Paola Maria Frallicciardi - Academia.edu (original) (raw)

Papers by Paola Maria Frallicciardi

L’Azienda USL 6 di Livorno è dotata – unica tra tutte le USL del Servizio Sanitario Nazionale – d... more L’Azienda USL 6 di Livorno è dotata – unica tra tutte le USL del Servizio Sanitario Nazionale – di un Laboratorio Accreditato di Taratura, a cui è stata assegnata la sigla di LAT N° 222 e sede fisica presso l’Unità Operativa di Fisica Sanitaria dell’Azienda livornese. I lavori per il LAT N° 222 sono ufficialmente partiti il 21 ottobre 2008 grazie al Decreto N° 4972 col quale la Regione Toscana approvava il progetto biennale denominato “Centro Regionale di Taratura per le radiazioni ionizzanti”. Nei successivi anni 2009, 2010 e 2011, grazie ai fondi assegnati, è stato possibile attrezzare il Laboratorio con la strumentazione opportuna e, in un secondo momento, approntare una serie di procedure sia tecniche che gestionali che rendessero possibile all’Ente preposto (ACCREDIA) di deliberarne accreditamento, avvenuto nel luglio 2011. Questa tesi descrive il lavoro svolto, a partire dal maggio 2010, per portare all’accreditamento il LAT N° 222 e per le successive implementazioni relative ...

Journal of Nuclear Medicine, 2014

A novel radio guided surgery (RGS) technique for cerebral tumors using β − radiation is being dev... more A novel radio guided surgery (RGS) technique for cerebral tumors using β − radiation is being developed. Checking the availability of a radio-tracer that can deliver a β − emitter to the tumor is a fundamental step in the deployment of such technique. This paper reports a study of the uptake of 90 Y-labeled [1,4,7,10tetraazacyclododecane-N,N ,N ,N-tetraacetic acid0-D-Phe1,Tyr3]octreotide (DOT-ATOC) in the meningioma and the high grade glioma (HGG) and a feasibility study of the RGS technique in these cases. Such estimates are performed assuming the use of a β − probe with a sensitive area of 2.55 mm radius, that is under development, to detect 0.1ml residuals. Methods: the uptake and the background from healthy tissues were estimated on 68 Ga-DOTATOC PET scans of 11 meningioma and 12 HGG patients. A dedicated statistical analysis of the DICOM images was developed and validated. The feasibility study was performed by means of a full simulation of the emission and detection of the radiation, accounting for the measured uptake and background rate. Results: all meningioma patients but one with an atypical extracranial tumor showed a very high uptake of DOTATOC. In terms of feasibility of the RGS technique, we estimated that by administering 3 MBq/kg of radio-tracer, the time needed to detect a 0.1 ml remnant at 95% C.L. is smaller than 1 s. Actually, to achieve a detection time of 1 s the required activities to administer are as low as 0.2-0.5 MBq/kg in a large fraction of the patients. In case of HGGs, the uptake is lower, but the tumor-to-non-tumor ratio is higher than four, which implies that it can still be effective for RGS. It was estimated that by administering 3 MBq of radio-tracer, the time needed to detect a 0.1 ml remnant at 95% C.L. is smaller than 6 s with the exception of the only oligodendrioma in the sample. Conclusion: The uptake of 90 Y-DOTATOC in meningioma is high in all studied patients. As far as HGG is concerned, albeit the uptake is significantly worse, it is still acceptable for RGS, in particular if further R&D is made to improve the performances of the β − probe.

arXiv: Medical Physics, 2016

Charged Particle Therapy is a technique for cancer treatment that exploits hadron beams, mostly p... more Charged Particle Therapy is a technique for cancer treatment that exploits hadron beams, mostly protons and carbons. A critical issue is the monitoring of the dose released by the beam to the tumor and to the surrounding tissues. We present the design of a new tracking device for monitoring on-line the dose in ion therapy through the detection of secondary charged particles produced by the beam interactions in the patient tissues. In fact, the charged particle emission shape can be correlated with the spatial dose release and the Bragg peak position. The detector uses the information provided by 12 layers of scintillating fibers followed by a plastic scintillator and a small calorimeter made of a pixelated Lutetium Fine Silicate crystal. Simulations have been performed to evaluate the achievable spatial resolution and a possible application of the device for the monitoring of the dose profile in a real treatment is presented.

