Pub Date : 2012-10-01DOI: 10.1109/NSSMIC.2012.6551876
S. Metzler, S. Moore, Mi-Ae Park
We have studied the impact of using rectangular-aperture pinholes in a multi-pinhole, stationary system for cardiac imaging of mice. The system will utilize the standard NaI(TI) detectors on a clinical SPECT system. There are at least two advantages to using rectangular apertures: (1) the fields of view (FOV) in the axial and transverse directions become separable since they are determined by the walls of the aperture insert, which can have independent acceptance angles; and (2) the tiling of projections onto the detector is more efficient for the same solid angle (i.e., allows more pinholes) than traditional, circular apertures since the circular-aperture projections have a packing fraction of less than π/4. The system design places these rectangular apertures, which will be cast using a Pt/Ir alloy that is denser and harder than gold, into a tungsten-polymer tube that will be cast from a mold that is 3D printed in plastic. This fabrication technique will provide flexibility in the placement and orientation of the pinhole inserts yet will be less expensive to manufacture than traditional machining. The system sensitivity depends on the resolution and FOV; we plan to limit the FOV to a region that accommodates a mouse heart with some margin. We have tested the reconstruction of simulated data, with both point phantoms and the MOBY™ phantom, using an MLEM algorithm and found both good resolution and fidelity throughout the targeted FOV, with good angular sampling. The system can achieve an estimated best system resolution of 0.4 mm with high magnification - before resolution recovery by system modeling during reconstruction - but this operating point would yield low sensitivity. Comparisons with commercial and research systems indicate improved sensitivity at the same resolution.
{"title":"Design of a new small-animal SPECT system based on rectangular pinhole aperture","authors":"S. Metzler, S. Moore, Mi-Ae Park","doi":"10.1109/NSSMIC.2012.6551876","DOIUrl":"https://doi.org/10.1109/NSSMIC.2012.6551876","url":null,"abstract":"We have studied the impact of using rectangular-aperture pinholes in a multi-pinhole, stationary system for cardiac imaging of mice. The system will utilize the standard NaI(TI) detectors on a clinical SPECT system. There are at least two advantages to using rectangular apertures: (1) the fields of view (FOV) in the axial and transverse directions become separable since they are determined by the walls of the aperture insert, which can have independent acceptance angles; and (2) the tiling of projections onto the detector is more efficient for the same solid angle (i.e., allows more pinholes) than traditional, circular apertures since the circular-aperture projections have a packing fraction of less than π/4. The system design places these rectangular apertures, which will be cast using a Pt/Ir alloy that is denser and harder than gold, into a tungsten-polymer tube that will be cast from a mold that is 3D printed in plastic. This fabrication technique will provide flexibility in the placement and orientation of the pinhole inserts yet will be less expensive to manufacture than traditional machining. The system sensitivity depends on the resolution and FOV; we plan to limit the FOV to a region that accommodates a mouse heart with some margin. We have tested the reconstruction of simulated data, with both point phantoms and the MOBY™ phantom, using an MLEM algorithm and found both good resolution and fidelity throughout the targeted FOV, with good angular sampling. The system can achieve an estimated best system resolution of 0.4 mm with high magnification - before resolution recovery by system modeling during reconstruction - but this operating point would yield low sensitivity. Comparisons with commercial and research systems indicate improved sensitivity at the same resolution.","PeriodicalId":187728,"journal":{"name":"2012 IEEE Nuclear Science Symposium and Medical Imaging Conference Record (NSS/MIC)","volume":"49 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123813744","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-10-01DOI: 10.1109/NSSMIC.2012.6551359
C. Royon
We describe the main components of the ATLAS Forward Physics project, namely the movable beam pipe, the tracking and timing detectors which allow to detect intact protons in the final state at the LHC. The position detector is composed on 6 layers of 3D silicon detectors readout by FE-I4 chips developped for ATLAS. The fast timing detector is built from a quartz-based Cerenkov detector coupled to a microchannel plate photomultiplier tube, followed by the electronic elements that amplify, measure, and record the time of the event along with a stabilized reference clock signal, ensuring a time resolution of 10-15 picoseconds.
