Macrophotography and Microscopy Approaches for Marine Biology, 2013
In this chapter we describe computer-based tomographic methods using magnetic resonance imaging (... more In this chapter we describe computer-based tomographic methods using magnetic resonance imaging (MRI) and X-ray absorption as well as Xray phase-contrast imaging techniques. The latter are based on refraction and near-field diffraction of X-rays and are gaining increased attention due to the increase in sensitivity they offer over conventional, attenuationbased X-ray techniques. The increased sensitivity is of particular interest in marine biology imaging, especially for soft tissue visualization and analysis. The basic principles of the imaging techniques are described, starting with an analysis of the image formation process, followed by a review of several tomography methods, such as MRI or X-ray imaging, and practical guidelines for parameter selection. Finally, two relevant examples of imaging are presented: imaging in marine biology (segmentation and visualization) and small animal (sea horse) imaging. These examples illustrate imaging under different conditions and using different reconstruction options.
Intensive synchrotron X-ray microbeams form an integral part of microbeam radiation therapy (MRT)... more Intensive synchrotron X-ray microbeams form an integral part of microbeam radiation therapy (MRT). MRT is a novel radiation medicine modality being developed for inoperable and otherwise untreatable brain tumours. The extremely high dose rate (∼20 kGy/s), laterally fractionated radiation field and steep dose gradients utilized in this therapy make real-time dosimetry a significant challenge. In order for this treatment to advance
In this work we have characterised the K-edge digital subtraction angiography imaging system at t... more In this work we have characterised the K-edge digital subtraction angiography imaging system at the European Synchrotron Radiation Facility (ESRF, Grenoble, France). With this technique, after the minimally invasive intravenous injection of a contrast agent (iodine), two images are recorded simultaneously using monochromatic beams with energies bracketing the iodine K-edge. The image receptor consists of a two-line 432-pixel germanium detector. The logarithmic subtraction of the image set produced results in an iodine-enhanced image, where vessels are clearly visualised and contrast agent concentration can be precisely quantified. We have studied the imaging system in terms of the modulation transfer function, which was measured at the patient position, the 2-D normalised noise power spectrum, calculated for both raw and processed data, and the frequency-dependent detective quantum efficiency, which was calculated directly for final images. In addition, images of cylindrical phantoms with different concentrations of iodine, were also acquired.
We present images of a mammographic test object obtained using a linear array silicon pixel detec... more We present images of a mammographic test object obtained using a linear array silicon pixel detector capable of single-photon counting. The detector pixel size was 200 x 300 microns2 and images were acquired by scanning the test object between the laminar detector and the x-ray source with a scanning step of 100 microns. A molybdenum anode tube was used with two different filtrations: 2 mm aluminium and 25 microns molybdenum. Conventional film-screen images were also obtained in order to compare spatial and contrast resolution. In our digital images it is possible to recognize low-contrast details having dimensions smaller than or equal to the dimensions of details visible by means of a clinical mammographic unit. The detection of microcalcifications smaller than 150 microns was possible only when using the Mo filtration. However a copper wire of 50 microns diameter was detectable when embedded in a simulated tissue. We discuss in detail the mean glandular doses (MGDs) delivered during the image acquisition. The MGDs necessary to obtain good-quality images are always smaller than at a conventional mammographic unit. Since MGDs depend on the x-ray spectrum, the dose reduction becomes larger when the applied spectrum is harder than in film-screen acquisition (Al filtration and 35 kVp).
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 1998
The SYRMEP (SYnchrotron Radiation for MEdical Physics) collaboration is presently taking data at ... more The SYRMEP (SYnchrotron Radiation for MEdical Physics) collaboration is presently taking data at a beamline at the synchrotron ELETTRA in Trieste to study the performances of a digital silicon pixel imaging system for mammography. Images are obtained with a scanning technique in the energy range 15–30keV. The readout electronics operates in a single photon counting mode with a photon rate of about 106/(mm2s), which is still 4 times lower than the maximum rate reachable with the present beamline configuration. Two different detector layouts have been designed, the first one consisting of a single-layer silicon microstrip detector positioned edge-on with respect to the beam, and the second innovative one represented by a matrix of these detectors stacked to cover the full beam dimension (100×4mm2). We present here the results obtained with a single-layer detector and a double-layer detector (both 5cm wide) with mammographic phantoms and human breast tissue.
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2003
The evaluation of the image quality of the angiography imaging system used at the Medical Beamlin... more The evaluation of the image quality of the angiography imaging system used at the Medical Beamline of European Synchrotron Radiation Facility (ESRF) is presented. A two-line 432-pixel germanium detector is utilized in the human coronary angiography program. The performances have ...
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2003
Diffraction Enhanced Imaging (DEI) can significantly improve the expressiveness of radiology. The... more Diffraction Enhanced Imaging (DEI) can significantly improve the expressiveness of radiology. The contrast mechanism of DEI, in addition to absorption contrast, exploits the differences in X-ray refraction properties, which are sensed by a perfect crystal placed between the ...