Physica Medica

The aim of this work was to assess the performance of a prototype compact gamma camera (MediPROBE... more The aim of this work was to assess the performance of a prototype compact gamma camera (MediPROBE) based on a CdTe semiconductor hybrid pixel detector, for coded aperture imaging. This probe can be adopted for various tasks in nuclear medicine such as preoperative sentinel lymph node localization, breast imaging with 99m Tc radiotracers and thyroid imaging, and in general in radioguided surgery tasks. The hybrid detector is an assembly of a 1-mm thick CdTe semiconductor detector bump-bonded to a photon-counting CMOS readout circuit of the Medipix2 series or energy-sensitive Timepix detector. MediPROBE was equipped with a set of two coded aperture masks with 0.07-mm or 0.08-mm diameter holes. We performed laboratory measurements of field of view, system spatial resolution, and signal-difference-to-noise ratio, by using gamma-emitting radioactive sources (109 Cd, 125 I, 241 Am, 99m Tc). The system spatial resolution in the lateral direction was 0.56 mm FWHM (coded aperture mask with holes of 0.08 mm and a 60 keV source) at a source-collimator distance of 50 mm and a field of view of 40 mm by side. Correspondingly, the longitudinal resolution in 3D source localization tasks was about 3 mm. MediPROBE showed a significant improvement in terms of spatial resolution when equipped with the high-resolution coded apertures, with respect to the performance previously reported with 1-2 mm pinhole apertures as well as with respect to adopting a 0.35 mm pinhole aperture.

IFMBE Proceedings, 2009

In the framework of a research project for breast Computed Tomography (CT), we studied two differ... more In the framework of a research project for breast Computed Tomography (CT), we studied two different flatfield correction methods for a single photon counting (SPC) semiconductor pixel detector for X-ray CT. The first method is the usual flat field irradiation procedure with a uniform exposure of the detector in air, while the second method uses flat field images obtained by interposing attenuating sheets of material (e.g. Al, PMMA) between the X-ray tube and the detector, in order to account for the beam hardening effect that occurs when imaging a sample in CT. In fact, this effect causes a different detector response than with free-in-air flood irradiations. The experimental setup includes a Medipix2 SPC silicon pixel detector (matrix of 256×256 square pixels of 55 μm pitch) and a micro-focus X-ray tube with a molybdenum anode and a focal spot size of 35 μm. The single photon counting operation of Medipix2 avoids integration of dark current and enables energy discrimination in each pixel, allowing noise rejection and providing high signal to noise ratio. With 13- bit/pixel and a count rate exceeding 105 cps/pixel, the detector permits high flux exposures. We present here two sets of tomographic images of PMMA (1.19 g/cm3) phantoms containing water or high density polyethylene (0.95 g/cm3) as contrast materials. For each set of projections we performed the two types of correction before the tomographic reconstruction. Images are compared in terms of contrast-to-noise ratio.

by Luca Piersanti, F. Collamati, A. Pepe, F. Bellini, Valerio Bocci, Marta Cremonesi, S. Morganti, M. Senzacqua, Davide Pinci, Ilaria Mattei, Paola Maria Frallicciardi, and Alessio Sarti

Journal of Nuclear Medicine, 2014

A novel radioguided surgery (RGS) technique for cerebral tumors using β − radiation is being deve... more A novel radioguided surgery (RGS) technique for cerebral tumors using β − radiation is being developed. Checking for a radiotracer that can deliver a β − emitter to the tumor is a fundamental step in the deployment of such a technique. This paper reports a study of the uptake of 90 Y-DOTATOC in meningiomas and high-grade gliomas (HGGs) and a feasibility study of the RGS technique in these types of tumor. Estimates were performed assuming the use of a β − probe under development with a sensitive area 2.55 mm in radius to detect 0.1-mL residuals. Methods: Uptake and background from healthy tissues were estimated on 68 Ga-DOTATOC PET scans of 11 meningioma patients and 12 HGG patients. A dedicated statistical analysis of the DICOM images was developed and validated. The feasibility study was performed using full simulation of emission and detection of the radiation, accounting for the measured uptake and background rate. Results: All meningioma patients but one with an atypical extracranial tumor showed high uptake of DOTATOC. In terms of feasibility of the RGS technique, we estimated that by administering a 3 MBq/kg activity of radiotracer, the time needed to detect a 0.1-mL remnant with 5% false-negative and 1% falsepositive rates is less than 1 s. Actually, to achieve a detection time of 1 s the required activities to administer were as low as 0.2-0.5 MBq/kg in many patients. In HGGs, the uptake was lower than in meningiomas, but the tumor-to-nontumor ratio was higher than 4, which implies that the tracer can still be effective for RGS. It was estimated that by administering 3 mBq/kg of radiotracer, the time needed to detect a 0.1-mL remnant is less than 6 s, with the exception of the only oligodendroma in the sample. Conclusion: Uptake of 90 Y-DOTATOC in meningiomas was high in all studied patients. Uptake in HGGs was significantly worse than in meningiomas but was still acceptable for RGS, particularly if further research and development are done to improve the performance of the β − probe.

