Propuesta metodológica para la delimitación de áreas por uso del suelo

Ponencia presentada en el IV Jornada Nacional de Suelos de Ambientes Semiáridos, Córdoba, Argentina, 25 al 26 de septiembre del 2019.Fil: Faraoni, Daniel Alejandro. Universidad Nacional de Córdoba. Facultad de Ciencias Agropecuarias; Argentina.Fil: Ciampagna, Guillemo José. Universidad Nacional de Córdoba. Facultad de Ciencias Agropecuarias; Argentina.Fil: Negro, Gustavo José. Universidad Nacional de Córdoba. Facultad de Ciencias Agropecuarias; Argentina.La información provista por sensores remotos en satélites es importante para estudios relacionados con el uso y ocupación del suelo; siendo la clasificación de las imágenes obtenidas una de las herramientas de la teledetección. El objetivo de este estudio fue elaborar un protocolo de trabajo para delimitar áreas según el uso del suelo definiendo así diferentes clases sobre la cuenca de Lozada, Córdoba. Dado que el proceso de clasificación es un flujo de trabajo de varios pasos, a continuación, se describe la secuencia propuesta. Primero: Reunir las imágenes de la zona y fecha de interés, en este caso se buscó etapas avanzadas de los cultivos (marzo-abril de las campañas 2013-2014 hasta la 2018-2019). Segundo: Componer imágenes multiespectrales. Tercero: Recortar las imágenes (para delimitar el área de estudio). Cuarto: Realizar una clasificación supervisada. Para este estudio las clases fueron Gramíneas, Leguminosas y Monte. Quinto: Transformar la imagen de formato ráster a vector. Sexto: Corregir los vectores (principalmente eliminar los polígonos menores a una hectárea). Séptimo: Elaborar cartografía adecuada para visualizar la distribución espacial de la clasificación realizada. La aplicación de la metodología propuesta permitió determinar las siguientes clases: Agrícola (85,6%), Monte (3,7%), Urbanizado (2,3%), Rutas y Caminos (1,7%). A partir de la clasificación supervisada se determinó que Leguminosas ocupó el 65,3%, y Gramíneas 20.3%. Para las seis campañas analizadas se establecieron cuatro categorías 0:6; 1:6; 1:3; y 1:1, en base a la relación Gramíneas:Leguminosas. Los porcentajes de superficie agrícola obtenidos para cada categoría fueron 0%, 16,7%, 33,3% y 50%, respectivamente.Fil: Faraoni, Daniel Alejandro. Universidad Nacional de Córdoba. Facultad de Ciencias Agropecuarias; Argentina.Fil: Ciampagna, Guillemo José. Universidad Nacional de Córdoba. Facultad de Ciencias Agropecuarias; Argentina.Fil: Negro, Gustavo José. Universidad Nacional de Córdoba. Facultad de Ciencias Agropecuarias; Argentina

Performance evaluation of a new gamma imager for small animal SPECT applications

Proceeding of: 2007 IEEE Nuclear Science Symposium Conference Record (NSS '07), Honolulu, Hawaii, USA, Oct. 27 - Nov. 3, 2007Abstract–In this work we characterized a recently developed gamma imager for small animal SPECT applications. The Hamamatsu C9177 is a mini-gamma camera that integrates the detector and all the electronics, including the acquisition system, in a compact and portable housing. The detector is based on a high resolution parallel hole collimator, a CsI(NaI) crystal array and a PS-PMT (flat panel type). The active field of view is 41.9 x 41.9 mm2 and the assembly is optimized for 60 to 200 keV. The electronics in the housing includes the high voltage divider, an ASIC which converts the 64 anodes into Anger-like signals, ADCs which are fed with these signals and position and energy lookup tables which allow digital information for each detected photon to be obtained directly from the imager. In order to be able to obtain tomographic data and to improve the measurement protocols, we mounted the detector in a custom-built motorized gantry. We evaluated detector uniformity and energy resolution using a flood field image. Planar intrinsic spatial resolution and spatial linearity were assessed by stepping a capillary source across the detector surface and plotting the count profile for each individual crystal of the array. We additionally performed phantom studies to preliminarily characterize the tomographic performance. Energy resolution is 11.6% (mean), sensitivity is 2.54 cps/μCi and planar spatial resolution is 2.4 mm (CFOV 20% energy window) when the source is placed on the detector surface.This work was supported in part by the Spanish Ministerio de Educación y Ciencia under Grant No. TEC2004-07052-C02, Comunidad de Madrid Grant No. GR/SAL/024104, and the CDTEAM project of the CENIT program (Spanish Ministerio de Industria)

