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A feasibility study for anatomical noise reduction in dual-energy chest digital tomosynthesis

JOURNAL OF INSTRUMENTATION 2016年第1期11卷 P01016-P01016页

作者： Lee, D. Kim, Y. -s. Choi, S. Lee, H. Choi, S. Kim, H. -J. Yonsei Univ Coll Hlth Sci Dept Radiat Convergence Engn 1 Yonseidae Gil Wonju 220710 Gangwon South Korea Yonsei Univ Dept Radiol Sci 1 Yonseidae Gil Wonju 220710 Gangwon South Korea Yonsei Univ Res Inst Hlth Sci 1 Yonseidae Gil Wonju 220710 Gangwon South Korea

Lung cancer is the leading cause of cancer death worldwide. Thus, early diagnosis is of considerable importance. For early screening of lung cancer, computed tomography (CT) has been used as the gold standard. Chest digital tomosynthesis (CDT) is a recently introduced modality for lung cancer screening with a relatively low radiation dose compared to CT. The dual energy material decomposition method has been proposed for better detection of pulmonary nodules by means of reducing anatomical noise. In this study, the possibility of material decomposition in CDT was tested by both a simulation study and an experimental study using a CDT prototype. The Geant4 application for tomographic emission (GATE) v6 and tungsten anode spectral model using interpolating polynomials (TASMIP) codes were used for the simulation study to create simulated phantom shapes consisting of five inner cylinders filled with different densities of bone and airequivalent materials. Furthermore, the CDT prototype system and human phantom chest were used for the experimental study. CDT scan in both the simulation and experimental studies was performed with linear movement and 21 projection images were obtained over a 30 degree angular range with a 1.5 degree angular interval. To obtain materialselective images, a projectionbased energy subtraction technique was applied to high and low energy images. The resultant simulation images showed that dual-energy reconstruction could achieve an approximately 32% higher contrast to noise ratio (CNR) in images and the difference in CNR value according to bone density was significant compared to single energy CDT. Additionally, image artifacts were effectively corrected in dual energy CDT simulation studies. Likewise the experimental study with dual energy produced clear images of lung fields and bone structure by removing unnecessary anatomical structures. Dual energy tomosynthesis is a new technique;therefore, there is little guidance regarding its integrati

关键词： X-ray radiography and digital radiography (DR) computerized Tomography (CT) and Computed Radiography (CR) medical-image reconstruction methods and algorithms, computer-aided diagnosis medical-image reconstruction methods and algorithms, computer-aided software

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Microtomography with sandwich detectors for small-animal bone imaging

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JOURNAL OF INSTRUMENTATION 2016年第10期11卷 10011-10011页

作者： Kim, S. H. Kim, D. W. Kim, D. Youn, H. Cho, S. Kim, H. K. Pusan Natl Univ Sch Mech Engn Busan 46241 South Korea Pusan Natl Univ Yangsan Hosp Dept Radiat Oncol Gyeongsangnam Do 50612 South Korea Korea Adv Inst Sci & Technol Dept Nucl & Quantum Engn Daejeon 34141 South Korea Pusan Natl Univ Ctr Adv Med Engn Res Busan 46241 South Korea

An x-ray radiographic system consisting of two detectors in tandem, or a sandwich detector, can produce dual-energy image from a single-shot exposure. Subtraction of two images obtained from the two detectors can produce a sharper image through an unsharp masking effect if the two images are formed at different spatial resolutions. This is indeed possible by incorporating different thicknesses of x-ray conversion layers in the detectors. In this study, we have developed a microtomography system with a sandwich detector in pursuit of high-resolution bone-enhanced small-animal imaging. The results show that the bone-enhanced images reconstructed from the dual-energy projection data provide higher visibility of bone details than the conventionally reconstructed images. The microtomography with the single-shot dual-energy sandwich detector will be useful for the high-resolution bone-enhanced small-animal imaging.