In this work we present the study of applicability of a desktop size radiographic/tomographic X-r... more In this work we present the study of applicability of a desktop size radiographic/tomographic X-ray system for real-time microscopy and micro-tomography in the fields of biology, entomology, botanic and medical imaging. The apparatus is made up of the single photon counting pixel silicon detector, Medipix2 (matrix of 256×256 square pixels of 55 μm pitch) and a microfocus X-ray tube with a minimum spot size of 5 μm and a tungsten anode. The system has been used for observations of time-dependent processes inside living and still biological and organic samples. Excellent contrast and spatial resolution (micrometer scale) were obtained as a combination of a) low photon energy (40 kVp X-ray tube voltage), b) single photon counting operation, witch avoids integration of dark current c) energy discrimination in each pixel, allowing noise rejection and providing high SNR, d) high effective dynamic range for long exposures, which allows for high signal with high SNR, e) implementation of an original procedure for the energy response calibration of each pixel of the detector matrix, f) high speed read-out hardware and software, which opens the possibility to perform real-time studies of biological processes permitting, e.g., observation of morphological changes, mutations or metamorphosis of living animals and plants. Static and dynamic images of a parasite life cycle from the larva stage to pupa stage are presented here, as well as an in vivo computed tomography of the parasite living inside its host.

Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment, 2009

An X-ray micro-radiographic system based on the Medipix2 semiconductor pixel detector for dynamic... more An X-ray micro-radiographic system based on the Medipix2 semiconductor pixel detector for dynamic high spatial resolution and for high contrast imaging has been developed. Our system is based on a micro-focus and nano-focus X-ray tube and the hybrid single-photon counting silicon pixel detector Medipix2 (matrix 256×256 sq. pixels of 55 μm pitch). This compact table-top system stands promising as a new tool in the field of small animal imaging as well as in the in-vivo observation of dynamic processes inside living organisms. The main advantages of these Medipix2 pixel detectors include: high sensitivity to low-energy X-ray photons; position sensitive and noiseless single-photon detection with preselected photon energies; single-quantum counting in each pixel performed by digital counter (therefore there is no dark current); digital integration (providing unlimited dynamic range and absolute linearity in device response to number of photons, high sensitivity and high contrast); real-time digital information, high-speed digital communication and data transfer. We improve the picture quality with the help of statistical data analysis and extended the calibration of individual pixels response. 2D and 3D radiographic images of samples demonstrate the potential and applicability of our system for precise in-vivo X-ray high-resolution dynamic diagnostic and biological studies. Obtained results are shown on small animal and organic samples.

Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment, 2009

This work presents a direct comparison of two pixel detectors: a charge-integrating flat panel im... more This work presents a direct comparison of two pixel detectors: a charge-integrating flat panel imager coupled to a CsI:Tl scintillator and a hybrid silicon detector of Medipix2 type, working in a single-photon counting mode. The comparison concerns image quality in terms of system-spatial resolution, signal-to-noise ratio and contrast in imaging of small biological objects. It will be shown that, at photon energies below 40 keV and for low attenuating biological objects, single-photon counting detectors are more appropriate for small-animal imaging than flat panel devices right due to better spatial resolution, signal-to-noise ratio and contrast.

Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment, 2007

We describe MediSPECT, a new scanner developed at University and INFN Napoli, for SPECT studies o... more We describe MediSPECT, a new scanner developed at University and INFN Napoli, for SPECT studies on small animals with a small field of view (FOV) and high spatial resolution. The CdTe pixel detector (a 256×256 matrix of 55 μm square pixels) operating in single photon counting for detection of gamma-rays with low and medium energy (e.g. 125I, 27–35 keV, 99mTc, 140 keV), is bump bonded to the Medipix2 readout chip. The FOV of the MediSPECT scanner with a coded aperture mask collimator ranges from 6.3 mm (system spatial resolution 110 μm at 27–35 keV) to 24.3 mm. With a 0.30 mm pinhole the FOV ranges from 2.4 to 29 mm (where the system spatial resolution is 1.0 mm at 27–35 keV and 2.0 mm at 140 keV). MediSPECT will be used for in vivo imaging of small organs or tissue structures in mouse, e.g., brain, thyroid, heart or tumor.

Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment, 2007

We report on the tests of a prototype (MediSPECT) system developed at University & INFN Napoli, f... more We report on the tests of a prototype (MediSPECT) system developed at University & INFN Napoli, for Single Photon Emission Computed Tomography (SPECT) imaging on small animals with a small Field of View (FoV) and high spatial resolution. MediSPECT is a SPECT imaging system based on a 1-mm-thick CdTe pixel detector, bump-bonded to the Medipix2 CMOS readout circuit operating in single-photon counting. The CdTe detector has 256×256 square array of pixels arranged with a 55 μm pitch, for a sensitive area of 14×14 mm2. In its present version, this system implements a single detector head, mounted on a rotating gantry. For preliminary testing and calibration of the acquisition equipment and image reconstruction algorithms, 90 projections of a γ-ray point source (109Cd) through a single pinhole (diameter 0.4 mm; radius of rotation about 2.5 cm; focal length about 4.5 cm) were acquired for 20 min each in a step-and-shoot mode. Capillaries, 800 μm in diameter, were arranged in a Y-shape to form a more complex phantom (125I, 1 mm pinhole diameter, 45 projections, each acquired for 25 min). Images were reconstructed with a custom algorithm implementing standard OS-EM with center of rotation correction and spatial resolution of 0.2 mm over a FoV of 2 mm was obtained.

L’Azienda USL 6 di Livorno è dotata – unica tra tutte le USL del Servizio Sanitario Nazionale – d... more L’Azienda USL 6 di Livorno è dotata – unica tra tutte le USL del Servizio Sanitario Nazionale – di un Laboratorio Accreditato di Taratura, a cui è stata assegnata la sigla di LAT N° 222 e sede fisica presso l’Unità Operativa di Fisica Sanitaria dell’Azienda livornese. I lavori per il LAT N° 222 sono ufficialmente partiti il 21 ottobre 2008 grazie al Decreto N° 4972 col quale la Regione Toscana approvava il progetto biennale denominato “Centro Regionale di Taratura per le radiazioni ionizzanti”. Nei successivi anni 2009, 2010 e 2011, grazie ai fondi assegnati, è stato possibile attrezzare il Laboratorio con la strumentazione opportuna e, in un secondo momento, approntare una serie di procedure sia tecniche che gestionali che rendessero possibile all’Ente preposto (ACCREDIA) di deliberarne accreditamento, avvenuto nel luglio 2011. Questa tesi descrive il lavoro svolto, a partire dal maggio 2010, per portare all’accreditamento il LAT N° 222 e per le successive implementazioni relative ...

