Diverse and Active Roles for Adipocytes During Mammary Gland Growth and Function

The mammary gland is unique in its requirement to develop in close association with a depot of adipose tissue that is commonly referred to as the mammary fat pad. As discussed throughout this issue, the mammary fat pad represents a complex stromal microenvironment that includes a variety of cell types. In this article we focus on adipocytes as local regulators of epithelial cell growth and their function during lactation. Several important considerations arise from such a discussion. There is a clear and close interrelationship between different stromal tissue types within the mammary fat pad and its adipocytes. Furthermore, these relationships are both stage- and species-dependent, although many questions remain unanswered regarding their roles in these different states. Several lines of evidence also suggest that adipocytes within the mammary fat pad may function differently from those in other fat depots. Finally, past and future technologies present a variety of opportunities to model these complexities in order to more precisely delineate the many potential functions of adipocytes within the mammary glands. A thorough understanding of the role for this cell type in the mammary glands could present numerous opportunities to modify both breast cancer risk and lactation performance

DESIGN OF A SCATTERING POLARIMETER FOR HARD X-RAY ASTRONOMY

The design of a new hard X-ray Compton scattering polarimeter based on scintillating fibres technology is presented and studied in detail by means of Monte Carlo calculations. Several different configurations and materials have been tested in order to optimise the sensitivity in the medium/high energy X-ray band. A high sensitivity over the energy band 20-200 keV is obtained for a two material configuration. The advantages deriving from employing a new scintillating material, the YAP (YAlO3), are also discussed

Flat panel PMT for photon emission imaging

Over the last 15 years Hamamatsu has been developed two generations of Position Sensitive Photomultipliers (PSPMTs). The first and the second generation were based on mesh dynode and metal channel dynode respectively. In this paper, we present the first results obtained from the last generation: Hamamatsu H8500 Flat Panel PSPMT. The active area is increased to 2 in. with minimum peripheral dead zone and thickness down to 12.5 mm. Measurements were addressed to nuclear medicine for single photon imaging. To this aim, we have taken into account two different electronic readout: resistive chain and multi-anode readout (64 channels). To evaluate the imaging performance, the Flat Panel PSPMT was coupled to CsI(Tl) and NaI(Tl) scintillation arrays with pixel size of 3 and 2 mm, respectively. Images of CsI(Tl) array, obtained by multi-anode readout, showed an improvement of spatial resolution, from 1.2 to 0.8 mm, and of position linearity response. On the contrary for NaI(Tl) array, no relevant image differences between two system readout were obtained. (C) 2003 Elsevier Science B.V. All rights reserved

Preliminary study of different readout strategies for a positron emission mammograph head

We are developing a positron emission mammograph imaging system that consists of 2 planar heads (10 x 10 cm 2), each composed of 4 matrices (5 x 5 cm(2)) of scintillating crystals coupled to the same number of multi-anode PMT (Hamamatsu H8500). We are developing a readout scheme which handles the 4 x 64 output signals of each head. We are primarily interested in charge multiplexed readout schemes. The measurements presented in this paper highlight the limits of a multiplexed readout using a discretized positioning circuit (DPC) by comparison with results using either another multiplexed scheme based on symmetric charge division (SCD) or a multi-anode readout. The measurements have been performed with the H8500 PMT coupled to pixelated NaI(Tl) and YAP crystals. (c) 2006 Elsevier B.V. All rights reserved

Principal component analysis of scintimammographic images

none9The recent development of new gamma imagers based on scintillation array with high spatial resolution, has strongly improved the possibility of detecting sub-centimeter cancer in Scintimammography. However, Compton scattering contamination remains the main drawback since it limits the sensitivity of tumor detection. Principal component image analysis (PCA), recently introduced in scintimammographic imaging, is a data reduction technique able to represent the radiation emitted from chest, breast healthy and damaged tissues as separated images. From these images a Scintimammography can be obtained where the Compton contamination is "removed". In the present paper we compared the PCA reconstructed images with the conventional scintimammographic images resulting from the photopeak (Ph) energy window. Data coming from a clinical trial were used. For both kinds of images the tumor presence was quantified by evaluating the t-student statistics for independent sample as a measure of the signal-to-noise ratio (SNR). Since the absence of Compton scattering, the PCA reconstructed images shows a better noise suppression and allows a more reliable diagnostics in comparison with the images obtained by the photopeak energy window, reducing the trend in producing false positive.noneBonifazzi C; Cinti MN; De Vincentis G; Finos L; Muzzioli V; Betti M; Lanconelli N; Tartari A; Pani RBonifazzi C; Cinti MN; De Vincentis G; Finos L; Muzzioli V; Betti M; Lanconelli N; Tartari A; Pani