{"title":"The ATLAS Forward Physics project","authors":"C. Royon","doi":"10.1109/NSSMIC.2012.6551359","DOIUrl":"https://doi.org/10.1109/NSSMIC.2012.6551359","url":null,"abstract":"We describe the main components of the ATLAS Forward Physics project, namely the movable beam pipe, the tracking and timing detectors which allow to detect intact protons in the final state at the LHC. The position detector is composed on 6 layers of 3D silicon detectors readout by FE-I4 chips developped for ATLAS. The fast timing detector is built from a quartz-based Cerenkov detector coupled to a microchannel plate photomultiplier tube, followed by the electronic elements that amplify, measure, and record the time of the event along with a stabilized reference clock signal, ensuring a time resolution of 10-15 picoseconds.","PeriodicalId":187728,"journal":{"name":"2012 IEEE Nuclear Science Symposium and Medical Imaging Conference Record (NSS/MIC)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114345304","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-10-01DOI: 10.1109/NSSMIC.2012.6551151
M. Okihara, H. Kasai, N. Miura, N. Kuriyama, Y. Nagatomo, T. Hatsui, M. Omodani, T. Miyoshi, Y. Arai
We have been developing the 0.2 μm fully-depleted Silicon On Insulator (SOl) CMOS technology for monolithic pixel detectors. In order to improve the sensor's sensitivity, 8 inch FZ wafer is introduced for handle substrate in SO! wafer. Stitching technology is also developed to get large detector chip area. Furthermore, nested well structure for the p-n junction and double-SOI structure are investigating for reducing the radiation damage and crosstalk between electrical circuitry in top silicon layer and sensors at substrate. In this document, recent progress of process technology for pixel detector is described.
{"title":"Progress of FD-SOI technology for monolithic pixel detectors","authors":"M. Okihara, H. Kasai, N. Miura, N. Kuriyama, Y. Nagatomo, T. Hatsui, M. Omodani, T. Miyoshi, Y. Arai","doi":"10.1109/NSSMIC.2012.6551151","DOIUrl":"https://doi.org/10.1109/NSSMIC.2012.6551151","url":null,"abstract":"We have been developing the 0.2 μm fully-depleted Silicon On Insulator (SOl) CMOS technology for monolithic pixel detectors. In order to improve the sensor's sensitivity, 8 inch FZ wafer is introduced for handle substrate in SO! wafer. Stitching technology is also developed to get large detector chip area. Furthermore, nested well structure for the p-n junction and double-SOI structure are investigating for reducing the radiation damage and crosstalk between electrical circuitry in top silicon layer and sensors at substrate. In this document, recent progress of process technology for pixel detector is described.","PeriodicalId":187728,"journal":{"name":"2012 IEEE Nuclear Science Symposium and Medical Imaging Conference Record (NSS/MIC)","volume":"80 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116363801","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-10-01DOI: 10.1109/NSSMIC.2012.6551141
C. Piemonte, A. Ferri, A. Gola, A. Picciotto, T. Pro, N. Serra, A. Tarolli, N. Zorzi
In this paper, we show the analysis software we created for a fast and reliable automatic characterization of a silicon photomultiplier. The program can be used both in dark and under continuous low-level light illumination. It grabs 1ms-long waveforms, each containing many single cell pulses, from an oscilloscope connected to the PC via Ethernet. On-line data analysis is done both on the raw waveform as well as on a filtered (with DLED technique) version in order to facilitate the pulse identification and the extraction of some parameters also in cases of high count rates or cross-talk. The main outcomes of the program are: single-cell signal shape, gain, primary dark count rate, after-pulse probability, direct and delayed cross-talk probability and excess charge factor. It can be used also to determine the actual photo-detection efficiency with the proper hardware set-up.
{"title":"Development of an automatic procedure for the characterization of silicon photomultipliers","authors":"C. Piemonte, A. Ferri, A. Gola, A. Picciotto, T. Pro, N. Serra, A. Tarolli, N. Zorzi","doi":"10.1109/NSSMIC.2012.6551141","DOIUrl":"https://doi.org/10.1109/NSSMIC.2012.6551141","url":null,"abstract":"In this paper, we show the analysis software we created for a fast and reliable automatic characterization of a silicon photomultiplier. The program can be used both in dark and under continuous low-level light illumination. It grabs 1ms-long waveforms, each containing many single cell pulses, from an oscilloscope connected to the PC via Ethernet. On-line data analysis is done both on the raw waveform as well as on a filtered (with DLED technique) version in order to facilitate the pulse identification and the extraction of some parameters also in cases of high count rates or cross-talk. The main outcomes of the program are: single-cell signal shape, gain, primary dark count rate, after-pulse probability, direct and delayed cross-talk probability and excess charge factor. It can be used also to determine the actual photo-detection efficiency with the proper hardware set-up.","PeriodicalId":187728,"journal":{"name":"2012 IEEE Nuclear Science Symposium and Medical Imaging Conference Record (NSS/MIC)","volume":"131 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121540845","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-10-01DOI: 10.1109/NSSMIC.2012.6551056
Andrew Parker, C. Boxall, M. Joyce, P. Schotanus
The specification, design, and initial measurements of a thallium-doped sodium-iodide well-type scintillator for the principle use in detecting 40K concentrations in open-source potassium chloride aqueous solutions is discussed. The hazards, safety concerns and radwaste generation associated with using open-source radioactive isotopes present significant difficulties and costs to radioanalytical laboratory research. A solution to this is the use of non-hazardous alternatives - which mimic notable fission products (137Cs) - that can be utilised as reliable and safe substitutes. In this paper a scintillator detector designed to detect the active isotope present in potassium chloride, yet remaining portable for in situ measurements at nuclear sites, is described with preliminary results highlighting its effective use.