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

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Preliminary study on a chest digital tomosynthesis: development and evaluation

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JOURNAL OF INSTRUMENTATION 2015年第10期10卷 P10035-P10035页

作者： Lee, Y. Lee, S. Eulji Univ Dept Radiol Sci Songnam Gyeonggi Do South Korea Konyang Univ Dept Radiol Sci Daejeon South Korea

Chest digital tomosynthesis (chest DTS) has been recently introduced to overcome the limitations for high patient dose of conventional X-ray radiography and of a cone-beam computed tomography (CBCT) in studies of overlap of anatomical structures. In the present study, we constructed chest DTS system with amorphous-silicon (a-Si) digital flat-panel detector with pixel pitch of 143 x 143 mu m(2) based upon filtered backprojection (FBP) reconstruction methods We performed both experiments and systematic simulations using our chest DTS system. The image performances were evaluated by means of root-mean-square error (RMSE) and signal difference-to-noise ratio (SDNR) with respect to scan angles such as +/- 5 degrees, +/- 10 degrees, +/- 15 degrees, and +/- 20 degrees. We also performed experiments using our chest DTS system. According to the results, the image performances obtained from chest DTS are improved by using our wide scan angle approach The chest DTS slices showed an improvement in the depth resolution with increasing scan angle. It was found that the optimized filter with a Hanning window to limit the high-frequency components improves image performance because of noise reduction. The chest DTS slices showed an improvement in the depth resolution with increasing scan angle. Both simulation and experimental results showed the same tendency when image performances quantitatively compared. Based on our results, we successfully obtained chest DTS reconstruction images by using a FBP method and promising to application to field of medical imaging.

关键词： Detector design and construction technologies and materials medical-image reconstruction methods and algorithms, computer-aided diagnosis X-ray radiography and digital radiography (DR)

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Automatic breast density classification using neural network

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JOURNAL OF INSTRUMENTATION 2015年第12期10卷 T12002-T12002页

作者： Arefan, D. Talebpour, A. Ahmadinejhad, N. Asl, Kamali Shahid Beheshti Univ Dept Radiat Med Engn Tehran Iran Shahid Beheshti Univ Dept Comp Engn & Sci Tehran Iran Univ Tehran Med Sci Adv Diagnost & Intervent Radiol Res Ctr Imam Khomeini Hosp Tehran Iran

According to studies, the risk of breast cancer directly associated with breast density. Many researches are done on automatic diagnosis of breast density using mammography. In the current study, artifacts of mammograms are removed by using image processing techniques and by using the method presented in this study, including the diagnosis of points of the pectoral muscle edges and estimating them using regression techniques, pectoral muscle is detected with high accuracy in mammography and breast tissue is fully automatically extracted. In order to classify mammography images into three categories: Fatty, Glandular, Dense, a feature based on difference of gray-levels of hard tissue and soft tissue in mammograms has been used addition to the statistical features and a neural network classifier with a hidden layer. image database used in this research is the mini-MIAS database and the maximum accuracy of system in classifying images has been reported 97.66% with 8 hidden layers in neural network.

关键词： medical-image reconstruction methods and algorithms, computer-aided diagnosis Pattern recognition, cluster finding, calibration and fitting methods image processing, X-ray mammography and scinto- and MRI-mammography

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A 3D reconstruction solution to ultrasound Joule heat density tomography based on acousto-electric effect: a simulation study

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JOURNAL OF INSTRUMENTATION 2014年第10期9卷 P10004-P10004页

作者： Yang, Renhuan Song, Aiguo Li, Xiao Dong Lu, Yang Yan, Ruqiang Xu, Baoguo Li, Xu Jinan Univ Coll Informat & Technol Guangzhou 510632 Guangdong Peoples R China Southeast Univ Sch Instrument Sci & Engn Nanjing 210096 Jiangsu Peoples R China Johns Hopkins Univ Dept Radiol & Radiol Sci Baltimore MD 21205 USA

A 3D reconstruction solution to ultrasound Joule heat density tomography based on acousto-electric effect by deconvolution is proposed for noninvasive imaging of biological tissue. Compared with ultrasound current source density imaging, ultrasound Joule heat density tomography doesn't require any priori knowledge of conductivity distribution and lead fields, so it can gain better imaging result, more adaptive to environment and with wider application scope. For a general 3D volume conductor with broadly distributed current density field, in the AE equation the ultrasound pressure can't simply be separated from the 3D integration, so it is not a common modulation and basebanding (heterodyning) method is no longer suitable to separate Joule heat density from the AE signals. In the proposed method the measurement signal is viewed as the output of Joule heat density convolving with ultrasound wave. As a result, the internal 3D Joule heat density can be reconstructed by means of Wiener deconvolution. A series of computer simulations set for breast cancer imaging applications, with consideration of ultrasound beam diameter, noise level, conductivity contrast, position dependency and size of simulated tumors, have been conducted to evaluate the feasibility and performance of the proposed reconstruction method. The computer simulation results demonstrate that high spatial resolution 3D ultrasound Joule heat density imaging is feasible using the proposed method, and it has potential applications to breast cancer detection and imaging of other organs.