A super- resolution feasibility study in small-animal SPECT imaging

Proceeding of: 2008 IEEE Nuclear Science Symposium Conference Record (NSS '08), Dresden, Germany, 19-25 Oct. 2008Lack of spatial resolution is a major drawback in small-animal SPECT imaging, particularly when parallel hole collimators are employed. This work evaluates the feasibility of enhancing the spatial resolution of a small-animal SPECT scanner by applying an approach based on a super-resolution technique combined with dedicated hardware. The detectors are based on PS-PMTs (Hamamatsu, H8500), NaI(TI) crystal arrays and parallel hole collimators. The system enables the mechanical shifting of the gamma-cameras and the object under study during the acquisition in steps smaller than the detector intrinsic sampling pitch. This fact allows using a super-resolution technique without the necessity of blind movement estimators between projections. In the absence of noise the algorithm converged to the original image, and with real noisy data it achieved improvements in resolution between 28%(tomographic) and 42% (planar) in phantom studies.This work is partially funded by the CD-TEAM Project, CENIT Program, Spanish Ministerio de Industria, and with grants from the Ministerio de Educaci6n y Ciencia, projects TEC2007-64731 and TEC2008-06715-C02-01

Assessment of a new CT system for small animals

Proceeding of: 2006 IEEE Nuclear Science Symposium Conference Record, San Diego, CA, Oct. 29 - Nov. 1, 2006We have developed an X-ray cone beam tomograph for in vivo small-animal imaging using a flat panel detector (CMOS technology with a columnar CsI scintillator plate) and a microfocus X-ray source in a geometric configuration with 1.6 magnification and 7.5 cm2 field of view. This work presents an initial characterization of this new system. We measured the detector modulation transfer function (MTF), detector stability, system resolution, the quality of the reconstructed tomographic images and radiated dose. The system resolution was measured following the standard test method ASTM E1696-95. For image quality evaluation, we assessed signal to noise ratio (SNR) and contrast to noise ratio (CNR) with respect to radiated dose. Measurements have been performed on Hounsfield-calibrated images of quantitative phantoms. Effective dose studies have been performed introducing TLD dosimeters in representative organs (ICRU criteria) of euthanized laboratory rats for different imaging protocols. Noise measurements indicate that 50 HU can be achieved at a dose of 10 cGy. Effective dose in standard research methods is below 200 mSv, confirming that the system is appropriate for in vivo imaging. Maximum spatial resolution achieved is better than 50 microns. Experimental results on image quality phantoms as well as on in-vivo studies show that the use of CMOS flat panel is a good choice in terms of quality with respect to radiated dose.This work was supported in part by the Spanish Ministerio de Educación y Ciencia under Grant No. TEC2004-07052-C02, la Comunidad de Madrid Grant No. GR/SAL/024104 CD Team,and the CENIT program of the Spanish Ministerio de Industria

Design and development of a high performance micro-CT system for small-animal imaging

