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Evaluation of the radioisotopic purity of technetium-99m (

The aim of the SCINTIRAD experiment is to determine the radio-response of 188Rhenium (Re) in in vitro cells and the biodistribution in different organs of in vivo mice, and subsequently to assess the therapeutic effect on liver tumours induced in mice. Both the γ- and β- emissions of 188Re have been exploited in the experiment. The in vivo biodistribution in mice was studied also with a γ-camera using different parallel hole collimators. In the 188Re spectrum, while the 155 keV γ-peak is useful for imaging, the photons emitted at larger energies and the β-particles act as noise in the image reconstruction. The γ-cameras previously used to image biodistributions obtained with 99Tc are, therefore, not optimized for use with 188Re. A new setup of the γ-camera has been studied for 188Re: 66×66 YAP:Ce crystals (0.6×0.6×10 mm3, 5 μm optical insulation) guarantee a FOV of 40×40 mm2, a Hamamatsu R2486 PSPMT, 3 in. diameter, converts their light into an electrical signal and allows reconstructing the spatial coordinates of the light spot; incoming photon directions are selected through a lead collimator with 1.5 mm diameter hexagonal holes, 0.18 mm septa, 40 mm thickness. Using this setup, results have been obtained both with 99Tc filled and 188Re filled capillaries and wells. The energy spectrum of the collected photons and the spatial resolutions obtainable with the 188Re source will be presented.

In our previous studies we have considered a possible use of a manipulator for biomedical applications guided by the so-called tilting-collimator (TC) scintillation gamma-ray camera. The imaged gamma-ray emitting object is localized exploiting our patented method to determine the camera-to-object distance using a TC camera (patent No RM 2006 A 000216, UIBM Roma). Thus the three coordinates of the object are obtained without moving either the camera or the object.

In our previous studies we have presented a method to measure the detector-to-object distance using a tiltedcollimator (TC) technique. It exploits the shift of the imaged object in the image plane, obtained for tilted positions of a parallel-hole lead collimator. In this work we present the design and first test results of an instrument, which combines the localization of a small-size gamma-ray source with computer-guided precise object manipulation.

In PET Laboratory at the National Laboratories of Legnaro, INFN, we are exploiting a recently developed gamma-ray imaging camera using tilted-collimator (TC) technique. The parallel-hole lead collimator of the camera can be tilted at small angles around an axis parallel to the scintillator plane, thus enabling to determine the distance of imaged objects. However, in order to allow sizeable tilt angles, the collimator-to-scintillator distance has been increased to 8mm. Moreover, when the collimator is tilted at a certain angle the distance between the collimator and the scintillator varies throughout the whole field of view (FOV). These conditions may affect the spatial resolution of the imaging camera. It is important to know how much the collimator-to-scintillator distance and the tilt angle influence the spatial characteristics of the TC camera throughout the whole FOV. In this work the results of the spatial resolution measurements for the TC Yttrium Aluminum Perovskite (YAP) scintillation camera are presented.

In our previous publication we have shown some preliminary results and images obtained using a multiple- wavelength NIR scanning device designed in the Laboratory for Radiopharmaceuticals and Molecular Imaging (LRIM) at the National Laboratories of Legnaro, INFN [1]. The device described there has been designed for simple straight-line scanning of the NIR light transmitted through the scanned object. In this article we present the test results from our conceptually new NIR scanning device realized for small- object and tissue imaging in XY plane.

In our previous publication we have shown some preliminary results and images obtained using a multiple- wavelength NIR scanning device designed in the Laboratory for Radiopharmaceuticals and Molecular Imaging (LRIM) at the National Laboratories of Legnaro, INFN. The device described there has been designed for simple straight-line scanning of the NIR light transmitted through the scanned object. In this article we present the test results from our conceptually new NIR scanning device realized for small- object and tissue imaging in XY plane.

The studies of X-ray attenuation of biological tissues are connected to the possibility of visualizing pathological tissues using new X-ray imaging techniques such as Multi-Energy subtraction X-ray Imaging. In fact the ability to distinguish pathological tissues is strictly related to an accurate knowledge of the X-ray absorption coefficients. A study of the attenuation properties of tissues was started at the University of Bologna in a facility based on a Bragg monochromator. The target of the Bragg monochromator is a LiF crystal able to produce monochromatic beams in a range of energies from 10 keV to 60 keV and with an energy resolution less than 2.0 keV. The absorption data are acquired by a CdTe detector. The energy resolution deterioration caused by the tailing effect at high energies is studied by a comparison with an HPGe detector. We implemented different algorithms for extracting chemical-physical information from X-ray absorption measurements, such as effective atomic number and electron density. The aim of this work is to present an instrumentation dedicated to the measure of the absorption coefficient of materials, in particular biological samples. An important feature of this apparatus is the possibility of selecting the energy of interest with high precision and repeatability. In addition, a study of the energy resolution of CdTe detector is reported, with a comparison with the energy resolution obtained with an HPGe detector for all the analyzed energy ranges. This study also analyzes the error propagation on the absorption curves, and evaluates the error introduced by the intrinsic characteristic of the detector used.

