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Recently, dual-modality systems have been developed, aimed to correlate anatomical and functional information, improving disease localization and helping oncological or surgical treatments. 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. © 2018 Elsevier Ltd

188 Re is a beta and gamma emitter used in metabolic radiotherapy. SCINTIRAD is a multidisciplinary collaboration that aims at determining the radio-response of 188 Re in cells “in vitro” and the biodistribution in different organs of mice “in vivo”, and studying the therapeutic effect on liver and other tumours induced in mice. Several tumour cell lines have been treated “in vitro” with a 188 Re solution. The dosimetry of 188 Re used to target the different lines of cancer cells has been evaluated using GEANT4, and preliminary results are presented. Studies to optimize the imaging of 188 Re “in vivo” have also continued, including the characterization of H8500 Flat Panel PMT and of LaBr 3 crystals, and the development of dedicated electronics.

In this paper the response in term of pulse height linearity of two Hamamatsu photomultipliers is investigated, when coupled to a LaBr 3 :Ce scintillation crystal. The two photodetectors have high quantum efficiency and in particular 30% for R6231-01 and 42% for R7600-200 tube. The substantial difference is in the dynode structure, linear focused and metal channel for R6231 and R7600 respectively. In this work in order to verify the non-linearity effects on the pulse height distribution, due principally to the high and fast light production of LaBr 3 :Ce scintillator, we propose a ‘peak by peak’ procedure to calibrate the pulse height distribution. Utilizing a specific fragmentation of the calibration curve in subsets, the calculated energy values are very similar for both PMTs. This result confirmed the potentiality of the procedure to highlight the non-linearity effects on pulse height distribution.

Recently scintillating crystals with high light yield coupled to photodetectors with high quantum efficiency have been opening a new way to make gamma cameras with superior performances based on continuous crystals. In this work we propose the analysis of a gamma camera based on a continuous LaBr3:Ce crystal coupled to a multi-anodes photomultiplier tube (MA-PMT). In particular we take into account four detector configurations, different in crystal thicknesses and assembling. We utilize a new position algorithm to reduce the position non linearity affecting intrinsic spatial resolution of small FoV gamma cameras when standard Anger algorithm is applied. The experimental data are obtained scanning the detectors with 0.4 mm collimated 99 m Tc source, at 1.5 mm step. An improvement in position linearity and spatial resolution of about a factor two is obtained with the new algorithm. The best values in terms of spatial resolution were 0.90 mm, 0.95 mm and 1.80 mm for integral assembled, 4.0 mm thick and 10 mm thick LaBr3:Ce crystal respectively.

In this work we propose an analysis of a novel Low Energy (LE) parallel hole collimator for high resolution SPET applications. The tested prototype, realized jointly with Nuclear Fields, is a lead parallel hole collimator with 1.0 mm hexagonal hole, 18 mm length, 0.2 mm septa and 10x10 cm2 of useful detection area. It was planned to match the high spatial resolution performances of a compact gamma camera based on LaBr3(Ce) continuous scintillation crystal. The imaging performance of this prototype is compared with a tungsten pinhole collimator (1.0 mm diameter) and with a couple of 1.5 mm parallel hole collimators, 22 mm and 40 mm length with 0.2 mm septa respectively. All the collimators were individually coupled to a scintillation gamma camera based on LaBr3(Ce) continuous crystal and multi anode PMT Hamamatsu H8500. The high intrinsic spatial resolution of the crystal enhances the response of collimators at short source-to-collimator distance –SCD overcoming problems in alignment with the collimator pattern. Spatial resolution and sensitivity were evaluated by scanning the detector field of view at different SCD using a Co57 point source. The parallel hole prototype showed SR better than pinhole with 28 mm FoV. In term of sensitivity, it showed values greater than pinhole one at FoV larger than 2.4 cm. In comparison with LEHR parallel hole collimators, the prototype carried out better SR values at SCD lower than 20 mm with two times more sensitivity. Moreover, the overall SR improved of 20% with respect to the LEGP one at all SCD, with only 35% loss of sensitivity. The collimator prototype seemed complementary with the use of pinhole one and in addition when coupled to the compact LaBr3(Ce) gamma camera can allow a very attractive trade-off between spatial resolution, sensitivity and detection area for radionuclide molecular imaging applications.