Proceeding of: 2006 IEEE Nuclear Science Symposium Conference Record, San Diego, CA, Oct. 29 - Nov. 1, 2006The goal of this work was the development of a lowcost micro-CT scanner, which could be used as an add-on in our previously developed PET systems for small-animals. The scanner design consists of a single-processor computer controlling a micro-focus X-ray tube and a flat panel detector, assembled in a common rotating gantry. The geometrical configuration was selected to achieve a spatial resolution of about 12 lp/mm with a field of view appropriate for small animals such as mice and rats. The radiated dose is controlled during the acquisition by two different elements: an aluminium filter and a tungsten shutter, attached to the X-ray source. The shutter is controlled by the computer in synchronism with the gantry rotation and the detector image integration. In order to achieve high performance with regards to per-animal screening time and cost, the acquisition protocol is able to take advantage from the highest frame rate of the detector also performing onthe-fly corrections for the detector raw data. These corrections include geometrical misalignments, sensor non-uniformities and defective elements, as well as conversion to attenuation images. An FDK reconstruction algorithm adapted to the specific conebeam geometry has been implemented. Symmetries are exploited to accelerate the algorithm and fast back-projection techniques have been developed for those protocols where high resolution is not a requirement.This work was supported in part by the Spanish Ministerio de Educación y Ciencia under Grant No. TEC2004-07052-C02, la Comunidad de Madrid Grant No. GR/SAL/024104 CD Team, and the CENIT program of the Spanish Ministerio de Industria

Development and performance of the small-animal R-SPECT prototype

[Poster] 4th European Molecular Imaging Meeting, Barcelona, Spain, May 27 - 30, 2009In vivo molecular imaging of small animals has become an essential technique in biomedical research since the introduction of dedicated PeT and SPeCT scanners. however, the capabilities of these typically very expensive machines often exceed the requirements to accomplish common protocols encountered in practice. accordingly, we have developed a simple and compact small-animal SPeCT system, addressed to be used either as an add-on for existing small-animal CT or PeT scanners, or as a stand-alone single photon imagerThis work is supported by Ministerio de Ciencia e innovación (TeC2008-06715-C02-01 and TeC2007-64731/TCM), Ministerio de industria (CdTeaM, Programa CeniT), and the reCaVa-reTiC network.Publicad

rSPECT: a compact gamma camera based SPECT system for small-animal imaging

Proceeding of: 2009 IEEE Nuclear Science Symposium Conference Record (NSS/MIC), Orlando, Florida, 25-31 October 2009We have developed a compact and modular gamma camera system and assessed its performance when used on a small-animal SPECT prototype (rSPECT). Each camera consists of a Hamamatsu H-8500 position sensitive photomultiplier tube coupled to a 30 x 30 NaI (Tl) scintillator array (1.4mm x 1.4mm x 6mm crystal size) and electronics for pre-processing and matching the detector signals to an in-house developed data acquisition system. The camera components are enclosed in a lead-shielded case with a receptacle to insert the collimators (parallel-hole or pinhole with different tungsten apertures). System performance has been assessed for a low energy high resolution parallel-hole collimator (LEHR), and for a 0.75 mm pinhole collimator with 60º aperture angle. In this paper we present details on the system implementation and results of performance measurements, as well as first tomographic images on phantoms and animals. This SPECT was conceived for compactness and cost-effective routine small-animal imaging, and acquisitions of living mice and rats carried out with the system demonstrate its ability to provide useful high-resolution images for in vivo research.This work is partially funded by the CD TEAM project, CENIT Program, Spanish Ministerio de Industria and with grants from the Ministerio de Educación y Ciencia, Projects TEC2007 64731/TCM, TEC2008 06715 C02 01, SAF2009 08076 and the RECAVA RETIC Network

VrPET/CT: development of a rotating multimodality scanner for small-animal imaging