Journal of Nuclear Medicine, 2014

A novel radio guided surgery (RGS) technique for cerebral tumors using β − radiation is being dev... more A novel radio guided surgery (RGS) technique for cerebral tumors using β − radiation is being developed. Checking the availability of a radio-tracer that can deliver a β − emitter to the tumor is a fundamental step in the deployment of such technique. This paper reports a study of the uptake of 90 Y-labeled [1,4,7,10tetraazacyclododecane-N,N ,N ,N-tetraacetic acid0-D-Phe1,Tyr3]octreotide (DOT-ATOC) in the meningioma and the high grade glioma (HGG) and a feasibility study of the RGS technique in these cases. Such estimates are performed assuming the use of a β − probe with a sensitive area of 2.55 mm radius, that is under development, to detect 0.1ml residuals. Methods: the uptake and the background from healthy tissues were estimated on 68 Ga-DOTATOC PET scans of 11 meningioma and 12 HGG patients. A dedicated statistical analysis of the DICOM images was developed and validated. The feasibility study was performed by means of a full simulation of the emission and detection of the radiation, accounting for the measured uptake and background rate. Results: all meningioma patients but one with an atypical extracranial tumor showed a very high uptake of DOTATOC. In terms of feasibility of the RGS technique, we estimated that by administering 3 MBq/kg of radio-tracer, the time needed to detect a 0.1 ml remnant at 95% C.L. is smaller than 1 s. Actually, to achieve a detection time of 1 s the required activities to administer are as low as 0.2-0.5 MBq/kg in a large fraction of the patients. In case of HGGs, the uptake is lower, but the tumor-to-non-tumor ratio is higher than four, which implies that it can still be effective for RGS. It was estimated that by administering 3 MBq of radio-tracer, the time needed to detect a 0.1 ml remnant at 95% C.L. is smaller than 6 s with the exception of the only oligodendrioma in the sample. Conclusion: The uptake of 90 Y-DOTATOC in meningioma is high in all studied patients. As far as HGG is concerned, albeit the uptake is significantly worse, it is still acceptable for RGS, in particular if further R&D is made to improve the performances of the β − probe.

arXiv: Medical Physics, 2016

Charged Particle Therapy is a technique for cancer treatment that exploits hadron beams, mostly p... more Charged Particle Therapy is a technique for cancer treatment that exploits hadron beams, mostly protons and carbons. A critical issue is the monitoring of the dose released by the beam to the tumor and to the surrounding tissues. We present the design of a new tracking device for monitoring on-line the dose in ion therapy through the detection of secondary charged particles produced by the beam interactions in the patient tissues. In fact, the charged particle emission shape can be correlated with the spatial dose release and the Bragg peak position. The detector uses the information provided by 12 layers of scintillating fibers followed by a plastic scintillator and a small calorimeter made of a pixelated Lutetium Fine Silicate crystal. Simulations have been performed to evaluate the achievable spatial resolution and a possible application of the device for the monitoring of the dose profile in a real treatment is presented.

Physica Medica

The aim of this work was to assess the performance of a prototype compact gamma camera (MediPROBE... more The aim of this work was to assess the performance of a prototype compact gamma camera (MediPROBE) based on a CdTe semiconductor hybrid pixel detector, for coded aperture imaging. This probe can be adopted for various tasks in nuclear medicine such as preoperative sentinel lymph node localization, breast imaging with 99m Tc radiotracers and thyroid imaging, and in general in radioguided surgery tasks. The hybrid detector is an assembly of a 1-mm thick CdTe semiconductor detector bump-bonded to a photon-counting CMOS readout circuit of the Medipix2 series or energy-sensitive Timepix detector. MediPROBE was equipped with a set of two coded aperture masks with 0.07-mm or 0.08-mm diameter holes. We performed laboratory measurements of field of view, system spatial resolution, and signal-difference-to-noise ratio, by using gamma-emitting radioactive sources (109 Cd, 125 I, 241 Am, 99m Tc). The system spatial resolution in the lateral direction was 0.56 mm FWHM (coded aperture mask with holes of 0.08 mm and a 60 keV source) at a source-collimator distance of 50 mm and a field of view of 40 mm by side. Correspondingly, the longitudinal resolution in 3D source localization tasks was about 3 mm. MediPROBE showed a significant improvement in terms of spatial resolution when equipped with the high-resolution coded apertures, with respect to the performance previously reported with 1-2 mm pinhole apertures as well as with respect to adopting a 0.35 mm pinhole aperture.

