doi:10.1109/tns.2009.2028075Moses, W. W. (2002). Current trends in scintillator detectors and materials. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 487(1-2), 123-128. doi:10.1016/s0168-9002(02)00955-5Gundacker, S., Auffray, E., Pauwels, K., & Lecoq, P. (2016). Measurement of intrinsic rise times for various L(Y)SO and LuAG scintillators with a general study of prompt photons to achieve 10 ps in TOF-PET. Physics in Medicine and Biology, 61(7), 2802-2837. doi:10.1088/0031-9155/61/7/2802Gundacker, S., Acerbi, F., Auffray, E., Ferri, A., Gola, A., Nemallapudi, M. V., … Lecoq, P. (2016). State of the art timing in TOF-PET detectors with LuAG, GAGG and L(Y)SO scintillators of various sizes coupled to FBK-SiPMs. Journal of Instrumentation, 11(08), P08008-P08008. doi:10.1088/1748-0221/11/08/p08008Surti, S., & Karp, J. S. (2016). Advances in time-of-flight PET. Physica Medica, 32(1), 12-22. doi:10.1016/j.ejmp.2015.12.007Gundacker, S., Knapitsch, A., Auffray, E., Jarron, P., Meyer, T., & Lecoq, P. (2014). Time resolution deterioration with increasing crystal length in a TOF-PET system. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 737, 92-100. doi:10.1016/j.nima.2013.11.025Marcinkowski, R., España, S., Van Holen, R., & Vandenberghe, S. (2014). Optimized light sharing for high-resolution TOF PET detector based on digital silicon photomultipliers. Physics in Medicine and Biology, 59(23), 7125-7139. doi:10.1088/0031-9155/59/23/7125González-Montoro, A., Sánchez, F., Martí, R., Hernández, L., Aguilar, A., Barberá, J., … González, A. J. (2018). Detector block performance based on a monolithic LYSO crystal using a novel signal multiplexing method. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 912, 372-377. doi:10.1016/j.nima.2017.10.098Xi, D., Xie, Q., Zhu, J., Lin, L., Niu, M., Xiao, P., … Kao, C.-M. (2012). Optimization of the SiPM Pixel Size for a Monolithic PET Detector. Physics Procedia, 37, 1497-1503. doi:10.1016/j.phpro.2012.04.101Gonzalez-Montoro A, Aguilar A, Canizares G, Conde P, Hernandez L, Vidal LF, et al. Performance Study of a Large Monolithic LYSO PET Detector With Accurate Photon DOI Using Retroreflector Layers. IEEE Trans Rad Plasma Med Sci. PP. 1-1. DOI: 10.1109/TRPMS.2017.2692819.Krishnamoorthy, S., Blankemeyer, E., Mollet, P., Surti, S., Van Holen, R., & Karp, J. S. (2018). Performance evaluation of the MOLECUBES β-CUBE—a high spatial resolution and high sensitivity small animal PET scanner utilizing monolithic LYSO scintillation detectors. Physics in Medicine & Biology, 63(15), 155013. doi:10.1088/1361-6560/aacec3González-Montoro, A., Sánchez, F., Bruyndonckx, P., Cañizares, G., Benlloch, J. M., & González, A. J. (2019). Novel method to measure the intrinsic spatial resolution in PET detectors based on monolithic crystals. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 920, 58-67. doi:10.1016/j.nima.2018.12.056Van Dam, H. T., Borghi, G., Seifert, S., & Schaart, D. R. (2013). Sub-200 ps CRT in monolithic scintillator PET detectors using digital SiPM arrays and maximum likelihood interaction time estimation. Physics in Medicine and Biology, 58(10), 3243-3257. doi:10.1088/0031-9155/58/10/3243Di Francesco A, Bugalho R, Oliveira L, Pacher L, Rivetti A, Rolo M, et al. TOFPET2: A high-performance ASIC for time and amplitude measurements of SiPM signals in time-of-flight applications. Journal of Instrumentation, vol. 11, no. 03, p. C03042.TOFPET2 ASIC Evaluation kit - Hardware User Guide (v1.2), v1.2, PETsys Electronics SA., 2018.Lamprou, E., Aguilar, A., González-Montoro, A., Monzó, J. M., Cañizares, G., Iranzo, S., … Benlloch, J. M. (2018). PET detector block with accurate 4D capabilities. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 912, 132-136. doi:10.1016/j.nima.2017.11.002Acerbi, F., & Gundacker, S. (2019). Understanding and simulating SiPMs. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 926, 16-35. doi:10.1016/j.nima.2018.11.118Schug D, Nadig V, Weissler B, Gebhardt P, Schulz V. Initial Measurements with the PETsys TOFPET2 ASIC Evaluation Kit and a Characterization of the ASIC TDC IEEE Trans Rad Plasma Med Sci. PP. 1-1. DOI: 10.1109/TRPMS.2018.2884564.Seifert, S., van Dam, H. T., Vinke, R., Dendooven, P., Lohner, H., Beekman, F. J., & Schaart, D. R. (2012). A Comprehensive Model to Predict the Timing Resolution of SiPM-Based Scintillation Detectors: Theory and Experimental Validation. IEEE Transactions on Nuclear Science, 59(1), 190-204. doi:10.1109/tns.2011.2179314Vinke R, Olcott PD, Cates JW, Levin CS. The lower timing resolution bound for scintillators with non-negligible optical photon transport time in time-of-flight PET. Phys. Med. Phys. Med. Biol. 59 6215. Phys Med Biol. 2014; 59(20): 6215–29.Gonzalez AJ, Sanchez F, Benlloch JM. 2018 Organ-Dedicated Molecular Imaging Systems. IEEE Trans Ratiat Plasma Med Sci. 2017; 2(5): 388–403