{"title":"A NaI(Tl) scintillator for in situ environmental studies and laboratory detection measurements of aqueous potassium chloride","authors":"Andrew Parker, C. Boxall, M. Joyce, P. Schotanus","doi":"10.1109/NSSMIC.2012.6551056","DOIUrl":"https://doi.org/10.1109/NSSMIC.2012.6551056","url":null,"abstract":"The specification, design, and initial measurements of a thallium-doped sodium-iodide well-type scintillator for the principle use in detecting 40K concentrations in open-source potassium chloride aqueous solutions is discussed. The hazards, safety concerns and radwaste generation associated with using open-source radioactive isotopes present significant difficulties and costs to radioanalytical laboratory research. A solution to this is the use of non-hazardous alternatives - which mimic notable fission products (137Cs) - that can be utilised as reliable and safe substitutes. In this paper a scintillator detector designed to detect the active isotope present in potassium chloride, yet remaining portable for in situ measurements at nuclear sites, is described with preliminary results highlighting its effective use.","PeriodicalId":187728,"journal":{"name":"2012 IEEE Nuclear Science Symposium and Medical Imaging Conference Record (NSS/MIC)","volume":" 2","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"113950381","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-10-01DOI: 10.1109/NSSMIC.2012.6551951
P. Fochuk, L. Dyachenko, S. Ostapoy, O. Kopach, A. E. Bolotnikoy, R. James
For the past years much attention has been paid to inclusion elimination in CdZnTe crystals used for radiation detectors. One of the important parts of this is accurate determinations of inclusion size and concentration. Usually researchers create their own software to calculate these parameters from IR transmission images. Therefore it is important to determine the validity of these programs. For this purpose we developed a software environment that can be used to model the real inclusion distribution in the sample volume and then analyze it. It includes two parts: (1) virtual crystal creation with a subsystem of different structural defect parameters such as types, sizes and distribution of defects (dot, linear and plane defects are supported; distributions: uniform, random, Poisson and Gaussian), and (2) IR images recognition to visualize inclusions and other defects created during scanning of actual crystals or generated by the first program. Also, it is possible to view all created defects in the sample in three ways: in the three-dimensional image, in the set of test photos, and in the crystals description file where coordinates and the sizes of all created defects are stored. In the last case we can use the generated set of images for testing of the recognition quality of defects, a threshold under noise characteristics of the pictures, brightness and contrast. In addition the virtual crystal creation program is able to generate the defects with shadow from IR lantern. The recognition program is able to cut off the shadows and helps us to choose the optimal scanning step to minimize the shadows influence. Using the developed software we tested the correctness of our recognition algorithm. Furthermore, it allows for testing the recognition programs developed by other authors, and helps to choose the optimal IR s
{"title":"Software for inclusions recognition and analisys","authors":"P. Fochuk, L. Dyachenko, S. Ostapoy, O. Kopach, A. E. Bolotnikoy, R. James","doi":"10.1109/NSSMIC.2012.6551951","DOIUrl":"https://doi.org/10.1109/NSSMIC.2012.6551951","url":null,"abstract":"For the past years much attention has been paid to inclusion elimination in CdZnTe crystals used for radiation detectors. One of the important parts of this is accurate determinations of inclusion size and concentration. Usually researchers create their own software to calculate these parameters from IR transmission images. Therefore it is important to determine the validity of these programs. For this purpose we developed a software environment that can be used to model the real inclusion distribution in the sample volume and then analyze it. It includes two parts: (1) virtual crystal creation with a subsystem of different structural defect parameters such as types, sizes and distribution of defects (dot, linear and plane defects are supported; distributions: uniform, random, Poisson and Gaussian), and (2) IR images recognition to visualize inclusions and other defects created during scanning of actual crystals or generated by the first program. Also, it is possible to view all created defects in the sample in three ways: in the three-dimensional image, in the set of test photos, and in the crystals description file where coordinates and the sizes of all created defects are stored. In the last case we can use the generated set of images for testing of the recognition quality of defects, a threshold under noise characteristics of the pictures, brightness and contrast. In addition the virtual crystal creation program is able to generate the defects with shadow from IR lantern. The recognition program is able to cut off the shadows and helps us to choose the optimal scanning step to minimize the shadows influence. Using the developed software we tested the correctness of our recognition algorithm. Furthermore, it allows for testing the recognition programs developed by other authors, and helps to choose the optimal IR s","PeriodicalId":187728,"journal":{"name":"2012 IEEE Nuclear Science Symposium and Medical Imaging Conference Record (NSS/MIC)","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124489821","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-10-01DOI: 10.1109/NSSMIC.2012.6551610