Besides attenuation, x-ray refraction occurs in an x-ray beam passing through an object containin... more Besides attenuation, x-ray refraction occurs in an x-ray beam passing through an object containing details of different refractive indices or of non-uniform thicknesses. The emerging x-rays present characteristic angular deflections, which are on the microradian scale. ...
Microbeam radiation therapy (MRT), a novel experimental radiosurgery that largely spares the deve... more Microbeam radiation therapy (MRT), a novel experimental radiosurgery that largely spares the developing CNS and other normal tissues, is tolerated well by developing animals and palliates advanced 9LGS tumors. This report, to our knowledge, is the first demonstration that gene-mediated immunotherapy (GMIMPR) enhances the efficacy of MRT for advanced 9LGS tumors. Seventy-six male Fischer 344 rats were implanted ic with 10(4)9LGS cells on d0. By d14, the cells had generated approximately approximately 40 mm3 ic 9LGS tumours, experimental models for therapy of moderately aggressive human malignant astrocytomas. Each of the 14 untreated (control) rats died from a large (>100 mg) ic tumor before d29 (median, d21). On d14, the remaining 62 rats were given deliberately suboptimal microbeam radiation therapy (MRT) by a single lateral exposure of the tumor-bearing zone of the head to a 10.1 mm-wide, approximately approximately 11 mm-high array of 20-39 microm-wide, nearly parallel beams of synchrotron wiggler-generated radiation (mainly approximately 50-150 keV X-rays) that delivered 625 Gy peak skin doses at approximately approximately 211 microm ctc intervals in approximately approximately 300 ms either without additional treatments (MRT-only, 25 rats), with post-MRT GMIMPR (MRT+GMIMPR, 23 rats: multiple sc injections of irradiated (clonogenically-disabled) GM-CSF gene-transfected 9LGS cells), or with post-MRT IMPR (MRT+IMPR, 14 rats: multiple sc injections of irradiated (clonogenically-disabled) 9LGS cells. The median post-implantation survivals of rats in the MRT-only, MRT+GMIMPR and MRT+IMPR groups were over twice that of controls; further, approximately approximately 20% of rats in MRT-only and MRT+IMPR groups survived >1 yr with no obvious disabilities. Moreover, over 40% of MRT+GMIMPR rats survived >1 yr with no obvious disabilities, a significant (P<0.04) increase over the MRT-only and MRT+IMPR groups. These data suggest that the combination of MRT+GMIMPR might be better than MRT only for unifocal CNS tumors, particularly in infants and young children.
Macrophotography and Microscopy Approaches for Marine Biology, 2013
In this chapter we describe computer-based tomographic methods using magnetic resonance imaging (... more In this chapter we describe computer-based tomographic methods using magnetic resonance imaging (MRI) and X-ray absorption as well as Xray phase-contrast imaging techniques. The latter are based on refraction and near-field diffraction of X-rays and are gaining increased attention due to the increase in sensitivity they offer over conventional, attenuationbased X-ray techniques. The increased sensitivity is of particular interest in marine biology imaging, especially for soft tissue visualization and analysis. The basic principles of the imaging techniques are described, starting with an analysis of the image formation process, followed by a review of several tomography methods, such as MRI or X-ray imaging, and practical guidelines for parameter selection. Finally, two relevant examples of imaging are presented: imaging in marine biology (segmentation and visualization) and small animal (sea horse) imaging. These examples illustrate imaging under different conditions and using different reconstruction options.
Intensive synchrotron X-ray microbeams form an integral part of microbeam radiation therapy (MRT)... more Intensive synchrotron X-ray microbeams form an integral part of microbeam radiation therapy (MRT). MRT is a novel radiation medicine modality being developed for inoperable and otherwise untreatable brain tumours. The extremely high dose rate (∼20 kGy/s), laterally fractionated radiation field and steep dose gradients utilized in this therapy make real-time dosimetry a significant challenge. In order for this treatment to advance
In this work we have characterised the K-edge digital subtraction angiography imaging system at t... more In this work we have characterised the K-edge digital subtraction angiography imaging system at the European Synchrotron Radiation Facility (ESRF, Grenoble, France). With this technique, after the minimally invasive intravenous injection of a contrast agent (iodine), two images are recorded simultaneously using monochromatic beams with energies bracketing the iodine K-edge. The image receptor consists of a two-line 432-pixel germanium detector. The logarithmic subtraction of the image set produced results in an iodine-enhanced image, where vessels are clearly visualised and contrast agent concentration can be precisely quantified. We have studied the imaging system in terms of the modulation transfer function, which was measured at the patient position, the 2-D normalised noise power spectrum, calculated for both raw and processed data, and the frequency-dependent detective quantum efficiency, which was calculated directly for final images. In addition, images of cylindrical phantoms with different concentrations of iodine, were also acquired.
