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17th International Workshop on Radiation Imaging Detectors

作者： Naimuddin, Md. Coutrakon, G. Blazey, G. Boi, S. Dyshkant, A. Erdelyi, B. Hedin, D. Johnson, E. Krider, J. Rukalin, V. Uzunyan, S. A. Zutshi, V. Fordt, R. Sellberg, G. Rauch, J. E. Roman, M. Rubinov, P. Wilson, P. Univ Delhi Dept Phys & Astrophys Delhi 110007 India No Illinois Univ Dept Phys De Kalb IL 60115 USA Fermilab Natl Accelerator Lab POB 500 Batavia IL 60510 USA

computer tomography is one of the most promising new methods to image abnormal tissues inside the human body. Tomography is also used to position the patient accurately before radiation therapy. Hadron therapy for treating cancer has become one of the most advantegeous and safe options. In order to fully utilize the advantages of hadron therapy, there is a necessity of performing radiography with hadrons as well. In this paper we present the development of a proton computed tomography system. Our second-generation proton tomography system consists of two upstream and two downstream trackers made up of fibers as active material and a range detector consisting of plastic scintillators. We present details of the detector system, readout electronics, and data acquisition system as well as the commissioning of the entire system. We also present preliminary results from the test beam of the range detector.

关键词： Instrumentation for hadron therapy computerized Tomography (CT) and Computed Radiography (CR) medical-image reconstruction methods and algorithms, computer-aided software

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Assessment of the effects of different sample perfusion procedures on phase-contrast tomographic images of mouse spinal cord

Assessment of the effects of different sample perfusion proc...

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International Workshop on Imaging II

作者： Stefanutti, E. Sierra, A. Miocchi, P. Massimi, L. Brun, F. Maugeri, L. Bukreeva, I. Nurmi, A. Provinciali, G. Begani Tromba, G. Grohn, O. Giove, F. Cedola, A. Fratini, M. IRCCS Fdn Santa Lucia Via Ardeatina 306-354 I-00142 Rome Italy Univ Eastern Finland Biomed Imaging Unit AI Virtanen Inst Mol Sci Neulaniementie 2 FIN-70211 Kuopio Finland Sapienza Univ CNR Inst Nanotechnol Phys Dept Piazzale Aldo Moro 2 I-00185 Rome Italy Charles River Discovery Serv Microkatu 1 Kuopio 70210 Finland Sapienza Univ Phys Dept Piazzale Aldo Moro 2 I-00185 Rome Italy Elettra Synchrotron Radiat Trieste SCpA Area Sci Pk I-34149 Trieste Italy Museo Stor Fis Ctr Fermi Piazza Viminale 1 I-00184 Rome Italy Ctr Studi & Ric Enrico Fermi Piazza Viminale 1 I-00184 Rome Italy

Synchrotron X-ray Phase Contrast micro-Tomography (SXrPC mu T) is a powerful tool in the investigation of biological tissues, including the central nervous system (CNS), and it allows to simultaneously detect the vascular and neuronal network avoiding contrast agents or destructive sample preparations. However, specific sample preparation procedures aimed to optimize the achievable contrast-and signal-to-noise ratio (CNR and SNR, respectively) are required. Here we report and discuss the effects of perfusion with two different fixative agents (ethanol and paraformaldehyde) and with a widely used contrast medium (MICROFIL (R)) on mouse spinal cord. As a main result, we found that ethanol enhances contrast at the grey/white matter interface and increases the contrast in correspondence of vascular features and fibres, thus providing an adequate spatial resolution to visualise the vascular network at the microscale. On the other hand, ethanol is known to induce tissue dehydration, likely reducing cell dimensions below the spatial resolution limit imposed by the experimental technique. Nonetheless, neurons remain well visible using either perfused paraformaldehyde or MICROFIL (R) compound, as these latter media do not affect tissues with dehydration effects. Paraformaldehyde appears as the best compromise: it is not a contrast agent, like MICROFIL (R), but it is less invasive than ethanol and permits to visualise well both cells and blood vessels. However, a quantitative estimation of the relative grey matter volume of each sample has led us to conclude that no significant alterations in the grey matter extension compared to the white matter occur as a consequence of the perfusion procedures tested in this study.

关键词： medical-image reconstruction methods and algorithms, computer-aided diagnosis medical-image reconstruction methods and algorithms, computer-aided software

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Preliminary evaluation of a monolithic detector module for integrated PET/MRI scanner with high spatial resolution

Preliminary evaluation of a monolithic detector module for i...