The new PMT generation with very high quantum efficiency is very attractive for their potential to improve energy resolution, in particular for applications involving new scintillation crystals with high light yield. Furthermore recent development of new devices, like silicon photomultipliers (SiPMs), with high gain and quantum efficiency have raised the competition between silicon and standard photomultiplier device in particular for application where high energy resolution may improve the imaging response of the detector. Hamamatsu has recently developed a new prototype PMT R7600-200 with an Ultra BiAlkali (UBA) photocathode (QE=42%). To evaluate the improvement, we compared the energy resolution obtained by R7600-200 PMT with ones from a standard R7600 PMT (QE=22%); the results from both PMTs was obtained with a standard and a tapered divider circuit respectively. We compared also the data from a MA-PMT H8500 and from a PMT R6231, representing a gold standard. A LaBr3:Ce scintillator crystal (½” diam. x ½” thick) was coupled to all PMTs. Preliminary results show an energy resolution improvement with UBA photocathode of about 30% @122keV with respect to R7600, close to what expected from the higher quantum efficiency (40%). On the contrary they agree with ones from R6231 PMT, thought its lower QE. This result is probably due to the different collection efficiency of first dynode stage related to different dynode structure of tubes. Furthermore an energy resolution improvement smaller than expected resulted from H8500 MA-PMT. Thought the same dynode structure, this result is not well understood and it could probably due to the larger size of MAPMT photocathode, involving a better light collection. In any case, the improvement of 30% between UBA e No-UBA PMT is not in agreement with the expected one (20%), considering the intrinsic energy resolution of LaBr3:Ce (4.4%@ 140 keV). This behavior is not well explained at moment and is matter of next investigations.

The availability of LaBr3:Ce crystals from St. Gobain has started various investigations in the field of medical imaging, in particular in PET, SPECT and Compton camera systems. At present LaBr3:Ce crystals are available in a continuous shape covering up to 10×10 cm2 with a thickness of 1 cm, in contrast, serious concerns are arising in pixellated manufacturing. With the aim of verifying the potentials introduced by LaBr3:Ce for SPET imaging, two small γ cameras based on Anger camera principle have been assembled and imaging performances were compared. Two crystals of LaBr3:Ce and NaI(Tl) with the same detection area (5×5 cm2) and thickness of 5 and 1.5 mm, respectively were been integrally assembled with a H8500 Hamamatsu flat panel PMT. Through the thicker crystal, the LaBr3:Ce camera showed superior imaging and detection performances at 140 keV compared with the NaI(Tl) one, with 0.9 mm FWHM intrinsic spatial resolution, 8% FWHM energy resolution and 80% intrinsic detection efficiency.

Scintirad is an interdisciplinary research program that studies novel translational radiopharmaceuticals for cancer diagnosis and therapy. Scintirad employs methods of the Nuclear Medicine applied to small animals and develops new instrumentation for high resolution imaging. The first part of this report describes research programs, results and future plans, while the second part, entitled “who we are”, offers an overview of the role of involved teams and facilities.

The principal limiting factor in the clinical acceptance of scintimammography is certainly its low sensitivity for cancers sized

188Re is a beta- (Emax = 2.12 MeV) and gamma (155 keV) emitter. Since its chemistry is similar to that of the largely employed tracer, 99mTc, molecules of hyaluronic acid (HA) have been labelled with 188Re to produce a target specific radiopharmaceutical. The radiolabeled compound, i.v. injected in healthy mice, is able to accumulate into the liver after a few minutes. To study the effect of metabolic radiotherapy in mice, we have built a small gamma camera based on a matrix of YAP:Ce crystals, with 0.6x0.6x10 mm**3 pixels, read out by a R2486 Hamamatsu PSPMT. A high-sensitivity 20 mm thick lead parallel-hole collimator, with hole diameter 1.5 mm and septa of 0.18 mm, is placed in front of the YAP matrix. Preliminary results obtained with various phantoms containing a solution of 188Re and with C57 black mice injected with the 188Re-HA solution are presented. To increase the space resolution and to obtain two orthogonal projections simultaneously we are building in parallel two new cameras to be positioned at 90 degrees. They use a CsI(Tl) matrix with 1x1x5 mm**3 pixels read out by H8500 Hamamatsu Flat panel PMT., Comment: 6 pages, 8 figs. To appear in Nucl. Phys. B (PS), proc. of Innovative Particle and Radiation Detectors, Siena, 23-26 May 2004