Calibration of Gamma Ray Impacts in Monolithic-Based Detectors Using Voronoi Diagrams

[EN] Molecular imaging systems, such as positron emission tomography (PET), use detectors providing energy and a 3-D interaction position of a gamma ray within a scintillation block. Monolithic crystals are becoming an alternative to crystal arrays in PET. However, calibration processes are required to correct for nonuniformities, mainly produced by the truncation of the scintillation light distribution at the edges. We propose a calibration method based on the Voronoi diagrams. We have used $50 \times 50 \times 15$ mm(3) LYSO blocks coupled to a $12\times 12$ SiPMs array. We have first studied two different interpolation algorithms: 1) weighted average method (WAM) and 2) natural neighbor (NN). We have compared them with an existing calibration based on 1-D monomials. Here, the crystal was laterally black painted and a retroreflector (RR) layer added to the entrance face. The NN exhibited the best results in terms of XY impact position, depth of Interaction, and energy, allowing us to calibrate the whole scintillation volume. Later, the NN interpolation has been tested against different crystal surface treatments, allowing always to correct edge effects. Best energy resolutions were observed when using the reflective layers (12%-14%). However, better linearity was observed with the treatments using black paint. In particular, we obtained the best overall performance when lateral black paint is combined with the RR.This work was supported in part by the European Research Council through the European Union's Horizon 2020 Research and Innovation Program under Grant 695536, and in part by the Spanish Ministerio de Economia, Industria y Competitividad under Grant TEC2016-79884-C2-1-R.Freire, M.; Gonzalez-Montoro, A.; Sánchez Martínez, F.; Benlloch Baviera, JM.; González Martínez, AJ. (2020). Calibration of Gamma Ray Impacts in Monolithic-Based Detectors Using Voronoi Diagrams. IEEE Transactions on Radiation and Plasma Medical Sciences. 4(3):350-360. https://doi.org/10.1109/TRPMS.2019.2947716S3503604

Novel method to measure the intrinsic spatial resolution in PET detectors based on monolithic crystals