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16th International Workshop on Radiation Imaging Detectors

作者： Pani, R. Gonzalez, A. J. Bettiol, M. Fabbri, A. Cinti, M. N. Preziosi, E. Borrazzo, C. Conde, P. Pellegrini, R. Di Castro, E. Majewski, S. Univ Roma La Sapienza Dept Mol Med I-00185 Rome Italy CSIC I3M Valencia 46022 Spain Univ Roma La Sapienza Postgrad Sch Med Phys I-00185 Rome Italy Univ Roma La Sapienza SAIMLAL Dept Doctorate Sch Biol & Mol Med Morphofunct Sci Biophys I-00185 Rome Italy Univ Roma La Sapienza Dept Radiol Sci Oncol & Pathol I-00185 Rome Italy W Virginia Univ Dept Radiol Ctr Adv Imaging Morgantown WV 26506 USA

The proposal of Mindview European Project concerns with the development of a very high resolution and high efficiency brain dedicated PET scanner simultaneously working with a Magnetic Resonance scanner, that expects to visualize neurotransmitter pathways and their disruptions in the quest to better diagnose schizophrenia. On behalf of this project, we propose a low cost PET module for the first prototype, based on monolithic crystals, suitable to be integrated with a head Radio Frequency (RF) coil. The aim of the suggested module is to achieve high performances in terms of efficiency, planar spatial resolution (expected about 1 mm) and discrimination of gamma Depth Of Interaction (DOI) in order to reduce the parallax error. Our preliminary results are very promising: a DOI resolution of about 3 mm, a spatial resolution ranging from about 1 to 1.5 mm and a good position linearity.

关键词： Gamma camera, SPECT, PET PET/CT, coronary CT angiography (CTA) medical-image reconstruction methods and algorithms, computer-aided software Multi-modality systems

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Signal to Noise Ratio optimization for extended sources with a new kind of MURA masks

Signal to Noise Ratio optimization for extended sources with...

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21st International Workshop on Radiation Imaging Detectors

作者： Kaissas, I. Papadimitropoulos, C. Clouvas, A. Potiriadis, C. Lambropoulos, C. P. Greek Atom Energy Commiss Patriarchou Grigoriou & Neapoleos Attiki 15341 Greece Aristotle Univ Thessaloniki Sch Elect & Comp Engn Univ Campus Thessaloniki 54124 Greece Natl & Kapodistrian Univ Athens Athens Greece

Using coded aperture, for localization of radioactive hot-spots, results in enhanced efficiency and under certain configurations wide Field of View (FOV). We present a coded aperture assembly technique which can be restructured easily, as well as the reduction of the intrinsic noise of coded apertures constructed with this technique, when they localize spatially extended gamma-emitters. Specifically, Modified-Uniformly-Redundant-Array (MURA) coded apertures are structured by embedding lead spheres in a matrix of positions machined inside a transparent medium such as acrylic glass, resulting in an advantageous transparent to opaque area ratio and thus an improved detection efficiency. This configuration also induces a systematic, element-wise, noise on the Point-Spread-Function (PSF) of the correlation matrix. When imaging with these apertures extended hot-spots, a penumbra phenomenon occurrs and reduces this intrinsic noise, in the way a kernel filter does. Fast-Fourier-Transform (FFT) is used to analyze the effect of this phenomenon on the correlation matrix and to explain the maximization of its Signal-to-Noise Ratio (SNR) for certain extent of the hot-spots. Simulations have been used for the detailed study of the SNR dependence on the dimensions of the hot-spot, while experiments with two Tc-99m cylindrical sources with 11mm and 24mm diameter, respectively and 1.5MBq activity each, confirm the reduction of the intrinsic noise. The results define the way of optimization of the imaging setup for the detection of extended hot-spots. Such an optimization could be useful for example in the case of lymph nodes or thyroid remnant imaging in nuclear medicine. Finally, we propose a kernel filter, derived by the Auto-Correlation-Function (ACF), to be applied on PSFs with high intrinsic noise, in order to eliminate it.

关键词： image filtering Intra-operative probes medical-image reconstruction methods and algorithms, computer-aided software Search for radioactive and fissile materials

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Position algorithm for monolithic scintillation crystals based on charge projection readout

Position algorithm for monolithic scintillation crystals bas...

