Gamma-ray sources imaging and test-beam results with MACACO III Compton camera

Hadron therapy is a radiotherapy modality which offers a precise energy deposition to the tumors and a dose reduction to healthy tissue as compared to conventional methods. However, methods for real-time monitoring are required to ensure that the radiation dose is deposited on the target. The IRIS group of IFIC-Valencia developed a Compton camera prototype for this purpose, intending to image the Prompt Gammas emitted by the tissue during irradiation. The system detectors are composed of Lanthanum (III) bromide scintillator crystals coupled to silicon photomultipliers. After an initial characterization in the laboratory, in order to assess the system capabilities for future experiments in proton therapy centers, different tests were carried out in two facilities: PARTREC (Groningen, The Netherlands) and the CNA cyclotron (Sevilla, Spain). Characterization studies performed at PARTREC indicated that the detectors linearity was improved with respect to the previous version and an energy resolution of 5.2 % FWHM at 511 keV was achieved. Moreover, the imaging capabilities of the system were evaluated with a line source of 68Ge and a point-like source of 241Am-9Be. Images at 4.439 MeV were obtained from irradiation of a graphite target with an 18 MeV proton beam at CNA, to perform a study of the system potential to detect shifts at different intensities. In this sense, the system was able to distinguish 1 mm variations in the target position at different beam current intensities for measurement times of 1800 and 600 s.</p

Gamma-ray sources imaging and test-beam results with MACACO III Compton camera

Hadron therapy is a radiotherapy modality which offers a precise energy deposition to the tumors and a dose reduction to healthy tissue as compared to conventional methods. However, methods for real-time monitoring are required to ensure that the radiation dose is deposited on the target. The IRIS group of IFIC-Valencia developed a Compton camera prototype for this purpose, intending to image the Prompt Gammas emitted by the tissue during irradiation. The system detectors are composed of Lanthanum (III) bromide scintillator crystals coupled to silicon photomultipliers. After an initial characterization in the laboratory, in order to assess the system capabilities for future experiments in proton therapy centers, different tests were carried out in two facilities: PARTREC (Groningen, The Netherlands) and the CNA cyclotron (Sevilla, Spain). Characterization studies performed at PARTREC indicated that the detectors linearity was improved with respect to the previous version and an energy resolution of 5.2 % FWHM at 511 keV was achieved. Moreover, the imaging capabilities of the system were evaluated with a line source of 68Ge and a point-like source of 241Am-9Be. Images at 4.439 MeV were obtained from irradiation of a graphite target with an 18 MeV proton beam at CNA, to perform a study of the system potential to detect shifts at different intensities. In this sense, the system was able to distinguish 1 mm variations in the target position at different beam current intensities for measurement times of 1800 and 600 s.</p

Experimental characterization and test-beam results of MACACO III Compton camera

The IRIS group at IFIC-Valencia is developing a Compton camera prototype with the aim of applying it in hadron therapy treatment monitoring. Recently, a third version of the prototype MACACO (Medical Applications CompAct COmpton camera) has been built. The system is composed of three Lanthanum (III) bromide scintillator crystals coupled to silicon photomultipliers. To improve its performance for the final application, several detectors are tested, two different silicon photomultipliers (25 and 50 um) have been chosen as possible candidates. The 25 up photodetector provided better performance in therms of dynamic range, energy resolution (5.2/ FWHM at 511 keV) and stability with temperature variations. MACACO III has also been tested in the CNA cyclotron (Seville) with 18 MeV proton beam to produce 4.439 MeV gamma rays. Data have been acquired with a graphite target in five different positions at 2.5 nA nominal beam intensity. Images with 4.439 MeV photons have been reconstructed, demonstrating the system capability to reconstruct images at energies relevant for hadron therapy. Moreover, the system has been able to distinguish 1mm displacements in the target position

New probe for the improvement of the Spatial Resolution in total-body PET (PROScRiPT)