We present images of a mammographic test object obtained using a linear array silicon pixel detec... more We present images of a mammographic test object obtained using a linear array silicon pixel detector capable of single-photon counting. The detector pixel size was 200 x 300 microns2 and images were acquired by scanning the test object between the laminar detector and the x-ray source with a scanning step of 100 microns. A molybdenum anode tube was used with two different filtrations: 2 mm aluminium and 25 microns molybdenum. Conventional film-screen images were also obtained in order to compare spatial and contrast resolution. In our digital images it is possible to recognize low-contrast details having dimensions smaller than or equal to the dimensions of details visible by means of a clinical mammographic unit. The detection of microcalcifications smaller than 150 microns was possible only when using the Mo filtration. However a copper wire of 50 microns diameter was detectable when embedded in a simulated tissue. We discuss in detail the mean glandular doses (MGDs) delivered during the image acquisition. The MGDs necessary to obtain good-quality images are always smaller than at a conventional mammographic unit. Since MGDs depend on the x-ray spectrum, the dose reduction becomes larger when the applied spectrum is harder than in film-screen acquisition (Al filtration and 35 kVp).
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 1998
The SYRMEP (SYnchrotron Radiation for MEdical Physics) collaboration is presently taking data at ... more The SYRMEP (SYnchrotron Radiation for MEdical Physics) collaboration is presently taking data at a beamline at the synchrotron ELETTRA in Trieste to study the performances of a digital silicon pixel imaging system for mammography. Images are obtained with a scanning technique in the energy range 15–30keV. The readout electronics operates in a single photon counting mode with a photon rate of about 106/(mm2s), which is still 4 times lower than the maximum rate reachable with the present beamline configuration. Two different detector layouts have been designed, the first one consisting of a single-layer silicon microstrip detector positioned edge-on with respect to the beam, and the second innovative one represented by a matrix of these detectors stacked to cover the full beam dimension (100×4mm2). We present here the results obtained with a single-layer detector and a double-layer detector (both 5cm wide) with mammographic phantoms and human breast tissue.
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2003
The evaluation of the image quality of the angiography imaging system used at the Medical Beamlin... more The evaluation of the image quality of the angiography imaging system used at the Medical Beamline of European Synchrotron Radiation Facility (ESRF) is presented. A two-line 432-pixel germanium detector is utilized in the human coronary angiography program. The performances have ...
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2003
Diffraction Enhanced Imaging (DEI) can significantly improve the expressiveness of radiology. The... more Diffraction Enhanced Imaging (DEI) can significantly improve the expressiveness of radiology. The contrast mechanism of DEI, in addition to absorption contrast, exploits the differences in X-ray refraction properties, which are sensed by a perfect crystal placed between the ...
Besides attenuation, x-ray refraction occurs in an x-ray beam passing through an object containin... more Besides attenuation, x-ray refraction occurs in an x-ray beam passing through an object containing details of different refractive indices or of non-uniform thicknesses. The emerging x-rays present characteristic angular deflections, which are on the microradian scale. ...
Microbeam radiation therapy (MRT), a novel experimental radiosurgery that largely spares the deve... more Microbeam radiation therapy (MRT), a novel experimental radiosurgery that largely spares the developing CNS and other normal tissues, is tolerated well by developing animals and palliates advanced 9LGS tumors. This report, to our knowledge, is the first demonstration that gene-mediated immunotherapy (GMIMPR) enhances the efficacy of MRT for advanced 9LGS tumors. Seventy-six male Fischer 344 rats were implanted ic with 10(4)9LGS cells on d0. By d14, the cells had generated approximately approximately 40 mm3 ic 9LGS tumours, experimental models for therapy of moderately aggressive human malignant astrocytomas. Each of the 14 untreated (control) rats died from a large (>100 mg) ic tumor before d29 (median, d21). On d14, the remaining 62 rats were given deliberately suboptimal microbeam radiation therapy (MRT) by a single lateral exposure of the tumor-bearing zone of the head to a 10.1 mm-wide, approximately approximately 11 mm-high array of 20-39 microm-wide, nearly parallel beams of synchrotron wiggler-generated radiation (mainly approximately 50-150 keV X-rays) that delivered 625 Gy peak skin doses at approximately approximately 211 microm ctc intervals in approximately approximately 300 ms either without additional treatments (MRT-only, 25 rats), with post-MRT GMIMPR (MRT+GMIMPR, 23 rats: multiple sc injections of irradiated (clonogenically-disabled) GM-CSF gene-transfected 9LGS cells), or with post-MRT IMPR (MRT+IMPR, 14 rats: multiple sc injections of irradiated (clonogenically-disabled) 9LGS cells. The median post-implantation survivals of rats in the MRT-only, MRT+GMIMPR and MRT+IMPR groups were over twice that of controls; further, approximately approximately 20% of rats in MRT-only and MRT+IMPR groups survived >1 yr with no obvious disabilities. Moreover, over 40% of MRT+GMIMPR rats survived >1 yr with no obvious disabilities, a significant (P<0.04) increase over the MRT-only and MRT+IMPR groups. These data suggest that the combination of MRT+GMIMPR might be better than MRT only for unifocal CNS tumors, particularly in infants and young children.
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Papers by Alberto Bravin