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17th International Workshop on Radiation Imaging Detectors

作者： Pani, R. Bettiol, M. Preziosi, E. Cinti, M. N. Borrazzo, C. Pellegrini, R. Di Castro, E. Fabbri, A. Univ Roma La Sapienza Dept Sci & Med & Surg Biotechnol Piazzale Aldo Moro 5 I-00185 Rome Italy Univ Roma La Sapienza Dept Mol Med Piazzale Aldo Moro 5 I-00185 Rome Italy Univ Roma La Sapienza Morphofunct Sci Biophys Doctorate Sch Biol & Mol Med SAIMLAL Dept Piazzale Aldo Moro 5 I-00185 Rome Italy Univ Roma La Sapienza Post Grad Sch Med Phys Piazzale Aldo Moro 5 I-00185 Rome Italy Univ Roma La Sapienza Dept Radiol Sci Oncol & Pathol Piazzale Aldo Moro 5 I-00185 Rome Italy

Nuclear medicine imaging devices commonly use multi-element photo detection systems, composed of an array of N x N elements, each one providing an individual signal. Many strategies have been developed to reduce the number of readout channels, one of the main approaches is the Rows and Columns (R/C) projection logic. In this paper we proposed a modified version of Raised To the Power (RTP) algorithm adapted to R/C logic. In order to validate its efficiency a linear scanning irradiation on two 49 x 49 mm(2) LaBr3:Ce (0.5%) crystals with different thickness (4 mm and 10 mm) was carried out. Imaging performance analysis was made in terms of position linearity, Field-of-View (FoV) enlargement and spatial resolution. Imaging results from Anger Logic, RTP algorithm based on single element readout and RTP algorithm based on R/C readout were compared. A notable advantage of using RTP algorithms instead of Anger Logic was found: the FoV widens from about 30% to more than 70% of the detector area whereas the spatial resolution is highly improved, especially for off-center interactions, both for 4 mm-thick and 10 mm-thick crystals. Furthermore, imaging performance with the R/C readout is just slightly different from the single element one (FoV reduction less than 7% and SR worsening less than 10%). The R/C adapted RTP algorithm opens doors to high imaging performance with a substantial reduction of complexity and cost in the readout electronics.

关键词： Gamma camera, SPECT, PET PET/CT, coronary CT angiography (CTA) medical-image reconstruction methods and algorithms, computer-aided software

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Analytic digital tomosynthesis reconstruction in partial sampling with a multislit collimator using a prior sinogram interpolation method

Analytic digital tomosynthesis reconstruction in partial sam...

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20th International Workshop on Radiation Imaging Detectors

作者： Park, S. Kim, G. Park, C. Lee, D. Cho, H. Kim, K. Kang, S. Kim, W. Lim, H. Lee, H. Jeon, D. Park, J. Lim, Y. Seo, C. Yonsei Univ iTOMO Grp Dept Radiat Convergence Engn 1 Yonseidae Gil Wonju 26493 Gangwon Do South Korea

This study investigated analytic digital tomosynthesis (DTS) reconstruction in partial sampling with a multislit collimator that partially blocks the x-ray beam to the patient during projection data acquisition, thereby reducing excessive radiation dose to patients. Partially-sampled DTS images reconstructed using the analytic filtered-backprojection (FBP) algorithm usually suffer from severe bright-band artifacts around multislit edges of the collimator due to incomplete spatial sampling. In this study, a new prior sinogram interpolation method was introduced to the analytic DTS reconstruction in partial sampling to alleviate such artifacts. To verify the proposed DTS method, we conducted a systematic simulation and investigated image characteristics. Three multislit collimator layouts of C(2/2), C(3/3), and C(4/4) with a 50% duty cycle were designed and used in the simulation. Here C(n/n) denotes a collimator layout that blocks the x-ray beam over n detector pixels vertically with a n-pixel interval. All projections were obtained at a tomographic angle of theta = +/- 40 degrees and an angle step of Delta theta = 2 degrees and used to reconstruct DTS images using the FBP algorithm. Our results indicate that the proposed sinogram interpolation method effectively minimized bright-band artifacts in analytic DTS reconstruction in partial sampling, thus maintaining the image quality.

关键词： computerized Tomography (CT) and Computed Radiography (CR) medical-image reconstruction methods and algorithms, computer-aided software

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Using triple gamma coincidences with a pixelated semiconductor Compton-PET scanner: a simulation study

Using triple gamma coincidences with a pixelated semiconduct...