Z. Gu, Q. Bao, R. Taschereau, H. Wang, N. Vu, A. Chatziioannou
PETBox4 is a preclinical system dedicated to imaging mice. This system is composed by four detector panels, each made by a 24 × 50 array of 1.825 × 1.825 × 7 mm BGO crystals. The face to face crystal separation of the detectors is 5 cm, generating a 4.5 × 4.5 × 9.4 cm field of view (FOV). The result is a tomograph with a large detection solid angle, which in combination with a wide open energy window achieves high peak detection efficiency (~17%). Despite the small size of the typical imaged subjects, these design features also increase the fraction of accepted crystal and object scattered events, which reduce the overall image signal to noise ratio. In this work, we investigated the system acquisition configuration settings necessary to optimize the NEC (Noise equivalent Counts) and image quality. A Monte Carlo simulation software package was used (GATE) to investigate the different types of events detected as a function of energy window settings and multiple event acceptance policy. This was done for a realistic distribution of activity and attenuation coefficients in the PETBox4 FOV, based on emission data from an in-vivo preclinical PET image from an average sized mouse (30g). Based on the simulations, the NEC rate was optimized for a dual energy window that accepts both low (50-175 keY) and high (410-650 keY) energy events. This indicates that low energy events that are composed mostly from single crystal scatter contribute useful image information, while events in the middle of the energy spectrum (175keV-410keV), tend to include large fractions of crystal backscatter as well as object scatter and do not contribute significantly in data signal to noise ratio. As a result of the same simulations, a new policy for the acceptance of multiple events was introduced, implementing a "KiIlAIl" multiple policy, further improving the NEe. Overall, these two optimization parameters improved the NEC rate by 56%, providing a significant advantage in image signal to noise ratio.
{"title":"Optimization of energy window and multiple event acceptance policy for PETbox4, a high sensitivity preclinical imaging tomograph","authors":"Z. Gu, Q. Bao, R. Taschereau, H. Wang, N. Vu, A. Chatziioannou","doi":"10.1109/NSSMIC.2012.6551610","DOIUrl":"https://doi.org/10.1109/NSSMIC.2012.6551610","url":null,"abstract":"PETBox4 is a preclinical system dedicated to imaging mice. This system is composed by four detector panels, each made by a 24 × 50 array of 1.825 × 1.825 × 7 mm BGO crystals. The face to face crystal separation of the detectors is 5 cm, generating a 4.5 × 4.5 × 9.4 cm field of view (FOV). The result is a tomograph with a large detection solid angle, which in combination with a wide open energy window achieves high peak detection efficiency (~17%). Despite the small size of the typical imaged subjects, these design features also increase the fraction of accepted crystal and object scattered events, which reduce the overall image signal to noise ratio. In this work, we investigated the system acquisition configuration settings necessary to optimize the NEC (Noise equivalent Counts) and image quality. A Monte Carlo simulation software package was used (GATE) to investigate the different types of events detected as a function of energy window settings and multiple event acceptance policy. This was done for a realistic distribution of activity and attenuation coefficients in the PETBox4 FOV, based on emission data from an in-vivo preclinical PET image from an average sized mouse (30g). Based on the simulations, the NEC rate was optimized for a dual energy window that accepts both low (50-175 keY) and high (410-650 keY) energy events. This indicates that low energy events that are composed mostly from single crystal scatter contribute useful image information, while events in the middle of the energy spectrum (175keV-410keV), tend to include large fractions of crystal backscatter as well as object scatter and do not contribute significantly in data signal to noise ratio. As a result of the same simulations, a new policy for the acceptance of multiple events was introduced, implementing a \"KiIlAIl\" multiple policy, further improving the NEe. Overall, these two optimization parameters improved the NEC rate by 56%, providing a significant advantage in image signal to noise ratio.","PeriodicalId":187728,"journal":{"name":"2012 IEEE Nuclear Science Symposium and Medical Imaging Conference Record (NSS/MIC)","volume":"116 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124132420","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-10-01DOI: 10.1109/NSSMIC.2012.6551156
J. Hasi, C. Kenney, C. Da Via, S. Parker, A. Thompson, E. Westbrook