[EN] The main aim of this work is to provide a method to retrieve the intrinsic spatial resolution of a gamma-ray detector block based on monolithic crystals within an assembled scanner. This method consists on a discrimination of the data using a software collimation process. The results are compared with an alternative method of separating two detector blocks far enough to produce a "virtual" source collimation due to the geometric constraints on the allowed coincidence event angles. A theoretical model has been deduced to fit the measured light distribution profiles, allowing estimating the detector intrinsic spatial resolution. The detector intrinsic spatial resolution is expected to follow a Gaussian distribution and the positron-emitter source shape, given the small size of a Na-22 source with 0.25 mm in diameter, can be assumed to follow a Lorentzian profile. However, the collimation of the data modifies the source shape that is no longer a pure Lorentzian distribution. Therefore, the model is based on the convolution of a Gaussian shaped distribution (contribution of the detector) and a modified Lorentzian distribution (contribution of the collimated source profile) that takes into account the collimation effect. Three LYSO crystals geometries have been studied in the present work, namely a 10 mm thick trapezoidal monolithic block, and two rectangular monolithic blocks with thicknesses of 15 mm and 20 mm, respectively. All the blocks have size dimensions of 50 mm x 50 mm. The experimental results yielded an intrinsic detector spatial resolution of 0.64 +/- 0.02 mm, 0.82 +/- 0.02 and 1.07 +/- 0.03 mm, for the 10 mm, 15 mm and 20 mm thick blocks, respectively, when the source was placed at the center of the detector. The detector intrinsic spatial resolution was moreover evaluated across one of the axis of each crystal. These values worsen to an average value of 0.68 +/- 0.04 mm, 0.90 +/- 0.14 and 1.29 +/- 0.19 mm, respectively, when the whole crystal size is considered, as expected. These tests show an accurate method to determine the intrinsic spatial resolution of monolithic-based detector blocks, once assembled in the PET system.This project has received funding from the European Research Council, Spain (ERC) under the European Union's Horizon 2020 research and innovation program (grant agreement No 695536). It has also been supported by the EU, Spain Grant 603002 under the FP7 program, and 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, Spain.González, A.; Sanchez, F.; Bruyndonckx, P.; Cañizares-Ledo, G.; Benlloch Baviera, JM.; González Martínez, AJ. (2019). Novel method to measure the intrinsic spatial resolution in PET detectors based on monolithic crystals. Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment. 920:58-67. https://doi.org/10.1016/j.nima.2018.12.056S586792

Progress report on the MEDAMI 2019 and CTR research at the DMIL in i3M

[EN] This contribution reports on the recently held MEDAMI 2019 workshop in Valencia (15-17th May 2019). This workshop is about advanced molecular imaging and the main topic of this last edition was Imaging in Immunotherapy. Around 70 attenders met together during three days. This meeting made it possible to join medical doctors and instrumentalists. In MEDAMI 2019 it was exposed the new immunotherapies from a clinical and research point of view. It was shown the already observed improvements when using these therapies. At the same time, we heard about the difficulties and limitations of current molecular imaging in this particular field. It was clear that improvements in system sensitivity and resolution are demanded. Timing information can be utilized in different ways to improve the image quality in PET systems. Precise Coincidence Time Resolution (CTR) improves the signal-to-noise ratio and, therefore, the image contrast, allowing for instance to distinguish low uptake tumors, multicentric lesions, or tumor heterogeneity, to name but a few. Both high time resolution and angular coverage in a PET system can improve the effective sensitivity. An example of a system benchmarking the timing resolution is the Siemens Biograph Vision with 214 ps FWHM, enhancing the detectability. The Explorer total-body PET from UC Davis improves the system sensitivity by having a 2 meters long PET scanner. Deep investigations, from different research groups, are being carried out to further push the limits of timing resolution. This work also describes some of the projects on high timing performance that are being carried out at the Detector for Molecular Imaging Lab (DMIL) at the Institute for Instrumentation in Molecular Imaging (i3M) in Valencia. The DMIL group has extensively worked on detectors and implementation of PET systems enabling the use of accurate timing information. In this progress report we describe the results obtained at the DMIL regarding timing determination in gamma-ray detectors both based on monolithic and pixelated crystals. Although with 15 min thick LYSO blocks it was tough to obtain values of CTR below 500 ps when using analog SiPMs and ASIC-based readout, this was improved down to 250 ps if small 3 mm size and 6 mm height pixels under the one-to-one coupling approach were enabled. This type of approach, the one-to-one coupling, seems to benefit from the light collection in a single photosensor element and, therefore, to improve the timing properties. Monolithic blocks offer, on the contrary, advantages such as photon depth of interaction. In order to separate Compton and photoelectric events we have thought of a detector block design with a high aspect ratio, using LYSO crystals of 51 mm size vs. 3 mm thickness, read-out by the four lateral sides. We have demonstrated the possibility to reach below 2 mm FWHM spatial resolution with an energy resolution of 12%.The DMIL work presented in this paper has received funding from 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. The author would like to thank all current and former members of the DMIL at i3M for their continuous contributions to this work.González Martínez, AJ.; Barrio, J.; Lamprou, E.; Ilisie, V.; Sánchez Martínez, F.; Benlloch Baviera, JM. (2020). Progress report on the MEDAMI 2019 and CTR research at the DMIL in i3M. Il Nuovo cimento C. 43(1):1-10. https://doi.org/10.1393/ncc/i2020-20005-8S11043