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17th International Workshop on Radiation Imaging Detectors

作者： Kolstein, M. Chmeissani, M. Barcelona Inst Sci & Technol IFAE Campus UAB E-08193 Bellaterra Barcelona Spain

The Voxel Imaging PET (VIP) Pathfinder project presents a novel design using pixelated semiconductor detectors for nuclear medicine applications to achieve the intrinsic image quality limits set by physics. The conceptual design can be extended to a Compton gamma camera. The use of a pixelated CdTe detector with voxel sizes of 1 x 1 x 2mm(3) guarantees optimal energy and spatial resolution. However, the limited time resolution of semiconductor detectors makes it impossible to use Time Of Flight (TOF) with VIP PET. TOF is used in order to improve the signal to noise ratio (SNR) by using only the most probable portion of the Line-Of-Response (LOR) instead of its entire length. To overcome the limitation of CdTe time resolution, we present in this article a simulation study using beta(+)-gamma emitting isotopes with a Compton-PET scanner. When the beta(+) annihilates with an electron it produces two gammas which produce a LOR in the PET scanner, while the additional gamma, when scattered in the scatter detector, provides a Compton cone that intersects with the aforementioned LOR. The intersection indicates, within a few mm of uncertainty along the LOR, the origin of the beta-gamma decay. Hence, one can limit the part of the LOR used by the image reconstruction algorithm.

关键词： Gamma camera, SPECT, PET PET/CT, coronary CT angiography (CTA) Multi-modality systems medical-image reconstruction methods and algorithms, computer-aided software Compton imaging

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Proton Computed Tomography: iterative image reconstruction and dose evaluation

Proton Computed Tomography: iterative image reconstruction a...

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18th International Workshop on Radiation Imaging Detectors

作者： Civinini, C. Bonanno, D. Brianzi, M. Carpinelli, M. Cirrone, G. A. P. Cuttone, G. Lo Presti, D. Maccioni, G. Pallotta, S. Randazzo, N. Scaringella, M. Romano, F. Sipala, V. Talamonti, C. Vanzi, E. Bruzzi, M. Ist Nazl Fis Nucl Florence Div Florence Italy Ist Nazl Fis Nucl Catania Div Catania Italy Ist Nazl Fis Nucl Lab Nazl Sud Catania Italy Univ Sassari Chem & Pharm Dept Sassari Italy Univ Catania Dept Phys & Astron Catania Italy Ist Nazl Fis Nucl Cagliari Div Cagliari Italy Univ Florence Biomed Expt & Clin Sci Dept Florence Italy Azienda Osped Univ Careggi SOD Fis Med Florence Italy Azienda Osped Univ Senese Fis Sanit Siena Italy Univ Florence Dept Phys & Astron Florence Italy

Proton Computed Tomography (pCT) is a medical imaging method with a potential for increasing accuracy of treatment planning and patient positioning in hadron therapy. A pCT system based on a Silicon microstrip tracker and a YAG:Ce crystal calorimeter has been developed within the INFN Prima-RDH collaboration. The prototype has been tested with a 175 MeV proton beam at The Svedberg Laboratory (Uppsala, Sweden) with the aim to reconstruct and characterize a tomographic image. Algebraic iterative reconstruction methods (ART), together with the most likely path formalism, have been used to obtain tomographies of an inhomogeneous phantom to eventually extract density and spatial resolutions. These results will be presented and discussed together with an estimation of the average dose delivered to the phantom and the dependence of the image quality on the dose. Due to the heavy computation load required by the algebraic algorithms the reconstruction programs have been implemented to fully exploit the high calculation parallelism of Graphics Processing Units. An extended field of view pCT system is in an advanced construction stage. This apparatus will be able to reconstruct objects of the size of a human head making possible to characterize this pCT approach in a pre-clinical environment.

关键词： Instrumentation for hadron therapy Instrumentation for particle-beam therapy medical-image reconstruction methods and algorithms, computer-aided software

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GATE simulation of a new design of pinhole SPECT system for small animal brain imaging

GATE simulation of a new design of pinhole SPECT system for ...