In recent decades, PET scanners have been widely used for diagnosis and treatment monitoring in nuclear medicine. The continuous effort of the scientific community has led to improvements in scanner performance. Total-body PET is one of the latest upgrades in PET scanners. These kinds of scanners are able to scan the whole body of the patient with a single bed position, since the scanner tube is long enough for the patient to fit inside. While these scanners show unprecedented efficiency and extended field-of-view, a drawback is their low spatial resolution compared to dedicated scanners. In order to improve the spatial resolution of specific areas when measuring with a total-body PET scanner, the IRIS group at IFIC-Valencia is developing a probe. The proposed setup of the probe contains a monolithic scintillation crystal and a SiPM. The signal of the probe is read out by a TOFPET2 ASIC from PETsys, which has shown good performance for PET in terms of spatial and time resolutions. Furthermore, the PETsys technology generates a trigger signal that will be used to time synchronise the probe and the scanner. The proof-of-concept of the probe will be tested in a Preclinical Super Argus PET/CT scanner for small animals located at IFIC. Preliminary simulations of the scanner and the probe under ideal conditions show a slight improvement in the position reconstruction compared to the data obtained with the scanner, therefore we expect a considerable improvement when using the probe in a total-body PET scanner. Characterisation tests of the probe have been performed with a Na-22 point-like source, obtaining an energy resolution of 9.09% for the 511 keV energy peak and a temporal resolution of 619 ps after time walk correction. The next step of the project is to test the probe measuring in temporal coincidence with the scanner

Red de investigación sobre la docencia de las TIC en los estudios de Filología Española

Este trabajo sintetiza los resultados alcanzados en la “Red de investigación sobre la docencia de las TIC en los estudios de Filología Española”. La comparación y reflexión de las asignaturas de los planes de estudio de Filología Española en las que se explican las TIC para el proceso de enseñanza/aprendizaje de la lengua y la literatura ha permitido solucionar las coincidencias encontradas a través del establecimiento de niveles de profundización o ámbitos de actuación. Además, los cambios realizados responden a varios grados de profundidad: en algunos casos se han matizado ciertos aspectos, en otros se han marcado cambios para evitar coincidencias puntuales y, finalmente, en algún caso concreto se han llevado a cabo remodelaciones internas para resolver solapamientos manifiestos. En definitiva, se ha conseguido una visión global de cómo se abordan las TIC en estos estudios para que el profesorado tenga la seguridad de que está tratando los contenidos, recursos y aplicaciones más adecuados al nivel de especialización de su asignatura y para que el alumnado que las cursa no repita contenidos y avance progresivamente en la adquisición de las habilidades en el uso de las TIC

Spearfishing Regulation Benefits Artisanal Fisheries: The ReGS Indicator and Its Application to a Multiple-Use Mediterranean Marine Protected Area

The development of fishing efficiency coupled with an increase of fishing effort led to the overexploitation of numerous natural marine resources. In addition to this commercial pressure, the impact of recreational activities on fish assemblages remains barely known. Here we examined the impact of spearfishing limitation on resources in a marine protected area (MPA) and the benefit it provides for the local artisanal fishery through the use of a novel indicator. We analysed trends in the fish assemblage composition using artisanal fisheries data collected in the Bonifacio Strait Natural Reserve (BSNR), a Mediterranean MPA where the spearfishing activity has been forbidden over 15% of its area. Fish species were pooled into three response groups according to their target level by spearfishing. We developed the new flexible ReGS indicator reflecting shifts in species assemblages according to the relative abundance of each response group facing external pressure. The catch per unit effort (CPUE) increased by ca. 60% in the BSNR between 2000 and 2007, while the MPA was established in 1999. The gain of CPUE strongly depended on the considered response group: for the highly targeted group, the CPUE doubled while the CPUE of the untargeted group increased by only 15.5%. The ReGS value significantly increased from 0.31 to 0.45 (on a scale between 0 and 1) in the general perimeter of this MPA while it has reached a threshold of 0.43, considered as a reference point, in the area protected from spearfishing since 1982. Our results demonstrated that limiting recreational fishing by appropriate zoning in multiple-use MPAs represents a real benefit for artisanal fisheries. More generally we showed how our new indicator may reveal a wide range of impacts on coastal ecosystems such as global change or habitat degradation