Principal component analysis of scintimammographic images

The recent development of new gamma imagers based on scintillation array with high spatial resolution, has strongly improved the possibility of detecting sub-centimeter cancer in Scintimammography. However, Compton scattering contamination remains the main drawback since it limits the sensitivity of tumor detection. Principal component image analysis (PCA), recently introduced in scintimammographic imaging, is a data reduction technique able to represent the radiation emitted from chest, breast healthy and damaged tissues as separated images. From these images a Scintimammography can be obtained where the Compton contamination is "removed". In the present paper we compared the PCA reconstructed images with the conventional scintimammographic images resulting from the photopeak (Ph) energy window. Data coming from a clinical trial were used. For both kinds of images the tumor presence was quantified by evaluating the t-student statistics for independent sample as a measure of the signal-to-noise ratio (SNR). Since the absence of Compton scattering, the PCA reconstructed images shows a better noise suppression and allows a more reliable diagnostics in comparison with the images obtained by the photopeak energy window, reducing the trend in producing false positive

Photodetector and scintillation crystals requirements for gamma-ray imaging RID F-8402-2011

The diffusion of the PET and SPET techniques in different applications, like investigation on small organs and tissues or animal imaging, has induced in the past years the researchers to develop modular scintillation cameras to have compactness and versatility in order to obtain dimensions and configurations suitable to the particular application. To this purpose different pbotodetectors have been studied, as an alternative to the photomultiplier tubes (PMT) based on semiconductor technology. At the same time new scintillating crystals have been tested to match the requirements like high light yield or fast decay time, needed for SPET and PET application, respectively. In this paper we have investigated the photodetector and scintillation crystals requirements to optimize a gamma-ray imager based on scintillation crystals. To this aim we show results about the principal parameters characterizing a gamma-ray imaging, like energy and spatial resolution. The performances of a continuous LaBr3:Ce crystal (49 x 49 x 4 mm(3) + 3 mm glass window) are compared to the ones from a pixellated and continuous NaI:Tl crystal, coupled to multi-anode photomultiplier tube (Hamamatsu H8500 MA-PMT). Furthermore the results are supported with Monte Carlo simulations. With the lanthanum detector, we obtain 1.1 mm of intrinsic spatial resolution, comparable with that predicted by the MC simulations. We test also the new ultra bialkali PMT Hamamatsu R7600-200 with a QE = 42%, obtaining an improvement in terms of energy resolution of about 25%, respect to a standard PMT, with a LaBr3:Ce cylinder (1/2 ''phi x 1/2 '' thickness)

SPEMT imaging with a dedicated VAoR dual-head camera: preliminary results

We have developed a SPEMT (Single Photon Emission MammoTomography) scanner that is made up of two cameras rotating around the pendulous breast of the prone patient, in Vertical Axis of Rotation (VAoR) geometry. Monte Carlo simulations indicate that the device should be able to detect tumours of 8 mm diameter with a tumour/background uptake ratio of 5:1. The scanner field of view is 41.6 mm height and 147 mm in diameter. Each head is composed of one pixilated NaI(Tl) crystal matrix coupled to three Hamamatsu H8500 64-anodes PMT's read out via resistive networks. A dedicated software has been developed to combine data from different PMT's, thus recovering the dead areas between adjacent tubes. A single head has been fully characterized in stationary configuration both in active and dead areas using a point-like source in order to verify the effectiveness of the readout method in recovering the dead regions. The scanner has been installed at the Nuclear Medicine Division of the University of Pisa for its validation using breast phantoms. The very first tomographic images of a breast phantom show a good agreement with Monte Carlo simulation results