In our previous publications we have already discussed a possible use of a computer-guided manipulator for biomedical applications based on our patented method to determining the camera-to-object distance using the so-called tilting collima- tor (TC) technique. Tests about the accuracy of the object localization and the TC camera spatial resolution have already been conducted. A manipulator for simple mechani- cal operations has already been constructed in the Laboratory for Radiopharmaceuticals and Biomolecular Imaging (LRBI) of the LNL. It is coupled to a TC scintillation camera and it has been designed as a three-segmented arm consisting of three mutually perpendicular linear actuators. The system thus ensures three degrees of freedom motion of the manipulator pointer in a volume of 10x10x10cm 3 in the imaged object ? eld (under the camera). In this article we present the methods for guidance and motion control of the manipulator coupled with the TC scintillation camera.

We plan to combine the tilted-collimator (TC) technique enabling a precise three-dimensional determination of the object position using a high-resolution gamma-ray camera with other imaging technique such as near-infrared (NIR) scanning. The advantage of such a combination would facilitate the application of multimodality imaging to small-sized biological objects. In this aspect a combination of NIR scanning and gamma-ray imaging using a TC-YAP camera could be a useful approach for in-vivo studies of the biodistribution of radiopharmaceuticals, for tumor localization in small animals, etc. A multiple-wavelength NIR scanning device has already been accomplished in the Laboratory for Radiopharmaceuticals and Molecular Imaging (LRIM, the former PET Laboratory) at the National Laboratories of Legnaro, INFN. It has been designed for near-object scanning of the NIR light transmitted through the scanned object that is emitted by a set of ? ve light emitting diodes (LED) with different wavelengths. The process of scanning is realized by a consecutive positioning of an array of NIR detectors (sliding very close to the scanned object) in steps and reading the detector signals at the corresponding positions. Thus, after scanning a set of ? ve images is obtained. The latter allows conducting a multivariate image analysis (MIA) in order to observe small differences in the optical properties of the objects analyzed. In this article we present some preliminary results from the test measurements conducted with this scanner.

Gamma, β + , β - and α emissions of radionuclides can be successfully spoiled in the preparation of radiopharmaceuticals as a useful tool in radiodiagnosis (imaging) and radiotherapy against cancer. For nuclear imaging, 99m Tc has become the “universal” isotope because of its physical characteristics in the field of scintigraphy (6 hours half-life, 140 keV γ emission) [1]. Among the radionuclides the β - emitters are particularly promising in radiotherapy for the capability of their 0.3-2.3 MeV electrons to penetrate tissues in a range of 0.5-12 mm avoiding problems related to cellular internalization of radiopharmaceuticals. 188 Re (16.9 hours half life), a β - and γ emitter similar to the congener 99m Tc, is a promising candidate in nuclear medicine. In fact, while the β - emission (85%, E max = 2.12 MeV) is relevant for therapeutic purposes, the γ-rays (15%, 155 keV) can be detected to evaluate the biodistribution of the radiunuclide. Because of its multiple decay modes, 188 Re might be used for a real-time monitoring of regional drug distribution during radiation therapy. Furthermore 188 Re is available as perrhenate from a 188 W/ 188 Re generator. To date, few data are available in the literature on the sensitivity of different tumour cells to such radionuclide. In this context, the aim of the experiment SCINTIRAD supported by the National Institute for Nuclear Physics (INFN, Italy) is to determine the radio-response of tumour cell lines treated “in vitro” with 188 Re, the biodistribution in different organs of “in vivo” mice and subsequently the therapeutic effect on tumours induced in mice. Furthermore, dedicated devices as an optimized YAP camera for the 188 Re photon spectrum and appropriate software have been developed and improved for imaging of small animals. In particular, we present preliminary results on the genotoxic effect of 188 Re-perrhenate on a panel of human tumour cell lines (U87, H460, MCF-7, LNCaP) in terms of inhibition of cell viability, micronuclei induction and apoptosis.