High resolution and sensitivity gamma camera with active septa. A first Monte Carlo study

[EN] Gamma cameras are of great interest due to their high potential in the field of Nuclear Medicine Imaging. They allow for an early diagnosis of reduced size tumors, and also for a wide variety of preclinical studies with the aim of designing more effective treatments against cancer. In this work we propose a significantly improved multi-pinhole collimator gamma camera and perform a first Monte Carlo analysis of its characteristics. Maintaining the configuration of a multi-pinhole collimator with a high degree of overlapping (thus with a high sensitivity), we add a new element, an active septa, that besides acting as a collimator, is able to measure the impact coordinates of the incident photon. This way one is able to unambiguously identify through which pinhole any gamma ray passes before being detected. The result is a high sensitivity and resolution multi-pinhole gamma camera with an arbitrarily large field of view. As a consequence, the final reconstructed image does not suffer from the undesired artifacts or truncation associated to the multiplexing phenomenon. In this study we focus on the development of a system able to visualize in 3D tumors, nodes and metastasis in real time in the operating room with very low dose. We also briefly analyse and propose a novel design for a Single Photon Emission Computed Tomography system.This project has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (Grant Agreement No. 695536). This work was supported in part by the Spanish Government Grants Generalitat Valenciana, APOSTD/2019/086 and TEC2016-79884-C2 and RTC-2016-5186-1.Ilisie, V.; Moliner, L.; Oliver-Gil, S.; Sánchez Martínez, F.; González Martínez, AJ.; Seimetz, M.; Rodríguez Álvarez, MJ.... (2019). High resolution and sensitivity gamma camera with active septa. A first Monte Carlo study. Scientific Reports. 9:1-9. https://doi.org/10.1038/s41598-019-54934-0S199Mok, G. S. P., Tsui, B. M. W. & Beekman, F. J. The effects of object activity distribution on multiplexing multi-pinhole SPECT. Phys. Med. Biol. 56, 2635–2650 (2011).Johnson, C., Shokouhi, S. & Peterson, T. E. Reducing Multiplexing artifacts in Multi-Pinhole SPECT with a Stacked Silicon-Germanium System: a Simulation Study. IEEE Trans Med Imaging. 33(12), 2342–2351 (2014).Mok, G. S. P., Wang, Y. & Tsui, B. M. W. Quantification of the Multiplexing Effects in Multi-Pinhole Small Animal SPECT: A Simulation Study. IEEE Trans Nucl Sci. 56(5), 2636–2643 (2009).Vunckx, K., Suetens, P. & Nuyts, J. Effect of Overlapping Projections on Reconstruction Image Quality in Multipinhole SPECT. IEEE Transactions on Medical Imaging. 27(7) (2008).Ivashchenko, O. et al. Quarter-Millimeter-Resolution Molecular Mouse Imaging with U-SPECT+. Mol Imaging. 2014. 13 (2014).Gal, O. et al. Development of a portable gamma camera with coded apertura. Nuclear Instruments and Methods in Phys. Res. A. 563, 233–237 (2006).Accorsi, R., Gasparini, F. & Lanza, R. C. A Coded Aperture for High-Resolution Nuclear Medicine Planar Imaging With a Conventional Anger Camera: Experimental Results. IEEE Transactions on Nuclear Science. 48, 2411–2417 (2001).Fuji, H. et al. Optimization of Coded Aperture Radioscintigraphy for Sentinel Lymph Node Mapping. Mol. Imaging Biol. 14, 173–182 (2012).Accorsi, R., Gasparini, F. & Lanza, R. C. Optimal coded aperture patterns for improved SNR in nuclear medicine imaging. Nucl. Instrum. Methods Phys. Res. A. 474, 273–284 (2001).Lee, T. & Lee, W. Portable Active Collimation Imager Using URA Patterned Scintillator. IEEE Transactions on Nuclear Science. 61, 654–662 (2014).Lee, T. & Lee, W. A cubic gamma camera with an active collimator. Applied Radiation and Isotopes. 90, 102–108 (2014).Accorsi, R. & Lanza, R. C. Near-field artifact reduction in coded aperture imaging. Appl. Opt. 40, 4697–4705 (2001).Ilisie, V., Sánchez, F., González, A. J. & Benlloch, J. M. Dispositivo Para la Detección de Rayos Gamma con Tabiques Activos (Device for Gamma Ray Detection with Active Septa), Patent application Ref. P201831058/PT-018004.González, A. J. et al. Detector block based on arrays of 144 SiPMs and monolithic scintillators: A performance study. Nuclear Instruments and Methods in Physics Research A. 787, 42–45 (2015).Pani, R. et al. Preliminary evaluation of a monolithic detector module for integrated PET/MRI scanner with high spatial resolution. JINST. 10, C06006 (2015).Pani, R. et al. Continuous DOI determination by Gaussian modelling of linear and non-linear scintillation light distributions. Proc. IEEE NSS-MIC. 3386–3389 (2011).Shepp, L. A. & Vardi, Y. Maximum likelihood reconstruction for emission tomography. IEEE Transactions on Medical Imaging. 2, 113 (1982).Hudson, H. M. & Larkin, R. S. Accelerated Image Reconstruction Using Ordered Subsets of projection Data. IEEE Transactions on Medical Imaging. 13, 601 (1994).Reader, A. J. et al. Accelerated list-mode EM algorithm. IEEE Transactions on Nuclear Science. 49, 42 (2002).Rahmim, A., Ruth, T. & Sossi, V. Study of a convergent subsetized list-mode EM reconstruction algorithm. FILTR SEP. 6. 3978–3982. 6, 10.1109 (2004).Siddon, R. L. Fast calculation of the exact radiological path for a three-dimensional CT array. Medical Physics. 12, 252 (1985).Sundermann, E., Jacobs, F., Christiaens, M., De Sutter, B. & Lemahieu, I. A Fast Algorithm to Calculate the Exact Radiological Path Through a Pixel Or Voxel Space. Journal of Computing and Information Technology. 6 (1998).Reader, A. J. et al. One-pass list-mode EM algorithm for high-resolution 3-D PET image reconstruction into large arrays. IEEE Transactions on Nuclear Science. 49(3), 693–699 (2002).Agostinelli, S. et al. Geant4 - a simulation toolkit. Nuclear Instruments and Methods in Physics Research A. 506, 250–303 (2003).Jan, S. et al. GATE - Geant4 Application for Tomographic Emission: a simulation toolkit for PET and SPECT. Phys. Med. Biol. 49(19), 4543–4561 (2004)