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14th Topical Seminar on Innovative Particle and Radiation Detectors

作者： Ozsahin, D. Uzun Blackberg, L. El Fakhri, G. Sabet, H. Harvard Med Sch Massachusetts Gen Hosp Dept Radiol 55 Fruit St Boston MA 02115 USA Near East Univ TRNC Dept Biomed Engn Near East Blvd CY-99138 Nicosia Cyprus Uppsala Univ Dept Phys & Astron Box 516 SE-75120 Uppsala Sweden

Small animal SPECT imaging has gained an increased interest over the past decade since it is an excellent tool for developing new drugs and tracers. Therefore, there is a huge effort on the development of cost-effective SPECT detectors with high capabilities. The aim of this study is to simulate the performance characteristics of new designs for a cost effective, stationary SPECT system dedicated to small animal imaging with a focus on mice brain. The conceptual design of this SPECT system platform, Stationary Small Animal SSA-SPECT, is to use many pixelated CsI:TI detector modules with 0.4 mm x 0.4 mm pixels in order to achieve excellent intrinsic detector resolution where each module is backed by a single pinhole collimator with 0.3 mm hole diameter. In this work, we present the simulation results of four variations of the SSA-SPECT platform where the number of detector modules and FOV size is varied while keeping the detector size and collimator hole size constant. Using the NEMA NU-4 protocol, we performed spatial resolution, sensitivity, image quality simulations followed by a Derenzo-like phantom evaluation. The results suggest that all four SSA-SPECT systems can provide better than 0.063% system sensitivity and < 1.5 mm FWHM spatial resolution without resolution recovery or other correction techniques. Specifically, SSA-SPECT-1 showed a system sensitivity of 0.09% in combination with 1.1 mm FWHM spatial resolution.

关键词： Detector modelling and simulations I (interaction of radiation with matter, interaction of photons with matter, interaction of hadrons with matter, etc) Gamma camera, SPECT, PET PET/CT, coronary CT angiography (CTA) Gamma detectors (scintillators, CZT, HPG, HgI etc) medical-image reconstruction methods and algorithms, computer-aided software

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Impact of uterine deformation induced by applicator on brachytherapy dosimetric value: an uterine-mimicking-phantom study

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JOURNAL OF INSTRUMENTATION 2023年第8期18卷 P08027页

作者： Seiri, Mahnaz Jaberi, Ramin Solgi, Razieh Shakeri, Mahsa Ghadiri, Hossein Univ Tehran Med Sci Sch Med Dept Med Phys & Biomed Engn Tehran Iran Univ Tehran Med Sci Adv Med Technol & Equipment Inst Res Ctr Mol & Cellular Imaging RCMCI Tehran Iran Univ Tehran Med Sci Preclin Core Facil Tehran Iran Univ Tehran Med Sci Canc Inst Radiat Oncol Res Ctr RORC Tehran Iran Univ Surrey Dept Phys Guildford England

Brachytherapy (BT) is subjected to uncertainties from imaging, treatment planning, and anatomical variations. It is necessary to identify the uncertainties, their magnitude, and their impact on the overall uncertainty of dose delivery. The aim of the present phantom-based study is to investigate the deformation of the uterus anatomy induced by BT applicator insertion and the relationship between dose and location of the inserted applicator. A novel flexible phantom was designed based on female pelvic anatomy by the 3D printing process to simulate the deformation and movement of the uterine during the BT process. The applicator was inserted into the uterus and in order to simulate the uterus motion, the phantom was moved in four directions, right, left, down, and up. The CT and ultrasound images were obtained. A two-stage registration algorithm was designed to register the ultrasound and CT images in order to calculate the applicator displacements map. This map was used to calculate delivered dose error to uterus and rectum and to correct the planned dose values in treatment planning procedure. The results showed that in a planned D90 (dose) of 9.4 Gy for the uterus and maximum dose of 1.8 Gy to the rectum, movement of applicator leads to a big deviation in final delivered doses. After the applicator moved to the right and left directions, the D90 delivered to the uterus was 6.2 Gy and 5.6 Gy, respectively. Moreover, by moving downwards and upwards, the uterus received 0.4 and 1.2 Gy lower than 9.4 Gy. Similarly, the maximum dose to the rectum in right, left, down, and up directions after applicator movement were 3.4 Gy, 3.3 Gy, 3.7 Gy and 3.2 Gy, respectively which highlighted the higher delivered dose to the rectum. The results of the study demonstrate that applicator displacement can lead to uterine underdosing and also increase the risk of rectum irradiation. Ultimately, image-guided brachytherapy and using image registration can increase the accuracy of treatmen

关键词： algorithms and software for radiotherapy Multi-modality systems Radiotherapy concepts medical-image reconstruction methods and algorithms, computer-aided software

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