The introduction of Lanthanum Bromide crystal, characterized by a fast and high light emission, offers the possibility to improve both imaging spatial resolution and energy resolution in SPECT in the 80-300 kev energy range, without compromising detection efficiency. The expected performances may be limited if the crystal is used with a multi-anode PMT with Position Sensitive response due to the wide differences in the segmented anode pad gains, ranging from 2:1 to 10:1, . These characteristics may strongly deteriorate the overall energy resolution and, consequently, impair the detector imaging capability. For this reason, a 256 independent channel electronic read out was developed, based on an FPGA control, to individually read the charge on each anode. The electronics features a very low electronic noise ( < 1%) and a wide dynamic range. The readout electronics was used to build a gamma camera based on a single 100 mm × 100 mm continuous LaBr3:Ce crystal coupled to a 2 × 2 array SBA photocatode (38{%} QE) Hamamatsu H8500. An offline calibration procedure is also shown in order to compensate the anode gain variation and to exploit the LaBr3:Ce capabilities, obtaining on the whole detection area an 8.0-8.5{%} energy resolution at 140 kev. The high energy resolution performances of this gamma camera permitted to discriminate emissions from two different isotope ( Tc99m and Co57) with very close photon energy (140 and 122 kev respectively). This capability can be used to provide the gamma image with references coming from Co 57 point sources (marker) fixed at known positions. These results confirm the LaBr3:Ce crystals as one of the most interesting for all single photon emission applications. © 2013 IOP Publishing Ltd and Sissa Medialab srl.

This paper reports on the tests of a low-noise, multi-channel readout integrated circuit used as a readout electronic front-end for a diamond multi-pixel dosimeter. The system is developed for dose distribution measurement in radiotherapy applications. The first 10-channel prototype chip was designed and fabricated in a 0.18 um CMOS process. Every channel includes a charge integrator with a 10 pF capacitor and a double slope A/D converter. The diamond multi-pixel detector, based on CVD synthetic single crystal diamond Schottky diodes, is made by a 3 × 3 sensor matrix. The overall device has been tested under irradiation with 6 MeV radio therapeutic photon beams at the Policlinico ''Tor Vergata'' (PTV) hospital. Measurements show a 20 fA RMS leakage current from the front-end input stage and a negligible dark current from the diamond detector, a stable temporal response and a good linear behaviour as a function of both dose and dose rate. These characteristics were common to each tested channel. © 2013 IOP Publishing Ltd and Sissa Medialab srl.

The bimodal diagnostic systems like ultrasound/scintigraphic ones have the benefit of providing both morphological and physiological information. In the case in which it intends to develop a compact bimodal probe it is important that, as the readout electronics are doubled, the acquisition system is the most compact possible. In this paper we present the characterization and preliminary measurements on a multi-channel readout ASIC for PSPMTs. The chip is equipped with 32 readout channels, as different works show that single channel readout allows to exploit the performances of a gamma detector, especially for linearity. Each single channel readout is composed by a variable capacitor CSA, a sample&hold and a variable gain amplifier (VGA). The possibility to change the gain of the amplifier allows to compensate for the differences in gain of the anodes of the PSPMT, while the possibility of changing the integrator capacitor allows to adapt the input dynamic of the chip depending on the PMT used (BA or SBA photocatode) and on the scintillation crystal coupled to the PMT itself. The preliminary measurements show that a 200 kHz maximum sampling rate is achievable, with 1 V input dynamic and an overall linearity of the whole channel with respect to the input charge impulse of than 2%. To validate the performances of the ASIC different operative measurement was made in two configurations: with a single chip and two R11265-M16 PMTs, and, parallelizing two chips with a single PMT H8500. The tubes were coupled with scintillation crystals with different response speeds, from CsI to LaBr3.

In this work, we present a mean square estimation (MSE) based algorithm to calculate the position of a scintillation event within the crystal of a gamma camera dedicated to single photon imaging applications. The performances analysis takes into account pixilated and continuous shape configuration crystals, coupled to an Hamamatsu H8500C multi-anodes PMT (MA-PMT). The readout electronics used for readout has 64-independent channels each reading simultaneously the 64 anodes of the MA-PMT. An array of NaI(Tl) scintillation crystal with 2.0 mm pitch, one of CsI(Tl) with 1.6 mm pitch and one of YAP with 2.0 mm pixel size are taken into account. In addition, a continuous LaBr 3(Ce) crystal coupled to an Hamamatsu H8500C-Mod8 MA-PMT equipped with a super-bialkali photocathode (38% QE at 380 nm) was analyzed. Position linearity and spatial resolution analyzed with collimated (for continuous crystal) and uncollimated (for pixilated crystal) Co57 radioactive source and the scintillation points are calculated both with MSE and with a standard center of gravity (CoG) algorithm. The MSE algorithm improves spatial resolution and expands the useful field of view (UFOV) of the gamma camera that nearly reaches the size of the photocathode area thus showing a great advantage with respect to the CoG algorithm. © 2010 Elsevier B.V. All rights reserved.