Proceeding of: 2008 IEEE Nuclear Science Symposium Conference Record (NSS '08), Dresden, Germany, 19-25 Oct. 2008This work reports on the development and evaluation of the PET component of a PETtCT system for small-animal in-vivo imaging. The PET and CT subsystems are assembled in a rotary gantry in such a way that the center of rotation for both imaging modalities is mechanically aligned. The PET scanner configuration is based on 2 detector modules, each of which consist of 2 flat-panel type PS-PMTs (Hamamatsu, H8500) and 2 (30 x 30 elements) LYSO arrays. The dimension of the crystal matrix elements are 1.4 x 1.4 mm2 in cross section and 12 mm in depth. The VrPET detector modules are positioned in opposite sides of a 140 mm diameter ring, providing a transaxial field of view of 86.6 mm diameter and an axial field of view of 45.6 mm. The experimental results obtained in the performance tests are transaxial resolution of 1.5 mm FWHM in the CFOV, and the axial resolution of 2.3 mm FWHM. The absolute coincidence sensitivity is 2.22 % for a coincidence window of 6 ns (100-700 keY). The imaging capability of the PET unit is demonstrated on phantom and animal studies.This work is partially funded by the CD-TEAM project, CENIT Program, Spanish Ministerio de Industria and with grants from the Ministerio de Educaci6n y Ciencia, Projects TEC2007-6473I and TEC2008-06715-C02-01Publicad

Assessment of a New High-Performance Small-Animal X-Ray Tomograph

We have developed a new X-ray cone-beam tomograph for in vivo small-animal imaging using a flat panel detector (CMOS technology with a microcolumnar CsI scintillator plate) and a microfocus X-ray source. The geometrical configuration was designed to achieve a spatial resolution of about 12 lpmm with a field of view appropriate for laboratory rodents. In order to achieve high performance with regard to per-animal screening time and cost, the acquisition software takes advantage of the highest frame rate of the detector and performs on-the-fly corrections on the detector raw data. These corrections include geometrical misalignments, sensor non-uniformities, and defective elements. The resulting image is then converted to attenuation values. We measured detector modulation transfer function (MTF), detector stability, system resolution, quality of the reconstructed tomographic images and radiated dose. The system resolution was measured following the standard test method ASTM E 1695 -95. For image quality evaluation, we assessed signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) as a function of the radiated dose. Dose studies for different imaging protocols were performed by introducing TLD dosimeters in representative organs of euthanized laboratory rats. Noise figure, measured as standard deviation, was 50 HU for a dose of 10 cGy. Effective dose with standard research protocols is below 200 mGy, confirming that the system is appropriate for in vivo imaging. Maximum spatial resolution achieved was better than 50 micron. Our experimental results obtained with image quality phantoms as well as with in-vivo studies show that the proposed configuration based on a CMOS flat panel detector and a small micro-focus X-ray tube leads to a compact design that provides good image quality and low radiated dose, and it could be used as an add-on for existing PET or SPECT scannersIEEE Nuclear and Plasma Sciences SocietyPublicad

A spect scanner for rodent imaging based on small-area gamma cameras

We developed a cost-effective SPECT scanner prototype (rSPECT) for in vivo imaging of rodents based on small-area gamma cameras. Each detector consists of a position-sensitive photomultiplier tube (PS-PMT) coupled to a 30 30 NaI(Tl) scintillator array and electronics attached to the PS-PMT sockets for adapting the detector signals to an in-house developed data acquisition system. The detector components are enclosed in a leadshielded case with a receptacle to insert the collimators. System performance was assessed using for a high-resolution parallel- hole collimator, and for a 0.75-mm pinhole collimator with a 60 aperture angle and a 42-mm collimator length. The energy resolution is about 10.7% of the photopeak energy. The overall system sensitivity is about and planar spatial resolution ranges from 2.4 mm at 1 cm source-to-collimator distance to 4.1 mm at 4.5 cm with parallel-hole collimators. With pinhole collimators planar spatial resolution ranges from 1.2 mm at 1 cm source-to-collimator distance to 2.4 mm at 4.5 cm; sensitivity at these distances ranges from 2.8 to . Tomographic hot-rod phantom images are presented together with images of bone, myocardium and brain of living rodents to demonstrate the feasibility of preclinical small-animal studies with the rSPECT.This work was supported in part by the CD-TEAM project, CENIT program, Spanish Ministerio de Industria and with grants from the Ministerio de Educación y Ciencia, Projects TEC2007-64731/TCM, TEC2008-06715-C02-01, SAF2009-08076, program ARTEMIS S2009/DPI-1802, Comunidad de Madrid, and the RECAVA-RETIC NetworkPublicad