关键词： image reconstruction in medical imaging medical-image reconstruction methods and algorithms, computer-aided diagnosis Multi-modality systems medical-image reconstruction methods and algorithms, computer-aided software

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An in-beam PET system for monitoring ion-beam therapy: test on phantoms using clinical 62 MeV protons

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JOURNAL OF INSTRUMENTATION 2014年第4期9卷 C04005-C04005页

作者： Camarlinghi, N. Sportelli, G. Battistoni, G. Belcari, N. Cecchetti, M. Cirrone, G. A. P. Cuttone, G. Ferretti, S. Kraan, A. Retico, A. Romano, F. Sala, P. Straub, K. Tramontana, A. Del Guerra, A. Rosso, V. Univ Pisa Dept Phys I-56127 Pisa Italy Ist Nazl Fis Nucl Sez Pisa I-56127 Pisa Italy Ist Nazl Fis Nucl Sez Milano I-20133 Milan Italy Ist Nazl Fis Nucl Lab Nazl Sud I-95125 Catania Italy

Ion therapy allows the delivery of highly conformal dose taking advantage of the sharp depth-dose distribution at the Bragg-peak. However, patient positioning errors and anatomical uncertainties can cause dose distortions. To exploit the full potential of ion therapy, an accurate monitoring system of the ion range is needed. Among the proposed methods to monitor the ion range, Positron Emission Tomography (PET) has proven to be the most mature technique, allowing to reconstruct the beta(+) activity generated in the patient by the nuclear interaction of the ions, that can be acquired during or after the treatment. Taking advantages of the spatial correlation between positron emitters created along the ions path and the dose distribution, it is possible to reconstruct the ion range. Due to the high single rates generated during the beam extraction, the acquisition of the beta(+) activity is typically performed after the irradiation (cyclotron) or in between the synchrotron spills. Indeed the single photon rate can be one or more orders of magnitude higher than normal for cyclotron. Therefore, acquiring the activity during the beam irradiation requires a detector with a very short dead time. In this work, the DoPET detector, capable of sustaining the high event rate generated during the cyclotron irradiation, is presented. The capability of the system to acquire data during and after the irradiation will be demonstrated by showing the reconstructed activity for different PMMA irradiations performed using clinical dose rates and the 62 MeV proton beam at the CATANA-LNS-INFN. The reconstructed activity widths will be compared with the results obtained by simulating the proton beam interaction with the FLUKA Monte Carlo. The presented data are in good agreement with the FLUKA Monte Carlo.

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

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MARS spectral molecular imaging of lamb tissue: data collection and image analysis

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JOURNAL OF INSTRUMENTATION 2014年第2期9卷 P02005-P02005页

作者： Aamir, R. Chernoglazov, A. Bateman, C. J. Butler, A. P. H. Butler, P. H. Anderson, N. G. Bell, S. T. Panta, R. K. Healy, J. L. Mohr, J. L. Rajendran, K. Walsh, M. F. de Ruiter, N. Gieseg, S. P. Woodfield, T. Renaud, P. F. Brooke, L. Abdul-Majid, S. Clyne, M. Glendenning, R. Bones, P. J. Billinghurst, M. Bartneck, C. Mandalika, H. Grasset, R. Schleich, N. Scott, N. Nik, S. J. Opie, A. Janmale, T. Tang, D. N. Kim, D. Doesburg, R. M. Zainon, R. Ronaldson, J. P. Cook, N. J. Smithies, D. J. Hodge, K. Univ Otago Dept Radiol Ctr Bioengn Christchurch New Zealand Univ Canterbury HIT Lab NZ Christchurch 1 New Zealand CERN Geneva Switzerland Univ Canterbury Dept Elect & Comp Engn Christchurch 1 New Zealand MARS Bioimaging Ltd Christchurch New Zealand Univ Canterbury Dept Phys & Astron Christchurch 1 New Zealand Univ Canterbury Dept Biochem Christchurch 1 New Zealand Univ Otago Dept Orthopaed Surg & MSM Christchurch New Zealand Univ Canterbury Dept Math & Stat Christchurch 1 New Zealand King Abdulaziz Univ Dept Nucl Engn Jeddah 21413 Saudi Arabia ILR Christchurch New Zealand Scott Technol Ltd Christchurch New Zealand Univ Otago Dept Radiat Therapy Wellington New Zealand Univ Otago Dept Med Christchurch New Zealand CDHB Dept Med Phys & Bioengn Christchurch New Zealand