IFMBE Proceedings, 2009

In the framework of a research project for breast Computed Tomography (CT), we studied two differ... more In the framework of a research project for breast Computed Tomography (CT), we studied two different flatfield correction methods for a single photon counting (SPC) semiconductor pixel detector for X-ray CT. The first method is the usual flat field irradiation procedure with a uniform exposure of the detector in air, while the second method uses flat field images obtained by interposing attenuating sheets of material (e.g. Al, PMMA) between the X-ray tube and the detector, in order to account for the beam hardening effect that occurs when imaging a sample in CT. In fact, this effect causes a different detector response than with free-in-air flood irradiations. The experimental setup includes a Medipix2 SPC silicon pixel detector (matrix of 256×256 square pixels of 55 μm pitch) and a micro-focus X-ray tube with a molybdenum anode and a focal spot size of 35 μm. The single photon counting operation of Medipix2 avoids integration of dark current and enables energy discrimination in each pixel, allowing noise rejection and providing high signal to noise ratio. With 13- bit/pixel and a count rate exceeding 105 cps/pixel, the detector permits high flux exposures. We present here two sets of tomographic images of PMMA (1.19 g/cm3) phantoms containing water or high density polyethylene (0.95 g/cm3) as contrast materials. For each set of projections we performed the two types of correction before the tomographic reconstruction. Images are compared in terms of contrast-to-noise ratio.

by Luca Piersanti, F. Collamati, A. Pepe, F. Bellini, Valerio Bocci, Marta Cremonesi, S. Morganti, M. Senzacqua, Davide Pinci, Ilaria Mattei, Paola Maria Frallicciardi, and Alessio Sarti

Journal of Nuclear Medicine, 2014

A novel radioguided surgery (RGS) technique for cerebral tumors using β − radiation is being deve... more A novel radioguided surgery (RGS) technique for cerebral tumors using β − radiation is being developed. Checking for a radiotracer that can deliver a β − emitter to the tumor is a fundamental step in the deployment of such a technique. This paper reports a study of the uptake of 90 Y-DOTATOC in meningiomas and high-grade gliomas (HGGs) and a feasibility study of the RGS technique in these types of tumor. Estimates were performed assuming the use of a β − probe under development with a sensitive area 2.55 mm in radius to detect 0.1-mL residuals. Methods: Uptake and background from healthy tissues were estimated on 68 Ga-DOTATOC PET scans of 11 meningioma patients and 12 HGG patients. A dedicated statistical analysis of the DICOM images was developed and validated. The feasibility study was performed using full simulation of emission and detection of the radiation, accounting for the measured uptake and background rate. Results: All meningioma patients but one with an atypical extracranial tumor showed high uptake of DOTATOC. In terms of feasibility of the RGS technique, we estimated that by administering a 3 MBq/kg activity of radiotracer, the time needed to detect a 0.1-mL remnant with 5% false-negative and 1% falsepositive rates is less than 1 s. Actually, to achieve a detection time of 1 s the required activities to administer were as low as 0.2-0.5 MBq/kg in many patients. In HGGs, the uptake was lower than in meningiomas, but the tumor-to-nontumor ratio was higher than 4, which implies that the tracer can still be effective for RGS. It was estimated that by administering 3 mBq/kg of radiotracer, the time needed to detect a 0.1-mL remnant is less than 6 s, with the exception of the only oligodendroma in the sample. Conclusion: Uptake of 90 Y-DOTATOC in meningiomas was high in all studied patients. Uptake in HGGs was significantly worse than in meningiomas but was still acceptable for RGS, particularly if further research and development are done to improve the performance of the β − probe.

In this work we present the study of applicability of a desktop size radiographic/tomographic X-r... more In this work we present the study of applicability of a desktop size radiographic/tomographic X-ray system for real-time microscopy and micro-tomography in the fields of biology, entomology, botanic and medical imaging. The apparatus is made up of the single photon counting pixel silicon detector, Medipix2 (matrix of 256×256 square pixels of 55 μm pitch) and a microfocus X-ray tube with a minimum spot size of 5 μm and a tungsten anode. The system has been used for observations of time-dependent processes inside living and still biological and organic samples. Excellent contrast and spatial resolution (micrometer scale) were obtained as a combination of a) low photon energy (40 kVp X-ray tube voltage), b) single photon counting operation, witch avoids integration of dark current c) energy discrimination in each pixel, allowing noise rejection and providing high SNR, d) high effective dynamic range for long exposures, which allows for high signal with high SNR, e) implementation of an original procedure for the energy response calibration of each pixel of the detector matrix, f) high speed read-out hardware and software, which opens the possibility to perform real-time studies of biological processes permitting, e.g., observation of morphological changes, mutations or metamorphosis of living animals and plants. Static and dynamic images of a parasite life cycle from the larva stage to pupa stage are presented here, as well as an in vivo computed tomography of the parasite living inside its host.

Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment, 2009

An X-ray micro-radiographic system based on the Medipix2 semiconductor pixel detector for dynamic... more An X-ray micro-radiographic system based on the Medipix2 semiconductor pixel detector for dynamic high spatial resolution and for high contrast imaging has been developed. Our system is based on a micro-focus and nano-focus X-ray tube and the hybrid single-photon counting silicon pixel detector Medipix2 (matrix 256×256 sq. pixels of 55 μm pitch). This compact table-top system stands promising as a new tool in the field of small animal imaging as well as in the in-vivo observation of dynamic processes inside living organisms. The main advantages of these Medipix2 pixel detectors include: high sensitivity to low-energy X-ray photons; position sensitive and noiseless single-photon detection with preselected photon energies; single-quantum counting in each pixel performed by digital counter (therefore there is no dark current); digital integration (providing unlimited dynamic range and absolute linearity in device response to number of photons, high sensitivity and high contrast); real-time digital information, high-speed digital communication and data transfer. We improve the picture quality with the help of statistical data analysis and extended the calibration of individual pixels response. 2D and 3D radiographic images of samples demonstrate the potential and applicability of our system for precise in-vivo X-ray high-resolution dynamic diagnostic and biological studies. Obtained results are shown on small animal and organic samples.

Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment, 2009

This work presents a direct comparison of two pixel detectors: a charge-integrating flat panel im... more This work presents a direct comparison of two pixel detectors: a charge-integrating flat panel imager coupled to a CsI:Tl scintillator and a hybrid silicon detector of Medipix2 type, working in a single-photon counting mode. The comparison concerns image quality in terms of system-spatial resolution, signal-to-noise ratio and contrast in imaging of small biological objects. It will be shown that, at photon energies below 40 keV and for low attenuating biological objects, single-photon counting detectors are more appropriate for small-animal imaging than flat panel devices right due to better spatial resolution, signal-to-noise ratio and contrast.

Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment, 2007

We describe MediSPECT, a new scanner developed at University and INFN Napoli, for SPECT studies o... more We describe MediSPECT, a new scanner developed at University and INFN Napoli, for SPECT studies on small animals with a small field of view (FOV) and high spatial resolution. The CdTe pixel detector (a 256×256 matrix of 55 μm square pixels) operating in single photon counting for detection of gamma-rays with low and medium energy (e.g. 125I, 27–35 keV, 99mTc, 140 keV), is bump bonded to the Medipix2 readout chip. The FOV of the MediSPECT scanner with a coded aperture mask collimator ranges from 6.3 mm (system spatial resolution 110 μm at 27–35 keV) to 24.3 mm. With a 0.30 mm pinhole the FOV ranges from 2.4 to 29 mm (where the system spatial resolution is 1.0 mm at 27–35 keV and 2.0 mm at 140 keV). MediSPECT will be used for in vivo imaging of small organs or tissue structures in mouse, e.g., brain, thyroid, heart or tumor.

Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment, 2007

We report on the tests of a prototype (MediSPECT) system developed at University & INFN Napoli, f... more We report on the tests of a prototype (MediSPECT) system developed at University & INFN Napoli, for Single Photon Emission Computed Tomography (SPECT) imaging on small animals with a small Field of View (FoV) and high spatial resolution. MediSPECT is a SPECT imaging system based on a 1-mm-thick CdTe pixel detector, bump-bonded to the Medipix2 CMOS readout circuit operating in single-photon counting. The CdTe detector has 256×256 square array of pixels arranged with a 55 μm pitch, for a sensitive area of 14×14 mm2. In its present version, this system implements a single detector head, mounted on a rotating gantry. For preliminary testing and calibration of the acquisition equipment and image reconstruction algorithms, 90 projections of a γ-ray point source (109Cd) through a single pinhole (diameter 0.4 mm; radius of rotation about 2.5 cm; focal length about 4.5 cm) were acquired for 20 min each in a step-and-shoot mode. Capillaries, 800 μm in diameter, were arranged in a Y-shape to form a more complex phantom (125I, 1 mm pinhole diameter, 45 projections, each acquired for 25 min). Images were reconstructed with a custom algorithm implementing standard OS-EM with center of rotation correction and spatial resolution of 0.2 mm over a FoV of 2 mm was obtained.