Attenuating materials are employed on synchrotron beam lines to achieve photon flux modulation as well as beam hardening of the x-ray spectrum. In some experiments it is desirable to maintain the intensity of the beam on the sample at a constant value as the current in the synchrotron decays during a fill cycle. This is often done by attenuating the incident beam with a set of discrete, thin foils. To change the amount of material in the beam path typically involves inserting or redrawing a number of foils. The use of discrete foils imposes practical limits on the number of thickness values available as well as the smallest thickness increment. Micro-machined attenuators can avoid these restrictions by offering either continuous variation of the material thickness or through the implementation of a large number of small thickness steps. Through a combination of photolithography and appropriate device geometry sub-micron thickness increments can be fabricated. Device geometries such as staircase, low-angle triangle, and overlapping triangles will be described. Fabrication of these devices by direct micro-machining of materials such as silicon as well as micro-molding of various polymers can be done relatively easily. In addition, by manufacturing a silicon diode into the attenuator the absorbed fraction of the beam can be continuously monitored. By using a feedback loop where the attenuator thickness is varied based on a downstream beam monitor, it should be possible to maintain the photon flux on a sample to vary by less than 0.5%. The performance of a variety of these devices at the Advanced Light Source is presented.
{"title":"Active beam attenuators for synchrotron radiation","authors":"J. Hasi, C. Kenney, C. Da Via, S. Parker, A. Thompson, E. Westbrook","doi":"10.1109/NSSMIC.2012.6551156","DOIUrl":"https://doi.org/10.1109/NSSMIC.2012.6551156","url":null,"abstract":"Attenuating materials are employed on synchrotron beam lines to achieve photon flux modulation as well as beam hardening of the x-ray spectrum. In some experiments it is desirable to maintain the intensity of the beam on the sample at a constant value as the current in the synchrotron decays during a fill cycle. This is often done by attenuating the incident beam with a set of discrete, thin foils. To change the amount of material in the beam path typically involves inserting or redrawing a number of foils. The use of discrete foils imposes practical limits on the number of thickness values available as well as the smallest thickness increment. Micro-machined attenuators can avoid these restrictions by offering either continuous variation of the material thickness or through the implementation of a large number of small thickness steps. Through a combination of photolithography and appropriate device geometry sub-micron thickness increments can be fabricated. Device geometries such as staircase, low-angle triangle, and overlapping triangles will be described. Fabrication of these devices by direct micro-machining of materials such as silicon as well as micro-molding of various polymers can be done relatively easily. In addition, by manufacturing a silicon diode into the attenuator the absorbed fraction of the beam can be continuously monitored. By using a feedback loop where the attenuator thickness is varied based on a downstream beam monitor, it should be possible to maintain the photon flux on a sample to vary by less than 0.5%. The performance of a variety of these devices at the Advanced Light Source is presented.","PeriodicalId":187728,"journal":{"name":"2012 IEEE Nuclear Science Symposium and Medical Imaging Conference Record (NSS/MIC)","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127619339","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Differentiating pathological stages, i.e., hyperplastic (H), tubular adenoma (Ta), tubulovillous adenoma (Va) and adenocarcinoma (A), of detected colon lesions is a main task for computer aided diagnosis (CADx) of polyps for computed tomography colonography (CTC). In this paper, we propose a virtual pathological model of differentiating the polyp types based on the Haralick texture analysis model, which computes various correlations of the image density distribution inside each polyp volume. Our model explores the utility of texture features from higher order differentiations or amplification, i.e., gradient and curvature, of the image density distribution, mimicking the amplification in pathology. The first set of texture features is extracted from the gradient of the image density distribution. The second set of texture features is derived from the curvature of the image density distribution. The gain of these two sets of newly developed higher order texture features was measured using the area under the receiver operating characteristic (ROC) curve (AUC) from a database of 124 lesions (polyps and masses, confirmed by both optical colonoscopy (OC) and CTC). Support vector machine (SVM) is employed for classification. The gain by the two sets new features over the original Haralick texture model is noticeable, i.e., by 15% of improvement of the average AUC by including first set and second set of new texture features for group HvsRest and 11% for group H&TavsRest than the basic Haralick texture features.