Spectral molecular imaging is a new imaging technique able to discriminate and quantify different components of tissue simultaneously at high spatial and high energy resolution. Our MARS scanner is an x-ray based small animal CT system designed to be used in the diagnostic energy range (20-140 keV). In this paper, we demonstrate the use of the MARS scanner, equipped with the Medipix3RX spectroscopic photon-processing detector, to discriminate fat, calcium, and water in tissue. We present data collected from a sample of lamb meat including bone as an illustrative example of human tissue imaging. The data is analyzed using our 3D Algebraic reconstruction Algorithm (MARS-ART) and by material decomposition based on a constrained linear least squares algorithm. The results presented here clearly show the quantification of lipid-like, water-like and bone-like components of tissue. However, it is also clear to us that better algorithms could extract more information of clinical interest from our data. Because we are one of the first to present data from multi-energy photon-processing small animal CT systems, we make the raw, partial and fully processed data available with the intention that others can analyze it using their familiar routines. The raw, partially processed and fully processed data of lamb tissue along with the phantom calibration data can be found at http://***/10092/8531.

关键词： X-ray detectors computerized Tomography (CT) and Computed Radiography (CR) medical-image reconstruction methods and algorithms, computer-aided diagnosis Data acquisition concepts

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Reducing beam hardening effects and metal artefacts in spectral CT using Medipix3RX

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JOURNAL OF INSTRUMENTATION 2014年第3期9卷 P03015-P03015页

作者： Rajendran, K. Walsh, M. F. de Ruiter, N. J. A. Chernoglazov, A. I. Panta, R. K. Butler, A. P. H. Butler, P. H. Bell, S. T. Anderson, N. G. Woodfield, T. B. F. Tredinnick, S. J. Healy, J. L. Bateman, C. J. Aamir, R. Doesburg, R. M. N. Renaud, P. F. Gieseg, S. P. Smithies, D. J. Mohr, J. L. Mandalika, V. B. H. Opie, A. M. T. Cook, N. J. Ronaldson, J. P. Nik, S. J. Atharifard, A. Clyne, M. Bones, P. J. Bartneck, C. Grasset, R. Schleich, N. Billinghurst, M. Univ Otago Christchurch 8140 New Zealand Univ Canterbury Christchurch 8140 New Zealand CERN European Org Nucl Res CH-1211 Geneva Switzerland MARS Bioimaging Ltd Christchurch New Zealand Canterbury Dist Hlth Board Christchurch 8140 New Zealand ILR Christchurch New Zealand Univ Otago Wellington 6021 New Zealand

This paper discusses methods for reducing beam hardening effects and metal artefacts using spectral x-ray information in biomaterial samples. A small-animal spectral scanner was operated in the 15 to 80 keV x-ray energy range for this study. We use the photon-processing features of a CdTe-Medipix3RX ASIC in charge summing mode to reduce beam hardening and associated artefacts. We present spectral data collected for metal alloy samples, its analysis using algebraic 3D reconstruction software and volume visualisation using a custom volume rendering software. The cupping effect and streak artefacts are quantified in the spectral datasets. The results show reduction in beam hardening effects and metal artefacts in the narrow high energy range acquired using the spectroscopic detector. A post-reconstruction comparison between CdTe-Medipix3RX and Si-Medipix3.1 is discussed. The raw data and processed data are made available (http://***/10092/8851) for testing with other software routines.

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

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Simulation of dark-field imaging of micro-calcifications in human breast tissue with X-ray Talbot-Lau interferometry

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JOURNAL OF INSTRUMENTATION 2014年第5期9卷 C05028-C05028页

作者： Ritter, A. Anton, G. Bayer, F. Goedel, K. Pelzer, G. Rieger, J. Weber, T. Zang, A. Michel, T. Univ Erlangen Nurnberg ECAP D-91058 Erlangen Germany

A simulation of dark-field imaging of sub-resolution structures with X-ray Talbot-Lau interferometry is presented. Data obtained from the simulation shows good agreement to a signal found in the dark-field image of a surgically removed sample of human breast tissue containing micro calcifications. A measure for the type of micro calcifications is introduced which can be calculated from dark-field signals. In a further analysis of the simulated data, it can be shown that the measure can be used to discriminate between different calcifications types.

关键词： Simulation methods and programs medical-image reconstruction methods and algorithms, computer-aided diagnosis Analysis and statistical methods X-ray mammography and scinto- and MRI-mammography

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