We present a mean square estimation (MSE) based algorithm for position calculation of a scintillation gamma cam­era dedicated to single photon imaging. The photodetector consist of a 2×2 array of Hamamatsu H8500C-Mod8 segmented-anodes PMT (10×10 cm detection area)coupled to an array of NaI(Tl) scintillation crystals with 1.8 mm pixel size. Phototubes are read out by a 256-independent channels electronics each reading simultaneously all the anodes of the MA-PMT. We analyzed position linearity and spatial resolution where the scintillation points are calculated both with MSE and with a standard center of gravity (CoG) algorithm, and with particular attention to the crystal edge and between tubes. The MSE algorithm improves the pixel identification and the linearity, and expands the useful field of view (UFOV) up to the whole detection area of the gamma cameras. In conclusion, MSE showing a greater advantage with respect to the CoG algorithm.

The increasing demand of sophisticated devices for Medical Imaging, with submillimeter spatial resolution and high detection efficiency, motivates an in-depth study of detectors able to fulfill these requirements. In particular for Single Photon Emission Tomography applications, the on-going development of large LaBr3:Ce crystals makes very attractive their use as a system of gamma imaging. Single crystals can overcome the limitation in term of spatial resolution related to pixel size in scintillation arrays, once the problems of limited position linearity and image size are solved. In this work we use GEANT4 simulations in order to model different configurations based on LaBr3:Ce crystals coupled to a Hamamatsu H8500 Multi Anode Photomultiplier. The position linearity, the spatial and energy resolutions obtainable from optimum photodetection conditions are investigated. The values obtained by the Monte Carlo simulations are compared to the experimental results and found to be in good agreement with them upon tuning of some parameters.

Knowledge of the Depth-Of-Interaction (DOI) in detector is crucial for small ring diameter PET scanner but it is also very important for single photon emission imaging, in particular for applications where very high spatial resolution is required and position distortions caused by slant collimators can strongly affect the final response of the 3D reconstructed image. In addition the DOI determination at 140 keV is the most critical due to thinner crystal thickness and the lower number of scintillation light photons. Continuous scintillation crystals are in principle the most suitable for continuous DOI determination based on the measurements of light width of cones generated at each gamma ray interaction. In this work we propose an analysis based on a Monte Carlo GEANT4 studies and on experimental measurements at 140 keV performed on a small LaBr3:Ce continuous crystal coupled to latest multi-anode PMT Hamamatsu H8500-MOD8 series equipped with super Bialkali photocathode (SBA). The basic idea of this work is that the high light output of LaBr 3 :Ce joint with SBA photodetector can reduces statistical uncertainties related to the light distribution spread determination. Furthermore it can be crucial with a more precise measurement of scintillation light distribution from the 8×8 anode array of MAPMT. Measurements and simulation confirm that light distribution spread (SD) is related to DOI, with a DOI resolution of about 2.0-2.2 mm (Monte Carlo) and 2.8-3.0 mm experimental at 140 keV. In addition, we shown how the selection in SD window provide a 10% of spatial resolution improvement, down to (0.85±0.03) mm, for a LaBr 3 (Ce) continuous crystal coupled to the new photodetector H8500-MOD8. This method can open the possibility to build a high-sensitivity detector with DOI capability useful for gamma-ray imaging application.

The use of position sensitive multianode PMTs requests the reading of a large number of channels at the same time, in order to correct the anode gain variations that are found in these devices.

The paper illustrates two different Artificial Neural Networks (ANN) architectures for electric Short-Term Load Forecasting (STLF). Two multi-layer perceptron ANN using the back-propagation learning algorithm have been implemented which provide different, although complementary, forecasting approaches (static and dynamic). In order to test the potentialities of the architectures implemented, the ANN have been applied to the Short-Term Forecasting of Italian hourly electric load. The importance of this load (peak demands up to about 38 000 MW) requires tools for STLF which must be as more accurate and precise as possible. This fact has imposed the adoprequires tools for STLF which must be as more accurate and precise as possible. This fact has imposed the adoption of some algorithmic enhancements to the basic back-propagation algorithm formulation. Since an adequate formulation of the influence exerted on hourly electric load by the main meteorological and climatic factors is not known at present, the data set used for ANN training phase has concerned only historical series of electric hourly demand. The paper illustrates the two ANN architectures as well as the computational platforms used for implementation. Finally, some results obtained from the application of the two ANN to the short-term forecasting of Italian electric load relevant to three different weeks of the year 1993 are comparatively reported.