{"title":"A feasibility study of high order volumetric texture features for computer aided diagnosis of polyps via CT colonography","authors":"Bowen Song, Guopeng Zhang, Hongbin Zhu, Wei Zhu, Hongbing Lu, Zhengrong Liang","doi":"10.1109/NSSMIC.2012.6551903","DOIUrl":"https://doi.org/10.1109/NSSMIC.2012.6551903","url":null,"abstract":"Differentiating pathological stages, i.e., hyperplastic (H), tubular adenoma (Ta), tubulovillous adenoma (Va) and adenocarcinoma (A), of detected colon lesions is a main task for computer aided diagnosis (CADx) of polyps for computed tomography colonography (CTC). In this paper, we propose a virtual pathological model of differentiating the polyp types based on the Haralick texture analysis model, which computes various correlations of the image density distribution inside each polyp volume. Our model explores the utility of texture features from higher order differentiations or amplification, i.e., gradient and curvature, of the image density distribution, mimicking the amplification in pathology. The first set of texture features is extracted from the gradient of the image density distribution. The second set of texture features is derived from the curvature of the image density distribution. The gain of these two sets of newly developed higher order texture features was measured using the area under the receiver operating characteristic (ROC) curve (AUC) from a database of 124 lesions (polyps and masses, confirmed by both optical colonoscopy (OC) and CTC). Support vector machine (SVM) is employed for classification. The gain by the two sets new features over the original Haralick texture model is noticeable, i.e., by 15% of improvement of the average AUC by including first set and second set of new texture features for group HvsRest and 11% for group H&TavsRest than the basic Haralick texture features.","PeriodicalId":187728,"journal":{"name":"2012 IEEE Nuclear Science Symposium and Medical Imaging Conference Record (NSS/MIC)","volume":"63 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126316354","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2012-10-01DOI: 10.1109/NSSMIC.2012.6551348
S. Clarke, S. Pozzi, E. Padovani
The MCNP-PoliMi code is an enhanced version of the MCNP4c code developed in 2003 to simulate the detector response from correlated neutron and gamma-ray measurements. In 2012 the -PoliMi modifications were incorporated into version 2.7.0 of the MCNPX code. This allows the user to use all of the -PoliMi enhancements in conjunction with the advanced features of the MCNPX code. The MCNPX-PoliMi code has the ability to generate a source file containing the reaction data of all photonuclear reactions occurring in the target material. In addition, a variance reduction option has been implemented whereby the user can read the photonuclear source file multiple times. MCNPX-PoliMi also contains experimentally based models of delayed-neutron emission from photofission reactions. The results presented in the full paper will provide a demonstration of the features of the MCNPX-PoliMi code for active-interrogation scenarios of interest. In particular, the response from uranium will be compared to that of common benign materials.
{"title":"Photonuclear physics modeling in the MCNPX-PoliMi code","authors":"S. Clarke, S. Pozzi, E. Padovani","doi":"10.1109/NSSMIC.2012.6551348","DOIUrl":"https://doi.org/10.1109/NSSMIC.2012.6551348","url":null,"abstract":"The MCNP-PoliMi code is an enhanced version of the MCNP4c code developed in 2003 to simulate the detector response from correlated neutron and gamma-ray measurements. In 2012 the -PoliMi modifications were incorporated into version 2.7.0 of the MCNPX code. This allows the user to use all of the -PoliMi enhancements in conjunction with the advanced features of the MCNPX code. The MCNPX-PoliMi code has the ability to generate a source file containing the reaction data of all photonuclear reactions occurring in the target material. In addition, a variance reduction option has been implemented whereby the user can read the photonuclear source file multiple times. MCNPX-PoliMi also contains experimentally based models of delayed-neutron emission from photofission reactions. The results presented in the full paper will provide a demonstration of the features of the MCNPX-PoliMi code for active-interrogation scenarios of interest. In particular, the response from uranium will be compared to that of common benign materials.","PeriodicalId":187728,"journal":{"name":"2012 IEEE Nuclear Science Symposium and Medical Imaging Conference Record (NSS/MIC)","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126531404","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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