Characterization of a High-Aspect Ratio Detector With Lateral Sides Readout for Compton PET

This work was supported by the European Research Council through the European Union's Horizon 2020 Research and Innovation Program under Grant 695536.Barrio, J.; Cucarella, N.; González Martínez, AJ.; Freire, M.; Ilisie, V.; Benlloch Baviera, JM. (2020). Characterization of a High-Aspect Ratio Detector With Lateral Sides Readout for Compton PET. IEEE Transactions on Radiation and Plasma Medical Sciences. 4(5):546-554. https://doi.org/10.1109/TRPMS.2020.3006862S5465544

Goat Milk Nutritional Quality Software-Automatized Individual Curve Model Fitting, Shape Parameters Calculation and Bayesian Flexibility Criteria Comparison

SPSS syntax was described to evaluate the individual performance of 49 linear and non-linear models to fit the milk component evolution curve of 159 Murciano-Granadina does selected for genotyping analyses. Peak and persistence for protein, fat, dry matter, lactose, and somatic cell counts were evaluated using 3107 controls (3.91 ± 2.01 average lactations/goat). Best-fit (adjusted R 2 ) values (0.548, 0.374, 0.429, and 0.624 for protein, fat, dry matter, and lactose content, respectively) were reached by the five-parameter logarithmic model of Ali and Schaeffer (ALISCH), and for the three-parameter model of parabolic yield-density (PARYLDENS) for somatic cell counts (0.481). Cross-validation was performed using the Minimum Mean-Square Error (MMSE). Model comparison was performed using Residual Sum of Squares (RSS), Mean-Squared Prediction Error (MSPE), adjusted R 2 and its standard deviation (SD), Akaike (AIC), corrected Akaike (AICc), and Bayesian information criteria (BIC). The adjusted R 2 SD across individuals was around 0.2 for all models. Thirty-nine models successfully fitted the individual lactation curve for all components. Parametric and computational complexity promote variability-capturing properties, while model flexibility does not significantly (p > 0.05) improve the predictive and explanatory potential. Conclusively, ALISCH and PARYLDENS can be used to study goat milk composition genetic variability as trustable evaluation models to face future challenges of the goat dairy industry